Three-dimensionally ordered macroporous CoCr2O4-supported Au-Pd alloy nanoparticles: Highly active catalysts for methane combustion

Three-dimensionally ordered macroporous CoCr2O4 (3DOM CoCr2O4) and its supported Au-Pd alloy (xAuPd(y)/3DOM CoCr2O4; x = 0.98 and 1.93 wt%; Pd/Au molar ratio (y) = 1.93-1.96) nanocatalysts were prepared using the polymethyl methacrylate-templating and polyvinyl alcohol-protected reduction methods, respectively. Physicochemical properties of the samples were characterized by means of a number of techniques, and their catalytic activities were evaluated for methane combustion. The 3DOM CoCr2O4 and xAuPdy/3DOM CoCr2O4 samples possessed a high-quality 3DOM structure and a surface area of 33-36 m(2)/g. The Au-Pd alloy nanoparticles (NPs) with an average size of 3.3 nm were uniformly dispersed on the surface of the samples. The 1.93AuPd(1.95)/3DOM CoCr2O4 sample showed the best catalytic performance: the T-10%, T-50%, and T-90% (temperatures required for achieving methane conversion of 10, 50, and 90%, respectively) were 305, 353, and 394 degrees C at a space velocity (SV) of 20,000 mL/(gh). The effects of SV, water vapor, and sulfur dioxide on the catalytic activity of the 1.93AuPd(1.95)/3DOM CoCr2O4 sample were also examined. It is concluded that the excellent catalytic performance of 1.93AuPd(1.95)/3DOM CoCr2O4 was associated with the higher surface area and adsorbed oxygen species concentration, better low-temperature reducibility, and strong interaction between Au-Pd alloy NPs and 3DOM CoCr2O4. (C) 2016 Elsevier B.V. All rights reserved.