Preparation and gas separation properties of Zeolitic imidazolate frameworks-8 (ZIF-8) membranes supported on silicon nitride ceramic hollow fibers

Zeolitic imidazolate frameworks (ZIFs) have attracted great attention due to their potential applications in gas adsorption, catalytic membrane reactors, chemical sensing and gas separation. To achieve the massive industrial application, a number of attempts have been made to prepare supported-ZIF membranes. We successfully synthesized a well-intergrown continuous ZIF-8 membrane on the outer surface of silicon nitride hollow fibers by a one-step hydrothermal method. Through controlling ZIF-8 nucleation and growth rates, the membranes were compact and well-coated. Single gas permeation of H-2, N-2 and CO2 at 25 degrees C, 0.25 MPa indicated the sieving behavior of the obtained membranes. N-2 permeance did not change with permeation time, while H-2 permeance increased in the beginning and keep steady at 8.35 x 10(-7) mol/m(2) Pa s due to the high storage properties of ZIF-8, and CO2 permeance decreased in the first hour, then maintained at 1.15 x 10(-7) mol/m(2) Pa s due to the strong CO2 adsorption in the ZIF-8 and the cooperative interactions of adsorbed CO2 molecules with CO2 passing through. The H-2/CO2 separation factor of 11.67 could be achieved in the separation of 50%H-2/50%CO2 mixture. (C) 2016 Elsevier Ltd and Techna Group S.r.l. All rights reserved.