Kinetics of epoxidation of jatropha oil with peroxyacetic and peroxyformic acid catalysed by acidic ion exchange resin

The kinetics of epoxidation of jatropha oil by peroxyacetic/peroxyformic acid, formed in situ by the reaction of aqueous hydrogen peroxide and acetic/formic acid, in the presence of an acidic ion exchange resin as catalyst in or without toluene, was studied. The presence of an inert solvent in the reaction mixture appeared to stabilise the epoxidation product and minimise the side reaction such as the opening of the oxirane ring. The effect of several reaction parameters such as stirring speed, hydrogen peroxide-to-ethylenic unsaturation molar ratio, acetic/formic acid-to-ethylenic unsaturation molar ratio, temperature, and catalyst loading on the epoxidation rate as well as on the oxirane ring stability and iodine value of the epoxidised jatropha oil were examined. The multiphase process consists of a consecutive reaction, acidic ion exchange resin catalysed peroxyacid formation followed by epoxidation. The catalytic reaction of peroxyacetic/peroxyformic acid formation was found to be characterised by adsorption of only acetic (or formic) acid and peroxyacetic/peroxyformic acid on the active catalyst sites, and the irreversible surface reaction was the overall rate determining step. The proposed kinetic model takes into consideration two side reactions, namely, epoxy ring opening involving the formation of hydroxy acetate and hydroxyl groups and the reaction of the peroxyacid and epoxy group. The kinetic and adsorption constants of the rate equations were estimated by the best fit using nonlinear regression method. Good agreement between experimental and predicted data validated the proposed kinetic model. From the estimated kinetic constants, the apparent activation energy for epoxidation reaction was found to be 53.6 kJ/mol. This value compares well with those reported by other investigators for the same reaction over similar catalysts.     

Kinetic parameters of a two-phase model forin situ epoxidation of soybean oil

The process ofin situ epoxidation consists of a two-phase system that involves reactions in both phases, mass transfer between phases, and thermodynamic driving forces for the mass transfer. In this paper, we present a model that treats the process as a two-phase system and uses local phase concentrations to calculate reaction and mass transfer rates. The process ofin situ epoxidation has been broken down into a set of systematic steps, and rate constants for each step have been determined. A conventional stirred tank reactor, equipped with cooling coils, eliminated the heat and mass transfer limitations so that the true kinetics ofin situ epoxidation were observed. It is shown that significantly larger rates (larger by factors of 2–10) are obtained when heat and mass transfer limitations are removed. The two-phase model adequately predicts the epoxidation kinetics over a wide range of temperatures (50–90°C). In addition, the model also correctly predicts the effect of adding an inert solvent.     

Epoxidation of karanja (Pongamia glabra) oil catalysed by acidic ion exchange resin

Karanja oil with an iodine value of 89 g/100 g was epoxidised in situ with aqueous hydrogen peroxide and acetic acid in the presence of Amberlite IR‐120 acidic ion exchange resin as catalyst. The effect of the operating variables on the oxirane oxygen content, as well as on the oxirane ring stability and the iodine value of the epoxidised karanja oil, were determined. The variables studied were stirring speed, hydrogen peroxide‐to‐ethylenic unsaturation molar ratio, acetic acid‐to‐ethylenic unsaturation molar ratio, temperature, and catalyst loading. The effects of these parameters on the conversion to the epoxidised oil were studied and the optimum conditions for the maximum oxirane content were established. The proposed kinetic model takes into consideration the two side reactions, namely, epoxy ring opening involving the formation of hydroxy acetate and hydroxyl groups, and the reaction between the peroxyacid and the epoxy group. The kinetic and adsorption constants of the rate equations were estimated by the best fit using Marquardt's algorithm. Good agreement between experimental and predicted data validates the proposed kinetic model. From the estimated kinetic constants, the apparent activation energy for the epoxidation reaction was found to be 11 kcal/mol.     

Kinetics of methyl tertiary butyl ether synthesis catalyzed by ion exchange resin

This paper presents the results of an experimental investigation of the kinetics of liquid phase reaction between methanol and isobutene, catalyzed by an acidic ion-exchange resin, to form methyl tertiary butyl ether (MTBE). A one litre Parr batch reactor was used. Experiments were carried out at 70, 80, 90 and 100°C and at pressures sufficient to maintain liquid phase at those temperatures. Initial methanol/isobutene mole ratios of 1.0 and 2.0 were used. The catalyst amount was also varied. These kinetic data were used to model the reaction kinetics, by non-linear least squares regression technique. The reaction was found to follow Rideal-Eley kinetics. The values of the rate constants are reported.     

