Effect of SSZ‐13 Zeolite Loading and Synthesis Time on the CO 2 /N 2 Separation Performance of PDMS Mixed Matrix Membranes

ABSTRACT Mixed matrix membranes were produced by incorporation of SSZ‐13 zeolites into polydimethylsiloxane (PDMS) to assess the effect of filler properties and concentration on the CO 2 /N 2 separation efficiency compared to pure PDMS membranes. The membranes were produced with SSZ‐13 zeolites obtained by different hydrothermal synthesis times (1 or 4 days) and concentrations (0%–15%). All membranes were characterized and subjected to pure CO 2 and N 2 permeation tests. The highest performance was achieved through incorporation of 5% SSZ‐13 zeolites synthesized by 4‐day hydrothermal treatment, with 10.89 CO 2 /N 2 selectivity and CO 2 permeability of 2402.0 Barrer, 25.7% higher than pure PDMS. The increased performance was associated with higher diffusion rates of CO 2 when the zeolite was incorporated into the PDMS matrix. Higher percentages of SSZ‐13 led to lower separation capacity, decreased CO 2 permeability and CO 2 /N 2 selectivity. Using SSZ‐13 synthesized within 1 day resulted in membranes with reduced mechanical stability that were prone to tearing, reinforcing that proper selection of filler structural and surface properties is essential for manufacture of stable and reproducible mixed matrix membranes. Considering the trade‐off between permeability and selectivity typically observed in polymer membranes, this study highlights the potential of mixed matrix membranes to achieve incremental improvements on membrane‐based gas separation.