Pervaporation membrane reactor study for the esterification of acetic acid and isobutanol using polydimethylsiloxane membrane

In this study, isobutyl acetate, a valuable solvent in cosmetics, aroma and paint industries, is produced by pervaporation–esterification equilibrium reaction in a batch pervaporation membrane reactor (PVMR) using homogeneous (sulphuric acid) and heterogeneous (Dowex 50W-X8) catalysts. The effects of catalyst loading, catalyst type, reaction time, membrane thickness, temperature and initial molar ratio of reactants were investigated. A cross-linked polydimethylsiloxane (PDMS) membrane selective to esters was prepared and used in PVMR. Batch reactions were carried out also in a simple batch reactor (SBR) without pervaporation under the same conditions to compare the conversions for the reactions with and without pervaporation. In conclusion, PVMR experiments showed that the PDMS membrane can be used to remove the isobutyl acetate formed selectively with acceptable conversions and pervaporation fluxes.     

阳离子交换树脂催化合成乳酸异丁酯的研究

以阳离子交换树脂为催化剂,研究了乳酸与异丁醇合成乳酸异丁酯的反应,结果表明：用1．0g阳离子交换树脂作催化剂,对0．1mol(9g)乳酸,当乳酸与异丁醇的摩尔比为1：2,在回流条件下反应3h,酯产率可达87．1％,方法具有催化活性较高,对设备无腐蚀、三废排放少,催化剂可重复使用多次等特点。     

酯化反应耦联渗透汽化膜过程对平衡移动的影响

以乙酸正丁酯的合成为目标反应,系统地考察了渗透汽化－ 酯化反应耦联复合膜反应器中过程因素（进料中醇、酸摩尔比率、膜面积与反应混合物体积的比值、复合膜渗透通量的大小,反应、分离温度等）对酯化反应化学平衡移动的影响。实验发现反应（分离）温度是影响酯化反应化学平衡移动的最重要因素。     

Pervaporation‐Assisted Esterification of Caproic Acid with Isobutanol in Conventional,In Situ,and Ex Situ Reactors

The factors that affect the pervaporation‐assisted esterification of caproic acid and isobutanol have been investigated in a batch reactor and compared with two different pervaporation reactors, in situ and ex situ reactors, with different configurations. The operating process parameters of the pervaporation modules can be adjusted to optimize the performance, which improves the conversion of reactants and reduces the operating costs. The performances of the reactors have been extensively studied and the membrane selectivity has been investigated in terms of the flux of individual reaction species. The mass transfer limitation of both pervaporation reactors was studied and suitably eliminated. In addition, the performance of the pervaporation reactors was investigated by evaluating the ratio of water removal rate to the water production rate.     

无机固体酸催化合成苯乙酸异丁酯

应用一水硫酸氢钠催化苯乙酸和异丁醇的酯化反应，合成了苯乙酸异丁酯，研究结果表明，硫酸氢钠具有较高的催化活性，考察了苯乙酸／异丁醇摩尔比，催化剂用量及反应时间对酯产率的影响，在典型反应条件（苯乙酸／异丁醇／硫酸氢钠的摩尔比＝1：4：0．036，回流分水2h)下，所得苯乙酸异丁酯的产率达92．7％，该催化剂易于回收且可重复使用。     

活性炭负载对甲苯磺酸催化合成苯甲酸异丁酯

以活性炭负载对甲苯磺酸为非均相催化剂,异丁醇为共沸带水剂,对苯甲酸与异丁醇之间的酯化反应进行了研究,重点考察了醇酸摩尔比、催化剂用量、反应时间对苯甲酸异丁酯收率的影响。实验结果表明,活性炭负载对甲苯磺酸有着良好的催化活性,当苯甲酸的加入量为0.1 mol,醇酸摩尔比为3.0,催化剂用量为反应物总质量的4.0%,回流反应2.5 h时,苯甲酸异丁酯收率可达90%以上,且催化剂重复使用5次仍保持较高活性。     

硫酸镓催化合成对羟基苯甲酸异丁酯

采用硫酸镓为催化剂合成了食用防腐剂对羟基苯甲酸异丁酯。考察了催化剂用量、醇酸物质的量比、反应时间、带水剂种类及用量等因素对产物收率的影响。结果表明,硫酸镓具有催化活性高,易分离回收,操作简单,后处理方便等优势。硫酸镓是合成对羟基苯甲酸异丁酯高效、经济且环境友好的催化剂,有一定工业化应用前景。适宜反应条件为:对羟基苯甲酸0.05 mol,醇酸物质的量比6,催化剂2.0 g,甲苯10 mL,反应时间8 h,产物收率达96.6%。     

Effect of water on HDS of DBT over a dispersed Mo catalyst using in situ generated hydrogen

