Preparation of Polyimide/Ionic Liquid Hybrid Membrane for CO₂/CH₄ Separation

Area of Science:

• Materials Science
• Chemical Engineering
• Environmental Science

Background:

• Carbon dioxide (CO2) separation and recovery remain challenging industrial processes.
• Ionic liquids (ILs) show promise for CO2 capture due to their affinity and solubility.
• Polyimide (PI) membranes are widely used but require enhancement for efficient CO2 separation.

Purpose of the Study:

• To develop advanced polyimide membranes for improved CO2 separation.
• To investigate the effect of incorporating various imidazole ionic liquids into a polyimide matrix.
• To evaluate the gas separation performance and mechanical properties of the resulting composite membranes.

Main Methods:

• Preparation of polyimide membranes blended with four different imidazole ionic liquids (IL1-IL4) using a high-speed mixer.
• Characterization of the mechanical properties of the prepared membranes.
• Measurement of gas separation permeability (CO2/CH4) for the composite membranes.

Main Results:

• The PI/IL3 membrane exhibited a CO2/CH4 selectivity of 180.55, a 2.5-fold increase compared to the neat PI membrane.
• CO2 permeability for the PI/IL3 membrane reached 16.25 Barrer, surpassing the 2008 Robeson upper bound.
• The PI/IL3 membrane demonstrated superior gas separation performance compared to other formulations in this study.

Conclusions:

• Imidazole ionic liquid modification significantly enhances the CO2/CH4 separation performance of polyimide membranes.
• The PI/IL3 composite membrane represents a highly effective material for CO2 capture applications.
• This approach offers a viable strategy for overcoming limitations in current CO2 separation technologies.