Carbon Membranes for CO2 Separation

This chapter discusses progress in the design and synthesis of carbon membranes for CO₂ separation. Carbon materials have been used as the fillers for polymeric membranes to fabricate mixed-matrix membranes (MMM), in which the advantages of carbons and polymers are simultaneously attained. Based on the carbon structure, carbon membranes are divided into three categories: graphene membranes with well-defined planar structure, carbon nanotube (CNT) membranes with well-defined cylindrical structure, and carbon molecular sieve (CMS) membranes with amorphous structure. It is difficult to prepare CNT membranes with precisely controlled pore parameters and satisfying CO₂ separation performance, just as is the case for nanoporous graphene membranes. The CO₂ permeability of CMS membranes prepared from mixtures of deacetylated cellulose acetate and polyvinylpyrrolidone is much higher than that of CMS membranes prepared from bare regenerated celluloses. CMS membranes integrated with zeolites, silica oxides, and CNT were successfully fabricated by carbonizing the corresponding MMMs.