Synthesis of high-performance Co-based ZIF-67 membrane for H2 separation by using cobalt ions chelated PIM-1 as interface layer

So far, the reports of ZIF-67 membranes with high permselectivity are rather scarce because ZIF-67 prefers to homogeneous nucleation and growth in the reaction solution rather than heterogeneous nucleation and growth on the substrates. Inspired by the fact that homologous metal ions is helpful to be acted as nucleation centers to promote the preparation of continuous MOF membranes, in this work, we develop a novel and effective synthesis method for in-situ growth of compact ZIF-67 membranes by using Co2+ ions chelated PIM-1 (PIM = polymer of intrinsic microporosity) as interface layer between the ZIF-67 membrane and the alpha-Al2O3 support. After solvothermal synthesis for 48 hat 120 degrees C, a well-intergrown ZIF-67 membrane with a thickness of about 12 mu m can be formed on the Co 7+ @cPIM-1 modified alpha-Al(2)O(3 )disk. For single gas permeation at 25 degrees C and 1 bar, the ZIF-67 membrane shows a high H-2 permeance of 6.2 x 10(-7) mol m(-2) s(-1).Pa-1, with H-2/CO2, H-2/CH4 and H-2/C3H8 ideal separation factors of 15.1, 51.7 and 56.4, respectively. Further, other compact and H-2 permselective ZIF membranes, such as ZIF-7 and ZIF-8 membranes, can be consistently prepared on the Zn2+@cPIM-1 modified substrates by using the same strategy.

Automated summary

A novel and effective synthesis method for in-situ growth of compact ZIF-67 membranes has been developed using Co2+ ions chelated PIM-1 as an interface layer between the membrane and support. The ZIF-67 membrane showed high H-2 permeance and ideal separation factors for various gas mixtures. Additionally, other compact and H-2 permselective ZIF membranes, such as ZIF-7 and ZIF-8 membranes, can be consistently prepared using the same strategy.