(722c) Flame Spray Pyrolysis Synthesized Cu-CeO2 Catalysts for Low Temperature WGS Reaction

Recently, the water-gas shift (WGS) reaction has attracted renewed attention because of production of high purity H₂ in conjunction with fuel cell power generation. Cu is the active metal for the low temperature WGS reaction. The main problem with the current catalyst formulations is that they are sensitive to even small amounts of sulfur. So far several wet synthesis methods has been reported for the preparation of Cu based catalysts for the low temperature WGS reaction. Recently, the synthesis of catalysts using flame spray pyrolysis method become attractive since it is a rather inexpensive route for large-scale production of thermally stable, high-surface area nano-materials. The FSP technique converts precursor droplets into solid nano-particles in flames and has been widely employed for the large-scale production of carbon black, while vapor-fed flames have been used for synthesis of several catalysts. In this way, high-purity materials with novel meta-stable phases are made that are not accessible by conventional wet chemical and solid-state processes.  Particularly, FSP allows for the controlled synthesis of nano-particles with high specific surface area (SSA), which resulted from the small size of nano-particles, and well-defined chemical composition, as recently demonstrated on both a laboratory and pilot scale. The present study mainly aimed at synthesis of sulfur tolerant Cu-CeO₂ catalysts for the low temperature WGS reaction using Flame Spray pyrolysis synthesis method. Various ratios Cu-CeO₂ solid solutions have been synthesized to find out the optimum ratio between Cu and CeO₂. These catalysts were characterized using XRD, TPR, BET, N₂O chemisorption, TEM and XPS techniques. The catalysts were evaluated for low temperature WGS reaction in the presence and absence of H₂S. The TPR analysis showed the presence of Cu promoted the reduction of CeO₂ to much lower temperatures indicating strong interaction between Cu and Ce. Catalytic activity measurements suggest that our FSP synthesized catalyst exhibits better activity than co-precipitated synthesized catalyst. These interesting findings will be discussed in the presentation.