6FDA-TMPDA-DABA/TiO_2杂化膜的制备、表征和气体渗透性能

Preparation,characterization,and gas separation properties of 6FDA-TMPDA-DABA/TiO_2 hybrid membranes

以硅藻土-莫来石陶瓷膜管为支撑体,以TiO2为过渡层,通过溶胶凝胶法利用具有大量支链的聚酰亚胺和TiO2溶胶制备了系列不同TiO2含量的聚酰亚胺/TiO2杂化膜。聚酰亚胺是利用4,4’-六氟亚异丙基-邻苯二甲酸酐(6FDA)、2,4,6-三甲基-1,3-苯二胺(TMPDA)和3,5-二氨基苯甲酸(DABA)在溶液中进行亚胺化完成的。采用FTIR、TG/DTA、DSC、TEM、BET和气体渗透测定对系列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TiO2相键连织构成了具有规则孔道的空间网状结构,并且随着TiO2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相对于N2具有较高的分离性,TiO2含量为25%(质量分数)的杂化膜对H2/N2、CO2/N2和H2O/N2的分离因子分别达到56.6、31.3和55.3。

In this study, a series of polyimide/TiO2 hybrid membranes supported on TiO2/kieselguhr-mullite （K- M） were prepared from polyimide with plenty of carboxyl and TiO2 sol via a sol-gel process. Polyimide was solution imidized employing 4,4 ＇-hexafluoroisopropylidenediphthalic anhydride （6FDA）, 2,4, 6-trimethyl-1,3- phenylenedi-amine （TMPDA） and 3,5-diaminobenzoic acid （DABA）. Their morphologies, chemical structures, thermal performances, pore distribution and gas permeability were characterized by methods of TEM, 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 TiO2 sol via the carboxyls along the polyimide chain. The hybrid membranes showed higher separation properties for H2, CO2, N2 and H2O when compared to the pure polyimide. The separation factors of the polyimide/TiO2 hybrid membranes with 25wt% TiO2 contents for H2/N2, CO2/N2 and H2O/N2 are 56.6, 31.3 and 55.3, respectively.