Mixed matrix membranes using SAPO-34/polyetherimide for carbon dioxide/methane separation

Abstract

Mixed matrix membranes (MMMs) are hybrid materials prepared by dispersing inorganic particles in a polymeric matrix and are attracting increasing attention for the separation of CO2/CH4 mixtures. The zeolite SAPO-34 and polyetherimide were selected as the inorganic filler and the polymeric matrix for the synthesis of the supported MMMs. Two polymer solvents, dichloroethane (DCE) and N-methyl-2-pyrrolidone (NMP), were investigated for the preparation, and the DCE solvent resulted in a membrane with better CO2/CH4 selectivity. Various SAPO-34 amounts from 0 to 10wt% were dispersed in the polymer precursor which was dissolved in DCE. The membrane with 5wt% SAPO-34 content presented the highest performance with a CO2 permeance of 4×10−10molm−2s−1Pa−1 and a CO2/CH4 ideal selectivity of 60. Based on mixed gas permeances and time-lag measurements, the separation of CO2 and CH4 was found to be dominated by the difference in the gas solubilities. The SAPO-34 decreased CH4 transport by increasing its diffusion pathway. Particle agglomeration was observed at 10 wt% zeolite loading in the polymeric matrix.