Manuela Artal

Excess enthalpies and molecular interactions in solutions of 1-fluoroalkanes in alkanes, benzene or tetrachloromethane. A group contribution (DISQUAC) study

Molar excess enthalpies HE at 298.15 K and atmospheric pressure were determined for 12 binary liquid mixtures, 1-fluoropentane, 1-fluorohexane, or 1-fluorononane + a non-polar solvent (hexane, cyclohexane, benzene, or tetrachloromethane) and were interpreted by the DISQUAC group contribution model. 1-Fluoroalkane + n-alkane mixtures are characterized by two types of groups or contact surfaces, fluorine (F) and alkane (CH3, CH2), the remaining mixtures by the additional contact surfaces of the solvents (C6H12 C6H6, or CCl4). The interchange energies, entirely dispersive, of the alkane-solvent contacts were determined independently from the study of solvent-alkane mixtures. The dispersive F-alkane parameters were assumed to equal the parameters of perfluoroalkanes + n-alkanes. The shape of the HE curves of 1-fluorolkane + polarizable solvent (C6H6, CCl4) mixtures are best reproduced by the model when the quasi-chemical F-solvent parameters are assumed to equal zero. The quasi-chemical F-alkane (the same for n-alkanes and cyclohexane) and the dispersive F-solvent parameters were estimated in this work. The 1-fluoroalkane solutions in C6H6 or CCl4 exhibit the characteristic features of polar solute + polarizable solvent mixtures, viz., the deviations from the ideality are less positive than in alkanes and the experimental HE curves are strongly asymmetrical.

Accurate values of some thermodynamic properties for carbon dioxide, ethane, propane, and some binary mixtures.

Quasicontinuous PρT data of CO(2), ethane, propane, and the [CO(2) + ethane] mixture have been determined along subcritical, critical, and supercritical regions. These data have been used to develop the optimal experimental method and to determine the precision of the results obtained when using an Anton Paar DMA HPM vibrating-tube densimeter. A comparison with data from reference EoS and other authors confirm the quality of our experimental setup, its calibration, and testing. For pure compounds, the value of the mean relative deviation is MRD(ρ) = 0.05% for the liquid phase and for the extended critical and supercritical region. For binary mixtures the mean relative deviation is MRD(ρ) = 0.70% in the range up to 20 MPa and MRD(ρ) = 0.20% in the range up to 70 MPa. The number of experimental points measured and their just quality have enable us to determine some derivated properties with satisfactory precision; isothermal compressibilities, κ(T), have been calculated for CO(2) and ethane (MRD(κ(T)) = 1.5%), isobaric expasion coefficients, α(P), and internal pressures, π(i), for CO(2) (MRD(α(P)) = 5% and MRD(π(i)) = 7%) and ethane (MRD(α(P)) = 7.5% and MRD(π(i)) = 8%). An in-depth discussion is presented on the behavior of the properties obtained along subcritical, critical, and supercritical regions. In addition, PuT values have been determined for water and compressed ethane from 273.19 to 463.26 K up to pressures of 190.0 MPa, using a device based on a 5 MHz pulsed ultrasonic system (MRD(u) = 0.1%). With these data we have calibrated the apparatus and have verified the adequacy of the operation with normal liquids as well as with some compressed gases. From density and speed of sound data of ethane, isentropic compressibilities, κ(s), have been obtained, and from these and our values for κ(T) and α(P), isobaric heat capacities, C(p), have been calculated with MRD(C(p)) = 3%, wich is within that of the EoS.

Excess enthalpies of (N,N-dimethylformamide or N,N-dimethylacetamide + hexane or benzene or toluene or p-xylene or mesitylene)

The excess molar enthalpies HEm of (N,N-dimethylformamide or N,N-dimethylacetamide + hexane, at 313.15 K, or + benzene or toluene or p-xylene or mesitylene, at 303.15 K) have been determined experimentally as a function of mole fraction. (N,N-dialkylamide + hexane) shows partial miscibility. HEm is positive except for (N,N-dimethylformamide + benzene). HEm(N,N-dimethylamide + an aromatic hydrocarbon) show a remarkable exothermic effect relative to hexane mixtures.

Influence of Methane in CO2 Transport and Storage for CCS Technology

CO(2) Capture and Storage (CCS) is a good strategy to mitigate levels of atmospheric greenhouse gases. The type and quantity of impurities influence the properties and behavior of the anthropogenic CO(2), and so must be considered in the design and operation of CCS technology facilities. Their study is necessary for CO(2) transport and storage, and to develop theoretical models for specific engineering applications to CCS technology. In this work we determined the influence of CH(4), an important impurity of anthropogenic CO(2), within different steps of CCS technology: transport, injection, and geological storage. For this, we obtained new pressure-density-temperature (PρT) and vapor-liquid equilibrium (VLE) experimental data for six CO(2) + CH(4) mixtures at compositions which represent emissions from the main sources in the European Union and United States. The P and T ranges studied are within those estimated for CO(2) pipelines and geological storage sites. From these data we evaluated the minimal pressures for transport, regarding the density and pipelines capacity requirements, and values for the solubility parameter of the mixtures, a factor which governs the solubility of substances present in the reservoir before injection. We concluded that the presence of CH(4) reduces the storage capacity and increases the buoyancy of the CO(2) plume, which diminishes the efficiency of solubility and residual trapping of CO(2), and reduces the injectivity into geological formations.

