Abstract
A heterogeneous catalytic microkinetic model is developed and implemented in a zero4 dimensional plasma model for the dynamic study of methane non-oxidative coupling over Ni(111) at residence times and power densities consistent with experimental reactors.
The microkinetic model is thermodynamically consistent and is parameterised based on the heats of chemisorption of surface species on Ni(111). The surface network explicitly accounts for the interactions of plasma species, namely molecules, radicals and vibrationally excited states with the catalyst active sites via adsorption and Eley-Rideal reactions. The Fridman-Macheret model is used to describe the enhancement of the rate of the dissociative adsorption of vibrationally excited CH4, H2 and C2H6. In combination with a previously developed detailed kinetic scheme for non-thermal methane plasma, 0D simulation results bring insights on the complex dynamic interactions between
the plasma phase and the catalyst during methane non-oxidative coupling. Differential turnover frequencies achieved by plasma-catalysis are higher than those of equivalent plasma-only and catalysis-only simulations combined, however this performance can only be sustained momentarily. Hydrogen produced from dehydrogenation of ethane via electron collisions within the plasma is found to quickly saturate the surface and even promote the conversion of surface CH3∗ back to methane.
The microkinetic model is thermodynamically consistent and is parameterised based on the heats of chemisorption of surface species on Ni(111). The surface network explicitly accounts for the interactions of plasma species, namely molecules, radicals and vibrationally excited states with the catalyst active sites via adsorption and Eley-Rideal reactions. The Fridman-Macheret model is used to describe the enhancement of the rate of the dissociative adsorption of vibrationally excited CH4, H2 and C2H6. In combination with a previously developed detailed kinetic scheme for non-thermal methane plasma, 0D simulation results bring insights on the complex dynamic interactions between
the plasma phase and the catalyst during methane non-oxidative coupling. Differential turnover frequencies achieved by plasma-catalysis are higher than those of equivalent plasma-only and catalysis-only simulations combined, however this performance can only be sustained momentarily. Hydrogen produced from dehydrogenation of ethane via electron collisions within the plasma is found to quickly saturate the surface and even promote the conversion of surface CH3∗ back to methane.
| Original language | English |
|---|---|
| Pages (from-to) | 19987–20003 |
| Number of pages | 17 |
| Journal | The Journal of Physical Chemistry C |
| Volume | 126 |
| Issue number | 47 |
| Early online date | 17 Nov 2022 |
| DOIs | |
| Publication status | Published - 1 Dec 2022 |
Bibliographical note
AcknowledgementWe acknowledge and greatly appreciate the assistance from Dr. Mihailova from Plasma Matters B.V. in working with the software Plasimo and from Dr Marcus Campbell Bannerman from the University of Aberdeen for providing access to the computational cluster used for carrying out the simulations in this work.
The work was supported by the UK Engineering and Physical Sciences Research Council (EPSRC) New Investigator Award, grant no. EP/R031800/1. For the purpose of open access, the author has applied a Creative Commons Attribution (CC BY) licence to any Author Accepted Manuscript version arising.