Preparation of zeolite-coated pervaporation membranes for the integration of reaction and separation

Pervaporation is a promising option to enhance conversion of reversible condensation reactions, generating water as a by-product. In this work, composite catalytic membranes for pervaporation-assisted esterification processes are prepared. Catalytic zeolite H-USY layers have been deposited on silica membranes by dip-coating using TEOS and Ludox AS-40 as binder material. Membrane pre-treatment and the addition of binder to the dip-coat suspension appear to be crucial in the process. Tuning of catalytic layer thickness is possible by varying the number of dip-coat steps. This procedure avoids failure of the coating due to the high stresses, which can occur in thicker coatings during firing. In the pervaporation-assisted esterification reaction the H-USY coated catalytic pervaporation membrane was able to couple catalytic activity and water removal. The catalytic activity is comparable to the activity of the bulk zeolite catalyst. The collected permeate consists mainly of water and the loss of acid, alcohol and ester through the membrane is negligible. The performance of the membrane reactor is mainly limited by reaction kinetics and can be improved by using a more active catalyst.     

微波合成的NaA型分子筛膜在乙醇脱水中试及3万吨/年工业示范装置的蒸汽渗透性能研究

设计并搭建了分子筛膜脱水中试装置,对本课题组微波加热技术合成的工业级NaA型分子筛膜进行乙醇/水体系蒸汽渗透的性能研究,得到了NaA型分子筛膜的水渗透通量方程,水透量与原料液含水量、雷诺数之间的关系及变化规律。对精馏与膜分离耦合工艺进行流程模拟,提出了精馏与膜分离的最佳耦合点,并且给出了分子筛膜的价格和寿命对总费用的影响,为NaA型分子筛膜工业应用提供重要参考依据。根据中试结果,在江苏索普集团醋酸加氢制乙醇项目中建设完成了3万吨/年的分子筛膜乙醇脱水装置,是目前国内单套最大的分子筛膜脱水装置。目前,装置已连续运行超过1000h,运行结果良好。     

Facile method towards functionalization of partially fluorinated polyarylethers via sequential post-polymerization modification

A novel partially fluorinated arylene vinylene ether (FAVE) polymer containing ester groups was synthesized, which was used to prepare three reactive FAVE polymers containing carboxylic acid groups, alcohol groups, and acid chloride groups, respectively. Post-polymerization modifications of the FAVE polymer's carboxylic acid groups (via a DCC coupling procedure with the desired alcohol), alcohol groups (via DCC coupling or an acid chloride esterification procedure with the desired carboxylic acid or acid chloride), and acid chloride groups (via an optimized nucleophilic substitution reaction with the desired alcohol or amine) were successfully performed. Several examples have been successfully prepared to demonstrate the versatility of these developed modification methods. FAVE polymers have been prepared with NHS active ester groups, Disperse Red 1 chromophores, benzyl bromide groups, aryl trifluorovinyl ether groups, ATRP initiator groups, vinyl groups, propargyl groups, Disperse Orange 3 chromophores, and benzaldehyde groups. In most cases, analytical data are consistent with a quantitative conversion of the reactive or functional groups. It is demonstrated that no degradation of the FAVE polymer matrix occurs after multistep post-polymerization modification reactions.     

香豆素-3-羧酸及酯合成方法的研究

在无水乙醇中,以二乙胺为催化剂,通过水杨醛与丙二酸二乙酯的Knoevenagel缩合反应合成了香豆素-3-羧酸乙酯,再经水解、酸化得到香豆索-3-羧酸。对影响香豆素-3-羧酸乙酯收率的原料配比、催化剂的用量进行了研究。所得最佳合成条件为：水杨醛与丙二酸二乙酯物质的量比1：1．2,二乙胺与水杨醛物质的量比为1：4,反应时间2h,在最佳工艺条件下。香豆素-3-羧酸乙酯的收率85％,香豆素-3-羧酸的收率95％。     

