气体膜分离用过渡金属有机络合物聚酰亚胺杂化材料的研究

用三苯二醚四酸二酐 (HQDPA)或二苯酮四酸二酐 (BTDA)与二氨基二苯甲烷 (MDA)缩聚合成出聚酰胺酸溶液 ,将此溶液与过渡金属有机络合物共混 ,再经热亚胺化即可制备出一类新型的气体膜分离用过渡金属有机络合物 聚酰亚胺杂化材料 .对所得杂化材料的各项性能进行了研究 ,结果表明 ,制得的杂化材料保持了聚酰亚胺良好的力学性能、耐热性能和耐溶剂性能 .用广角X 射线衍射和液体天平对所得材料的结构进行了表征 ,结果表明 ,过渡金属有机络合物的加入能够增加聚酰亚胺材料的分子链间距 .因此 ,与相应的聚酰亚胺相比 ,杂化材料的透气系数增大而透气选择性变化不大 .     

小分子添加剂在气体分离膜中的应用进展

综述了小分子添加剂在气体分离膜研究中的应用进展,重点介绍了钴金属络合物和小分子液晶对提高膜渗透选择性能的特殊作用。     

温度对含硅聚酰亚胺膜气体分离性能的影响

合成了次联苯基型合硅聚酰亚胺（ＳＩＤＡ－ＢＤＡ），研究了其均质膜对Ｈ２，Ｏ２和Ｎ２的透过分离性能与温度的关系，随着温度的升高，气体的透过系数和扩散系数增大，而溶解系数和选择系数则降低，此外，我们还讨论了气体在膜中的透过活化能，扩散活化能和吸着热。     

溴代聚-4-甲基戊烯-1的溶解性能及其膜的形态结构和结晶状态

<正> 迄今为止,用于气体分离的高分子膜,其气体透过速率和选择分离系数仍不够高。究其原因,一是膜材料的气体透过系数较低;二是某些气体透过系数较高的高分子材料又难以形成超薄膜层。     

含叔丁基聚酰亚胺均质膜的气体分离性能

采用高温“一步法”缩聚合成了一系列含叔丁基的可溶性芳香聚酰亚胺树脂, 然后通过溶液浇注法制得相应均质薄膜, 并对其气体分离性能进行了测试, 同时研究了二酐结构和温度对聚酰亚胺均质膜气体分离性能的影响. 结果表明, 对于H₂, N₂, O₂, CO₂和CH₄ 等5种气体, 含叔丁基聚酰亚胺均质膜不仅表现出良好的透气性, 而且具有较高的气体透过选择性, 4,4'-(六氟异丙烯)二酞酸酐(6FDA)和均苯四甲酸二酐(PMDA)两类聚酰亚胺均质膜的气体分离性能最佳. 除CO₂外, 这两类聚酰亚胺均质膜的气体渗透系数随温度升高而升高, 而所有测试气体在这两种均质膜中的扩散系数和溶解度系数均随温度升高而增大.     

聚酰亚胺、聚砜、聚醚砜及其共混改性中空纤维膜用于醇/醚气相分离的研究

甲醇／ 甲基叔丁基醚的分离是目前具有实用意义的重要研究课题之一,采用气流吹扫式操作,研究了聚酰亚胺、不同结构的聚砜中空纤维膜在不同操作条件下,对甲醇／ 甲基叔丁基醚气相混合体系的分离性能,也研究共混改性对分离膜性能的影响。结果表明,各种材料的膜具有相近的分离行为,即随着气相中甲醇含量的增加,透过通量逐渐增大而分离系数逐渐减小,聚酰亚胺膜具有适中的透过通量,但具有很高的分离系数,在甲醇浓度低于２０ ％ 时,分离系数可达数千。采用聚醚砜共混改性的聚酰亚胺膜在未明显降低透过通量的条件下,使醇／ 醚分离系数大幅度提高,有很好的应用前景。     

