A comparative study of the water gas shift reaction over platinum catalysts supported on CeO2, TiO2 and Ce-modified TiO2

WGS reaction has been investigated on catalysts based on platinum supported over CeO2, TiO2 and Ce-modified TiO2. XPS and XANES analyses performed on calcined catalysts revealed a close contact between Pt precursors and cerium species on CeO2 and Ce-modified TiO2 supports. TPR results corroborate the intimate contact between Pt and cerium entities in the Pt/Ce-TiO2 catalyst that facilitates the reducibility of the support at low temperatures while the Ce-O-Ti surface interactions established in the Ce-modified TiO2 support decreases the reduction of TiO2 at high temperature. The changes in the support reducibility leads to significant differences in the WGS activity of the studied catalysts. Pt supported on Ce-modified TiO2 Support exhibits better activity than those corresponding to individual CeO2 and TiO2-supported catalysts. Additionally, the Ce-TiO2-supported catalyst displays better stability at reaction temperatures higher than 573 K that observed on pure TiO2-supported counterpart. Activity measurements, when coupled with the physicochemical characterization of catalysts suggest that the modifications in the surface reducibility of the support play an essential role in the enhancement of activity and stability observed when Pt is supported on the Ce-modified TiO2 substrate. (C) 2009 Elsevier B.V. All rights reserved.