聚乙二醇导向多级孔ZSM-5分子筛膜的制备及表征

Preparation and characterization of hierarchical ZSM-5 zeolite membranes directed by polyethylene glycol

采用二次生长法,以四通道α-Al_2O_3中空纤维为支撑体,制备多级孔ZSM-5分子筛膜,研究制膜液硅铝摩尔比(n(SiO_2)/n(Al_2O_3))、合成温度、合成时间以及聚乙二醇(PEG)结构导向剂的添加对分子筛膜成膜的影响。结果表明:在硅铝摩尔比为160、合成温度为180℃、合成时间为20 h的条件下,可获得结晶度较高的ZSM-5分子筛膜;引入的PEG分子在晶化过程中包裹在晶体层之间,去模板后产生介孔孔隙;膜层平均孔径随着PEG加入量的增加而变大,在PEG添加量为0. 25%时,纯水渗透通量达到20 kg/(m^2·h·MPa),截留分子量为161 100,对应平均孔径为16. 40 nm,达到了超滤的标准。

Hierarchical ZSM-5 zeolite membranes were synthesized on four-channel hollow fibers through secondary growth method.The effects of n(SiO2)/n(Al2O3),synthesis temperature,synthesis time and the addition amount of polyethyleneglycol(PEG)on the formation of zeolite membranes were investigated.ZSM-5 zeolite membrane with high crystallinity could be achieved at n(SiO2)/n(Al2O3)of 160,synthesis temperature of 180℃and synthesis time of 20 h.The added PEG molecules were encapsulated in zeolite layer during crystallization process,and mesopores were formed by the removal of PEG.In addition,the average pore size of the zeolite membranes increased with increasing PEG addition.In the case of adding 0.25%PEG,the obtained zeolite membrane exhibited a high water permeability of 20 kg/(m^2·h·MPa),and a molecular weight cut-off of 161 100,corresponding to the average pore size of 16.40 nm,and meeting the need of ultrafiltration.