A simulation study of the effect of operating and design parameters on the performance of a water gas shift membrane reactor

The goal of this work is to understand the effect of the relative values of membrane permselectivity, permeation flux and reaction rate on the performance of a water gas shift membrane reactor. This was achieved by simulating the operation of an isothermal tube–shell reactor. Its performance was evaluated based on the CO conversion and H2 recovery, as well as the permeate and retentate H2 molar fractions. The maximum enhancement of CO conversion has been observed when the Damkhöler number (Da) is almost equal to the permeation number (Pe). Improvements in CO conversion can be achieved even when membranes with relatively low permselectivity values (∼10) are used. Further increase of permselectivity primarily increased the purity of the H2 rich stream. The utilization of CO2 selective instead of H2 selective membranes could improve CO conversion only if the CO2 content of the feed is higher than that of H2. Finally, simulations using rate expressions that correspond to different detailed reaction mechanisms resulted only in slight differences in reactor performance.