Solid-liquid equilibria for dibenzofuran or Xanthene + Heavy Hydrocarbons: Experimental measurements and modelling

Abstract

The solid–liquid equilibria (SLE) phase diagrams have been determined using a DSC technique for dibenzofuran + n-C21, or + n-C31, or + n-C41 mixtures. The three systems show a eutectic point. Values of the eutectic temperature and of the heat of melting have been also evaluated and used to determine the eutectic composition of the systems by means of the Tamman’s plots. The dependence of deviations from ideality of dibenzofuran + aromatic hydrocarbon mixtures with size, shape, and of the degree of alkylation of the hydrocarbon has been investigated. At this end, we have considered SLE data available in the literature for solutions including benzene, acenaphthene, phenanthrene, anthracene, biphenyl, chrysene, toluene, or diphenylmethane. Dibenzofuran + n-alkanes systems show positive deviations from the ideal solution model, which increase with the alkane size. The mentioned deviations are stronger in the corresponding xanthene solutions. DISQUAC interaction parameters have been obtained for the (aromatic/ether) and (aliphatic/ether) contacts in dibenzofuran or xanthene + aromatic hydrocarbon, or + n-alkane mixtures. Better fitting is obtained with DISQUAC model compared to the Ideal Solubility Model, or UNIFAC model. Finally, the COSMO-RS model was used to predict the eutectic coordinates for the binary systems Dibenzofuran + n-alkanes (n-C21, or n-C31 or n-C41). Excellent agreement was obtained only for the eutectic temperature.