CO2与2-丁醇二元系统的高压相平衡模型

采用固定体积可视观察法测定了在323.2~353.2 K温度范围内2-丁醇在CO₂中高压相平衡数据. 运用Peng-Robinson状态方程(PR)和van der Waals-2混合规则建立了相平衡模型, 并运用Chrastil半经验方程建立了溶解度方程. 通过优化计算得到了状态方程中的模型参数, 同时得到的Chrastil溶解度方程为c=ρ^3.3617·exp(-2198.8193/T+6.5545). 二元体系的溶解热为-18.2809 kJ/mol.     

Solubility of thiophene in carbon dioxide and carbon dioxide + 1-propanol mixtures at temperatures from 313 to 363 K

Solubility measurements of sulfur compounds in supercritical fluids are required in order to determine the feasibility of supercritical extraction for removing them from gasoline and diesel fuel. In this work, solubility of thiophene in CO₂ and in CO₂ + 1-propanol mixtures were measured from 313 to 363 K using an apparatus based on the static–analytical method. Vapor–liquid equilibria (VLE) data of binary mixtures were fitted to the Peng–Robinson equation of state (EoS) with classical mixing rules. The binary interaction parameters (k_ij) obtained were used to predict the VLE data of ternary systems. The calculated values given by this simple model agree well to the experimental data.     

Prediction of gas condensate properties by Esmaeilzadeh–Roshanfekr equation of state

The Esmaeilzadeh–Roshanfekr (ER) equation of state (EOS) is used to predict the PVT properties of gas condensate reservoir fluids. Three gas condensate fluid samples taken from three wells in a real field in Iran, referred here as SA1, SA4 and SA8, as well as five samples from literature have been used to check the validity of the ER EOS in calculating the PVT properties of gas condensate mixtures. Some experiments such as constant composition expansion (CCE), constant volume depletion (CVD) and dew point pressures are carried out on these samples. In order to have an unbiased comparison between the ER and the Peng–Robinson (PR) equation of state, van der Waals mixing rules are used without using any adjustable parameters (k_ij = 0). Also, no pure component parameters are adjusted. The critical properties and acentric factor for plus-fraction are estimated by the Kesler–Lee, Pedersen et al. and Riazi–Daubert characterization methods. The results of dew point pressure calculations show that the ER EOS has smaller error than the PR EOS. For some mixtures, relative volume, gas compressibility factor and condensate drop-out in CVD and CCE test were also predicted. Comparison results between experimental and calculated data indicate that the ER EOS has smaller error than the PR EOS. The total average absolute deviation was found to be 0.82% and 2.97% for calculating gas compressibility factor and gas specific gravity in CVD test. Also, the total average absolute deviation was found to be 2.06% and 3.42% for calculating gas compressibility factor and relative volume in CCE test.     

Solubility of iodopropynyl butylcarbamate in supercritical carbon dioxide

Supercritical carbon dioxide has been considered an appropriate alternative for extraction and purification process of cosmetics, pharmaceuticals, food supplements and natural products. Solubility information of biological compounds is essential for choosing supercritical fluid (SCF) processes. The solubility of iodopropynyl butylcarbamate (IPBC), a fungicide and anti-dandruff agent, was measured in supercritical carbon dioxide with a high pressure apparatus equipped with a variable volume view cell at 313.15, 323.15, and 333.15 K and at pressure between 80 and 35 MPa. The experimental data were correlated well with Peng–Robinson equation of state (PR EOS) and quasi-chemical nonrandom lattice fluid model.     

Description of the pVT behavior of ionic liquids and the solubility of gases in ionic liquids using an equation of state

A molecular thermodynamic model developed previously for fluids of chain-like molecules has been extended to correlate the pVT behavior of ionic liquids and the solubilities of gases such as CO₂, C₃H₆, C₃H₈, C₄H₁₀ in various ionic liquids. The relative deviation between the calculated molar volume and experimental data is less than 0.2%. It is shown that this equation of state can be used to correlate the solubility of CO₂ in ionic liquids with only one temperature-independent adjustable interaction parameter, and the accuracy of the correlation can be further improved using two temperature-independent adjustable parameters. The water content of ionic liquids has a large influence on the calculated results. For systems with water content lower than 0.1%, the average relative deviations of bubble point pressure are 3.14 and 4.90% using two parameters and one parameter, respectively. For systems containing C₃H₆, C₃H₈ and C₄H₁₀ two temperature dependent adjustable parameters are needed to obtain a good fit, and the corresponding deviation of the gas solubility is less than 2%, except for C₃H₈.     

