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 (T_c) and critical pressure (p_c) of tert-butanol and alkane systems have not been studied. In this work, the experimental data of the T_c and p_c 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 T_c and p_c 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 T_c and p_c, respectively. The T_c and p_c 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 T_c and p_c were also used to verify and improve the accuracy of our previous prediction model.