The mechanism of the water-gas shift reaction (WGS, CO + H2O → H2 + CO2) has been investigated on powder and model CuO-CeO2 catalysts using a combination of in-situ techniques {X-ray diffraction (XRD), pair-distribution-function analysis (PDF), X-ray absorption spectroscopy (XAS), environmental scanning tunneling microscopy (ESTM), infrared spectroscopy (IR), ambient-pressure X-ray photoelectron spectroscopy (AP-XPS)}. Under reaction conditions, the CuO-CeO2 catalysts undergo chemical transformations that drastically modify their composition with respect to that obtained during the synthesis process. The active phase in the catalysts combines Cu and partially reduced ceria. The oxide support is not a simple spectator during reaction, facilitating the dissociation of water and in some cases modifying the chemical properties of the supported metal. Data of AP-XPS and IR spectroscopy indicate that formate species are not necessarily involved in the main reaction path for the water-gas shift. Thus, a pure redox mechanism or associative mechanisms that involve either carbonate-like (CO3, HCO3) or carboxyl (HOCO) species should be considered. The results of density-functional calculations point to a HOCO species, formed at the copper-ceria interface, as the key intermediate for the WGS.

In situ studies and the mechanism of the water-gas shift reaction on Cu-ceria catalysts

251st National Meeting (2016)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.