1. Kanagawa Academy of Science and Technology, 1583 Iiyama, Atsugi, Kanagawa 243-02, Japan, Tokyo Gas Co., Ltd., 7-7 Suehiro-cho, 1-Chome, Tsurumi-ku, Yokohama, Kanagawa 230, Japan, Department of Industrial Chemistry, Faculty of Engineering, Tokyo Metropolitan University, 1-1 Minami-Osawa, Hachioji, Tokyo 192-03, Japan, and Department of Applied Chemistry, Faculty of Engineering, University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113, Japan