Self-limiting growth of thin dense LTA membranes boosts H₂ gas separation performance

The preparation of dense LTA-type zeolite membranes with a thickness in the sub-micron range remains extremely difficult due to their high electronegativity. Herein, thin dense LTA membranes were prepared through the secondary growth of nano LTA seeds in a highly reactive gel. The uniformity of the nano seed layer contributed to the growth of continuous membranes. The self-limiting growth of the zeolite membrane layer was controlled by the synergistic effect of using a highly reactive gel and nano seeds, and resulted in the preparation of thin membranes. Optimized aging times of the gel further enhanced the packing density of the membranes via an efficient intergrowth of the zeolite crystals. This is the first time to obtain single-phase LTA membranes with a thickness of less than 1 mu m. The similar to 470 nm-thick membrane exhibited a H-2 permeance of 1.5 x 10(-6) mol m(-2) s(-1) Pa-1, which is tenfold higher than results for literature-reported membranes, a H-2/CO2 selectivity of 20.9, and a H-2/CH4 selectivity of 17.3. The approach presented offers an alternative pathway for the preparation of thin zeolite membranes with superior permeability and selectivity in gas separation applications.