Measurement of critical temperature and critical pressure of tert-butanol and alkane mixtures

Tert-butanol is a good additive for improving gasoline performance, but as two of the most important thermodynamic properties, the critical temperature (Tc) and critical pressure (pc) of tert-butanol and alkane systems have not been studied. In this work, the experimental data of the Tc and pc of five binary systems (tert-butanol + cyclohexane, tert-butanol + n-hexane, tert-butanol + n-heptane, tert-butanol + n-octane, and tert-butanol + n-nonane) and a ternary system (tert-butanol + n-heptane + n-octane) were obtained using a flow method. The Tc and pc of the binary systems were fitted using the Redlich–Kister equations with maximum average absolute relative deviations (AARDs) of 0.19% and 0.36% for Tc and pc, respectively. The Tc and pc for tert-butanol + n-heptane + n-octane were correlated by Singh and Sharma's equations and Cibulka's equations with AARDs less than 0.09% and 0.32%, respectively. The experimental data of Tc and pc were also used to verify and improve the accuracy of our previous prediction model.