Critical and maximum temperatures of coexistence of liquid and gas phase in hydrocarbons binary mixtures. I. Critical (vapour–liquid) temperatures of alkane binary mixtures

The physicochemical data on the mixtures with larger differences between the critical temperatures of their compounds is essential for the development of supercritical technologies-based industrial processes. As the experimental data on such mixtures are limited it is necessary to have the thoroughly tested methods to estimate their critical properties. Mixtures of alkanes play the key role in development and testing of such methods.The following work systematizes the data on critical temperatures for 56 binary mixtures which have C1–C6 alkanes as the first component and C2–C16 as the second. The possibilities and limitations for some combination methods to predict the critical temperatures of alkanes are defined. We evaluated the possibilities and the limitation of Kay's and Higashi's equations and the additive calculation based on the mass fractions of the component for the prediction of critical temperatures of alkane binary mixtures. The results of our experiments have shown that the best predictions were obtained using Higashi's equation, with the coefficient calculated on the basis of the difference in the critical temperatures of the components. For the mixtures with the difference in critical temperatures not exceeding 200 K, the additive calculation based on the mass fractions of the components presents a suitable alternative.