Solid-polymer mixed matrix membranes for gas separation: polyimide and inorganic solid materials

Abstract

Mixed matrix membranes have presented an interesting approach to improve both selectivity and permeability which are the basic separation properties of the membrane. In this study, MMMs were fabricated to investigate the formation and the gas separation performance using three different inorganic fillers as the dispersed phase in Matrimid 5218 polymer matrix for CO₂/CH₄ separation. Matrimid dense membrane and MMMs incorporating activated carbon, γ-AI₂O₃ and 4A zeolite for gas separation were successfully fabricated using solution-casting method in UOP lab. Single gas permeation measurements were carried out to measure permeabilities by a time-lag method at 50 °c and an upstream pressure of 100 psig. The obtained results showed that the incorporation of inorganic fillers into Matrimid polymer resulted in increasing permeability and decreasing selectivity as the increasing inorganic loading. Nevertheless, 15 wt.% activated carbon loading showed the improved CO₂ separation performance of activated carbon-Matrimid MMMs by which both CO₂ permeability and CO₂/CH₄ selectivity increased significantly compared to those of pure Matrimid membrane. The alteration of fabrication method in PPC lab was made use of incorporating γ-AI₂O₃ into Matrimid polymer in order to improve the CO₂/CH₄ separation properties. Single gas permeation measurements of the tested gases were also carried out at room temperature and 10 0 psi using a different set up of membrane testing unit. γ-AI₂O₃-Matrimid MMMs were effectively fabricated in PPC lab, resulting in an increase of gas permeances in combination with an increase in CO₂/CH₄ selectivity at a higher γ-AI₂O₃ loading.