Sustainable Fabrication of the Zeolitic Imidazolate Framework-67 Membrane via Supercritical Fluid Processing of the Co-Based Gel Layer

Despite showing great potential in membrane-based gas separation, sustainable fabrication of the high-performance zeolitic imidazolate framework-67 (ZIF-67) membrane remains very challenging. In this study, a supercritical fluid-based protocol was employed for the sustainable synthesis of the ZIF-67 membrane through combining with spin-coating-assisted deposition of a Co-based gel layer. Compared with conventional solution-based protocols, the use of supercritical CO2 as the reaction medium warranted a one-step conversion of the Co-based gel layer into a well-intergrown ZIF-67 membrane under mild reaction conditions; moreover, after evacuating the chamber, unreacted reagents could be fully recovered and repeatedly utilized in ZIF-67 membrane synthesis so that zero pollutant discharge could be realized. The prepared ZIF-67 membrane displayed a H2 permeance of 2.63 × 10–7 mol·m–2·s–1·Pa–1 and an ideal H2/CO2 selectivity of 11.4.