自具微孔高分子气体分离膜的结构调控与改性研究

自具微孔高分子（polymers of intrinsic microporosity, PIMs）是近年来出现的一种新型有机微孔材料,由含有扭曲结构的刚性单体聚合而成,具有比表面积高、化学和物理性质稳定、微孔结构可控等优点,在均相催化、氢气储存等方面表现出巨大的应用潜力。因其优越的气体分离性能,PIMs气体分离膜更是吸引了众多研究者的关注,发展迅速。本文总结了PIMs的分类及其在气体分离膜中的应用,重点介绍了PIMs气体分离膜的结构调控与改性方面的研究进展,分析了PIMs的分子结构与气体分离性能间的内在关联,最后提出了目前研究中存在的一些问题并对其发展做出了简要的评述。     

共轭微孔聚合物膜的制备策略及其分离应用

降低工业分离过程的能耗为缓解全球能源紧缺问题提供了有效途径. 相比传统工业分离技术, 膜分离技术能耗低、经济效益高, 开发高效的膜材料是提升膜分离性能的重要手段. 共轭微孔聚合物(CMP)膜具有刚性永久超微孔道、高孔隙率、孔结构及化学环境可调控、交联骨架稳定性好等优势, 在分离领域具有良好的应用前景. 概述了近年来CMP膜的制备方法并简要对比了其优缺点, 阐述了CMP膜在气体分离、有机溶剂纳滤、离子筛分和手性分离等领域的分离机理和研究进展, 为开发新型具有良好分离性能的CMP膜材料提供研究思路.     

CO_2捕集炭膜的前驱体结构设计及性能

从分子结构设计出发,合成了一系列新型刚性、高自由体积的聚酰亚胺炭膜前驱体,并制备了炭膜.采用热重分析(TGA)、傅里叶变换红外光谱(FTIR)、X射线衍射(XRD)和高分辨透射电子显微镜(HRTEM)研究了不同聚酰亚胺前驱体的热分解特性及在热解炭化过程中化学结构、微结构的变化规律;测试了所制备炭膜的气体分离性能.结果表明,前驱体的自由体积分数显著影响炭膜的气体分离性能;聚合物结构越具刚性,自由体积越大,所得炭膜结构越疏松,极微孔道尺寸越大,越有利于气体分子在炭膜极微孔道中的渗透、扩散与传输.其中,刚性大体积基团芴基、酚酞cardo基团和六氟异丙基的引入能有效破坏分子链间的堆积,提高聚合物的自由体积,所形成炭膜的结构较疏松,均表现出优异的气体渗透性和分离选择性,超越了Robeson上限,解决了传统炭膜气体渗透性能低的问题.特别是采用羟基官能化聚酰亚胺前驱体制备的炭膜在保持较高气体分离选择性的同时,CO_2气体的渗透性高达24770 Barrer(1 Barrer≈7.5×10-18m2·s-1·Pa-1),可实现对CO_2的有效分离和捕集,展现出良好的商业化应用前景.     

钴掺杂二氧化硅膜的制备、表征及氢气分离性能

采用正硅酸乙酯(TEOS)和Co(NO3)2.6H2O为前驱体通过溶胶-凝胶法制备掺钴微孔二氧化硅膜,研究钴在二氧化硅膜材料中的存在状态、膜材料孔结构以及膜材料的气体渗透和分离性能。结果表明钴元素以Si-O-Co的形式存在于SiO2骨架之中,掺杂Co 10%的微孔SiO2膜具有典型的微孔结构,其孔体积为0.119 cm3·g-1,平均孔径在0.52 nm左右且孔径主要分布在0.4～0.55 nm之间。氢气在膜材料中的输运低温下遵循Knudsen扩散机理,高于100℃时遵循活化扩散机理,300℃时膜材料的H2渗透率达到6.41×10-7 mol.m-2.s-1.Pa-1,H2/CO2分离系数达到6.61,高于Knudsen扩散的理想分离系数。     

含有聚醚链段的可溶性聚酰亚胺气体分离膜材料及其性能

将4,4'-六氟亚异丙基-邻苯二甲酸酐(6FDA)和1,3-苯二胺(mPDA)与二端氨基聚醚缩聚, 得到含有聚醚柔性链段的聚酰亚胺气体分离膜材料. 所合成的共聚聚酰亚胺在N-甲基吡咯烷酮(NMP)和四氢呋喃(THF)等有机溶剂中具有良好的溶解性能. 研究了O2, N2, H2, CH4和CO2在聚酰亚胺均质膜中的渗透性能, 考察了二端氨基聚醚的含量、链长和化学结构对气体渗透性能的影响. 结果表明, 聚醚链段的引入增大了气体的扩散系数, 气体的渗透系数显著增大; 聚醚链段与CO2相对较强的相互作用, 增大了对CO2/N2的溶解选择性, CO2/N2的分离性能优于CO2/CH4, 同时CO2比H2优先透过膜.     

