Catalytic performance enhancement by alloying Pd with Pt on ordered mesoporous manganese oxide for methane combustion

Ordered mesoporous Mn2O3 (meso-Mn2O3) and meso-Mn2O3-supported Pd, Pt, and Pd-Pt alloy x(PdyPt)/meso-Mn2O3; x = (0.10-1.50) wt%; Pd/Pt molar ratio (y) = 4.9-5.1 nanocatalysts were prepared using KIT-6-templated and poly(vinyl alcohol)-protected reduction methods, respectively. The meso-Mn2O3 had a high surface area, i.e., 106 m(2)/g, and a cubic crystal structure. Noble-metal nanoparticles (NPs) of size 2.1-2.8 nm were uniformly dispersed on the meso-Mn2O3 surfaces. Alloying Pd with Pt enhanced the catalytic activity in methane combustion; 1.41(Pd5.1Pt)/meso-Mn2O3 gave the best performance; T-10%,T- T-50%,T- and T-90% (the temperatures required for achieving methane conversions of 10%, 50%, and 90%) were 265, 345, and 425 degrees C, respectively, at a space velocity of 20000 mL/(g.h). The effects of SO2, CO2, H2O, and NO on methane combustion over 1.41(Pd5.1Pt)/meso-Mn2O3 were also examined. We conclude that the good catalytic performance of 1.41(Pd5.1Pt)/meso-Mn2O3 is associated with its high-quality porous structure, high adsorbed oxygen species concentration, good low-temperature reducibility, and strong interactions between Pd-Pt alloy NPs and the meso-Mn2O3 support. (C) 2016, Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.