有机/无机杂化渗透汽化优先透醇膜研究进展

渗透汽化优先透醇膜分离技术可有效解决燃料乙醇和丁醇生产中发酵产率较低的瓶颈问题,受到广泛关注。膜材料的选择与改性以及膜结构的构建是提高透醇性能的关键。有机/无机杂化膜可以实现有机和无机材料的优势互补,被认为是未来分离膜领域最重要的发展方向之一。本文扼要回顾了用于优先透醇渗透汽化分离的有机无机杂化材料,结合本文作者课题组的研究工作,重点阐述了杂化粒子的结构、粒径、界面相容性、纳微分散、负载量等因素对渗透汽化传递过程的作用机制,进一步对近年来发展的成膜新方法进行了总结。在此基础上,提出今后有机/无机杂化渗透汽化优先透醇膜研究的主要方向是发展新型纳米级、超疏水并与有机聚合物具有高度界面相容性的无机粒子,以及构建高负载量的纳微结构与超亲醇表面。     

生物乙醇提浓工艺中渗透蒸发膜材料的研究进展

渗透蒸发膜分离技术具有分离效率高、低能耗、易于和发酵装置耦合等优势,在生物乙醇的分离、提浓工艺中得到广泛应用。结合国内外生物乙醇的研究现状,综述了渗透蒸发膜分离技术的研究进展,并对渗透蒸发膜分离技术的核心材料--膜材料的制备与应用进行详细介绍,展望了生物乙醇的渗透蒸发膜分离技术的发展前景。     

利用蒸汽渗透技术实现发酵过程中乙醇的原位分离

正吉林石化研究院和北京化工大学合作承担的利用蒸汽渗透技术实现生物质燃料乙醇的原位发酵-分离过程研究项目通过了中国石油科技管理部组织的专家验收。采用该项目成果建设的乙醇发酵-蒸汽渗透耦合中试装置评价表明:渗透液中乙醇浓度在340~480g/L,发酵液中乙醇浓度保持在54~66g/L,分离性能稳定,效果显著,各项指标均达到要求。该项目组在国内首次提出了一种利用蒸汽渗透技术原位分离乙醇的方法,将生物乙醇发酵过程与蒸汽渗透技术相     

γ-(2,3环氧丙氧)丙基三甲氧基硅烷改性壳聚糖渗透蒸发杂化膜的制备及乙醇脱水性能研究

通过γ-缩水甘油醚氧丙基三甲氧基硅(KH-560)对壳聚糖进行交联改性制备乙醇脱水渗透蒸发杂化膜.实验结果表明偶联剂的加入能有效提高壳聚糖膜的分离效果,随着偶联剂含量的增加,杂化膜的对水的选择性先增加后下降,在2％(质量分数)时有最好的选择性.膜的分离因子随着进料温度的增大而降低,随着乙醇浓度的增大而增大;通量随着进料温度的增大而增大,随着乙醇浓度增大而减小.硅烷偶联剂/壳聚糖杂化膜呈现出良好的渗透蒸发分离性能,当进料乙醇浓度为95％(质量分数),温度为35℃时,通量和分离因子分别为134g/(h·m2)和97214.     

生物乙醇原位分离技术的研究进展

生物乙醇是一种重要的可再生生物燃料,使用生物乙醇可大幅减少温室气体排放。为了建立更高效低能耗的生物乙醇回收工艺,原位分离（ISPR）技术应运而生。本文综述了近年来乙醇原位分离的研究进展,从原理及应用等进行多方面详细地介绍,包括气提、真空发酵、吸附、液-液萃取、渗透汽化、膜蒸馏等分离技术。针对分离性能、能耗成本等问题分析了不同分离技术耦合发酵过程的优势及不足,重点回顾了以渗透汽化为代表的膜分离技术,总结了渗透汽化膜材料的选择以及膜的制备方法,旨在提升乙醇分离膜性能优化乙醇分离工艺。为整合不同分离技术的特点及优势,聚焦多级耦合分离系统的开发对各级分离技术联用的性能及潜力进行剖析与评价,并在此基础上研判其发展前景。     

新型聚乙烯醇/硅系杂化膜的制备及渗透性能

采用溶胶-凝胶法制备了聚乙烯醇（PVA）/γ-氨丙基三乙氧基硅氧烷（APTEOS）有机/无机杂化膜。用FTIR和XRD对杂化膜进行了表征。测定了膜在乙醇/水溶液中的溶胀行为。考察了杂化膜对85%（质量）的乙醇/水溶液的渗透蒸发分离性能。加入APTEOS降低了PVA的结晶度,有效控制了膜的溶胀,呈现出优良的分离性能。随着APTEOS含量的增加,杂化膜的选择性急剧增加,在5.0%（质量）时达到最大值;同时膜的渗透通量迅速增加。解决了PVA膜trade-off效应。     

