Sub-Zero Temperature Synthesis of Pressure-Resistant ZIF-8 Membrane with Superior C₃H₆/C₃H₈ Separation Performance

The ZIF-8 membrane holds great promise for high-efficiency C 3 H 6 /C 3 H 8 separation. Its large-scale industrial applications, however, still suffer from permeance-selectivity tradeoff, low reproducibility, and inevitable performance fluctuation under varying operation pressures. In this work, we in situ prepared the high-quality ZIF-8 membrane through combining sub-zero temperature synthesis and twin zinc source. Benefiting from the precisely tuned nucleation and growth kinetics, both the grain boundary structure and thickness of prepared ZIF-8 membrane could be well controlled, resulting in stable C 3 H 6 /C 3 H 8 selectivity approaching 167 irrespective of operation pressure and C 3 H 6 feed fraction with steady C 3 H 6 permeance up to 3.2 × 10 –8 mol m –2 s –1 Pa –1, which ranks the highest among all porous α-Al 2 O 3 -supported ZIF-8 membranes reported in literature. In addition, the above protocol is featured with high reproducibility, which is of vital importance for the scale-up manufacture. Our research provides a promising solution to remaining concerns hindering large-scale production and application of ZIF-8 membranes toward reliable separation of C 3 H 6 /C 3 H 8 gas mixture.