Enhancing plasticization-resistance of mixed-matrix membranes with exceptionally high CO2/CH4 selectivity through incorporating ZSM-25 zeolite

Abstract Partially Li + exchanged Na-ZSM-25 zeolites (LNZ25) were incorporated into the commercial polymer Matrimid ® 5218 to yield a mixed-matrix membrane (MMM) via solvent-casting. ZSM-25 has exclusive admission of CO 2 and complete exclusion of CH 4 and is therefore an ideal candidate for MMMs. The fillers were evenly dispersed in the polymer matrix with good adhesion. The separation performance of the fabricated MMMs with 0–15 wt% filler loadings are determined by both single and binary gas permeability using a constant pressure variable volume apparatus. Single gas permeation tests on the MMM with 5 wt% filler loading show exceptionally high CO 2 /CH 4 selectivity (169 at 5 bar) and a plasticization-resistance-like behaviour, i.e. the selectivity increases as the feed pressure increases. Binary gas measurements indicate the CO 2 /CH 4 selectivity of the MMM is constant with an increase of pressure while the selectivity of the pristine Matrimid decreases with increased pressure. The exclusive admission of CO 2 and the rejection of CH 4 of the LNZ25 contributes to enhanced permeability and plasticization-resistance-like performance of the MMM.