The Preparation And Structure Properties Of Carbon Membranes Derived From Poly(Furfuryl Alcohol) For Gas Separation

Carbon membranes prepared by carbonization of carbonaceous materials, as novelporous inorganic membranes, have been widely applied in many industrial fields due to theirhigh mechanical strength, thermal and chemical stability in non-oxidizing atmosphere.However, most of precursors for preparing carbon membrane are commercially expensive,which may greatly limit the commercial competition with organic membranes. It is necessaryto find out a low cost precursor to prepare carbon membranes. Poly (furfuryl alcohol)(PFA)has several advantages as the precursor for preparing the carbon membranes such as low costand high residual carbon. Unfortunately, the PFA used to prepare the carbon membranes hasthe high viscosity and polymerization degree which make the preparing procedure morecomplex by repeatly coating with dilute solution. Therefore, it is necessary to look for a newway to obtain a liquid PFA to simplify the preparing procedure.Liquid PFA as precursor was synthesized with different catalysts (oxalic acid and iodine)to prepare tubular C/CMS composite membranes in the thesis. Effect of carbonizationtemperature and the thermal soak time and test conditions were investigated. TG, FTIR,XRD and SEM were employed to characterize the PFA microstructure and the gas separationperformance of carbon membranes.The results show that the PFA synthesized by oxalic acid and iodine are transformed toturbostratic carbon structure from cross-linking polymeric structure by a series of reactionssuch as cyclization and aromatization during pyrolysis. Although they followed similarpyrolysis behavior, the chemical reaction and the resultant microstructure of carbonmembranes are different. Molecular structures of PFA have effect on the microstructure andgas separation performance of carbon membranes. Especially, the PFA catalyzed by oxalichad high thermal stability owing to its high cross-link degree. The resulting composite carbonmembranes showed superior permselectivity for gas pairs such as H₂/N₂, CO₂/N₂, O₂/N₂ andCO₂/CH₄, and the highest permselectivity were 469.09, 60.55, 13.09 and 158.57 at 25℃,respectively.