二次水热合成法制备ZSM-5分子筛膜及其渗透汽化性能

采用二次水热合成法在管状多孔莫来石支撑体上制备高耐酸性ZSM-5分子筛膜,系统地研究分子筛晶种和合成溶胶中H₂O/SiO₂摩尔比率对ZSM-5分子筛膜生长与渗透汽化性能的影响,采用X射线衍射、冷场扫描电子显微镜和电子能谱等表征技术分别对制备的ZSM-5分子筛及其ZSM-5分子筛膜的结构、形貌和Si/Al比进行表征。针对分离75℃、90% HAc/H₂O的水溶液,最优化条件下制备的ZSM-5分子筛膜表现出优良的渗透汽化性能,渗透通量和分离因子分别为0.98kg/(m²·h)和890。此外,本研究所采用制备耐酸性ZSM-5分子筛膜的方法表现出良好的重现性,重复制备的12根ZSM-5分子筛膜在75℃下分离90% HAc/H₂O的水溶液时,平均通量和分离系数分别为（0.85±0.15）kg/(m²·h)和650±290。再者,ZSM-5分子筛膜在45～75℃的温度范围内分离50%～95% HAc/H₂O水溶液时都表现出优良的渗透汽化性能。     

Formation of five-membered cyclic anhydride intermediates by polycarboxylic acids: Thermal analysis and Fourier transform infrared spectroscopy

Butanetetracarboxylic acid (BTCA) has been used as the most effective nonformaldehyde crosslinking agent for cotton and wood pulp cellulose. Our previous research has indicated that a polycarboxylic acid esterifies cellulose in two steps: the formation of a five-membered cyclic anhydride intermediate by the dehydration of two adjacent carboxyl groups, and the reaction between cellulose and the anhydride intermediate to form an ester linkage. In this research, we investigated the formation of carboxylic anhydrides by BTCA and other polycarboxylic acids in powder forms, and as finishes applied to cotton fabric using thermal gravimetry, differential scanning calorimetry, and Fourier transform infrared spectroscopy. We found that BTCA and other polycarboxylic acids in powder forms start to form five-membered cyclic carboxylic anhydrides when the temperature reaches the vicinity of their melting points. The formation of carboxylic anhydride is accelerated above the melting points. We also found that BTCA forms anhydrides at lower temperatures when it is applied to cotton fabric as a finish. An increase in temperature increases both the amount of anhydride and the amount of ester formed on the cotton fabric. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 70: 2711–2718, 1998     

4-[2''-(反式-4"-正丙基环己基)乙基]环己酮的合成

以反式-4-正丙基环己基甲酸和4-羰基环己基甲酸乙酯为原料,通过羧酸还原、溴代反应、羰基保护、酯还原、格氏反应、水解、醇脱水、加氢等8步反应合成了乙烷类液晶中间体4-[2’-(反式-4"-正丙基环己基)乙基]环己酮,熔点34.56℃。并用气相-质谱(GC-MS)、红外光谱(IR)、核磁共振氢谱(1H NMR)确认了结构。     

4-[2’-（反式-4”-正丙基环己基）乙基]环己酮的合成

以反式-4-正丙基环己基甲酸和4-羰基环己基甲酸乙酯为原料,通过羧酸还原、溴代反应、羰基保护、醑还原、格氏反应、水解、醇脱水、加氢等8步反应合成了乙烷类液晶中间体4-[2’-（反式-4”-正丙基环己基）乙基]环己酮,熔点34.56℃。并用气相-质谱（GC-MS）、红外光谱（IR）、核磁共振氢谱（^1H NMR）确认了结构。     

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.     

Characterization of estolides produced from the acid-catalyzed condensation of oleic acid

Estolides produced from an acid-catalyzed condensation of oleic acid were characterized by high-performance liquid chromatography (HPLC), gas chromatography (GC), GC-mass spectrometry (MS) and nuclear magnetic resonance (NMR). C-8 reverse-phase HPLC provided a clean resolution of the estolide oligomers present in the reaction mixtures, allowing an average oligomier distribution to be calculated. Corroboration of HPLC results were obtained either through hydrolysis of the estolide mixture and quantitation of the hydroxy fatty acid content by GC, through the integration of the α-methylene protons adjacent to the carbonyl of the acids vs. the esterns in the¹H NMR spectrum, or by titration of the carboxylic acid with standardized base. GC and GC-MS analysis of the hydrolyzed estolide mixture indicated that the ester position were centered around the original double-bond position, with linkages ranging from positions 5–13. Likewise, the unsaturation was distributed along the fatty acid backbone.     

