Membranes with hollow bowl-shaped window for CO2 removal from natural gas

Abstract

Mixed matrix membranes (MMMs) are crucial for CO₂ separation and offer a potential solution to overcome conventional gas separation. Nevertheless, MMMs face challenges due to interfacial defects in membranes, which results in poor gas separation performance. In this study, γ-cyclodextrin (γ-CD) based MMMs were synthesized via a simple solution casting method. γ-CD could be molecularly dispersed in Matrimid matrix up to 3 ​wt% loading without defects at the interfaces in membranes. ATR-FTIR results showed that γ-CD based MMMs have significant peak with loading increases. Leveraging the high CO₂ solubility and high porosity of γ-CD, Matrimid/γ-CD based membranes exhibit improved CO₂/CH₄ selectivity. Especially, the CO₂ permeability of Matrimid-3%-CD membrane increased by 40 % (from 13.35 to 18.71 Barrer) and CO₂/CH₄ increased by 99 ​% (from 36.08 to 71.96), respectively compared to pristine Matrimid membrane. This demonstrates that the incorporation of γ-CD in Matrimid membrane significantly improves both permeability and selectivity. The Matrimid-γ-CD membrane also demonstrated superior long-term operation stability after aging 593 days. Thus, this study lays the foundation for the development of γ-CD-based membranes with high CO₂/CH₄ selectivity, providing potential pathways for CO₂ separation processes in CO₂/CH₄ separation.