Vacuum resistance treated ZIF-8 mixed matrix membrane for effective CH4/N2 separation

Abstract

CH4/N2 separation, a viable way to purify energy gas and reduce the greenhouse effect, requires the use of highly gas permeable membrane, but acid environment affects the membrane stability. In this work, the ZIF-8@VR nanoparticle was synthesized via a high vacuum resistance sintering method (VRSM), which increased the acid resistance to pH2.8 because of surface carbonization and stiffening. The structure of the ZIF-8@VR nanoparticle was investigated by XRD, SEM, FTIR, BET and Raman analysis, followed by blending it with polyacrylic acid (PAA) to fabricate PAA/ZIF-8@VR mixed matrix membranes (MMMs). The MMMs exhibited excellent CH4 permeance and satisfactory CH4/N2 selectivity, with the optimal CH4 permeance (~1763 GPU) for the MMM with 66.8 wt% ZIF-8@VR filler. Furthermore, compared with pure PAA membrane, the MMMs with ZIF-8@VR filler could improve the CH4/N2 selectivity from 1.3 to 3.1.