Thermodynamic Properties Of Co Research Articles

Study of Structural, Electronic, Magnetic, Elastic, and Thermodynamic Properties of Co4N Antiperovskite by First Principles and Monte Carlo Simulation

The antiperovskite Co4N is studied using density functional theory (DFT) calculations and Monte Carlo (MC) simulation within the framework of the Ising model. The structural, density of states (DOS), and band structure calculations show that Co4N is a ferromagnetic material having a higher magnetic moment, a large spin polarization ratio, and exhibits a metallic behavior. The investigated elastic constants, phonon dispersion, and phonon DOS show that the Co4N compound is mechanically and dynamically stable. It is also found that the Co4N is ductile from the Poisson's ratio, Pugh's ratio, and Cauchy pressure. The thermodynamic parameters like heat capacity, Debye and melting temperature are calculated. The magnetization, magnetic susceptibility, and the Curie temperature of magnetic transition are estimated using MC simulations based on the Ising model. The obtained value of TC is in good agreement with available theoretical work.

Prediction of Thermodynamic Properties of CO2 by Cubic and Multiparameter Equations of State for Fluid Dynamics Applications

This paper makes a comprehensive analysis of equations of state (EOS) for the prediction of thermodynamic properties of CO2 which play a key role in fluid dynamics calculations: molar volume, throt...

Absorption and thermodynamic properties of CO2 by amido-containing anion-functionalized ionic liquids.

In this contribution, two kinds of amido-containing anion-functionalized ionic liquids (ILs) were designed and synthesized, where the anions of these ILs were selected from deprotonated succinimide (H-Suc) and o-phthalimide (Ph-Suc). Then, these functionalized ILs were used to capture CO2. Towards to this end, solubility of CO2 in the ILs was determined at different temperatures and different CO2 partial pressures. Based on these data, chemical equilibrium constants of CO2 with the ILs were derived at different temperatures from the “deactivated IL” model. The other thermodynamic properties such as reaction Gibbs energy, reaction enthalpy, and reaction entropy in the absorption were also calculated from the corresponding equilibrium constant data at different temperatures. It was shown that these anion-functionalized ILs exhibited high CO2 solubility (up to 0.95 mol CO2 mol−1 IL) and low energy desorption, and enthalpy change was the main driving force for CO2 capture by using such ILs as absorbents. In addition, the interactions of CO2 with the ILs were also investigated by 1H NMR, 13C NMR, and FT-IR spectroscopy.

Solubilities and Thermodynamic Properties of CO2 in Four Azole-Based Deep Eutectic Solvents

The solubility data of CO2 in four azole-based deep eutectic solvents (DESs), prepared from azoles (imidazole, Im; 1,2,4-triazole,Tri) and acetylcholine chloride (ACC), were reported at temperatures of 303.15, 313.15, 323.15, and 333.15 K under a pressure range of (20.0- 600.0) kPa using the isochoric saturation method. Henry’s constants and thermodynamic properties of standard Gibbs free energy, enthalpy, and entropy changes of CO2 dissolution were derived by correlating the data. Results demonstrated that ACC-Im DESs (Hm = 1.91–4.46 MPa·kg·mol–1) possess higher capacities of CO2 than CC-Tri ones (Hm = 2.66- 4.58 MPa·kg·mol–1). The CO2 solubility increased with rising pressure, mole ratio of Im to ACC, and decreasing temperature. All the obtained enthalpies of solution were negative. Furthermore, the comparison of dissolution capacities between present DESs and other DESs as well as some ionic liquids in the literature was conducted.

Thermodynamic Properties of Co–Pr Alloys

The mixing enthalpies of the Co–Pr liquid binary alloys are determined by isoperibol calorimetry in the composition ranges 0 < x Pr < 0.23 and 0.4 < x Pr < 1 at 1500–1820 K. The thermodynamic properties of the Co–Pr liquid binary alloys are calculated for the entire composition range using the model of ideal associated solutions. The thermodynamic activities of components show negative deviations from the ideal behavior; the mixing enthalpies are characterized by moderate exothermic effects. The minimum mixing enthalpy of melts is –12.0 kJ/mol at x Pr = 0.46.

First-principles study on structural, electronic, elastic and thermodynamic properties of the full-Heusler alloys Co2YZ (Y=Sc, Cr and Z=Al, Ga)

First-principles calculations based on density functional theory (DFT) and quasi-harmonic Debye model are performed to study the structural, elastic, electronic and thermodynamic properties of the Co 2 YZ (Y=Sc, Cr and Z=Al, Ga) Heusler alloys. It is found that the spin polarization of Co 2 CrZ at Fermi level raises considerably, and Co 2 ScZ keeps the non-magnetic feature when the external pressure increases. Although outstanding performance of half-metallicity appears to Co 2 CrZ, the dynamical stability order exhibits that Co 2 ScZ > Co 2 CrZ as the result of phonon dispersion analysis. The influence of external pressure and temperature on the volume compression ratio, bulk modulus, heat capacity and thermal expansion coefficient are took fully into account and the outcomes from calculation obey the corresponding thermomechanics laws in the quasi-harmonic Debye model.

