Effect of Au promoter in CuO/CeO2 catalysts for the oxygen-assisted WGS reaction

The present work focuses on the development of bimetallic Au–Cu catalyst supported on CeO2 for the oxygen-assisted water-gas-shift (OWGS) reaction. Au–CuO/CeO2 catalyst with Au loadings of 0.5, 1 and 1.5 wt.% and Cu loadings of 7, 11 and 20 wt.% were prepared by incipient wetness impregnation. The as-prepared catalysts were characterized by means of XRD, BET, and a set of temperature programmed methods. The catalysts activity was evaluated in CO-PROX, WGS and OWGS reactions. For WGS reaction the gold addition did not improve the activity of the better 7% CuO/CeO2 catalyst. Addition of 1% of gold to CuO/CeO2 improved the catalyst activity in CO-PROX and widened the operation window. Either with λ = 1 and 2, complete CO conversion is achieved at low temperature, usually below 120 °C, with high selectivities with all gold-containing catalysts. When small oxygen amount is added to the WGS mixture, the activities of all the catalysts tested were improved in terms of CO conversion, particularly catalysts containing both Au and CuO, although parallel hydrogen oxidation also is slightly improved. Catalyst with 1% Au and 7% CuO supported on ceria achieves almost equilibrium CO conversion at 220 °C when O2/CO = 0.5 is added to the feedstream.