Liquid phase synthesis of methyl tert-butyl ether catalyzed by ion exchange resin

Synthesis of methyl tertiary butyl ether (MTBE) from methanol and isobutene was studied using macroporous cation exchange resin, Amberlyst 15 in the hydrogen form, as a catalyst in the temperature range of 313-328 K. The reaction was carried out in a batch reactor at a pressure of one atmosphere in the liquid phase. A high degree of agitation was maintained in order to eliminate film diffusion resistance. The effect of catalyst loading, catalyst particle size and reaction temperature on reaction rate were studied. The reaction rate increased with increase in catalyst concentration and reaction temperature. Resin particle size had virtually no effect on the rate under the experimental conditions. The reaction rate data were analysed using homogeneous kinetics and heterogeneous models based upon Langmuir-Hinshelwood rate expressions. The apparent activation energies using homogeneous and heterogeneous models were determined and found as 79.0 kJ/mol and 76.7 kJ/mol respectively.     

改性离子交换树脂催化合成醋酸仲丁酯

采用几种金属离子和阳离子交换树脂反应,制备了不同的改性树脂催化剂,并考察了其催化活性。研究结果表明:分别以SnCl4、AlCl3和ZnCl2为改性剂制得的催化剂活性均较未改性树脂催化剂活性有较大的提高,其中以SnCl4为改性剂的效果最好,醋酸转化率由未改性的35%提高到70%左右。催化剂稳定性实验表明,随着反应次数的增加,醋酸转化率逐渐提高并趋于稳定,说明改性催化剂稳定性良好。     

Kinetic of copper ion exchange onto iminodiacetic resin

The internal porosity and swelling/shrinking of a chelating iminodiacetic type ion exchange resin have been experimentally studied during the uptake of copper onto it. The swelling of the particle could be analyzed with a modified model on th basis of the unreacted core model (UCM), including the influence of chemical equilibrium. The ion exchange kinetic results in batch experiments are used with the UCM to calculate the effect of pH on the internal diffusion coefficients. Results from shallow bed experiments with mixed internal and external diffusion controls have shown the applicability of the above model to analyze ion exchange with low external velocities.     

离子交换树脂去除水中硝酸盐的研究

对比研究了国内生产的5种阴离子交换树脂(D201、D301、D407、330、717)对水中NO3-的吸附解吸情况。动态吸附饱和曲线表明,717和D407对NO3-的吸附较好,饱和吸附量分别为82.8mg/mL和54.8mg/mL,其他3种树脂效果很差;717和D407对NO3-的吸附速率也相对较快。5种树脂吸附等温线与经验公式拟合的线性相关性显著,其中330树脂符合BET经验公式,另外4种树脂符合Langmuir经验公式;再生试验表明5种树脂再生率均能达到85%以上。综合研究结果认为,强碱性苯乙烯系阴离子交换树脂717和螯合树脂D407对NO3-具有较好的吸附解吸性能,可作为去除硝酸盐的选用树脂。     

Ion chromatographic determination of phosphorus and tungsten in epoxidized soybean oil

Soybean oil has been epoxidized with hydrogen peroxide in the presence of catalytic amounts of trioctylmethyl-ammonium tetra(diperoxotungsto)phosphate. A fast ion-exchange chromatographic method with suppressed conductivity detection has been developed for determining residual contents of tungsten and phosphorus in the oil. Tungsten and phosphorus could be determined at concentrations of 66 and 11 ppm, respectively. At tungsten and phosphorus concentrations of 1000 and 50 ppm, measured repeatabilities were 1.3 and 1.5%, respectively.     

离子交换树脂在纯水制备方面的应用

本文详解了离子交换树脂在纯水制备方面的应用。阐述了用离子交换树脂生产超纯水、高纯水的工艺流程及其特点,综述了离子交换树脂在纯水制备方面的应用现状。     

离子交换树脂塔运行方式分析

对螯合树脂塔运行方式进行阐述,分析双塔运行的可行性及三塔运行中操作周期延长的问题。     

Kinetics of catalytic transfer hydrogenation of soybean oil

The catalytic transfer hydrogenation of soybean oil was studied by using various concentrations of sodium formate solutions, an emulsifier and paladium on a carbon catalyst. Sodium formate concentration and addition of the emuldifier significantly affect the reaction rate because of their influence on the liquid/liquid interface. Under conditions in which diffusion effects are eliminated, all reactions carried out in diluted sodium formate solution obey first-order kinetics with respect to fatty acids. This allows control over the hydrogenation process of soybean oil, needed to obtain partially hydrogenated oil containing about 1% linolenic acid and a relatively high level of linoleic acid with no increase in the stearic acid concentration.     

Kinetics of metal ion exchange in iminodiacetic resins at low concentrations

The kinetics of metal exchange processes with iminodiacetic chelating resin, which occurs with metal concentration change, has been studied. Mechanisms of rate control were analyzed, and diffusivities determined from experiments in batch solutions with decreasing metal concentrations, following the unreacted core model. Metal exchange in binary and ternary systems are analyzed and diffusivity variations of these systems discussed in terms of reaction fronts. The influence of temperature was also studied and energies of activation determined.     

