1-7　混合溶媒を用いたアスファルテン凝集制御

抄録

We tried to make a good mixed solvent for an asphaltene using poor solvents of hexane and benzyl benzoate, which are suggested by Hansen solubility parameter (HSP). The solubilities of asphaltene were measured in the mixed solvents at various mixing ratios. As a result, the solubility showed the maximum at the mixing ratio with δ_d, δ_p, and δ_h of 19.1, 4.2, and 4.3 MPa^0.5, respectively, which are almost the same as the HSPs of asphaltene. At the best mixing ratio, the small-angle X-ray scattering intensity at scattering parameters of >1 nm^–1 disappeared, meaning that the amounts of asphaltene nanoaggregates drastically decreased in the solvent system. All the results indicated that the HSP concept can propose the best mixing ratio of solvents even using poor solvents, which enabled us to control asphaltene aggregation behavior. It is surprising that the addition of poor solvent (hexane) enhances the asphaltene solubility and dispersibility. These interesting phenomena may give us important information to understand asphaltene molecules and their aggregation behavior.