具有不对称孔道结构的小介孔二氧化硅粒子的合成及其高分子杂化膜的构建

利用手性阴离子酸表面活性剂, 采用软模板法制备了具有不对称孔道结构的小介孔二氧化硅(SiO₂)粒子. 将小介孔SiO₂粒子引入聚偏四氟乙烯(PVDF)和聚酰亚胺(PI)中构建了两种有机/无机杂化膜. 利用傅里叶变换红外光谱(FTIR)、 透射电子显微镜(TEM)、 扫描电子显微镜(SEM)和比表面积分析等表征了小介孔SiO₂粒子和有机/无机杂化膜的微结构, 并通过超滤实验和气体渗透实验分别考察两种杂化膜的性能. 研究结果表明, 表面含有大量亲水基团的小介孔SiO₂粒子具有规则有序排列的孔道结构, 该孔道结构呈现螺旋扭曲和不对称性. 构建的两种有机/无机杂化膜的极性显著提升, 进而有效增强了PVDF杂化膜的膜通量和抗污染性能及PI杂化膜对CO₂气体的分离性能, 克服了高分子膜的博弈效应(Trade-off效应). 另外, SiO₂的小介孔孔道还可以在PI杂化膜中引入优先通过CO₂分子的限域传质通道, 加速了CO₂气体在杂化膜中扩散. 但过多小介孔SiO₂粒子的加入导致其在高分子基质中团聚, 削弱杂化膜的极性和亲水性, 从而降低了两种杂化膜的分离性能.     

含二氮杂萘酮结构微孔聚合物的研究进展

微孔有机聚合物具有比表面积大、骨架密度低、结构多样、孔隙结构和功能易于调控的优势,在CO2的吸附和分离领域展现出了非常好的应用前景,成为近年来多孔材料领域的研究热点之一。二氮杂萘酮及其衍生物是一种非对称芳杂环结构,具有刚性、扭转和非共平面的结构特点,能够阻碍链的紧密堆砌,有效增加链间自由体积,从而有利于孔隙结构的形成。本文综述了以二氮杂萘酮结构为核心的共价三嗪基骨架材料和自具微孔聚合物的设计、合成及气体吸附分离性能的研究进展,研究结果表明,利用二氮杂萘酮结构可以构筑出具有较高比表面积的微孔有机聚合物材料,并且杂环结构可增加材料骨架与CO2分子之间的亲和力,从而改善材料在低压下的吸附分离性能;可通过灵活的结构设计和简便的原料制备方法,降低材料的制备成本,具有很好的潜在应用前景。     

杂萘联苯聚芳醚功能膜的研究进展

随着膜分离技术、质子交换膜燃料电池技术和液流电池储能技术等的发展,膜材料的研究开发也越来越受到人们的重视。杂萘联苯聚芳醚是一类性能优良的高分子膜材料,由于分子主链上含有全芳非共平面扭曲链结构,具有较好的耐化学稳定性和耐热性,且可溶解于N－甲基－2－吡咯烷酮、N,N－二甲基乙酰胺等常用制膜溶剂,在耐高温分离膜和离子交换膜...     

高分子气体分离膜材料的化学结构与气体透过性能之间的关系

本文以硅橡胶和聚酰亚胺为基础,从高分子的化学组成、分子链段的运动能力、侧基的大小及其作用等几个方面,讨论了聚合物的化学结构对其均质膜的气体选择透过性能的影响,以溶解扩散过程对气体分离膜材料的透气行为进行了剖析,井简述高分子化学结构对其成膜时结晶情况的影响及对气体透过的作用;还概述了气体分离膜科学发展的历史以及基本原理.     

