聚甲基氢硅氧烷基气体分离膜的进展

气体分离膜技术与传统的气体分离技术(如胺吸收、变压吸附、深冷分离等)相比，具有无相变、高效、节能、操作简便、无二次污染等特点，在空气中氧、氮的富集、石油炼制、化学品生产及二氧化碳的捕获等领域中具有极大的应用前景。分离膜作为气体膜分离技术的核心，获得高透过性及高选择性的膜材料是气体分离膜研究中的目标。聚甲基硅氧烷由于具有优异的高气体透过性、较低的获得成本、结构可变性较强等特点，已成为气体分离膜材料的一个重要研究方向。对目前用于气体分离膜的聚甲基硅氧烷基气体分离膜的种类及合成进行了研究，分析并讨论了各种聚甲基硅氧烷基气体分离膜在分离过程中的机理和作用，对聚甲基硅氧烷基气体分离膜的未来研究方向进行了展望。     

有机硅基枝化高分子富氧膜材料

含有机硅侧基的高分子在富氧膜材料中占有重要位置，本文简要评述了ＰＴＭＳＰ、ＰＴＭＳＥ等含有机硅侧基富氧膜材料的性能及研究进展，讨论了有机硅基对富氧膜材料透气性能的影响。     

有机硅基枝化高分子富氧膜材料

含有机硅侧基的高分子在富氧膜材料中占有重要位置，本文简要评述了ＰＴＭＳＰ、ＰＴＭＳＥ等含有机硅侧基富氧膜材料的性能及研究进展，讨论了有机硅基对富氧膜材料透气性能的影响。     

三甲基硅基甲基纤维素的合成及膜的富氧性能

引言 在分离膜研究与发展的历史上,天然高分子是最早使用和进行改性的膜材料.纤维素及其衍生物具有原料丰富易得、成本低、无污染、成膜性好等优点,至今仍作为常用的膜分离材料[1].由于纤维素中存在大量的羟基和强的分子间氢键,氧透过性能并不理想,因此很少将纤维素直接用作气体分离尤其是氧氮分离的膜材料.近来,有专利报道对纤维素进行改性修饰,在羟基上连上含硅的基团如三甲基硅基,可以获得好的富氧性能[2].但由于该反应属于非均相反应,这一制备方法的实施和验证有困难.本文选用能够溶于有机溶剂的甲基纤维素(MC)为原料,以六甲基二硅胺烷(HMDS)作为三甲基硅基化试剂,通过均相反应很容易地制备了具有较高的取代度和良好的有机溶剂溶解性能的三甲基硅基甲基纤维素(TMS-MC).经溶液浇铸成膜,对其富氧性能研究后发现,与甲基纤维素膜相比,该膜的透氧系数和氧氮分离系数分别得到显著改善.     

超高性能富氧膜

本文对超高性能富氧膜的成膜工艺、富氧机理、富氧性能及应用前景作了较详细的评述,指出了急待解决的问题。     

富氧膜技术的进展

本文介绍了近年来富氧膜技术在化工、医用等领域的应用,简介了富氧膜的制备方法和分离机理,探讨了目前膜材料所存在的问题,并提出发展趋势。     

富氧膜性能测试新方法

本文建立了一种富氧膜富氧性能测试新方法——恒压空气容量分析法——本法可同时测定富氧空气流量、氧气含量、氧气及氮气透过率、氧氮分离系数等参数。它为膜材料的设计、工艺参数的选择提供了一种方便快速的研究手段。     

改性聚苯胺膜的气体分离性能及应用

论述了改性聚苯胺膜的气体透过性能。提出环取代聚苯胺膜由于自由体积增加而具有较大的透气系数。聚苯胺与聚酰亚胺预聚体的共混膜显示了比聚酰亚胺膜和聚苯胺膜更大的渗透系数，而分离系数介于二者之间。苯胺共聚物与乙基纤维素共混膜应用于空气分离，能将空气中氧体积分数从21％提高到46％，且具有中等的富氧空气流量和很好的稳定性，在医疗保健等领域具有很大的应用潜力。     

气体分离膜材料研究进展

介绍了高分子材料、无机材料、有机－无机杂化材料三类气体分离膜材料，主要包括聚酰亚胺、聚砜、聚二甲基硅氧烷、聚[1-(三甲基硅氧烷）－1－丙炔]等高分子材料，以及致密无机膜和多孔无机膜材料，并且对有机－无机杂化材料作了简要概述。在评价了各种膜材料性能的基础上，展望了气体分离膜材料的发展前景。     

