Final Report Summary - INCAS (Integration of Nanoreactor and multisite CAtalysis for a Sustainable chemical production)
Executive Summary:
INCAS general objective is to provide new tools for process intensification and enhanced selectivity by catalysis. In addition, the methodologies facilitate safer and more energy-efficient production routes. Higher-yield, cleaner and more resource-efficient synthesis of large volumes of chemicals will be a benefit not only to the process routes highlighted but also to applications including fine chemical production and environmental clean-up or remediation. Finally, the project will provide a much-needed framework to analyze the sustainability of various manufacturing processes.
INCAS project concept to promote a sustainable chemistry and more eco-efficient chemical syntheses is to integrate nanoreactor, membrane and advanced catalytic concepts for two types of industrially relevant processes:
• line 1: the direct synthesis of H2O2 and its in-situ use in propene oxide synthesis;
• line 2: the safer synthesis of diphenylcarbonate (DPC).
The aim is to increase efficiency with a reduced number of unit operations via process integration. The concept goes beyond state-of-the-art microreactors that employ microchannels to confine chemical reactions and enhance speed, yield and safety. It exploits nano-size channels and an ordered sequence of catalytic sites along the axial direction of those channels in a membrane providing a vectorial pathway for multi-site catalytic reactions. The concept applies to reactions (as those indicated above), where cascade processes are not possible or not effective.
The use of nano-designed catalytic membrane for transient generation of risky intermediates will go beyond the on-site/on-demand production concept for safer operations. Toxic reactants produced as a result of transformations are immediately converted into harmless entities to completely eliminate storage, which is minimized but not eliminated in on-site/on-demand microreactor production concepts.
The project Consortium to achieve these challenging objectives is formed from 11 beneficiaries, 6 of which are companies, 4 research & education Institutions and one a non-profit research association.
The project final expected impacts are to develop:
i. new approaches in process intensification through a novel concept of multiphase nanoreactor design,
ii. new approaches in multifunctional catalyst design by integrating catalyst and membrane functionalities in an approach aimed at process intensification,
iii. new approaches for intrinsically safer design for reactions involving risky reagents.
The final result of the project was to verify the applicability and scalability of new concepts in catalysis related to the development of novel nanoreactors and related catalysts for the two listed target reactions and how they can improve (in these industrially-relevant multistage reactions) process intensification, sustainability (in terms of resource and energy efficiency) and safety of operations. Functional to this general objective was the development of catalytic nanomembranes, and of the associated novel reactor concepts and engineering. Due to challenging objective of developing novel nanoreactor concepts, the demonstration activities in the project were limited to the proof-of-the-concepts.
In the first two years the focus was on the lab-scale experimentation to develop and tests the reactor concepts, while in the 2nd part of the project the activities were centered on one side on the specific investigation of the performances of the nanoreactors in the two lines of activity and from the other side on the investigation of the issue of scaling the catalyst/membrane and nanoreactors.
Project Context and Objectives:
Promoting a sustainable chemistry and more eco-efficient chemical syntheses requires new efficient tools and working examples, which catalyze the transformation of the energy- and capital-intensive industrial chemical production. A key factor to foster this change is to develop integrated eco- and energy-efficient syntheses, which imply the capacity to innovate in the field of process intensification, a key for industrial competitiveness, improved use of resources, reduction of the amount of waste and emissions, as well as better safety.
The project context is to address these challenging objectives by integrating nanoreactor, membrane and advanced catalytic concepts. The key concept is the use of nano-designed catalytic membrane for transient generation of risky intermediates, going beyond the on-site/on-demand production concept for safer operations.
The other key concept is to have a step-forward in the integration of microreactor technology with catalysis, two of the crucial pillars to foster a sustainable industrial chemistry. They are key components of process intensification to transform from energy- and capital-intensives to safer and eco-friendly processes, with positive impact also on the competitiveness of chemical industry.
A solution is a modular process design, based on the concept of parallel reaction units, as opposite to scale-economy approach used currently in the chemical industry. Between the advantages:
(i) Safety: less storage and/or transportation of hazardous materials, reducing the likelihood of accidents, and any accidents that do occur will be smaller and less catastrophic. Possibility of realize a delocalized and on-time production.
(ii) Cost and time in introducing new processes: capital costs, transportation costs, and inventory costs are all lower. Easier introduction of new processes on smaller scale; productivity can be increased later by adding new units. Faster time from discovery to industrial production. Easier customization.
(iii) Cycle avoidance: existing large plants consistently suffer from over- and under-capacity scenarios, leading to typical boom-bust cycles.
This new approach requires a next step in an integrated microreactor and catalyst design. In fact, a key aspect for success, and a reduction in energy and capital intensity, is to realize in a single unit complex multistage processes. This is a key for safer and environmental-friendly operations, because there is a reduction of the stages with consequent decrease in energy consumption and waste generation, and the elimination of the storage of possible dangerous intermediates. The approach typically used in microreactor technology is the miniaturization of the reactor and other unit operations, to make compact devices where the reduction of mass and heat transfer leads to process intensification. However, the real potential of using this technology to realize in a single unit complex multistage reactions has been scarcely investigated, because requires a further step in an integrated microreactor and catalyst design, the core aspect of this proposal.
Usually, microreactors have channels in the micrometer diameter range (around 100-150 micron), while the more effective integration between microreactor and catalysis require developing reactors with channels of nanometric size. They are interesting also in general terms, because would further increase of one-two order of magnitude the possible process intensification. In terms of safety, the passage from micro- to nano-reactor would bring several benefits. It is known that the higher wall-to-volume ratio in microreactors with respect to conventional reactors, allows to effectively quenching radical-type reactions and runaway effects. In nanoreactors, the further increase of one-two order of magnitude in the wall-to-volume ratio will further increase safety of operations, allowing, for example, operating without risks inside the explosion region, or with highly exothermic reactions. The integration between nanoreactor and catalysis is thus a key factor towards scientific and technological breakthrough in synthesis for a sustainable chemical production.
The use of catalytic membrane as nano-reactor offers a further possibility to implement novel concepts for safer industrial syntheses. Phosgene is central to the chemistry of pharmaceuticals, polyurethanes, and polycarbonates; a huge market sector generating 8 million tons of products. Phosgene, however, is a highly reactive chemical, and very toxic (TLV = 0.1 ppm), and its manufacture poses serious problems. For this reason, from about two decade there is a large effort in finding safer substitutes such as DMC. Despite these concerns, 5–6 million tons y-1 of phosgene are still produced and used worldwide, while a greener substitute such as DMC has a market about 20-25 times lower, due to techno-economic reasons. From the industrial perspective, the effort has been thus mainly directed towards a safer use of phosgene (on-site or on-demand production) more than to its substitution. The use of catalytic membrane allows to further progress in this direction, implementing the concept of ‘‘dynamic nanoreactors’’ where phosgene is produced and immediately converted in the phosgenation reaction. We indicate this concept as transient phosgene generation. The storage of phosgene is eliminated, and the amount of toxic chemicals becomes negligible. Reduced dimensions allow also confinement of the reactor and supply system, further minimizing the risks and possible leakages.
The project vision for safer and sustainable industrial chemistry is thus centered on these aspects:
(i) to realize efficient modular-design of industrial chemical synthesis, also for large-scale processes, as a decisive factor to accelerate the introduction of novel processes, and enhance competiveness;
(ii) to progress with respect to actual microreactors as necessary step to move in this direction and realized by integrating nanoreactor, membrane and advanced catalytic concepts;
iii) to utilize this novel design as a key element to improve safety, as more effective (time, cost) to accelerate the transition to a safer and sustainable industrial chemistry with respect to redesign the process using alternative reactants requiring large investments costs.
Project main objectives
The project aims is to explore, with reference to the two keys industrial processes listed below
• line 1: the direct synthesis of H2O2 and its in-situ use in propene oxide synthesis;
• line 2: the safer synthesis of dyphenilcarbonate DPC via in situ synthesis of COCl2
the possibility to achieve more efficient processes with a reduced number of unit operations by realizing process integration through the use of novel nanoreactors concepts. The aim is to increase efficiency with a reduced number of unit operations via process integration. The concept goes beyond state-of-the-art microreactors that employ microchannels to confine chemical reactions and enhance speed, yield and safety. It exploits nano-size channels and an ordered sequence of catalytic sites along the axial direction of those channels in a membrane providing a vectorial pathway for multi-site catalytic reactions. The concept applies to reactions (as those indicated above), where cascade processes are not possible or not effective.
The general objective of INCAS project is to provide new tools for process intensification and enhanced selectivity by catalysis. In addition, the methodologies facilitate safer and more energy-efficient production routes. Higher-yield, cleaner and more resource-efficient synthesis of large volumes of chemicals will be a benefit not only to the process routes highlighted but also to applications including fine chemical production and environmental clean-up or remediation. Finally, the project will provide a much-needed framework to analyze the sustainability of various manufacturing processes.
The use of nano-designed catalytic membrane for transient generation of risky intermediates will go beyond the on-site/on-demand production concept for safer operations. Toxic reactants produced as a result of transformations are immediately converted into harmless entities to completely eliminate storage, which is minimized but not eliminated in on-site/on-demand microreactor production concepts.
The project has highly challenging objectives, because no proof of the concept of the possibility to implement these concepts was available at project start. It also has many materials challenges, for example in realizing (nano)membranes, their scale-up, in development (nano)carbon materials for phosgene synthesis, etc. Finally, many technical challenges were also present: how scale-up reactors, design of (nano)-reactors, catalysis in membrane interface. As a consequence of this high risk/high gain project, the project objectives evolved during the project, although maintaining the focus on the general project aim.
Project Results:
The project structure is organized in four main scientific WPs, plus one WP dedicated to dissemination and exploitation of the results and one WP project management and coordination. The main objectives for the core scientific WPs were the following:
WP1: prepare reliable catalytic nanomembranes to be used in the nanoreactors for the H2O2 direct synthesis, PO synthesis with integrated H2O2 generation and DPC synthesis via in situ synthesis of COCl2.
WP2: assemble, test and optimize the nanoreactors for the H2O2 direct synthesis, PO synthesis with integrated H2O2 generation and DPC synthesis with integrated COCl2 generation.
WP3: use the catalyst/membrane and nanoreactors developed in WP1 and WP2, and tests in the reactions of H2O2 direct synthesis, and PO synthesis with integrated H2O2 generation.
WP4: use the catalyst/membrane and nanoreactors developed in WP1 and WP2, and tests in the DPC synthesis with in-situ transient generation of phosgene.
Some of the key results obtained in these WPs are the following:
In WP1: i) produced, characterised, modified and assessed AAO (anodic alumina oxide) membranes, ii) synthesised and deposited Pd nanoparticles for catalyst substrates, iii) synthesised carbon-based membranes and zeolite coated systems, iv) engineered testing equipment facilities, v) modelled substrate and catalyst system configurations, vi) reviewed, identified and progressed alternatives e.g. tubular ceramic
In WP2: i) developed flat-type nanoreactor for line 1 as well as tubular-type membrane (nano)reactor, ii) fabricated mock-up prototype, iii) developed hollow-fiber modules for scaling-up reactor in line 1, iv) developed membrane reactors to work in gas-liquid and gas-gas phases, v) simulations of the membrane model for the phosgene synthesis + phosgenation of phenol to diphenyl carbonate (DPC) , vi) design of the prototype reactor for line 2 vii) fabrication of the reactor-prototype for line 2
In WP3: i) tested different reactor configurations and combinations of multilayer membranes, ii) analysis of the different feeding possibilities to operate in safe conditions, iii) scale-up and testing of hollow-fiber configuration, iv) patentability analysis.
In WP4: i) understanding the mechanism of COCl2 formation over carbon catalyst, particularly what are the active sites on the carbon catalyst surface and what is the nature of the transient intermediates, ii) understand the mechanism of deactivation, expecially what triggers deactivation of carbon catalysts and identification of the measures to avoid deactivation / regeneration, iii) identification of stable catalysts and of alternative, non carbon catalysts, iv) design and performing a lab-scale demonstrator, identification of the concept for scaled reactor and application of insight gained for current COCl2 manufacture. In terms of integrated reactor for in situ COCl2 synthesis and immediate conversion (to DPC), different options were analyzed to identify the preferable configuration.Patents for novel recator configuration were filed.
WP5 was related to project dissemination and exploitation. Several publications and presentations at conferences resulted from the project, 3 patents, and a list of exploitable items. Between the activities made: i) maintenance of the website for public and inside consortium activities, ii) presentation of the project’s results and activities during the project’s meetings, iii) drafting and maintaining the dissemination and exploitation plan following the EC’s requirements, iv) establishing the actions for dissemination and exploitation, v) organizing and managing the activities of the Exploitation Committee for protecting the project results, vi) continuous monitoring of the progress of the research within the project to verify which results (a) should be protected by patents and (b) are relevant to exploitation in fields outside the specific scope of the project, take all the actions necessary for successful exploitation of the results of the project.
WP6 was related to project management and coordination. Between the activities made: i) realization and implementation of a coherent and efficient project management and co-ordination of the project in accordance with the budget and the schedule of milestones and deliverables; ii) design and implement the management tools necessary for an efficient and timely project management. In addition to preparing the various contract report and meeting, as well as maintenance of the communication and exchange with the European Commission, it was implemented a continuous monitoring the status of the project’s deliverables and milestones, the handling of legal issues, IPR issues and maintenance of the consortium agreement, the management of knowledge generated by the project and the handling of the project correspondence and the day-to-day requests from partners and external bodies.
Selected main S&T results
Synthesis, characterization, modification and assessment of membranes
The first two years of the project were focused on catalyst/membrane preparation for lab-scale tests while later the effort was directed towards scaling of the catalyst/membrane. Ultimately such membranes were evaluated for their performance as nanoreactors in H2O2 direct synthesis, PO synthesis with integrated H2O2 generation and DPC synthesis with integrated COCl2 generation.
During the first 24 months of the project, more than three basic membrane types have been produced: several with straight-through vertical porous channels and several with mesoporous structures. Two types of membrane with vertically-aligned straight channels have been generated by anodizing either titanium or aluminum: these are generally referred to as anodic titanium oxide (ATO) or anodic aluminum oxide (AAO) membranes. The mesoporous membranes (i.e. no straight-through porous channels) have been prepared by either polymerising siloxanes, TS-1 or with carbon powder.
Initially 60 x 40mm AAO membranes with a capacity to produce 2-4 membranes of this size daily, due largely to the anodizing protocol employed requiring a 2-hour dwell time and constant current and voltage conditions, were prepared. The electrolyte used in the production of AAO membrane types is a mixture of phosphoric and oxalic acids and a carbon counter-electrode. Samples of these types of AAO membranes have been supplied to the relevant partners for their further characterization, modification and assessment.
In parallel, planar ATO membranes (by anodising titanium foil) were also prepared (size about 3 cm diameter). However, this type of membranes lacked a sufficient degree of mechanical or dimensional stability to be employed effectively with the project as a catalyst support material in a reactor assembly. In addition, these ATO membranes adversely affected hydrogen peroxide decomposition.
Novel synthetic routes for both carbon-coating membranes and producing carbon monolithic membranes were also investigated, because the tested commercially available C membrane materials lack of the necessary characteristics. One of the preferred route to prepare these C membranes involves starting from powder type nanocarbons , process in solvents and then cast onto glass plates at room temperature prior to vacuum oven treatment.
POSS (Polyhedral Oligo SilSesquioxane) membrane materials, that are both completely and incompletely condensed variants through different synthesis routes, were also synthetized as well as TS-1 membranes were synthetized and assessed.
