Structure of the Supported Uranium Oxide Catalytic and Catalytic Activity for Oxidation of Carbon Monoxidet

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  • NOZAKI Fumio
    Department of Industrial Chemistry, Faculty of Engineering, Chiba University
  • KOBAYASHI Masayuki
    Department of Industrial Chemistry, Faculty of Engineering, Chiba University
  • YOSHIDA Setsuko
    Department of Industrial Chemistry, Faculty of Engineering, Chiba University

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Other Title
  • 担体付酸化ウラン触媒の構造と一酸化炭素酸化活性

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In order to reveal the catalytic properties of uranium oxide-alumina and uranium oxidesilica, various investigations on the structure of catalyst and the activity for catalytic oxidation of CO were performed.<BR>The experimental results gave the following conclusions.<BR>(1). As shown in Fig.3, the oxidative activity of the catalyst supported on silica is remarkably low, comparing with the catalyst supported on alumina. This is due mainly to the fact that uranyl compound used as a starting material for the catalyst preparation hardly decomposes to uranium oxide, contrasting with the case in which uranyl compound is supported on alumina.<BR>(2) The reaction rates of CO oxidation by the catalyst supported on alumina or the catalyst without carrier can be expressed approximately as the first order with CO pressure and the zeroth order with 02 pressure. Apparent activation energy is nearly equal to be 25 kcal/mol for the former catalyst and 18 kcal/mol for the latter catalyst.<BR>(3) The following reaction scheme has been postulated, <BR>U308 + CO A > U307 + CO, (catalyst reduction step)<BR>U307 + 1/2 02 --+ U808 (catalyst oxidation step)<BR>i. e., the reaction proceeds by oxidation-reduction cycles, in which the catalyst reduction step is the rate-determining process.<BR>(4) Generally speaking, alumina and silica trend to combine with uranium oxide or uranyl compound during the course of catalyst preparation. The catalysts calcined up to 500°C contains various chemical species of uranium, the catalytic activity levels of which are different. At present it was evident that the active components were limited only to uranium oxide on alumina and uranium oxide-alumina compound.

Journal

  • NIPPON KAGAKU KAISHI

    NIPPON KAGAKU KAISHI 1972 (1), 26-33, 1972-01-10

    The Chemical Society of Japan

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