通过Michael反应制备脂肪磺酸基强酸型阳离子交换树脂

以乙二胺化交联聚苯乙烯树脂(PS-Acyl-EDA)和2-丙烯酰胺基-2-甲基丙烷磺酸(AMPS)为原料,通过Michael反应合成脂肪磺酸基强酸型阳离子交换树脂。该磺酸基强酸型阳离子交换树脂与传统的磺酸树脂相比,具有较长的手臂链,易于和其他物质反应或进行离子交换,且避免了芳香族磺酸树脂的磺化逆反应。讨论了反应时间、反应温度、催化剂用量、试剂用量及投料比等因素对反应结果的影响。通过对反应条件的优化,可获得担载量为0~1.15mmol•g^-1的磺酸基强酸型阳离子交换树脂,并对产物进行了表征。该方法可用于色谱预装柱填料的制备。     

硫酸高铈改性离子交换树脂催化合成尼泊金丁酯

首次采用硫酸高铈与阳离子交换树脂反应制备的改性离子交换树脂为催化剂合成尼泊金丁酯。考察了催化剂用量、醇酸物质的量比、反应时间及带水剂等因素对收率的影响。结果表明,该催化剂具有催化活性高、后处理方便,废液排放量少等优势。最佳反应条件为:醇酸物质的量比3,催化剂0.5 g,反应时间5 h,收率达93.1%。     

Hydrolysis of palm oil catalyzed by macroporous cation-exchanged resin

Hydrolysis of palm oil was studied using four types of commercial H⁺-exchanged resin with acidity in the region of 5×10⁻³ eq g⁻¹ but with different pore volumes, specific surface areas, and pore diameters. The reaction was carried out in a stirred batch reactor in the liquid phase with continuous steam injection for up to 14 h. The rate of hydrolysis did not depend on total pore volume and specific surface area but did depend on pore diameter. On exchanging H⁺ with La³⁺, Co²⁺, and Na⁺, the rate of reaction decreased markedly and was dependent on the degree of exchange, demonstrating that hydrolysis was catalyzed by H⁺ sites. The activation energy for the hydrolysis of the triglycerides was estimated to be 240 kJ mol⁻¹. A procedure to estimate the rates of the different stages of hydrolysis and hence the individual rate constants of the forward and reverse reactions is described. The procedure yielded reasonable parameters for the reaction at 155°C up to 6 h of reaction time, when about 75 mol% of triglycerides was hydrolyzed.     

Lead removal from aqueous solutions by 732 cation‐exchange resin

Kinetics and thermodynamics of the removal of Pb²⁺ from an aqueous solution by 732 cation‐exchange resin in hydrogen type (732‐CR) were studied in the temperature range of 298–328 K and Pb²⁺ concentration range of 5–50 mol/m³. The effects of ion exchange temperature and initial lead ion concentration on the time evolution of the experimental concentration for the metal ion were investigated. Ion exchange kinetics of Pb²⁺ onto 732‐CR follow the Nernst‐Planck equation and unreacted‐core model (UCM). The diffusion coefficients of counter ions and the efficient diffusion coefficient of lead ions within the resin were calculated. The results show that the ion exchange process is favoured under the particle diffusion control mechanism. The ion exchange isotherm data agreed closely with the Langmuir isotherm. The maximum monolayer exchange capacity for Pb²⁺ was found to be 484.0 mg/g at 308 K. Thermodynamic studies show that Pb²⁺ onto 732‐CR is spontaneous and exothermic in nature. The ion exchange processes were verified by Energy Disperse Spectroscopy (EDS).     

Removal of nickel from effluents by chelating ion exchange

BACKGROUND: Nickel is a highly toxic metal which is discharged into receiving waters by several industries, in particular, electroplating, PCB and electronics manufacturers. In the present study, a new ion exchanger has been assessed for its ability to remove nickel from solution. RESULTS: By comparing the SSE of different models in the nickel metal ion system, it seems that Redlich‐Peterson isotherm was the best fit model for the three metal ions. But the Langmuir was of a very similar magnitude. The equilibrium sorption capacity has been determined as 2.18 mmol/g and the batch contact time studies have been analyzed and compared using three kinetic models. The rate data were best correlated using the Elovich kinetic model. CONCLUSION: The batch sorption system is a well developed system for the application in the field of water pollution collected in small scale plants. The suitability of a sorbent is determined by the cost, sorption performance and regeneration efficiency. The sorption capacity of resin for nickel metal ions was determined as 2.18 mmol/g. In order to develop a treatment system design it is also important to determine the best kinetic model, Elovich kinetic model, to describe the rate of nickel removal. Copyright © 2008 Society of Chemical Industry     

阳离子交换树脂催化的全乙酰基糖的合成

以CAT600阳离子交换树脂作为催化剂,醋酸酐既做溶剂又做乙酰化试剂,高效地进行了全乙酰基糖的合成。实验结果表明,所考察葡萄糖等8个糖类化合物在0.5 h内均能以较高的收率得到全乙酰基化的产物,产率达75%～95%。该方法具有高效、绿色、廉价、易于后处理等优点,有工业利用价值。