Synthesis and deposition Pd nanoparticles for catalyst
Nanoparticle synthesis. In order to identify suitable synthetic methods for the production of palladium nanoparticles started from a review of the open literature. By using H2PdCl4 and PVP, palladium nanoparticles with a narrow particle size distribution and, in the size range desired <5nm diameter, were obtained. A consistent a reproducible synthesis protocol for palladium nanoparticles has been achieved with initial problems identified and resolved. This procedure has been used in all subsequent experiments with palladium nanoparticles
The deposition of palladium nanoparticles on membrane was initially attempted by dropping the palladium nanoparticles solution on the membrane and allowing the solvent to evaporate, but this method proved inconclusive in terms of the deposition of the particles as the amount was too low. After evaluation of different variations on the method, and the investigation of alternative methods such as by homogeneous deposition precipitation (HDP; a solvated metal precursor is deposited on the support surface by the slow and homogeneous introduction of a precipitating agent, generally hydroxyl ions), a method by ligand exchange was adopted. A modification of this method regarded the ligand functionalization of AAO membrane. A specific novel apparatus was introduced to avoid the generation of gradients in nanoparticles. The methodology allowed to produce a consistent and reproducible protocol for palladium nanoparticle deposition on the AAO membranes to prepare samples with uniform and concentrated deposition of the nanoparticles throughout the membrane. The novel catalytic membranes showed good stability.
Synthesis of carbon-based membranes and zeolite coated systems
Carbon coated AAO alumina membranes were investigated. However, a major problem derived from the need to avoid from one side to completely block, or significantly alter the AAO nanomembrane porosity, and from the other side to avoid rupture of the membrane particularly during the annealing procedure. Two types of preparations (differing in the type of carbon-precursor) were selected by using two different precursors for the carbon: glucose and triton X-100. After pyrolysis at 250°C, the best results were obtained with the Triton X-100, where during decomposition the Al2O3 membrane doesn’t stress and the overall appearance was smooth and homogeneous. Permeability tests, as well as characterization of the surface roughness, confirmed that the membranes are suited for testing.
Self-supported carbon membranes were also prepared and evaluated. The method developed consisted in the physical mixture of a carbon powder with an epoxidic resin, co-adding high surface area SiO2 or Al2O3 as “hierarchical agent”. In fact, further dissolution of them by HF, confers the introduction of higher porosity to the composite. This method is particularly advantageous for several reasons:
i) The carbon powder source can be selected: we chose to test a particular carbon onion-like structured, because it seems to be active for the phosgene synthesis. Alternatively, any kind of carbon powder can be added.
ii) The membrane does not need the use of a support: the resin acts as self-structuring agent.
iii) The membrane is mechanically and thermally resistant: the HF attack and the treatment at 220°C generate a stable structure.
iv)The size of the membrane can be easily tuned: since the moisture Carbon/resin/HA is fluid, it can be placed in a specific mold in a way to obtain the desired shape.
The choice of the carbons to incorporate in the membrane was given by the experience of carbon materials used in the COCl2 synthesis. So, as carbon precursor a “onion like” carbon prepared within the project and a carbon supplied from one of the partners were used for membrane preparation.
Characterization techniques and gas permeability tests showed the good accessibility to inner core of membranes. These membranes were utilized in the catalytic tests.
TS-1 membranes. Different deposition procedures to obtain improved alumina membranes supported with thin TS-1 layers were investigated. Thick TS-1 membranes (125μm) through direct in situ synthesis of TS-1 nanocrystals onto AAO membranes were initially prepared. The method was later optimized to produce TS-1 layers with much reduced thickness (35μm). Further studies have carried out high temperature treatments with the TS-1 supported membranes to study their hydrothermal stability and the results showed that no cracks are observed after calcination to 550ºC but the membrane was curved. Following this initial membrane synthesis work, further studies focused on two different approaches: using standard and polymer assisted dip-coating methods. These latter studies have been performed with AAO membranes and the results obtained have shown that the TS-1 seeding was more effective when a polymer electrolyte was employed.
Modelled substrate and catalyst system configurations and engineered testing equipment facilities
For an optimized concept of the membrane nanoreactor, the steps in the reaction need to be de-coupled. In line 1, first H2O2 has to be in situ generated over Pd catalyst and then diffuses over titanium silicalite-1 for the further reaction with propene to produce propylene oxide. The limiting step of the overall reaction (H2O2 production) is taking place in the membrane itself where H2 and O2 are fed over the channels of the membrane. Since hydrogen peroxide is a chemically instable compound due to fast decomposition over different types of materials, this limits the material choice for the membrane. The first requirement has then to ensure that no (or limit) decomposition of H2O2 over the material occurs. A series of initial studies thus focused on this aspect.
An issue in using the flat-type nanomembranes described above is fragility. A possibility investigated regarded the utilization of a non ordered macroporous oxide support on the top of which deposit the ordered membrane layer that will act as a catalytic one. The second suggestion presents the advantage of overcoming the problem of increasing the thickness that can lead to a mass transfer limitation during reaction operation. In fact, by increasing the thickness one of the most important characteristics of the membrane itself is limited and reduced: the gas permeability. In order to understand the performance of the membrane, permeability tests were conducted. Also with suitable modeling it was evaluated the minimum value of the membrane thickness needed for catalytic application. The membrane thickness is an important parameter to be integrated with the catalytic requirements from the reaction. A further modeling was utilized to improve the design of the membrane nanoreactor concept and analyze the characteristics for industrial scaling up.
An important element to optimize and scale-up the integrated reactor in line 1 was to develop a modelling approach to determine the optimal characteristics necessary and the potential results. The reactor model deals with a high pressure gas/liquid system. The purpose of the model is the optimization of the reactor concept by knowing the concentration-diffusion profiles of the different reactants and products along the membrane layers. A working model for the direct synthesis of propylene oxide has been developed. The model shows the dependence of H2O2 conversion and selectivity on the membrane parameters such as the thickness. Also the PO synthesis is strictly connected to the first catalytic layer. In order to reach the scaling up requirements, a Pd/SiO2 membrane thickness between 100-250 µm has to be ensured. The model is also available to understand the influence of other parameters such as the gas partial pressures, liquid and gas flow rates and membrane areas in order to further understand the membrane reactor behavior.
In parallel, density functional theory was used to investigate the direct synthesis of H2O2 over Pd based nanoparticles. The aim of the study was to elucidate the reaction mechanisms for H2O2 obtaining on two representative surfaces of an active Pd nanoparticle in reaction conditions: (i) O/(√5x√5)R27o Pd(100) and (ii) PdO(101).
Development of tubular ceramic nanomembranes
Due to issues presented by flat-type membranes, the focus on the last part of the project was on the development of alternative tubular-type ceramic nanomembranes, to utilize for the scale-up of catalysts/membrane, in relation to reactor design identified in other WPs. In line 1, limited robustness of flat-type membranes caused the need to develop alternative tubular-type membranes, but limited performances of the various configurations tested do not allowed to pass to larger scale prototypes. However, it was explored the use of a reactor based on hollow-fibers as scaled-type prototype. In parallel, investigation was related to deposit the catalyst (Pd and TS-1) on tubular membranes as next step in scaling this type of membranes and to prepare and functionalize with catalysts anodising aluminum foams as scaled flat-type catalyst/membrane systems having higher mechanical robustness. In line 2, the activity was in relation to scaling the catalyst/membrane in relation to prototype and model of reactor defined in simulation studies, and to develop the zeolitic membrane for the two-step phosgene-free DPC synthesis.
Procedures to improve Pd dispersion on alumina tubular membrane were developed and the samples characterized in terms of properties and performance. The procedure developed for Pd incorporation was based on impregnation-decomposition method. The membranes produced gave the best performance in H2O2 direct synthesis, a narrower particle size distribution; and no deactivation as had occurred previously with samples prepared by sol-immobilization procedure. Additionally, the effect of different cycles of thermal treatments on the same membrane was evaluated. A second heat treatment led to a narrower particle size distribution, retained the same degree of metal dispersion on the support and provided an improved product selectivity.
The high selectivity observed on the membrane prepared by impregnation-decomposition (D-I) after heat treatments has been explained on the basis of FTIR characterization where it has been observed that more exposure of homogeneous facets (i.e. less defect sites) is a consequence of preferential exposure of the facets (111). Adsorption of reactants on planar sites (111) seems to be the optimal condition to get direct formation of H2O2. This agrees with theoretical modelling results by DFT method.
Membranes by using two preparation technique (sol immobilization and reduction by hydrazine) were prepared to test alternative configurations for palladium arrangements. The scaling of the deposition of TS-1 on tubular membranes, in order to improve the quality and coverage of TS-1 membranes on alumina tubular supports, was also investigated with the objective being to prepare suitable bi-functional catalytic systems Al2O3@Pd@TS-1 for direct one-step PO production from H2, O2 and C3=. A novel type of composite membranes based on palladium thin layers externally coated with TS-1 nanocrystals, using α-alumina tubes as support substrates was prepared.
Important advances were achieved by identification of the need to seed coated Pd films with TS-1 nanocrystals via a polymer dip-coating process followed by a secondary growth step. In this latter case, micellar gel for secondary growth of the seeded supports was investigated and the resulting membrane consisted of a well-intergrowth layer of TS-1 zeolite with a thickness of 0.7 µm. The TS-1 membrane is strongly attached to the palladium film and no peeling was observed. Electron microscopy characterization confirms the effective presence of outer TS-1 layer onto internal palladium film which is coating the tubular alumina supports.
The possibility to obtain a dense zeolitic membrane on the polymer-coated metallic surface by direct growth of the zeolite crystals and without the previous TS-1 seeding deposited by polymer assisted dip-coating was also analyzed. A densely packed TS-1 membrane was grown on the palladium surface, although visible discontinuities were detected.
Scaling the tubular-membrane approach to develop hollow-fiber reactor
Scaled-up nanoreactor (line 1) was based on the use of hollow-fiber modules. A new reactor prototype for testing them was assembled. A new scenario for the production of PO could be the use of hollow fiber membranes with a lower wall thickness (0.5 mm) then the previous membranes (wall thickness 1.5 mm). Although as known selectivity in H2O2 is limited for operations at low pressure as in the following tests, the results show that hollow-fiber membranes under the same conditions allow about three-four times higher productivity and selectivity with respect to tubular-type membrane R70 benchmark. The approach is thus well suited for scaling-up performances and intensifies the process.
Scaling the preparation to produce anodising aluminum foams.
A thinner, more open-pored structure on aluminum foam using alternative anodizing conditions (with phosphoric electrolytes) was successfully produced for subsequent catalyst deposition and evaluation: initially film thicknesses of <1µm were achieved but it was considered that these also were likely to be too thick and, consequently, oxalic electrolyte options were produced with anodic film thicknesses of 1-2µm but with very fine pore widths of ~30-40nm.
Further studies were then subsequently undertaken on pore widening options with anodized aluminum foam but, despite the “imperfect” anodic film structures initially grown on the anodized aluminum foam, Pd nanoparticles were deposited successfully within the pore structure. Alternative anodising processes were also explored with the aim of identifying open-pored structures of the “required” structure; one of these is hot AC phosphoric acid processing. This procedure provides an anodic film geometry on anodised aluminum which might be considered closer to product application requirements.
In addition, polymer replication from an anodised aluminium substrate – resulting in the creation of a textured polymeric substrate which may have applicability as a catalyst substrate, was developed.
Scaling the preparation of carbon catalytic membranes for line 2
The scaling of the preparation of carbon membrane (line 2), with the aim to improve the synthesis procedures for C-containing membranes was investigated with a focus on:
• thermal stability up to 300°C
• control of membrane thickness in the range 0.3-0.5 mm
• high permeance
• high porosity
• higher carbon loading
Different types of nanocarbons starting materials were utilized. The results demonstrated that a synthesised variant can show comparable and even better properties to commercial systems.
Scaling the preparation of zeolitic membranes for two-step phosgene-free DPC synthesis in line 2
The scaling of the preparation of zeolitic membranes for two-step phosgene-free DPC synthesis (line 2), one of the most promising alternative pathways for DPC synthesis, was also investigated. In the first step the formation of dimethyl carbonate (DMC) from methanol and CO2 takes place, whilst in the second reaction DMC is converted via transesterification with phenol to form DPC as the target molecule. Both of the reaction steps are highly equilibrium constrained. Therefore, besides rational design of efficient catalysts, the selective product separation (i.e. water removal in the 1st step and methanol removal in the 2nd step) is demanded. In a first attempt, LTA zeolitic wafers were synthesised and thoroughly synthesised prior to membrane growth. Similar the case of DMC, in order to enhance the DPC formation, efficient membranes for the methanol removal from phenol abundant solution are required. Therefore, a similar approach as in the case of water/alcohol separation membranes was applied. For a selective MeOH removal for improvement of transesterification yield was achieved by using newly prepared LTA zeolitic membrane. However, the pore-opening ought to be different as in the case of water removal from alcohol. This modification of pore-opening was fulfilled by different cation exchange.
A continuous-flow reactor with on-demanding product separation has been proposed. At the bottom part of the reactor, the reaction would be initialized by DMC formation from methanol and CO2 (catalyzed by ZrO2-based catalyst), co-produced water would be eliminated simultaneously by membrane made by zeolite. Till DMC yield reach certain high level, transesterification of phenol and DMC would started (catalyzed by MoO3- or TiO2-based catalyst), another zeolitic membrane would be applied for methanol removal. At last, DPC would be obtained with high yield..
Development of flat-type nanoreactor for line 1 as well as tubular-type membrane (nano)reactor, fabricated mock-up prototype, developed membrane reactors to work in gas-liquid and gas-gas phases, design of the prototype reactor
The following types of flat-type nanomembranes have been investigated:
- for line 1,
i) alumina (AAO) nanomembranes of about 25 mm in size produced by Innoval and
ii) titania nanomembranes of similar size prepared by INSTM.
Both were produced by anodic oxidation, but the investigation of the titania type membranes was stopped due to both problems of material compatibility and of preparation (severe curling).
- for line 2,
i) carbon-coated nanomembranes (on alumina substrate) and then coated with carbon.
ii) carbon-only membranes prepared using nanocarbon materials and then converted to the flat membranes by casting procedure after addition of suitable additives.
For testing the characteristics of these flat-type nanomembranes (robustness, sealing, permeability), a simplified mock-up reactor was constructed and used.
A new mock-up reactor prototype was also fabricated to investigate the fluid-dynamics of the gas-liquid contact and mixing using the flat alumina AAO membranes. The reactor is designed to carry out reactions in gas/liquid phase: (i) one side is prearranged to feed gas and the other to feed a liquid flux in continuous mode; (ii) the 2 chambers are separated by the membrane. The reactor was designed to have a minimal thickness for the liquid side (about 1 mm), in order to simulate the original design.
Some of the main conclusions from these activities are the following
Line 1:
- a SS prototype was already fabricated, and two reactors were already sent to partners for testing.
- the decision concerning the scaled-up nanoreactor (line 1) was based on the use of hollow-fiber modules. A reactor prototype for this experimentation was designed, assembled and tested.
- the tubular reactor prototype has also been modified to work in gas-liquid phase conditions. This modification was carried out taking account that the formation of H2O2 intermediate is favored in liquid phase at softer reaction conditions. The apparatus were updated for testing membrane in another configuration; feeding a non-explosive mixture 3%H2-97%O2 through the membrane while in the other side the methanolic solution phase is feed as in the previous tests.
In Line 2:
- the design of the prototype reactor was assessed and the reactor-prototype together with o-ring in kalrez, thermocouple and some carbon based membranes send to partners for testing.
- engineering modeling and safety aspects have been considered for the nanoreactor design. They were also used to consider the carbon thickness necessary and to estimate the heat release, also in consideration of the heat control necessary to minimize deactivation.
- based on the elaborative analysis of the integrated system, the final reactor concept of a multi-tubular reactor was put forward and assessed for its ability to reach a realistic commercial capacity of the targeted product DPC.
