High-performance ZIF-8/biopolymer chitosan mixed-matrix pervaporation membrane for methanol/dimethyl carbonate separation

The separation of dimethyl carbonate (DMC) –an ecofriendly organic compound– from a reaction medium is oftentimes complicated due to the presence of other organic compounds, particularly when the mixture forms an azeotrope. To this end, pervaporation is proposed in this work as the perfect candidate to solve this separation puzzle, using novel membranes which flipped the ratio of the binary mixture methanol (MeOH) and DMC (from 10:90 to ∼90:10). ZIF-8 fillers were incorporated into chitosan (CS) biopolymer matrix to prepare these mixed-matrix membranes (MMM). At 15 wt% loading of ZIF-8/CS, the～30 μm-thick MMM showed an exceptional selectivity of 11.2, with MeOH permeance of 97.7 GPU at 50 ℃. This superior separation performance is attributed to the higher MeOH affinity to the CS matrix, further reinforced with the preferential channels of ZIF-8 fillers for MeOH. This successful separation of binary organic mixtures elevates a crucial part of downstream processing, merely achieved with conventional distillation, and most importantly, open doors to greener fuels.