等离子体处理对有机硅膜气体透过性能的影响

本文研究了有机硅膜经等离子体处理和等离子体聚合沉积后,气体透过性能的变化。以及放置一段时间后,随着等离子体处理效果的变化,膜的气体透过性能的改变。结果表明无论是Ar等离子体处理的有机硅膜,还是八甲基环四硅氧烷(D_4)等离子体聚合沉积的有机硅膜,其气体透过性能都发生了明显的变化。即经等离子体处理后,膜的气体透过系数下降,选择分离系数上升。在放置一段时间后,其气体透过系数和选择分离系数均表现出有回复的趋势。因此,等离子体处理对膜的气体透过性能的影响随放置时间而变化。     

含脂肪链聚苯并咪唑的合成及其气体透过性能

对含脂肪链聚苯并咪唑的聚合反应进行了比较系统的研究，在此基础上，合成了一系列含脂肪链聚苯并咪唑．以甲酸为溶剂，在减压下，制备了聚合物的均质膜．对聚合物的气体选择透过性能进行了研究，并从化学结构与气体透过性能关系的角度进行了讨论，发现同一聚合物对不同气体的透过系数符合一般玻璃态聚合物的规津；增加柔性链段中亚甲基数目，可提高聚合物的气体透过系数，降低分离系数；刚性链段中引入柔性基因，可增大气体透过系数；温度升高，聚合物的气体透过系数提高，分离系数一般下降．     

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.     

聚酰亚胺,聚砜,聚醚砜及其共混改性中空纤维膜用于醇／醚气？…

甲醇／甲基叔丁基醚的分离是目前具有实用意义的重要研究课题之一,采用气流哆扫式操作,研究了聚酰亚胺、不同结构的聚砜中空纤维膜在不同操作条件下,对甲醇／甲基叔丁基醚气相混合体系的分离性能,也研究共混改性对分离膜性能的影响。结果表明,各种材料的膜具有相近的分离行为,即随着气相中甲醇含量的增加,透过通量逐渐增大而分离系数逐渐减小,聚酰亚胺膜具有适中的透过通量,但具有很高的分离系数,在甲醇浓度低于２０％时,     

Two‐Dimensional Microporous Material‐based Mixed Matrix Membranes for Gas Separation

Since the discovery of graphene and its derivatives, the development and application of two‐dimensional (2D) materials have attracted enormous attention. 2D microporous materials, such as metal‐organic frameworks (MOFs), covalent organic frameworks (COFs), graphitic carbon nitride (g‐C₃N₄) and so on, hold great potential to be used in gas separation membranes because of their high aspect ratio and homogeneously distributed nanometer pores, which are beneficial for improving gas permeability and selectivity. This review briefly summarizes the recent design and fabrication of 2D microporous materials, as well as their applications in mixed matrix membranes (MMMs) for gas separation. The enhanced separation performances of the membranes and their long‐term stability are also introduced. Challenges and the latest development of newly synthesized 2D microporous materials are finally discussed to foresee the potential opportunities for 2D microporous material‐based MMMs.     

含有联苯侧基聚乙炔的合成及其气体渗透性能

合成了含有取代联苯及烷基硅取代基的二芳基乙炔单体（1a~1d）,以TaCl5-n-Bu4Sn作催化剂聚合得到聚合物2a、2b和2d。 所得聚合物在常规有机溶剂中具有良好的溶解性。 用聚合物2a和2b的甲苯溶液浇铸制备了均质膜。 采用三氟乙酸对聚合物2a和2b膜进行去硅化反应,制备了不溶性膜3a和3b。 热重分析表明,所得聚合物均具有高的热稳定性,在空气中的热失重起始温度分别为340和430 ℃。 聚合物2a和2b的氧气渗透系数（PO2)分别为260和390 barrers,去硅化膜3a和3b的PO2分别下降至73和180 barrers。 聚合物膜的O2/N2分离系数为2.4~3.3,并随PO2的增加而减小。 由气体在聚合物膜中的扩散系数和溶解系数的测定,扩散系数的降低是导致去硅化膜气体渗透系数下降的主要原因。     

