Performance of hydrophobic and hydrophilic silica membrane reactors for the water gas shift reaction

Abstract

In this study, a novel molecular sieve silica (MSS) membrane packed bed reactor (PBR) using a Cu/ZnO/Al2O3 catalyst was applied to the low-temperature water gas shift reaction (WGS). Best permeation results were H2 permeances of 1.5×10-6 mol s-1 m-2 Pa-1, H2 /CO2 selectivities of 8 and H2/N2 selectivities of 18. It was shown that an operation with a sweep gas flow of 80 cm3 min-1, a feed flow rate of 50 cm3 min-1 and a H2O/CO molar ratio of one at 280 °C reached a 99% CO conversion. This is well above the thermodynamic equilibrium and achievable PBR conversion. Hydrophilic membranes underwent pore widening during the reaction while hydrophobic membranes indicated no such behaviour and also showed increased H2 permeation with temperature, a characteristic of activated transport. © 2003 Elsevier Science B.V. All rights reserved.