Group contribution modeling of activity coefficients in associating solutions containing water, alcohols and carboxylic acids

A modified UNIFAC group contribution model for the prediction of activity coefficients in associating solutions (A-UNIFAC) is applied to calculate phase equilibria in binary and ternary mixtures of associating and non-associating species, including alcohols, water, carboxylic acids, esters, alkanes, aromatic hydrocarbons and alkyl chlorides. Self- and cross-association in these mixtures is adequately described by the definition of a single hydrogen-bonding group. The new model is able to give good predictions of vapor-liquid equilibria, liquid-liquid equilibria and infinite dilution activity coefficients, using a single set of group-interaction parameters.The authors are grateful to the Argentinian National Research Council (CONICET) and to Universidad Nacional del Sur (UNS) for financial support. M.O. Ferreira acknowledges financial support from the PRAXIS program, FCT, Lisbon, Portugal

Equations of State in Chemical Reacting Systems

Phase and chemical equilibrium calculations are essential for the design of processes involving chemical transformations. Even in the case of reactions that cannot reach chemical equilibrium, the solution of this problem gives information on the expected behaviour of the system and the potential thermodynamic limitations. There are several problems in which the simultaneous calculation of chemical and phase behaviour is mandatory. This is the case, for example, of reactive distillations where phase separation is used to shift chemical equilibrium. Also, the calculation of gas and solid solubility in liquids of high dielectric constants requires at times the resolution of chemical equilibrium between the different species that are formed in the liquid phase. Several algorithms have been proposed in the literature to solve the complex non-linear problem; however, proper thermodynamic model selection has not received much attention. In recent times, the use of supercritical solvents has emerged as an important technique to improve rates and selectivities in diffusion-controlled reactions. Phase behaviour near the critical point of mixtures is very sensitive to process operating conditions and mixture compositions. The selection and design of the appropriate phase conditions to exploit process potential require thermodynamic models able to deal with highly asymmetric mixtures involving permanent gases, supercritical solvents and non-volatile substrates. This chapter presents a phase equilibrium engineering approach to analyze the phase behaviour of chemical reacting systems. The use of group contribution equations of states in these systems is discussed. The main advantage of these models is that they have predictive capability for compounds that were not included in the parameterization process. The lack of equilibrium data in reactive mixtures is quite common; therefore, group contribution methods allow designers to gain knowledge on the changes in phase behaviour as the reaction proceeds.Fil: Pereda, Selva. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Planta Piloto de Ingeniería Química. Universidad Nacional del Sur. Planta Piloto de Ingeniería Química; ArgentinaFil: Brignole, Esteban Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Planta Piloto de Ingeniería Química. Universidad Nacional del Sur. Planta Piloto de Ingeniería Química; ArgentinaFil: Bottini, Susana Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Fundamentals of supercritical fluid technology

This chapter deals with fundamentals of supercritical fluid extraction. Considering first the typical phase diagrams of high pressure systems. Thereafter the application of supercritical fluids to separations is illustrated with alcohol extraction and dehydration with hot propane, extraction of vegetable oils with non flammable solvents and fractionation of fish oils and essential oils with carbon dioxide. Also the removal of chemicals using supercritical fluids is considered. Finally the subject of phase equilibrium engineering of supercritical reactors is developed.Fil: Pereda, Selva. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Planta Piloto de Ingeniería Química. Universidad Nacional del Sur. Planta Piloto de Ingeniería Química; ArgentinaFil: Bottini, Susana Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Planta Piloto de Ingeniería Química. Universidad Nacional del Sur. Planta Piloto de Ingeniería Química; ArgentinaFil: Brignole, Esteban Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Planta Piloto de Ingeniería Química. Universidad Nacional del Sur. Planta Piloto de Ingeniería Química; Argentin

Supercritical fluids and phase behavior in heterogeneous gas-liquid catalytic reactions

