脂环-芳香结构微孔聚酰亚胺: 合成、孔结构及有机烃吸附分离性能研究

The present project aims at the adsorption/separation of some important organic alkanes/olefins (aromatic hydyocarbons) and recovery of organic waste gases in petrochemical industry using microporous polymers as adsobents. For this purpose, a series of new wholly cycloaliphatic and cycloaliphatic-aromatic hyper-crosslinked microporous polyimides are designed and synthesized by utilizing cycloaliphatic and aromatic tetraamines to polymerize with rod-like cycloaliphatic dianhydrides with different length-diameter ratios, respectively. Moreover, through the copolymerization of tetraamine with the mixture of cycloaliphatic and aromatic dianhydride, the content of cycloaliphatic or aromatic ring in the cycloaliphatic-aromatic microporous polyimide networks are tunable. The effects of geometric configuration of building blocks on the porous properties such as specific surface area, pore size and distribution of polyimides are studied. The adsorption properties of linear and branched alkanes and olefins with different numbers of carbon atoms, alkane and its corresponding olefin with the same number of carbon atom, linear alkanes and their branched isomers, linear olefins and their branched isomers, olefins with different numbers of C=C double bond and the aromatic/aliphatic hydrocarbons with the similar molecular size are measured and investigated. The roles of pi-pi interaction between olefins (aromatic hydrocarbons) and the aromatic components, and the van der Waals interaction between alkanes and cycloaliphatic components of microporous polymers on the adsorptions of alkanes/olefins (aromatic hydrocarbons) as well as the relationships between the adsorption/separation of organic hydrocarbons and chemical and porous structures of microporous polymers are aslo systematically studied in order to elucidate the effects of chemical environment of porous channels on the adsorption/separation ability of alkanes/olefins (aromatic hydrocarbons), and guide the design and synthesis of microporous polymers for adsorption/separation of organic hydrocarbons in the future.

本课题针对石化工业重要烷烃/烯烃(芳烃)分离纯化及尾气回收等技术需求，采用脂环四胺或芳香四胺分别与长径比不同的脂环族二酐和芳香二酐均聚或共聚，制备高度交联的全脂环结构微孔聚酰亚胺和苯环含量系列可调的脂环-芳香结构微孔聚酰亚胺，研究构造单元几何构型对微孔聚合物孔形貌参数(比表面积、孔径尺寸及分布)的影响；系统研究碳原子数不同的直链烷烃和烯烃、碳原子数相同的烷烃和相应烯烃、直链烷烃和其支链同分异构体、直链烯烃和其支链同分异构体、具有不同C=C双键数目的烯烃以及分子尺寸类似的芳烃/脂环烷烃的吸附性能；研究烯烃、芳烃和烷烃分子与微孔聚合物骨架间pi-pi相互作用和范德华相互作用的差异对烷烃/烯烃(芳烃)吸附分离性能的影响；揭示脂环-芳香微孔聚酰亚胺孔道微化学环境和孔形貌参数与烷烃/烯烃(芳烃) 选择吸附能力之间的内在变化规律，为今后制备高性能微孔聚合物有机烃吸附分离材料提供理论和实验依据。

本项目圆满完成预定目标。已在J. Mater. Chem. A, ACS Appl. Mater. Interfaces,Macromolecules,Chem. Commun. Polym. Chem.等本领域高水平国际学术期刊上发表SCI论文19篇，超出发表学术论文5-8篇的预期目标，后续还有多篇论文随后整理发表。.主要创新性结果如下：.(1) 采用双环[2.2.2]辛-7-烯-2,3,5,6-四羧酸二酐（BCDA）、1,2,4,5-环己烷四甲酸二酐和1,2,3,4-环丁烷四甲酸二酐分别与1,3,5,7-四（4’-氨基苯基）金刚烷和四（4-氨基苯基）甲烷聚合，制备了系列BET比表面积介于25-1108 m2/g的脂环结构微孔聚酰亚胺(sPIs)。在常温常压条件下，sPIs的C2H4/CH4、C2H6/CH4、C3H6/CH4、C3H8/CH4和C3H6/C3H8的吸附选择性分别为15、14、177、82和3，是目前报道的微孔聚酰亚胺材料中最高的。而且，所制备的脂环-芳香型微孔聚酰亚胺的丁二烯的吸附量高达4.64 mmol/g，丁二烯/1-丁烯的吸附选择性为3.2，在有机烃吸附分离方面显示出潜在应用前景。.(2) 利用四面体结构的1,3,5,7-四（4’-氨基苯基）金刚烷与不同摩尔比的双环[2.2.2]辛-7-烯-2,3,5,6-四羧酸二酐和均苯四甲酸二酐共聚，制备出脂环含量可调的微孔聚酰亚胺(cPIs)，所得cPIs的BET比表面积介于814-1108 m2/g。在298 K和相对压力为0.9的条件下，cPIs的苯和环己烷蒸气吸附量分别高达160.3 wt%和85.4 wt%，表现出优异的可挥发有机蒸气吸附捕获能力。.(3) 以脂环结构微孔聚酰亚胺sPI-2为碳化前驱体，经碳化处理后，sPI-2的比表面积从900 m2/g提高到2406 m2/g。此外，在298 K和相对压力仅为0.1的条件下，碳化改性产物显示出很高的苯蒸气吸附量（74.4 wt%）和环己烷蒸汽吸附量（64.8 wt%）。.(4) 成功制备了银离子改性的多孔聚酰亚胺(MPI-Ag）。研究结果表明：在聚合物骨架上引入银离子后，在273 K和1 bar条件下，丙烯对丙烷的吸附选择性由MPI的2.0提高到MPI-Ag的16.3。尤其是，丙烯/甲烷选择性高达3785，是目前报道的多孔材料中最高的。