【作者】 赵卷；

【导师】 王志；

【作者基本信息】 天津大学 ， 化学工程， 2007， 博士

【摘要】 分离与回收CO2是21世纪最为重要的涉及能源、资源和环境的课题之一。分离CO2的固定载体膜尚属新的研究领域,其膜材料的开发和制膜工艺的改善是亟待解决的问题。本文探索了用界面聚合法制备分离CO2固定载体复合膜。首次以水相-油相法界面聚合研制成功五种CO2固定载体复合膜。这五种复合膜分别以二乙烯三胺(DETA)、三乙烯四胺(TETA)、四乙烯五胺(TEPA)、多乙烯多胺(PEPA)和聚乙烯亚胺(PEI)为水相单体或预聚物,均苯三甲酰氯(TMC)为油相单体,聚砜(PS)或聚醚砜(PES)超滤膜为基膜。利用多种测试手段分析了所制膜的结构。考察了膜对CO2/CH4和CO2/N2体系的透过分离性能。系统研究了各种条件对膜结构和性能的影响规律。结果表明,五种复合膜均含有大量胺基,表面粗糙致密,具有超薄分离层且分离层与支撑层具有互嵌结构。对TETA单体,适宜的制膜条件是:PS为基膜,65～70oC下热处理10～15min;2～2.8wt% TETA浓度,0.2～1.2wt% TMC浓度, 2～10min TETA浸泡时间,3～4min界面聚合时间,添加浓度不小于0.4wt%的酸吸收剂(NaOH、Na2CO3或TEA)。随着胺单体链长的增加,DETA-TMC、TETA-TMC、TEPA-TMC和PEPA-TMC复合膜透气性依次增大,分离因子依次减小。一般地,随着进料压力的升高或进料温度的降低,CH4(N2)渗透速率升高,CO2渗透速率和CO2/CH4(CO2/N2)分离因子降低。五种复合膜的透过选择性和耐压能力综合指标明显高于文献报道的其它固定载体膜。如,进料温度30oC,进料压力1.1atm时,对混合气体CO2/CH4 (体积比10/90),DETA-TMC/PS、TETA-TMC/PS、TEPA-TMC/PS和PEPA-TMC/PS复合膜的CO2渗透速率分别可达5.85×10-6、1.47×10-5、2.38×10-5和3.18×10-5cm3(STP)cm-2s-1cmHg-1,相应的CO2/CH4分离因子为124、96、76和64。同样的复合膜,进料压力分别为10.6atm、10.4atm、10.2atm和9.9atm时,其CO2渗透速率分别可达4.86×10-6、9.20×10-6、1.34×10-5和1.65×10-5 cm3(STP)cm-2s-1cmHg-1,相应的CO2/CH4分离因子为56、42、35和31。膜对CO2/N2 (体积比20/80)的透过选择性更好。对PEI-TMC/PS复合膜,进料压力为1.1atm时,CO2渗透速率可达3.13×10-5cm3(STP)cm-2s-1cmHg-1,CO2/CH4分离因子是81;进料压力10.9atm时,CO2渗透速率和CO2/CH4分离因子分别可达2.34×10-5 cm3(STP)cm-2s-1cmHg-1和37。尝试用油相-水相法界面聚合制备了TETA-TMC/PES固定载体复合膜,研究比较了水相-油相法和油相-水相法两种工艺及所制膜结构和性能的不同特点。结果表明,前者制备的复合膜表面更粗糙、分离层更薄,制膜工艺较复杂但分离性能更好。更多还原

【Abstract】 Separation and reclaim of CO2 is one of the most important subjects on energy, resource and environment in 21 century. Fixed carrier membrane for CO2 separation is a new research field in which both the development of membrane material and the improvement of membrane preparation technique are urgent. This study made attempts to develop fixed carrier membranes for CO2 removal prepared by interfacial polymerization (IP).Five kinds of fixed carrier composite membranes were developed by IP from aqueous phase to organic phase, with diethylenetriamine (DETA), trimethylene tetramine (TETA), tetraethyleneamine (TEPA), polyethylene polyamide (PEPA) and polyethylenimine (PEI) as monomers or prepolymer of aqueous phase, trimesoyl chloride (TMC) as monomer of organic phase, polysulfone (PS) or polyethersulfone (PES) ultrafiltration membranes as supports. Several techniques were employed to characterize the structure of the membranes. The permselectivities of the membranes were measured with CO2/CH4 as well as CO2/N2. Influence of various parameters on membrane structure and performance were studied. The results show that these membranes contain a lot of amine groups, the IP layers of the composite membranes are dense, rough and very thin, and the adhesion between the IP layer and the porous support is good due to penetration of the IP layer into the porous support. Composite membranes with TETA as amine monomer have good performance with 10-15min heat-treatment at 65-70oC, 2-2.8wt% TETA concentration, 0.2-1.2wt% TMC concentration, 2-10min soaking in TETA solution, 3-4min IP time, more than 0.4wt% acid acceptor concentration of Na2CO3, NaOH or TEA. With amine chain longer, gas permeance of the membranes with various amines increases and the selectivity of the membranes decreases. Generally, with feed pressure increasing or temperature decreasing, CH4 or N2 permeance increases and CO2 permeance decreases which result in a decrease in CO2/CH4 or CO2/N2 selectivity.These composite membranes have excellent comprehensive performances including permselectivties and pressure stabilities, which are better than that of other fixed carrier membranes reported in literatures. For example, for feed gas containing 10vol% CO2 and 90vol% CH4, at 30oC and 1.1atm of feed gas pressure ,DETA-TMC/PS, TETA-TMC/PS, TEPA-TMC/PS and PEPA-TMC/PS composite membranes display CO2 permeance of 5.85×10-6, 1.47×10-5, 2.38×10-5 and 3.18×10-5 cm3(STP)cm-2s-1cmHg-1 and CO2/CH4 selectivity of 124, 96, 76 and 64. At 10.6atm, 10.4atm, 10.2atm and 9.9 atm of feed pressure,these membranes have CO2 permeance of 4.86×10-6, 9.20×10-6, 1.34×10-5 and 1.65×10-5 cm3(STP)cm-2s-1cmHg-1 and CO2/CH4 selectivity of 56, 42, 35 and 31. These membranes have better permselectivity for feed gas containing 20vol% CO2 and 80vol% N2. At 1.1atm of feed pressure, PEI-TMC/PS composite membrane has a CO2 permeance of 3.13×10-5 cm3(STP)cm-2s-1cmHg-1 and CO2/CH4 selectivity of 81, at 10.9atm of feed pressure, this membrane has a CO2 permeance of 2.34×10-5cm3(STP)cm-2s-1cmHg-1 and CO2/CH4 selectivity of 37.TETA-TMC/PES fixed carrier membranes were prepared by IP from organic phase to aqueous phase. The method of IP methods from aqueous phase to organic phase and the method of IP from organic phase to aqueous phase, and the corresponding membrane structure and performance were compared. The results show that the method of IP from aqueous phase to organic phase is more complex, and the composite membranes prepared by this method present rougher surface, thinner IP layer, and better permselectivity.更多还原