High performance ZIF-8 molecular sieve membrane on hollow ceramic fiber via crystallizing-rubbing seed deposition

In this report, a continuous well-intergrown ZIF-8 membrane on hollow ceramic fiber tube was successfully synthesized by a novel crystallizing-rubbing seed deposition. It is shown that the obtained ZIF-8 membrane was compact and defect-free, with a thickness of about 5 mu m. The obtained membrane displayed high H-2 molecular sieve separation performance. Specifically, the H2 permeance reached an excellent value of 1.1 x 10(-6) mol m(-2) s(-1) Pa-1, and the ideal separation factors for H-2/CO2, H-2/N-2 and H-2/CH4 were calculated to be 5.2, 7.3 and 6.8 at room temperature, respectively. We show that the fine seeds generated by crystallizing-rubbing play the key role for enhancing the heterogeneous nucleation of ZIF-8 crystals, which thus result in a high quality ZIF-8 membrane. (C) 2013 Elsevier B.V. All rights reserved.