High-Flux SAPO-34 Membrane for CO2/N2 Separation

Abstract

SAPO-34 membranes, synthesized by using multiple templates and reduced crystallization time, showed high CO2 permeability for separating CO2/N2 mixtures up to 230 °C. At a trans-membrane pressure drop of 138 kPa and an atmospheric pressure in the permeate side, one such membrane had a CO2 permeance of 1.2 × 10−6 mol/m2·s·Pa (= 3500 GPU) with a CO2/N2 separation selectivity of 32 for a 50/50 feed at 22 °C. At a feed pressure of 2.3 MPa (23 bar), the CO2 flux was as high as 75 kg/m2 h. The CO2/N2 separations were also investigated in part by using vacuum permeate pumping, where the membrane showed a CO2 permeance of 7.7 × 10−7 mol/m2·s·Pa and a CO2 permeate concentration of 93% for an equimolar feed at 22 °C. At 105 °C, adding 8% water vapor to the feed had almost no effect on the CO2/N2 separation selectivity. The CO2 permeance decreased by 37%, but it was recovered by calcination.