酯交换合成乙二醇二乙酸酯的动力学研究

为了给乙二醇二乙酸酯的工业生产提供动力学支持,文章在间歇反应釜中对乙酸仲丁酯和乙二醇酯交换合成乙二醇二乙酸酯的反应进行研究。筛选出NKC-9阳离子交换树脂为较优催化剂,并考察搅拌转速、催化剂用量、反应温度以及酯醇摩尔比等因素对反应过程的影响,确定较优的实验条件为搅拌转速400 r/min,催化剂用量为乙二醇质量的35%,反应温度382.15 K,酯醇摩尔比为6∶1。建立拟均相动力学模型,通过对367.15—382.15 K的实验数据进行拟合,得到酯交换合成乙二醇二乙酸酯的反应动力学方程,并通过实验与计算值的比较验证,此反应动力学方程合理,可用于模拟计算。     

酯交换法合成仲丁醇的动力学研究

为了给仲丁醇的工业生产提供动力学支持,文中研究了甲醇与醋酸仲丁酯在间歇反应釜中以NKC-9型阳离子交换树脂为催化剂通过酯交换反应合成仲丁醇的动力学过程。在消除内外扩散的影响下,考察了反应温度、催化剂用量以及醇酯摩尔比等因素对醋酸仲丁酯转化率的影响,得到了适宜的操作条件并建立了拟均相动力学模型。通过对323.15—348.15 K下的实验数据进行拟合,得到酯交换合成仲丁醇的反应动力学方程,并通过了实验与计算值的比较验证,此反应动力学方程合理,可用于模拟计算。     

氯乙酸的碱水解反应动力学实验

氯乙酸中的氯是活性基团,利用其活泼性可进行烃化反应,广泛应用于农药、医药、染料、CMC的合成。 AR—ZH+ClCH_2CO_2H→ARZCH_2CO_2H (Z=C、N、O)     

低聚合度含氢硅油的合成条件及工艺研究

低聚合度含氢硅油是改性硅油的重要中间体,因为其分子中含有活泼氢,可用于合成各种性质的改性硅油。由低聚合度含氢硅油制备的改性硅油具有良好的分散性、独特的挥发性,以及低表面张力,常被用作个人护理产品中的添加剂。目前文献报道较集中于低含氢硅油高聚物,对于低含氢硅油中纯组分的合成及性质尚待探寻。MD₁₀₀D₁₀^HM作为低聚合度含氢硅油中的纯组分具有很好的代表性。本文通过正交试验得出合成MD₁₀₀D₁₀^HM的最佳催化剂为NKC-9阳离子交换树脂,采用单因素实验在中试过程中进一步对MD₁₀₀D₁₀^HM的合成进行优化,得出最佳条件为：反应温度50℃,催化剂用量2%,反应时间2h。     

叔丁醇脱水反应动力学研究

以国产NKC-9型强酸性阳离子交换树脂为催化剂,在常压液相下进行了叔丁醇脱水的反应动力学研究,为由叔丁醇脱水生产异丁烯工艺的开发提供了基本理论依据。在消除内外扩散影响下,讨论了反应温度、反应物初始浓度和催化剂用量等条件对反应速率的影响。结果表明：反应温度升高,将加快反应速率：水的存在对此反应过程产生阻碍效应,随着反应物初始浓度中水含量的增加,反应速率减小。考虑异丁烯在液相中含量很低以及产物水对反应的阻碍效应,建立了该反应的动力学模型,并得到了相应的模型参数。在实验温度范围内,速率模型计算结果与实验结果吻合较好。     

淀粉—聚丙烯腈水解反应的研究

本文应用正交设计法,对影响淀粉-聚丙烯腈(S-PAN)水解反应的四种因素:即反应时间、反应温度、氢氧化钠浓度和接枝共聚物浓度进行了研究,通过数理统计优选出水解反应的最佳工艺条件。     

乙基叔丁基醚(ETBE)的催化反应动力学研究

用国产 S型强酸性阳离子交换树脂为催化剂 ,在常压液相条件下用乙醇 (Et OH)和叔丁醇 (TBA)合成了乙基叔丁基醚 (ETBE)。讨论了温度、催化剂浓度、反应物初始摩尔比等参数对反应速度的影响 ,考察了水对反应的阻害效应以及反应体系的体积变化原因 ,建立了一个反应动力学模型 ,实验结果与模型计算值较为吻合     

