A kinetic study of the reaction between terephthalic acid and ethylene oxide at atmospheric pressure

The kinetics of the reaction of terephthalic acid with ethylene oxide, in n-butanol solvent, catalysed by triethyl amine, were investigated in a semi-batch reactor under atmospheric conditions. It was found that the reaction occurred in the liquid phase and that mass transfer effects were absent. The reaction was found to be pseudo-zero order in terephthalic acid and first order in ethylene oxide and in catalyst concentration. The effects of reaction temperature, catalyst concentration, particle size of terephthalic acid, ethylene oxide flow rate, stirrer speed and terephthalic acid to ethylene oxide ratio were studied. Particle size of terephthalic acid, stirrer speed and flow rate of ethylene oxide did not affect the reaction rate. The Arrhenius activation energy of the reaction was found to be between 19.2 and 23.5 kcal/mol.     

A kinetic study of the reaction between terephthalic acid and ethylene oxide in a nonsolvent system

Kinetics of the reaction between terephathalic acid and ethylene oxide, catalysed by triethylamine, was studied in a high-pressure reactor without using solvent. This reaction was carried out at a temperature range of 80–100°C and at a pressure range of 10–15 Kg/cm² beyond the corresponding vapor pressure of ethylene oxide. Effects of temperature, catalyst concentration, mole ratio of ethylene oxide to terephthalic acid, particle size of terephthalic acid, pK value of the tertiary amine and stirrer speed were experimentally investigated on the yield of bis(2-hydroxyethyl) terephthalate and reaction rates. It was found that the bulk reaction of terephthalic acid with ethylene oxide occurred in the liquid phase. Based on experimental results a reaction mechanism to synthesize bis(2-hydroxyethyl) terephthalate from terephthalic acid and ethylene oxide in a nonsolvent system was proposed, and rate constants were obtained with a model based on this proposed reaction mechanism. The activation energy of the reaction was found to be between 3.67–8.28 kcal/mole in the temperature range of 80–95°C.     

Kinetics of the reaction between terephthalic acid and ethylene oxide under high pressure

Kinetics of the reaction between terephthalic acid and ethylene oxide in n-butanol solvent, catalyzed by triethyl amine, was investigated under high pressure. Effect of temperature, catalyst concentration, ethylene oxide to terephthalic acid ratio and stirrer speed was studied on the rate of formation of bis(2-hydroxy-ethyl)terephthalate. It was found that the reaction of terephthalic acid with ethylene oxide occurred in the liquid phase. The experimental data were correlated with a model based on S_N2 reaction mechanism and the activation energy of the reaction was found to be between 19.3–21.6 kcal/mole in the temperature range of 60–100°C.     

Oxidation of cyclohexanone to adipic acid with a cobalt acetate/oxygen/acetic acid system

The liquid phase oxidation of cyclohexanone to adipic acid at 378 K using oxygen as the oxidising agent and cobalt acetate as the catalyst in an acetic acid medium was investigated both at atmospheric pressure and at a pressure of 0.5MN m⁻². The effects of catalyst concentration, solvent concentration and partial pressure of oxygen, were studied at a constant stirrer speed of 535 rev min⁻¹. Increasing the solvent concentration and decreasing the catalyst concentration (up to 0.113×10⁻³ kmol m⁻³) had positive effects on the overall first order reaction rate constant. It was also found to vary linearly with gas flow rate.     

Poly(ethylene terephthalate) Recycling and Recovery of Pure Terephthalic Acid. Kinetics of a Phase Transfer Catalyzed Alkaline Hydrolysis

Poly(ethylene terephthalate) (PET) taken from post‐consumer soft‐drink bottles was subjected to alkaline hydrolysis with aqueous sodium hydroxide after cutting it into small pieces (flakes). A phase transfer catalyst (trioctylmethylammonium bromide) was used in order the reaction to take place in atmospheric pressure and mild experimental conditions. Several different reaction kinetics parameters were studied, including temperature (70–95°C), NaOH concentration (5–15 wt.‐%), PET average particle size, catalyst to PET ratio and PET concentration. The disodium terephthalate received was treated with sulfuric acid and terephthalic acid (TPA) of high purity was separated. The ¹H NMR spectrum of the TPA revealed an about 2% admixture of isophthalic acid together with the pure 98% terephthalic acid. The purity of the TPA obtained was tested by determining its acidity and by polymerizing it with ethylene glycol using tetrabutyl titanate as catalyst. A simple theoretical model was developed to describe the hydrolysis rate. The apparent rate constant was inversely proportional to particle size and proportional to NaOH concentration and to the square root of the catalyst amount. The activation energy calculated was 83 kJ/mol. The method is very useful in recycling of PET bottles and other containers because nowadays, terephthalic acid is replacing dimethyl terephthalate (the traditional monomer) as the main monomer in the industrial production of PET.     

