A Review on the Progress in Nanoparticle/C Hybrid CMS Membranes for Gas Separation

Carbon molecular sieve (CMS) membranes are novel materials derived from the pyrolysis of the polymeric precursors and have a well-developed ultra-microporous structure that can separate small gas pairs with minor difference in diameter, and thus exhibit higher gas permeability and selectivity than polymeric membranes. However, the gas permeability for traditional pure CMS membranes now cannot satisfy the requirements of commercial applications due to their disordered pore structure and high gas molecular diffusion resistance. Incorporating functional materials into membrane precursors to fabricate hybrid CMS membranes has been regarded as an effective way to tune the disordered pore structure of traditional pure CMS membranes, and thus to greatly improve their gas permeability. Many nanoparticles have been tested as the functional foreign materials to fabricate the hybrid CMS membranes with more developed microporous structure and enhanced gas separation performance. This review discusses the hybridized nanoparticle selection and effect of the species, quantities and particle sizes of the foreign materials on CMS membrane characteristics and performance. The function of the materials incorporated inside the hybrid CMS membranes is also analyzed. It is identified that preparation of hybrid CMS membranes provides a simple and convenient route to efficiently improve the trade-off relationship between permeability and selectivity, and to enable the construction of carbon-based composite materials with novel functionalities in membrane science.