Transient Isotopic Studies and Microkinetic Modeling of CO Methanation over Nickel Catalysts
D. Lorito, Pascal Fongarland, Yves Schuurman
Abstract
The methanation of CO over a 20 wt % Ni/Al2O3 catalyst was studied with different transient experiments. CO dissociation was found to be reversible and faster than the formation of methane. SSITKA experiments showed that two pools of surface intermediates lead to the formation of methane. The transient experiments could be adequately described by a microkinetic model based on two distinct adsorbed CO species. One CO species proceeds through direct dissociation, and the other, through hydrogen assisted dissociation to a common CH* intermediate that leads to methane. The model is consistent with literature DFT studies that show that the direct CO dissociation occurs over edge or step sites and hydrogen assisted dissociation occurs over terrace sites.