Elucidation of the Catalytic Pathway for the Direct Conversion of Furfuryl Alcohol into γ-Valerolactone over Al2O3-SiO2 Catalysts.

The one-pot conversion of furfuryl alcohol (FA) into GVL was investigated over the sol-gel-synthesized Al2O3-SiO2 (AlSi) catalysts with various Al2O3 loadings (0.2-10 wt %) and commercial zeolites including MFI-1, H-ZSM5, H-beta, and HY-15 in a batch reactor under mild reaction conditions (130 °C, 1 bar N2, and 15-120 min). The reaction pathways depend largely on the acid properties of the catalysts, especially the types of Bronsted (B) and Lewis (L) acid sites. A tandem alcoholysis/hydrogenation/cyclization sequence is dominant on the AlSi catalysts (Al ≥ 4%) and all the zeolites except MFI-1, resulting in complete conversion of FA and GVL with an yield 64-75% with IPL as the major side-product, regardless of the differences in their B/L ratios 0.06-1.35. In the absence of B acid sites (i.e., 0.2% AlSi and MFI-1 catalysts), FA could be straightforwardly converted into GVL on the weak Lewis acid sites from the isolated silanol groups using 2-propanol as a hydrogen source. The AlSi catalysts are promising tunable catalysts for FA conversion with good recyclability.

Liquid-phase hydrogenation of phenylacetylene over the nano-sized Pd/TiO2 catalysts.

Understanding the mechanisms of metal-support interaction and/or adhesion and growth of the metal particles is important not only in the field of catalysis but also the design of advanced nanostructure materials. In the present work, the strong metal-support interaction (SMSI) effect occurred on the Pd/TiO2 catalysts synthesized by the sonochemical method when reduced at 500 degrees C whereas the ones prepared by the conventional impregnation resulted in sintering of Pd0 particles instead. The presence of SMSI was correlated to the amount of oxygen vacancies or Ti3+ defective sites. Smaller Pd0 particles with more uniform size distribution on the sonochemical-derived catalysts may promote hydrogen spillover from Pd0 surface to TiO2 support so that the reduction of Ti4+ to Ti3+ occurred, resulting in the SMSI. As a consequence, the catalysts exhibited improved catalytic performances in the liquid-phase selective hydrogenation of phenylacetylene to styrene.