Sun Shijia, Higham Michael D, Zhang Xingfan, Catlow C Richard A
Kathleen Lonsdale Materials Chemistry, Department of Chemistry, University College London, London WC1H 0AJ, United Kingdom.
Research Complex at Harwell, Rutherford Appleton Laboratory, Harwell, Oxon OX11 0FA, United Kingdom.
ACS Catal. 2024 Mar 28;14(8):5503-5519. doi: 10.1021/acscatal.3c05939. eCollection 2024 Apr 19.
CO 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 CO 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 CO 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 CO methanation.
在铑催化剂上进行的CO加氢反应包含多种反应途径，会产生多种可能的中间体和终产物，其中对CO或甲烷的选择性尤为引人关注。我们通过进行周期性密度泛函理论（DFT）计算和动力学蒙特卡罗（kMC）模拟，详细研究了在Rh(111)晶面上CO加氢生成单碳（C1）产物的反应机理，该模拟通过团簇展开方法考虑了吸附质之间的相互作用。我们观察到铑很容易促进氢的解离，从而推动后续的加氢过程。逆水煤气变换（RWGS）反应通过三种不同的反应途径发生，CO加氢生成COH中间体是CO甲烷化的关键步骤。我们考虑了温度、压力和气体反应物进料组成比的影响。温度在决定表面覆盖率和吸附质组成方面起着关键作用，CO和H物种之间的竞争吸附影响产物分布。观察到的吸附层构型表明，吸附的CO物种被吸附的H原子隔开，Rh(111)表面上H与CO覆盖率的高比例对于促进CO甲烷化至关重要。
