Ultra-permeable high-selective SAPO-34 membranes for efficient CO2 capture

Ultra-permeable SAPO-34 membranes with membrane thickness of 0.8-1.2 mu m were reproducibly fabricated using diluted mother liquids with H2O/Al2O3 ratios of 300 and 450. The orientation and thickness of the membranes were greatly affected by mother liquid dilution. Thickness-even SAPO-34 membranes were reproducibly prepared in a large synthesis time window, indicating that membrane synthesis had good robustness and it is suitable to the scale-up fabrication. The membranes prepared at H2O/Al2O3 ratio of 450 displayed ultrahigh CO2 permeances of (1.0-1.3) x 10(-5) mol (m(2) s Pa)(-1) (-30000-37000 GPU) and CO2/CH4 selectivities of (56-126) at 298 K and 0.2 MPa pressure drop. The typical membrane also displayed CO2 permeance of 7.6 x 10(-6) mol (m(2) s Pa)(-1) (-23000 GPU) and CO2/N-2 selectivity of 35 for an equimolar CO2/N-2 mixture. The separation performance of these thin SAPO-34 membranes was far beyond that of most reported membranes. Such CO2 permeances of the membranes are 200-350 times higher than that of commercial polyimide membranes. The membranes shows great potentials for CO2 capture from natural and flue gases.