# Progress, Challenges, and Opportunities in Ionic Liquid–Modified Polymer Membranes for CO2 Separation

## TL;DR

This review explores how ionic liquid-modified polymer membranes can improve CO2 separation and conversion, addressing challenges like selectivity and stability.

## Contribution

The paper provides a comprehensive review of recent advances and challenges in using ionic liquids in polymer membranes for CO2 capture and conversion.

## Key findings

- Ionic liquids enhance CO2 solubility and membrane performance.
- IL-functionalized membranes face challenges like leaching and thermal limitations.
- Integrated systems for CO2 capture and catalytic conversion are emerging.

## Abstract

Driven by the critical challenge of mitigating anthropogenic
CO2 emissions, the field of carbon capture and utilization
(CCU)
has undergone rapid development. Among these, membrane-based CO2 separation stands out for its energy efficiency and ease
of industrial implementation. However, challenges such as the selectivity-permeability
trade-off and plasticization limit its effectiveness. Functionalizing
membranes with ionic liquids (ILs) has emerged as a promising strategy
that takes advantage of the ILs’ high CO2 solubility,
stability, and tunability to enhance separation performance. Beyond
CO2 capture, ILs also serve as key promoters in CO2 conversion by facilitating various reactions. This Review
summarizes recent progress in IL-functionalized polymer membranes,
highlighting advances in polymerized ILs, mixed matrix membranes,
and hollow fiber configurations. Representative studies are discussed
to illustrate how IL incorporation can improve gas transport, selectivity,
and stability and enable integrated systems for simultaneous CO2 capture and catalytic transformation. Remaining technical
challenges, including IL leaching, polymer compatibility, and thermal
constraints, are identified, providing guidance for future design
and optimization of next-generation IL-membrane platforms for CO2 separation and conversion.