Preparation And Gas Separation Performance Of Asymmetric Carbon Membrane

Carbon membrane is a new type of carbon membrane material, which is made from polymer membrane by carbonization process. With the advantage of high thermal stability and chemical stability, gas permeability and gas selectivity, Carbon membrane has a broad application prospect in the field of gas separation, especially in small molecule gas separation. At present, the preparation of the carbon film is generally homogeneous carbon film, despite its permeability coefficient of gas is higher, but it is difficult to achieve high gas permeation flux. Therefore we are going to overcome the shortage by changing the membrane structure.The asymmetric carbon membranes were prepared by the dry/wet phase inversion methods and then carbonization using PAA as the precursor, DMAc as the solvent and additive. The effects of the preparation technology parameters of phase inversion and carbonization on the structure and gas separation performance of asymmetric carbon membranes were investigated by SEM, XRD and variable volume-constant pressure method.The results showed that (1) the preparation technology parameters of phase inversion has great influence on asymmetric carbon membrane structure and gas separation performance.increasing polymer concentration and evaporation time could make the membrane more denser which conducts a higher gas selectivity and lower gas permibility. changing coagulation medium could also differ the gas separation performance.With more higher PVP contents in the casting solution,the surface layer of asymmetric carbon membrane is more denser,the gas permeability is more lower,but the effect of the PEG contents is on the opposite way (2) In the inspection of carbonization temperature,this paper found that the assymmetric carbon film has obvious asymmetry structure (consists of surface layer and the porous support layer), and its microstructure is disorderly composed of microcrystalline carbon structure.With the raising of the carbonization temperature, the degree of order increase.The resrarch of gas perfoamance showed that the membrane gets the higher gas flux and gas selectivitywith the incaressing of the pyrolysis temperature. Carbonization temperature time can increase the porosity of the asymmetric carbon membrane, improving the oxygen and nitrogen permeability performance of asymmetric carbon membrane.