Carbon dioxide removal from methane by using polysulfone/SAPO-44 mixed matrix membranes

Abstract

Removal of CO2 in natural gas refining has currently been the only membrane based process practiced on a large scale operation. Despite the predominance of polymeric membranes in the CO2/CH4 separation, the tradeoff limitation in between membrane selectivity and permeability hinders a good separation performance of these membranes. Mixed matrix membranes can offer dramatic improvement to overcome this shortcoming. In this study, polysulfone mixed matrix membranes incorporated with small pore zeolite were proposed for CO2 separation. SAPO-44 zeolite was used as inorganic fillers to enhance gas selectivity. The asymmetric membrane structure was prepared using the phase inversion method in order to improve permeance. The effects of zeolite loading (5–20wt.%) on the membranes characteristic were studied using SEM and FTIR, while the gas transport properties were investigated using pure gas permeation tests of N2, CO2 and CH4 for each membrane. The most optimum sample is the membrane with 5wt.% of SAPO-44 loading, which exhibited improved CO2/N2 and CO2/CH4 selectivities of 22 and 25, respectively, compared to other samples. Devoid of any modification of filler phase, the addition of SAPO-44 inside polysulfone mixed matrix membranes has significantly enhanced CO2 separation performance.