GB444535A - A process for refining hydrocarbon mixtures - Google Patents

Abstract

Hydrocarbon oils such as lubricating oil distillates are separated into their components by extraction with a selective solvent for non-paraffinic components in the presence of a polycyclic aromatic hydrocarbon. Mixtures of naphthalene with furfurol are excluded. Aromatic hydrocarbons specified are, naphthalene, poly-alkyl naphthalenes; diphenyl, ditolyl, diphenyl alkanes, such as diphenyl-methane or ethane, stilbene or tolane, or partially hydrogenated products of these; anthracene, or homologues thereof; phenanthrene, retene, triphenylmethane, triphenyl benzene, or indene. Mixtures of these substances may be used, alone or diluted with light naphtha, benzene or toluene. Concentrated extracts of bicyclic hydrocarbons obtained from mineral oil may also be used, especially from naphthenic mineral oil fractions boiling between 180 and 300 DEG C. Selective solvents specified are, sulphur dioxide, furfural, dichlorethyl ether, acetone, nitromethane, nitrobenzene, dimethyl sulphate or sulphite, methyl formate, phenols, nitriles such as aceto-nitrile or benzonitrile, amines, pyridine, quinoline, isoquinoline, quinaldine, picoline, butidine, thiophene aldehyde, alcohols, glycol, esters or nitrogen bases from petroleum. The extraction may be effected in a batch process or by flowing the oil and solvents in countercurrent. A part of the extract may be drawn off, freed from solvent and returned to the extraction zone. The oil may be pre-extracted with the selective solvent alone to remove a part of the naphthenic constituents before the main extraction. The raffinate and extract are finally freed from solvent by centrifuging or distillation.