(Liquid–liquid) equilibria for ternary and quaternary systems of representative compounds of gasoline+methanol at 293.15K: Experimental data and correlation

Identification of UNIQUAC binary interaction parameters in liquid-liquid equilibrium

“…Among the data used, those at 305.95 K were studied by Anderson and Prausnitz [15] to show the application of the UNIQUAC model to LLE. For the data at 293.15 K, García-Flores et al [45] proposed a set of interaction parameters for the original UNIQUAC model. The UNIQUAC model parameters for LLE of the studied ternary system were calculated adopting four different approaches:…”

“…However, nonlinear temperature-dependent UNIQUAC parameters were chosen to ensure no influence of the fitting error on the results and conclusions. The results given by the UNIQUAC model parameters calculated in this work were compared with the LLE representation obtained with the interaction parameters presented in García-Flores et al [45]. In García-Flores et al [45], the model parameters of Methanol + n-Heptane system were evaluated from the binary equilibrium data (a13 = 20.829 K and a31 = 607.14 K), while the remaining four parameters were estimated from ternary equilibrium data (a12 = -104.37 K, a21 = 1155.2 K, a23 = -233.82 K and a32 = 376.36 K).…”

“…This figure indicates that all five parameter sets ensure low mole fraction errors at this temperature. Calculated [45] Calculated (approach 1) Calculated (approach 2) Calculated (approach 3) Calculated (approach 4) Experimental However, a comparison between the parameters proposed in this study and in García-Flores et al [45] is needed. As pointed out by Marcilla et al [7], a reliable tool to judge the parameters is the plate point condition check for the ternary binodal curve [14,35].…”

Liquid balance - steam for methanol mixing - Benzen using the Peng Robinson and Van-Laar models

“…Therefore, it is of great importance to study systems composed of methanol and hydrocarbon components representative of gasoline. In 2013 García et al [9], focused on studying the diagrams of hydrocarbon phases such as gasoline and methanol through tertiary and quaternary systems, (heptane + benzene + methanol), (heptane + ethylbenzene + methanol), (heptane + m-xylene + methanol), (heptane + benzene + ethylbenzene + methanol), and (heptane + Benzene + m-xylene + methanol) at temperature of 293.15K and atmospheric pressure, to define the solubility of methanol in gasoline at low temperatures. The mixture of these components is not only used for fuel alcohol additives, it has also been used as a raw material for the synthesis of other chemicals and polymers; accurate data on the phase equilibrium of mixtures of propylene oxide with hydrocarbons (methanol-benzene) are necessary for proper design and optimization of the relevant chemical processes and purification steps [10].…”

Solution Structure of Isoactivity Equations for Liquid–Liquid Equilibrium Calculations Using the Nonrandom Two-Liquid Model

“…The minimum of the Gibbs free energy is a necessary and sufficient condition for stable phase equilibrium. However, the global minimum is often difficult to obtain for complex systems because of the mathematical difficulty caused by the highly nonlinear form of the objective function; additionally, incorrect phase distributions may arise if local minima are obtained. − , As a result, it is essential to have a stability test to verify whether a result corresponds to the global minimum, which is usually carried out by the tangent plane distance (TPD) criterion. − Consequently, minimizing the Gibbs free energy coupled with the stability test has become a popular procedure for calculating the phase equilibrium, and the procedure proceeds in a stepwise manner, with composition estimates generated by the stability test until a stable equilibrium state is found. − The stability test requires that F ( x ) (the distance between the Gibbs free energy surface and the tangent plane at composition z as a function of composition x ) be non-negative for all compositions x . While it is too time-consuming to exhaustively test all of the compositions, it is sufficient to test all of the stationary points of F ( x ).…”