Heat capacities and thermodynamic properties of Co(3,5-PDC)(H2O)

A novel metal-organic frameworks Co(3,5-PDC)(H2O) (CoMOF, 3,5-PDC = pyridine-3,5-dicarboxylic acid) has been synthesized hydrothermally and characterized by single-crystal XRD and FT-IR spectra. The thermal stability and the decomposition mechanism of CoMOF were investigated by thermogravimetry-mass spectrometry, and a two-stage shape curve of mass loss was observed. Moreover, the low-temperature molar heat capacities were measured by temperature-modulated differential scanning calorimetry for the first time. The thermodynamic parameters such as entropy and enthalpy relative to reference temperature 298.15 K were derived based on the molar heat capacity data.

Thermodynamic modeling for CO 2 absorption in aqueous MEA solution with electrolyte NRTL model

Accurate modeling of thermodynamic properties of CO 2 absorption in aqueous alkanolamine solutions is essential for simulation and design of such CO 2 capture processes. In this study, we use the Electrolyte Nonrandom Two-liquid activity coefficient model in Aspen Plus to develop a rigorous and thermodynamically consistent representation for the MEA–H 2O–CO 2 system. Vapor–liquid equilibrium (VLE), heat capacity and excess enthalpy data for the binary aqueous amine system (MEA–H 2O) are used to determine the NRTL interaction parameters for the MEA–H 2O binary. VLE, enthalpy of absorption, heat capacity and NMR spectroscopic data for the MEA–H 2O–CO 2 ternary system are used to identify the electrolyte NRTL interaction parameters for the molecule–electrolyte binaries and the previously unavailable standard state properties of the amine ions, MEA protonate and carbamate. The predicted VLE, enthalpy of absorption, heat capacity and speciation for the MEA–H 2O–CO 2 system are compared favorably to experimental data.

CO 2 capture properties of alkaline earth metal oxides and hydroxides: A combined density functional theory and lattice phonon dynamics study

By combining density functional theory and lattice phonon dynamics, the thermodynamic properties of CO(2) absorption/desorption reactions with alkaline earth metal oxides MO and hydroxides M(OH)(2) (where M=Be,Mg,Ca,Sr,Ba) are analyzed. The heats of reaction and the chemical potential changes of these solids upon CO(2) capture reactions have been calculated and used to evaluate the energy costs. Relative to CaO, a widely used system in practical applications, MgO and Mg(OH)(2) systems were found to be better candidates for CO(2) sorbent applications due to their lower operating temperatures (600-700 K). In the presence of H(2)O, MgCO(3) can be regenerated into Mg(OH)(2) at low temperatures or into MgO at high temperatures. This transition temperature depends not only on the CO(2) pressure but also on the H(2)O pressure. Based on our calculated results and by comparing with available experimental data, we propose a general computational search methodology which can be used as a general scheme for screening a large number of solids for use as CO(2) sorbents.

Thermodynamic properties of CO 2 absorption in hydroxyl ammonium ionic liquids at pressures of (100–1600) kPa

Solubility of CO 2 in six hydroxyl ammonium ionic liquids 2-hydroxyethanaminium acetate [hea], bis(2-hydroxyethyl)ammonium acetate [bheaa], 2-hydroxy- N-(2-hydroxyethyl)- N-methylethanaminium acetate [hhemea], 2-hydroxyethanaminium lactate [hel], bis(2-hydroxyethyl)ammonium lactate [bheal], 2-hydroxy- N-(2-hydroxyethyl)- N-methylethanaminium lactate [hhemel] at temperatures (298.15, 313.15, and 328.16) K and pressures ranging from (100 to 1600) kPa was determined. From the experimental solubility data, the Henry’s constant of CO 2 for each hydroxyl ammonium ionic liquids was estimated and reported as a function of temperature. Furthermore, enthalpy and entropy of absorption were obtained from estimated Henry’s constant. The results showed that the solubility increase with increasing pressure and decrease with increasing temperature and the solubility of CO 2 in these six hydroxyl ammonium ionic liquids was in sequence: [hea] > [bheaa] > [hel] > [bheal] > [hhemel] > [hhemea].

