Kinetics of ethanol dehydrogenation into ethyl acetate

The kinetics of gas-phase dehydrogenation of ethanol into ethyl acetate over a copper-zinc-chromium catalyst has been investigated in a flow reactor at pressures of 10–20 atm and temperatures of 230–290°C. For the process occurring under kinetic control, the rate constants of two reactions and the adsorption constants of five components have been determined using the Langmuir-Hinshelwood model. A kinetic model has been developed for the process. This model provides means to design a reactor for dehydrogenation of ethanol into ethyl acetate in different regimes.     

Densities,excess molar volumes,and refractive indices of ethyl acetate and aromatic hydrocarbon binary mixtures

Densities, excess molar volumes, refractive indices, and changes in refractive index on mixing for (ethyl acetate  +  benzene, or methylbenzene, or ethylbenzene, or 1-4-dimethylbenzene, or 1-methylethylbenzene, or 1-3-5-trimethylbenzene, or 1-1-dimethylethylbenzene) have been determined atT =  298.15 K. The excess molar volumes and changes in refractive index have been fitted to Redlich–Kister polynomials. The π -electrons interactions of the benzene ring and the peculiar plate shape of the aromatic molecules are noticeably modified by the presence of the ethyl acetate molecules of a different nature. The intermolecular interactions are strongly modified and result in positive excess volumes except for toluene or p -xylene whose values are close to zero. The refractive indices were compared with calculated values using mixing rules proposed by several authors.     

Equilibrium desorption isotherms of water,ethanol, ethyl acetate,and toluene on a sodium smectite clay

Desorption isotherms for water, ethanol, ethyl acetate and toluene from a sodium smectite clay have been determined by both dynamic vapor sorption (DVS) measurements and Knudsen thermogravimetry (KTGA), at the exception of toluene that was measured only by the DVS method. The results obtained using these two methods were in satisfactory agreement, providing reliable insight into the desorption process, with certain lack of precision for ethyl acetate. The observed desorption behaviour suggests a liquid like phase at high volatile load, and a sorbed state in which molecules interact with the counter ions, at low volatile contents. However, the isotherms for water determined at various temperatures nearly superposed when plotted as a function of water activity, indicating the strength of the interactions in the clay–water system to remain of the same order of magnitude as that in bulk water, consistent with previous ab initio calculations.     

Phase behaviour of ethanol + water + ethyl acetate at 101.3 kPa

Must distillation processes simulation is a challenging task, due to the lack of thermodynamic interaction parameters and accurate studies of phase equilibria. The presence of polar substances, those different from ethanol and water, and their low concentrations make it very difficult to model industrial distillation. Several of the congeners are essential enological components of the organoleptic matrix. In this work, we are concerned with the study of phase behaviour of ethanol + water + ethyl acetate at 101.3 kPa, this being the third compound, the legal congener of the highest composition in common alcoholic distillation. The experimental results showed partial miscibility and four azeotropes into a complex medium. Group contribution models yield poor results. Disposable literature was compared and commented upon. The lack of experimental data in multicomponent alcoholic distillation mixtures and the low reliability of the group contribution methods suggest a prudent application to process simulation.     

Excess molar volumes of (ethyl formate or ethyl acetate + an isomer of hexanol) at 298.15 K

Excess molar volumes V_m^E were determined over the entire composition range at 298.15 K for ethyl formate or ethyl acetate + hexan-1-ol, +2-methylpentan-1-ol, +3-methylpentan-2-ol, +2-methylpentan-3-ol, +3-methylpentan-3-ol, +2-methylpentan-2-ol, +4-methyl-pentan-2-ol, and +hexan-2-ol. Excess volumes were determined from density measurements made with a vibrating-tube densimeter. The V_m^E values were all positive, decreasing with the n value of the ester: C_n?1H_2n?1CO₂C₂H₅.     

Contributions to the ethyl acetate application in residue analysis

Summary For the determination of pesticide residues 10 fruit and vegetable samples and 2 wheat samples with unknown spray history were extracted by the micro on-line extraction technique using the binary solvent system water + ethyl acetate as the extracting agent. The results of this proposed micro extraction were compared with already tested methods and it was found that the micro ethyl acetate method was equally effective. The reduction of solvents and chemical waste by miniaturization of analytical procedures is an important step for environmental protection.     