A novel process was developed for the bitumen emulsion upgrading, wherein emulsion breaking and upgrading occurred in the same reactor using H₂ generated in situ from the water in the emulsion via the water gas shift reaction (WGSR). In this study, dibenzothiophene (DBT) was chosen as a model compound to investigate the effect of water and in situ H₂ on hydrodesulfurization (HDS). All the experiments were performed in a 1-L autoclave reactor at temperatures between 300 and 380 °C using in situ H₂ and ex situ H₂ (externally supplied H₂) over a dispersed Mo catalyst formed from phosphomolybdic acid (PMA). At very low water content, water was found to promote the HDS reaction in the ex situ H₂ run probably because it facilitates the formation of more active dispersed MoS_x species. At higher water content, however, water inhibits every individual reaction in the reaction network in the HDS of DBT, blocking the hydrogenation pathway more than the hydrogenolysis pathway. The relative reactivity of the in situ and ex situ H₂ depends on the water content present in the reaction system. At an optimized mole ratio of H₂O:CO (1.35), higher HDS activity was observed in the in situ H₂ run compared to ex situ H₂ run, and particularly, the hydrogenation pathway was promoted in the in situ H₂ run.     

油酸异丁酯的合成及其对生物柴油降凝效果研究

油酸与异丁醇在离子液体催化剂的作用下发生酯化反应制备油酸异丁酯。研究了催化剂用量、醇酸配比、反应时间、反应温度等对酯化反应转化率的影响,并通过测定凝固点、冷滤点、粘度来考察脂肪酸异丁酯对生物柴油的降凝效果。结果表明,当催化剂用量为2%,醇酸体积比2∶1(摩尔比6.8∶1),反应温度100℃,反应时间3 h,转化率达到95.6%。降凝实验结果表明,把一定量的脂肪酸异丁酯添加到生物柴油中可有效地降低生物柴油的凝固点、冷滤点,改善其低温流动性能。     

Co‐current and Countercurrent Configurations for a Membrane Dual Type Methanol Reactor

A dynamic model for a membrane dual‐type methanol reactor was developed in the presence of catalyst deactivation. This reactor is a shell and tube type where the first reactor is cooled with cooling water and the second one with feed synthesis gas. In this reactor system, the wall of the tubes in the gas‐cooled reactor is covered with a palladium‐silver membrane which is only permeable to hydrogen. Hydrogen can penetrate from the feed synthesis gas side into the reaction side due to the hydrogen partial pressure driving force. Hydrogen permeation through the membrane shifts the reaction towards the product side according to the thermodynamic equilibrium. Moreover, the performance of the reactor was investigated when the reaction gas side and feed gas side streams are continuously either co‐current or countercurrent. Comparison between co‐current and countercurrent mode in terms of temperature, activity, methanol production rate as well as permeation rate of hydrogen through the membrane shows that the reactor in co‐current configuration operates with lower conversion and also lower permeation rate of hydrogen but with longer catalyst life than does the reactor in countercurrent configuration.     

油酸异丁酯的离子液体催化酯化制备与动力学及其低温流动性能

在自行设计的反应装置中,以吡啶硫酸氢盐离子液体为催化剂、油酸与异丁醇为反应原料催化酯化制备油酸异丁酯. 得到最佳反应条件为,温度100℃,时间3 h,催化剂用量2%(w),醇/酸最佳体积比2:1. 对此酯化催化反应进行了动力学分析,表观反应级数为二级,反应活化能Ea=32.0 kJ/mol,频率因子A=66.6,反应动力学模型为-dCA/dt=66.6e-32000/(RT)CACB;所制油酸异丁酯的凝点为-25.5℃,冷滤点为-20.5℃,运动粘度为6.32 mm2/s,其低温性能好,流动性能较差,可很好地改进生物柴油的低温性能和油酸异丁酯的流动性能.     

十二烷基磺酸铁催化丙酸异丁酯的绿色合成研究

本文研究了丙酸与异丁醇在十二烷基磺酸铁催化剂作用下的酯化反应,考察了反应时间、催化剂用量、醇酸摩尔比等因素对丙酸异丁酯收率的影响。实验结果表明反应的最佳反应条件为:丙酸用量为 0.1 mol,醇酸摩尔比为1.2,十二烷基磺酸铁用量为2g(约2.5 mmol),反应时间为30 min,酯收率达93.5%,催化剂重复使用5次仍保持较高活性。无污染产生,具有绿色合成的特点。产品经折光率、红外光谱进行了表征。     

硫酸氢钠催化合成乙酸异丁酯

以冰醋酸和异丁醇为原料,在一水合硫酸氢钠的催化作用下合成乙酸异丁酯,探讨了酸醇物质的量比,反应时间及催化剂用量对酯化率的影响。实验结果表明:一水合硫酸氢钠具有较好的催化活性,酸醇物质的量比为1:2.5,反应时间为150min,催化剂用量为1.2g,酯化率达92.33%。     