Temperature and pressure dependence of the volumetric properties of binary liquid mixtures containing 1-propanol and dihaloalkanes

Densities of 1-propanol + dibromomethane, or +bromochloromethane, or +1,2-dichloroethane, or +1-bromo-2-chloroethane binary mixtures were measured at 288.15, 298.15 and 308.15 K, over the entire composition range. Thermal expansion coefficients, α, and excess molar volumes, , were calculated. Moreover, densities at 298.15 K and pressures up to 2 × 107 Pa were determined for the same mixtures. Isothermal compressibilities, κT, of the pure liquids and their mixtures were obtained.

Volumetric behavior of the {CO2 (1) + C2H6 (2)} system in the subcritical (T = 293.15 K), critical, and supercritical (T = 308.15 K) regions.

The volumetric behavior for the {CO2 (1) + C2H6 (2)} system has been studied. Density measurements of {CO2 (1) + C2H6 (2)} binary mixtures at 293.15 and 308.15 K, at several pressures and compositions, and density measurements for infinitely dilute solutions at 304.21 and 308.15 K were carried out using an Anton Paar DMA 512-P vibrating-tube densimeter calibrated with the forced path mechanical calibration model. The mean relative standard deviation of density, s(rho)(r), was estimated to be better than 0.1%, and the uncertainties in temperature and pressure were estimated as +/-0.01 K and +/-0.001 MPa, respectively. In the experimental setup, an uncertainty in the mole fraction of u(x(j)) = +/-0.0015 has been achieved. Other properties related to P-rho-T-x data such as the compressibility factor, Z, excess molar volumes, V(m)(E), and partial molar volumes, V(i) and V(i)(infinity) have been calculated. The volumetric behavior has been compared with literature data and with that obtained from the PC-SAFT EoS rescaled parameters; these parameters have been obtained from our previous experimental values for the critical temperature and pressure of pure compounds. The value for the Krichevskii parameter, A(Kr), was obtained from the experimental density data for infinitely dilute solutions measured in this work, and it has been compared with that obtained from critical properties. Structural properties such as direct and total correlation function integrals and cluster size were calculated using the Krichevskii function concept.

Isothermal vapor–liquid equilibria of bromochloromethane or 1-bromo-2-chloroethane+tetrachloromethane or benzene. Experimental measurements and analysis in terms of group contributions

Abstract Isothermal vapor–liquid equilibria (VLE) have been measured for bromochloromethane+tetrachloromethane or benzene at 298.15 K and 313.15 K, and for 1-bromo-2-chloroethane+tetrachloromethane or benzene at 313.15 K. Bromochloromethane+tetrachloromethane shows azeotropic behaviour in the temperature range covered. These experimental results, along with our previous ones on excess enthalpies, are interpreted with two group contribution models: DISQUAC (DISpersive-QUAsiChemical) and modified (Dortmund) UNIFAC (UNIquac Functional group Activity Coefficients).

Excess volumes of (1-chlorobutane or 1,2-dichloroethane or tetrachloromethane or 1,1,2,2-tetrachloroethane + dichloromethane or trichloromethane) and of (dichloromethane + trichloromethane) at the temperature 298.15 K

The excess molar volumes VEm of {x(ClCH2CH2CH2CH3 or ClCH2CH2Cl or CCl4 or Cl2CHCHCl2) + (1 − x)(CH2Cl2 or CHCl3)} and of {(xCH2Cl2 + (1 − x)CHCl3} have been determined experimentally as a function of the mole fraction x from density measurements at the temperature 298.15 K. The excess molar volumes are negative except for mixtures containing tetrachloromethane and for (1-chlorobutane + dichloromethane). (Dichloromethane + trichloromethane) shows an almost “ideal” volumetric behaviour.

Discussion of the influence of CO and CH4 in CO2 transport, injection, and storage for CCS technology.

This paper discusses the influence of the noncondensable impurities CO and CH4 on Carbon Capture and Storage (CCS) technology. We calculated and drew conclusions about the impact of both impurities in the CO2 on selected transport, injection, and storage parameters (pipeline pressure drop, storage capacity, etc.), whose analysis is necessary for the safe construction and operation of CO2 pipelines and for the secure long-term geological storage of anthropogenic CO2. To calculate these parameters, it is necessary to acquire data on the volumetric properties and the vapor-liquid equilibrium of the fluid being subjected to CCS. In addition to literature data, we used new experimental data, which are presented here and were obtained for five mixtures of CO2+CO with compositions characteristic of the typical emissions of the E.U. and the U.S.A. Temperatures and pressures are based on relevant CO2 pipeline and geological storage site values. From our experimental results, Peng-Robinson, PC-SAFT, and GERG Equations of State for were validated CO2+CO under the conditions of CCS. We conclude that the concentration of both impurities strongly affects the studied parameters, with CO being the most influential and problematic. The overall result of these negative effects is an increase in the difficulties, risks, and overall costs of CCS.

Representation for binary mixtures of n-alcohols + sub and supercritical CO2 by a group-contribution method

Abstract In order to represent vapour–liquid equilibria of binary n -alcohol–carbon dioxide mixtures the excess function-equation of state method is used in which carbon dioxide is described by the IUPAC equation of state and alcohols by a Peng–Robinson type equation where the attractive parameter is estimated by a group-contribution method. The excess function is of the Van Laar type in which the interaction parameters are calculated by a group-contribution method. This approach allows to correlate and predict with quite good accuracy VLE of binary systems of alcohols and CO 2 , even for heavier alcohols.