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Ru nanoparticles entrapped in ordered mesoporous carbons (CMK-3) served as an efficient and reusable catalyst for liquid-phase hydrogenation of benzaldehyde and its derivatives under our tested conditions (medium hydrogen pressure, room temperature, water as solvent). The Ru nanoparticles can be well stabilized by CMK-3 ordered mesoporous carbons so that the Ru leaching was below the detection limit of ICP-AES. Therefore, the Ru/CMK-3 catalyst can be used for at least five times without distinct loss in activity or selectivity for the hydrogenation of benzaldehyde. It is worthy of note that the Ru/CMK-3 catalyst was more efficient than the commercial Ru/C and homemade Ru/AC catalyst for the liquid-phase hydrogenation of benzaldehyde. The Ru/CMK-3 catalyst can also catalyze the liquid-phase hydrogenation of nitrobenzene and its derivatives with high conversions and excellent selectivities under optimal conditions. Graphical Abstract: [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Highlights: [•] MIL-101 metal–organic frameworks as support for Pt nanoparticles. [•] Catalysts are effective for heterogeneous asymmetric hydrogenation of α-ketoesters. [•] Catalysts can be reused several times without distinct loss in activity or ee value. [•] Pt nanoparticles can be well stabilized by MIL-101 metal–organic frameworks. [ABSTRACT FROM AUTHOR]

Solid-state grinding, ultrasonic impregnation and conventional impregnation methods were adopted to synthesize mesoporous composites Al 2 O 3 @SBA-15 supported Pt catalysts for chiral hydrogenation of ethyl 2-oxo-4-phenylbutyrate after modified with cinchonidine. Compared with Pt/SBA-15 or Pt/alumina catalyst, Pt/Al 2 O 3 @SBA-15 catalysts afforded better results when alumina loading in Al 2 O 3 @SBA-15 composites reached above 15 wt.%. Nevertheless, the catalytic performance of Pt/Al 2 O 3 @SBA-15 catalysts was affected by preparation methods for Al 2 O 3 @SBA-15 composites. Ultrasonic impregnation of SBA-15 with an aqueous solution of aluminum nitrate led to uniformly dispersed Al 2 O 3 @SBA-15 composites and then enhanced the interaction between SBA-15 silica and alumina. Correspondingly, the Pt/Al 2 O 3 @SBA-15 catalyst prepared by this method showed the best results (up to 11,928 h −1 TOF and 87.9% ee) and could be reused for several times. Based on the spectroscopic characterizations, we deduced that the acidity of the composites, the Pt particle size and dispersion, and the electronic properties of Pt particles played vital roles in determining the catalytic performance. [ABSTRACT FROM AUTHOR]

Abstract: A series of TiO2@SBA-15 composites with different TiO2 loadings have been synthesized through hydrolysis of tetrabutyl orthotitanate via a facile sol–gel method in the presence of SBA-15 mesoporous silica. The TiO2@SBA-15 composites retain the mesostructure of the SBA-15 host, and TiO2 is highly dispersed and uniformly coated. The TiO2@SBA-15 composites serve as remarkable supports for Pt nanoparticles, which can be applied efficiently to the liquid-phase hydrogenation of benzaldehyde, its derivatives, and other unsaturated compounds under mild conditions. Of particular note is that the Pt/TiO2@SBA-15 catalysts can be reused several times without distinct loss in activity or selectivity. The more electron-deficient surface state, together with the structural and physicochemical features of Pt/TiO2@SBA-15 catalysts, would improve the catalytic activity and reusability toward the liquid-phase hydrogenation of unsaturated compounds. [Copyright &y& Elsevier]