Contributions to the ethyl acetate application in residue analysis

Summary Atrazine was extracted from two weathered soil samples with the proposed micro extraction method using ethyl acetate as the extracting agent. The results were compared with other extraction methods tested. The proposed micro method was equally effective as the micro on-line method using acetone for the extraction and more effective than the Soxhlet extraction using acetone and methanol. Therefore, the proposed micro ethyl acetate method can be used for routine analysis.     

Preferential solvation of indomethacin and naproxen in ethyl acetate + ethanol mixtures according to the IKBI method

The preferential solvation parameters of indomethacin and naproxen in ethyl acetate + ethanol mixtures are derived from their thermodynamic properties by using the inverse Kirkwood–Buff integrals method. It is found that both drugs are sensitive to solvation effects, so the preferential solvation parameter, δx_EA,D, is negative in ethanol-rich and ethyl acetate-rich mixtures but positive in compositions from 0.36 to 0.71 in mole fraction of ethyl acetate. It is conjecturable that in ethanol-rich mixtures, the acidic interaction of ethanol on basic sites of the analgesics plays a relevant role in the solvation. The more solvation by ethyl acetate in mixtures of similar co-solvent compositions could be due to polarity effects. Finally, the slight preference of these compounds for ethanol in ethyl acetate-rich mixtures could be explained as the common participation of basic sites in both solvents and the acidic site of ethanol. Nevertheless, the specific solute–solvent interactions remain unclear.     

Mathematical modeling of cellulose conversion to ethanol by the simultaneous saccharification and fermentation process

Ethanol, a promising alternative fuel, can be produced by the simultaneous saccharification and fermentation (SSF) of lignocellulosic biomass, which combines the enzymatic hydrolysis of cellulose to glucose and the fermentation of glucose to ethanol by yeast in a single step.

A mathematical model that depicts the kinetics of SSF has been developed based on considerations of the quality of the substrate and enzyme, and the substrate-enzyme-microorganism interactions. Critical experimentation has been performed in conjunction with multiresponse nonlinear regression analysis to determine key model parameters regarding cell growth and ethanol production. The model will be used for rational SSF optimization and scale-up.

     

Mathematical modeling of butadiene rubber synthesis process on neodymium-containing catalyst system

The synthesis of butadiene rubber mediated by a lanthanide catalyst system based on neodymium(III) chloride in a batch reactor was mathematically modeled. The mechanism of the process was identified and the rate constants of various reaction steps were determined. It was found that chain transfer reactions with different rate constants have an effect on the molecular-mass characteristics of butadiene rubber.     

2-vinyloxy ethyl phthalimide polymerization initiated by 1-(isobutoxy) ethyl acetate in the presence of ethyl aluminum dichloride and either ethyl acetate or ethyl benzoate

2-Vinyloxy ethyl phthalimide (ImVE) was polymerized using 1-(isobutoxy) ethyl acetate as the initiator in the presence of ethyl aluminum dichloride and either ethyl acetate or ethyl benzoate. The resulting polymers have a narrow molecular weight distribution, and their molecular weight can be controlled within a narrow range by varying the monomer and initiator concentrations. Diblock copolymers with n-butyl vinyl ether can also be formed. The behavior of the polymerization is consistent with a living cationic mechanism. A brief comparison of the title system with other initiating systems is also presented. © 1996 John Wiley & Sons, Inc.     

Effect of 1,2-propanediol on the vapor-liquid equilibria of the ethyl acetate + ethanol system at 101.3 kPa

Vapor-liquid equilibrium (VLE) data for the system ethyl acetate + ethanol in the presence of 1,2-propanediol at concentrations of 0%, 20%, 30%, and 40% by weight were measured at 101.3 kPa. The experimental VLE data of the ternary system ethyl acetate + ethanol + 1,2-propanediol were correlated by the Margules, Wilson, NRTL, and UNIQUAC liquid models. The relative volativities of ethyl acetate with respect to ethanol were also determined. The results of the investigation indicate the disappearance of the binary azeotrope between ethyl acetate and ethanol at the solvent concentrations studied in this work.     

