Enhanced ethylene/ethane selectivity of PI membrane with functionalized zeolite addition

초록

Mixed-matrix membranes (MMMs), consisting of fillers dispersed in a polymer matrix, have been extensively studied for gas separation. However, their application in ethylene/ethane (C2H4/C2H6) separation remains limited. This study examines the impact of incorporating highly selective zeolite fillers into a 6FDA-DAM-type polyimide on C2H4/C2H6 separation performance. We selected 4-methoxybenzene-functionalized MOR (f-MOR) as the filler due to its exceptional C2H4/C2H6 adsorptive selectivity. Adding 20 wt% f-MOR increased C2H4 permeability by 63% and enhanced C2H4/C2H6 ideal selectivity by 11%, reaching 22.7 Barrer and 5.2, respectively, compared to the neat polymer membrane (13.9 Barrer, ideal selectivity of 4.7). In contrast, incorporating 20 wt% neat MOR increased C2H4 permeability to 34.7 Barrer but reduced ideal selectivity to 3.1. The enhanced selectivity of MMMs is attributed to the increased solubility difference of ethylene by the addition of f-MOR, while diffusion selectivity is not improved by the filler. Under a binary mixed-feed gas, the MMM with 20 wt% f-MOR exhibited a drop in selectivity (2.5), indicating low-pressure plasticization-like behavior. While this is the first report to show the enhanced C2 hydrocarbon gas separation performance with zeolite addition, these findings highlight the need for strategies that integrate adsorbent and membrane functionalities to achieve high-performance C2H4/C2H6 separation.

키워드