Mechanism of crosslinking of papers with polyfunctional carboxylic acids

Brief thermal curing of papers treated with an aqueous solution of polyfunctional carboxylic acids and NaH₂PO₄ imparts substantial wet strength to the papers. The effectiveness of such carboxylic acids increases with their functionality in the order 1,2,3,4-butanetetracarboxylic acid (BTCA) > tricarballylic acid (TCA) ? succinic acid. The two main stages of the curing reaction of papers, i.e., pendant attachment of the polyfunctional carboxylic acids via esterification with cellulosic hydroxyl groups, and its further reaction with another cellulose hydroxyl group producing crosslinks of the cellulose fibers were analyzed separately using a combination of acid-base and conductometric titrations. The extent of reaction of the polyfunctional carboxylic acids with paper was followed by pH titration, which shows the total decrease in acid functions as the curing progresses and is directly related to the total consumption of carboxylic acids groups by ester attachment and ester crosslinking steps. The conductometric titration, on the other hand, measures the increase in carboxylic acids bound to cellulose units of the paper as a direct result of previous esterification steps. Our studies reveal that the reaction of BTCA with papers is essentially quantitative after 15 min of curing. The amount of once-reacted BTCA increases in the initial phases of the curing reaction and then decreases as more and more carboxylic acid units are converted into crosslinking sites, while the amount of crosslinked BTCA increases throughout the curing reaction. The reaction profile of papers with TCA differs from that of BTCA in that the curing reaction is initially dominated by the formation of ester appendages; crosslinking becomes the main reaction only after extended curing times. We attribute this difference to the ability of BTCA to form an highly reactive difunctional crosslinking reagent at the outset of the curing reaction, while TCA is initially monofunctional in its reaction with cellulosic hydroxyl groups (formation of a monoanhydride). The relationship between the wet tensile strength of the treated papers and their degree of crosslinking is also discussed. © 1995 John Wiley & Sons, Inc.     

Separation of water–isopropyl alcohol mixtures with novel hybrid composite membranes

New‐fangled hybrid composite membranes were prepared by the incorporation of 5, 10, and 15 mass % NaY–zeolite particles into blend membranes of carboxymethyl cellulose (CMC)‐g‐acrylamide/sodium alginate (NaAlg) and crosslinked with glutaraldehyde. The pervaporation (PV) separation performance of the hybrid composite membranes was explored for the dehydration of isopropyl alcohol from their aqueous solutions at 30°C. The effect of NaY–zeolite in these blend membranes was investigated in PV dehydration. From the experimental results, we found that NaY particles could be intercalated in the aqueous polymer solution. The obtained results show that both the flux and selectivity increased simultaneously with increasing zeolite content in the membrane. This was explained on the basis of an enhancement of the hydrophilicity, selective adsorption, and molecular sieving action by the creation of pores in the membrane matrix. The membranes were characterized by differential scanning calorimetry, scanning electron microscopy, and Fourier transform infrared spectroscopy. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2012     

Synthesis of poly(ester sulfoimide) from dichlorocarbonylimide of disaccharindicarboxylic acid and aromatic diols

A new chlorocarbonylimide of disaccharindicarboxylic acid was synthesized by condensation of imides of saccharin‐6‐carboxylic acid with alkyl‐ and alkylaryl bishalogenides. Poly(ester sulfoimide), soluble in organic solvents, was synthesized by polycondensation of chlorocarbonylimide with bisphenol. DTA and TGA investigations have shown that poly(ester sulfoimide)s were stable at temperatures up to 300°C–345°C. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1687–1691, 2006     

Enhanced production of hydroxymethylfurfural from fructose with solid acid catalysts by simple water removal methods

This paper demonstrates two simple ways to increase 5-hydroxymethylfurfural (HMF) yield (selectivity) in fructose dehydration with various solid acid catalysts. One is a water removal from the reaction mixture by a mild evacuation at 0.97 × 10⁵ Pa; it increases HMF yield for various catalysts (heteropoly acid, zeolite, and acidic resin). The removal of water suppresses two undesired reactions: the hydrolysis of HMF to levulinic acid and the reaction of partially dehydrated intermediates to condensation products. The other method is a decrease in the particle (bead) size of the resin (Amberlyst-15). The crushed and sieved Amberlyst-15 powder in a size of 0.15–0.053 mm shows 100% HMF yield at high fructose concentration (50 wt.% in DMSO), which is to our knowledge the highest yield to date. Near-infrared spectroscopic characterization of adsorbed water suggests that the enhanced yield can be caused by an improved removal of adsorbed water in a small-size resin particle.     

渗透汽化脱水技术及其在酯化工业中的应用

渗透汽化是分离某一液体物质含量较低的液体混合物的实用分离方法.高性能渗透汽化膜的开发、膜组件及系统的合理设计是实现膜技术工业化的两个关键因素.分析了渗透汽化膜用于酯化工业耦合脱水工艺的研究现状,展望渗透汽化膜在制备乳酸酯的酯化反应、双酚A的缩合反应和手性化合物的酯合成反应等方面的应用前景.     