Sonochemically prepared Pt/CeO2 and its application as a catalyst in ethyl acetate combustion

Highly dispersed Pt nanoparticles were incorporated in CeO2 nanopowders by an ultrasound-assisted reduction procedure. The activity of the Pt/CeO2 catalysts was studied in the reaction of the ethyl acetate combustion, and complete conversion was achieved at low temperature. It was demonstrated that the higher dispersion of the CeO2 support, the better the performance of the Pt/CeO2 catalysts. The catalysts were characterized by XRD, TEM, HRTEM, EDX, BET, and XPS. The homogeneous incorporation of 2-4 nm Pt nanoparticles into the interparticle distance of the CeO2 nanopowders was demonstrated. The advantage of the sonochemical method for catalyst preparation, in comparison with the traditional incipient wetness impregnation, was explained as the result of the homogeneity and better dispersion of the active metal phase obtained by ultrasound irradiation.     

Individual and simultaneous enzymatic determination of ethanol and acetaldehyde in wines by flow injection analysis

The individual and simultaneous enzymatic determination of ethanol and acetaldehyde in wine by flow injection analysis is described. Individual determinations of 0.002–0.016% (v/v) ethanol or 1.0–8.0 μg ml^?1 acetaldehyde with r.s.d. 0.7% and 0.5%, respectively, are done with a single-beam spectrophotometer, based on the use of alcohol dehydrogenase and aldehyde dehydrogenase. A diode-array detector and dual reagent injections are used for the simultaneous determination of the two compounds. The errors are 〈 3.5% and 〈 2.0% for ethanol and acetaldehyde, respectively, when the method is applied to wine samples.     

相转移催化剂对催化柴油氧化脱硫作用的数学模型

经过顺序氧化反应动力学方程、相转移催化剂强化作用数学模型方程和萃取相平衡方程的推导,确定了催化柴油氧化萃取脱硫数学模型方程。研究表明,呈指数函数形式的相转移催化剂作用数学模型具有较高的计算精度。通过模型参数估值确定了氧化速率常数的频率因子和活化能、相平衡常数、相转移催化剂作用模型参数,建立了脱硫率数学模型。模型预测显示,柴油脱硫率随着氧化时间延长呈先提高后降低的趋势;氧化时间较短时,柴油脱硫率随相转移催化剂用量提高而增大,但氧化时间较长时的情况相反;柴油脱硫率随着氧化溶液体积分数增大或萃取剂与油比增大均呈提高的趋势。     

The variation of viscosity, refractive indices, compressibility, intermolecular free length, and excess molar volume of the acetophenone—ethyl acetate solutions at 303.15–323.15 K

Densities, viscosities, refractive indices and ultrasonic velocities of the binary mixtures of acetophenone with ethyl acetate were measured over the entire mole fractions at 303.15, 313.15, and 323.15 K. From the experimental results, excess molar volumes V ^E, viscosity deviation ??_??, refractive index deviation ??n _D , deviations in isentropic compressibility ???? _s and excess intermolecular free length ??L _f are calculated. The viscosity values were fitted to the models of Krishnan-Laddha and McAllister. The thermophysical properties under study were fit to the Jouyban-Acree model. The excess values were correlated using Redlich-Kister polynomial equation to obtain their coefficients and standard deviations. The data obtained fitted with the values correlated by the corresponding models very well. The results are interpreted in terms of molecular interactions occurring in the solution.     

Thermochemistry of ethyl acetate solvation in the 1-octanol-N,N-dimethylformamide system

The thermal effects of ethyl acetate (EtOAc), 1-octanol (OctOH), and N,N-dimethylformamide (DMF) solution in a OctOH-DMF model system were measured using a calorimeter of variable temperature with an isothermal shell at 298 K. The standard enthalpies of solution and ester transfer from an alcohol to a binary mixture, and partial mole enthalpies of mixed solvent components were determined. The state of non-electrolyte molecules in OctOH-DMF and OctOH-DMF-EtOAc systems were studied using extended coordination model. It was found that the binary solvent is subjected to microclusterization, since the fraction of the single-type molecules in the solvation sphere of both components of a mixture is significantly higher than in the liquid phase volume. The conclusion was drawn that in the triple system, the ethyl acetate solvation sphere in the whole range of compositions is significantly enriched with amide owing to stronger esteramide dipole-dipole interaction.