Evaluation of porous ceramic membranes as O2 distributors for the partial oxidation of alkanes in inert membrane reactors

This study aimed to investigate the effects of different gas transport regime on the O-2 distribution properties of porous ceramic membranes in inert membrane reactors. Three porous ceramic membranes, with different porous structure (microporous MFI zeolite, mesoporous SiO2 and meso-macroporous AlPO4 membranes), have been synthesised and characterised. The membranes were evaluated as O-2 distributors in an inert membrane reactor under typical operating conditions used for the partial oxidation of alkanes before placing the catalyst bed. The C3H8 oxidation was chosen as a test reaction. The performance of the three membranes as O-2 distributors, whose permeance are comparable, were evaluated by their ability (1) to control the O-2 partial pressure 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 temperature on the membrane performance were also studied. On the basis of the above mentioned experimental conditions and criteria, the AlPO4 membrane, reported here for the first time, is clearly the most efficient membrane as porous O-2 distributor. This outstanding property arises from its porous structure which allows a viscous flow transport and a high barrier effect, (C) 2001 Elsevier Science B.V. All rights reserved.