GB441136A - A process for separating hydrocarbon oils into their components - Google Patents

Abstract

Hydrocarbon oils containing lubricating-oils are separated into their components by treating with two solvents led in countercurrent and consisting of a solvent for non-paraffinic components and a saturated preferably aliphatic hydrocarbon solvent of paraffin components and containing at least 11 carbon atoms and having a boiling range lying outside that of the oil being treated. Non-paraffinic solvents specified are liquid sulphur dioxide, furfurol, phenols, cresols, ketones, dichlor diethyl ether; aromatic or aliphatic nitriles or nitro-compounds such as nitrobenzene, nitronaphthalene or nitromethane, monochloracetonitrile, naphthonitrile, benzonitrile; organic rhodanides such as methyl rhodanide; amines such as aniline, naphthylamine; esters of mono- or polyvalent alcohols such as methyl or glycol formate; methyl or ethyl alcohol; thiophene aldehyde, nitroaniline or nitroanisole. Saturated hydrocarbon solvents specified are kerosene, hexadecane, refined spindle oil, paraffin wax, paraffinum liquidum, homologues of deca or tetrahydronaphthalene, and naphthenes. Diluents such as benzol, toluene, naphthalene or ether may be added. The two solvents which are substantially mutually immiscible may be introduced at opposite ends of an extraction column to which a temperature gradient is applied over the whole or a part of the column and the oil introduced at an intermediate point; or the oil may be mixed with one solvent and passed in counterflow with the second solvent; or the oil flowing in counter current with one solvent is treated over a part of the path with the second solvent, the resulting extract is drawn off, freed from solvent and the residue reintroduced into the system. The extraction may also be effected in a series of mixers and settlers. The two solvents used should have appreciably different molecular weights whereby the critical solution temperature is substantially higher than the extraction temperature; for example, kerosene with nitrobenzene or liquid sulphur dioxide; refined spindle oil with acetonitrile; gas oil with maleic or succinic nitrile. Cracked oils or distillates are preferably dewaxed before extraction. The purified lubricating oils may be finally treated with sulphuric acid or a bleaching earth. The process may also be applied to regenerate waste hydrocarbon lubricating oils. Specification 355,294 is referred to. The Specification as open to inspection under Sect. 91 comprises also the treatment of hydrocarbons other than lubricating oils and using as saturated hydrocarbon solvent, hydrocarbons having at least 3 carbon atoms. This subject-matter does not appear in the Specification as accepted, but appears in Specifications 441,104 and 441,105.