| Di-n-butyl phthalate and di-iso-butyl hexahydrophthalate are two important organicsolvents to recover maleic anhydride (MA) in the manufacture of MA. It is of greatsignificance to research the physical and chemical properties of them by experimentalmethods. The vapor pressures of the two solvents are determined by ebulliometermethod in this paper and three common equations are used to fit the data. The molarlatent heats of evaporation of the two solvents are calculated. The relationshipbetween the equilibrious pressures and equilibrious temperatures are determined whenMA solutions of various concentrations of the two solvents reach equilibrium by theebulliometer method. Based on the material balance, isothermal vapor-liquidequilibrium (VLE) data at 423.15 K,443.15 K and 463.15 K and isobaric VLE dataunder 3.33 kPa, 6.00 kPa and 8.67 kPa of MA with the two solvents are calculatedrespectively using NRTL model and the mean evaporation coefficient of theebulliometer. The NRTL model parameters of the two binary systems are correlated.Densities of the two solvents from the room temperature to 94℃ are determined bythe floating densimeter method and fitted with empirical equations. Viscosities of thetwo solvents from the room temperature to 80℃ are measured with the Ubbelohdeviscometer. R-D method is adopted to estimate the isobaric heat capacities of the twosolvents. According to the comparison of the properties of the two solvents, thefeasibility of the proposal to replace di-iso-butyl hexahydrophthalate with di-n-butylphthalate as MA recovery absorbant on the MA producing facilities is discussed.
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