Group Contribution With Association Equation Of State Research Articles

GCA-EOS extension to mixtures of phenol ethers and derivatives with hydrocarbons and water

Anisol and its derivatives are typically used in the flavoring and fragrance industry, and they are also considered as additives for fuels and solvents for separation processes. Despite their growing importance, due to the development of biomass conversion routes, only few authors have modeled their phase behavior, which is required to assess industrial applications. In this work, we extend the Group Contribution with Association Equation of State (GCA-EOS) to multiphase equilibria of phenol ethers. We investigate pure anisole and its derivatives, as well as their mixtures with linear and cyclic alkanes, alkenes, aromatic hydrocarbons, and water. To fit the model parameters and assess its predictive capacity, we assemble an experimental database with the vapor pressure of 8 phenol ethers and 283 binary equilibrium datapoints. The parameterization procedure aims to reduce the required number of binary interaction parameters, avoiding to over correlate the model. The results show that GCA-EOS predicts the pure vapor pressure data with an average deviation of 3%, as well as the VLE of binary mixtures with similar accuracy. On the other hand, the model is also able to describe the mutual solubility of methoxy aromatic compounds with water.

Modeling of Trifluoromethane (R-23) or Hexafluoroethane (R-116) and Alkane Binary Mixtures using the Group-Contribution with Association Equation of State

The group-contribution with association equation of state (GCA-EOS) has been applied to represent the phase behavior of binary systems containing either trifluoromethane (R-23) or hexafluoroethane (R-116) with alkanes. The model was successfully fitted to selected literature data, which also formed part of a study into the use of these refrigerants as supercritical fluid extraction solvents. The tuned model was tested against the available experimental data covering the homologous series of C2 to C11 alkanes with either R-23 or R-116, at temperatures between 193 and 343 K and at pressures of up to 60 MPa. The tuned model provided accurate predictions of the phase behavior of these systems, including the ability to identify the carbon number of the alkane in the system at which the phase equilibria transformation occurred. The comparison of the model to the experimental data was excellent, with absolute average relative deviations of between 1% and 5% for both pressure and vapor phase compositions.

Reprint of “Experimental measurement and modeling of quinizarin solubility in pressurized hot water”

In the field of natural products, anthraquinones are an important category of secondary metabolites present in various vegetable species. They are highly bioactive compounds, potentially useful for therapeutic applications, as antiviral, anti-bacterial and anti-cancer agents. Extraction processes using pressurized hot water offer an environmentally friendly alternative to traditional extraction and purification methods applied to anthraquinone-containing plants. Knowledge on high-pressure phase equilibria of anthraquinone+solvent mixtures is required to evaluate the potentiality of these processes. The need is for both, experimental data and thermodynamic models that are able to predict phase boundaries at different process conditions. In this work, the solubility of 1,4-dihydroxy-9,10-anthraquinone (quinizarin) in pressurized hot water has been measured, using a simple and reliable dynamic method. For the binary quinizarin +H2O, the measurements were performed at (333, 353, 373, 393, 413, 443, 463) K and pressures of (30, 60 and 90) bar. The group-contribution with association equation of state (GCA-EOS), with the definition of a cyclic ketone functional group (CyCO) was used to calculate solid-liquid equilibria of binary mixtures of anthraquinones with pressurized hot water. This model was able to give a good representation of the solubility behaviour of quinizarin in water.

Experimental measurement and modeling of quinizarin solubility in pressurized hot water

In the field of natural products, anthraquinones are an important category of secondary metabolites present in various vegetable species. They are highly bioactive compounds, potentially useful for therapeutic applications, as antiviral, anti-bacterial and anti-cancer agents. Extraction processes using pressurized hot water offer an environmentally friendly alternative to traditional extraction and purification methods applied to anthraquinone-containing plants. Knowledge on high-pressure phase equilibria of anthraquinone+solvent mixtures is required to evaluate the potentiality of these processes. The need is for both, experimental data and thermodynamic models that are able to predict phase boundaries at different process conditions. In this work, the solubility of 1,4-dihydroxy-9,10-anthraquinone (quinizarin) in pressurized hot water has been measured, using a simple and reliable dynamic method. For the binary quinizarin +H2O, the measurements were performed at (333, 353, 373, 393, 413, 443, 463) K and pressures of (30, 60 and 90) bar. The group-contribution with association equation of state (GCA-EOS), with the definition of a cyclic ketone functional group (CyCO) was used to calculate solid-liquid equilibria of binary mixtures of anthraquinones with pressurized hot water. This model was able to give a good representation of the solubility behaviour of quinizarin in water.

