A comparative study of water gas shift reaction over gold and platinum supported on ZrO2 and CeO2-ZrO2

In this study platinum- and gold-based catalysts supported on ZrO2 and ceria-zirconia solid solution have been characterized by several techniques (TPR, XRD, BET, HRTEM) and tested in the water gas shift (WGS) reaction under feed conditions typical of an autothermal reformer outlet. Platinum and gold catalysts behave differently especially in the range of 423-513 K, with gold being superior than platinum. The possibility of modifying the redox and structural characteristics of zirconia with the insertion of ceria allowed us to conclude that the bulk redox proper-ties of the support play a secondary role, while the key parameter for an active WGS catalyst is the nature of metal support interface. This, in turn, depends on the metal particle distribution and on the structural and morphological properties of support. It has been found that the synergism between precious metals and support can be designed with an appropriate choice of the parameters of synthesis and the characteristics of support. (C) 2008 Elsevier B.V. All rights reserved.