羧基化聚酰亚胺膜的制备及其对CO2/CH4分离性能的研究

Preparation of carboxylated polyimide membrane and its performance in separation of CO_2/CH_4

通过羟基聚酰亚胺(HPI)与对氟苯甲酸间的亲核取代反应合成了羧基化聚酰亚胺(CPI),以水为绿色溶剂,采用溶剂挥发法制备了不同羧化度的CPI膜,研究了引入羧基对CPI膜的CO_2、CH_4渗透分离性能的影响。结果表明,随着羧化度的增加,CPI膜的CO_2渗透系数以及CO_2/CH_4的选择性均不断增加,制备的CPI膜打破了trade-off规则。当羧化度为19%、压力为0.1 MPa、温度为25℃时,CO_2的渗透系数为68 Barrer,CO_2/CH_4的选择性达到78,CPI膜比纯HPI膜的CO_2渗透系数和CO_2/CH_4选择性分别提高了467%和224%。

Carboxylated polyimide（CPI） is successfully prepared through nucleophilic substitution reaction between hydroxy polyimide（HPI） and para-fluorobenzoic acid. Furthermore,CPI membranes with different carboxylated degrees are prepared via solvent evaporation method with water as a solvent. The effects of carboxylated degree on CO2 permeability and CO2/CH4 selectivity performance of CPI membranes are studied. It is indicated that both CO2 permeability and CO2/CH4 selectivity of CPI membranes increase obviously with the increase of carboxylated degrees,which breaks the trade-off rule. The CO2 permeability coefficient and the CO2/CH4 selectivity of CPI membranes can reach 68 Barrer and 78 when CPI membranes have a 19 wt% of carboxylated degree,pressure is 0. 1 MPa and temperature is at 25℃.Compared to pure HPI membrane,CO2 permeability coefficient and CO2/CH4 selectivity of CPI membranes increase by 467% and 224%,respectively.