Paper wet performance and ester crosslinking of wood pulp cellulose by poly(carboxylic acid)s

Poly(carboxylic acid)s have been used as crosslinking agents for wood pulp cellulose to increase the wet strength of paper. In this research, we evaluated the effects of two multifunctional carboxylic acids, i.e., 1,2,3,4-butanetetracarboxylic acid (BTCA) and poly(maleic acid) (PMA), on the wet strength retention, dimensional stability, wet stiffness, and folding endurance of the treated paper. We observed that the wet strength retention, dimensional stability, and wet stiffness of the treated sheets increase, whereas the folding endurance decreases as the poly(carboxylic acid) concentration applied to those sheets increases. We measured the ester carbonyl band absorbance in the spectra of the treated paper. The linear correlation between the ester carbonyl band absorbance and wet strength, dimensional stability, and wet stiffness indicates that the improvement in the wet performance of the treated paper is directly attributed to the ester crosslinking of the wood pulp cellulose by poly(carboxylic acid)s. The data presented in this article also indicate that FTIR spectroscopy can be used for predicting the performance of the paper crosslinked by poly(carboxylic acid)s. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67: 649–658, 1998     

Separation of Ethylene Glycol/Water Mixtures using NaA Zeolite Membranes

Inorganic membranes and particularly zeolite membranes are usually used for the dehydration of organic solvents by pervaporation (PV). This work reports an experimental study on the PV dehydration of ethylene glycol (EG)/water mixtures using commercial nanoporous NaA zeolite membranes. The concentration range investigated (C_EG > 70 wt %) was selected according to existing industrial requirements. The recirculation flow rate was kept at a value of 1.5 L/min. The fluxes and separation factors were monitored as the dehydration proceeded. In addition, the activation energy of permeation (E_a) was calculated. The effect of temperature was investigated in the range 50–70 °C. The results obtained demonstrated the successful performance of the membrane for the dehydration of EG/water mixtures. It was observed that at 70 °C and with 70 wt % initial EG concentration, larger fluxes and separation factors could be obtained, i.e., 0.94 kg m^–2h^–1 and 1177, respectively. The Pervaporation Separation Index (PSI) of the membrane was found to be high compared to that of polymeric membranes.     

分子筛膜渗透蒸发技术研究进展

概述了渗透蒸发膜分离过程和分子筛膜的优点,重点综述了沸石分子筛膜在渗透蒸发中的传输机理和传质模型,以及温度、压力、组成等对渗透蒸发膜分离性能的影响因素,介绍了分子筛膜渗透蒸发技术在有机溶剂脱水、水中脱除有机物和有机混合物分离等方面的应用,展望了分子筛膜在渗透蒸发膜分离技术中的发展方向。     

Mixed matrix membranes of H‐ZSM5‐loaded poly(vinyl alcohol) used in pervaporation dehydration of alcohols: Influence of silica/alumina ratio

Mixed matrix membranes of poly(vinyl alcohol) loaded with zeolite particles having different silica alumina ratio were prepared and used in the pervaporation dehydration of ethanol and isopropanol (IPA) from their aqueous mixtures. The membranes were characterized by physicochemical techniques that revealed higher interaction between polymer and zeolite particles having higher alumina than those with lower alumina in the zeolite framework. Both, membrane selectivity to water and flux were increased as the alumina content in the zeolite increases. Separation factors of zeolite with lower alumina incorporated membranes were, respectively, 236 and 334 for the feed mixture compositions of 4 wt% water in ethanol and 10 wt% water in IPA at 30°C. On the other hand, membranes containing zeolites with higher alumina content showed slightly higher separation factors of 349 and 568, respectively, for the same feed mixtures at 30°C. Such an incremental improvement in membrane performance with increase in alumina content in the zeolite framework is attributed to favorable interaction between zeolite particles and the polymer matrix. POLYM. ENG. SCI., 54:1774–1782, 2014. © 2013 Society of Plastics Engineers     

高含量全反式番茄红素的全合成方法研究

设计了番茄红素的全合成绿色新工艺,采用弱碱性交换树脂催化醛酮缩合,用格氏试剂诱导制备六碳醇,与亚磷酸三乙酯发生Wittig-Horner反应制备六碳膦酸酯,再以甲基庚烯酮为起始原料,经Darzen反应与六碳膦酸酯缩合,经过格氏,催化氢化,脱水,手性拆分制备全反式十五碳磷酸酯,与十碳双醛对接,得高含量全反式番茄红素。