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

- Au-Pd-xM (M = Mn, Cr, Fe, Co) particles are fabricated and well dispersed on the 3DOM Mn2O3 surface.
- Au-Pd-0.21Co/3DOM Mn2O3 exhibits the best catalytic activity for CH4 oxidation.
- Au-Pd-0.22Fe/3DOM Mn2O3 shows the best catalytic activity for o-xylene oxidation.
- M doping can enhance the oxygen activation and methane adsorption ability.

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 3.6-4.4 nm were highly dispersed on the surface of 3DOM Mn2O3. The 1.94 wt% Au-Pd-0.21Co/3DOM Mn2O3 and 1.94 wt% 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 °C (339.0 × 10−6 mol/(gPd s)) over 1.94 wt% Au-Pd-0.21Co/3DOM Mn2O3 was three times higher than that (93.8 × 10−6 mol/(gPd s)) over 1.97 wt% Au-Pd/3DOM Mn2O3, and the o-xylene reaction rate at 140 °C (2.59 μmol/(gN s) over 1.94 wt% Au-Pd-0.22Fe/3DOM Mn2O3 was two times higher than that (0.93 μmol/(gN s) over 1.97 wt% Au-Pd/3DOM Mn2O3. It is concluded that doping a certain amount of the transition metal to Au-Pd/3DOM 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.

The transition metal M (M = Mn, Cr, Fe, and Co)-doped Au-Pd/3DOM Mn2O3 nanocatalysts show super catalytic performance for methane and o-xylene oxidation, which is attributed to the enhanced oxygen activation and methane adsorption ability.298