Ultrathin Low-Crystallinity MOF Membranes Fabricated by Interface Layer Polarization Induction

Abstract

Practical, ultrathin metal-organic framework (MOF) membranes have the potential to achieve otherwise difficult separations, but current fabrication methods still face challenges in the simultaneous improvement of both selectivity and permeance. Here, ultrathin, low-crystallinity-state MOF (LC-MOF) membranes are realized by a facile general method of interface layer polarization induction. This is achieved using an interface layer having metal ions with dense and uniform distribution, resulting in the creation of abundant open metal sites. Three types of LC-MOF membranes (45-150 nm) are fabricated, among which ZIF-8 membranes modified in situ with diethanolamine (DZIF-8) display the best performance for propylene/propane separation, showing unprecedented propylene permeance (2000-3000 Gas Permeance Units) with very high propylene/propane selectivity (90-120).

Keywords: MOF membranes; low-crystallinity MOF; olefin/paraffin separation; propylene/propane separation; ultrathin membranes.