ZIF-67 membranes supported on porous ZnO hollow fibers for hydrogen separation from gas mixtures

Co-based zeolitic imidazolate framework-67 (ZIF) membranes present impressive potential to be applied for efficient gas separation. However, the synthesis of ZIF-67 membrane is challenging because ZIF-67 crystals tend to nucleate and grow in the reaction solution rather than on the substrate surface. In this work, ZIF-67 membranes were developed on porous ZnO hollow fibers via in situ solvothermal growth method. The effects of different ZnO supports, surface activation, growth duration, and growing temperatures on the resultant membrane performance were carefully investigated. The optimized ZIF-67 composite hollow fiber membrane displayed desirable permeation performance, ideal selectivities for single gas, and separation factors for gas mixtures. The achieved H-2 permeance was 8.98 x 10(-8) mol m(-2) s(-1).Pa-1 and ideal selectivities for H-2 gas pairs with CO2, N-2, and CH4 were 5.14, 11.75, and 15.89, respectively, which compared favorably with other reports in the literature. The developed ZIF-67 membrane exhibited good stability in terms of gas permeances between 30 and 200 degrees C. Furthermore, the membrane showed almost constant H-2 permeance and H-2/CH4 separation factor during the 50-h run at 150 degrees C, demonstrating the excellent thermal stability of membrane. The fabrication of the excellent ZIF-67 membrane can be achieved just in one cycle of growth with high reproducibility.

Automated summary

In this study, Co-based zeolitic imidazolate framework-67 (ZIF) membranes were successfully developed on porous ZnO hollow fibers using an in situ solvothermal growth method. The resulting membranes exhibited desirable permeation performance, ideal selectivities for single gas, and separation factors for gas mixtures. The membranes also displayed good stability in terms of gas permeances and showed excellent thermal stability. The development of these membranes provides important insights for the advancement of efficient gas separation technologies.