【作者】 原野；

【导师】 王纪孝； 王志； 毛松柏；

【作者基本信息】 天津大学 ， 化学工程， 2020， 硕士

【摘要】 高效分离CO₂是温室气体减排和能源气体提纯与净化等的重要环节。膜分离技术具有能耗低、操作弹性大和环境友好等特点,应用前景广阔。但是,由于目前商品CO₂分离膜渗透选择性能不够高,限制了其大规模应用。因此开发出具有良好CO₂渗透选择性能的分离膜具有重要意义。促进传递膜以功能基团为载体,可以实现CO₂的高效分离。聚乙烯基胺（PVAm）是一种典型的促进传递膜材料。然而,商品PVAm水解度极高,链段间氢键作用力过强,导致其结晶度很高,难以制备成高性能分离膜。因此,需要对PVAm的合成工艺进行改进,以提高其所制膜的渗透选择性能。此外,为进一步提高膜分离性能,多孔材料被引入PVAm中以制备混合基质膜。但是,大多数多孔材料与PVAm基质之间的界面相容性较差,而经过修饰后的多孔材料很难保留其原有的气体传递通道,因此膜分离性能的提升受到限制。本文针对以上问题,进行了两方面工作。首先,利用盐酸作为水解催化剂,通过调节盐酸浓度、水解温度和水解时间,优化PVAm的合成工艺,对PVAm的水解度进行调控。将其刮涂在改性聚砜（m PSf）超滤膜上,制得PVAm/m PSf复合膜,并分别以CO₂/N₂、CO₂/CH₄和CO₂/H₂混合气为原料,对其CO₂分离性能进行了测试。结果表明,当盐酸浓度、水解时间和水解温度分别为10 wt%、70°C和4 h时,制得的PVAm具有较低的结晶度和较多的有效载体含量,所制膜的CO₂分离性能较高。其次,采用改进的聚合物定向化学合成法（PDCS）合成了一种具有高氨基密度的多孔材料——高价金属诱导的多孔聚合物（HMMP-1）。由于高价金属Cr³⁺和聚乙烯亚胺的存在,HMMP-1具有优异的碱稳定性和界面相容性。将HMMP-1与上述高性能PVAm共混,刮涂在m PSf超滤膜上,制备了HMMP-1-PVAm/m PSf混合基质复合膜。由于优异的界面相容性,HMMP-1在膜中保留了合适尺寸的促进传递孔道结构。分别用CO₂/N₂、CO₂/CH₄和CO₂/H₂混合气体系测试该膜的CO₂渗透选择性能,结果表明,当HMMP-1添加量为44.4 wt%时,HMMP-1-PVAm/m PSf膜具有极高的CO₂/N₂、CO₂/CH₄和CO₂/H₂分离性能。技术经济性分析表明该膜有望应用于烟道气碳捕集的工业分离过程中。更多还原

【Abstract】 Efficient separation of CO₂ plays an important role in greenhouse gas emissions reduction and energy gases upgradation and purification.Membrane separation technology with broad application prospects has the characteristics of low energy consumption,large operation flexibility and environmental friendliness.However,the commercial CO₂ separation membranes with low CO₂ permselcetivity have limited large-scale application.Therefore,it is important to develop separation membranes with excellent CO₂ perm-selectivity.Facilitated transport membranes with functional groups as carriers can achieve efficient CO₂ separation.Polyvinylamine（PVAm）is a typical kind of material for facilitated transport membranes.However,commercialized PVAm with extremely high hydrolysis degree is accompanied by the strong intermolecular hydrogen bonding force,resulting in the high crystallinity.Such kind of PVAm is difficult to be used to prepare the high-performance CO₂ separation membrane.Therefore,there is a need to improve the production process of PVAm to improve the permselectivity of the membranes made by it.In addition,in order to further improve the separation performance,porous materials are introduced into PVAm to prepare mixed matrix membranes（MMMs）.However,the interface compatibility between most porous materials and PVAm matrix is usually not good enough,and the modified porous materials are difficult to retain its inherent gas transfer channels,thus the increase of membrane separation performance is limited.In this paper,two aspects of work have been carried out to solve the problems mentioned above.Firstly,with HCl served as the hydrolysis catalyst,the synthesis process of PVAm was optimized to adjust the hydrolysis degrees of PVAm by adjusting the HCl concentration,hydrolysis temperature and hydrolysis duration.The regulated PVAm was coated on the modified polysulfone ultrafiltration membrane（m PSf）to prepare PVAm/m PSf composite membranes,which are tested with CO₂/N₂,CO₂/CH₄ and CO₂/H₂ mixed gases respectively.The results show that the PVAm synthesized under HCl concentration at 10 wt%,hydrolysis temperature at 70℃and hydrolysis duration at 4 h has a relatively low crystallinity and a large number of carriers,by which the membranes made possess a high CO₂ separation performance.Secondly,a new kind of porous materials with high amine density—high-valence metal-induced porous polymer（HMMP-1）was synthesized by using a modified polymer-directed chemical synthesis（PDCS）method.Due to the existance of high-value metals Cr³⁺and polyethyleneimine（PEI）,HMMP-1 nanoparticles possess outstanding alkaline stability and polymer interfacial compatibility.Then,HMMP-1nanoparticles are blended with the high-performance PVAm prepared above to prepare the HMMP-1-PVAm/m PSf composite MMMs with facilitated transport characteristics.Due to the excellent interfacial compatibility of HMMP-1 nanoparticles,the membranes retain the appropriately sized amine-rich nanochannels for facilitated transport.The membranes are all tested with the CO₂/N₂,CO₂/CH₄ and CO₂/H₂ mixed gases respectively.The results show that HMMP-1-PVAm/m PSf membranes exhibit extremely high CO₂/N₂,CO₂/CH₄,and CO₂/H₂ mixed gases separation performance when the HMMP-1 loading is at 44.4 wt%.A techno-economic evaluation suggests that this membrane is feasible for carbon capture from post-combustion flue gas.更多还原