Study of the water-gas shift reaction over Pt supported on CeO2–ZrO2 mixed oxides

Abstract

The water gas shift (WGS) reaction was studied on Pt/CeO2, Pt/ZrO2 and Pt/CexZrx-1O2 catalysts. All the samples were characterized by a variety of physical and spectroscopic techniques. The catalysts activities were evaluated at 250°C in a recirculating reactor through CO conversion versus time test and also by in situ diffuse reflection infrared Furier transform spectroscopy (DRIFT). The samples activity for the WGS reaction depended on chemical composition. Pt/CexZrx-1O2 catalysts with x≥0.5 were more active than Pt/CeO2, probably because the addiction of Zr to ceria increased both the surface area and the reducibility of ceria. The lowest CO conversion rates were obtained on Pt/ZrO2 and Zr-rich Pt/CexZrx-1O2 samples. Based on DRIFT experiments, this result was interpreted by considering that in the WGS formate associative mechanism the stability of formats species is higher on Zr-rich supports.