Au/MnOx/3DOM La0.6Sr0.4MnO3: Highly Active Nanocatalysts for the Complete Oxidation of Toluene
2015
Jiang, Yang | Deng, Jiguang | Xie, Shaohua | Yang, Huanggen | Dai, Hongxing
Three-dimensionally ordered macroporous La₀.₆Sr₀.₄MnO₃ (3DOM LSMO) supported manganese oxide and gold (yAu/zMnOₓ/3DOM LSMO; y = 1.76–6.85 wt %; z = 8 wt % (weight percent of Mn₂O₃)) nanocatalysts were fabricated by means of in situ poly(methyl methacrylate)-templating and gas bubble-assisted poly(vinyl alcohol)-protected reduction methods. The 3DOM LSMO support possessed a rhombohedral crystal structure and a surface area of 22–25 m²/g. MnOₓ and Au nanoparticles (NPs) (3.2–3.8 nm) were well dispersed on the surface of 3DOM LSMO. Catalytic performance of the samples for toluene oxidation was found to be well related to their surface adsorbed oxygen species concentrations and low-temperature reducibility. Among the as-prepared samples, 5.92Au/8MnOₓ/3DOM LSMO performed the best at a space velocity of 20 000 mL/(g h): the T₅₀% and T₉₀% (corresponding to toluene conversion of 50 and 90%) were 205 and 220 °C, respectively. The apparent activation energies (52.8–68.5 kJ/mol) obtained over the yAu/8MnOₓ/3DOM LSMO samples were much smaller than those (79.3–89.5 kJ/mol) obtained over the bulk LSMO supported counterparts. We believe that the excellent catalytic performance of 5.92Au/8MnOₓ/3DOM LSMO might be ascribed to the large surface area, high adsorbed oxygen species concentration, good low-temperature reducibility, and strong interaction between Au NPs or MnOₓ and 3DOM LSMO.
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