聚酰亚胺/SiO_2杂化膜的制备、表征和气体渗透性能

Preparation,Characterization,and Gas Separation Properties of Polyimide/SiO_2 Hybrid Membranes

采用溶胶凝胶法,在以TiO2为过渡层的硅藻土-莫来石陶瓷膜管基底上,制备了组分不同的聚酰亚胺/SiO2杂化膜。聚酰亚胺是利用4,4′-六氟亚异丙基邻苯二甲酸酐、2,4,6-三甲基-1,3-苯二胺和3,5-二氨基苯甲酸在溶液中进行亚胺化完成的。采用FT-IR、TG/DTA、DSC、SEM、BET和气体渗透测定对膜进行了表征和测试。结果表明,聚酰亚胺通过支链上的羧酸基和SiO2相键连织构成了具有规则孔道的空间网状结构,并且随着SiO2含量的增加孔径逐渐减小;杂化膜具有较高的热稳定性和有机无机兼容性;相对于聚酰亚胺膜,杂化膜对H2、CO2和H2O与N2相比较具有较高的分离性,SiO2含量为25(wt)%的杂化膜对H2/N2、CO2/N2和H2O/N2的分离因子分别达到55.9、31.1和42.8。

In this study, a series of polyimide/SiO2 hybrid membranes supported on TiO2/kieselguhr-mullite were prepared from polyimide with plenty of carboxyl and SiO2 sol via a sol-gel process. The polyimide was solution imidized employing 4,4＇- hexafluoroisopropylidenediphthalic anhydride, 2,4,6- trimethyl- 1,3- phenylenediamine and 3,5- diaminobenzoic acid. Their morphologies, chemical structures, thermal performances, pore distribution and gas permeability were characterized by the methods of SEM, FTIR, TG/DTA, DSC, BET and gas permeability measurement. The results showed that the hybrid membranes possess higher thermal stability and compatibility between the organic and inorganic components. The hybrid membranes possess the space networks with regular pores formed by the connection between the polyimide and SiO2 sol via the carboxyls along the polyimide chain. When compared to the pure polyimide, the hybrid membranes showed higher separation properties for H2, CO2 and H20 relative to N2. The separation factors of the pelyimide/ SiO2 hybrid membranes with 25 （wt）% SiO2 contents for H2/N2, CO2/N2 and H2O/N2 are 55.9, 31.1 and 42.8, respectively.