Effect of transition metal doping on the catalytic performance of Au-Pd/3DOM Mn2O3 for the oxidation of methane and o-xylene

Palladium-based catalysts are highly active for eliminating volatile organic compounds. Reducing the use of noble metals and enhancing performance of a catalyst are always desirable. The three-dimensionally ordered macroporous (3DOM) Mn2O3-supported transition metal M (M=Mn, Cr, Fe, and Co)-doped Au-Pd nanoparticles (NPs) with an Au-Pd-xM loading of 1.86-1.97 wt% were prepared using the modified polyvinyl alcohol-protected reduction method. It is found that the Au-Pd-xM NPs with a size of 3.6-4.4nm were highly dispersed on the surface of 3DOM Mn2O3. The 1.94wt% Au-Pd-0.21Co/3DOM Mn2O3 and 1.94wt% Au-Pd-0.22Fe/3DOM Mn2O3 samples performed the best for the oxidation of methane and o-xylene, respectively. The methane oxidation rate at 340 degrees C (339.0 x 10(-6) mol/(g(pd) s)) over 1.94wt% Au-Pd-0.21Co/3DOM Mn2O3 was three times higher than that (93.8 x 10-6 mol/(gpd s)) over 1.97 wt% Au-Pd/3DOM Mn2O3, and the o-xylene reaction rate at 140 degrees C (2.59 mu mol/(g(N) s) over 1.94wt% Au-Pd-0.22Fe/3DOM Mn2O3 was two times higher than that (0.93 mu mol/(g(N) s) over 1.97 wt% Au-Pd/3DOM Mn2O3. It is concluded that doping a certain amount of the transition metal to Au-Pd/3 DOM Mn2O3 could modify the microstructure of the alloy NPs, thus improving the oxygen activation and methane adsorption ability. We are sure that the M-doped Au-Pd/3DOM Mn2O3 materials are promising catalysts for the efficient removal of volatile organic compounds. (C) 2017 Elsevier B.V. All rights reserved.