Au/3DOM LaCoO3: High-performance catalysts for the oxidation of carbon monoxide and toluene

Abstract

Rhombohedrally crystallized three-dimensionally ordered macroporous (3DOM) LaCoO3 and its supported Au (xAu/3DOM LaCoO3, x=0–7.63wt%) catalysts were prepared using the polymethyl methacrylate-templating and polyvinyl alcohol-protected reduction methods, respectively. Physicochemical properties of the materials were characterized by means of numerous analytical techniques, and their catalytic activities were evaluated for the oxidation of toluene and CO. It is shown that the xAu/3DOM LaCoO3 samples displayed a 3DOM architecture and a high surface area of 24–29m2/g. The 7.63Au/3DOM LaCoO3 sample exhibited the highest adsorbed oxygen species concentration and the best low-temperature reducibility, and hence the best catalytic performance. Over 7.63Au/3DOM LaCoO3, the T10%, T50%, and T90% (corresponding to the temperatures required for achieving a reactant conversion of 10%, 50%, and 90%) were 136, 188, and 202°C for toluene oxidation at space velocity (SV)=20,000mL/(gh), and −61, −6, and 42°C for CO oxidation at SV=10,000mL/(gh), respectively. Over xAu/3DOM LaCoO3, the apparent activation energies were 31.4–37.4kJ/mol for toluene oxidation and 16.6–19.4kJ/mol for CO oxidation. We believe that the high oxygen adspecies concentration, good low-temperature reducibility, and strong interaction between Au and 3DOM LaCoO3 might account for the excellent catalytic performance of 7.63Au/3DOM LaCoO3.