Effect of the Si/Al Ratio of the Seeds in the Preparation of Supported SSZ-13 Membranes with a Secondary Growth Method

The effect of the silicon-to-aluminum ratio (SAR) of SSZ-13 seeds on the preparation of SSZ-13 membranes through a secondary growth method was explored. Nanosized SSZ-13 seeds with four types of SARs (3.4, 5.7, 11, and 24) were prepared. The growth process revealed the formation of the SSZ-13 membrane via the epitaxial growth route with seeds of low SARs (3.4, 5.7, and 11) and the growth of the SSZ-13 membrane via the dissolution–recrystallization route with seeds of high SARs (24). Both in zeolite powder preparation and membrane preparation experiments, faster growth of the SSZ-13 crystal was obtained with seeds of lower SARs, indicating that the seeds with lower SARs showed a higher inductive effect on the growth of the SSZ-13 crystal. Thus, the SSZ-13 membranes synthesized with low-SAR (3.4) seeds showed good compactness and high separation performance and reproducibility. Finally, the membrane showed a high flux of 1.32 kg·m–2·h–1 and a good separation factor of >10000 for 10/90 wt % water/ethanol mixtures at 60 °C. The results above revealed that the SSZ-13 membrane obtained with seeds of a low SAR (3.4) showed a potential value toward industrial scale-up.