Advances in CO₂ separation from the landscape of porous aromatic framework-based engineered membranes

Uncontrolled carbon emission contributes significantly towards global warming and climate change necessitating an urgent and effective remedy. CO₂ is one of the major constituents of the greenhouse gas family. The main sources that contribute to CO₂ emission are industries, transports, etc., where CO₂ gets emitted with other gases. Before released into the environment, effective separation of CO₂ from mixture gases can lessen its direct environmental exposure. Traditional techniques for CO₂ separation include adsorption, absorption, cryogenic distillation, and membrane separation. Membrane technology is advantageous in CO₂ separation due to its excellent properties like energy efficiency, affordability, durability, scalability, processing simplicity, and high separation efficiency. Advancements in membrane materials have introduced various advanced materials among which porous aromatic frameworks (PAFs) are proven highly applicable in gas separation. PAFs are a branch of engineered porous materials that offer excellent porosity, substantial surface area, homogeneous pore size, room for structural modification, and anti-aging properties. PAF-based membranes are widely used in various CO₂ separation applications; mostly in natural gas purification and flue gas treatment. This review article has discussed synthetic routes of PAFs, structural modification techniques, membrane applications, and mechanisms in the context of CO₂ separation. The current status of PAF-based membranes is briefly highlighted from an economic and industrial point of view. Future directions for PAF-based membranes such as functionalization or integration of PAFs with other materials/nanomaterials to create hybrid materials with greater CO₂-phillicity are discussed. Moreover, potential aspects to consider in the near future associated with PAF syntheses are also highlighted.