酸化亜鉛の表面構造とプロピレン酸化活性

概要

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The relation between surface structure and catalytic properties for propylene oxidation was studied using three kinds of zinc oxide particles: needle-like, granular and plate-like. Needlelike ZnO was obtained by the oxidation of zinc vapor. The needle axis was found to be parallel to c axis of the crystal, while the surface of needle was slightly tapered. The particles of this shape were found to be unstable and change into granular shape by the prolonged heat treatment at 500-600℃. From this observation, granular ZnO was prepared by heating needle-like ZnO at 600℃ for 3 hr. Plate-like ZnO was obtained by the thermal decomposition of mist of zinc nitrate solution at 600℃. Electron diffraction analysis indicated that the plane of this sample was perpendicular to c axis. Needle-like and granular ZnO showed high activities for allylic oxidation to benzene under such a condition as resulting in the reduction of catalyst surface. On the other hand, platelike ZnO with the plane perpendicular to c axis was less active for benzene formation. Since not only granular ZnO but also tapered needle-like ZnO has the plane parallel to c axis more than plate-like sample, these results suggest that the active site for allylic oxidation may be on the plane (1010) or (1120) reduced partially.
長崎大学工学部,Faculty of Engineering, Nagasaki Universityの論文