Solubility calculation of pharmaceutical compounds – A priori parameter estimation using quantum-chemistry

Pure-component electrostatic properties for pharmaceutical compounds and intermediates (xanthene, ibuprofen, aspirin, p-hydroxyphenylacetic acid, p-toluic acid and o-anisic acid) were obtained by quantum-chemical methods. Afterwards, these properties were used for the a priori determination of the pure-component parameters for the Perturbed-Chain Polar Statistical-Associating Fluid Theory (PCP-SAFT). These parameters were applied to perform solubility calculations for binary solute–solvent mixtures. In these calculations the only parameter fitted was the binary parameter. The results show a good agreement of the modeled solubility and experimental data for the considered solutes in non-polar and polar solvents. Finally, the application of different combination rules to also predict the binary interaction parameter in the mixture was investigated.     

An equation-of-state-based viscosity model for non-ideal liquid mixtures

A viscosity model based on the Eyring’s theory and a cubic equation of state (Peng–Robinson–Stryjek–Vera) has been applied to the correlation and prediction of experimental liquid viscosities of binary mixtures containing polar fluids within a wide range of temperature, pressure and composition (encompassing low-pressure and compressed liquid conditions). Highly non-idealities of the binary mixtures considered in this study were conveniently handled via the application of the Wong–Sandler approach for the mixing rules used in the cubic equation of state. The results obtained were highly satisfactory for various non-ideal binary mixtures over the whole composition range at a low pressure. The predictive capabilities of the present approach were also verified in the representation of liquid viscosities at elevated pressures preserving the same model parameters previously obtained at low pressure.     

Excess molar volumes and viscosity deviations of the ternary system of 1-butanol + 2-butanol + 1,3-butanediol at 303.15 K

Abstract  The viscosity and density of ternary mixtures of 1-butanol + 2-butanol + 1,3-butanediol and the binary systems 1-butanol + 2-butanol, 1-butanol + 1,3-butanediol, and 2-butanol + 1,3-butanediol were measured at 303.15 K and atmospheric pressure over the entire range of compositions. Excess molar volumes V ^E and viscosity deviations Δη were obtained from the experimental results for the binary and ternary systems and fitted to Redlich–Kister’s and Cibulka’s equations in terms of mole fractions. The results obtained for the viscosity of liquid mixtures were used to test the semi-empirical relations of Grunberg–Nissan, Hind, and the two-parameter McAllister, Kendall, and Frenkel equations. The experimental data for the ternary system and the constituting binaries are analyzed to discuss the nature and strength of intermolecular interactions in these mixtures. Graphical abstract        

Solid-liquid equilibrium using the SAFT-VR equation of state: Solubility of naphthalene and acetic acid in binary mixtures and calculation of phase diagrams

A solid-liquid equilibrium (SLE) thermodynamic model based on the SAFT-VR equation of state (EOS) is presented. The model allows for the calculation of solid-liquid phase equilibria in binary mixtures at atmospheric pressure. The fluid (liquid) phase is treated with the SAFT-VR approach, where molecules are modelled as associating chains of tangentially bonded spherical segments interacting via square-well potentials of variable range. The equilibrium between the liquid and solid phase is treated following a standard thermodynamic method that requires the experimental temperature and enthalpy of fusion of the solute. The model is used to calculate the solubilities of naphthalene and acetic acid in common associating and non-associating organic solvents and to determine the solid-liquid phase behaviour of binary mixtures with simple eutectics. The SAFT-VR pure component model parameters are determined by comparison to experimental vapour pressure and saturated liquid density data with the choice of association models according to the nature of the molecule; in addition, an unlike adjustable parameter (k_ij) is used to model the solutions. The solubility data of naphthalene and acetic acid in both associating and non-associating solvents are reproduced essentially within the accuracy of the experimental measurements. The phase boundaries and the position of the eutectic points in the binary mixtures considered are, in most cases, reproduced with the accuracy commensurate with the industrial applications. Overall, the results presented show that the SAFT-VR EOS can be used with confidence for the prediction of the SLE of binary systems at atmospheric pressure.     

