Browsing by Author "Canales, Roberto I."

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    Assessing Thermodynamics Models for Phase Equilibria and Interfacial Properties Relevant to the Hydrogenation of Carbon Dioxide
    (American Chemical Society, 2024) Cea-Klapp, Esteban; González-Barramuño, Bastián; Gajardo-Parra, Nicolás F.; Karelovic, Alejandro; Quinteros-Lama, Héctor; Canales, Roberto I.; Garrido, José Matías
    © 2024 American Chemical Society.The catalytic hydrogenation of carbon dioxide has become a novel technology of economic and environmental interest that allows the production of value-added products as energy alternatives to the current demand. As product distributions are highly dependent on process conditions such as reaction temperature, pressure, and H2/CO2 ratio, it is necessary to have reliable thermodynamic models that can characterize mixtures of reactants with products over a wide range of conditions. In this contribution, the accuracy of two hydrogen models applied through equations of state (EOS) framed within variations of the statistical associating fluid theory (SAFT) is compared. These models include perturbed-chain SAFT (PC-SAFT) EOS and SAFT of variable range and Mie potential (SAFT-VR Mie) EOS. This is accomplished by the depiction of the thermodynamic behavior of mixtures of hydrogen in the context of the hydrogenation of carbon dioxide, estimating the thermodynamic behavior of the relevant mixtures. In all of the cases, zero values for the binary adjustable parameters have been implemented, and both models of hydrogen were fitted from a hydrogen+decane mixture. Available experimental data of high-pressure phase equilibria, critical loci, and interfacial tensions is used to determine the accuracy of the hydrogen models by contrasting their respective predictive capabilities, determining that the overall performance of the one applied in the SAFT-VR Mie EOS is inferior compared to the PC-SAFT one. The average absolute deviations between model calculations and experimental data for vapor-liquid equilibrium are 35.8 % (pressure), 3.10 % (liquid composition), and 2.60 % (vapor composition) for PC-SAFT, and 26.3, 3.27, and 2.65% for SAFT-VR Mie, respectively.
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    Solubility of beta-carotene in ethanol- and triolein-modified CO2
    (ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD, 2011) Araus, Karina A.; Canales, Roberto I.; del Valle, Jose M.; de la Fuente, Juan C.
    Modification of an experimental device and methodology improved speed and reproducibility of measurement of solubility of beta-carotene in pure and modified SuperCritical (SC) CO2 at (313 to 333) K. Solubilities of beta-carotene in pure CO2 at (17 to 34) MPa ranged (0.17 to 1.06) mu mol/mol and agreed with values reported in literature. The solubility of beta-carotene in CO2 modified with (1.2 to 1.6) % mol ethanol increased by a factor of 1.7 to 3.0 as compared to its solubility in pure CO2 under equivalent conditions. The concentration of triolein in equilibrated ternary (CO2 + beta-carotene + triolein) mixtures having excess triolein reached values (0.01 to 0.39) mmol/mol corresponding to its solubility in pure SC CO2 under equivalent conditions. Under these conditions, the solubility of beta-carotene in triolein-modified CO2 increased by a factor of up to 4.0 in relation with its solubility in pure CO2 at comparable system temperature and pressure, reaching an uppermost value of 3.3 mu mol/mol at 333 K and 32 MPa. Unlike in the case of ethanol, where enhancements in solubility where relatively independent on system conditions, solubility enhancements using triolein as co-solvent increased markedly with system pressure, being larger than using (1.2 to 1.6)% mol ethanol at about (24 to 28) MPa, depending on system temperature. The increase in the solubility beta-carotene in SC CO2 as a result of using ethanol or triolein as co-solvent apparently does not depend on the increase in density associated with the dissolution of the co-solvent in CO2. Enhancements may be due to an increase in the polarizability of SC CO2, which possibly growths markedly as triolein dissolves in it when the system pressure becomes higher. (C) 2011 Elsevier Ltd. All rights reserved.