Kinetics of esterification of benzyl alcohol with acetic acid catalysed by cation-exchange resin (Amberlyst-15)

Esterification of benzyl alcohol with acetic acid catalysed by Amberlyst-15 (cation-exchange resin) was carried out in a batch reactor in the liquid phase in the temperature range 328–359 K and at 1 atm. The reaction rate increased with increase in catalyst concentration and reaction temperature. Resin particle size and stirrer speed had virtually no effect on the rate under the experimental conditions. The rate data were correlated with a kinetic model based on homogeneous reaction. The apparent activation energy was found to be 73.3 kJ mol^?1 for the formation of benzyl acetate.     

Kinetics of acetic acid esterification over ion exchange catalysts

Computer simulation showed that catalytic distillation is an attractive process for the removal of dilute acetic acid from wastewater. Selection of catalysts and kinetic data have been obtained for the design of the catalytic distillation column. Kinetic measurements were conducted in a batch reactor. Methanol was added to the dilute acetic acid solutions and reacted with the acid in water to form methyl acetate and water. The reaction can be catalyzed by solid acid catalysts. It was found that Amberlyst 15 was an effective catalyst for this reaction. The effects of stirrer speed, reaction temperature, reactant concentration and catalyst loading on reaction rate were investigated. A complete kinetic equation for describing the reaction catalyzed by Amberlyst 15 was developed. This equation can be used in the simulation and design of the catalytic distillation column for removing acetic acid from wastewater.     

内循环式无梯度反应器的研究

设计了一种内循环式无梯度反应器,可用以进行气固相催化反应动力学的研究。反应器的结构简单。采用电磁搅拌器以克服旋转轴径向密封的困难。催化剂可静置于多孔板上,或放在转篮中与轴一起运动。催化剂的粒度从零点几毫米至工业粒度均可适用。经停留时间分布测定证明反应器内气体的流动状况属于理想混合。径向及轴向的温度差甚小。这种反应器可以在800℃以下的温度操作。 研究了不同的气体体积流量下停留时间分布和搅拌速率间的关系。为了达到完全混合状态,较高的气体流量要求较高的搅拌速率。此外,在不同的搅拌速率下,还测定了反应器出口反应物的浓度,当搅拌速率增加至某一定数值后,组成不再改变。     

Esterification of decanoic acid with methanol using Amberlyst 15: Reaction kinetics

Methyl decanoate is used as a surrogate fuel. The surrogate fuels are structurally similar to actual biodiesel. We synthesized methyl decanoate in a small batch reactor by esterification reaction using decanoic acid and methanol on solid acid catalyst Amberlyst 15 used in dry state. The outcome of different reaction parameters including catalyst loading, temperature, molar ratio, stirrer speed, water concentration effect, and adsorption on catalyst pellets were studied for optimization of rate of conversion. The effect of external and internal diffusion limitations on catalyst granules was calculated theoretically from the reaction kinetics data. An analysis of the reaction kinetics revealed that the esterification reaction was rate controlled by adsorption of methanol on the solid acid catalyst and the reaction can be modeled as Eley–Rideal model. Activation energy of the esterification reaction was 39.4?KJ/mol. Reaction enthalpy and entropy were found to be 29.81?kJ/mol and 87.38?J/mol. K, respectively.     

