The chemical valve membrane: a new concept for an auto-regulation of O-2 distribution in membrane reactors

An original method is proposed in this work to regulate the alkane/O-2 rati o in catalytic membrane reactors for oxidative reactions. The concept is ba sed on the use of a "chemical valve membrane" as O-2 distributor. V2O5 is a n attractive key constituent for such a membrane because of its reversible red/ox behavior (V2O5/V2O3) and related textural variations able to regulat e membrane permeance. This work shows how membrane permeability can be cont rolled by the red/ox characteristics of the gas phase. We studied the influ ence of the reducing gas on the evolution of membrane permeance in relation to the membrane weight changes, up to 500 degreesC. The red/ox kinetics ha ve been compared using a series of reducing gases (i-C4H10, C3H8, C2H6, C2H 4, CH4 and H-2). Finally, we showed how the permeability of such a membrane , when used as an O-2 distributor in a reactor configuration, is controlled by the red/ox characteristics of the gas phase (i.e. by the alkane/O-2 rat io in the reactor). (C) 2001 Elsevier Science B.V. All rights reserved.