Development of hollow-fiber modules for scaling-up reactor, fabrication of the reactor-prototype.
A nanoreactor (and related apparatus) for using hollow-fiber modules was designed and assembled as new scale-up reactor prototype.
Increase in PO performances were studied through the use of further membrane catalytic systems studied considering the influence of the following parameters: use Pd films or nanoparticles (seeds), combination of active layers in different order such as Pd@TS-1 or TS-1@Pd membranes, passivation of acidic external groups, increase in the content of active phase and reactions with high oxygen regimes, i.e. using non-explosive H2-O2 mixtures. All these parameters were considered in membrane reactor suitable to work in gas phase. Furthermore, novel tubular reactor prototypes were assembled to better analyze different reaction variables and increase the PO productivity. For this, liquid-gas reactor proto-type was assembled and optimized to compare with the most favorable reaction conditions to generate intermediate in situ H2O2. Moreover, tubular prototype adapted to work with alumina hollow fibers was also designed and optimized trying to increase the productivity and efficiency of the two-step one-pot catalytic process.
Both approaches (i and ii) are complementary, being the advances achieved in batch catalytic studies useful to be applied in the membrane reactor proto-type tasks.
Tested different reactor configurations and combinations of multilayer membranes,
Different configuration/arrangement of Pd/membrane were tested. The best results in the direct synthesis of H2O2 were obtained with the benchmark configuration giving a better productivity, activity (hydrogen conversion) and selectivity respect to arrangements of Pd on the external side. All the membranes tested shown activity toward hydrogen conversion (H2O productivity), which means that the membranes are completely wetted by the methanol solution. The lower selectivities obtained by the catalytic membranes prepared by external Pd deposition are attributed at the higher hydrogen peroxide retention time in the membrane pores (pore length: 1.5 mm, without taking into account the tortuosity factor) in contact with Pd particles. Similar results are obtained with the membranes prepared by N2H4 reduction technique, where we have also a higher H2O production rate in the case of the external palladium arrangement compared with our benchmark.
We might conclude that the higher concentration locally achieved inside the pores of the membranes prepared by external palladium deposition are detrimental in our experimental condition, but might be a key factor for the PO production. A new scenario for the production of PO could be the use of hollow fiber membranes with a lower wall thickness (0.5 mm) than the previous membranes (wall thickness 1.5 mm).
Higher productivity in the PO synthesis were shown by using a specific type of membrane with the reactor configuration as follows: TS-1 layer deposited on the internal side). Based on this result some membranes by using two preparation techniques (sol-immobilization and reduction by Hydrazine) were prepared.
Four different reaction configurations were investigated for tubular membranes:
- Reaction configuration IA: Pd seeds or film are located in the internal side of the alumina supports, and TS-1 membrane is grown over it. Hydrogen is fed from the outer side of the membrane in gaseous phase at constant pressure (2 bar). Propylene and oxygen saturated methanolic solution is continuously circulated on the inner side by means of a peristaltic pump (25 ml/min).
- Reaction configuration IB: Pd seeds or film are located in the external side of the alumina supports, meanwhile TS-1 membrane is in the inner side. Hydrogen is fed from the outer side of the membrane in gaseous phase at constant pressure (2 bar). Propylene and oxygen saturated methanolic solution is continuously circulated on the inner side by means of a peristaltic pump (25 ml/min).
- Reaction configuration IIA: Pd seeds or film are located in the internal side of the alumina supports, and TS-1 membrane is grown over it. Oxygen and hydrogen are fed together in a non-explosive regime by the outer side of the membrane in gaseous phase. Propylene saturated methanolic solution is continuously circulated on the inner side by means of a peristaltic pump (25 ml/min).
- Reaction configuration IIB: Pd seeds or film are located in the external side of the alumina supports, meanwhile TS-1 membrane is in the inner side. Oxygen and hydrogen are fed together in a non-explosive regime by the outer side of the membrane in gaseous phase. Propylene saturated methanolic solution is continuously circulated on the inner side by means of a peristaltic pump (25 ml/min).
Reaction configurations IIA and IIB forced to work with only 3% of H2 in order to be in a non-explosive regime, resulting in lower H2O2 productions, much higher selectivities. This approach could be an interesting alternative, because its use could significantly reduce the amounts of propane formed, being, in any case, necessary to increase the H2O2 productivity to improve the final PO production. On the other hand, reaction conditions IA and IB lead up to now the best H2O2 production results using this kind of tubular membrane reactors. Configurations IIA and IIB, in which H2 and O2 are feed together, did not lead to any production of propylene oxide. These results agree with the results obtained, which showed a low H2O2 production in both configurations when H2-O2 non-explosive mixtures are used.
When the reactions were carried out with the typical configurations, IA and IB, feeding H2 from the outer side and O2 together with C3H6 in the inner side dissolved in methanolic solution, two different results were observed. On the one hand, membranes in which Pd is in seeds form located in the inner side (R73), the PO production does not exist or is too reduced, with propane being the main product. On the other hand, the membrane with Pd film located in the internal side, led to better catalytic results, methoxypropanols were also observed during the reaction. The results indicate that PO production is favured when Pd seeds in the outer side or Pd film in the inner side are coating the alumina support, always feeding separately H2 and O2.
Conclusions of Tubular Membrane Reactor Tests
- TMR prototype in gas reaction conditions is not effective to produce PO in one-pot process (only PO traces are obtained) due to the complete oxidation of Pd species in the catalytic system.
- TMR prototype is effective to produce PO in one-pot process in liquid-gas conditions when H2 and O2 are separately fed in the reaction system. Specifically, in these conditions, the best performances have been obtained when Pd film or Pd nanoparticles are supported into the internal or external side, respectively, of alumina tubular membrane, in presence of internal TS-1 layer. In these conditions, the stabilization of in-situ generated H2O2 is enough to produce PO in the second reaction step.
- Reproducibility test show a strong dependence with the membrane used in all cases. This issue is still a matter of study.
- Feeding together O2 and H2 (using H2-O2 non-explosive mixtures at high O2 regimes) did not led to PO production in any case, due the poor stability and low productivity of in-situ generated H2O2 under these reaction conditions.
- Process optimization is necessary to increase PO yields, analyzing different parameters such as catalyst amount, incorporation of promoters (Au, Pt, Ag), pressure gradients, reduction of propane formation as main reaction product and use of H2O2 stabilizers among the most relevant matters to be considered in the close future.
Tests in batch reactor were also made. Some of the conclusions are the following:
- Bi-functional Pd@TS-1 catalysts are effective to produce directly PO through one-pot two-step process from H2, O2 and C3=, using supercritical CO2 conditions (high pressures ~ 75 bar).
- Best results are obtained using MeOH as co-solvent, ammonium acetate as acidity inhibitor and C3=/H2/O2 molar ratios close to 1/1/1. Higher selectivity to propane was observed when H2/O2 ratio was higher than 1, resulting in a decrease in the PO selectivity.
- In general, H2O as only co-solvent does not favor the PO production, although its negative effect is strongly minimized in the presence of MeOH, overall when Pd@TS-1 catalysts are used.
- The presence of Au/Pd alloy nanoparticles supported onto TS-1 allows the preparation of effective bi-functional catalysts which are more reactive than only Pd counterparts, achieving C3= conversions of ~15%, and PO selectivities and yields close to 82% and 11% respectively, reducing significantly the propane formation (SC3~10%).
As general conclusions from these tests it may be indicated
- Bi-functional catalytic systems (powder or membrane system), based on Pd species (nanoparticles or films) and TS-1 zeolite (powder or dense layer) are effective for direct PO production from H2, O2 and C3= through in-situ generated H2O2.
- High PO performances are obtained in batch catalytic processes with supercritical CO2 conditions at high pressures and with the additional presence of metallic promoters (Au, Pt).
- Tubular membrane reactor (TMR) prototype is valid to carry out the one-pot two-step process in liquid-gas conditions, using bi-functional Al2O3/Pd/TS-1 membranes, feeding separately H2 and O2 into the reaction system. The stabilization of in-situ generated H2O2 in methanolic solutions, containing saturated O2 and C3=, is necessary.
Engineering of the scaled-up nanoreactor and assessment of the nanoreactor prototypes
Aspects analyzed regarded:
1. The detailed design of the reactor (dimension, shape, manner of heat transfer etc.).
2. The total mass balance of the reactor.
3. The process scheme including operating conditions.
These specifications were derived from and based on the earlier work of the other partners. However, the results of the process in line 1 are highly depending on some assumption made, which the engineering modelling developed later showed the necessity to be modified. In particular: i) the use of very diluted conditions, about 1:500 mainly to remove the heat of reaction with the flow of methanol itself; by using a different approach for heat removal and working under more optimized conditions the ratio can be decreased to a value estimated around 1:20, determining a complete change in costs; ii) the possible significant larger optimization in performances, by using a hollow-fiber type of reaction and optimized membrane configuration, as well as operative conditions, leading to an improvement by a factor about 20 in the productivities. Therefore, present assessment cannot be considered definitive, but as a case limit. It is possible a significant decrease in the costs and reactor sizes, but further experimentation is necessary.
Understanding the mechanism, particularly what are the active sites on the carbon catalyst surface and what is the nature of the transient intermediates
The activities are to: (i) Develop concepts for the mechanism of COCl2 formation over the carbon catalyst surface; (ii) verify the proposed mechanistic concepts by molecular modeling applying DFT analysis, (iii) study experimentally the carbon-chlorine interaction; (iv) study CO interaction with the active sites and activated carbon – chlorine complex; (v) study experimentally COCl2 synthesis in small scale batch reactors. The scope of these activities was to elucidate the mechanism of phosgene formation over carbon catalyst, which goes along with the identification of the catalytically active sites. This knowledge will support other tasks dealing with catalyst deactivation, the development of stable catalysts and the identification of process conditions inhibiting deactivation. A concept for Cl2 activation over carbon surfaces was developed and supported with corresponding DFT calculations. Experimental evidence for the postulated mechanism and catalytically active sites were also provided. Between the aspects investigated:
i) *C…Cl2 interactions was investigated experimentally, using various advanced spectroscopic techniques and a pulse setup, to gain experimental evidence for the proposed mechanism / active sites and to get insight into elementary processes occurring during interaction of Cl2 with C.
ii) In situ temperature-dependent ESR measurements of Cl2…C interaction using model carbon materials were performed, to evidence the nature of transiently formed chlorine intermediates.
iii) The interaction of CO with Cl2…C complexes was investigated, to understand the reactivity of various activated chlorine molecules towards CO.
iv) Synthesis and thorough characterization of new model carbon materials for phosgene synthesis was made to identify potential active sites on carbon material surface to enable a better understanding on the contribution of various sites on the Cl2 activation and COCl2 synthesis.
v) The influence of various process parameters and material pre-treatments on the formation of chlorinated side products during phosgene synthesis was analyzed.
v) Synthesis and mechanistic investigations on N-doped carbon materials were performed.
Understand the mechanism of deactivation, especially what triggers deactivation of carbon catalysts and identification of the measures to avoid deactivation / regeneration, identification of stable catalysts and of alternative, non carbon catalysts
Thorough characterize state of the art carbon catalysts (unused / fresh) for phosgene synthesis; (ii) derive structure-activity relationships by comparison of analytical data obtained from unused and used carbon catalysts; (iii) synthesize model carbon materials with an emphasis on given structural / chemical features to prove mechanistic assumptions, (iv) experimentally investigate factors influencing carbon catalyst deactivation. The scope is to investigate and understand the deactivation of carbon catalyst during phosgene synthesis.
Between some of the activities for this scope:
i) DFT analysis on the thermodynamics of Cl2 interaction with highly pre-chlorinated fullerene model carbon surfaces, to investigate if energetics of chlorination depend on degree of pre-chlorination of the model
ii) Investigations on catalyst regeneration. Carbon catalyst regeneration by treatment with CO, N2 and H2 was investigated at different temperatures
iii) Testing of further carbon materials in phosgene synthesis. Relevant carbon materials were investigated for their stability during COCl2 synthesis at different temperatures
iv) Comparison of catalytic properties of powder-type carbon materials and carbon extrudates, to get closer to the real catalyst material in phosgene plants
v) Testing of Al2O3 as a potential non-carbon catalyst for phosgene synthesis, to identify a non carbon catalyst with potentially higher stability regarding deactivation
As result of these activities, Stable catalysts for COCl2 synthesis were identified, based on the following studies: (i) process conditions for reduced / inhibited deactivation of carbon catalysts; (ii) properties of tailored carbon materials that are active and stable catalysts for COCl2 synthesis; iii) alternative non-carbon catalysts that can be used within membrane concept for DPC synthesis.
The results suggested that N-doping of the carbon structure increases the stability of the catalysts during COCl2 synthesis. However, at the same time catalyst activity is significantly reduced. A different mechanism for Cl2 activation observed for pure and N-doped carbon materials may serve as an explanation for their different deactivation properties.
Activated carbon materials with strongly improved stability when compared with state of the art activated carbon catalysts were identified in the course of catalyst screening experiments at lab-scale. The identification of carbon catalysts within improved stability is a major advance not only in terms of a better understanding of the factors responsible for carbon catalyst deactivation in the future but also regarding possible implementation of the identified materials in current COCl2 generators.
Alternative to carbon based catalysts, various metal based catalysts were selected and tested for catalytic Cl2 activation for phosgene productions. In-situ MS measurements conducted during chlorine adsorption in the presence of 5 wt. % CO containing He atmosphere at 150 °C have shown that among others, some type of alternative materials are a potential non-carbon catalyst for the COCl2 synthesis.
Design and performing a lab-scale demonstrator, identification of the concept for scaled reactor and application of insight gained for current COCl2 manufacture.
The activities are to (i) study the performances of lab-scale catalyst/membrane and nanoreactor developed in other WPs, (ii) analyze the effect of the reaction conditions and operative parameters (flux through the membrane, liquid flow, design of nanoreactor, etc.), (iii) compare the behavior (kinetics, stability) with that using conventional reactor/catalysts, and (iv) optimize the performances. The scope is to test lab-scale nanoreactor prototypes both in phosgene synthesis and coupled phosgene and DPC synthesis.
Between the activities for this objective:
i) membrane tester, with safety check and heater
ii) integrated fixed bed reactor, with design and assembly, cold commissioning
iii) integrated membrane tester, with tubular carbon membranes, membrane holder for integrated reactor, permeability tests and catalytic activity.
Various approaches for lab scale testing and demonstration were followed. Goal was to realize and test an integrated reactor combining in situ COCl2 synthesis and phosgenation of phenol to DPC. Regarding COCl2 synthesis two approaches were followed: COCl2 generation in a membrane or in a fixed bed reactor. A membrane tester was designed to test carbon membrane stemming from partners, a separate inlet is intended to provide the possibility to feed phenol into the reactor.
An integrated reactor for DPC synthesis at elevated temperatures and pressures via in situ generated COCl2 was designed and assembled. Both, the utilization of carbon membranes and a fix bed for COCl2 generation were possible with the setup. Graphite cylinders were used as a (potential) membrane. The alternative reactor approach, based on an integrated carbon catalyst cartridge for phosgene generation, was driven up to a successful proof of principle, i.e. reproducible and selective DPC formation via in situ generated COCl2. Technical challenges encountered during experimentation were caused by geometrical limitations in the setup used (responsible for low gas flows), PhOH penetration into the carbon cartridge (deactivating the carbon catalyst) and adsorption of significant fractions of the Cl2 introduced during a typical experimental time on the activated carbon (reducing DPC yield).
In terms of integrated reactor for in situ COCl2 synthesis and immediate conversion (to DPC), different options were analyzed to identify the preferable configuration. Patents for novel recator configuration were filed.
