Enhanced catalytic performance for methane combustion of 3DOM CoFe2O4 by co-loading MnOx and Pd–Pt alloy nanoparticles

Abstract

Three-dimensionally ordered macroporous (3DOM) CoFe2O4, zMnOx/3DOM CoFe2O4 (z=4.99–12.30wt%), and yPd–Pt/6.70wt% MnOx/3DOM CoFe2O4 (y=0.44–1.81wt%; Pd/Pt molar ratio=2.1–2.2) have been prepared using the polymethyl methacrylate microspheres-templating, incipient wetness impregnation, and bubble-assisted polyvinyl alcohol-protected reduction strategies, respectively. All of the samples were characterized by means of various techniques. Catalytic performance of the samples was measured for methane combustion. It is shown that the as-prepared samples exhibited a high-quality 3DOM structure (103±20nm in pore size) and a surface area of 19–28m2/g, and the noble metal or alloy nanoparticles (NPs) with a size of 2.2–3.0nm were uniformly dispersed on the macropore wall surface of 3DOM CoFe2O4. The loading of MnOx on CoFe2O4 gave rise to a slight increase in activity, however, the dispersion of Pd–Pt NPs on 6.70MnOx/3DOM CoFe2O4 significantly enhanced the catalytic performance, with the 1.81Pd2.1Pt/6.70MnOx/3DOM CoFe2O4 sample showing the highest activity (T10%=255°C, T50%=301°C, and T90%=372°C at a space velocity of 20,000mL/(gh)). We believe that the excellent catalytic activity of 1.81Pd2.1Pt/6.70MnOx/3DOM CoFe2O4 was related to its well-dispersed Pd–Pt alloy NPs, high adsorbed oxygen species concentration, good low-temperature reducibility, and strong interaction between MnOx or Pd–Pt NPs and 3DOM CoFe2O4.