CeO_2-Ga_2O_3/硅胶的制备及其催化酯化性能研究

制备了铈改性酯化催化剂CeO2-Ga2O3/硅胶,通过催化丙酸与异丁醇的酯化反应考察了其催化酯化性能,并采用IR分析对催化剂进行了表征。催化剂的适宜制备条件为CeO2∶Ga2O3∶硅胶=2.7∶20∶77.3(质量比),500℃焙烧2h。该催化剂对丙酸异丁酯的合成有良好的催化活性,0.20mol丙酸,催化剂用量1.0g,醇酸物质的量比1.4,反应时间90min,酯化率可达98.4%。     

Production and Isolation of n‐Butyl Acrylate Using Pervaporation‐Aided Esterification Reaction: Kinetics and Optimization

Synthesis of n‐butyl acrylate by esterification of acrylic acid with n‐butyl alcohol was carried out in a batch membrane reactor. Optimization and design of the experiment was accomplished by response surface methodology with Box‐Behnken experimental design. The effects of different parameters like reaction temperature, catalyst concentration, molar ratio of alcohol to acid, and ratio of membrane surface to initial volume on water flux and conversion of acrylic acid were evaluated. A kinetic model for the esterification‐coupled pervaporation process was developed. Kinetic parameters were estimated by a nonlinear optimization technique in the MATLAB optimization toolbox. The experimental and simulation results were applied for developing a concept to effectively conduct a pilot‐scale esterification‐pervaporation experiment.     

Membrane reactors in chemical production processes and the application to the pervaporation-assisted esterification

When appropriate membrane was used for the assistance of chemical and biochemical equilibrium reactions, it is possible to enhance the yield and the purity of the reaction product by selectively adding educts or selectively removing products and to a lower the energy input and the reaction time compared to conventional process. In this paper a review on membrane reactors with special emphasis on membrane-assistance of esterification reactions and a continuous tube membrane reactor for the pervaporation-assistance of the esterification are presented. The heterogeneously catalyzed esterification of ethanol and acetic acid to ethyl acetate and water was investigated as a typical chemical equilibrium reaction. The selective and simultaneous water separation from the reaction mixture of the esterification with polyvinyl alcohol pervaporation membranes is considered to be an interesting process alternative to the conventional distillation process. Compared to the distillation process, for the pervaporation-assisted process a decrease of the energy input of over 75% and of the investment and operating coasts of over 50% each was calculated.     

Lipase-Catalysed Esterification Reactions—Experimental and Modelling Studies

A comparative study of supported lipozyme-catalysed esterification of oleic acid with lauryl alcohol, isosorbide and sorbitol in a packed tubular reactor is described. The reaction rate was highest with lauryl alcohol, followed by isosorbide and sorbitol. The esterification reaction between oleic acid and lauryl alcohol was carried out in a tubular recycle reactor and a stirred reactor. Different strategies were used to remove the water formed during the reaction. The rate was found to be highest in the tubular reactor. The reactions were modelled by three bisubstrate models, namely ternary complex random order, Ping-Pong, and Ping-Pong with competitive product inhibition. The third model was found to predict the observed behaviour. © 1997 SCI.     

硫酸氢钠催化合成丁酸异丁酯

硫酸氢钠能够代替硫酸作为酯化作用催化剂。在一水硫酸氢钠存在下，由正丁酸和异丁醇合成了丁酸异丁酯。在正丁酸，异丁醇和硫酸氢钠的物质的量比为4：3：0．07，回流分水60min，酯收率达99．3％，同时研究了催化剂的重复使用性能。     

Enhancement of Methanol Production in a Membrane Dual‐Type Reactor

In this study, a dynamic model for a membrane dual‐type methanol reactor was developed in the presence of long term catalyst deactivation. The proposed model is used to compare the performance of a membrane dual‐type methanol reactor with a conventional dual‐type methanol reactor. A conventional dual‐type methanol reactor is a shell and tube heat exchanger reactor in which the first reactor is cooled with cooling water and the second one is cooled with synthesis gas. In a membrane dual‐type reactor, the wall of the tubes in the gas‐cooled conventional reactor is covered with a palladium‐silver membrane, which is only permeable to hydrogen. Hydrogen can penetrate from the feed synthesis gas side into the reaction side due to the hydrogen partial pressure driving force. Hydrogen permeation through the membrane shifts the reaction towards the product side according to the thermodynamic equilibrium. The proposed dynamic model was validated against measured daily process data of a methanol plant recorded for a period of four years and a good agreement was achieved. The simulation results show that there is a favorable profile of temperature and activity of the membrane dual‐type reactor relative to single and conventional dual‐type reactor systems. Therefore, the performance of methanol reactor systems improves when a membrane is used in a conventional dual‐type methanol reactor.     

稀土化合物对乳酸正丁酯的催化合成

以稀土化合物为催化剂，实现了乳酸与正丁醇反应合成乳酸正丁酯。同时研究了催化剂用量、带水剂用量、酸醇比及反应时间等因素对反应的影响。适宜条件下，酯产率可达８５％以上。