醋酸甲酯合成的反应动力学

醋酸甲酯是重要的工业原料,作为高纯度醋酸甲酯合成的基础研究。研究了在常压、温度40~55℃下,用阳离子树脂作为催化剂催化反应合成醋酸甲酯的本征反应动力学。通过改变搅拌速度和离子直径,消除了内外扩散的影响,得到了基于Langmuir-Hinshelwood吸附理论的用活度代替浓度的通用动力学模型。经过实验研究表明,醋酸甲酯合成反应为放热反应,平衡常数K随温度的升高而降低。通过拟合得到醋酸甲酯合成反应的活化能为59.234 kJ·mol-1。     

用离子交换树脂催化水解醋酸甲酯的反应动力学研究

研究了在常压下、温度为３０８～３２８Ｋ的范围内，用阳离子交换树脂作催化剂的醋酸甲酯催化水解宏观反应动力学。建立了实验条件下的动力学模型。研究了反应温度、催化剂浓度、水酯比、催化剂装填方式及进料中含甲醇等因素对催化水解的影响。实验数据采用拟均相二级反应动力学模型进行回归，得出醋酸甲酯催化水解的正逆反应活化能为３５．５和２９．５ｋＪ／ｍｏｌ。与催化剂浓度关联的最终速率表达式为：ｋ＋＝（５．３９２７９×１０－１０Ｃ－２．０７２０５９×１０－８）ｅｘｐ（－４．２７０／Ｔ）ｋ－＝（５．９１０６６×１０－１０Ｃ－１．５１５４３×１０－８）ｅｘｐ（－３．４２８／Ｔ）     

乙酸辛酯的合成及其动力学研究

以阳离子交换树脂NKC-9为催化剂,乙酸和辛醇为原料合成乙酸辛酯,考察乙酸和辛醇摩尔比、催化剂用量和反应时间等因素对辛醇转化率的影响,以及催化剂的重复使用性能。结果显示,乙酸辛酯合成的较佳工艺条件为:n(乙酸)∶n(辛醇)=4∶1,反应时间为3 h,催化剂用量为乙酸和辛醇总质量的6%,反应温度为118~120℃,在此条件下辛醇转化率可达96.80%,且催化剂活化后可重复使用。分别采用正反应常数法和初始反应速率法测定阳离子交换树脂NKC-9催化合成乙酸辛酯的动力学模型参数,获得了可逆二级动力学方程的参数,表观活化能和指前因子分别为:正反应常数法E_a=38.74 k J/mol,k0=7.45×10~2L/(mol·min);初始反应速率法E_a=37.45 k J/mol,k_0=4.79×10~3L/(mol·min)。2种方法测定结果基本一致,印证了该理论数据的可靠性。     

油酸甲酯合成反应动力学研究

油酸甲酯是一种重要的化工原料,因现行生产工艺存在污染环境、腐蚀设备、反应转化率较低等问题,使其生产受到了一定制约,为此,提出了一种无催化"两步法"合成油酸甲酯的工艺路线。文中在"两步法"工艺路线的基础上进一步研究了油酸甲酯合成反应动力学。采用积分法分析了在293,298,303,308,313 K下的实验数据,结果表明二步反应均符合二级反应特征,反应遵循四面体机理,并得到了不同温度下的动力学方程式。根据得到的不同温度下的反应速率常数确定了二步反应的活化能分别为121.6 kJ/mol和115.2 kJ/mol,频率因子为2.76×1019和4.03×1018。在实验293—313 K温度范围内,通过实验对得到的动力学方程进行验证,得到的实验值与动力学方程计算值相符合,说明得到的动力学方程是可靠的,为"两步法"合成油酸甲酯的工业放大提供了理论依据。     

Formation of methyl methacrylate from methyl propionate and methanol

The formation of methyl methacrylate (MMA) was studied in a vapor-phase reaction between methyl propionate (MP) and methanol without using any sources of formaldehyde. Silica-supported CsOH doped with a small amount of silver Ag was found to be the best catalyst. The optimum Ag/Cs/Si atomic ratio was 4–10/20–25/1000. When the reaction was performed in the absence of oxygen in the feed, the main product was methyl isobutyrate (MIB) at the beginning of the reaction; MMA was not obtained. As the time-on-stream increased, the formation of MIB fell, while that of MMA increased, showed a maximum, and then decreased gradually. In the case of the reaction performed in the presence of oxygen, the catalytic activity was stable. As the amount of oxygen increased, the yield of MMA increased, while the selectivity fell. The performances were further improved by the combination of a small amount of Ag–Cs/SiO₂ catalyst and a large amount of Cs/SiO₂ catalyst.     