高分子分离膜的研制与应用

介绍了聚砜超滤膜、纳滤膜、聚乙烯醇膜、中空纤维富氧复合膜等的合成与研究进展，并对各种膜的应用、现状与发展进行了阐述。     

膜法富氧技术及其应用研究

介绍了作者在膜法富氧技术方面的研究进展，并将膜法与其他制氧方法进行了比较，最后讨论了膜法富氧技术目前的有关应用，着重研究了膜法富氧在有色金属冶炼，硅酸盐窑炉，化铁炉，加热炉，医疗保健和柴油机增氧等方面的典型应用。     

梭式窑中二甲醚富氧燃烧的研究初探

本研究对梭式窑中二甲醚的富氧燃烧进行研究初探。结果表明,虽然二甲醚热值比液化气低,但由于二甲醚自身含氧,在燃烧过程中所需空气远低于液化气,因此二甲醚理论燃烧温度高于液化石油气。当二甲醚采用富氧燃烧后,火焰温度急速上升,富氧浓度可降低。当氧体积分数为27%～29%时,二甲醚烧成节能效果最佳。通过富氧燃烧帮助解决二甲醚燃烧过程中有机污染物的问题,有利于二甲醚在陶瓷工业的应用,并对二甲醚富氧燃烧技术在陶瓷窑炉的应用进行经济效益分析。     

Preparation and high oxygen‐enriching properties of cross‐linking polydimethylsiloxane/SiO2 nanocomposite membranes for air purification

Nanocomposite membrane based on polydimethylsiloxane (PDMS) and nanoscale SiO₂ particles were prepared by a convenient and mild sol–gel copolymerization of tetraethoxysilane as well as cross‐linking reaction. The oxygen‐enriching properties of cross‐linking PDMS/SiO₂ nanocomposite membranes containing different silica conversion and SiO₂ contents were investigated. The results showed that the nanocomposite membranes exhibited good membrane‐forming ability, superior mechanical properties, and high solvent resistance as well as excellent oxygen‐enriching properties for air purification. The oxygen‐enriching performance was regulated by the organic/inorganic ratio and silica conversion in the sol–gel synthesis process. Permeability and selectivity could increase simultaneously with the addition of nanoscale SiO₂. The oxygen permeation coefficient of the nanocomposite membrane increased to 680 Barrer and oxygen/nitrogen separation factor kept 3.0 or so, both higher than those of the corresponding pure PDMS membrane. The high oxygen‐enriching properties of the nanocomposite membranes arose from the introduction of SiO₂ particles, the sol–gel copolymerization, and cross‐linking method. © 2012 American Institute of Chemical Engineers AIChE J, 59: 650–655, 2013     

Permeability of synthetic poly(α-amino acid) membranes to oxygen dissolved in water

Membranes of synthetic poly(α-amino acids), namely, poly(γ-methyl L -glutamate) (PMLG), poly(γ-benzyl L -glutamate) (PBLG), poly(L -glutamic acid) (PLGA), poly(L -methionine) (PLM), and poly(N^?-carbobenzoxy-L -lysine) (PCLL), were prepared and their permeabilities of oxygen dissolved in water were measured in the 8–50°C temperature range using an oxygen electrode. Permeation curves for the poly(α-amino acid) membranes did not approach steady-state currents because of membrane degradation. To eliminate this, the membranes were laminated between polystyrene membranes; thus, the poly(α-amino acid) membranes came in direct contact with neither cathode surface nor electrolyte solution. No effect of membrane thickness on the permeability was observed. The Arrhenius plots of permeability coefficients for PCLL appear to change slope at about 22°C. This is consistent with the diffusion of oxygen in PCLL through the side-chain regions between helices. Comparisons between the permeability of oxygen dissolved in water and permeability of gaseous oxygen obtained by the high-vacuum method and between the activation energy of permeation of dissolved oxygen and that of gaseous oxygen were made in order to elucidate the effect of water on the oxygen permeation of each polymer. The permeability of the poly(α-amino acid) membranes to dissolved oxygen appears to depend on the properties of the side chains of the polymers.     

