Study of the oxidation by water of Au/CeGaOx catalysts active in the WGS reaction

J. VECCHIETTI, S. COLLINS, A. BONIVARDI; L. BARRIO, D. STACCHIOLA; S. BERNAL

Upton

Congreso; 4th International Congress on Operando Spectroscopy; 2012

Brookhaven National Laboratory

We have investigated the synthesis and catalytic activity of catalysts supported on CeGaOx mixed oxides, which show an improved reducibility as compared with pure ceria. Gold supported catalysts on both CeO2 and CeGaOx show activity towards the water gas shift (WGS) reaction [1,2]. It has been suggested in the literature that the WGS reaction on gold based catalysts proceeds via a redox mechanism. CO initially adsorbs on the metal sites and from there reduces the oxide support. The support is then re-oxidized by water [3], being this the rate limiting step. Thus, we studied the reoxidation by water of the Au/CeO2 and Au/CeGaOx catalysts (Ce/Ga = 75/25, 80/20, and 95/5 mol/mol, coded Ce75Ga25, Ce80Ga20 and Ce95Ga05, respectively) by time-resolved X-ray diffraction (XRD) and infrared spectroscopy (DRIFT) coupled with Mass Spectrometry (MS). The results obtained by combining XRD, DRIFT and MS techniques suggest that the support re-oxidation by water may not be the rate limiting step for the WGS reaction on cerium-based gold-supported catalysts.