Water-gas Shift Reaction over Ceria-promoted Pt catalysts

Introduction The fuel processor in which hydrocarbon fuels can be converted into hydrogen has recently attracted much attention as a result of the advancement in the fuel cell technology. In a fuel processor, the water-gas shift (WGS) reaction plays a crucial role in the transformation of CO, a well-known poisonous gas to electrode of fuel cell, into hydrogen through reaction with steam. In WGS reaction, conventional commercial Cu-based catalysts suffer from some drawbacks to be applied to a small-scale fuel processor with characteristics such as a cyclic operation and possibility for air contamination [1]. To overcome these weak points of commercial WGS catalysts, some noble metal catalysts including Au and Pt group metals have been extensively studied [2]. Although intensive works have been conducted to find out the WGS catalysts both active at low temperatures and stable during various operation modes, there is still need to develop the advanced WGS catalyst to be applied for practical application [3]. In this work, we have found that Pt-Ce/TiO2 prepared by a single-step co-impregnation method shows the highest WGS activity at low temperatures among ceria-promoted Pt catalysts supported on γ-Al2O3, SiO2, TiO2 (P-25), CeO2, SiO2-Al2O3, yttria-stabilized zirconia (YSZ) and ZrO2. Furthermore, the nice correlation can be made between the low-temperature water-gas shift activity and the amounts of chemisorbed CO as well as the reducibility of ceria near Pt at low temperatures.