PREPARATION AND CHARACTERIZATION OF POLYSULFONE AND POLYETHERSULFONE MEMBRANES FOR CALCIUM (Ca2+) AND MAGNESIUM (Mg2+) SEPARATION BY COMPLEXATION ULTRAFILTRATION

ABSTRACT

Asymmetric ultrafiltration membranes were synthesized from locally available polysulfone and polyethersulfone polymers using aprotic solvents and organic additives by the phase inversion method. The membranes were characterized in terms of pure water permeability, separation behavior with respect to polyethylene glycols of various molecular weights and electrolytes. The suitability of using polyethyleneimine (PEI) for selective removal of calcium and magnesium salts by an ultrafiltration process was studied in terms of optimum polymer loading at reasonable permeate flux, irreversible adsorptive fouling of the macromolecular ligand on the polymer as functions of solution pH and ionic strength, and metal ion separation as a function of concentration and pressure. Direct electron microscopic observation of fresh, as well as fouled, membranes are presented.     

A Metal Chelating Porous Polymeric Support: The Missing Link for a Defect‐Free Metal–Organic Framework Composite Membrane

Since the discovery of size‐selective metal–organic frameworks (MOFs), researchers have tried to incorporate these materials into gas separation membranes. Impressive gas selectivities were found, but these MOF membranes were mostly made on inorganic supports, which are generally too bulky and expensive for industrial gas separation. Forming MOF layers on porous polymer supports is industrially attractive but technically challenging. Two features to overcome these problems are described: 1) a metal chelating support polymer to bind the MOF layer, and 2) control of MOF crystal growth by contra‐diffusion, aiming at a very thin nanocrystalline MOF layer. Using a metal chelating poly‐thiosemicarbazide (PTSC) support and adjusting the metal and organic ligand concentrations carefully, a very compact ZIF‐8 (ZIF=zeolitic imidazolate framework) layer was produced that displayed interference colors because of its smooth surface and extreme thinness—within the range of visible light. High performances were measured in terms of hydrogen/propane (8350) and propylene/propane (150) selectivity.     

Polyphenylsulfone/multiwalled carbon nanotubes mixed ultrafiltration membranes: Fabrication,characterization and removal of heavy metals Pb2+, Hg2+, and Cd2+ from aqueous solutions

Polyphenylsulfone/multiwalled carbon nanotubes/polyvinylpyrrolidone/1-methyl-2-pyrrolidone mixed matrix ultrafiltration flat-sheet membranes were fabricated via phase inversion process to inspect the heavy metals separation efficacy from aqueous media. Fabricated membranes cross-sectional morphological changes and the topographical alterations were assessed with Scanning electron microscopy (SEM) and atomic force microscopy (AFM). Particularly, MWCNTs assisted membranes exhibited better permeability ability as well as heavy metal removal enactment than virgin membrane. The dead-end filter unit was engaged in current research to examine the permeability and heavy metal removal competence of membranes. With the continuous enhancement of MWCNTs wt% in a polymer matrix, significant enhancement was observed with pure water flux study, from 41.69 L/m² h to >185 L/m² h as well as with the heavy metals separation study. Added additive MWCNTs can impact the pore sizes in membranes. The heavy metal separation results achieved, the membrane with 0.3 wt% of MWCNTs (PCNT-3) exhibited >98%, >76% and >72% for Pb²⁺, Hg²⁺ and Cd²⁺ ions, respectively. Overall, MWCNTs introduced PPSU membranes exposed best outcomes with heavy metals contained wastewater treatment.     

Chemically Stable Covalent Organic Framework (COF)‐Polybenzimidazole Hybrid Membranes: Enhanced Gas Separation through Pore Modulation

Highly flexible, TpPa‐1@PBI‐BuI and TpBD@PBI‐BuI hybrid membranes based on chemically stable covalent organic frameworks (COFs) could be obtained with the polymer. The loading obtained was substantially higher (50 %) than generally observed with MOFs. These hybrid membranes show an exciting enhancement in permeability (about sevenfold) with appreciable separation factors for CO₂/N₂ and CO₂/CH₄. Further, we found that with COF pore modulation, the gas permeability can be systematically enhanced.     

