An ensemble synthesis strategy for fabrication of hollow fiber T-type zeolite membrane modules

T-type zeolite membranes were prepared on four-channel α-Al₂O₃ hollow fibers by secondary growth method with an ensemble synthesis strategy. Prior to the membrane synthesis, a bundle of α-Al₂O₃ hollow fibers were assembled on the ceramic bases by enamel sealing. The membrane modules with membrane areas of 0.03 m² and 0.54 m² were then seeded with ball-milled T-type zeolite crystals by dip-coating. A uniform and continuous T-type zeolite seed layer was obtained for a seed concentration of 1.5 wt% and a coating time of 15 s. The seeded modules were then immersed in synthesis solution for ensemble hydrothermal crystallization. After optimizing the synthesis parameters, high-quality hollow fiber zeolite membrane modules could be prepared with good reproducibility. The membrane module with 0.03 m² exhibited a water permeation flux of 2.25 kg m⁻² h⁻¹ and a separation factor of 1348 for PV dehydration of 90 wt% ethanol/water mixture at 348 K. The membrane modules had long-term stability in acidic solution (pH~3) for 450 h as well. A pilot-scale apparatus composed of two 0.54 m² membrane modules connected in series was further constructed for PV dehydration of 90 wt% isopropanol/water. The ensemble synthesis strategy paves a way for the industrialization of hollow fiber T-type zeolite membranes.