Monte Carlo study of CO hydrogenation on cobalt model catalysts

Abstract

Useful information on catalytic reactions can be achieved using Monte Carlo simulations combined with experimental data from model catalysts. We present a comprehensive analysis of the simulation studies of CO hydrogenation on a hexagonal surface using a discrete computer model for the irreversible reaction kinetics with no interactions between the surface species but their mutual reactions. The simulation results are compared to experimental data from a cobalt foil model catalyst at 101 kPa and 525 K. As a result, the following microscopic picture of the reaction on the catalyst surface is extracted: the rate-limiting reaction step is the termination of the carbon chains (α-hydrogenation), hydrogen atoms occupy different adsorption sites from other reactants, and the diffusion of hydrogen along the surface is fast. The model is also used to address the relevance of the ensemble effects for CO dissociation and the surface sensitivity of the CO hydrogenation reaction. Our simulation results imply that these aspects have little effect on the rates of hydrocarbon formation.