Preparation and Characterization of Amine-functional SAPO-34 Mixed Matrix Membranes for CO2/CH4 Separation

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, polyetheresulfone mixed matrix membranes incorporated with small pore amine modified SAPO-34 were proposed for CO2 separation. SAPO-34 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. SEM images and FTIR analysis were used to characterize the filler particles and the synthesized membranes. SEM images also indicated that, there were appropriate distribution particles in the polymer matrix.The effects of filler loading (0-10 wt%), feed temperature (303-343 K) and feed pressure (0.5-4 bar) on CO2/CH4 selectivity of the MMMs were investigated. The results indicated that addition of amine-functional SAPO-34 in the casting solution enhanced the membrane gas permeance and CO2/CH4 ideal selectivity. For the membrane with 10 wt% of amine loading, selectivity was 17% higher than the membrane without functionalizing with amine Increasing the temperature from 303 to 343 K reduced selectivity around 25-30.5 %.