Poly urethane mixed matrix membranes for propylene and propane separation

Abstract

In this study, a dense mixed matrix membrane based on polyether ester urethane was fabricated using solution casting and dry phase inversion method. The mixed matrix membranes containing non-porous silica mineral nanoparticles, 4A zeolite nanoparticles, and ZIF-8 MOF nanoparticles with different loading. After characterized by FTIR, DLS, and SEM analysis, the membranes were used to separate propylene and propane. The presence of silica particles increased the micro phase separation, slightly reduced permeability, and increased selectivity. The presence of 4A and ZIF-8 particles increased the micro phase combination and permeability, and selectivity increased with the proper distribution of the particles in the polymer. A good distribution and adaptability of ZIF-8 in the polymer was observed because of the presence of the organic imidazolate ligands. The 4A particle shows inadequate compatibility to PU, and it reduces the membrane performance under loadings over 5% due to the formation of nonselective surrounding pores. In the best case, the membrane selectivity increased by 30% and its permeability increased to 133 barrer by adding 15 wt % of the ZIF-8 particle in the polyester-polyether urethane matrix.