Deactivation of Au/CeOx water gas shift catalysts

Abstract A series of CeO 2 -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 H 2 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 H 2 , 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/CeO 2 catalysts are discussed.

[1]  Hiroaki Sakurai,et al.  Synergism in the catalysis of supported gold , 1993 .

[2]  K. Domen,et al.  Carbon monoxide and carbon dioxide adsorption on cerium oxide studied by Fourier-transform infrared spectroscopy. Part 1.—Formation of carbonate species on dehydroxylated CeO2, at room temperature , 1989 .

[3]  Polycarpos Falaras,et al.  Low-temperature water-gas shift reaction over Au/CeO2 catalysts , 2002 .

[4]  D. Jiang,et al.  Stability and Deactivation of Au/Fe2O3 Catalysts for CO Oxidation at Ambient Temperature and Moisture , 2002 .

[5]  I. Mitov,et al.  Influence of the microscopic properties of the support on the catalytic activity of Au/ZnO, Au/ZrO2, Au/Fe2O3, Au/Fe2O3–ZnO, Au/Fe2O3–ZrO2 catalysts for the WGS reaction , 2000 .

[6]  Bernard Delmon,et al.  Low-Temperature Oxidation of CO over Gold Supported on TiO2, α-Fe2O3, and Co3O4 , 1993 .

[7]  M. Flytzani-Stephanopoulos,et al.  Active Nonmetallic Au and Pt Species on Ceria-Based Water-Gas Shift Catalysts , 2003, Science.

[8]  J. M. Zalc,et al.  Are Noble Metal-Based Water–Gas Shift Catalysts Practical for Automotive Fuel Processing? , 2002 .

[9]  K. Domen,et al.  Adsorption of carbon monoxide and carbon dioxide on cerium oxide studied by Fourier-transform infrared spectroscopy. Part 2.—Formation of formate species on partially reduced CeO2 at room temperature , 1989 .

[10]  M. Flytzani-Stephanopoulos,et al.  Nanostructured Au–CeO2 Catalysts for Low-Temperature Water–Gas Shift , 2001 .

[11]  Raymond J. Gorte,et al.  Studies of the water-gas-shift reaction on ceria-supported Pt, Pd, and Rh: Implications for oxygen-storage properties , 1998 .

[12]  Masatake Haruta,et al.  Size- and support-dependency in the catalysis of gold , 1997 .

[13]  Harold H. Kung,et al.  Nature of the active site for CO oxidation on highly active Au/γ-Al2O3 , 2002 .

[14]  V. Perrichon,et al.  Reduction of CeO2 by hydrogen. Magnetic susceptibility and Fourier-transform infrared, ultraviolet and X-ray photoelectron spectroscopy measurements , 1991 .

[15]  Dong Ju Moon,et al.  Molybdenum carbide catalysts for water–gas shift , 2000 .

[16]  Peter Claus,et al.  Identification of active sites in gold-catalyzed hydrogenation of acrolein. , 2003, Journal of the American Chemical Society.

[17]  Raymond J. Gorte,et al.  Deactivation Mechanisms for Pd/Ceria During the Water-Gas Shift Reaction , 2002 .

[18]  V. Idakiev,et al.  Low-temperature water-gas shift reaction over Au/α-Fe2O3 , 1996 .

[19]  J. Schwank.  Catalytic gold , 1983 .