Experimental determination of critical data of multi-component mixtures containing potential gasoline additives 2-butanol by a flow-type apparatus

• Critical properties of six binary systems and two ternary systems were measured.
• Six binary systems containing 2-butanol show non-ideal behavior in their Tc–x1 curves.
• Non-ideal behavior of mixtures with 2-butanol relies on azeotropy.
• Experimental data for binary systems were fitted well with Redlich–Kister equation.
• Critical surfaces of ternary systems were plotted using the Cibulka’s expressions.

In this work, we used a flow method for measurement of critical properties of six binary mixtures (2-butanol + cyclohexane, 2-butanol + hexane, 2-butanol + heptane, 2-butanol + octane, 2-butanol + nonane and 2-butanol + decane) and two ternary mixtures (2-butanol + hexane + heptane and 2-butanol + octane + decane). The critical properties were determined by observing the disappearance and reappearance of the gas–liquid phase meniscus in a quartz glass tube. The standard uncertainties of temperatures and pressures for both binary and ternary mixtures were estimated to be less than 0.2 K and 5.2 kPa, respectively. These critical data provide the boundaries of the two-phase regions of the related mixture systems. Six binary systems show non-ideal behaviors in the loci of critical temperatures. We used the Redlich–Kister equations to correlate the critical temperatures and pressures of these systems and listed the binary interaction parameters. The maximum average absolute deviation (AAD) of each binary system between experimental data and calculated results from Redlich–Kister equations is 0.038% for critical temperatures, and 0.244% for critical pressures. Moreover, the two ternary systems were newly reported and correlated by Cibulka’s and Singh’s expressions. The maximum AAD of critical temperatures and critical pressures are 0.103% and 0.433%, respectively.

Experimental critical pressures of 2-butanol + hexane + heptane system.Figure optionsDownload as PowerPoint slide