Pressure Effects upon Heterogeneous Liquid Phase Catalysis -Mutarotation of α-D-Glucose over an Alumina Catalyst-

DOI Web Site
  • SATO Masanori
    Department of Molecular Chemistry and Engineering, Faculty of Engineering, Tohoku University
  • NAKATANI Jiro
    Department of Molecular Chemistry and Engineering, Faculty of Engineering, Tohoku University
  • OZAWA Sentaro
    Department of Molecular Chemistry and Engineering, Faculty of Engineering, Tohoku University
  • OGINO Yoshisada
    Department of Molecular Chemistry and Engineering, Faculty of Engineering, Tohoku University

Bibliographic Information

Other Title
  • 液相不均一系触媒反応に対ずる圧力効果アルミナ触媒上でのα-D-グルコース変旋光反応
  • Pressure effects upon heterogeneous liquid phase catalysis - Mutarotation of .ALPHA.-D-glucose over an alumina catalyst.

Abstract

Effects of pressure upon the rate of mutarotation of α-D-glucose to β-D-glucose in dimethyl sulfoxide over an alumina catalyst have been studied at a constant temperature of 40±0.1°C under various pressures in the range of 0.1-90 MPa. The initial α-D-glucose concentration was varied in the range of 2.8-12×10-2 mol/dm3.<BR>It was concluded that the same surface reaction proce eds in the pressure range examined, though an increase of the pressure retarded the reaction rate. Thus the kinetic parameters Kα(α-D-glucose adsorption coefficient), Kβ(β-D-glucose adsorption coefficient), k1 (the rate constant for the surface forward reaction), and k2 (the rate constant for the surface backward reaction) were evaluated as a function of pressure.<BR>The pressure dependences of both Kα, and Kβ were very small (the volume changes ΔVα=ΔVβ=0 cm3/mol), suggesting that the desolvation from anionic adsorption sites compen sates a negative volume change on adsorption. On the other hand, fairly large positive activation volumes were obtained; V1≠=22±4 cm3/mol (surface forward reaction) and V2≠=20+3 cm3/mol (surface backward reaction). This is in sharp contrast to the negative activation volume for the homogeneous catalysis and suggests that the transition state of the heterogeneous reaction is quite different from that of the homogeneous reaction. A simple model calculation has shown that a formyl group rotation step which requires a vacant hole of 22 cm3/mol is mainly responsible for the most of the observed positive activation volume.

Journal

  • NIPPON KAGAKU KAISHI

    NIPPON KAGAKU KAISHI 1988 (11), 1794-1799, 1988-11-10

    The Chemical Society of Japan

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