title: Selective hydrogenation of lactic acid to 1,2-propanediol over highly active ruthenium-molybdenum oxide catalysts.
abstract: Modification of Ru/C with a small amount of MoOx (RuMoOx /C) enhanced the catalytic activity in the hydrogenation of L-lactic acid to form 1,2-propanediol and maintained high selectivity. The turnover frequency based on the amount of Ru over the optimized RuMoOx /C catalyst (Mo/Ru molar ratio=1:16) was 114 h(-1) at 393 K, which was about 4 times higher than that over Ru/C. The same effect of MoOx was obtained over RuMoOx /SiO2 , although RuMoOx /SiO2 showed slightly lower activity than that of RuMoOx /C. RuMoOx /C achieved a high yield of 95 % in 18 h at 393 K and was applicable to various carboxylic acids to provide the corresponding alcohols in high yields. Modification with MoOx also brought about suppression of racemization and (S)-1,2-propanediol was obtained in high enantiomeric excess at 353 K. Based on kinetic analysis and characterization data, such as XRD, TEM, CO adsorption by a volumetric method, FTIR spectroscopy, and X-ray absorption spectroscopy, for RuMoOx /C and RuMoOx /SiO2 , the catalyst structure and reaction mechanism are proposed.
authors.affiliation: Department of Applied Chemistry, School of Engineering, Tohoku University, 6-6-07, Aoba, Aramaki, Aoba-ku, Sendai 980-8579 (Japan).
authors.forename: Yasuyuki
authors.initials: Y
authors.lastname: Takeda
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Shoji
authors.forename: Hideo
authors.initials: H
authors.lastname: Watanabe
authors.forename: Masazumi
authors.initials: M
authors.lastname: Tamura
authors.forename: Yoshinao
authors.initials: Y
authors.lastname: Nakagawa
authors.forename: Kazu
authors.initials: K
authors.lastname: Okumura
authors.forename: Keiichi
authors.initials: K
authors.lastname: Tomishige
mesh_terms: D000327:Adsorption; D002384:Catalysis; D006865:Hydrogenation; D007700:Kinetics; D019344:Lactic Acid / Q000737:chemistry*; D008982:Molybdenum / Q000737:chemistry*; D010087:Oxides / Q000737:chemistry*; D019946:Propylene Glycol / Q000737:chemistry*; D012428:Ruthenium / Q000737:chemistry*
chemical_list: D010087:Oxides; D019344:Lactic Acid; D019946:Propylene Glycol; D012428:Ruthenium; D008982:Molybdenum
keywords: carboxylic acids; enantioselectivity; hydrogenation; molybdenum; ruthenium