Periodic Reporting for period 1 - BIOP (Upcycling plastic wastes: biopolymers for a circular economy)
Periodo di rendicontazione: 2021-09-01 al 2023-08-31
BIOP addresses one of the most critical environmental issues derived from human activities, plastic wastes. The project focuses mostly on poliolefins recycling into lighter value-added molecules that can be used as building blocks to synthetize new biobased polymeric units, in combination with specific biomass-derived platform chemicals such as 2,5-furandicarboxylic acid (FDCA). The work aims to provide solutions to climate change and the environment by reducing the massive amount of single-use plastic wastes, reducing the production of plastics from fossil fuels (thus reducing carbon dioxide emissions and fossil fuels dependency) and providing new approaches to obtain bio-based plastics. The latter clearly benefits the whole society in the current scenario of climate change and is essential to pave the way towards a circular economy.
The overall objectives of the project are: (i) design and development of efficient catalysts for the conversion of hydrocarbons (polyolefins) to alkanes and light alkenes, (ii) design and development of efficient catalysts for the conversion of light alkenes (ideally from the step (i)) to glycols and (iii) one-pot production of glycols and FDCA, the last one obtained via 5-hydroxymethylfurfural (HMF, biomass-derived molecule) oxidation.
The project results have led to the following overall conclusions: (i) the development of iridium based organometallic catalysts immobilized over different inorganic supports and its combination with rhenium-based catalysts lead to efficient systems to degrade hydrocarbons to the desired alkanes and light alkenes, being the support key to modulate the product distribution. Investigating the exact role of each support and how to enhance and/or modulate its participation in the catalytic reaction will definitively pave the way to the design of efficient heterogeneous catalysts for plastic upcycling. (ii) the design of gold-based catalysts supported over titanium containing zeolites lead to potential systems for the production of glycols in liquid media and (iii) the application of those systems in the one-pot production of glycols and FDCA comprises a potential and completely new approach to produce biobased plastics
The overall objectives of the project are: (i) design and development of efficient catalysts for the conversion of hydrocarbons (polyolefins) to alkanes and light alkenes, (ii) design and development of efficient catalysts for the conversion of light alkenes (ideally from the step (i)) to glycols and (iii) one-pot production of glycols and FDCA, the last one obtained via 5-hydroxymethylfurfural (HMF, biomass-derived molecule) oxidation.
The project results have led to the following overall conclusions: (i) the development of iridium based organometallic catalysts immobilized over different inorganic supports and its combination with rhenium-based catalysts lead to efficient systems to degrade hydrocarbons to the desired alkanes and light alkenes, being the support key to modulate the product distribution. Investigating the exact role of each support and how to enhance and/or modulate its participation in the catalytic reaction will definitively pave the way to the design of efficient heterogeneous catalysts for plastic upcycling. (ii) the design of gold-based catalysts supported over titanium containing zeolites lead to potential systems for the production of glycols in liquid media and (iii) the application of those systems in the one-pot production of glycols and FDCA comprises a potential and completely new approach to produce biobased plastics
During the development of the first scientific part, catalytic alkane metathesis (CAM) has been evaluated as a suitable approach to upcycle hydrocarbons (polyolefins) at moderate temperatures. This process entails the use of a tandem catalyst which usually consists of a combination of two independent functions: one active in the alkane dehydrogenation reaction and other in the alkene metathesis process, which is usually based on Re2O7. In this context, a pincer-ligated iridium complex (dehydrogenation catalyst) has been combined with a rhenium-based (metathesis) catalyst, being the effect of immobilizing the Ir complex over different supports deeply investigated during the project. α-Al2O3 and SiO2 have been used as supports to immobilize the Ir complex along with TiO2 and three zeolites: mordenite and two ZSM-5 samples with different SiO2/Al2O3 molar ratio, respectively. FTIR spectroscopy has been used to confirm the complex grafting and to elucidate the anchoring site to the support. Additionally, the supports have been dehydroxylated at different conditions to evaluate its possible impact in both the complex grafting and the catalytic activity. All the catalysts have been evaluated in the cross-alkane metathesis of n-dodecane and n-octane, molecules acting as models of heavy (polyethylene) and light alkanes, respectively. To the best of our knowledge, this is the first time that both support nature effect and support dehydroxylation effect are systematically evaluated in the degradation of heavy alkanes through CAM with light alkanes over supported pincer-ligated iridium complexes. The optimized systems lead to a range of alkanes but also to light alkenes, one of the main objectives of the project. Moreover, it has been demonstrated that the product distribution depends not only on the support type but also on support dehydroxylation which open a new research line towards catalyst optimization for plastic upcycling.
