Yadavalli, Sai Sharath;
Jones, Glenn;
Benson, Raz L;
Stamatakis, Michail;
(2023)
Assessing the Impact of Adlayer Description Fidelity on Theoretical Predictions of Coking on Ni(111) at Steam Reforming Conditions.
The Journal of Physical Chemistry C
10.1021/acs.jpcc.3c02323.
(In press).
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Abstract
Methane steam reforming is an important industrial process for hydrogen production, employing Ni as a low-cost, highly active catalyst, which, however, suffers from coking due to methane cracking. Coking is the accumulation of a stable poison over time, occurring at high temperatures; thus, to a first approximation, it can be treated as a thermodynamic problem. In this work, we developed an Ab initio kinetic Monte Carlo (KMC) model for methane cracking on Ni(111) at steam reforming conditions. The model captures C−H activation kinetics in detail, while graphene sheet formation is described at the level of thermodynamics, to obtain insights into the “terminal (poisoned) state” of graphene/coke within reasonable computational times. We used cluster expansions (CEs) of progressively higher fidelity to systematically assess the influence of effective cluster interactions between adsorbed or covalently bonded C and CH species on the “terminal state” morphology. Moreover, we compared the predictions of KMC models incorporating these CEs into mean-field microkinetic models in a consistent manner. The models show that the “terminal state” changes significantly with the level of fidelity of the CEs. Furthermore, high-fidelity simulations predict C−CH island/rings that are largely disconnected at low temperatures but completely encapsulate the Ni(111) surface at high temperatures.
Type: | Article |
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Title: | Assessing the Impact of Adlayer Description Fidelity on Theoretical Predictions of Coking on Ni(111) at Steam Reforming Conditions |
Open access status: | An open access version is available from UCL Discovery |
DOI: | 10.1021/acs.jpcc.3c02323 |
Publisher version: | https://doi.org/10.1021/acs.jpcc.3c02323 |
Language: | English |
Additional information: | © 2023 The Authors. Published by American Chemical Society. This is an open access article under the CC BY 4.0 license Attribution 4.0 International (https://creativecommons.org/licenses/by/4.0/) |
UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science > Dept of Chemical Engineering |
URI: | https://discovery.ucl.ac.uk/id/eprint/10169130 |
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