催化精馏合成乙二醇乙醚的研究

催化精馏是将固体催化剂布于精馏塔内,它既加速了化学反应,又可作为分离过程的传质表面。本文研究了在内径为35mm的不锈钢塔中,用NKC—01催化剂从乙醇和环氧乙烷合成乙二醇乙醚(单醚)的过程,详细考察了进料比,操作压力,处理量等因素对过程的影响,找到的适宜条件为:进料比(乙醇/环氧乙烷)=6～8(摩尔);处理量为104.0Nm~3环氧乙烷/h(m~3催化剂);操作压力=2.35×10~5Pa。在此条件下乙二醇乙醚对环氧乙烷的收率为90％(mol);环氧乙烷的单程收率为93％;乙二醇乙醚的选择性为97％。为考察塔内的流体力学条件对催化反应的影响,在搅拌容器中测定了过程的反应动力学。为保证此搅拌容器中的液体流速接近塔内操作条件下的流速,以确定适宜的搅拌器转速,我们用DANTEC MODEL 2020激光测速仪测定了不同搅拌器转速下容器中液体的流速。通过研究可以看出:在塔内的操作条件下,与化学反应相比,扩散阻力可以被忽略。     

对苯二甲酸和1,4丁二醇的单酯化催化动力学

文章主要是研究了对苯二甲酸和1,4丁二醇的单酯化反应动力学。该酯化的反应级数是通过初始速率法测得的。该反应应用的催化剂是丁基锡酸和钛酸四丁酯。实验结果显示对苯二甲酸的反应级数是根据催化剂的不同而在2到0.7之间变化的。反应活化能和速率常数也分别被测得。     

Kinetic study of catalytic esterification of acrylic acid with butanol catalyzed by different ion exchange resins

The esterification of acrylic acid and n-butanol catalyzed by three different ion exchange resins, Amberlyst 15, Amberlyst 131 and Dowex 50Wx-400 was studied. Amberlyst 131 was found to be more efficient catalyst giving the maximum conversion of acrylic acid. The effects of temperature, molar ratio of alcohol to acid, stirrer speed and catalyst loading on the reaction rate were investigated. The chemical equilibrium constants were obtained experimentally and theoretically from thermodynamic properties. The experimental data were tested with four different reaction mechanisms according to adsorption status of reactants. The activity coefficients were calculated using UNIQUAC method to account for the non-ideal thermodynamic behavior. The activation energy was found to be 57.4 kJ/mol according to the LHHW model which correlates the experimental data with minimum error.     

Liquid-phase esterification of acetic acid with isobutanol catalyzed by ion-exchange resins

Esterification of carboxylic acids with alcohols represents well-known liquid-phase reactions of considerable industrial interest due to the importance of organic ester products. These ester products include environmentally friendly solvents, flavors, pharmaceuticals, plasticizers, and cosmetics.In this study, the esterification kinetics of acetic acid with isobutanol in 1,4-dioxan as a solvent without adding a catalyst and catalyzed by ion-exchange resins are carried out using a batch reactor. The effect of catalyst type, stirrer speed, the effects of reaction temperature and catalyst loading on the initial reaction rate, the effect of speed of agitation and the conversion of acetic acid versus time were investigated. The kinetics of heterogeneous catalyzed esterification of acetic acid with isobutanol was correlated by a kinetic model based on pseudo-homogeneous catalysis. The strong acidic cation exchange resins were used as solid catalysts, Dowex 50 Wx2, Amberlite IR-120, respectively. As a result, it was found that the weight-based activity of the heterogeneous catalysts increases in the following order: Dowex 50 Wx2 > Amberlite IR-120 and these catalysts were effectively for the synthesis of isobutyl acetate under these experimental conditions.     

超重力液相沉淀法制备纳米铁酸钴

针对磁力搅拌器制备纳米材料时存在粒径分布宽、分散不均匀的问题,采用撞击流-旋转填料床结合化学共沉淀法,以Fe（NO₃）₃·9H₂O、Co（NO₃）₂·6H₂O、NaOH为原料制备CoFe₂O₄纳米颗粒。研究了转速、液体流量、NaOH浓度以及晶化时间对CoFe₂O₄纳米颗粒粒径的影响;并与磁力搅拌器制备的CoFe₂O₄纳米颗粒在磁性能方面进行了对比。采用X射线衍射仪（XRD）、傅里叶红外光谱仪（FTIR）、透射电镜（TEM）、纳米粒度仪及振动样品磁强计（VSM）对产物的粒径形貌及磁性能进行表征。结果表明：CoFe₂O₄纳米颗粒的粒径随转速、液体流量和NaOH浓度的增加而减小,但随晶化时间的增加而增大。最佳工艺条件为：转速900r/min,液体流量60L/h,NaOH浓度3mol/L,晶化时间6h。此条件下制备的CoFe₂O₄纳米颗粒的粒径约为20nm,饱和磁化强度为75.43emu/g,较磁力搅拌器提高40%。     