Gas-liquid catalyzed reactions carried out in a supercritical medium take advantage of the high reaction rates and improved selectivities that can be achieved by having reactants and products in a homogeneous phase. In this work, the phase behavior of several supercritical reactions are analyzed and the selection of adequate solvents is discussed. The reactions studied include the hydrogenation of terpenic compounds and unsaturated aldehydes, and the hydroformylation of hydrocarbons to produce aldehydes. Recent experimental results from the literature on the kinetics and selectivities of these reactions are discussed on the basis of the phase equilibrium scenario under the reaction conditions.Fil: Pereda, Selva. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Planta Piloto de Ingeniería Química. Universidad Nacional del Sur. Planta Piloto de Ingeniería Química; ArgentinaFil: Bottini, Susana Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Planta Piloto de Ingeniería Química. Universidad Nacional del Sur. Planta Piloto de Ingeniería Química; ArgentinaFil: Brignole, Esteban Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Planta Piloto de Ingeniería Química. Universidad Nacional del Sur. Planta Piloto de Ingeniería Química; Argentin

Infinite dilution activity coefficients in mono-, di-, and tripalmitin and palmitic acid

Infinite dilution activity coefficients of several organic solutes in mono-, di-, and tripalmitin and in palmitic acid were measured by gas chromatography, at temperatures between 353 K and 373 K. The solutes include hydrocarbons, chlorinated hydrocarbons, and alcohols. The UNIFAC group contribution model and Flory's combinatorial model, with the addition of a regular solution residual term, were used to correlate the experimental data.Fil: Foco, Gloria Margarita. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Planta Piloto de Ingeniería Química. Universidad Nacional del Sur. Planta Piloto de Ingeniería Química; ArgentinaFil: Bermudez, A.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Planta Piloto de Ingeniería Química. Universidad Nacional del Sur. Planta Piloto de Ingeniería Química; ArgentinaFil: Bottini, Susana Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Planta Piloto de Ingeniería Química. Universidad Nacional del Sur. Planta Piloto de Ingeniería Química; Argentin

Advances in phase equilibrium engineering of supercritical reactors

This review summarizes the advances made in the last decade in understanding the effect of phase conditions in the performance of supercritical reactors and in the control of process outputs. The study covers heterogeneous-catalyzed and non-catalytic supercritical reactions and shows the experimental and modeling tools that have been applied to address the problem of keeping reactants and products in a homogeneous phase. © 2008 Elsevier B.V. All rights reserved.Fil: Pereda, Selva. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Planta Piloto de Ingeniería Química. Universidad Nacional del Sur. Planta Piloto de Ingeniería Química; ArgentinaFil: Brignole, Esteban Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Planta Piloto de Ingeniería Química. Universidad Nacional del Sur. Planta Piloto de Ingeniería Química; ArgentinaFil: Bottini, Susana Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Planta Piloto de Ingeniería Química. Universidad Nacional del Sur. Planta Piloto de Ingeniería Química; Argentin

Effect of phase behavior in the hydrogenation of triglycerides under supercritical and near-critical propane

Sunflower oil was hydrogenated in a stirred-batch unit, using supercritical and near-critical propane as solvent, and Pd/γ-Al2O3 catalyst. The effect of the phase behavior on the reaction performance is analyzed. The transition from homogeneous to heterogeneous conditions showed no effect on the activity and selectivity of the reaction. These results point to an unrestricted availability of hydrogen at the catalyst surface. A comparison is made between fluid-solid mass transfer coefficients in stirred-batch and continuous fixed-bed reactors.Fil: Piqueras, Cristian Martin. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Planta Piloto de Ingeniería Química. Universidad Nacional del Sur. Planta Piloto de Ingeniería Química; ArgentinaFil: Damiani, Daniel Eduardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Planta Piloto de Ingeniería Química. Universidad Nacional del Sur. Planta Piloto de Ingeniería Química; ArgentinaFil: Bottini, Susana Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Planta Piloto de Ingeniería Química. Universidad Nacional del Sur. Planta Piloto de Ingeniería Química; Argentin

Sunflower oil hydrogenation on Pd/Al2O3 catalysts in single-phase conditions using supercritical propane

