GB475723A - Improvements relating to the refining of hydrocarbon oils - Google Patents

Abstract

Hydrocarbon oils are freed from asphalt, unsaturated or aromatic constituents by treatment with a liquefied normally gaseous fluorine compound. Dichlordifluormethane is excluded. The selective solvent property of aliphatic fluorinated compounds increases with the number of fluorine atoms present. The introduction of fluorine into hydrocarbons containing other halogens increase the selectivity property when the number of fluorine atoms equals or exceeds the atoms of other halogens. Selective solvents are, mono-, di-, or tri-fluormethane, carbon tetrafluoride, monoto hexafluorethane, monofluorethylene, monochlormonofluormethane, monobromtrifluorethane, or dichlortetrafluorethane. Non - selective solvents are dichlormonofluormethane and corresponding gaseous compounds of ethane propane, propylene, or ethylene. Asphalt is first removed at an elevated temperature in the presence of a non-selective solvent, and after chilling to remove wax if present, is then treated with a selective solvent to form raffinate and extract layers which are separated. The selective solvents may be admixed with other selective solvents such as phenol, furfurl or sulphur dioxide or with diluents such as non-selective fluorinated compounds, alcohol or, in some cases, water. The non-selective selective solvents may be used as diluents for a sulphuric acid treatment applied after separating asphalt and before de-waxing. Specifications 373,538 and 474,464, are referred to.