Abstract

We report a new strategy: use of polymer−zeolite composite hollow fibers as supports. Zeolite membranes with high performance (flux = 8.0−9.0 kg m⁻² h⁻¹, α >10000) can be synthesized directly on polymer−zeolite composite hollow fiber supports by a single in situ hydrothermal crystallization. The zeolite crystals imbedded in the polymer hollow fiber serve as seeds for the zeolite membrane growth, and they also “anchor” the zeolite membrane to the support to increase the adhesion of the zeolite membrane. Therefore, a separate and often complex seeding process can be omitted. A very uniform crystal distribution can be obtained easily, so continuous zeolite membranes can be prepared with high reproducibility. These composite hollow fibers can be produced simply by blending zeolite crystals into the polymer feed before the hollow fiber extrusion and thus are expected to be inexpensive.

We demonstrate for the first time that by one single hydrothermal synthesis a zeolite LTA membrane with a high flux of 9.0 kg/m² h and high water/ethanol separation factor of 10000 could be formed on a ceramic hollow fiber that is known for its ability to form a compact module. The flux is the highest reported in the literatures. A novel seeding method, dipcoating−wiping, is key to obtaining zeolite membranes with high separation performance because it reproducibly produces a uniform and trace seed layer on the support. This new seeding method is expected to have serious implications for making defect-free zeolite films and membranes for many applications. The membranes reported here have the potential to solve the key problems that have prevented zeolite membranes from widespread use for biofuel production.