Growth of High-Quality, Thickness-Reduced Zeolite Membranes towards N2 /CH4 Separation Using High-Aspect-Ratio Seeds.

Greatly improved zeolite membranes were prepared by using high-aspect-ratio zeolite seeds. Slice-shaped seeds with a high aspect ratio (AR) facilitated growth of thinner continuous SAPO-34 membranes of much higher quality. These membranes showed N2 permeances as high as (2.87±0.15)×10(-7)  mol m(-2)  s(-1)  Pa(-1) at 22 °C while maintaining a decent N2 /CH4 selectivity (9-11.2 for equimolar mixture). On the basis of these thinner high-quality SAPO-34 membranes, fine-tuning the local crystal structure by incorporating more silicon further increased the N2 permeance by 1.4 times without sacrificing the N2 /CH4 selectivity. We expect that application of large AR zeolite seeds might be a viable strategy to grow thin high-quality zeolite membranes. In addition, fine-tuning of the crystal structure by changing the crystal composition might be a feasible way for further improving the separating performance of high-quality zeolite membranes.