Functionalization of polymers and nanomaterials for H2/CO2 separation membrane: State-of-the-art, challenges and perspectives

Abstract

Membrane technology provides unique advantages in separating hydrogen from various mixture streams in commercial settings owing to its energy efficiency and small footprints. Conventional polymer membranes have low permeability and selectivity in H₂/CO₂ separation, which limits their commercial application. Mixed matrix membranes (MMMs) which combine the advantages of conventional polymeric materials and inorganic nanomaterials offer tremendous opportunities to surmount the shortcomings and unsatisfactory performances of the polymeric and inorganic counterparts. While delivering attractive features to improve the permeability, selectivity, and durability of the membranes, the insufficient performance improvement of MMMs is closely associated with some bottlenecks, particularly the presence of interface defects caused by poor dispersion and incompatibility with the polymer. Various functionalization strategies have been explored to address these issues. In this review, a comprehensive overview of the functionalization strategies of polymeric membranes and MMMs for hydrogen separation, including their advantages and limitations, the classification of functionalization and the effects of functionalization on performance is presented. The current technical challenges are highlighted and the insights into future research directions are discussed. The progress made in membrane functionalization not only addresses the current limitations but also paves the way for a sustainable and efficient hydrogen economy.