Preparation and catalytic performance of Ag, Au, Pd or Pt nanoparticles supported on 3DOM CeO2-Al2O3 for toluene oxidation

Three-dimensionally ordered macro-/mesoporous 26.9 wt% CeO2-Al2O3 (denoted as 3DOM 26.9CeO(2)-Al2O3)-supported noble metal nanocatalysts (xM/3DOM 26.9CeO(2)-Al2O3, x=0.27-0.81 wt%; M = Au, Ag, Pd, and Pt) were prepared using the polymethyl methacrylate-templating and polyvinyl pyrrolidone- or polyvinyl alcohol-protected reduction methods, respectively. It is shown that the xM/3DOM 26.9CeO(2)-Al2O3 samples displayed a high-quality 3DOM architecture with a bimodal pore (macropore size = 180-200 nm and mesopore size = 4-6 nm) structure and a surface area of 102-108 m(2)/g, with the noble metal nanoparticles (3-4 nm in size) being highly dispersed on the 3DOM 26.9CeO(2)-Al2O3 surface. The 0.27Pt/3DOM 26.9CeO(2)-Al2O3 sample performed the best (T-90% = 198 degrees C at space velocity = 20,000 mL/(g h)) for toluene oxidation. The addition of moisture to the feedstock induced a positive effect on catalytic activity. The apparent activation energies obtained over the xM/3DOM 26.9CeO(2)-Al2O3 samples were in the range of 46-100 kJ/mol, with the 0.27Pt/3DOM 26.9CeO(2)-Al2O3 sample possessing the lowest apparent activation energy. It is concluded that the good catalytic performance of 0.27Pt/3DOM 26.9CeO(2)-Al2O3 was associated with its higher adsorbed oxygen species concentration, better low-temperature reducibility, and stronger interaction between Pt and 3DOM 26.9CeO(2)-Al2O3 as well as the unique bimodal porous structure. (C) 2015 Elsevier B.V. All rights reserved.