Two-way facilitated transport membrane for CO2 separation with synergy of nucleophilic addition and π-complexing reactions: Molecular simulation and experimental study

Document Type : Research Paper

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Faculty of Engineering, Behbahan Khatam Alanbia University of Technology, Behbahan, Iran

Abstract

Hypothesis: PEBA, also known as polyether-block-amide, has emerged as a highly favorable polymer material for the production of CO2 separator membranes. The membranes made from PEBA rely on the solution-diffusion mechanism for separation. However, the trade-off limitation hinders the enhancement of both permeability and selectivity, posing a crucial challenge in the widespread adoption of these membranes in various industries. To address this issue, incorporating compounds that create facilitate transport mechanism into the separation process proves to be a viable solution.
Methods: To address the trade-off limitation in polymer membranes, a novel two-way facilitated transfer membrane was developed in this research. This membrane consisted of a PEBA matrix with two different carriers. Aniline was selected for its nucleophilic addition reaction towards CO2, while alumina particles served as carriers for π-complexation reactions. The combination of these two carriers within the polymer matrix resulted in the establishment of a two-way facilitated transport mechanism.
Findings: As a result of adding two types of carriers, aniline and alumina, to the PEBA matrix, the permeability of CO2 increased 4.2 times compared to the pure membrane, and the CO2/N2 selectivity also increased 2.1 times compared to the pure membrane, demonstrating the high potential of these two carriers in enhancing separation performance. Molecular simulation results showed that the increase in CO2 permeability was due to the increase in its diffusion coefficient within the membrane thickness, facilitated by the pathways created by alumina and aniline in the polymer matrix. Comparison of the permeability and selectivity of the membrane with other works on the Robeson curve showed that the resulting membrane was able to easily overcome the trade-off limitation, surpass the Robeson boundary, and transform into a membrane suitable for industrial applications in CO2 separation.

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