Deactivation of Au/CeOx water gas shift catalysts

A series of CeO2-supported gold catalysts were prepared and demonstrated to possess very high activities for the water gas shift reaction-a critical step in the production of H2 for use in petroleum refining, chemicals synthesis, and proton exchange membrane fuel cells. While some of these catalysts were more active than a commercial Cu-based catalyst, they were susceptible to deactivation. Characterization using techniques including X-ray photoelectron and infrared spectroscopies indicated that the deactivation was caused primarily by blockage of the active sites by carbonates and/or formates. These species appeared to be formed by CO and H2, and their formation was facilitated by oxygen deficient sites on ceria. The catalytic activity was fully recovered by calcination of the deactivated materials in flowing air at elevated temperatures. Details concerning the deactivation-regeneration behavior and microstructure of the Au/CeO2 catalysts are discussed.