Effects of oxide supports on the water-gas shift reaction over Pt-Ni bimetallic catalysts: Activity and methanation inhibition

The activity and product selectivity of the water-gas shift (WGS) reaction were compared for Pt-Ni bimetallic catalysts supported on gamma-Al2O3, SiO2, TiO2, CeO2 and ZrO2. The catalysts were synthesized by impregnation, and were characterized by pulse CO chemisorption, transmission electron microscopy (TEM), and extended X-ray absorption fine structure (EXAFS). The reactions were carried out in a batch reactor equipped with a Fourier transform infrared (FTIR) spectrometer. Catalysts on reducible or partially reducible supports (CeO2,TiO2 and high surface area ZrO2 (HSA-ZrO2)) show higher activity than those on non-reducible supports (gamma-Al2O3, SiO2 and low surface area ZrO2 (LSA-ZrO2)). Based on catalyst weight, the Pt Ni bimetallic catalysts follow the activity trend of CeO2>HSA-ZrO2> TiO2>SiO2> LSAZrO(2). Based on CO uptake values, the activity follows a similar trend except that Pt-Ni/TiO2 becomes as active as Pt Ni/CeO2 due to the lower CO uptake value of Pt-Ni/TiO2. At a similar CO conversion, the selectivity to CH4, the undesired product, is highest over Pt Ni/SiO2, followed by Pt Ni/CeO2 and Pt Niky-Al2O3, and very low on Pt Ni/TiO2 and Pt Ni/HSA-ZrO2. Overall, CeO2, TiO2 and HSA-ZrO2 are promising supports for the Pt Ni bimetallic WGS catalyst. (C) 2013 Elsevier B.V. All rights reserved,