PMMA-templating generation and high catalytic performance of chain-like ordered macroporous LaMnO3 supported gold nanocatalysts for the oxidation of carbon monoxide and toluene

Rhombohedrally crystallized chain-like LaMnO3 and its supported gold (xAu/LaMnO3; x = 1.4, 3.1, and 4.9 wt%) catalysts have been prepared using the poly(ethylene glycol)-assisted polymethyl methacrylate-templating and gas bubble-assisted polyvinyl alcohol-protected reduction methods, respectively. It is shown that there were good correlations of surface adsorbed oxygen species concentration and low-temperature reducibility with catalytic activity of the samples for the oxidation of CO and toluene. Among the LaMnO3 and xAu/LaMnO3 samples, 4.9Au/LaMnO3 performed the best, giving the T-50% and T-90% of 61 and 91 degrees C for CO oxidation, and of 201 and 226 degrees C for toluene combustion, respectively. The apparent activation energies (29-50 and 47-62 kJ/mol) of the chain-like LaMnO3 and xAu/LaMnO3 samples were much smaller than those (63 and 97 kJ/mol) of the bulk LaMnO3 sample for the oxidation of CO and toluene, respectively. We believe that the higher surface area and oxygen adspecies concentration and better low-temperature reducibility as well as the strong interaction between Au nanoparticles and chain-like LaMnO3 support might account for the high catalytic performance of 4.9Au/LaMnO3. (C) 2013 Elsevier B.V. All rights reserved.