Optimization and performance studies of PES/SAPO-34 membranes for CO2/N2 gas separation

SAPO-34 nanocrystals were prepared and used as inorganic filler in polyethersulfone (PES) membranes. The influence of preparation conditions on permeation properties of CO2 and N2 gases and CO2/N2 selectivity were studied to achieve the highest separation performance possible for this mixed-matrix membrane. Gas permeation properties of PES/SAPO-34 MMMs with different contents of SAPO-34, PES and initial film thickness were investigated according to a full factorial design of experiments (DOE). The permeation tests and DOE results revealed that the optimized conditions to maximize the selectivity for PES/SAPO-34 are: composition of 18.5 wt% of SAPO-34, 15 wt% of PES, and a casted film thickness of 400 μm resulting in a CO2/N2 selectivity of 30.85. The findings showed that a multivariable model was validated and able to predict the selectivity with determination coefficient R2 of 0.969 and the results are in accordance with values presented in literature for PES/SAPO-34 membranes. An economic analysis shows that the commercial grade price for the optimized membrane is EUR 9.43/m2 which represents around 2.2 times cheaper than polymeric commercial membranes.