GB466524A - Improvements in the manufacture and production of heavy oils poor in or free from asphalt - Google Patents

Abstract

Heavy oils free from asphalt are obtained by subjecting the products obtained from solid carbonaceous materials by extraction under pressure or mild destructive hydrogenation after removal of non fusible constituents, to an extraction treatment with light aliphatic hydrocarbons containing from four to seven carbon atoms in the molecule, separating from each other the oil and asphaltic layers thus formed, distilling off solvent from the oily layer and separating the latter by distillation into fractions of different boiling ranges, mixing the lower boiling fraction with the asphaltic layer and employing the mixture as pasting medium for a fresh charge of initial material. The extraction process is carried out by subjecting the solid material mixed with a middle oil and asphaltic products from a prior treatment to temperatures of 300 to 450 DEG C., preferably in stages of increasing pressure from 50 atmos. upwards while the mild destructive hydrogenation is carried out under similar conditions but with a high partial pressure of hydrogen. The usual catalysts may be used in both treatments. The products are freed from solids by filtration or centrifuging and are then extracted in a closed vessel at 20--200 DEG C., with butane, pentane, hexane, &c., or a benzine of similar boiling point. The extraction is preferably carried out at about the critical temperature of the extracting agent. A preliminary extraction with normally gaseous hydrocarbons may be made. The oils are separated from the precipitated asphalts and the solvent removed. The oil is then separated by distillation into a middle oil fraction boiling up to about 350 DEG C., which is mixed with the asphalt to serve as pasting agent for fresh material and a heavy oil from which a good lubricating oil can be obtained by treatment with hydrogen in presence of catalysts at 250--475 DEG C. under 100--300 atmos. pressure.