Multiphase Equilibria Modeling with GCA-EoS. Part I: Carbon Dioxide with the Homologous Series of Alkanes up to 36 Carbons

The Group Contribution with Association Equation of State (GCA-EoS) has been successfully applied to represent the global phase behavior of carbon dioxide mixtures with alkanes. Using a single set of parameters, the model is able to predict vapor–liquid and liquid–liquid equilibria of binary mixtures not included in the parametrization procedure. Special emphasis was set on describing the transformation between types of fluid phase behavior to reduce the jeopardy of predicting incorrect liquid split. This family of binary systems has been investigated in previous works; however, this is the first time that GCA-EoS was shown to be able to represent the transformation between types of phase behavior as the length of the alkyl chain increases. The model was tested against an experimental database covering C3–C36 alkanes, temperatures from 210 to 660 K, and pressures up to 400 bar. The wide range of conditions and the parametrization strategy are keys to develop a robust thermodynamic tool for predicting mult...

Thermodynamic model for biomass processing in pressure intensified technologies

Pressure intensified technologies have a great potential in the context of biomass refining. A thermodynamic model able to predict phase behavior of typical mixtures found in biomass processing technologies, containing for instance hydrocarbons, organo-oxygenated compounds and water, is required for the development of a biorefinery process simulator. Moreover, the design of particular fuel/biofuel blends also requires the support of a thermodynamic model to predict the properties of the final products. These types of mixtures are highly non-ideal due to the presence of association and solvation effects. It has already been proved that the Group Contribution with Association Equation of State (GCA-EoS) is able to predict the complex phase behavior of mixtures containing natural products and biofuels. In the last few years, several contributions agree that 2,5-dimethylfuran has a great potential as a sugar-derived fuel additive. In this work, as a case study, we extend the GCA-EoS to represent the phase equilibria of furan derivatives with hydrocarbons and alcohols. In addition, we show that the GCA-EoS is able to predict, based on the performed parameterization, high pressure data of 2,5-hydroxymethylfurfural solubility in CO2 and ethanol as co-solvent.

Supercritical production and fractionation of fatty acid esters and acylglycerols

The production of biodiesel or fatty acid esters (FAE) from lipids with supercritical methanol (scMeOH) has gained interest in the last decade because it allows the direct transesterification of crude oils and fats. The reaction should be carried out above 593K in order to achieve complete conversion. When milder conditions are set, also monoglycerides (MG) and diglycerides (DG), together with glycerol, are obtained as byproducts of the transesterification process. Acylglycerols are common food emulsifiers and surface active agents in many industrial cleaning products.The main goal of this work is to study the fractionation of FAE and acylglycerols by using CO2 as a green solvent. Mixtures of FAE, MG and DG were produced by partial transesterification of sunflower oil with scMeOH in a temperature range of 556–605K and using different methanol to oil molar ratios (between 20 and 50). Then, experimental data on phase equilibria of reaction products+CO2 were measured at 298K and 313K in a variable volume cell with windows. The measured data were used to test the predictive capability of the Group Contribution with Association Equation of State (GCA-EoS). The acylglycerols can be purified by near critical extraction of the FAE with CO2. The simulation of the extraction process working with CO2, in liquid or supercritical state, gives a concentration of acylglycerols higher than 99.8wt.% in the raffinate phase with a concentration of FAE above 97wt.% in the extract phase.

Minimizing Costs in Near-Critical Bioethanol Extraction and Dehydration Processes

In the present work, we propose a model-based cost optimization for three capacities of bioethanol extraction–dehydration plants with supercritical propane. We consider alternative integration schemes between process streams as different nonlinear programming problems (NLP) for energy minimization. In particular, we analyze integration between a heat pump option for the top vapor of the first distillation column with the beer column reboiler, which can provide reduction in total energy consumption, as well as lower final product cost. Capital and operating costs were evaluated for the analyzed schemes. Thermodynamic predictions are performed with an upgraded group contribution with association equation of state (GCA-EOS). We demonstrate that ethanol dehydration with supercritical propane can be a sustainable alternative that is energetically and economically competitive with other technologies.

Phase equilibrium modeling of triglycerides in supercritical fluids

To design a reactor and separator for a supercritical biodiesel process, phase equilibria of multi-component mixtures in supercritical fluids should be determined using group contribution with association equation of state (GCA-EOS) as a thermodynamics method. The model is considered for two systems of reactants and products. System 1 is comprised of methanol and triglycerides from two sources (palm and Jatropha oils); and System 2 is unconverted methanol, FAME (product) and glycerol (by-product). Pressure and temperature diagrams were developed at different mole fraction of methanol ( x MeOH). As x MeOH increased, the critical temperature ( T c) and pressure ( p c) increased. The increasing temperature causes the immiscibility region and the amount of methanol at the plait point to decrease. The maximum plait point pressure was observed at 19.20 MPa for palm and 19.33 MPa for Jatropha oil systems.

