Highly permeable ZIF-8 membranes for propylene permselective pervaporation under high pressure up to 20 bar

ZIF-8 membrane has been deemed as the most promising contender for addressing the chemical industry's energy-intensive C3H6/C3H8 separation process. However, to the best of our knowledge, there are no reports available to access the realistic separation performance of the ZIF-8 membrane under industrial conditions. In this work, we systematically studied the pervaporation performance of ZIF-8 membranes for liquid C3H6/C3H8 mixture. First, we refine the dip-coating and thermal conversion (DCTC) method to achieve highly permeable ZIF-8 membranes. The C3H6 permeances of the resultant ZIF-8 membranes can be controlled in the range from 6.5 × 10−9 to 9.3 × 10−8 mol m−2 s−1 Pa−1 with C3H6/C3H8 separation factor consistently higher than 100. Then, the ZIF-8 membrane was employed for the pervaporation separation of equimolar C3H6/C3H8 mixture at 50 °C and 20 bar, achieving C3H6 flux up to 0.93 kg m−2 h−1 along with a separation factor of 19. Furthermore, we explore the performance of the ZIF-8 membrane for a liquid C3H6/C3H8 mixture (70:30), which is a similar composition to that produced from the upstream depropanizer. Consequently, the resultant ZIF-8 membrane exhibits excellent pervaporation stability with a separation factor of 13 and C3H6 flux of 1.1 kg m−2 h−1, demonstrating the great prospect of ZIF-8 membrane in energy-intensive C3H6/C3H8 separation.