Remarkably Enhanced Gas Separation by Partial Self‐Conversion of a Laminated Membrane to Metal–Organic Frameworks

Separation methods based on 2D interlayer galleries are currently gaining widespread attention. The potential of such galleries as high‐performance gas‐separation membranes is however still rarely explored. Besides, it is well recognized that gas permeance and separation factor are often inversely correlated in membrane‐based gas separation. Therefore, breaking this trade‐off becomes highly desirable. Here, the gas‐separation performance of a 2D laminated membrane was improved by its partial self‐conversion to metal–organic frameworks. A ZIF‐8‐ZnAl‐NO₃ layered double hydroxide (LDH) composite membrane was thus successfully prepared in one step by partial conversion of the ZnAl‐NO₃ LDH membrane, ultimately leading to a remarkably enhanced H₂/CH₄ separation factor and H₂ permeance.     

Gas transport properties of hyperbranched polyimide/hydroxy polyimide blend membranes

Gas transport properties of novel hyperbranched polyimide/hydroxy polyimide blends and their silica hybrid membranes were investigated. Gas permeability coefficients of the blend membranes showed positive deviation from a semilogarithmic additive rule. The enhanced gas permeability were resulted from the increase in free volume elements caused by the intermolecular interaction between terminal amine groups of the hyperbranched polyimide and hydroxyl groups of the hydroxy polyimide backbone. Additionally, CO₂/CH₄ separation ability of the blend membranes was markedly promoted by hybridization with silica. The remarkable CO₂/CH₄ separation behavior was considered to be due to characteristic distribution and interconnectivity of free volume elements created by the incorporation of silica. For the hyperbranched polyimide/hydroxy polyimide blend system, polymer blending and hybridization techniques synergistically provided the excellent CO₂/CH₄ separation ability.     

Uniformly Distributed Mixed Matrix Membranes via a Solution Processable Strategy for Propylene/Propane Separation

Aggregation of filler particles during the formation of mixed matrix membranes is difficult to avoid when filler loadings exceed a 10–15 wt %. Such agglomeration usually leads to poor membrane performance. In this work, using a ZIF-67 metal–organic framework (MOF) as filler along with surface modification of Ag₄tz₄ to improve processability and selective olefin adsorption, we demonstrate that highly loaded with a very low agglomeration degree membranes can be synthesized displaying unmatched separation selectivity (39) for C₃H₆/C₃H₈ mixtures and high permeability rates (99 Barrer), far surpassing previous reports in the literature. Through molecular dynamics simulation, the enhanced compatibility between ZIF-67 and polymer matrix with adding Ag₄tz₄ was proven and the tendency in gas permeability and C₃H₆ selectivity in the mixed matrix membranes (MMMs) were well explained. More importantly, the membrane showed a wide range of pressure and temperature resistance, together with remarkable long-term stability (>900 h). The modification method might help solve interface issues in MMMs and can be extended to the fabrication of other fillers to achieve high performance MMMs for gas separation.     

Rational Tuning of Zirconium Metal–Organic Framework Membranes for Hydrogen Purification

The effect of organic ligands on the separation performance of Zr based metal–organic framework (Zr‐MOF) membranes was investigated. A series of Zr‐MOF membranes with different ligand chemistry and functionality were synthesized by an in situ solvothermal method and a coordination modulation technique. The thin supported MOF layers (ca. 1 μm) showed the crystallographic orientation and pore structure of original MOF structures. The MOF membranes show excellent selectivity towards hydrogen owing to the molecular sieving effect when the bulkier linkers were used. The molecular simulation confirmed that the constricted pore apertures of the Zr‐MOFs which were formed by the additional benzene rings lead to the decrease in the diffusivity of larger penetrants while hydrogen was not remarkably affected. The gas mixture separation factors of the MOF membranes reached to H₂/CO₂=26, H₂/N₂=13, H₂/CH₄=11.