Modelling gas purification systems employing molecular sieve silica membranes

Abstract

In this work, we simulate the transient behaviour of gas purification systems employing silica derived membranes and formulate a model that is capable of predicting this transient behaviour in the presence of a CO 2 and H 2, both as single gases and as a binary gas mixture. The model is based on continuity and assumes that the membrane properties do not change between single gas and mixed gas cases. Based on these properties, the complete characterization of transient membrane performance is obtained thereby providing an explanation based upon driving forces for very significant differences between single and mixed gas measurements. The simulated results are validated with independent mixed gas experiments and are then extended to analyse the difference in performance for a gas separation system with mixed gas feed using membranes with at least one order of magnitude difference in selectivity based on single gas permeations. The model also allows simulation for membranes complying with temperature dependency mechanism. Our results show that the increase in performance of the system for mixed gas feed is not commensurate with the increase in the selectivity based on single gas permeations.