Reactions of trithiocyanuric acid with oxiranes. II. Kinetics and mechanism of reactions

The study of the kinetics of the addition of trithiocyanuric acid to oxiranes (i.e., ethylene oxide and propylene oxide) in DMSO solution in the presence of triethylamine as a catalyst is described. The effects of the acid group concentration, the concentration of oxirane, and the catalyst on the course of the reaction was studied. The rate equation describing the addition was derived. The reaction order with respect to the oxirane, catalyst, and reactive groups of the acid were 0.5, 0.5, and 1.5, respectively. The mechanism of addition was proposed. The influence of temperature on the course of the reaction was also studied. The activation parameters (ΔH^#, ΔS^#, ΔG^#) were calculated. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 2081–2088, 2000     

Vapour phase oxidation of ethylene glycol to glyoxal on supported cupric oxide

The vapour phase oxidation of ethylene glycol to glyoxal by air was studied in a stainless steel tube reactor using cupric oxide as a catalyst on carriers such as active alumina, pumice stone, silicon carbide, ceramics and fused alumina. A catalyst containing 3 to 5% cupric oxide on pumice stone was found to be satisfactory for the process. The effects of temperature, period of reaction and concentration of ethylene glycol and oxygen on the yield and conversion to glyoxal were studied, and the most suitable conditions were determined for the process. Carbon dioxide and formaldehyde were the major by-products in the reaction. Formaldehyde was formed mainly due to the homogeneous reactions of ethylene glycol with oxygen in the void space of the reactor. The formation of glyoxal and carbon dioxide were correlated by suitable empirical rate expressions.     

纤维级PBT的研制

采用精对苯二甲酸酯化法制备纤维级PBT,利用方差分析方法比较了PBT性能对可纺性的影响,并对PBT端羧基含量的影响因素进行了正交试验。结果表明,PBT的热性能和相对分子质量分布对可纺性影响不明显,而其端羧基含量影响显著。控制PBT端羧基含量的最佳工艺为:催化剂浓度120μg／g,酯化温度240℃,终缩聚釜搅拌器转速5 r／min。     

松香低压催化加氢反应的研究

采用 FYX-2 G型高压搅拌釜 ,在温度 1 60°C、压力 1 .0 MPa条件下 ,测定了松香催化加氢转化率与 Pd/ C催化剂含水量的关系 ,可见加氢反应速度随催化剂含水量的减少而增加。考察了搅拌器类型、搅拌转速对高压釜持气量及枞酸转化率的影响 ,认识到松香催化加氢是外扩散控制的反应 ,当搅拌转速达 60 0 r/ min时 ,基本上能消除外扩散的影响。比较了 Raney-镍与 Pd/ C催化剂对松香催化加氢的活性 ,实验表明在低氢压 1 .0 MPa下 ,只有 Pd/ C催化剂才能制备出合格的氢化松香产品     

对苯二甲酸-丁二醇催化单酯化反应动力学(英文)

The chemical kinetics of the monoesterification between terephthalic acid (TPA) and 1,4-butanediol (BDO) catalyzed by a metallo-organic compound was studied using the initial rate method. The experiments were carried out in the temperature range of 463-483 K, and butylhydroxyoxo-stannane (BuSnOOH) and tetrabutyl titanate [Ti(OBu)4] were used as catalyst respectively. The initial rates of the reaction catalyzed by BuSnOOH or Ti(OBu)4 were measured at a series of initial concentrations of BDO (or TPA) with the concentration of TPA (or BDO) kept constant. The reaction orders of reagents were determined by the initial rate method. The results indicate that the reaction order for TPA is related with the species of catalyst and it is 2 and 0.7 for BuSnOOH and Ti(OBu)4 respectively. However, the order for BDO is the same 0.9 for the two catalysts. Furthermore, the effects of temperature and catalyst concentration are investigated, and the activation energies and the reaction rate constants for the two catalysts were deter-mined.     

酯化法合成对苯二甲酸二(β-羟乙基酯)的研究

以对苯二甲酸和乙二醇为原料,采用自制催化剂合成出了对苯二甲酸二(β-羟乙基酯)(BHET).最佳反应条件:1 mol对苯二甲酸使用0.2 g催化剂,醇酸摩尔比为12∶1,反应时间为10h,反应温度为185℃.粗品经结晶、重结晶可得质量分数＞99％的BHET产品.