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CuOx/ZrO2 samples prepared by adsorption from copper solutions or by impregnation were characterized by means of FTIR, XPS, ESR, DRS, volumetric CO adsorption, and redox cycles with H2 and O2. In samples prepared by adsorption, the maximum copper uptake corresponded to an extended plateau at 2.5 atoms nm-2. In as-prepared samples, isolated CuII species were in a distorted octahedral configuration, and in samples heated in dry O2 at 773 K, in a square-pyramidal configuration. Water vapor adsorption transformed the latter species into distorted octahedral complexes. In all samples, heating in O2 at 773 K anchored copper to the zirconia surface. All copper was present as CuII. Evacuation of these samples at 773 K caused no copper reduction, whereas heating with H2 above 450 K reversibly reduced CuII to metal copper. Evacuation of as-prepared samples differed according to how samples were prepared. In particular, evacuation of samples prepared from Cu−acetylacetonate or Cu−acetate reduced CuII to CuI at 473 K...

The transformation of glucose into valuable biochemicals was carried out on different MCM-41-supported metallic and bimetallic (Co, Co-Fe, Co-Mn, Co-Mo) catalysts and under different reaction conditions (150 &deg, C, 3 h, 200 &deg, C, 0.5 h, 250 &deg, C, 0.5 h). All catalysts were characterized using N2 physisorption, Temperature Programmed Reduction (TPR), Raman, X-ray Diffraction (XRD) and Temperature Programmed Desorption (TPD) techniques. According to the N2-physisorption results, a high surface area and mesoporous structure of the support were appropriate for metal dispersion, reactant diffusion and the formation of bioproducts. Reaction conditions, bimetals synergetic effects and the amount and strength of catalyst acid sites were the key factors affecting the catalytic activity and biochemical selectivity. Sever reaction conditions including high temperature and high catalyst acidity led to the formation mainly of solid humins. The NH3-TPD results demonstrated the alteration of acidity in different bimetallic catalysts. The 10Fe10CoSiO2 catalyst (MCM-41 supported 10 wt.%Fe, 10 wt.%Co) possessing weak acid sites displayed the best catalytic activity with the highest carbon balance and desired product selectivity in mild reaction condition. Valuable biochemicals such as fructose, levulinic acid, ethanol and hydroxyacetone were formed over this catalyst.