GB462630A - A process of refining hydrocarbon oils - Google Patents

Abstract

Hydrocarbon fractions containing sulphur are rectified together with a selective solvent in a distillation zone, hydrocarbon fraction and solvent being continuously introduced, and a top product containing solvent and refined hydrocarbons and a bottom product containing the bulk of the sulphur compounds with or without solvent and hydrocarbons being continuously withdrawn. The hydrocarbon fractions may be gasoline, kerosene, naphthas, solar oils, and fuel oils, which may be either straight-run or cracked distillates, and may be derived from petroleum crudes, fractions of coal tar or brown coal tar, and mixtures obtained by the hydrogenation of carbonaceous substances. The solvent used must form one phase with the hydrocarbon fraction at the boiling temperature and have a boiling point low enough to cause a mixture of the said solvent and the highest boiling hydrocarbon in the fraction to boil at a lower temperature than the lowest boiling sulphur compound to be removed. The solvent may have a boiling point not substantially above the lower limit of the boiling range of the hydrocarbon fraction under treatment. There may be used as solvents organic compounds, either aliphatic, carbocyclic, or heterocyclic, containing one or more nitro, nitrile, thiocyanic, carboxyl, primary secondary or tertiary alcoholic, monochlor, amino, thiocarbonyl, carboxyl, or alkyl or aryl ether or ester groups. Examples are nitrobenzene, benzonitrile, monochloracetonitrile, phenyl-thiocyanate, phenolthiocyanate, formate of pyridine, benzaldehyde, acetone, furfuryl alcohol, chlorisopropyl alcohol, diacetone alcohol, methyl lactate, triacetin, di-acetin, methyl nitrobenzoate, formic acid, ethylene chlorhydrin, glycol monoacetate, glycol diacetate, lactic nitrile, toluidine, chlorpyridine, b b <1>-dichlordiethyl ether, chloraniline, quinoline, isoquinoline, pyridine, chlorphenol, sulphur dioxide, or preferably furfural, aniline methyl cyanide, ethylene diamine, nitromethane, or acetic anhydride, including isomers. It is preferable to fractionate in such a manner that the ratio of total hydrocarbons to the solvent in the rectified mixture withdrawn as a top product is maintained equal to the ratio thereof in the feed. This may be effected according to either of the following modes of operation: (a) the overhead mixture, or a portion thereof, is treated to withdraw therefrom a top product containing the solvent and the hydrocarbons in the same ratio as they occur in the feed, and the remaining portion of the overhead mixture is returned to the column; the top product may be withdrawn by chilling the portion of the overhead which is to be treated so as to cause it to separate into two liquid phases, or by adding water or another substance, e.g. methyl alcohol, to the overhead mixture or to the condensate, separating these phases, and withdrawing therefrom such quantities as are required to produce a top product of the desired composition; (b) the ratio of the solvent and the initial sulphur-bearing hydrocarbon fraction is so controlled as to produce a feed composition which contains the solvent and the hydrocarbons in the same ratio as they occur in the overhead mixture, which is then withdrawn as a top product. If it be impossible to keep the said ratios equal, it is preferable that the ratio of hydrocarbon to solvent be greater in the top product than in the feed. The initial hydrocarbon fraction may be first fractionated, preferably into fractions having a boiling point range of not more than 80 DEG C., and one or more of the fractions separately treated by the above process with or without the feature of adjusting the feed and top product compositions, e.g. those fractions difficult to de-sulphurize by ordinary methods may be so treated. The process is illustrated by a flow diagram (not shown). Specifications 324,350, [Class 2 (iii)], and 365,571 are referred to. The Specification as open to inspection under Sect. 91 refers also to batch processes. This subject-matter does not appear in the Specification as accepted.