Measurement of the critical temperature and critical pressure of isopropanol and isobutanol blended with gasoline components

Abstract

Isopropanol and isobutanol are potentially partial substitutes for gasoline. The critical properties of isoalcohol-gasoline blends are of great importance to optimize their combustion and emission performance in engines. In this paper, the critical temperature (Tc) and critical pressure (pc) of eight miscible systems (isopropanol/isobutanol + n-hexane, isopropanol/isobutanol + n-heptane, isopropanol/isobutanol + n-octane, isopropanol/isobutanol + n-heptane + isooctane) were measured by the flow method in the range of 497.69–569.21 K and 2.495–4.766 MPa. Experimental results show that the addition of isopropanol and isobutanol can significantly reduce the Tc of C6-C8 alkanes by 0–60.85 K and increase the pc by 0–2.271 MPa. A model for calculating the Tc and pc of these mixtures is presented based on the Redlich–Kister equations. The maximum average absolute relative deviations of the Tc and pc are 0.08% and 0.46%, respectively.