Membranes with hollow bowl-shaped window for CO2 removal from natural gas
Weiwang Lim, He Wen, Ji Ma, Shabi Ul Hassan, Jingcheng Du, Qian Sun, Dong Cao, Jian Guan, Hongjun Zhang, Jiangtao Liu
Abstract
Mixed matrix membranes (MMMs) are crucial for CO 2 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 CO 2 solubility and high porosity of γ-CD, Matrimid/γ-CD based membranes exhibit improved CO 2 /CH 4 selectivity. Especially, the CO 2 permeability of Matrimid-3%-CD membrane increased by 40 % (from 13.35 to 18.71 Barrer) and CO 2 /CH 4 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 CO 2 /CH 4 selectivity, providing potential pathways for CO 2 separation processes in CO 2 /CH 4 separation. Gamma-cyclodextrin (γ-CD) with unique 3D hollow-bowl inner cavity was designed to enhance CO 2 /CH 4 separation performance for natural gas purification.