Development and investigation of a multilayer PDMS/zeolite composite membrane for CO2 separation applications.

[Display omitted] • Coated PDMS on SSZ-13 layer to enhance separation performance. • Investigated PDMS concentration and coating time to optimize performance. • Enhanced CO 2 /CH 4 selectivity 20-fold, maintaining CO 2 permeance in single and mixed gas. • Achieved peak performance with ideal CO 2 /CH 4 selectivity of 428 and CO 2 permeance of 9.5 x 10-7 [mol/(m2sPa)] in single gas. • Obtained CO 2 /CH 4 selectivity of 290 and CO 2 permeance of 3.5 x 10-7 [mol/(m2sPa)] in mixed gas. This work aims to investigate and develop a concept for CO 2 separation based on PDMS/SSZ–13 (high-Si CHA) composite membranes. Firstly, an Al 2 O 3 support was coated with SSZ-13 zeolite layer, then to increase the performance of the membrane, a Polydimethylsiloxane layer was effectively deposited homogeneously to cover the cracks and defects of the zeolite layer. The results of single gas permeation measurements displayed a notable increase in ideal CO 2 /CH 4 selectivity up to 428 at the lowest PDMS concentration of 0.5 vol%. Moreover, a coating time of 10 min preserved CO 2 permeance while increasing CO 2 /CH 4 selectivity from 5 to 120. A twentyfold increase in CO 2 /CH 4 selectivity was noted with mixed gas permeation without a reduction in CO 2 permeance. Quantitative and qualitative microscopic analyses were also carried out on the coated membrane to better understand its morphology and microstructure. The outcomes indicated that PDMS layer decreased the permeation of N 2 and CH 4 and enhanced surface affinity toward CO 2 , resulting in reduced defects in the zeolite membranes and enhanced selectivity for CO 2 /N 2 and CO 2 /CH 4. [ABSTRACT FROM AUTHOR]