Characterization and Preparative Separation of HeavyCrude Oils, their Fractions and Tliermally Craclied Products by the Asphaltene Solubility Fractions Method

摘要

An improved method for the separation of asphaltene solubility fractions is presented that has been proven useful for the characterization of heavy crude oils and their fractions. Mixtures of heptane, dichloromethane and methanol are used to obtain four different and well defined asphaltene fractions with increasing solubility parameter. A good correlation (0.95) is found between the Solubility Fraction Method and the gravimetric asphaltenes for virgin materials. For processed samples, the correlation depends on the type of conversion process chosen (FCC cracked, thermal and hydroprocessing). Preparative separations and characterization of Mexican VR asphaltenes and a thermally cracked residue were carried out using the same set of solvents as the Solubility Fraction Method. The results indicated that the H/C ratio of the asphaltene fractions extracted decreased and the aromaticity increased with the solubility parameter of the solvent.