Activity of Au, Ni, and Au-Ni Catalysts in the Water-Gas Shift Reaction and Carbon Monoxide Oxidation

摘要

Au/Al_2O_3, NiO_x/Al_2O_3, and (Au + NiO_x)/Al_2O_3 composites have been prepared by ion exchange and impregnation. Their structural and electronic properties, including the size and shape of sup- ported metal particles and the oxidation state and ligand environment of the Au and Ni atoms, have been investigated. The catalytic action of Au/Al_2O_3, NiO_x/Al_2O_3, and (Au + NiO_x)/Al_2O_3 in the water-gas shift reaction and carbon monoxide oxidation is reported. At 300-450℃, the CO conversion over (Au + NiO_x)/Al_2O_3 exceeds the sum of the CO conversions over the monometallic catalysts Au/Al_2O_3 and NiO_x/Al_2O_3 by a factor of 2-3. An explanation is suggested for the nonadditive increase in the CO conversion over the Au-Ni catalysts.