On the other hand, the conversion of light alkenes to glycols involves two cascade reactions, the alkene epoxidation and the epoxide ring opening to form glycols. The work done within this part has involved the optimization of catalysts based on gold nanoparticles supported over titanium containing zeolites. Different synthetic methods have been explored along with different zeolite compositions, and methods for gold impregnation. The optimization of gold deposition has constituted an important scientific achievement. Preliminary results regarding light alkenes epoxidation have been very promising, leading to potential systems for the production of glycols in liquid media.
The last scientific part involved the optimization of catalysts and reaction conditions for the joint (ep)oxidation of light alkenes and HMF. Although the synthetized catalysts for alkenes epoxidation are potentially active in the HMF oxidation reaction over the same reaction conditions, this step was not investigated due to the premature end of the project. However, it will be part of future work.
The results have been disseminated in several ways although, unfortunately, all programed activities were not able to be undertaken due to the project end. The project results have been exposed during group meeting presentations and were sent in abstract format to the 15th European Congress on Catalysis (EuropaCat2023) and to the Spanish Conference on Catalysis (Secat2023) to be considered as part of the conferences program. Unfortunately, and due to the abrupt end of the project, the fellow was not able to participate in any of the conferences, programmed in June and August 2023. The project has been disseminated in a press release (https://sevilla.abc.es/sevilla/sevi-investigacion-sevillana-apuesta-reciclar-202102200753_noticia.html).
On the other hand, the conversion of light alkenes to glycols involves two cascade reactions, the alkene epoxidation and the epoxide ring opening to form glycols. The work done within this part has involved the optimization of catalysts based on gold nanoparticles supported over titanium containing zeolites. Different synthetic methods have been explored along with different zeolite compositions, and methods for gold impregnation. The optimization of gold deposition has constituted an important scientific achievement. Preliminary results regarding light alkenes epoxidation have been very promising, leading to potential systems for the production of glycols in liquid media.
The last scientific part involved the optimization of catalysts and reaction conditions for the joint (ep)oxidation of light alkenes and HMF. Although the synthetized catalysts for alkenes epoxidation are potentially active in the HMF oxidation reaction over the same reaction conditions, this step was not investigated due to the premature end of the project. However, it will be part of future work.
The results have been disseminated in several ways although, unfortunately, all programed activities were not able to be undertaken due to the project end. The project results have been exposed during group meeting presentations and were sent in abstract format to the 15th European Congress on Catalysis (EuropaCat2023) and to the Spanish Conference on Catalysis (Secat2023) to be considered as part of the conferences program. Unfortunately, and due to the abrupt end of the project, the fellow was not able to participate in any of the conferences, programmed in June and August 2023. The project has been disseminated in a press release (https://sevilla.abc.es/sevilla/sevi-investigacion-sevillana-apuesta-reciclar-202102200753_noticia.html).
The progresses beyond the state of the art can be separated in three points:
(i) Attending to the first scientific part, the immobilization of the synthetized Ir complex over different supports has led to a group of catalysts that not only degrade efficiently hydrocarbons but also lead to different products distributions. This is a progress beyond the state of the art: the possibility of enhancing and/or modulating the product range by choosing the appropriate support or by modifying properly the support. As stated, this opens a new research line: investigating the exact role of each support and how to enhance and/or modulate its participation in the catalytic reaction will be a significant step towards the design of efficient heterogeneous catalysts for plastic upcycling.
(ii) Respect to the second scientific part, the optimization of gold deposition has constituted an important scientific achievement since most of the used methods entailed a big gold loss which is logically not desirable from the economical viewpoint. Preliminary results regarding light alkenes epoxidation have been very promising.
(iiI) The combination of biomass and plastic valorization is a completely new approach that goes beyond the state of the art. The development of technologies that add value simultaneously to plastics and biomass wastes will transform Europe in a pioneer region in this field, providing solutions to global worldwide issues.
(i) Attending to the first scientific part, the immobilization of the synthetized Ir complex over different supports has led to a group of catalysts that not only degrade efficiently hydrocarbons but also lead to different products distributions. This is a progress beyond the state of the art: the possibility of enhancing and/or modulating the product range by choosing the appropriate support or by modifying properly the support. As stated, this opens a new research line: investigating the exact role of each support and how to enhance and/or modulate its participation in the catalytic reaction will be a significant step towards the design of efficient heterogeneous catalysts for plastic upcycling.
(ii) Respect to the second scientific part, the optimization of gold deposition has constituted an important scientific achievement since most of the used methods entailed a big gold loss which is logically not desirable from the economical viewpoint. Preliminary results regarding light alkenes epoxidation have been very promising.
(iiI) The combination of biomass and plastic valorization is a completely new approach that goes beyond the state of the art. The development of technologies that add value simultaneously to plastics and biomass wastes will transform Europe in a pioneer region in this field, providing solutions to global worldwide issues.