Preparation And Performance Of Polyacrylonitrile Based Asymmetric Carbon Membrane

Carbon membrane is a novel porous carbon-based membrane material with excellent gas separation performance and thermal resistance, which combines the super microporous structure of carbon material with the high efficiency and energy saving advantages of membrane material and shows broad prospect in gas separation. However, it’s still industrially unavailable because of its high cost and low gas permeance flux for thick gas separation layer. Therefore, it’s essential to develop cheap precursors with high performance and optimize the preparation process to prepare low-cost carbon membrane with high permeance flux and accelerate its industrial application.In this paper, the asymmetric carbon membrane (ACM) was prepared by dry-wet phase inversion method, preoxidation and carbonization process, in which low-cost polyacrylotrile was used as precursor. The effect of preparation parameters of phase inversion, preoxidation and carbonization process on the morphology and gas separation performance of obtained ACM was investigated by constant pressure variable volume method, SEM, XRD, FT-IR and so on. Results were as follows:(1) The phase inversion process had a great effect on the morphology and gas separation performance of ACM. Reducing the concentration of casting solution could improve the gas permeability of ACM, but impair its selectivity and mechanical performance. The ACM prepared by different solvents and additives exhibited different pore structure and gas separation performance. The ACM prepard by N-methyl pyrrolidone (NMP) had good permeability and mechanical performance. With the increase of polyethylene glycol (PEG) concentration, polyvinyl pyrrolidone (PVP) concentration and the molecular weight of PEG, the obtained ACM showed denser structure and better mechanical performance, but low permeability.(2) The preoxidation process had a great influence on the morphology and gas separation performance of ACM. Increasing the preoxidation temperature, retention time and air flow rate were all beneficial to improve the permeability. However, the excessive preoxidation would make the performance decrease.(3) The carbonization process had a great impact on the morphology and gas separation performance of ACM. The permeability of ACM increased with the enhancement of carbonization temperature. The permeability of ACM increased initially and then decreased as the extension of carbonization retention time, reaching the maxium at the time of one hour.