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

SAPO-34 membranes, synthesized by using multiple templates and reduced crystallization time, showed high CO 2 permeability for separating CO 2 /N 2 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 CO 2 permeance of 1.2 × 10 −6 mol/m 2 ·s·Pa (= 3500 GPU) with a CO 2 /N 2 separation selectivity of 32 for a 50/50 feed at 22 °C. At a feed pressure of 2.3 MPa (23 bar), the CO 2 flux was as high as 75 kg/m 2 h. The CO 2 /N 2 separations were also investigated in part by using vacuum permeate pumping, where the membrane showed a CO 2 permeance of 7.7 × 10 −7 mol/m 2 ·s·Pa and a CO 2 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 CO 2 /N 2 separation selectivity. The CO 2 permeance decreased by 37%, but it was recovered by calcination.