ZIF-8 micromembranes for gas separation prepared on laser-perforated brass supports†
Abstract
ZIF-8 is an imidazolate-based metal–organic framework (MOF). ZIF-8 micromembranes of 20–32 μm diameter are prepared by synthesizing the MOF on Nd:YAG laser-perforated 75 μm thick brass sheets (63/37 Cu/Zn). The laser irradiation activates the brass support, promoting ZIF-8 growth. A thick and continuous ZIF-8 membrane is crystallized on the laser irradiation outlet side of the support, while the inlet side and the inner surface of the microperforations are also coated with ZIF-8 intergrowth crystals. Laser perforated brass supports are not only cheap, flexible, strong, and easy to handle and to process as membrane materials; they are also chemically compatible with the ZIF-8 composition because of the shared Zn element. The ZIF-8 membranes obtained are characterized by XRD, SEM, EDX, TGA and N2 sorption analysis. Furthermore, the membranes are applied to the separation of equimolar H2–CH4, He–CH4, CO2–CH4 and O2–N2 mixtures confirming the expected molecular sieving effect due to the MOF microporosity.