浓乳液聚合制备优先脱醇渗透蒸发分离膜

提出了一种以浓乳液聚合直接浇注制备新型有机硅类渗透蒸发分离膜的新方法。考察了乙醇浓度、分离时间与渗透蒸发分离性能之间的关系,表征了有机硅浓乳液聚合过程中的乳胶粒子形态与成膜后粒子堆砌的微观结构。结果表明,利用膜中乳胶粒子间微通道的极性效应可以有效地分离醇/水混合物中的醇,且优先脱醇效果明显,分离性能良好。在乙醇/水混合物的渗透蒸发膜分离实验中,其渗透通量为4.7～165g·m-2·h-1,分离因子为1.0～11.3,分离选择性最好时的料液中乙醇的质量分数为33.41%。     

发酵与分离技术结合的过程及其在乙醇生产中的应用

本文系统地介绍了超滤、溶剂萃取、膜蒸馏、超滤及反渗透、渗透蒸发和渗透牵引等分离技术与发酵过程结合的基本原理，重点介绍了这些技术在乙醇发酵中的应用及新进展。与分离技术结合的乙醇发酵过程的开发，为提高生产率、降低生产成本开辟了一条新途径，是一种很有应用前景的乙醇生产方法。     

蒸汽渗透技术在乙醇发酵原位分离耦合过程中的应用研究

利用5L发酵罐分别对乙醇流加发酵、分批发酵蒸汽渗透耦合过程和流加发酵蒸汽渗透耦合过程进行了研究,并对过程进行了优化。当发酵液中ρ(乙醇)70g/L时,乙醇产率明显减慢;相对于分批发酵,蒸汽渗透耦合可使乙醇产率提高25%;相对于流加发酵,蒸汽渗透耦合可使乙醇产率提高44%;发酵与蒸汽渗透耦合最佳料液体积与膜面积比V∶A=0.053m,一级冷凝温度为-20℃,在以上条件下,整个过程乙醇回收率可达92.80%,发酵与蒸汽渗透能够较好耦合。     

水—乙醇分离膜

介绍了渗透蒸发膜的发展历史及现状况的新型 简要阐述了分离膜的分离机理和特点,着重介绍了水－乙醇分离膜的材料,并对它们的性能特点进行了比较。     

A review of pervaporation for product recovery from biomass fermentation processes

Although several separation technologies are technically capable of removing volatile products from fermentation broths, distillation remains the dominant technology. This is especially true for the recovery of biofuels such as ethanol. In this paper, the status of an emerging membrane‐based technology, called pervaporation, for this application is reviewed. Several issues and research priorities which will impact the ability of pervaporation to be competitive for biofuel recovery from fermentation systems are identified and discussed. They include: increased energy efficiency; reduction of capital cost for pervaporation systems; longer term trials with actual fermentation broths; optimized integration of pervaporation with fermentor; synergy of performing both alcohol recovery and solvent dehydration by pervaporation with dephlegmation fractional condensation technology; and updated economic analyses of pervaporation at various biofuel production scales. Pervaporation is currently viable for biofuel recovery in a number of situations, but more widespread application will be possible when progress has been made on these issues. Published in 2005 for SCI by John Wiley & Sons, Ltd.     

Pervaporation and Vapor Permeation Tutorial: Membrane Processes for the Selective Separation of Liquid and Vapor Mixtures

Pervaporation and vapor permeation are membrane-based processes proposed as alternatives to conventional separation technologies. Applications range from organic solvent removal from water, ethanol, or butanol recovery from fermentation broths, solvent/biofuel dehydration to meet dryness specifications, and organic-organic separations such as the removal of sulfur compounds from gasoline. Unlike membrane filtration processes, which rely on an applied liquid pressure gradient and size sieving to accomplish a separation, pervaporation and vapor permeation separate compounds based on a chemical activity driving force and the sorption and diffusion of the compounds through the membrane. These properties enable the separation of even miscible liquid mixtures.     

A new hybrid membrane separation process for enhanced ethanol recovery: Process description and numerical studies

Ethanol is a biofuel, produced through the fermentation of sugars derived from biomass. Its usefulness as a fuel is limited by the energy intensive nature of the ethanol separation process. The ethanol recovery process is inefficient due to the dilute nature of the fermentation product and the presence of the ethanol?water azeotrope. This investigation presents a new hybrid separation process for energy efficient ethanol recovery. The new process is a hybrid of distillation and pervaporation. However, as opposed to most other hybrid processes, the distillation and pervaporation processes are combined into single unit. An overview of the proposed system was provided and differences to the conventional separation process were highlighted. A mathematical model was derived to explain the transport phenomena occurring in the hybrid process. The model was then used to compare the process to distillation. It was shown that the hybrid process is capable of breaking the ethanol-water azeotrope. It was also demonstrated that the pervaporation process, which is associated with both material and energy transfer, induces partial condensation of the vapor and thereby affects the efficiency of vapor?liquid contacting. Simulations were presented to show the impact of reflux ratio and pervaporation flux on the performance of the process.     

