GB441104A - A process for separating non-lubricating hydrocarbon oils into their components - Google Patents

Abstract

Mineral oils of viscosity lower than lubricating-oils, such as gaoline, kerosene, or gas oil are separated into their components by extraction with two solvents led in counter current in which one solvent consists of saturated preferably aliphatic hydrocarbons containing 3 or more carbon atoms, having a boiling range outside that of the oil being treated, and the other a solvent for non-paraffinic components. Non-paraffinic solvents specified are liquid sulphur dioxide, furfurol, phenols, ketones, dichlordiethyl ether; aromatic or aliphatic nitriles or nitro-compounds such as nitrobenzene, nitromethane, nitronaphthalene, monochlor acetonitrile, naphthonitrile, benzonitrile; organic rhodanides, such as methyl rhodanide; amines such as aniline, naphthylamide; esters of mono- or polyvalent alcohols such as methyl or glycol formate; methyl or ethyl alcohol, aldehydes, such as thiophene aldehyde; nitroaniline or nitroanisole. Diluents such as benzol, toluene, naphthalene and ether may be added. Saturated hydrocarbon solvents specified are, propane, butane, pentane, hexane, nonane, hexadecane, gasoline, petroleum ether, paraffinum liquidum, refined spindle oil, paraffin wax, tetra- or decahydro naphthalene or naphthenes. The two solvents which are substantially immiscible may be introduced at opposite ends of an extraction column to which a temperature gradient is applied and the oil introduced at an intermediate point; or the oil may be mixed with one solvent and passed in counter flow 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 re-introduced 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, the anti-knock properties of natural, cracked or synthetic gasoline containing aromatic, unsaturated and naphthenic hydrocarbons is improved by extracting with gas oil and nitro benzene or liquid sulphur dioxide; the cetene number of gas oil (Diesel fuel) is improved by extraction with light hydrocarbons or lubricating oil and furfurol or acetonitrile. Kerosene for use as illuminating oil may also be treated. The process may be effected under increased, ordinary or reduced pressure. Distillates containing wax are preferably dewaxed before extraction. The oils may be finally treated with sulphuric acid or a bleaching earth.