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Development of a bifunctional hierarchically structured zeolite based nano-catalyst using 3D-technology for direct conversion of methane into aromatic hydrocarbons via methane dehydroaromatization

Periodic Reporting for period 1 - ZEOCAT-3D (Development of a bifunctional hierarchically structured zeolite based nano-catalyst using 3D-technology for direct conversion of methane into aromatic hydrocarbons via methane dehydroaromatization)

Reporting period: 2019-04-01 to 2020-09-30

The ZEOCAT-3D project proposes an alternative to the current production methods of aromatics, which consists of obtaining these high-value chemicals (benzene, naphthalene, among others) from methane from sources like biogas and natural gas through an improved catalytic process called methane dehydroaromatization (MDA).
The main drawbacks of this process are low methane conversion, low selectivity to the desired compounds, and the quicky catalyst deactivation due to carbon deposition in the catalyst pores. Nevertheless, the ZEOCAT-3D project regards developing and producing a new catalyst capable of improving these issues (objective 1).
The methodology of the project will go from laboratory to pilot-scale demonstration in a real environment. Multiscale modeling of the process will be developed to optimize catalyst design and operation conditions for different methane feedstock at the lab-scale (objective 2). After that, the process will be upscaled and validated, and the construction of a final prototype will be carried out (objective 3).
ZEOCAT-3D regards developing an industrial process capable of obtaining high-value chemicals while reducing the dependence on the current fossil fuel. Therefore, the optimization of these catalytic processes will bring enormous advantages for increasing the exploitation of natural gas and biogas.
The results achieved so far for each objective of the project are described below:

1. Development and production of improved catalyst
The activities towards developing the MoXOY augmented-mixed phase (ZSM-5 and SAPO-34) zeolite crystal of hierarchical structure were initially focused on the synthesis of hierarchical structure and the core-shell structures of individual zeolite components, namely SAPO-34 and ZSM-5. Optimisation of the synthesis conditions was also carried out and revealed the beneficial role of the functionalization of SAPO-34.
On the other hand, the FSP (Flame Spray Pyrolysis) technology is used to incorporate Mo and Mo-based active species into the zeolite and to synthesize doped catalysts. The adjustment of the precursor mixture and the operating parameters is vital to achieving suitable properties of the nanopowder obtain. Thus, the liquid precursor mixture formulations have been optimised, and its stability was tested to ensure the reproducibility of the synthetic process during the whole batch. Simultaneously, several adjustments related to the operating conditions must be adapted for each batch produced.
Adjustments both in precursor mixture formulation and in the operating parameters resulted in particle size reduction of at least 50% and enabled the preparation of an FSP protocol. Nevertheless, optimisations of the process are still ongoing by producing additional batches to obtain a larger amount of samples for further characterisations, including other dopants like Ni and Pt. Still, the results achieving until this moment are satisfactory.
Regarding the optimization of elements and conditions of 3D-printing, first tests using DLP (Digital Light Processing) using commercial ceramic loaded resin and the calcined ZSM-5 reference powder have been developed to study the mechanical properties of the structure.

2. Rational design of catalyst/multiscale modeling
Modeling activities include the development of hierarchical models and simulations to three levels:
- Modeling catalytic material. The active site of the catalyst and the determination of the reaction path for the ethylene formation have been developed, concluding that the catalyst used to activate methane is almost optimal.
- Modeling and simulation of the process via MDO – A first approach of the reactor and the upstream models has been carried out. The different units involved in the process have been identified, allowing them to develop a first global mass balance that will be the base of the MDO.
- Modeling of the reactor using CFD – A full-size reactor has been modeled using a combined 3D-1D model based on representative volume elements (RVEs), which have been modeled using CFD simulations of a reacting flow through a porous medium, employing the numerical solver OpenFOAM® reactingFoam.

3. Design, construction and validation of catalytic reactor
The task related to developing a prototype to treat approximately 5m3/h of gas flow inlet to obtain 1kg/h of products has just started. Thus, only the research of the state of the art of the operating conditions has been carried out, which will be the base of the reactor design.
By contrast, the development of the membranes required in the separation processes is more advanced. Different types of commercial membranes and amines have been studied for upgrading biogas from methane (purifying gas fed), concluding that using X50 PP membrane and DEA as solvent >95% of CO2 can be removed, and >98% of CH4 can be recovered. On the other hand, the specifications established in the Grant Agreement in the separation of the MDA effluent (H2 permeance>10-7 mol.m-2.s-1.Pa-1 H2/C6H6 >200) have also been achieved by using H2 selective membrane. The catalytic reactor will be placed between these two membrane processes.
ZEOCAT-3D will contribute to the expected impact as detailed in the DoA (Section 2.1 Annex 1, Part B). The ZEOCAT-3D partners will focus their activities on improving the MDA process, producing high-value chemicals from natural gas or biogas. Thus, they actively contribute to the following impacts mentioned in the work programme, providing the EU significant advantages.
- Reducing the global dependence on the current fossil fuels resources such as coal, tar, and petroleum since the raw material used in the aromatic production will be natural and biogas. Thus, the dependence of the EU on fossil fuel importations will decrease, and the use of fossil fuels will be reduced by more than 30%, compared to the current production.
- Improving the main drawbacks of the current MDA process, which is based on hard operating conditions at high pressures and temperatures for the correct development of the reactions involved. Thus, the new innovative process that will be developed during the project will improve the industrial competitiveness and operating costs.
- These hard-operating conditions promote the use of expensive reactors and large CO2 emissions. By contrast, ZEOCAT-3D will enable a decrease in greenhouse gas emissions and a CAPEX reduction higher than 20% thanks to the compact catalytic reactor used, which will be developed.
- Upscaling the correlations developed, showing the flexibility of the process, studying the feedstock variability and the potential scalability of the catalyst and the catalytic processes without compromising the catalytic activity.
- Improving deactivation problems caused by coke deposition in other industrial processes such as fluid catalytic cracking (FCC), methanol to olefins (MTO), and methanol to gasoline (MTG), among others.