An analysis of the performance of membrane reactors for the water-gas shift reaction using gas feed mixtures

The water-gas shift (WGS) reaction in membrane reactors has been widely stu died by several authors. From these works, the increase of the CO conversio n above the equilibrium values appears to be possible when hydrogen is remo ved through the membrane. However, to date, this feasibility has been verified mostly when feeding pu re reagents to the reactor, although in an industrial context the feed norm ally contains several other compounds. The objective of this work has been to analyse the effect of the feed compo sition on the membrane reactor efficiency in order to determine the best co nditions in terms of CO conversion. At this purpose, experimental tests wit h mixtures of different compositions have been carried out in three differe nt systems of reaction: (1) traditional fixed-bed reactor; (2) membrane rea ctor with mesoporous ceramic membrane; (3) membrane reactor with palladium membrane. The experiments included permeation (for the membrane reactors) and reactio n tests. The experimental results obtained with the various systems of reaction have been compared. A mathematical model has been also formulated for the different type of rea ctors used in order to verify the experimental results obtained. From the work carried out it can be concluded that by using the palladium m embrane reactor it is possible to overcome the equilibrium conversion. More over, a complete conversion has been achieved for one of the mixtures fed t o the reactor. (C) 2000 Elsevier Science B.V. All rights reserved.