Several Pd catalysts were prepared on α and γ alumina using palladium acetylacetonate and palladium nitrate as a precursor. The characterization of these catalysts by H2 chemisorption, XRD and TEM microscopy confirm the presence of different dispersed metallic particles from 1.9 to 12.1 nm. These catalysts were tested in the sunflower oil hydrogenation under supercritical conditions using propane as solvent and 5% mol of hydrogen concentration. The well-known Weisz-Prater criterion was used to determine the extent of mass transport phenomena. While hydrogen mass transport was found free from limitations, oil transport had limitations in some experiments. The reaction is moderately structure sensitive since the turnover number decreases 3 times as the exposed metal percentage (metal dispersion) increases from 9 to 60%. An influence on the selectivities to trans isomers, monounsaturated and saturated fatty acids was found when the metallic particle size was decreased. These results are explained by the high adsorption strength of the high-unsaturated fatty acids onto the small particles and the promotion of a "shunt" reaction from linoleic to saturated compounds. © 2006 Elsevier B.V. All rights reserved.Fil: Piqueras, Cristian Martin. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Planta Piloto de Ingeniería Química. Universidad Nacional del Sur. Planta Piloto de Ingeniería Química; ArgentinaFil: Bottini, Susana Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Planta Piloto de Ingeniería Química. Universidad Nacional del Sur. Planta Piloto de Ingeniería Química; ArgentinaFil: Damiani, Daniel Eduardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Planta Piloto de Ingeniería Química. Universidad Nacional del Sur. Planta Piloto de Ingeniería Química; Argentin

Phase equilibrium data on binary and ternary mixtures of methyl palmitate, hydrogen and propane

The hydrogenolysis of fatty acid methyl esters (FAME) to obtain fatty alcohols, is a catalytic, multiphase reaction. Reaction rates can be greatly increased by using a supercritical solvent to bring the reactive mixture into a single homogeneous phase. Knowledge of the corresponding phase equilibria is a prerequisite in order to find the homogeneous region and to determine the most favorable conditions for the hydrogenation process. This paper reports experimental phase equilibrium data on binary and ternary mixtures of methyl palmitate, hydrogen and propane. A temperature region between 360 and 450 K, and pressures up to 15 MPa were covered.Fil: Rovetto, Laura Jorgelina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Planta Piloto de Ingeniería Química. Universidad Nacional del Sur. Planta Piloto de Ingeniería Química; ArgentinaFil: Bottini, Susana Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Planta Piloto de Ingeniería Química. Universidad Nacional del Sur. Planta Piloto de Ingeniería Química; ArgentinaFil: Peters, Cornelis J.. Delft University of Technology; Países Bajo

Application of a group contribution equation of state to model the phase behavior of mixtures containing alkanes and ionic liquids

In this work, the group contribution equation of state (GC-EoS) of Skjold-Jørgensen was used to model the phase behavior of mixtures of alkanes with different members of the homologous family 1-alkyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide, [x-Mpyr][NTf2] ionic liquids. Pure group parameters for the ionic liquid functional group (MpyrNTf2) and interaction parameters between this group and the paraffin main group (sub-groups CH3 and CH2) were obtained from activity coefficients at infinite dilution found in literature for binary mixture {alkane + [x-Mpyr][NTf2] ionic liquid}. The GC-EoS of Skjold-Jørgensen, extended with these new parameters, was applied to predict with satisfactory results the phase behavior of binary mixtures {alkane + [x-Mpyr][NTf2]}. In order to evaluate the GC-EoS performance in the prediction of liquid?liquid equilibria (LLE), experimental LLE data for binary mixtures {hexane, or heptane, or octane, or nonane, or decane +1-butyl-1-ethylpyrrolidinium bis(trifluoromethylsulfonyl) imide, [BMpyr][NTf2]} were determined from T = (293.15 to 333.15)KFil: González, Emilio J.. Universidad de Porto; PortugalFil: Bottini, Susana Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Bahía Blanca. Planta Piloto de Ingeniería Química (i); Argentina. Universidad Nacional del Sur; ArgentinaFil: Macedo, Eugénia Macedo. Universidad de Porto; Portuga