Basic techno-economic assessment of integrated reactor concept
The production of DPC in a reactor fed with carbon monoxide and chlorine besides phenol was demonstrated. In order to assess the impact of the new reaction and reactor concept it is important to investigate the impact of reaction conditions on all process steps required to build a complete DPC process plant. One important aspect would be the cost for phenol separation from the product. Selectivity is another important issue. The reactor modelling was performed for a 20kt DPC system. The proof of concept was demonstrated successfully. Safety assessments took place required to run the lab system.
Phosgene-free DPC synthesis
The activities are to: (i) design efficient water and methanol removal units to minimize the thermodynamic limitation in the DMC and DPC synthesis; (ii) develop stable and selective catalysts for the DMC and DPC synthesis; (iii) study the complex reaction network and establish structure-activity correlations; (iv) study experimentally the influence of critical process parameters.
Between the spects investigated:
1. Synthesis and characterization of various supported MoO3 and TiO2 mixed-oxide catalysts, to find an adequate selective catalyst for the DPC production from DMC and phenol, and to identify main reaction pathways on which DPC is formed.
2. Detailed kinetic and mechanistic studies, to understand complex reaction network
It should be finally mentioned that all expected Deliverables were produced in time.
Potential Impact:
Overview
The expected final project impacts are to develop:
1. new approaches in process intensification through a novel concept of multiphase nanoreactor design,
2. new approaches in multifunctional catalyst design by integrating catalyst and membrane functionalities in an approach aimed at process intensification,
3. new approaches for intrinsically safer design for reactions involving risky reagents.
The expected final result of the project is to verify to applicability and scalability of new concepts in catalysis related to the development of novel nanoreactors and related catalysts for the two listed target reactions and how they can improve (in these industrially-relevant multistage reactions) process intensification, sustainability (in terms of resource and energy efficiency) and safety of operations. Functional to this general objective are the development of catalytic nanomembranes, and of the associated novel reactor concepts. Due to challenging objective of developing novel nanoreactor concepts, the demonstration activities in the project are limited to the proof-of-the-concepts.
In line 2 the expected impacts are achieved, with a new type for scaled reactor for intrinsically safer design, new more active and stable catalysts developed, relevant knowledge/catalysts for alternative processes. Further research, however, is needed to exploit these results.
In line 1 the integration between the two stages, even if many different configurations have been explored, has been not proven successfully. However, project results in this line showed new concept of ceramic hollow fiber reactor which are relevant and innovative for a new process of direct H2O2 synthesis, solving potentially issues of current approaches – autoclave, fixed bed, microreactors – that have inhibited commercial direct H2O2 synthesis. In the integrated process approach, progresses and new advances have been made in membrane reactor modelling, in preparing multicomponent membranes and in understanding role of gradients on performances.
These results indicate the need to extend current examinations and consider further alternatives in process design, in particular regarding alternative heat removal solutions, membrane optimization from modeling, alternative reactors as hollow fiber, etc. Some of the results development within the project may also be exploited outside the project specific field. In addition, the research was proven quite successful in having a decisive impact to SMEs involved in the project to overcome general crisis and open new markets. Therefore, research in this line has generated new knowledge and concepts which translate (later) to innovation.
In terms of dissemination, the following activities have been presented and uploaded on the web site and on the Participant Portal:
- 28 posters
- 16 oral communications
- 18 publications and about other 10 in preparation
3 patents have been prepared. All these 3 patents have not been published yet and for this reason they could not be uploaded on the Participant Portal
Analysis of the impact
In terms of impact, different results have been obtained in lines 1 and 2, as indicated above. In line 1, there is still the need to further develop the materials and process. Actual techno-economic assessment was based on assumptions that need to be revised. Nevertheless, interesting materials in particular and nanoreactor configurations have been developed, which may be later exploited. In particular:
- novel concept of ceramic hollow fiber reactor which are relevant and innovative for a new process of direct H2O2 synthesis, solving potentially issues of current approaches – autoclave, fixed bed, microreactors – that have inhibited commercial direct H2O2 synthesis
- progresses and new advances have been made in membrane reactor modelling, in preparing multicomponent membranes and in understanding role of gradients on performances.
- novel multilayer-type tubular membranes
- novel flat-type AAO nanomembranes functionalized with nanoparticles, which may be utilized also for other type of applications such as in water purification and desalination
- novel type of anodising aluminum foams as scaled flat-type catalyst/membrane systems having higher mechanical robustness.
The list of results with exploitable foreground reports for line 1 seven results going from design of advanced reactor prototype to deposition method of nanoparticles within structured materials (foams, membranes) and new POSS catalysts. The possibility of PO production using the tubular membrane reactor is also under discussion, including regarding patentability. A patent has been issue by one of the partners (a SME) on the synthesis of POSS catalysts.
In line 2, both new catalysts, carbon membranes and new process configurations with membrane reactor have been successfully developed. The list of results with exploitable foreground reports for line 2 thirteen entries, going from new carbon-type and non-carbon-type catalysts to the novel reactor configuration (covered by two patents) and process.
The polycarbonate production capacity worldwide in 2012 was estimated to be about 4.7 million tons. The vast majority (about 80%) of capacity installed is phosgene based. Only a smaller portion (ca. 11%) of the phosgene based polycarbonate processes uses DPC as intermediate. In 2012 capacity installed exceeded demand. While demand for polycarbonate is growing worldwide several companies have announced projects for installation of additional capacity. At the current technical status of the project it is too early to be able to assess the likelihood of implementation of this particular reactor concept/system in future polycarbonate production plants. More detailed investigations of all aspects of DPC production are necessary, i.e. downstream processes. The potential will then depend on the general growth rate of the polycarbonate market and the economics of the competing processes at the locations of the future. Other important aspects are which of the companies operating worldwide will have access to the technology and at what cost/license fee.
Within the scope of the project, the production of DPC in a reactor fed with carbon monoxide and chlorine besides phenol was impressively demonstrated. However, an economic assessment of this new process step requires information beyond the results obtained so far. In particular, in order to assess the impact of the new reaction and reactor concept it is important to investigate the impact of reaction conditions on all process steps required to build a complete DPC process plant. One important aspect would be the cost for phenol separation from the product. Therefore a separation column should be installed. Its size is a direct result of phenol excess. Low phenol excess requires low energy for a later phenol separation step. The higher the phenol excess, the larger equipment size is required not only for the reactor but also for the following work-up.
Selectivity is another important issue. Could phosgene formation in the reactor lead to a different number or type of impurities? The first results of INCAS demonstrator are very promising, since minimal amount of byproducts have been observed.For an initial estimate of the economic potential the following cases could be compared regarding the invest cost:
A: Invest cost for a “stand alone” phosgene production unit plus a reactor of the size and running conditions with 4 fold phenol excess and
B: Invest cost for the newly developed reactor design with installed interior, in particular the required number of tubular membranes
The apparent delta to be considered regarding the reactor includes:
The number of required tubular membranes multiplied by the cost of each tube and the lifetime factor of the catalyst. While there is information available on the cost of graphite tubes, the additional cost for their installation in the reactor is still to be determined. The tube lifetime is assumed to be as long as that of the typical phosgene catalyst due to the same material and operating conditions. The exchange of a membrane tube is an issue since it requires the shutdown of the whole DPC plant and should be taken into account.
Considering invest cost estimates published by SRI consulting in their PEP yearbook 2010 for phosgene production units suggests that combining in situ phosgene generation and reaction with phenol appears economically favorable from an invest cost point of view. However, further detailed analysis of a complete DPC production process including e.g. separation of excess phenol, analysis/separation of side products is required to provide a meaningful economic assessment.
Regarding engineering (basic flowsheet, operation conditions, targets for scaling-up, safety, energy and material balance, process integration), available documentation was included in the technical part. The reactor modelling was performed for a 20kt DPC system. Experiments were conducted at lab scale size. Safety assessments took place required to run the lab system. The proof of concept was demonstrated successfully.
Regarding opportunities. About 16% of the worldwide phosgene consumption in 2013 (CEH report phosgene 2013) was used in polycarbonate production plants around the world. While the proof of principle and reactor design for in situ phosgenation was demonstrated and described for the reaction step in the production of DPC, the key principle and reactor could potentially be successful for other phosgene using production porcesses, too.
Currently, the new INCAS concept is being proposed and assessed as an alternative to the existing phase separation process used for DPC synthesis. The in-situ phosgene generation allowing for sparing the reactor block(s) for phosgene synthesis seems attractive at first view. Opportunities among other companies are also investigated for pursuing an INCAS device where in-situ phosgene is available to activate any secondary reaction.
3 patents have been prepared, of which:
1) Application reference: DExxxxxxx (translation from German: ≈ Process for phosgenation of hydroxy, thiol, amino and/or formamid functional groups containing compounds)
2) Application reference:DExxxxxxx (translation from German: ≈ Process for phosgenation of hydroxy, thiol, amino and/or formamid functional groups containing compounds)
3) Application reference: EP 13190500.2 Synthesis and use of polyhedral oligomeric
silsesquioxane catalyst compositions
All these 3 patents have not been published yet; the URL is not available and for this reason they could not be uploaded on the Participant Portal
4 publications have been submitted but not yet accepted and published, and 2 are still in preparation. For this reason they could not be uploaded on the Participant Portal. Here is the list.
The 4 submitted are:
1) “Adsorbate-induced restructuring of metal NPs”
Payam Kaghazchi, Timo Jacob, Cristina Popa, Tianwei Zhu, Emiel J. M. Hensen - Faraday Discussions
2) “ Structure of Palladium Nanoparticles under Oxidative Conditions”
Cristina Popa, Tianwei Zhu, Ionut Tranca, Payam Kaghazchi, Timo Jacob, Emiel J. M. Hensen – submitted to PCCP
3) “Direct synthesis of propene oxide from propene, hydrogen and oxygen in a catalytic membrane reactor”
Emila Kertalli, Dulce M. Perez Ferrandez, Jaap C. Schouten, T. Alexander Nijhuis
4) “Bent carbon surface moieties as activate sites on carbon catalysts for phosgene synthesis: a model study using C60”, A. Pashigreva, N. Gupta, W. Song, C. Diedrich, E. Hensen, L. Mleczko, E. Ember, S. Roggan, J. Lercher. Angewandte Chemie International Edition - Wiley-VCH.
The 2 in preparation are:
1)“Propylene oxide synthesis in acidic conditions”
Emila Kertalli, Lucas. S. van Rijnsoever, Violeta Paunovic, Jaap C. Schouten, T. Alexander Nijhuis
2) “Experimental and computational investigation of H2O2 decomposition pathway on Pd, PdO catalysts in the presence of H2 and C3H6”
Tao Chen, Emilia Kertalli, Kevin Calloway, Jaap Cornelius Schouten, Tjeerd Alexander Nijhuis, Simon Podkolzin
7 publications are in preparation in collaboration between TUM and BAYER.For this reason they could not be uploaded on the Participant Portal.Here is the list:
1) “Reversible chlorine activation processes on model carbon materials”, A. Pashigreva, N. Gupta, B. Felkel, W. Song, C. Diedrich, K. Metaxas, E. Hensen, L. Mleczko, E. Ember, S. Roggan, J. Lercher. Chemical Communications - Royal Society of Chemistry
2) “Nitrogen and oxygen modified carbon nano-materials as stable non-metal catalysts for transient phosgene synthesis”, N. Gupta, E. Ember, J. Lercher, S. Roggan, L. Mleczko. Angewandte Chemie - Wiley-VCH.
3) “Effect of thermal and O2 treatment on the carbon catalysts performance”, N. Gupta, E. Ember, J. Lercher, S. Roggan, L. Mleczko. Applied catalysis A: General – Elsevier.
4) “ɣ-Al2O3 catalyzed Cl2 activation and COCl2 synthesis”, N. Gupta, E. Ember, J. Lercher, S. Roggan, L. Mleczko. ChemCatChem - Wiley-VCH
5) “Comparative study of Al2O3- and MgO- modified ZrO2 catalysts on dimethyl carbonate formation from methanol and CO2”, B. Peng, E. Ember, J. Lercher, S. Roggan, K. Metaxas, L. Mleczko. Green Chemistry - Royal Society of Chemistry.
6) “Development of stable and efficient catalysts for the DPC synthesis”, B. Peng, E. Ember, J. Lercher, S. Roggan, L. Mleczko. Applied catalysis A: General – Elsevier.
7) “Synthesis, characterization and test of highly efficient zeolitic sorbents for the separation of binary H2O/MeOH and MeOH/PhOH mixtures”, B. Peng, E. Ember, J. Lercher, S. Roggan, L. Mleczko. Journal of Molecular Catalysis A: Chemical – Elsevier
2 more publications in preparation, (not uploaded on the participant portal) are:
1) “Preparation and permeation properties of novel α-alumina tubular composite membranes by consecutive deposition of palladium thin layers and TS-1 nanocrystals” A.Prieto M. Palomino, U. Díaz, A. Corma, S. Abate, S. Gentiluomo, S. Perathoner and G. Centi (ITQ-CSIC/INSTM)
2) “Bi-functional Pd/Au@TS-1 catalysts for direct propylene epoxidation production through in-situ generated H2O2 in supercritical conditions” A. Prieto, M. Palomino, U. Díaz, A. Corma (ITQ-CSIC)
Strategic impacts
The general objective to provide a strategic advantage and added value to society, in terms of competitiveness, reduction of environmental footprint and industrial safety may be difficult to be reached by developing an alternative safer reagent or feed-stock (the classical example of substituting phosgene), or a synthesis methodology (the other classical examples of using supercritical CO2 or ionic liquids instead of the common sol-vents). The quantitative potential impact of these approaches is limited and not in line with the expected impact, as well as limited their pushing role towards a major change in sustainability of the chemical production, e.g. they have a minor effect in providing a strategic advantage as requested in the initial call. The changes in macroeconomic scenario and in society demands require, on the other hand, to really progressing in the development of new enabling mechanisms towards sustainability. For a "strategic advantage" it is necessary to provide new mechanisms for designing the industrial chemical processes, for example which enable a parallelized multi-modular design.
Therefore, the project expected impacts can be summarized as follows:
- A new approach in process intensification through the novel concept of multiphase nanoreactor design; this novel design improves of one order of ma-nitude the process intensification with respect to actual microreactor and thus of about two-three order of magnitude with respect to conventional reactors.
This novel concept enables an improvement in resource efficiency (energy) of over 25-30% with contemporaneous lowering of the costs, and waste production, and improves safety of operations.
- A new approach for intrinsically safer design for reactions involving risky reagents, with a nanoreactor design with integrated transient generation of the reagent (phosgene, in our case). This design also allow to operate the phosgenation in gas phase, and thus solvent-free operations, with great benefits in terms of quality of the product (avoided chlorinated byproducts) and reduction of over 20% in energy costs.
The results of INCAS project showed that for line 2 these strategic impacts can be considered to be met, as indicated before, although further experimentation would be necessary to develop the developed technology to implementation. In line 1, some promising results have been obtained, but there is the need to further develop the concept.
It should be remarked that all the studied reactions are of great industrial relevance. The reaction of clean phosgenation (e.g. with transient generation of phosgene) for DPC synthesis is another illustrative example of the approach used in this project. As commented before, it is better to reduce the risk of using phosgene, instead of finding novel phosgene-free processes or phosgene-substitutes, to improve the sustainability in several industrial processes of synthesis of large-volume chemicals (DPC - diphenylcarbonate, isocyanate and polyurethanes), and fine and specialty chemicals production (active pharmaceutical in-gredients, Taxol, Prodrugs, Agrochemicals, etc.). After about 20 years of effort, the majority of production is still based on phosgene. It is thus preferable to invest on a new intrinsically-safe technology as that proposed in this project. The large involvement in this project (many person/months) of a company world leader in this sector testifies that they believe that the proposed novel technology could have a major impact in this area.
