A comprehensive review on zeolite-based mixed matrix membranes for CO₂/CH₄ separation

Area of Science:

• Materials Science
• Chemical Engineering
• Environmental Science

Background:

• Biogas, a renewable fuel, requires carbon dioxide (CO2) and methane (CH4) separation to increase its calorific value and reduce greenhouse gas emissions.
• Zeolite and zeolite-based mixed matrix membranes (MMMs) are promising materials for CO2/CH4 separation due to their inherent thermal and chemical stability.

Approach:

• This review examines the development and performance of zeolite and zeolite-based MMMs for CO2/CH4 separation.
• It highlights modification strategies such as post-treatment, ion-exchange, amino silane-grafting, and ionic liquid encapsulation to enhance membrane performance.
• The review analyzes how these modifications improve interfacial adhesion and reduce defects, leading to higher CO2/CH4 selectivity.

Key Points:

• Zeolite-based MMMs achieve high CO2 permeance (2.0 × 10^-7–7.0 × 10^-6 mol m^-2 s^-1 Pa^-1) and CO2/CH4 selectivity (3–300).
• Ionic liquid and silane modifications show significant improvements in selectivity, reaching up to 90 and 660, respectively.
• These membranes also show potential in water purification and biomedical applications.

Conclusions:

• Zeolite-based MMMs are effective for CO2/CH4 separation, with modifications offering substantial performance gains.
• Further research into advanced modification techniques can unlock new industrial applications for biogas upgrading and beyond.
• This review provides insights into zeolite-based MMMs, encouraging innovation in gas separation technologies.