Mixed matrix membrane based on DOCDA polyimide with twisted kink structure and zeolite 4A for energy-efficient oxygen purification

Abstract

Membrane technology has advanced, offering high-quality polymeric membranes with great potential for commercial use. However, producing these advanced membranes is usually costly and involves complex manufacturing. To tackle this issue, a cost-effective alternative has emerged in the form of polyimide (PI) membranes, particularly those derived from DOCDA-ODA, a low-cost organic compound. However, the initial gas permeance of DOCDA-ODA membranes is lower than those of commercial PI membranes such as Matrimid® 5218 and 6FDA-DAM membranes. To address this limitation, this study was aimed at fabricating mixed matrix membranes (MMMs) by incorporating zeolite 4A into the DOCDA-ODA matrix. The MMMs demonstrate promising O2/N2 separation performance, surpassing that of Matrimid® 5218-based membranes. Furthermore, they exhibit an O2/N2 selectivity of 14.8 with an O2 permeability of 2.3 Barrer, surpassing recent benchmarks established by the Robeson upper bounds for polymeric membranes. This exceptional O2/N2 separation performance can be attributed to favorable interfacial interactions between the polymer chains and LTA crystals. Molecular dynamics simulations clarify the role of electronegative atoms, especially oxygen, within the kinked structure of DOCDA-ODA. Thus, DOCDA-ODA-based MMMs hold potential for O2 purification applications, reducing energy consumption by an impressive 49.3% compared to equivalent commercial membrane processes. © 2023 The Korean Society of Industrial and Engineering Chemistry