Regulating the microporous structure by cavity-shaped molecular sieving channels.

Abstract

Membrane separation technology represents a promising and effective alternative to traditional energy-intensive gas separation technologies. However, most commercial membranes have low permeability and moderate selectivity, which limits their ability to meet the stringent gas purity requirements for hydrogen purification and natural gas upgrading. In this study, Matrimid, a widely used commercial polymer, was selected as the matrix material. Cucurbituril (CB) with selective cavity was incorporated into Matrimid as short-path gas transport channels. This modification increased the gas transport pathways and enhanced the connectivity of gas transmission networks within the membrane structure. The H₂ permeability of Matrimid-CB-5% membrane decreased from 113 to 74 Barrer, while the H₂/CH₄ selectivity increased from 169 to 743 during 600-day aging. Notably, the membranes achieved separation efficiencies that surpassed the latest upper bound line for CO₂/N₂ and CO₂/CH₄ separations. These results indicate a substantial improvement over widely used commercial materials such as Matrimid, cellulose acetate, polysulfone, and other mixed matrix membranes.