Separation of alcohols and alcohols/O 2 mixtures using zeolite MFI membranes Elena Piera b , Anne Giroir-Fendler a , Jean Alain Dalmon a , Hichem Moueddeb a , Joaquõ Ân Coronas b , Miguel Mene Ândez b , Jesu Âs Santamarõ Âa b,* a Institut de Recherches sur la Catalyse, C.N.R.S., Avenue Albert Einstein, 2, 69626 Villeurbanne, France b Department of Chemical and Environmental Engineering, Faculty of Science, University of Zaragoza, 50009 Zaragoza, Spain Received 6 October 1997; received in revised form 2 December 1997; accepted 2 December 1997 Abstract 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 -alumina supports, while in the other the zeolitic material was mainly present in the porous structure of the -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 ef®ciently. 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. # 1998 Elsevier Science B.V. Keywords: Separation; Alcohols/O 2 mixtures; Zeolite MFI 1. Introduction The ®eld of inorganic membranes has been the subject of intensive research in the last two decades, as indicated by the publication of several interesting reviews on this area [1±4]. Many laboratories are today involved in the preparation and characterization of more selective, continuous microporous mem- branes (with pore size smaller than 2 nm). Zeolite membranes belong to this kind of microporous mem- branes with pores of molecular size. As a conse- quence, they are able to separate organics with close boiling points [5], with comparable (and often greater) effectiveness than traditional distillation. They can also separate molecules with the same molecular weight [6±9], something impossible to achieve with mesoporous membranes where transport is governed by Knudsen diffusion. The hydrothermal synthesis of zeolites on porous alumina and porous stainless steel has been reported for silicalite [6±8,10,11], ZSM-5 [9,12,13], mordenite [14], zeolite A [15,16], ferrierite [17], zeolite Y [18,19] and the pseudozeolite SAPO-5 [20]. Although tubular membranes are more suitable than ¯at ones Journal of Membrane Science 142 (1998) 97±109 *Corresponding author. Tel.: +34 9 76 76 11 53; fax: 34 9 76 76 21 42; E-mail: iqcatal@posta.unizar.es 0376-7388/98/$19.00 # 1998 Elsevier Science B.V. All rights reserved. PII S0376-7388(97)00321-9