Reaction kinetics of irradiation- prepolymerized methyl methacrylate-polyurethane interpenetrating polymer networks by FTIR

The reaction kinetics of irradiation-prepolymerized MMA-PU (polyether) IPNs have been studied by FTIR. The results indicate that the polymerization of each component in the IPN follows its normal distinct reaction mechanism with no mutual interference. Increasing the concentration of TMPTMA (crosslinking agent of PMMA) increased the formation rate of PMMA, while the formation rate of PU networks remained almost the same. Increasing the concentration of TMP (crosslinking agent of PU) increased the formation rate of PU, while the formation rate of PMMA networks decreased. The formation rate of PU was obviously faster than that of PMMA. A theory for the cage effect of the PU network has been proposed.     

高自由酸油脂甲酯化反应动力学与相分离模拟

为了降低生物柴油的生产成本、提高过程效率,研究了高自由脂肪酸油脂一步法制取脂肪酸甲酯的催化剂体系.提出水解-酯化耦合反应机理,建立拟均相催化反应动力学模型,并借助多物理场模拟软件COMSOL Multiphy-sics和流程模拟软件Aspen Plus 11对甘油水混合物与脂肪酸甲酯的分离过程和相平衡进行模拟研究.结果...     

Photodegradation kinetics of methyl salicylate in poly(methyl methacrylate)

It has been found that methyl salicylate (MS) undergoes a photoinduced decarboxylation to form phenol with a quantum yield of ca. 8 × 10^?5. The reaction is first order and the rate constant is proportional to the irradiance used. An activation energy of 1.2 kcal/mol was determined. Computer simulations were used to predict whether sufficient UV screening would be provided by MS-containing PMMA lenses over the projected lifetime of solar photovoltaic devices. An effective screening lifetime of less than 2 years is predicted.     

Reaction kinetics of carboxymethylation of cornstarch

Reaction kinetics of carboxymethylation of cornstarch in the reaction media of ethanol was studied in this article by determining the changes of NaOH concentration and degree of substitute of reacting matter in the reaction process at different temperature. The equation of reaction rate has been set up and proved to be corresponding with the second‐order reaction. The main and side reaction rate constants at different temperature and the main and the side reaction activation energy have been obtained, respectively. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Ru/AlOOH催化丙酸甲酯加氢反应研究

采用浸渍、水热还原的方法制备了Ru/A lOOH催化剂,进行了XRD表征。以水作溶剂,考察了该催化剂对丙酸甲酯的催化加氢性能。结果表明,催化剂中金属以Ru0存在,并且很好的分散在载体A lOOH上;反应时间、温度、氢气压力和溶剂体积对丙酸甲酯加氢转化率和目标产物丙醇选择性都有很大的影响。在180℃、氢压5 MPa条件下,反应10 h,丙酸甲酯的转化率达到85.9%,丙醇的选择性为94.0%。     

2-甲氧羰基-3-(4-羟苯基)丙酸甲酯的合成

4-苄氧基苯甲醛(Ⅱ)与丙二酸二甲酯脱水缩合,产生2-甲氧羰基-3-(4-羟苯基)丙烯酸甲酯(Ⅲ),收率为88%,化合物(Ⅲ)经过催化氢化,以95%的收率得到中间体2-甲氧羰基-3-(4-羟苯基)丙酸甲酯(Ⅰ),(Ⅰ)的合成总收率达到73.6%。产品的结构经过IR、ESI-MS1、H NMR确证。     

Reaction kinetics of isopropyl palmitate synthesis

In this study, the kinetics of isopropyl palmitate synthesis including the reaction mechanism was studied based on the two-step noncatalytic method. The liquid-phase diffusion effect on the reaction process was eliminated by adjusting the stirring rate. The results showed that the two-step reaction followed a tetrahedral mechanism and conformed to second-order reaction kinetics. Nucleophilic attack on the carbonyl carbon afforded an intermedi-ate, containing a tetrahedral carbon center. The intermediate ultimately decomposed by elimination of the leav-ing group, affording isopropyl palmitate. The experimental data were analyzed at different temperatures by the integral method. The kinetic equations of the each step were deduced, and the activation energy and frequency factor were obtained. Experiments were performed to verify the feasibility of kinetic equations, and the result showed that the kinetic equations were reliable. This study could be very significant to both industrial application and determining the continuous production of isopropyl palmitate.