LIQUID- SOLID AND LIQUID-VAPOR PHASE EQUILIBRIUM IN SECONDARY ALCOHOL - n-ALKANE SYSTEM

Abstract

Primary and secondary alcohols, obtained as a product of processing of plant raw materials, can be used as additives in fuel. Mixtures of n-alkanes, cyclic alkanes and aromatic hydrocarbons can act as a model for gasoline and diesel fuel. Therefore, it is necessary to study the characteristics of mixtures of alcohols with normal, cyclic and aromatic hydrocarbons. To simulate liquid-solid and liquid-vapor phase equilibria, a method is used to minimize excess Gibbs energy by the solvation parameter. The authors developed the PCEAS (Phase Charts Eutectic and Azeotropic Systems) software. The input data in the case of constant pressure are the temperature T 0 and the enthalpy of the phase change H 0 of the pure components. Prediction of the thermodynamic parameters of secondary alcohols is used to calculate the eutectic and azeotropic parameters of the secondary alcohol - n-alkane mixture: composition, temperature, melting enthalpy and evaporation. The model makes it possible to determine the average value of the association parameter in the liquid phase k . Experimental data for azeotropic mixtures made it possible to establish the association parameter in the vaporphase  of the systems under study. The results of calculations can be used to select the optimal composition and obtain the requiredcharacteristics of biofuel.