Separation of alcohols and alcohols/O2 mixtures using zeolite MFI membranes

Two different types of supported silicalite membranes were employed for the separation of alcohols and alcohols/O-2 mixtures: in one of them the zeolite material was deposited on the top of the gamma-alumina supports, while in the other the zeolitic material was mainly present in the porous structure of the alpha-alumina supports. While both kinds of membranes were able to separate the above mixtures, the second type of membranes having the zeolite material inside the support performed more efficiently. The maximum selectivity reported in this work is 7415 for the ethanol/O-2 separation in an ethanol/methanol/O-2 mixture. For a better understanding of the separation mechanism, the performance of both zeolite membranes was compared to that of a mesoporous silica membrane. Also, the adsorption of methanol and propanol on silicalite crystals was measured using a microbalance. (C) 1998 Elsevier Science B.V.