(740e) Strong Shape/Crystal Plane Effect of Nanoscale Ceria on the Activity of CeO2-Based Catalysts for the Water-Gas Shift Reaction

Doping of gold or platinum into cerium oxide (ceria) has been reported to greatly promote the catalytic activity of ceria for the low-temperature water-gas-shift (WGS) reaction.^1-4 However, how to maximize this promotion by optimizing the design and synthesis of catalysts is still under investigation. In this paper, we focus on the shape/crystal plane effect of ceria on the catalytic activity for the WGS reaction. We have recently reported a strong structural effect on gold/ceria catalysts, where gold on nanoceria with different crystal shapes was prepared by a two-step process, consisting of a first step of hydrothermal synthesis of ceria nanorods, nanocubes, or nanopolyhedra, and a second step of introducing gold via deposition-precipitation (DP).⁵ The activity of the three catalysts for the WGS reaction was ranked as: rod > polyhedron >> cube. The {110} surfaces of the ceria nanorods kept the gold dispersed and showed maximum activity . We have since confirmed this effect in the Cu-CeO2 system, where copper on ceria nanorods shows much higher activity for the WGS reaction than that on nanocubes. Results from the catalytic activity evaluation, HREM, XPS and H2-TPR analyses of these materials will be presented and discussed.

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