CO_2分离中空纤维复合膜的制备及其气体渗透性能的研究

以甲基丙烯酸二甲基氨基乙酯(DMAEMA)-聚乙二醇单甲醚甲基丙烯酸酯(PEGMEMA)共聚物为分离层材料,以聚砜(PSf)中空纤维膜作为底膜,采用浸渍涂层的方法制备了P(DMAEMA-PEGMEMA)/PSf中空纤维复合膜。考察了涂层液中共聚物的含量和涂层次数对中空纤维复合膜的性能以及操作条件(温度和压差)对分离性能的影响。实验结果表明,涂层液中共聚物的质量分数为2%、经4次涂层制备的中空纤维复合膜具有较佳的性能,在35℃,0.2MPa条件下CO2渗透速率达24.3GPU,选择性系数αCO2/N2,αCO2/CH4,αCO2/H2分别为30.9,12.5,1.5;在中空纤维复合膜中CO2,N2,CH4,H2的渗透速率符合Arrhenius关系式;N2,CH4,H2在中空纤维复合膜中的渗透行为符合溶解-扩散模型,CO2的渗透由溶解-扩散和促进传递两部分组成。

Preparation of Hollow Fiber Composite Membrane for CO2 Separation and Its Gas Permeation Properties

DMAEMA-PEGMEMA copolymer was synthesized from poly(ethylene glycol methyl ether methacrylic ester)(PEGMEMA) and dimethylamino ethyl methacrylate(DMAEMA).Hollow fiber composite membrane was prepared through coating the DMAEMA-PEGMEMA copolymer as separating layer onto polysulfone hollow fiber membrane as supporting layer.The effects of coating conditions including coating solution concentration and sequential coating times on performance of the hollow fiber composite membrane were investigated.Influences of operating conditions including temperature and trans-membrane pressure on permeation properties of the composite membrane were studied.The optimal preparation conditions for the composite membrane were mass fraction of the copolymer in coating solution 2% and sequential coating 4 times.Under the conditions of 35 ℃ and(0.2 MPa,) permeation rate of CO_2 through the composite membrane was 24.3 GPU,and its selectivity coefficients to CO_2/N_2,CO_2/CH_4 and CO_2/H_2 were 30.9,12.5 and 1.5,respectively.The permeations of CO_2,N_2,CH_4 and H_2 through the composite membrane obeyed Arrhenius equation.The permeation of N_2,CH_4 and H_2 through the composite membrane followed dissolution-diffusion mechanism,and both the dissolution-diffusion and the facilitated transport contributed to CO_2 permeation through the composite membrane.