含聚醚链段聚酰亚胺膜的制备及气体分离性能

利用均苯四甲酸二酐（PMDA）与4,4’-二氨基二苯醚（ODA）和聚醚胺（PPO, Mn～2000）共聚合,合成聚酰胺酸前驱体,经热处理得到一系列含PPO链段的聚酰亚胺薄膜.研究了PPO链段的引入对薄膜结构及气体分离性能的影响.结果表明,在芳香族聚酰亚胺中引入柔性链段PPO有利于气体分子的传输.得益于PPO链段在分离膜内部形成的微相分离结构,气体分子在分离膜内的扩散系数随PPO含量的增加显著提升.当PPO含量为65 wt%时,PPO链段在分离膜内仍呈现非晶相,CO₂渗透系数高达131.61 Barrer,比PMDA/ODA均聚聚酰亚胺薄膜提高22倍.同时,得益于聚醚链段对CO₂独特的亲和作用,随着PPO含量的提高,分离膜对CO₂/N₂的分离系数由18.77提高至30.12.结果表明PPO链段的引入对于调控聚酰亚胺膜的结构和气体分离性能具有重要作用.     

二氧化碳和丙烯直接合成甲基丙烯酸的NiPMo/TiO2催化剂的研究

用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%.     

Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction

In the context of the preparation of camptothecin and luotonin A analogs, the synthesis of some key keto-precursors and their use in Friedländer condensation are described. This paper also focuses on the stability of these keto intermediates and emphasizes the major differences between indolizinones and pyrroloquinazolinones series. Noteworthy is also the report of some original structures isolated as by-products of some experiments.     

CoFe2O4自形成磁性液体场致结构化对磁化的影响

The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula.     

Highly regioselective Buchwald–Hartwig amination at C-2 of 2,4-dichloropyridine enabling a novel approach to 2,4-bisanilinopyridine (BAPyd) libraries

The highly regioselective Buchwald–Hartwig amination at C-2 of the cheap and readily accessible reagent, 2,4-dichloropyridine with a range of anilines and heterocyclic amines is described. This new methodology is robust and provides a facile access to 4-chloro-N-phenylpyridin-2-amines on 0.25 mol scale. These intermediates undergo a further Buchwald–Hartwig amination at higher temperature to enable rapid exploration of the chemical space at C-4 and to provide a library of 2,4-bisaminopyridines.     

KMnO4-mediated oxidative CN bond cleavage of tertiary amines: Synthesis of amides and sulfonamides

KMnO₄-mediated oxidative CN bond cleavage of tertiary amines producing secondary amine was introduced, which was trapped by electrophiles (acyl chloride and sulfonyl chloride) to form amides and sulfonamides. The reaction could take place at mild condition, tolerating a wide range of function groups and affording products in moderate to excellent yields.     

Chemistry of heterocyclic compounds at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, over 50 years (Review)

The review contains a concise historical account and information on the most significant researches undertaken by the staff at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences on the Chemistry of Heterocyclic Compounds. Dedicated to Academician of the Russian Academy of Sciences B. A. Trofimov on his 70th jubilee. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1443–1502, October, 2008.     

Sulfur-directed metal-free and regiospecific methyl C(sp3)–H imidation of thioanisoles

Regiospecific and direct imidation of the methyl C(sp³)–H bond of thioanisoles is realized under mild and metal-free conditions with N-fluorobis(benzenesulfonyl)imide as an oxidant and nitrogen source. Proposed mechanism suggests that thionium ion intermediates and a Pummerer-type reaction are involved. The imidation has advantages such as high step-economy, excellent functionality tolerance, and regiospecificity, giving structurally diverse imidation products.     

Selective syntheses of 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones via temperature-dependent Rh(II)-carbenoid-mediated 2H-azirine-ring expansion

The Rh(II)-catalyzed reaction of 2-carbonyl-substituted 2H-azirines with ethyl 2-cyano-2-diazoacetate or 2-diazo-3,3,3-trifluoropropionate provides an easy access to 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones. These compounds can be selectively prepared from the same starting material using temperature as the only varied parameter. The 2-azabuta-1,3-diene intermediate, a common precursor for both heterocyclic products, isomerizes into 2H-1,3-oxazine under kinetic control, while 1H-pyrrol-3(2H)-one is the sole product of the reaction at elevated temperatures. According to DFT-calculations a one-atom oxazine ring contraction involving ring-opening to a 2-azabuta-1,3-diene intermediate, followed by a 1,5- and 1,2-prototropic shift leads to the consecutive formation of imidoylketene and azomethine ylide, which then further undergo cyclization to the pyrrole derivative.     

Synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives

Different approaches for the synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives from simple amino acids have been investigated. A library of 33 precursors for the preparation of N-hydroxy pyrazinones was obtained in moderate to good yields.