Modeling alcohol + water + hydrocarbon mixtures with the group contribution with association equation of state GCA-EoS

The growing interest on first- and second-generation biofuels requires the development of thermodynamic tools with predictive capacity for mixtures containing a wide variety of organo-oxygenated compounds, water and hydrocarbons. Modeling this type of mixtures is challenging due to the presence of association and solvation effects. In this work, we present a revision of the group contribution with association equation of state (GCA-EoS) parameters, with the purpose of extending and improving the predictive capacity of the model for systems containing water, alcohols and hydrocarbons.

Solubility of hydrocarbons in water: Experimental measurements and modeling using a group contribution with association equation of state (GCA-EoS)

In this communication, new experimental data on the solubility of n-hexane, cyclo-hexane and iso-octane in pure water are reported. The data have been measured using a static-analytic technique that takes advantage of a Rolsi™ sampling device in the temperature range of 298–353 K and at pressures up to 0.5 MPa. The experimental data measured in this work at 298 K have been compared with some selected data from the literature and good agreement is found. A group contribution plus association equation of state, namely the GCA-EoS, is used to model the phase equilibrium of water + hydrocarbon (C 2 to n-C 6, cy-C 6, i-C 4 and i-C 8) system. The predictions of the model are found in good agreement with the experimental data measured in this work and some selected data from the literature.

Phase Equilibria in Ternary Mixtures of Methyl Oleate, Glycerol, and Methanol

Transesterification reactions are common in the production of some important chemicals, such as biodiesel and mono- and diglycerides. Knowledge of the phase equilibrium conditions of the reactive mixture is essential to explore possible operating conditions for the reactor and the downstream separation process. In this work, liquid—liquid and vapor—liquid—liquid equilibrium data have been measured for the ternary system methyl oleate—methanol—glycerol, at temperatures between 313 and 393 K. The group contribution with association equation of state (GCA-EOS) and the A-UNIFAC model were applied to represent the phase equilibria of this ternary system. Self-association in glycerol and methanol and cross-association with methyl esters were taken into account.

Phase‐equilibrium modeling in the hydrogenation of vegetable oils and derivatives

AbstractThe main tool needed to carry out phase‐equilibrium engineering of a given process is an adequate thermodynamic model adjusted to the range of process operating conditions of the working system. In the present work the Group Contribution with Association Equation of State (GCA‐EoS) is used to model the phase behavior of reacting mixtures typical of the hydrogenation of vegetable oils and derivatives at supercritical or high‐pressure conditions.

Application of the GCA-EoS model to the supercritical processing of fatty oil derivatives

The group-contribution with association equation of state (GCA-EoS) is applied to represent high-pressure phase equilibria in mixtures of supercritical gases (carbon dioxide, propane) with fatty oil derivatives, such as mono- and di-glycerides, fatty acids and fatty acid esters. Association effects in these mixtures are described by a group-contribution approach using three different association groups: the hydroxyl group, the acid group and the ester group. Satisfactory predictions of vapor–liquid equilibria, liquid–liquid equilibria and γ ∞ of binary and ternary mixtures of high-molecular weight triacyglycerides and their derivatives with carbon dioxide or propane are obtained. It is shown that the GCA-EoS is a powerful engineering tool for the design and optimization of extraction and fractionation processes of fatty oil derivatives with supercritical fluids.

Modelling of phase equilibria for associating mixtures using an equation of state

In the present work, the group contribution with association equation of state (GCA-EoS) is extended to represent phase equilibria in mixtures containing acids, esters, and ketones, with water, alcohols, and any number of inert components. Association effects are represented by a group-contribution approach. Self- and cross-association between the associating groups present in these mixtures are considered. The GCA-EoS model is compared to the group-contribution method MHV2, which does not take into account explicitly association effects. The results obtained with the GCA-EoS model are, in general, more accurate when compared to the ones achieved by the MHV2 equation with less number of parameters. Model predictions are presented for binary self- and cross-associating mixtures.

Thermodynamic modeling, synthesis and optimization of extraction — dehydration processes

The synthesis problem of a new separation operation (dehyextraction) with near critical fluids is formulated as a mixed integer nonlinear programming (MINLP) problem. The key separation properties of the dehyextraction process are predicted by the group contribution with association equation of state (GCA-EOS) that supports property predictions of a rigorous process simulator. The simulator is integrated to a MINLP optimization program. Optimal schemes and operating conditions are determined for different aqueous solutions in a wide range of oxychemical compositions. A detailed study for the recovery and dehydration of ethanol, 2-propanol and acetone and mixtures of these solutes from aqueous solutions using supercritical gases as propane, propylene and isobutane is presented.