A review of the development of porous substrate-supported carbon membranes

Carbon membranes have attracted extensive attention because of their outstanding performance and excellent stability in the separation of gases, particularly of those with molecular sizes close to that of the membrane pores. However, they suffer from problems such as difficulty in fabrication, low permeability and poor physical strength, which greatly limit their industrial applications. These problems may be solved by supporting the thin carbon membrane on a porous substrate, forming a composite carbon membrane. The properties of the substrate play a key role, especially in the surface properties. A low surface roughness, high porosity, small pore size and fewer defects of the supporting substrate significantly favor membrane fabrication and performance. It is important to develop an effective and low cost surface modification of porous substrates to meet the requirements of membrane fabrication to optimize the selective permeability and economicsof the composite carbon membranes. Research progress on the substrate materials, such as material selection, pore size distribution and surface modification, as well asmembrane fabrication including precursor selection, coating, carbonization and post-treatment are summarized.