GB466977A - Process for refining hydrocarbon oils - Google Patents

Abstract

Hydrocarbon oils are freed from aromatics, hydroaromatics, and unsaturateds by countercurrent or batch treatment with one or more of the following solvents: ethyl oxalate, lactate, nitrate, or aceto-acetate; ethoxy ethyl acetate; methyl salicylate, formanilid, or propionate; butyl furoate, phenyl borate, triphenyl phosphate, benzyl phthalate; or mono-, di-, or tri-acetin, -propionin, or -butyrin. The selective solvents may be mixed with auxiliary solvents of the following kinds: (A) those miscible in any proportion with the selective solvents and with the oil treated; examples are aromatic and hydroaromatic hydrocarbons, and non-selective aliphatic and aromatic halogenated derivatives, e.g. chlorinated hydrocarbons; they increase the solvent power and so the amount of extract, leaving a more refined oil; (B) those miscible with the selective solvent but not or only slightly with the oil; examples are alcohols, water, and organic acids; they decrease the solvent power and so the amount of extract, which is desirable when treating naphthene-base oils; (C) those miscible only with the oil; examples are propane, butane, or other low-boiling paraffin; they sharpen the selective power. Dewaxing, before or after extraction, may be effected by chilling and centrifuging, filtering, or decanting, using as diluent a mixture of such proportions of a selective solvent and an auxiliary solvent of type A or C that the solvents do not separate from each other on chilling. The slack wax may be refined by treatment with the same or other solvent mixture. Recovery of the solvents from the raffinate, extract wax or dewaxed oil is effected by distillation or by extraction with solvents not dissolving the oils or wax. In examples, a dewaxed distillate is batchextracted at 86, 86, 120, and 160 DEG F. respectively with 1 vol. of ethyl acetoacetate each batch, and clay-treated at 450 DEG F., or with 1 vol. of ethyl lactate each batch at 120, 160, 194, and 230 DEG F. respectively.