渗透汽化在生物燃料乙醇制备中的研究进展

渗透汽化作为一种新型的膜分离技术应用于发酵法制备生物燃料乙醇,不但能减少产物对微生物的抑制作用,而且可以脱水制备高纯度燃料乙醇,因而具有显著的优势。本文对渗透汽化在发酵法制备燃料乙醇中所涉及的膜材料、耦合工艺、应用现状和经济评价进行了详细的综述,并对发展趋势作了展望。     

Reliable production of highly concentrated bioethanol by a conjunction of pervaporation using a silicone rubber sheet‐covered silicalite membrane with adsorption process

For the production of highly concentrated bioethanol by pervaporation using an ethanol‐permselective silicalite membrane, pervaporation performance was investigated using a silicalite membrane entirely covered with a silicone rubber sheet to prevent direct contact with acidic compounds. By using a resistance model for membrane permeation, the separation factor of the covered silicalite membrane towards ethanol can be estimated from the individual pervaporation performances of the silicalite membrane and the silicone rubber sheet. No decrease in the ethanol concentration through the silicone rubber sheet‐covered membrane was caused when ethanol solutions containing succinic acid were supplied. By directly passing the permeate‐enriched ethanol vapor mixed with water vapor through a dehydration column packed with a molecular sieve of pore size 0.3 nm, highly concentrated bioethanol up to 97% (w/w), greater than the azeotropic point in the ethanol/water binary systems, can be obtained from 9% (w/w) fermentation broth. Copyright © 2004 Society of Chemical Industry     

ZIF-L/PDMS混合基质膜蒸气渗透耦合发酵强化乙醇生产效率的研究

蒸气渗透（VP）膜分离不存在膜污染风险,在生物乙醇生产中具有广阔的应用前景。将聚二甲基硅氧烷（PDMS）膜和以二维沸石咪唑骨架（ZIF-L）为填充基质制备的PDMS（ZIF-L/PDMS）混合基质膜,分别用于VP膜分离与菊粉水解液发酵制乙醇过程的耦合,分析了二者在耦合过程中的分离性能和发酵性能。探究了不同膜分离方式、不同类型膜及操作条件对膜分离性能的影响。实验结果表明,当料液浓度为5%（质量）、蒸气循环流量为1.5 L·min^-1时,ZIF-L/PDMS混合基质膜的VP性能高于渗透汽化（PV）,归一化总通量达到1148.78 g·m^-2·h^-1,分离因子高达19.14,显著提升了乙醇分离性能。ZIF-L/PDMS混合基质膜用于VP耦合发酵,实现了耦合过程的高渗透性和乙醇选择性,与文献报道相比,乙醇移除效果最优,乙醇产率和时空产率分别达到0.421 g·g^-1、3.07 g·L^-1·h^-1,两个指标明显高于单独发酵,极大地提高了乙醇生产效率。因此,ZIF-L/PDMS混合基质膜在原位分离发酵乙醇方面具有很大的应用潜力。     

Mass transfer model,preparation and applications of zeolite membranes for pervaporation dehydration:A review

Pervaporation (including vapor permeation) is a kind of new membrane separation technology, possessing the advantages of high efficiency, energy saving and convenient operation. It has promising application in the separation and purification of organic solvents. Dehydration is an important step in the production and recovery of organic solvents. Zeolite membranes have attracted wide attention for pervaporation dehydration due to their high separation performance and good thermal/chemical stability. So far, zeolite membranes have been preliminarily industrialized for dehydration of organic solvents. This paper reviews the recent development of zeolitemembranes for pervaporation dehydration, includingmass transfermodels, preparation and applications of zeolite membranes. The review also discusses the current industrial applications of zeolite membranes and their future development in pervaporation.     

Characteristics of permeation and separation of aqueous alcoholic solutions through a poly[bis(2,2,2-trifluoroethoxy)phosphazene] membrane by evapomeation and pervaporation

The characteristics of permeation and separation for aqueous solutions of methanol and ethanol through a poly[bis(2,2,2-trifluoroethoxy)phosphazene] (PBTFP) membrane were studied by pervaporation and evapomeation. In pervaporation technique, methanol was preferentially permeated in all of the feed solution compositions and ethanol was permeated in lower ethanol concentrations of the feed solution. Water was predominantly permeated from the feed solutions with higher ethanol concentration. In evapomeation technique, water was selectively permeated in both all of the feed vapor compositions for aqueous methanol and ethanol solutions. These different permselectivities depended on the feed composition and the membrane permeation technique and could be discussed by a difference in the mechanisms of permeation and separation. It was found that the permeation rate was influenced remarkably by the degree of swelling of the PBTFP membrane and the permselectivity for water of aqueous alcoholic solutions was enhanced by an increasing degree of swelling of the membrane. When the degree of swelling of the membrane with rising permeation temperature was small, both the permeation rate and permselectivity for alcohol in pervaporation and evapomeation increased with the permeation temperature. The above results are discussed considering the PBTFP membrane structure in evapomeation and pervaporation.