Study on two-phase flow pattern of supercritical carbon dioxide with entrained PAG-type lubricating oil in a gas cooler

In order to clarify the heat transfer mechanism of supercritical carbon dioxide flowing with a small amount of lubricating oil, visualization experiments were conducted using two sight glass tubes with inner diameters of 2 and 6 mm. The visualization images were recorded using a high-speed CCD camera with shutter speed changing from 500 to 10,000 pps (pictures per second). PAG-type oil, which is partially miscible with supercritical carbon dioxide, was used. The experiments were conducted with lubricating oil concentrations of 1 and 5 wt%, pressures between 8 and 10 MPa, and mass fluxes between 200 and 1200 kg m −2 s −1. The visualization images revealed that the two-phase flow pattern inside the gas cooler was determined by many factors, including the tube diameter, oil concentration, temperature, pressure, and mass flux. For a small size tube of 2 mm ID, the formation of both oil droplets in the bulk region and an oil film along the inner wall of the tube was confirmed. At low temperatures, a large number of oil droplets were observed flowing with CO 2 with a slip ratio of approximately 0.7. With an increase in the bulk temperature, both the dimension and number of oil droplets entrained with CO 2 decreased, and the flow of the oil film became clearly visible. For a large tube of 6 mm ID, the flow pattern at a low mass flow rate was a separated wavy flow; with an increase in mass flow, the flow pattern changed to annular flow, which corresponds to a distinct decrease in the heat transfer coefficient due to the heat resistance of oil layer. The transition of the flow pattern is considered due to the shear stress between the oil layer and bulk CO 2. In addition, the dissolution of CO 2 into PAG oil as well as the change in the solubility and thermodynamic properties of CO 2 with the temperature and pressure makes the prediction of the flow patterns a challenging task. The relationship between the flow pattern and heat transfer characteristics was also discussed.

Experimental determination and calculation of thermodynamic properties of CO 2 + octane to high temperatures and high pressures

The phase behavior and critical points of carbon dioxide + octane are determined from 313 to 393 K, and their molar volumes and densities are measured both in the subcritical and supercritical (SC) regions using a variable-volume autoclave in this study. The critical curve of carbon dioxide + octane has been predicted with an equation of state (EOS) by Heilig and Franck, in which a repulsion term and a square-well potential attraction term for intermolecular interaction has been used. To use the pairwise combination rule for the square-well molecular interaction potential, three adjustable parameters are required. The thermodynamic properties including mole fractions, densities and molar volumes of this system are also calculated using the Heilig–Franck, the Peng–Robison (PR) and the Peng–Robinson–Stryjek–Vera (PRSV) equation of state. Among the equations of state, the Heilig–Franck equation of state has been found to have the best correlation with binary vapor–liquid equilibrium data of the carbon dioxide + octane system.

Study on the phase behaviors, viscosities, and thermodynamic properties of CO2/[C(4)mim][PF(6)]/methanol system at elevated pressures.

An apparatus to determine the vapor-liquid equilibria of CO(2)/ionic liquid (IL)/organic solvent multisystems and the viscosity of the liquid phase at elevated pressures has been constructed. The solubility of CO(2) in 3-butyl-1-methyl-imidazolium hexafluorophosphate ([C(4)mim][PF(6)]) and the viscosity of CO(2)-saturated [C(4)mim][PF(6)] have been studied at 313.15, 323.15, and 333.15 K and at pressures up to 12.5 MPa. The phase behavior of CO(2)/[C(4)mim][PF(6)]/methanol ternary mixture and the viscosity of the liquid phases at equilibrium condition have also been determined at 313.15 K and at 7.15 and 10.00 MPa. The partition coefficients of the components in the ternary system are calculated. Peng-Robinson equation of state and some thermodynamic functions are combined to calculate the fugacity coefficients of the components in the system. It demonstrates that the viscosity of the IL-rich phase decreases significantly with increasing pressure of CO(2), and the effect of temperature on the viscosity of CO(2)/IL mixture is not noticeable at high pressure, although the viscosity of the CO(2)-free IL decreases dramatically with increasing temperature. Compressed CO(2) may become an attractive reagent for reducing the viscosity of ILs in many applications. The mole fraction of methanol in the CO(2)-rich phase is much lower than that in the IL-rich phase; this indicates that the interaction between the IL and methanol is stronger than that between CO(2) and methanol. The fugacity coefficient of CO(2) in IL-rich phase is larger than unity, while that of methanol is much small than unity, which further suggests that methanol-IL interaction is much stronger than CO(2)-IL interaction. However, the CO(2)-IL interaction is stronger than the CO(2)-methanol interaction.

Thermodynamic properties of Cobalt–Praseodymium alloys

The thermodynamic properties of Co–Pr alloys have been determined between 973 and 1073 K by electromotive force measurements on galvanic cells employing CaF 2 as a solid electrolyte. Results yield a complete set of thermodynamic functions for the intermetallic phases (Co), Co 17Pr 2, Co 5Pr, Co 7Pr 2, Co 3Pr, and Co 2Pr which are compared with data for analogous alloys available from the literature and with predicted values from the Miedema model. The influence of the electronic structure of the components on the energetics of alloy formation is discussed.