PDMS—PSF复合膜空分过程压力的影响

采用L-S相转化法制备了聚砜（PSF）非对称膜，在其表面涂覆硅橡胶（PDMS）制备PDMS-PSF复合膜，进行空分富氧实验。实验结果表明：在室温、操作压力为0．6MPa的测试条件下，富氧浓度最高可达40．4％，相应的渗透通量为0．43×10^-10（m^3／m^2·s·Pa）。同时系统考察了操作压力对复合膜的富氧分离性能的影响，对气体在PDMS—PSF复合膜中渗透行为的压力相关性进行了定性分析。     

环己烷富氧氧化制环己酮的研究

研究了环己烷富氧氧化的特征,考察了进气氧浓度的提高对反应速度、选择性、安全性和经济性的影响。通过工业化试验,控制氧气体积分数30%,反应温度160～175℃,压力1.0～1.2MPa,环己烷氧化转化率为3%～4%,能很好实现富氧氧化反应,氧化尾气的氧气体积分数可以安全控制在2%～3%。环己烷富氧氧化可用于环己酮装置的改扩建,较空气氧化经济性好。     

Air Separation through Modified Ethyl Cellulose Thin Film Supported on Porous Polyethersulfone

Abstract

Composite membranes for air separation were prepared from a liquid crystal DYC-modified ethyl cellulose (EC) thin film ranging in thickness from 1 to 7 μm and a porous polyethersulfone support with a thickness of 120 μm. The effects of DYC/EC (9/91) solution concentration, water, and operating parameters such as temperature, pressure, and time on the air-separation properties of the composite membranes were examined by a constant pressure—variable volume method. The permeate flux and oxygen concentration of the oxygen-enriched air (OEA) through the membranes increase significantly with increasing operating pressure difference. With decreasing casting solution concentration, or with increasing humidity around the membranes or operating temperature, the OEA flux increases greatly while the oxygen concentration sometimes decrease slightly. An increase in the operating time leads to an OEA flux decline, but the oxygen concentration rose when the operating time was varied for 70 hours. However, a further increase of the operating time from 70 to 500 hours does not lead to further changes of the OEA flux and oxygen concentrations. A thin-film composite membrane exhibits a slightly lower oxygen concentration accompanied by a very significant enhancement in the OEA flux and membrane stability compared to a homogeneous dense membrane of the same materials.     

Synthesis of silicalite-poly(furfuryl alcohol) composite membranes for oxygen enrichment from air

ABSTRACT: Silicalite-poly(furfuryl alcohol) [PFA] composite membranes were prepared by solution casting of silicalite-furfuryl alcohol [FA] suspension on a porous polysulfone substrate and subsequent in situ polymerization of FA. X-ray diffraction, nitrogen sorption, thermogravimetric analysis, scanning electron microscopy, and energy-dispersive X-ray spectroscopy were used to characterize silicalite nanocrystals and silicalite-PFA composite membranes. The silicalite-PFA composite membrane with 20 wt.% silicalite loading exhibits good oxygen/nitrogen selectivity (4.15) and high oxygen permeability (1,132.6 Barrers) at 50°C. Silicalite-PFA composite membranes are promising for the production of oxygen-enriched air for various applications.     

环己烷富氧氧化反应器内液相空间危险性分析

通过冷模实验对环己烷富氧氧化反应器内液相空间危险性进行分析,测试了液相空间气泡危险性。结果表明:环己烷富氧氧化(氧气体积分数大于30.0%)反应时,液相气泡的危险性比空气氧化的危险性大;在空气氧化和富氧氧化(氧气体积分数小于50.4%)工艺条件下,均未观察到气泡经点火后引起反应器体系内压力升高的现象,液相气体内反应均无燃爆危险。     

Dehydration of water–alcohol mixtures by vapor permeation through PVA/clay nanocomposite membrane

An organic/inorganic hybrid nanocomposite membrane, poly(vinyl alcohol)/clay (PVAC), was prepared. The morphology of PVAC nanocomposite membranes were characterized using transmission electron microscopy (TEM), X‐ray diffraction (XRD), and atomic force microscopy (AFM). The crystallinity and surface roughness increases with an increasing clay content in the PVAC nanocomposite membrane. Compared with the pure poly(vinyl alcohol) (PVA) membrane, the hybrid nanocomposite membrane (PVAC) shows an improvement in the thermal stability and the prevention of the water‐soluble property. The oxygen permeability and the water‐vapor permeation rate decreases with an increasing clay content (1–3 wt %) in the PVAC nanocomposite membranes. In addition, the effects of the clay content on the vapor‐permeation performance of an aqueous ethanol solution through the PVAC nanocomposite membranes was also investigated. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 3632–3638, 2003