Viscosity of the systems m-xylene, +1-propanol, +2-propanol, +1-butanol, +t-butanol

Viscosities, η, of the systems, m-xylene, +1-propanol, +2-propanol, +1-butanol and +t-butanol have been measured for the whole range of composition at 303.15, 308.15, 313.15, 318.15 and 323.15?K. The variation of viscosities has been plotted against mole fraction of alkanols. Viscosities have been found to increase slowly up to a considerable concentration of alkanols, followed by a rapid rise of viscosities at higher concentrations. The slow rise of viscosity is attributed to dissociation of alkanols in m-xylene, while the rapid rise of viscosity is ascribed to self-association of alkanols. Excess viscosities, η^E, have been plotted as a function of mole fraction of alkanols. The curves show negative values for the whole range of composition, with minima occurring in alkanol-rich region.?η?and η^E have been fitted to appropriate polynomial equations. The study shows the effect of branching and chain length of alkanols on?η?and η^E.     

微扰理论状态方程预测高温高压电解质水溶液的密度

由于实验条件的限制,高温高压电解质水溶液密度的测定具有一定困难,现有文献中有关该类体系的实验数据很少．Lvov和Wood[1]采用Blum－Wei的电解质水溶液非原始模型的平均球近似（MeanSphericalApproximation,简称MSA）方程,对NaCl水溶液建立了状态方程,该方程中离子的硬球     

Experimental determination and prediction of methane hydrate stability in alcohols and electrolyte solutions

In petroleum exploration and production operations, gas hydrates pose serious flow assurance, economic and safety concerns. Thermodynamic inhibitors are widely used to reduce the risks associated with gas hydrate formation. In this communication, in order to establish the effects of salts and thermodynamic inhibitors on the locus of incipient hydrate–liquid water–vapour (H–L_W–V) curve, we report new experimental dissociation data for various quaternary systems, methane/water/thermodynamic inhibitor/salts for a pressure range of 6.89–29 MPa.     

CO在SnO2(110)面吸附特性的密度泛函研究

根据密度泛函理论, 采用广义密度近似和总体能量平面波赝势方法, 以6层Slab周期结构为模型, 计算了CO以4种不同方式在SnO2(110)表面的吸附, 研究了CO吸附对表面特性的影响. 计算结果表明, CO以C端向下在低配位Sn5C位置的顶位吸附为稳定的吸附方式, 该吸附对表面的驰豫现象有所改善. CO吸附并未明显改变表面电子态密度分布, 但造成了费米能1.06 eV的升高. 吸附后CO分子向表面转移了0.07个电子, 使表面电阻下降. 理论计算的结果支持了气体传感器气敏机理中的表面电导模型.     

Density improvement of the SRK equation of state

The SRK equation of state has been modified by volume translation in order to improve its accuracy both in- and outside the critical region. A temperature dependent volume correction is proposed which can match the true critical point of the pure component, and provides accurate densities for polar and non-polar pure substances both near to and far from the critical point. It can also be easily extended to mixtures, and the calculation results show that it can shift the critical locus towards experimental values and gives good results for the liquid densities of mixtures.     

A new cubic equation of state for simple fluids: pure and mixture

A two-parameter cubic equation of state is developed. Both parameters are taken temperature dependent. Methods are also suggested to calculate the attraction parameter and the co-volume parameter of this new equation of state. For calculating the thermodynamic properties of a pure compound, this equation of state requires the critical temperature, the critical pressure and the Pitzer’s acentric factor of the component. Using this equation of state, the vapor pressure of pure compounds, especially near the critical point, and the bubble point pressure of binary mixtures are calculated accurately. The saturated liquid density of pure compounds and binary mixtures are also calculated quite accurately. The average of absolute deviations of the predicted vapor pressure, vapor volume and saturated liquid density of pure compounds are 1.18, 1.77 and 2.42%, respectively. Comparisons with other cubic equations of state for predicting some thermodynamic properties including second virial coefficients and thermal properties are given. Moreover, the capability of this equation of state for predicting the molar heat capacity of gases at constant pressure and the sound velocity in gases are also illustrated.