Critical evaluation of thermodynamics of complex formation of metal ions in aqueous solutions. V. hydrolysis and hydroxo-complexes of Co 2+ at 298.15 K

The standard thermodynamic properties of Co 2+, its hydrolysis reactions and hydroxo-complex formation were evaluated on the basis of published experimental studies and the Specific interaction theory (SIT) for activity coefficients modeling. A set of thermodynamic data and interaction coefficients were obtained.

Thermodynamic properties of Co(OH)2 from hydrothermal equilibria in cobalt oxide systems

The preparative aspects of cobaltous and cobalitic oxides have been the subject of extensive investigations by various workers [1-6] because of their numerous applications in the field of ceramic, magnetic materials, catalysis and even in the extraction of cobalt metal. However, all these studies were confined to either 1 atm pressure or under vacuum conditions. Because hydro- thermal method has not so far been explored for the stabilization of CoO, a systematic study of the systems CoO HzO and CO304-H20 were taken up. Taking advantage of the experimental data, it was possible to determine the standard thermodynamic properties of Co(OH)z. The starting material, Co(OH)z , was precipitated by hydrolysis of cobalt nitrate solution with aqueous ammonia at room temperature. The precipitate during filtration was washed well with hot water in order to remove the possible nitrate ion contamination. The precipitate was dried in an air oven at 90°C and was confirmed to be Co(OH)2 by X-ray diffraction. Co304 was obtained by decomposing Co(OH)z in air at 350 ° C. Hydrothermal runs were carried out using the tempress unit HR-1B-4 fitted with stellite test-tube reactors. The starting material, Co(OH)2 or C0304, was placed in a platinum ampoule (5cm × 5mm diameter, 0.1 mm wall thickness) along with a few drops of distilled water and the ampoule was sealed. The ampoule was checked for leaks by extended heating at 100 ° C. The duration of runs ranged between 48 and 60h. The upper pressure and temperature limits used in the present study were 2000 bar and 800 ° C, respectively. The phase diagrams for the system CoO- HzO and Co304-HzO are given in Figs 1 and 2 and the cor- responding data of experimental points are given in Table I. In the system CoO-HzO, the cobalt hydroxide decomposes to cobaltous oxide at considerably lower temperature (i.e. at 2000 bar it decomposes at 230 ° C), whereas in the Co3 O4-HzO system the decomposition to cobaltous oxide takes place at relatively high temperature (at 200bar it decomposes at 675 °C). However, it may be noted that the hydrothermal stabilization of CoO was possible at much lower tem- peratures than those reported from the decomposition studies in air. It is well known that the decomposition of Co(OH)2 to CoO in air proceeds through an inter- mediate phase of Co304. Furthermore, the decompo- sition of Co3 04 to CoO in air was found to be above 800°C and that under vacuum was at 350 ° C. The decomposition of Co(OH)2 directly to CoO was, how- ever, possible under vacuum conditions even at 140 ° C [5]. We first thought that the low temperature for the hydrothermal stabilization of CoO was due to hydro- gen diffusion through the platinum ampoule, as was previously reported for hydrothermal synthesis of Fe304 [7, 8]. The hydrogen liberated from the reaction of HzO with the metal of the reactor penetrates through the platinum tube. But this possibility was eliminated by conducting two experiments in Co(OH)z-HzO systems using quartz tube (375 ° C and 1000 bar) as well as a teflon-lined low-pressure bomb (250°C and 100bar) wherein the product was CoO and not

Thermochemistry of Cobalt Sulfate and Hydrates of Cobalt and Nickel Sulfates. Thermodynamic Properties of Co2+(aq) and the Cobalt Oxidation Potential

Thermochemistry of Cobalt Sulfate and Hydrates of Cobalt and Nickel Sulfates. Thermodynamic Properties of Co²⁺(aq) and the Cobalt Oxidation Potential

Thermodynamic properties of CO 2 up to 3000 atmospheres between 25 and 150°C

In previous papers (Michels and Michels 1935; Michels, Michels and Wouters 1935) the results of isotherm measurements on CO 2 and a method for interpolation of the pv values at intermediate temperatures and densities have been published. From the data obtained, the specific heat at constant volume C v , the free energy F , the total energy U , and the entropy S , have been calculated, and these results are given in the present communication. The values of F, U and S at N. T. P. have been taken as zero. The values of C v , F, S and U at a density of 1 Amagat unit ( ρ = 1) have first been calculated for different temperatures. To the values, so obtained, has been added the increase of these quantities by compression. The values of C v at ρ = 1 have been calculated, using the interpolation formula as given by Shilling and Partington (1928).