Evaluation of porous ceramic membranes as O-2 distributors for the partialoxidation of alkanes in inert membrane reactors

This study aimed to investigate the effects of different gas transport regi me on the O-2 distribution properties of porous ceramic membranes in inert membrane reactors. Three porous ceramic membranes, with different porous st ructure (microporous MFI zeolite, mesoporous SiO2 and meso-macroporous AlPO 4 membranes), have been synthesised and characterised. The membranes were e valuated as O-2 distributors in an inert membrane reactor under typical ope rating conditions used for the partial oxidation of alkanes before placing the catalyst bed. The C3H8 oxidation was chosen as a test reaction. The per formance of the three membranes as O-2 distributors, whose permeance are co mparable, were evaluated by their ability (1) to control the O-2 partial pr essure in the tube side and (2) to limit the back-diffusion of C3H8 to the shell side by application of a transmembrane pressure. The effects of tempe rature on the membrane performance were also studied. On the basis of the a bove mentioned experimental conditions and criteria, the AlPO4 membrane, re ported here for the first time, is clearly the most efficient membrane as p orous O-2 distributor. This outstanding property arises from its porous str ucture which allows a viscous flow transport and a high barrier effect, (C) 2001 Elsevier Science B.V. All rights reserved.