Physical and rheological properties of deasphalted oil produced from solvent deasphalting

Because of the depletion of conventional oil and its increasing price, technologies that use unconventional oil and low-value crude residues are attracting great attention. Unconventional oil and low-value crude residues contain large amounts of asphaltene, which leads to high viscosity and includes a considerable amount of nitrogen, sulfur, and various metals. Therefore, to utilize such energy resources, asphaltene-removal processes (e.g., solvent deasphalting) are required to obtain deasphalted oil (DAO). DAO is generally used for lube base oils and is converted into transportation fuel and petrochemical raw materials by additional refinement. Herein, the physical and rheological properties of DAO were investigated to develop a better understanding of the DAO characteristics and its efficient utilization. The physical properties of DAO were analyzed by measuring elemental compositions; American Petroleum Institute gravity; saturates, aromatics, resins, and asphaltenes fractions; and boiling-point distributions, and the properties were compared with those of vacuum residues. The DAO viscosity was characterized using a rotational rheometer at various temperatures to analyze the effect of temperature on the DAO fluidity. The DAO viscosity greatly decreased with increasing temperatures and a distinctive transition was observed at ∼70 °C. In the shear viscosity and modulus analyses, DAO exhibited non-Newtonian behavior below 70 °C and Newtonian behavior above 70 °C.