Periodic Reporting for period 1 - EMPaTHY (use of multiscale modElling to Minimize coke ProducTion during the methanol-to- HYdrocarbon process)
Reporting period: 2019-11-01 to 2021-10-31
Two important scientific problems have been addressed in this MSCA project. The first problem concerns understanding the mechanism of coke formation in the methanol to hydrocarbon (MTH) reaction. The MTH reaction is an important industrial reaction that is catalyzed by zeolites and zeo-type materials. In this study, the widely used H-ZSM-5 zeolite catalyst has been considered. A drawback of the MTH reaction is a relatively quick catalyst deactivation caused by coke formation during operation. Modifying the catalytic system such that it becomes more resistant to coking will enable the MTH reaction to be more widely used in the industry.
The second problem concerns the application of the multiscale methodology to the MTH reaction. The coke formation is a result of processes happening at various length- and time scales. Being able to apply the multiscale methodology to the MTH reaction is then a crucial step towards understanding the mechanism of coke formation. The two scientific problems of this MSCA project are therefore closely interconnected.
Conclusions of the project:
At the time of submission of this report, we have been able to apply the multiscale methodology to the methanol to dimethyl ether reaction. The methanol to dimethyl ether reaction is a small part of the extensive reaction network of the MTH reaction. The preliminary results shows that the mass fraction of methanol is gradually decreasing from the inlet to the outlet of the reactor, the methanol conversion is 13%. Furthermore, the methanol mass fraction within the catalyst pellets is very low. This indicates that the process is mass transfer limited.
The second problem concerns the application of the multiscale methodology to the MTH reaction. The coke formation is a result of processes happening at various length- and time scales. Being able to apply the multiscale methodology to the MTH reaction is then a crucial step towards understanding the mechanism of coke formation. The two scientific problems of this MSCA project are therefore closely interconnected.
Conclusions of the project:
At the time of submission of this report, we have been able to apply the multiscale methodology to the methanol to dimethyl ether reaction. The methanol to dimethyl ether reaction is a small part of the extensive reaction network of the MTH reaction. The preliminary results shows that the mass fraction of methanol is gradually decreasing from the inlet to the outlet of the reactor, the methanol conversion is 13%. Furthermore, the methanol mass fraction within the catalyst pellets is very low. This indicates that the process is mass transfer limited.
The work in this MSCA project was organized into six work packages. Work package 1 (WP1) involved constructing a microkinetic model by use of density functional theory (DFT) calculations. WP2 involved computing the micropore diffusivity of the species involved in the MTH reaction. The micropore diffusivity was obtained from molecular dynamics (MD) simulations. Originally, WP3 involved computing the mesopore diffusivity from kinetic Monte Carlo (kMC) simulations. As described in the report, we found out that it did not serve the overall objectives of the project to carry out work in this work package.
WP4 concerned the computation of the macropore diffusivity and obtaining the effective diffusivity of the species involved in the MTH reaction.
WP5 involved carrying out multiscale simulations of the MTH reaction taking place in a fixed bed capillary reactor.
WP6 consists of using the multiscale model to understand the cause of coke formation and suggest modifications of the catalytic system such that the coke formation could be minimized. At the time of writing, WP6 is work in progress.
The main results of the project are the following:
• We have been able to demonstrate the use of the multiscale methodology on the methanol to dimethyl ether reaction. The reaction network of the methanol to dimethyl ether reaction is a subset of the reaction network of the MTH reaction
• We were able to show that the methanol to dimethyl ether reaction is mass transfer limited.
The results of WP2, the computation of micropore diffusivity from MD simulations, were communicated in for of an oral presentation at the online conference ACS Spring 2021. An overview of the preliminary results of the project was presented as a poster presentation at the online conference International Conference on Theoretical Aspects of Catalysis 2021.
WP4 concerned the computation of the macropore diffusivity and obtaining the effective diffusivity of the species involved in the MTH reaction.
WP5 involved carrying out multiscale simulations of the MTH reaction taking place in a fixed bed capillary reactor.
WP6 consists of using the multiscale model to understand the cause of coke formation and suggest modifications of the catalytic system such that the coke formation could be minimized. At the time of writing, WP6 is work in progress.
The main results of the project are the following:
• We have been able to demonstrate the use of the multiscale methodology on the methanol to dimethyl ether reaction. The reaction network of the methanol to dimethyl ether reaction is a subset of the reaction network of the MTH reaction
• We were able to show that the methanol to dimethyl ether reaction is mass transfer limited.
The results of WP2, the computation of micropore diffusivity from MD simulations, were communicated in for of an oral presentation at the online conference ACS Spring 2021. An overview of the preliminary results of the project was presented as a poster presentation at the online conference International Conference on Theoretical Aspects of Catalysis 2021.
In this project we have been able to apply the multiscale methodology to the methanol to dimethyl ether reaction. The extension to the MTH reaction is straight-forward. The application of the multiscale methodology to a reaction of industrial interest opens up the possibility for closer cross-disciplinary collaborations. By having the multiscale methodology available, researchers from various backgrounds can more easily collaborate. An example is that researchers with background in density functional theory (DFT) calculations can collaborate with researchers with background in molecular dynamics (MD) simulations and computational fluid dynamics (CFD) simulations.
The possibility of a closer collaboration will lead to more complex problems in catalysis being solved in a shorter time. This will eventually lead to a faster progress of the society, for instance towards the adaptation of more sustainable processes.
The possibility of a closer collaboration will lead to more complex problems in catalysis being solved in a shorter time. This will eventually lead to a faster progress of the society, for instance towards the adaptation of more sustainable processes.