(120b) Improving Carbon-Tolerance of Ni Reforming Catalysts and Electro-Catalysts by Surface Alloying and the Impact of Alloying On the Surface Chemistry

Metallic Ni is used as a catalyst in hydrocarbons reforming reactions to form synthetic gas and as the anode electro-catalyst to electrochemically oxidize fuels over Solid Oxide Fuel Cells (SOFC). The processes are run at temperatures from ~750 to 1200 K. A critical problem with the Ni catalysts in the above-mentioned applications is the formation of carbon deposits on the catalyst surface, which evolve into carbon filaments, ultimately diminishing the performance of the catalyst. We have shown that the tolerance of Ni catalysts and electro-catalysts to carbon-induced deactivation in hydrocarbon steam reforming, partial oxidation, and electro-chemical oxidation reactions can be significantly improved by impregnating Ni with small amounts of Sn. We have utilized density functional theory (DFT) calculations along with a number of experimental studies, including atomistic characterization of catalysts and kinetic reactor studies, to identify the mechanism by which Sn influences the chemical transformations taking place on Ni catalysts. In this context, we will discuss the Sn-induced changes in the nature of the catalytically active sites and the mechanisms responsible for the improved carbon tolerance of Sn/Ni as compared to monometallic Ni.