Selective Catalytic Oxidation of CO for Fuel Cell Application

Over 50 catalysts wee evaluated for selective oxidation of CO in a H₂-rich gas from room temperature to 250°C. These included Au-, Pt-, Cu-, Pd-based and some other transitional metal containing catalysts prepared by conventional impregnation or co-precipitation methods. Based on the amount of catalyst used, the AU, Pt, and Cu containing catalysts exhibited high activities and selectivities toward CO oxidation. Some catalysts like hopcalite, Pt-Ru/hopcalite, Co/Al₂O₃, Ru/Al₂O₃, Pd/CeO₂-TiO₂, Pn/SnO₂, and Ag/Co₃O₄ showed little activity. α-Fe₂O₃ supported Au catalysts were more active than TiO₂, ZnO, Al₂O₃, and Y-zeolite supported Au. For Au/α-FeO₂O₃, the catalyst activity increased with increasing Au loading while the CO oxidation selectivity only slightly changed. Another group of catalysts was studied extensively (promoted Pt/Al₂O₃ and Pt/SiO₂ catalysts). Cobalt oxide modified Pt/Al₂O₃ showed 100% CO conversion below 100°C. The CuO-CeO₂ catalyst was very promising for selective CO oxidation, showing 100% CO conversion at about 150°C, which was very close to that of the commercial Pt/Al₂O₃ catalyst.