Poly(vinyl alcohol) mediated bifunctional ZIF-BN nanocomposite for the high-selectivity H2 separation membrane

We combined the advantages of the 2-methylimidazole zinc salt (ZIF-8) and hydroxylated boron nitride (OH-BN) materials to prepare a new bifunctional separation material, namely ZIF-BN. In this, spherical ZIF-8 materials fill the macroporous structure of OH-BN sheets by coordination bonds due to the edge effect. Furthermore, a series of ZIF-BN/PVA membranes were prepared using the vacuum-assisted filtration of the layer-by-layer for the gas separation study. The trace amounts of PVA connect adjacent ZIF-BN sheets through hydrogen bonds, without covering the pore structures of ZIF-8 materials. Based on this exclusive strategy for preparing membranes, the obtained membranes exhibit superior H2 separation performances. Compared with the pure PVA membrane, the H2 permeability, H2/CO2 selectivity, and H2/N2 selectivity of the ZIF-BN/PVA-8 membrane have increased (54, 13, & 12)-fold, to (600 Barrer, 97.2, & 173.6), respectively. This strategy provides a facile way to design new bifunctional membranes for gas separation applications.

Automated summary

We developed a new bifunctional separation material called ZIF-BN by combining the advantages of ZIF-8 and OH-BN materials. The ZIF-8 materials formed a spherical structure by filling the macroporous structure of OH-BN sheets through coordination bonds. Additionally, ZIF-BN/PVA membranes were prepared using a layer-by-layer vacuum-assisted filtration method. The membranes showed significantly improved H2 separation performances compared to pure PVA membranes, with increased H2 permeability, H2/CO2 selectivity, and H2/N2 selectivity.