List of Websites:
www.incasproject.eu
INCAS general objective is to provide new tools for process intensification and enhanced selectivity by catalysis. In addition, the methodologies facilitate safer and more energy-efficient production routes. Higher-yield, cleaner and more resource-efficient synthesis of large volumes of chemicals will be a benefit not only to the process routes highlighted but also to applications including fine chemical production and environmental clean-up or remediation. Finally, the project will provide a much-needed framework to analyze the sustainability of various manufacturing processes.
INCAS project concept to promote a sustainable chemistry and more eco-efficient chemical syntheses is to integrate nanoreactor, membrane and advanced catalytic concepts for two types of industrially relevant processes:
• line 1: the direct synthesis of H2O2 and its in-situ use in propene oxide synthesis;
• line 2: the safer synthesis of diphenylcarbonate (DPC).
The aim is to increase efficiency with a reduced number of unit operations via process integration. The concept goes beyond state-of-the-art microreactors that employ microchannels to confine chemical reactions and enhance speed, yield and safety. It exploits nano-size channels and an ordered sequence of catalytic sites along the axial direction of those channels in a membrane providing a vectorial pathway for multi-site catalytic reactions. The concept applies to reactions (as those indicated above), where cascade processes are not possible or not effective.
The use of nano-designed catalytic membrane for transient generation of risky intermediates will go beyond the on-site/on-demand production concept for safer operations. Toxic reactants produced as a result of transformations are immediately converted into harmless entities to completely eliminate storage, which is minimized but not eliminated in on-site/on-demand microreactor production concepts.
The project Consortium to achieve these challenging objectives is formed from 11 beneficiaries, 6 of which are companies, 4 research & education Institutions and one a non-profit research association.
The project final expected impacts are to develop:
i. new approaches in process intensification through a novel concept of multiphase nanoreactor design,
ii. new approaches in multifunctional catalyst design by integrating catalyst and membrane functionalities in an approach aimed at process intensification,
iii. new approaches for intrinsically safer design for reactions involving risky reagents.
The final result of the project was to verify the applicability and scalability of new concepts in catalysis related to the development of novel nanoreactors and related catalysts for the two listed target reactions and how they can improve (in these industrially-relevant multistage reactions) process intensification, sustainability (in terms of resource and energy efficiency) and safety of operations. Functional to this general objective was the development of catalytic nanomembranes, and of the associated novel reactor concepts and engineering. Due to challenging objective of developing novel nanoreactor concepts, the demonstration activities in the project were limited to the proof-of-the-concepts.
In the first two years the focus was on the lab-scale experimentation to develop and tests the reactor concepts, while in the 2nd part of the project the activities were centered on one side on the specific investigation of the performances of the nanoreactors in the two lines of activity and from the other side on the investigation of the issue of scaling the catalyst/membrane and nanoreactors.
Project Context and Objectives:
Promoting a sustainable chemistry and more eco-efficient chemical syntheses requires new efficient tools and working examples, which catalyze the transformation of the energy- and capital-intensive industrial chemical production. A key factor to foster this change is to develop integrated eco- and energy-efficient syntheses, which imply the capacity to innovate in the field of process intensification, a key for industrial competitiveness, improved use of resources, reduction of the amount of waste and emissions, as well as better safety.
The project context is to address these challenging objectives by integrating nanoreactor, membrane and advanced catalytic concepts. The key concept is the use of nano-designed catalytic membrane for transient generation of risky intermediates, going beyond the on-site/on-demand production concept for safer operations.
The other key concept is to have a step-forward in the integration of microreactor technology with catalysis, two of the crucial pillars to foster a sustainable industrial chemistry. They are key components of process intensification to transform from energy- and capital-intensives to safer and eco-friendly processes, with positive impact also on the competitiveness of chemical industry.
A solution is a modular process design, based on the concept of parallel reaction units, as opposite to scale-economy approach used currently in the chemical industry. Between the advantages:
(i) Safety: less storage and/or transportation of hazardous materials, reducing the likelihood of accidents, and any accidents that do occur will be smaller and less catastrophic. Possibility of realize a delocalized and on-time production.
(ii) Cost and time in introducing new processes: capital costs, transportation costs, and inventory costs are all lower. Easier introduction of new processes on smaller scale; productivity can be increased later by adding new units. Faster time from discovery to industrial production. Easier customization.
(iii) Cycle avoidance: existing large plants consistently suffer from over- and under-capacity scenarios, leading to typical boom-bust cycles.
This new approach requires a next step in an integrated microreactor and catalyst design. In fact, a key aspect for success, and a reduction in energy and capital intensity, is to realize in a single unit complex multistage processes. This is a key for safer and environmental-friendly operations, because there is a reduction of the stages with consequent decrease in energy consumption and waste generation, and the elimination of the storage of possible dangerous intermediates. The approach typically used in microreactor technology is the miniaturization of the reactor and other unit operations, to make compact devices where the reduction of mass and heat transfer leads to process intensification. However, the real potential of using this technology to realize in a single unit complex multistage reactions has been scarcely investigated, because requires a further step in an integrated microreactor and catalyst design, the core aspect of this proposal.
Usually, microreactors have channels in the micrometer diameter range (around 100-150 micron), while the more effective integration between microreactor and catalysis require developing reactors with channels of nanometric size. They are interesting also in general terms, because would further increase of one-two order of magnitude the possible process intensification. In terms of safety, the passage from micro- to nano-reactor would bring several benefits. It is known that the higher wall-to-volume ratio in microreactors with respect to conventional reactors, allows to effectively quenching radical-type reactions and runaway effects. In nanoreactors, the further increase of one-two order of magnitude in the wall-to-volume ratio will further increase safety of operations, allowing, for example, operating without risks inside the explosion region, or with highly exothermic reactions. The integration between nanoreactor and catalysis is thus a key factor towards scientific and technological breakthrough in synthesis for a sustainable chemical production.
The use of catalytic membrane as nano-reactor offers a further possibility to implement novel concepts for safer industrial syntheses. Phosgene is central to the chemistry of pharmaceuticals, polyurethanes, and polycarbonates; a huge market sector generating 8 million tons of products. Phosgene, however, is a highly reactive chemical, and very toxic (TLV = 0.1 ppm), and its manufacture poses serious problems. For this reason, from about two decade there is a large effort in finding safer substitutes such as DMC. Despite these concerns, 5–6 million tons y-1 of phosgene are still produced and used worldwide, while a greener substitute such as DMC has a market about 20-25 times lower, due to techno-economic reasons. From the industrial perspective, the effort has been thus mainly directed towards a safer use of phosgene (on-site or on-demand production) more than to its substitution. The use of catalytic membrane allows to further progress in this direction, implementing the concept of ‘‘dynamic nanoreactors’’ where phosgene is produced and immediately converted in the phosgenation reaction. We indicate this concept as transient phosgene generation. The storage of phosgene is eliminated, and the amount of toxic chemicals becomes negligible. Reduced dimensions allow also confinement of the reactor and supply system, further minimizing the risks and possible leakages.
The project vision for safer and sustainable industrial chemistry is thus centered on these aspects:
(i) to realize efficient modular-design of industrial chemical synthesis, also for large-scale processes, as a decisive factor to accelerate the introduction of novel processes, and enhance competiveness;
(ii) to progress with respect to actual microreactors as necessary step to move in this direction and realized by integrating nanoreactor, membrane and advanced catalytic concepts;
iii) to utilize this novel design as a key element to improve safety, as more effective (time, cost) to accelerate the transition to a safer and sustainable industrial chemistry with respect to redesign the process using alternative reactants requiring large investments costs.
Project main objectives
The project aims is to explore, with reference to the two keys industrial processes listed below
• line 1: the direct synthesis of H2O2 and its in-situ use in propene oxide synthesis;
• line 2: the safer synthesis of dyphenilcarbonate DPC via in situ synthesis of COCl2
the possibility to achieve more efficient processes with a reduced number of unit operations by realizing process integration through the use of novel nanoreactors concepts. The aim is to increase efficiency with a reduced number of unit operations via process integration. The concept goes beyond state-of-the-art microreactors that employ microchannels to confine chemical reactions and enhance speed, yield and safety. It exploits nano-size channels and an ordered sequence of catalytic sites along the axial direction of those channels in a membrane providing a vectorial pathway for multi-site catalytic reactions. The concept applies to reactions (as those indicated above), where cascade processes are not possible or not effective.
The general objective of INCAS project is to provide new tools for process intensification and enhanced selectivity by catalysis. In addition, the methodologies facilitate safer and more energy-efficient production routes. Higher-yield, cleaner and more resource-efficient synthesis of large volumes of chemicals will be a benefit not only to the process routes highlighted but also to applications including fine chemical production and environmental clean-up or remediation. Finally, the project will provide a much-needed framework to analyze the sustainability of various manufacturing processes.
The use of nano-designed catalytic membrane for transient generation of risky intermediates will go beyond the on-site/on-demand production concept for safer operations. Toxic reactants produced as a result of transformations are immediately converted into harmless entities to completely eliminate storage, which is minimized but not eliminated in on-site/on-demand microreactor production concepts.
The project has highly challenging objectives, because no proof of the concept of the possibility to implement these concepts was available at project start. It also has many materials challenges, for example in realizing (nano)membranes, their scale-up, in development (nano)carbon materials for phosgene synthesis, etc. Finally, many technical challenges were also present: how scale-up reactors, design of (nano)-reactors, catalysis in membrane interface. As a consequence of this high risk/high gain project, the project objectives evolved during the project, although maintaining the focus on the general project aim.
Project Results:
The project structure is organized in four main scientific WPs, plus one WP dedicated to dissemination and exploitation of the results and one WP project management and coordination. The main objectives for the core scientific WPs were the following:
WP1: prepare reliable catalytic nanomembranes to be used in the nanoreactors for the H2O2 direct synthesis, PO synthesis with integrated H2O2 generation and DPC synthesis via in situ synthesis of COCl2.
WP2: assemble, test and optimize the nanoreactors for the H2O2 direct synthesis, PO synthesis with integrated H2O2 generation and DPC synthesis with integrated COCl2 generation.
WP3: use the catalyst/membrane and nanoreactors developed in WP1 and WP2, and tests in the reactions of H2O2 direct synthesis, and PO synthesis with integrated H2O2 generation.
WP4: use the catalyst/membrane and nanoreactors developed in WP1 and WP2, and tests in the DPC synthesis with in-situ transient generation of phosgene.
Some of the key results obtained in these WPs are the following:
In WP1: i) produced, characterised, modified and assessed AAO (anodic alumina oxide) membranes, ii) synthesised and deposited Pd nanoparticles for catalyst substrates, iii) synthesised carbon-based membranes and zeolite coated systems, iv) engineered testing equipment facilities, v) modelled substrate and catalyst system configurations, vi) reviewed, identified and progressed alternatives e.g. tubular ceramic
In WP2: i) developed flat-type nanoreactor for line 1 as well as tubular-type membrane (nano)reactor, ii) fabricated mock-up prototype, iii) developed hollow-fiber modules for scaling-up reactor in line 1, iv) developed membrane reactors to work in gas-liquid and gas-gas phases, v) simulations of the membrane model for the phosgene synthesis + phosgenation of phenol to diphenyl carbonate (DPC) , vi) design of the prototype reactor for line 2 vii) fabrication of the reactor-prototype for line 2
In WP3: i) tested different reactor configurations and combinations of multilayer membranes, ii) analysis of the different feeding possibilities to operate in safe conditions, iii) scale-up and testing of hollow-fiber configuration, iv) patentability analysis.
In WP4: i) understanding the mechanism of COCl2 formation over carbon catalyst, particularly what are the active sites on the carbon catalyst surface and what is the nature of the transient intermediates, ii) understand the mechanism of deactivation, expecially what triggers deactivation of carbon catalysts and identification of the measures to avoid deactivation / regeneration, iii) identification of stable catalysts and of alternative, non carbon catalysts, iv) design and performing a lab-scale demonstrator, identification of the concept for scaled reactor and application of insight gained for current COCl2 manufacture. In terms of integrated reactor for in situ COCl2 synthesis and immediate conversion (to DPC), different options were analyzed to identify the preferable configuration.Patents for novel recator configuration were filed.
WP5 was related to project dissemination and exploitation. Several publications and presentations at conferences resulted from the project, 3 patents, and a list of exploitable items. Between the activities made: i) maintenance of the website for public and inside consortium activities, ii) presentation of the project’s results and activities during the project’s meetings, iii) drafting and maintaining the dissemination and exploitation plan following the EC’s requirements, iv) establishing the actions for dissemination and exploitation, v) organizing and managing the activities of the Exploitation Committee for protecting the project results, vi) continuous monitoring of the progress of the research within the project to verify which results (a) should be protected by patents and (b) are relevant to exploitation in fields outside the specific scope of the project, take all the actions necessary for successful exploitation of the results of the project.
WP6 was related to project management and coordination. Between the activities made: i) realization and implementation of a coherent and efficient project management and co-ordination of the project in accordance with the budget and the schedule of milestones and deliverables; ii) design and implement the management tools necessary for an efficient and timely project management. In addition to preparing the various contract report and meeting, as well as maintenance of the communication and exchange with the European Commission, it was implemented a continuous monitoring the status of the project’s deliverables and milestones, the handling of legal issues, IPR issues and maintenance of the consortium agreement, the management of knowledge generated by the project and the handling of the project correspondence and the day-to-day requests from partners and external bodies.
Selected main S&T results
Synthesis, characterization, modification and assessment of membranes
The first two years of the project were focused on catalyst/membrane preparation for lab-scale tests while later the effort was directed towards scaling of the catalyst/membrane. Ultimately such membranes were evaluated for their performance as nanoreactors in H2O2 direct synthesis, PO synthesis with integrated H2O2 generation and DPC synthesis with integrated COCl2 generation.
During the first 24 months of the project, more than three basic membrane types have been produced: several with straight-through vertical porous channels and several with mesoporous structures. Two types of membrane with vertically-aligned straight channels have been generated by anodizing either titanium or aluminum: these are generally referred to as anodic titanium oxide (ATO) or anodic aluminum oxide (AAO) membranes. The mesoporous membranes (i.e. no straight-through porous channels) have been prepared by either polymerising siloxanes, TS-1 or with carbon powder.
Initially 60 x 40mm AAO membranes with a capacity to produce 2-4 membranes of this size daily, due largely to the anodizing protocol employed requiring a 2-hour dwell time and constant current and voltage conditions, were prepared. The electrolyte used in the production of AAO membrane types is a mixture of phosphoric and oxalic acids and a carbon counter-electrode. Samples of these types of AAO membranes have been supplied to the relevant partners for their further characterization, modification and assessment.
In parallel, planar ATO membranes (by anodising titanium foil) were also prepared (size about 3 cm diameter). However, this type of membranes lacked a sufficient degree of mechanical or dimensional stability to be employed effectively with the project as a catalyst support material in a reactor assembly. In addition, these ATO membranes adversely affected hydrogen peroxide decomposition.
Novel synthetic routes for both carbon-coating membranes and producing carbon monolithic membranes were also investigated, because the tested commercially available C membrane materials lack of the necessary characteristics. One of the preferred route to prepare these C membranes involves starting from powder type nanocarbons , process in solvents and then cast onto glass plates at room temperature prior to vacuum oven treatment.
POSS (Polyhedral Oligo SilSesquioxane) membrane materials, that are both completely and incompletely condensed variants through different synthesis routes, were also synthetized as well as TS-1 membranes were synthetized and assessed.
