Multiscale investigation of the mechanism and selectivity of CO2 hydrogenation over Rh(111)

Sun, Shijia, Higham, Michael D., Zhang, Xingfan and Catlow, C. Richard A. ORCID: https://orcid.org/0000-0002-1341-1541 2024. Multiscale investigation of the mechanism and selectivity of CO2 hydrogenation over Rh(111). ACS Catalysis 14 , 5503–5519. 10.1021/acscatal.3c05939

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Abstract

CO2 hydrogenation over Rh catalysts comprises multiple reaction pathways, presenting a wide range of possible intermediates and end products, with selectivity toward either CO or methane being of particular interest. We investigate in detail the reaction mechanism of CO2 hydrogenation to the single-carbon (C1) products on the Rh(111) facet by performing periodic density functional theory (DFT) calculations and kinetic Monte Carlo (kMC) simulations, which account for the adsorbate interactions through a cluster expansion approach. We observe that Rh readily facilitates the dissociation of hydrogen, thus contributing to the subsequent hydrogenation processes. The reverse water–gas shift (RWGS) reaction occurs via three different reaction pathways, with CO hydrogenation to the COH intermediate being a key step for CO2 methanation. The effects of temperature, pressure, and the composition ratio of the gas reactant feed are considered. Temperature plays a pivotal role in determining the surface coverage and adsorbate composition, with competitive adsorption between CO and H species influencing the product distribution. The observed adlayer configurations indicate that the adsorbed CO species are separated by adsorbed H atoms, with a high ratio of H to CO coverage on the Rh(111) surface being essential to promote CO2 methanation.

Item Type:	Article
Date Type:	Published Online
Status:	Published
Schools:	Chemistry Cardiff Catalysis Institute (CCI)
Publisher:	American Chemical Society
ISSN:	2155-5435
Funders:	EPSRC
Date of First Compliant Deposit:	8 April 2024
Date of Acceptance:	13 March 2024
Last Modified:	15 Apr 2024 11:45
URI:	https://orca.cardiff.ac.uk/id/eprint/167821

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