1. Department of Applied Chemistry, Muroran Institute of Technology, Mizumoto, Muroran, 050-8585 Japan
2. Environmental Technology Centre, Department of Chemical Engineering, UMIST, P.O. Box 88, Manchester M60 1QD, U.K.
3. Centre for Microporous Materials, Department of Chemistry, UMIST, P.O. Box 88, Manchester M60 1QD, U.K.