Synthesis and deposition Pd nanoparticles for catalyst
Nanoparticle synthesis. In order to identify suitable synthetic methods for the production of palladium nanoparticles started from a review of the open literature. By using H2PdCl4 and PVP, palladium nanoparticles with a narrow particle size distribution and, in the size range desired <5nm diameter, were obtained. A consistent a reproducible synthesis protocol for palladium nanoparticles has been achieved with initial problems identified and resolved. This procedure has been used in all subsequent experiments with palladium nanoparticles
The deposition of palladium nanoparticles on membrane was initially attempted by dropping the palladium nanoparticles solution on the membrane and allowing the solvent to evaporate, but this method proved inconclusive in terms of the deposition of the particles as the amount was too low. After evaluation of different variations on the method, and the investigation of alternative methods such as by homogeneous deposition precipitation (HDP; a solvated metal precursor is deposited on the support surface by the slow and homogeneous introduction of a precipitating agent, generally hydroxyl ions), a method by ligand exchange was adopted. A modification of this method regarded the ligand functionalization of AAO membrane. A specific novel apparatus was introduced to avoid the generation of gradients in nanoparticles. The methodology allowed to produce a consistent and reproducible protocol for palladium nanoparticle deposition on the AAO membranes to prepare samples with uniform and concentrated deposition of the nanoparticles throughout the membrane. The novel catalytic membranes showed good stability.
Synthesis of carbon-based membranes and zeolite coated systems
Carbon coated AAO alumina membranes were investigated. However, a major problem derived from the need to avoid from one side to completely block, or significantly alter the AAO nanomembrane porosity, and from the other side to avoid rupture of the membrane particularly during the annealing procedure. Two types of preparations (differing in the type of carbon-precursor) were selected by using two different precursors for the carbon: glucose and triton X-100. After pyrolysis at 250°C, the best results were obtained with the Triton X-100, where during decomposition the Al2O3 membrane doesn’t stress and the overall appearance was smooth and homogeneous. Permeability tests, as well as characterization of the surface roughness, confirmed that the membranes are suited for testing.
Self-supported carbon membranes were also prepared and evaluated. The method developed consisted in the physical mixture of a carbon powder with an epoxidic resin, co-adding high surface area SiO2 or Al2O3 as “hierarchical agent”. In fact, further dissolution of them by HF, confers the introduction of higher porosity to the composite. This method is particularly advantageous for several reasons:
i) The carbon powder source can be selected: we chose to test a particular carbon onion-like structured, because it seems to be active for the phosgene synthesis. Alternatively, any kind of carbon powder can be added.
ii) The membrane does not need the use of a support: the resin acts as self-structuring agent.
iii) The membrane is mechanically and thermally resistant: the HF attack and the treatment at 220°C generate a stable structure.
iv)The size of the membrane can be easily tuned: since the moisture Carbon/resin/HA is fluid, it can be placed in a specific mold in a way to obtain the desired shape.
The choice of the carbons to incorporate in the membrane was given by the experience of carbon materials used in the COCl2 synthesis. So, as carbon precursor a “onion like” carbon prepared within the project and a carbon supplied from one of the partners were used for membrane preparation.
Characterization techniques and gas permeability tests showed the good accessibility to inner core of membranes. These membranes were utilized in the catalytic tests.
TS-1 membranes. Different deposition procedures to obtain improved alumina membranes supported with thin TS-1 layers were investigated. Thick TS-1 membranes (125μm) through direct in situ synthesis of TS-1 nanocrystals onto AAO membranes were initially prepared. The method was later optimized to produce TS-1 layers with much reduced thickness (35μm). Further studies have carried out high temperature treatments with the TS-1 supported membranes to study their hydrothermal stability and the results showed that no cracks are observed after calcination to 550ºC but the membrane was curved. Following this initial membrane synthesis work, further studies focused on two different approaches: using standard and polymer assisted dip-coating methods. These latter studies have been performed with AAO membranes and the results obtained have shown that the TS-1 seeding was more effective when a polymer electrolyte was employed.
Modelled substrate and catalyst system configurations and engineered testing equipment facilities
For an optimized concept of the membrane nanoreactor, the steps in the reaction need to be de-coupled. In line 1, first H2O2 has to be in situ generated over Pd catalyst and then diffuses over titanium silicalite-1 for the further reaction with propene to produce propylene oxide. The limiting step of the overall reaction (H2O2 production) is taking place in the membrane itself where H2 and O2 are fed over the channels of the membrane. Since hydrogen peroxide is a chemically instable compound due to fast decomposition over different types of materials, this limits the material choice for the membrane. The first requirement has then to ensure that no (or limit) decomposition of H2O2 over the material occurs. A series of initial studies thus focused on this aspect.
An issue in using the flat-type nanomembranes described above is fragility. A possibility investigated regarded the utilization of a non ordered macroporous oxide support on the top of which deposit the ordered membrane layer that will act as a catalytic one. The second suggestion presents the advantage of overcoming the problem of increasing the thickness that can lead to a mass transfer limitation during reaction operation. In fact, by increasing the thickness one of the most important characteristics of the membrane itself is limited and reduced: the gas permeability. In order to understand the performance of the membrane, permeability tests were conducted. Also with suitable modeling it was evaluated the minimum value of the membrane thickness needed for catalytic application. The membrane thickness is an important parameter to be integrated with the catalytic requirements from the reaction. A further modeling was utilized to improve the design of the membrane nanoreactor concept and analyze the characteristics for industrial scaling up.
An important element to optimize and scale-up the integrated reactor in line 1 was to develop a modelling approach to determine the optimal characteristics necessary and the potential results. The reactor model deals with a high pressure gas/liquid system. The purpose of the model is the optimization of the reactor concept by knowing the concentration-diffusion profiles of the different reactants and products along the membrane layers. A working model for the direct synthesis of propylene oxide has been developed. The model shows the dependence of H2O2 conversion and selectivity on the membrane parameters such as the thickness. Also the PO synthesis is strictly connected to the first catalytic layer. In order to reach the scaling up requirements, a Pd/SiO2 membrane thickness between 100-250 µm has to be ensured. The model is also available to understand the influence of other parameters such as the gas partial pressures, liquid and gas flow rates and membrane areas in order to further understand the membrane reactor behavior.
In parallel, density functional theory was used to investigate the direct synthesis of H2O2 over Pd based nanoparticles. The aim of the study was to elucidate the reaction mechanisms for H2O2 obtaining on two representative surfaces of an active Pd nanoparticle in reaction conditions: (i) O/(√5x√5)R27o Pd(100) and (ii) PdO(101).
Development of tubular ceramic nanomembranes
Due to issues presented by flat-type membranes, the focus on the last part of the project was on the development of alternative tubular-type ceramic nanomembranes, to utilize for the scale-up of catalysts/membrane, in relation to reactor design identified in other WPs. In line 1, limited robustness of flat-type membranes caused the need to develop alternative tubular-type membranes, but limited performances of the various configurations tested do not allowed to pass to larger scale prototypes. However, it was explored the use of a reactor based on hollow-fibers as scaled-type prototype. In parallel, investigation was related to deposit the catalyst (Pd and TS-1) on tubular membranes as next step in scaling this type of membranes and to prepare and functionalize with catalysts anodising aluminum foams as scaled flat-type catalyst/membrane systems having higher mechanical robustness. In line 2, the activity was in relation to scaling the catalyst/membrane in relation to prototype and model of reactor defined in simulation studies, and to develop the zeolitic membrane for the two-step phosgene-free DPC synthesis.
Procedures to improve Pd dispersion on alumina tubular membrane were developed and the samples characterized in terms of properties and performance. The procedure developed for Pd incorporation was based on impregnation-decomposition method. The membranes produced gave the best performance in H2O2 direct synthesis, a narrower particle size distribution; and no deactivation as had occurred previously with samples prepared by sol-immobilization procedure. Additionally, the effect of different cycles of thermal treatments on the same membrane was evaluated. A second heat treatment led to a narrower particle size distribution, retained the same degree of metal dispersion on the support and provided an improved product selectivity.
The high selectivity observed on the membrane prepared by impregnation-decomposition (D-I) after heat treatments has been explained on the basis of FTIR characterization where it has been observed that more exposure of homogeneous facets (i.e. less defect sites) is a consequence of preferential exposure of the facets (111). Adsorption of reactants on planar sites (111) seems to be the optimal condition to get direct formation of H2O2. This agrees with theoretical modelling results by DFT method.
Membranes by using two preparation technique (sol immobilization and reduction by hydrazine) were prepared to test alternative configurations for palladium arrangements. The scaling of the deposition of TS-1 on tubular membranes, in order to improve the quality and coverage of TS-1 membranes on alumina tubular supports, was also investigated with the objective being to prepare suitable bi-functional catalytic systems Al2O3@Pd@TS-1 for direct one-step PO production from H2, O2 and C3=. A novel type of composite membranes based on palladium thin layers externally coated with TS-1 nanocrystals, using α-alumina tubes as support substrates was prepared.
Important advances were achieved by identification of the need to seed coated Pd films with TS-1 nanocrystals via a polymer dip-coating process followed by a secondary growth step. In this latter case, micellar gel for secondary growth of the seeded supports was investigated and the resulting membrane consisted of a well-intergrowth layer of TS-1 zeolite with a thickness of 0.7 µm. The TS-1 membrane is strongly attached to the palladium film and no peeling was observed. Electron microscopy characterization confirms the effective presence of outer TS-1 layer onto internal palladium film which is coating the tubular alumina supports.
The possibility to obtain a dense zeolitic membrane on the polymer-coated metallic surface by direct growth of the zeolite crystals and without the previous TS-1 seeding deposited by polymer assisted dip-coating was also analyzed. A densely packed TS-1 membrane was grown on the palladium surface, although visible discontinuities were detected.
Scaling the tubular-membrane approach to develop hollow-fiber reactor
Scaled-up nanoreactor (line 1) was based on the use of hollow-fiber modules. A new reactor prototype for testing them was assembled. A new scenario for the production of PO could be the use of hollow fiber membranes with a lower wall thickness (0.5 mm) then the previous membranes (wall thickness 1.5 mm). Although as known selectivity in H2O2 is limited for operations at low pressure as in the following tests, the results show that hollow-fiber membranes under the same conditions allow about three-four times higher productivity and selectivity with respect to tubular-type membrane R70 benchmark. The approach is thus well suited for scaling-up performances and intensifies the process.
Scaling the preparation to produce anodising aluminum foams.
A thinner, more open-pored structure on aluminum foam using alternative anodizing conditions (with phosphoric electrolytes) was successfully produced for subsequent catalyst deposition and evaluation: initially film thicknesses of <1µm were achieved but it was considered that these also were likely to be too thick and, consequently, oxalic electrolyte options were produced with anodic film thicknesses of 1-2µm but with very fine pore widths of ~30-40nm.
Further studies were then subsequently undertaken on pore widening options with anodized aluminum foam but, despite the “imperfect” anodic film structures initially grown on the anodized aluminum foam, Pd nanoparticles were deposited successfully within the pore structure. Alternative anodising processes were also explored with the aim of identifying open-pored structures of the “required” structure; one of these is hot AC phosphoric acid processing. This procedure provides an anodic film geometry on anodised aluminum which might be considered closer to product application requirements.
In addition, polymer replication from an anodised aluminium substrate – resulting in the creation of a textured polymeric substrate which may have applicability as a catalyst substrate, was developed.
Scaling the preparation of carbon catalytic membranes for line 2
The scaling of the preparation of carbon membrane (line 2), with the aim to improve the synthesis procedures for C-containing membranes was investigated with a focus on:
• thermal stability up to 300°C
• control of membrane thickness in the range 0.3-0.5 mm
• high permeance
• high porosity
• higher carbon loading
Different types of nanocarbons starting materials were utilized. The results demonstrated that a synthesised variant can show comparable and even better properties to commercial systems.
Scaling the preparation of zeolitic membranes for two-step phosgene-free DPC synthesis in line 2
The scaling of the preparation of zeolitic membranes for two-step phosgene-free DPC synthesis (line 2), one of the most promising alternative pathways for DPC synthesis, was also investigated. In the first step the formation of dimethyl carbonate (DMC) from methanol and CO2 takes place, whilst in the second reaction DMC is converted via transesterification with phenol to form DPC as the target molecule. Both of the reaction steps are highly equilibrium constrained. Therefore, besides rational design of efficient catalysts, the selective product separation (i.e. water removal in the 1st step and methanol removal in the 2nd step) is demanded. In a first attempt, LTA zeolitic wafers were synthesised and thoroughly synthesised prior to membrane growth. Similar the case of DMC, in order to enhance the DPC formation, efficient membranes for the methanol removal from phenol abundant solution are required. Therefore, a similar approach as in the case of water/alcohol separation membranes was applied. For a selective MeOH removal for improvement of transesterification yield was achieved by using newly prepared LTA zeolitic membrane. However, the pore-opening ought to be different as in the case of water removal from alcohol. This modification of pore-opening was fulfilled by different cation exchange.
A continuous-flow reactor with on-demanding product separation has been proposed. At the bottom part of the reactor, the reaction would be initialized by DMC formation from methanol and CO2 (catalyzed by ZrO2-based catalyst), co-produced water would be eliminated simultaneously by membrane made by zeolite. Till DMC yield reach certain high level, transesterification of phenol and DMC would started (catalyzed by MoO3- or TiO2-based catalyst), another zeolitic membrane would be applied for methanol removal. At last, DPC would be obtained with high yield..
Development of flat-type nanoreactor for line 1 as well as tubular-type membrane (nano)reactor, fabricated mock-up prototype, developed membrane reactors to work in gas-liquid and gas-gas phases, design of the prototype reactor
The following types of flat-type nanomembranes have been investigated:
- for line 1,
i) alumina (AAO) nanomembranes of about 25 mm in size produced by Innoval and
ii) titania nanomembranes of similar size prepared by INSTM.
Both were produced by anodic oxidation, but the investigation of the titania type membranes was stopped due to both problems of material compatibility and of preparation (severe curling).
- for line 2,
i) carbon-coated nanomembranes (on alumina substrate) and then coated with carbon.
ii) carbon-only membranes prepared using nanocarbon materials and then converted to the flat membranes by casting procedure after addition of suitable additives.
For testing the characteristics of these flat-type nanomembranes (robustness, sealing, permeability), a simplified mock-up reactor was constructed and used.
A new mock-up reactor prototype was also fabricated to investigate the fluid-dynamics of the gas-liquid contact and mixing using the flat alumina AAO membranes. The reactor is designed to carry out reactions in gas/liquid phase: (i) one side is prearranged to feed gas and the other to feed a liquid flux in continuous mode; (ii) the 2 chambers are separated by the membrane. The reactor was designed to have a minimal thickness for the liquid side (about 1 mm), in order to simulate the original design.
Some of the main conclusions from these activities are the following
Line 1:
- a SS prototype was already fabricated, and two reactors were already sent to partners for testing.
- the decision concerning the scaled-up nanoreactor (line 1) was based on the use of hollow-fiber modules. A reactor prototype for this experimentation was designed, assembled and tested.
- the tubular reactor prototype has also been modified to work in gas-liquid phase conditions. This modification was carried out taking account that the formation of H2O2 intermediate is favored in liquid phase at softer reaction conditions. The apparatus were updated for testing membrane in another configuration; feeding a non-explosive mixture 3%H2-97%O2 through the membrane while in the other side the methanolic solution phase is feed as in the previous tests.
In Line 2:
- the design of the prototype reactor was assessed and the reactor-prototype together with o-ring in kalrez, thermocouple and some carbon based membranes send to partners for testing.
- engineering modeling and safety aspects have been considered for the nanoreactor design. They were also used to consider the carbon thickness necessary and to estimate the heat release, also in consideration of the heat control necessary to minimize deactivation.
- based on the elaborative analysis of the integrated system, the final reactor concept of a multi-tubular reactor was put forward and assessed for its ability to reach a realistic commercial capacity of the targeted product DPC.
