Solvent Fractionation is a method of separating petroleum its separate groups of defined liquid, to reach a product of interest, parameters, and need. In a distillation process the incoming feed stock is separated it into different components with respect to defined parameters such as boiling point. ¹ When solvent fractionation is used through deasphalting, the feed is separated into different fractions based on the solubility behavior of the material.¹ This process is often used to separate out vacuum distillation residue or VDR which are present in the feed. This allows for the recovery of asphalt and deasphalted oil from the feed, which then can be catalytically cracked and treated to obtain valuable petroleum products.² This process allows for an improved petroleum treating process, better method for recovery of lubricating oil stocks from petroleum residua, provides a method for the recovery of lubricating oil stocks from a petroleum residuum, and provide a method for improved yield of lubricating oil.² The process behind this technique is solvent extraction. The first step of this process is to have the VDR fed to the deasphalter. The feedstock is then contacted with a solvent in a countercurrent extractor at temperatures and pressures to precipice the asphalt and resin fractions that are not soluble in the solvent.³ This then lead to the final product, with a separated out feed of asphalt. In this process an important concept is the solvent power. This is the ability of the solvent to dissolve asphaltenes.⁴ With non-polar solvents the solvent power can be expressed by the parameter δ which is defined as the ratio between the surface tension and the cubic root of the molar volume.⁴ This parameter allows for the explanation of certain apparent anomalies, such as the insolubility of asphaltenes and complete solubility. ⁵ It also produces an agreement with the derivation of the solubility parameter, for any one series of solvents the relationship between the amount of precipices and the solubility parameter.⁵

1. Course web page
2. http://www.google.com/patents/US3074882
3. http://www.intertek.com/testing/pilot-plants/deasphalting/
4. The Chemistry and Technology of Petroleum  By James G. Speight
5. Petroleum Refining Processes edited by James G. Speight, Baki Ozum