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Abstract:The production of γ-valerolactone (GVL) directly from biomass-based levulinic acid (LA) and formic acid (FA) without extra hydrogen source is attractive but challenging, due to the requirement of a highly active and stable catalyst. In present work, Au/Ce x Zr 1−x O 2 with various Ce/Zr ratios were prepared as the catalyst for GVL production from LA with the equivalent molar FA, and characterized by XRD, Raman-spectra, BET, NH 3 -TPD, TEM and XPS. It was found that the doped Ce in Au/Ce x Zr 1−x O 2 catalyst could improve the reduction of Au 3+ to metallic Au 0 , and also promoted the dispersion of Au 0 , yielding uniform Au 0 nanoparticles with a small average particle size of about 2.4 nm, thus enhancing both the decomposition of FA to CO-free H 2 and the hydrogenation of LA. Meanwhile, a certain amount of doped Ce (x ≤ 0.4) could facilitate the formation of tetragonal phase (the most desired structure on LA conversion to GVL), and increase the amount of weak and medium-strength acidic sites of catalyst, thereby promoting the dehydration reaction of the intermediate derived from LA hydrogenation. Au/Ce 0.4 Zr 0.6 O 2 catalyst exhibited the best catalytic activity, achieving 90.8% of LA conversion and 83.5% of GVL yield (TON = 2047.8), with good recyclability, and the activity showed no obvious change after 5 runs.

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A mesoporous silica-supported molybdenum oxide catalyst with a cerium(Ce) modifier was prepared by in situ synthesis and used in a hydrogen peroxide (H2O2) system for the desulfurization of dibenzothiophene (DBT), benzothiophene (BT), and 4,6-dimethyldibenzothiophene (4,6-DMDBT) fuel oils. The catalytic performance of the catalyst was studied. The catalyst was characterized by Fourier Transform Infra-Red(FT-IR), X-ray diffraction (XRD), Brunner−Emmet−Teller (BET), and X-ray Photoelectron Spectroscopy(XPS). The influences of m(catalyst)/m(fuel oil), v(H2O2)/v(fuel oil), reaction temperature, and reaction time were investigated. The catalyst had excellent catalytic oxidation desulfurization performance under moderate operational conditions. The catalytic performance was in the order DBT > 4,6-DMDBT > BT. The kinetic analysis results showed that the reaction was a pseudo first-order kinetics process and the apparent activation energies of DBT, BT, and 4,6-DMDBT were 46.67 kJ/mol, 56.23 kJ/mol, and 55.54 kJ/mol, respectively. The reaction products of DBT, BT, and 4,6-DMDBT were DBTO2, BTO2, and 4,6-DMDBTO2, respectively. The recycling experiments indicated that DBT, BT, and 4,6-DMDBT removal could still reach levels of 94.0%, 63.0%, and 77.9% after five cycles.

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TiO2 photocatalysts doped by Fe3+ with different contents were prepared by adsorption phase synthesis. The influence of Fe3+ doping with various concentrations on the crystallization of TiO2 was explored by XRD. Then photodegradation experiments of methyl-orange were employed to evaluate the activity of these photocatalysts. The results indicated that the crystallization of TiO2 was restricted after doping, due to replacement of Ti4+ in TiO2 lattice structure by Fe3+ ions. And the restriction became stronger with doping concentration of Fe3+ ions increasing. Since radius of Fe3+ was close to Ti4+, the restriction of Fe3+ doping on crystallization of TiO2 was so stronger that the photocatalytic activity of most TiO2 doped with Fe3+ ions was lower than that of TiO2 without doping.