Development of hollow-fiber modules for scaling-up reactor, fabrication of the reactor-prototype.
A nanoreactor (and related apparatus) for using hollow-fiber modules was designed and assembled as new scale-up reactor prototype.
Increase in PO performances were studied through the use of further membrane catalytic systems studied considering the influence of the following parameters: use Pd films or nanoparticles (seeds), combination of active layers in different order such as Pd@TS-1 or TS-1@Pd membranes, passivation of acidic external groups, increase in the content of active phase and reactions with high oxygen regimes, i.e. using non-explosive H2-O2 mixtures. All these parameters were considered in membrane reactor suitable to work in gas phase. Furthermore, novel tubular reactor prototypes were assembled to better analyze different reaction variables and increase the PO productivity. For this, liquid-gas reactor proto-type was assembled and optimized to compare with the most favorable reaction conditions to generate intermediate in situ H2O2. Moreover, tubular prototype adapted to work with alumina hollow fibers was also designed and optimized trying to increase the productivity and efficiency of the two-step one-pot catalytic process.
Both approaches (i and ii) are complementary, being the advances achieved in batch catalytic studies useful to be applied in the membrane reactor proto-type tasks.
Tested different reactor configurations and combinations of multilayer membranes,
Different configuration/arrangement of Pd/membrane were tested. The best results in the direct synthesis of H2O2 were obtained with the benchmark configuration giving a better productivity, activity (hydrogen conversion) and selectivity respect to arrangements of Pd on the external side. All the membranes tested shown activity toward hydrogen conversion (H2O productivity), which means that the membranes are completely wetted by the methanol solution. The lower selectivities obtained by the catalytic membranes prepared by external Pd deposition are attributed at the higher hydrogen peroxide retention time in the membrane pores (pore length: 1.5 mm, without taking into account the tortuosity factor) in contact with Pd particles. Similar results are obtained with the membranes prepared by N2H4 reduction technique, where we have also a higher H2O production rate in the case of the external palladium arrangement compared with our benchmark.
We might conclude that the higher concentration locally achieved inside the pores of the membranes prepared by external palladium deposition are detrimental in our experimental condition, but might be a key factor for the PO production. A new scenario for the production of PO could be the use of hollow fiber membranes with a lower wall thickness (0.5 mm) than the previous membranes (wall thickness 1.5 mm).
Higher productivity in the PO synthesis were shown by using a specific type of membrane with the reactor configuration as follows: TS-1 layer deposited on the internal side). Based on this result some membranes by using two preparation techniques (sol-immobilization and reduction by Hydrazine) were prepared.
Four different reaction configurations were investigated for tubular membranes:
- Reaction configuration IA: Pd seeds or film are located in the internal side of the alumina supports, and TS-1 membrane is grown over it. Hydrogen is fed from the outer side of the membrane in gaseous phase at constant pressure (2 bar). Propylene and oxygen saturated methanolic solution is continuously circulated on the inner side by means of a peristaltic pump (25 ml/min).
- Reaction configuration IB: Pd seeds or film are located in the external side of the alumina supports, meanwhile TS-1 membrane is in the inner side. Hydrogen is fed from the outer side of the membrane in gaseous phase at constant pressure (2 bar). Propylene and oxygen saturated methanolic solution is continuously circulated on the inner side by means of a peristaltic pump (25 ml/min).
- Reaction configuration IIA: Pd seeds or film are located in the internal side of the alumina supports, and TS-1 membrane is grown over it. Oxygen and hydrogen are fed together in a non-explosive regime by the outer side of the membrane in gaseous phase. Propylene saturated methanolic solution is continuously circulated on the inner side by means of a peristaltic pump (25 ml/min).
- Reaction configuration IIB: Pd seeds or film are located in the external side of the alumina supports, meanwhile TS-1 membrane is in the inner side. Oxygen and hydrogen are fed together in a non-explosive regime by the outer side of the membrane in gaseous phase. Propylene saturated methanolic solution is continuously circulated on the inner side by means of a peristaltic pump (25 ml/min).
Reaction configurations IIA and IIB forced to work with only 3% of H2 in order to be in a non-explosive regime, resulting in lower H2O2 productions, much higher selectivities. This approach could be an interesting alternative, because its use could significantly reduce the amounts of propane formed, being, in any case, necessary to increase the H2O2 productivity to improve the final PO production. On the other hand, reaction conditions IA and IB lead up to now the best H2O2 production results using this kind of tubular membrane reactors. Configurations IIA and IIB, in which H2 and O2 are feed together, did not lead to any production of propylene oxide. These results agree with the results obtained, which showed a low H2O2 production in both configurations when H2-O2 non-explosive mixtures are used.
When the reactions were carried out with the typical configurations, IA and IB, feeding H2 from the outer side and O2 together with C3H6 in the inner side dissolved in methanolic solution, two different results were observed. On the one hand, membranes in which Pd is in seeds form located in the inner side (R73), the PO production does not exist or is too reduced, with propane being the main product. On the other hand, the membrane with Pd film located in the internal side, led to better catalytic results, methoxypropanols were also observed during the reaction. The results indicate that PO production is favured when Pd seeds in the outer side or Pd film in the inner side are coating the alumina support, always feeding separately H2 and O2.
Conclusions of Tubular Membrane Reactor Tests
- TMR prototype in gas reaction conditions is not effective to produce PO in one-pot process (only PO traces are obtained) due to the complete oxidation of Pd species in the catalytic system.
- TMR prototype is effective to produce PO in one-pot process in liquid-gas conditions when H2 and O2 are separately fed in the reaction system. Specifically, in these conditions, the best performances have been obtained when Pd film or Pd nanoparticles are supported into the internal or external side, respectively, of alumina tubular membrane, in presence of internal TS-1 layer. In these conditions, the stabilization of in-situ generated H2O2 is enough to produce PO in the second reaction step.
- Reproducibility test show a strong dependence with the membrane used in all cases. This issue is still a matter of study.
- Feeding together O2 and H2 (using H2-O2 non-explosive mixtures at high O2 regimes) did not led to PO production in any case, due the poor stability and low productivity of in-situ generated H2O2 under these reaction conditions.
- Process optimization is necessary to increase PO yields, analyzing different parameters such as catalyst amount, incorporation of promoters (Au, Pt, Ag), pressure gradients, reduction of propane formation as main reaction product and use of H2O2 stabilizers among the most relevant matters to be considered in the close future.
Tests in batch reactor were also made. Some of the conclusions are the following:
- Bi-functional Pd@TS-1 catalysts are effective to produce directly PO through one-pot two-step process from H2, O2 and C3=, using supercritical CO2 conditions (high pressures ~ 75 bar).
- Best results are obtained using MeOH as co-solvent, ammonium acetate as acidity inhibitor and C3=/H2/O2 molar ratios close to 1/1/1. Higher selectivity to propane was observed when H2/O2 ratio was higher than 1, resulting in a decrease in the PO selectivity.
- In general, H2O as only co-solvent does not favor the PO production, although its negative effect is strongly minimized in the presence of MeOH, overall when Pd@TS-1 catalysts are used.
- The presence of Au/Pd alloy nanoparticles supported onto TS-1 allows the preparation of effective bi-functional catalysts which are more reactive than only Pd counterparts, achieving C3= conversions of ~15%, and PO selectivities and yields close to 82% and 11% respectively, reducing significantly the propane formation (SC3~10%).
As general conclusions from these tests it may be indicated
- Bi-functional catalytic systems (powder or membrane system), based on Pd species (nanoparticles or films) and TS-1 zeolite (powder or dense layer) are effective for direct PO production from H2, O2 and C3= through in-situ generated H2O2.
- High PO performances are obtained in batch catalytic processes with supercritical CO2 conditions at high pressures and with the additional presence of metallic promoters (Au, Pt).
- Tubular membrane reactor (TMR) prototype is valid to carry out the one-pot two-step process in liquid-gas conditions, using bi-functional Al2O3/Pd/TS-1 membranes, feeding separately H2 and O2 into the reaction system. The stabilization of in-situ generated H2O2 in methanolic solutions, containing saturated O2 and C3=, is necessary.
Engineering of the scaled-up nanoreactor and assessment of the nanoreactor prototypes
Aspects analyzed regarded:
1. The detailed design of the reactor (dimension, shape, manner of heat transfer etc.).
2. The total mass balance of the reactor.
3. The process scheme including operating conditions.
These specifications were derived from and based on the earlier work of the other partners. However, the results of the process in line 1 are highly depending on some assumption made, which the engineering modelling developed later showed the necessity to be modified. In particular: i) the use of very diluted conditions, about 1:500 mainly to remove the heat of reaction with the flow of methanol itself; by using a different approach for heat removal and working under more optimized conditions the ratio can be decreased to a value estimated around 1:20, determining a complete change in costs; ii) the possible significant larger optimization in performances, by using a hollow-fiber type of reaction and optimized membrane configuration, as well as operative conditions, leading to an improvement by a factor about 20 in the productivities. Therefore, present assessment cannot be considered definitive, but as a case limit. It is possible a significant decrease in the costs and reactor sizes, but further experimentation is necessary.
Understanding the mechanism, particularly what are the active sites on the carbon catalyst surface and what is the nature of the transient intermediates
The activities are to: (i) Develop concepts for the mechanism of COCl2 formation over the carbon catalyst surface; (ii) verify the proposed mechanistic concepts by molecular modeling applying DFT analysis, (iii) study experimentally the carbon-chlorine interaction; (iv) study CO interaction with the active sites and activated carbon – chlorine complex; (v) study experimentally COCl2 synthesis in small scale batch reactors. The scope of these activities was to elucidate the mechanism of phosgene formation over carbon catalyst, which goes along with the identification of the catalytically active sites. This knowledge will support other tasks dealing with catalyst deactivation, the development of stable catalysts and the identification of process conditions inhibiting deactivation. A concept for Cl2 activation over carbon surfaces was developed and supported with corresponding DFT calculations. Experimental evidence for the postulated mechanism and catalytically active sites were also provided. Between the aspects investigated:
i) *C…Cl2 interactions was investigated experimentally, using various advanced spectroscopic techniques and a pulse setup, to gain experimental evidence for the proposed mechanism / active sites and to get insight into elementary processes occurring during interaction of Cl2 with C.
ii) In situ temperature-dependent ESR measurements of Cl2…C interaction using model carbon materials were performed, to evidence the nature of transiently formed chlorine intermediates.
iii) The interaction of CO with Cl2…C complexes was investigated, to understand the reactivity of various activated chlorine molecules towards CO.
iv) Synthesis and thorough characterization of new model carbon materials for phosgene synthesis was made to identify potential active sites on carbon material surface to enable a better understanding on the contribution of various sites on the Cl2 activation and COCl2 synthesis.
v) The influence of various process parameters and material pre-treatments on the formation of chlorinated side products during phosgene synthesis was analyzed.
v) Synthesis and mechanistic investigations on N-doped carbon materials were performed.
Understand the mechanism of deactivation, especially what triggers deactivation of carbon catalysts and identification of the measures to avoid deactivation / regeneration, identification of stable catalysts and of alternative, non carbon catalysts
Thorough characterize state of the art carbon catalysts (unused / fresh) for phosgene synthesis; (ii) derive structure-activity relationships by comparison of analytical data obtained from unused and used carbon catalysts; (iii) synthesize model carbon materials with an emphasis on given structural / chemical features to prove mechanistic assumptions, (iv) experimentally investigate factors influencing carbon catalyst deactivation. The scope is to investigate and understand the deactivation of carbon catalyst during phosgene synthesis.
Between some of the activities for this scope:
i) DFT analysis on the thermodynamics of Cl2 interaction with highly pre-chlorinated fullerene model carbon surfaces, to investigate if energetics of chlorination depend on degree of pre-chlorination of the model
ii) Investigations on catalyst regeneration. Carbon catalyst regeneration by treatment with CO, N2 and H2 was investigated at different temperatures
iii) Testing of further carbon materials in phosgene synthesis. Relevant carbon materials were investigated for their stability during COCl2 synthesis at different temperatures
iv) Comparison of catalytic properties of powder-type carbon materials and carbon extrudates, to get closer to the real catalyst material in phosgene plants
v) Testing of Al2O3 as a potential non-carbon catalyst for phosgene synthesis, to identify a non carbon catalyst with potentially higher stability regarding deactivation
As result of these activities, Stable catalysts for COCl2 synthesis were identified, based on the following studies: (i) process conditions for reduced / inhibited deactivation of carbon catalysts; (ii) properties of tailored carbon materials that are active and stable catalysts for COCl2 synthesis; iii) alternative non-carbon catalysts that can be used within membrane concept for DPC synthesis.
The results suggested that N-doping of the carbon structure increases the stability of the catalysts during COCl2 synthesis. However, at the same time catalyst activity is significantly reduced. A different mechanism for Cl2 activation observed for pure and N-doped carbon materials may serve as an explanation for their different deactivation properties.
Activated carbon materials with strongly improved stability when compared with state of the art activated carbon catalysts were identified in the course of catalyst screening experiments at lab-scale. The identification of carbon catalysts within improved stability is a major advance not only in terms of a better understanding of the factors responsible for carbon catalyst deactivation in the future but also regarding possible implementation of the identified materials in current COCl2 generators.
Alternative to carbon based catalysts, various metal based catalysts were selected and tested for catalytic Cl2 activation for phosgene productions. In-situ MS measurements conducted during chlorine adsorption in the presence of 5 wt. % CO containing He atmosphere at 150 °C have shown that among others, some type of alternative materials are a potential non-carbon catalyst for the COCl2 synthesis.
Design and performing a lab-scale demonstrator, identification of the concept for scaled reactor and application of insight gained for current COCl2 manufacture.
The activities are to (i) study the performances of lab-scale catalyst/membrane and nanoreactor developed in other WPs, (ii) analyze the effect of the reaction conditions and operative parameters (flux through the membrane, liquid flow, design of nanoreactor, etc.), (iii) compare the behavior (kinetics, stability) with that using conventional reactor/catalysts, and (iv) optimize the performances. The scope is to test lab-scale nanoreactor prototypes both in phosgene synthesis and coupled phosgene and DPC synthesis.
Between the activities for this objective:
i) membrane tester, with safety check and heater
ii) integrated fixed bed reactor, with design and assembly, cold commissioning
iii) integrated membrane tester, with tubular carbon membranes, membrane holder for integrated reactor, permeability tests and catalytic activity.
Various approaches for lab scale testing and demonstration were followed. Goal was to realize and test an integrated reactor combining in situ COCl2 synthesis and phosgenation of phenol to DPC. Regarding COCl2 synthesis two approaches were followed: COCl2 generation in a membrane or in a fixed bed reactor. A membrane tester was designed to test carbon membrane stemming from partners, a separate inlet is intended to provide the possibility to feed phenol into the reactor.
An integrated reactor for DPC synthesis at elevated temperatures and pressures via in situ generated COCl2 was designed and assembled. Both, the utilization of carbon membranes and a fix bed for COCl2 generation were possible with the setup. Graphite cylinders were used as a (potential) membrane. The alternative reactor approach, based on an integrated carbon catalyst cartridge for phosgene generation, was driven up to a successful proof of principle, i.e. reproducible and selective DPC formation via in situ generated COCl2. Technical challenges encountered during experimentation were caused by geometrical limitations in the setup used (responsible for low gas flows), PhOH penetration into the carbon cartridge (deactivating the carbon catalyst) and adsorption of significant fractions of the Cl2 introduced during a typical experimental time on the activated carbon (reducing DPC yield).
In terms of integrated reactor for in situ COCl2 synthesis and immediate conversion (to DPC), different options were analyzed to identify the preferable configuration. Patents for novel recator configuration were filed.
Basic techno-economic assessment of integrated reactor concept
The production of DPC in a reactor fed with carbon monoxide and chlorine besides phenol was demonstrated. In order to assess the impact of the new reaction and reactor concept it is important to investigate the impact of reaction conditions on all process steps required to build a complete DPC process plant. One important aspect would be the cost for phenol separation from the product. Selectivity is another important issue. The reactor modelling was performed for a 20kt DPC system. The proof of concept was demonstrated successfully. Safety assessments took place required to run the lab system.
Phosgene-free DPC synthesis
The activities are to: (i) design efficient water and methanol removal units to minimize the thermodynamic limitation in the DMC and DPC synthesis; (ii) develop stable and selective catalysts for the DMC and DPC synthesis; (iii) study the complex reaction network and establish structure-activity correlations; (iv) study experimentally the influence of critical process parameters.
Between the spects investigated:
1. Synthesis and characterization of various supported MoO3 and TiO2 mixed-oxide catalysts, to find an adequate selective catalyst for the DPC production from DMC and phenol, and to identify main reaction pathways on which DPC is formed.
2. Detailed kinetic and mechanistic studies, to understand complex reaction network
It should be finally mentioned that all expected Deliverables were produced in time.
Potential Impact:
Overview
The expected final project impacts are to develop:
1. new approaches in process intensification through a novel concept of multiphase nanoreactor design,
2. new approaches in multifunctional catalyst design by integrating catalyst and membrane functionalities in an approach aimed at process intensification,
3. new approaches for intrinsically safer design for reactions involving risky reagents.
The expected final result of the project is to verify to applicability and scalability of new concepts in catalysis related to the development of novel nanoreactors and related catalysts for the two listed target reactions and how they can improve (in these industrially-relevant multistage reactions) process intensification, sustainability (in terms of resource and energy efficiency) and safety of operations. Functional to this general objective are the development of catalytic nanomembranes, and of the associated novel reactor concepts. Due to challenging objective of developing novel nanoreactor concepts, the demonstration activities in the project are limited to the proof-of-the-concepts.
In line 2 the expected impacts are achieved, with a new type for scaled reactor for intrinsically safer design, new more active and stable catalysts developed, relevant knowledge/catalysts for alternative processes. Further research, however, is needed to exploit these results.
In line 1 the integration between the two stages, even if many different configurations have been explored, has been not proven successfully. However, project results in this line showed new concept of ceramic hollow fiber reactor which are relevant and innovative for a new process of direct H2O2 synthesis, solving potentially issues of current approaches – autoclave, fixed bed, microreactors – that have inhibited commercial direct H2O2 synthesis. In the integrated process approach, progresses and new advances have been made in membrane reactor modelling, in preparing multicomponent membranes and in understanding role of gradients on performances.
These results indicate the need to extend current examinations and consider further alternatives in process design, in particular regarding alternative heat removal solutions, membrane optimization from modeling, alternative reactors as hollow fiber, etc. Some of the results development within the project may also be exploited outside the project specific field. In addition, the research was proven quite successful in having a decisive impact to SMEs involved in the project to overcome general crisis and open new markets. Therefore, research in this line has generated new knowledge and concepts which translate (later) to innovation.
In terms of dissemination, the following activities have been presented and uploaded on the web site and on the Participant Portal:
- 28 posters
- 16 oral communications
- 18 publications and about other 10 in preparation
3 patents have been prepared. All these 3 patents have not been published yet and for this reason they could not be uploaded on the Participant Portal
Analysis of the impact
In terms of impact, different results have been obtained in lines 1 and 2, as indicated above. In line 1, there is still the need to further develop the materials and process. Actual techno-economic assessment was based on assumptions that need to be revised. Nevertheless, interesting materials in particular and nanoreactor configurations have been developed, which may be later exploited. In particular:
- novel concept of ceramic hollow fiber reactor which are relevant and innovative for a new process of direct H2O2 synthesis, solving potentially issues of current approaches – autoclave, fixed bed, microreactors – that have inhibited commercial direct H2O2 synthesis
- progresses and new advances have been made in membrane reactor modelling, in preparing multicomponent membranes and in understanding role of gradients on performances.
- novel multilayer-type tubular membranes
- novel flat-type AAO nanomembranes functionalized with nanoparticles, which may be utilized also for other type of applications such as in water purification and desalination
- novel type of anodising aluminum foams as scaled flat-type catalyst/membrane systems having higher mechanical robustness.
The list of results with exploitable foreground reports for line 1 seven results going from design of advanced reactor prototype to deposition method of nanoparticles within structured materials (foams, membranes) and new POSS catalysts. The possibility of PO production using the tubular membrane reactor is also under discussion, including regarding patentability. A patent has been issue by one of the partners (a SME) on the synthesis of POSS catalysts.
In line 2, both new catalysts, carbon membranes and new process configurations with membrane reactor have been successfully developed. The list of results with exploitable foreground reports for line 2 thirteen entries, going from new carbon-type and non-carbon-type catalysts to the novel reactor configuration (covered by two patents) and process.
The polycarbonate production capacity worldwide in 2012 was estimated to be about 4.7 million tons. The vast majority (about 80%) of capacity installed is phosgene based. Only a smaller portion (ca. 11%) of the phosgene based polycarbonate processes uses DPC as intermediate. In 2012 capacity installed exceeded demand. While demand for polycarbonate is growing worldwide several companies have announced projects for installation of additional capacity. At the current technical status of the project it is too early to be able to assess the likelihood of implementation of this particular reactor concept/system in future polycarbonate production plants. More detailed investigations of all aspects of DPC production are necessary, i.e. downstream processes. The potential will then depend on the general growth rate of the polycarbonate market and the economics of the competing processes at the locations of the future. Other important aspects are which of the companies operating worldwide will have access to the technology and at what cost/license fee.
Within the scope of the project, the production of DPC in a reactor fed with carbon monoxide and chlorine besides phenol was impressively demonstrated. However, an economic assessment of this new process step requires information beyond the results obtained so far. In particular, in order to assess the impact of the new reaction and reactor concept it is important to investigate the impact of reaction conditions on all process steps required to build a complete DPC process plant. One important aspect would be the cost for phenol separation from the product. Therefore a separation column should be installed. Its size is a direct result of phenol excess. Low phenol excess requires low energy for a later phenol separation step. The higher the phenol excess, the larger equipment size is required not only for the reactor but also for the following work-up.
Selectivity is another important issue. Could phosgene formation in the reactor lead to a different number or type of impurities? The first results of INCAS demonstrator are very promising, since minimal amount of byproducts have been observed.For an initial estimate of the economic potential the following cases could be compared regarding the invest cost:
A: Invest cost for a “stand alone” phosgene production unit plus a reactor of the size and running conditions with 4 fold phenol excess and
B: Invest cost for the newly developed reactor design with installed interior, in particular the required number of tubular membranes
The apparent delta to be considered regarding the reactor includes:
The number of required tubular membranes multiplied by the cost of each tube and the lifetime factor of the catalyst. While there is information available on the cost of graphite tubes, the additional cost for their installation in the reactor is still to be determined. The tube lifetime is assumed to be as long as that of the typical phosgene catalyst due to the same material and operating conditions. The exchange of a membrane tube is an issue since it requires the shutdown of the whole DPC plant and should be taken into account.
Considering invest cost estimates published by SRI consulting in their PEP yearbook 2010 for phosgene production units suggests that combining in situ phosgene generation and reaction with phenol appears economically favorable from an invest cost point of view. However, further detailed analysis of a complete DPC production process including e.g. separation of excess phenol, analysis/separation of side products is required to provide a meaningful economic assessment.
Regarding engineering (basic flowsheet, operation conditions, targets for scaling-up, safety, energy and material balance, process integration), available documentation was included in the technical part. The reactor modelling was performed for a 20kt DPC system. Experiments were conducted at lab scale size. Safety assessments took place required to run the lab system. The proof of concept was demonstrated successfully.
Regarding opportunities. About 16% of the worldwide phosgene consumption in 2013 (CEH report phosgene 2013) was used in polycarbonate production plants around the world. While the proof of principle and reactor design for in situ phosgenation was demonstrated and described for the reaction step in the production of DPC, the key principle and reactor could potentially be successful for other phosgene using production porcesses, too.
Currently, the new INCAS concept is being proposed and assessed as an alternative to the existing phase separation process used for DPC synthesis. The in-situ phosgene generation allowing for sparing the reactor block(s) for phosgene synthesis seems attractive at first view. Opportunities among other companies are also investigated for pursuing an INCAS device where in-situ phosgene is available to activate any secondary reaction.
3 patents have been prepared, of which:
1) Application reference: DExxxxxxx (translation from German: ≈ Process for phosgenation of hydroxy, thiol, amino and/or formamid functional groups containing compounds)
2) Application reference:DExxxxxxx (translation from German: ≈ Process for phosgenation of hydroxy, thiol, amino and/or formamid functional groups containing compounds)
3) Application reference: EP 13190500.2 Synthesis and use of polyhedral oligomeric
silsesquioxane catalyst compositions
All these 3 patents have not been published yet; the URL is not available and for this reason they could not be uploaded on the Participant Portal
4 publications have been submitted but not yet accepted and published, and 2 are still in preparation. For this reason they could not be uploaded on the Participant Portal. Here is the list.
The 4 submitted are:
1) “Adsorbate-induced restructuring of metal NPs”
Payam Kaghazchi, Timo Jacob, Cristina Popa, Tianwei Zhu, Emiel J. M. Hensen - Faraday Discussions
2) “ Structure of Palladium Nanoparticles under Oxidative Conditions”
Cristina Popa, Tianwei Zhu, Ionut Tranca, Payam Kaghazchi, Timo Jacob, Emiel J. M. Hensen – submitted to PCCP
3) “Direct synthesis of propene oxide from propene, hydrogen and oxygen in a catalytic membrane reactor”
Emila Kertalli, Dulce M. Perez Ferrandez, Jaap C. Schouten, T. Alexander Nijhuis
4) “Bent carbon surface moieties as activate sites on carbon catalysts for phosgene synthesis: a model study using C60”, A. Pashigreva, N. Gupta, W. Song, C. Diedrich, E. Hensen, L. Mleczko, E. Ember, S. Roggan, J. Lercher. Angewandte Chemie International Edition - Wiley-VCH.
The 2 in preparation are:
1)“Propylene oxide synthesis in acidic conditions”
Emila Kertalli, Lucas. S. van Rijnsoever, Violeta Paunovic, Jaap C. Schouten, T. Alexander Nijhuis
2) “Experimental and computational investigation of H2O2 decomposition pathway on Pd, PdO catalysts in the presence of H2 and C3H6”
Tao Chen, Emilia Kertalli, Kevin Calloway, Jaap Cornelius Schouten, Tjeerd Alexander Nijhuis, Simon Podkolzin
7 publications are in preparation in collaboration between TUM and BAYER.For this reason they could not be uploaded on the Participant Portal.Here is the list:
1) “Reversible chlorine activation processes on model carbon materials”, A. Pashigreva, N. Gupta, B. Felkel, W. Song, C. Diedrich, K. Metaxas, E. Hensen, L. Mleczko, E. Ember, S. Roggan, J. Lercher. Chemical Communications - Royal Society of Chemistry
2) “Nitrogen and oxygen modified carbon nano-materials as stable non-metal catalysts for transient phosgene synthesis”, N. Gupta, E. Ember, J. Lercher, S. Roggan, L. Mleczko. Angewandte Chemie - Wiley-VCH.
3) “Effect of thermal and O2 treatment on the carbon catalysts performance”, N. Gupta, E. Ember, J. Lercher, S. Roggan, L. Mleczko. Applied catalysis A: General – Elsevier.
4) “ɣ-Al2O3 catalyzed Cl2 activation and COCl2 synthesis”, N. Gupta, E. Ember, J. Lercher, S. Roggan, L. Mleczko. ChemCatChem - Wiley-VCH
5) “Comparative study of Al2O3- and MgO- modified ZrO2 catalysts on dimethyl carbonate formation from methanol and CO2”, B. Peng, E. Ember, J. Lercher, S. Roggan, K. Metaxas, L. Mleczko. Green Chemistry - Royal Society of Chemistry.
6) “Development of stable and efficient catalysts for the DPC synthesis”, B. Peng, E. Ember, J. Lercher, S. Roggan, L. Mleczko. Applied catalysis A: General – Elsevier.
7) “Synthesis, characterization and test of highly efficient zeolitic sorbents for the separation of binary H2O/MeOH and MeOH/PhOH mixtures”, B. Peng, E. Ember, J. Lercher, S. Roggan, L. Mleczko. Journal of Molecular Catalysis A: Chemical – Elsevier
2 more publications in preparation, (not uploaded on the participant portal) are:
1) “Preparation and permeation properties of novel α-alumina tubular composite membranes by consecutive deposition of palladium thin layers and TS-1 nanocrystals” A.Prieto M. Palomino, U. Díaz, A. Corma, S. Abate, S. Gentiluomo, S. Perathoner and G. Centi (ITQ-CSIC/INSTM)
2) “Bi-functional Pd/Au@TS-1 catalysts for direct propylene epoxidation production through in-situ generated H2O2 in supercritical conditions” A. Prieto, M. Palomino, U. Díaz, A. Corma (ITQ-CSIC)
Strategic impacts
The general objective to provide a strategic advantage and added value to society, in terms of competitiveness, reduction of environmental footprint and industrial safety may be difficult to be reached by developing an alternative safer reagent or feed-stock (the classical example of substituting phosgene), or a synthesis methodology (the other classical examples of using supercritical CO2 or ionic liquids instead of the common sol-vents). The quantitative potential impact of these approaches is limited and not in line with the expected impact, as well as limited their pushing role towards a major change in sustainability of the chemical production, e.g. they have a minor effect in providing a strategic advantage as requested in the initial call. The changes in macroeconomic scenario and in society demands require, on the other hand, to really progressing in the development of new enabling mechanisms towards sustainability. For a "strategic advantage" it is necessary to provide new mechanisms for designing the industrial chemical processes, for example which enable a parallelized multi-modular design.
Therefore, the project expected impacts can be summarized as follows:
- A new approach in process intensification through the novel concept of multiphase nanoreactor design; this novel design improves of one order of ma-nitude the process intensification with respect to actual microreactor and thus of about two-three order of magnitude with respect to conventional reactors.
This novel concept enables an improvement in resource efficiency (energy) of over 25-30% with contemporaneous lowering of the costs, and waste production, and improves safety of operations.
- A new approach for intrinsically safer design for reactions involving risky reagents, with a nanoreactor design with integrated transient generation of the reagent (phosgene, in our case). This design also allow to operate the phosgenation in gas phase, and thus solvent-free operations, with great benefits in terms of quality of the product (avoided chlorinated byproducts) and reduction of over 20% in energy costs.
The results of INCAS project showed that for line 2 these strategic impacts can be considered to be met, as indicated before, although further experimentation would be necessary to develop the developed technology to implementation. In line 1, some promising results have been obtained, but there is the need to further develop the concept.
It should be remarked that all the studied reactions are of great industrial relevance. The reaction of clean phosgenation (e.g. with transient generation of phosgene) for DPC synthesis is another illustrative example of the approach used in this project. As commented before, it is better to reduce the risk of using phosgene, instead of finding novel phosgene-free processes or phosgene-substitutes, to improve the sustainability in several industrial processes of synthesis of large-volume chemicals (DPC - diphenylcarbonate, isocyanate and polyurethanes), and fine and specialty chemicals production (active pharmaceutical in-gredients, Taxol, Prodrugs, Agrochemicals, etc.). After about 20 years of effort, the majority of production is still based on phosgene. It is thus preferable to invest on a new intrinsically-safe technology as that proposed in this project. The large involvement in this project (many person/months) of a company world leader in this sector testifies that they believe that the proposed novel technology could have a major impact in this area.
List of Websites:
www.incasproject.eu