GB693237A - Hydrocarbon separation process - Google Patents

Abstract

A hydrocarbon mixture is subjected to a primary separation to yield an aromatic-rich and an aromatic-lean fraction, the aromatic-lean fraction is subjected to selective adsorption to remove substantially all aromatics, the solid adsorbent after use is regenerated by washing with the aromatic-lean fraction at elevated temperature and the effluent from the solid adsorbent during regeneration is recycled to the primary separation. Hydrocarbon mixtures mentioned include petroleum distillates, such as kerosene, and cracked and reformed naphthas. The aromatic-rich fraction obtained may constitute a toluene or xylene of high purity. The primary separation may be solvent extraction with liquid sulphur dioxide, furfural or nitrobenzene as the solvent, a "Duosol" extraction employing propane and phenol-cresol mixture as the solvent, an extractive distillation with a solvent such as phenol, or an azeotropic distillation using for example methyl ethyl ketone and water to form the azeotrope. Adsorbents mentioned are silica gel, alumina gel, silicaalumina gel and activated carbon or charcoal. In the examples, petroleum kerosene distillate is first solvent-extracted with liquid sulphur dioxide and then contacted with silica gel according to the above-described process.ALSO:A hydrocarbon mixture is subjected to a primary separation to yield an aromatic-rich and an aromatic-lean fraction, the aromatic-lean fraction is subjected to selective adsorption to remove substantially all aromatics, the solid adsorbent after use is regenerated by washing with the aromatic-lean fraction at elevated temperature and the effluent from the solid adsorbent during regeneration is recycled to the primary separation. Hydrocarbon mixtures mentioned are petroleum distillates, such as p kerosene, Diesel fuel and lubricating oil distillates, and cracked and reformed naphthas. Stocks suitable for the production of spray oils, cosmetic oils, medicinal oils and other white oils may be subjected to the process to produce substantially aromatic-free products which require no acid-treating step in order to meet commercial specifications. Where lubricating oils are treated the lubricating oil raffinate obtained from the primary separation may be diluted with a light hydrocarbon liquid before being subjected to selective adsorption. Suitable light hydrocarbons are low boiling paraffins such as pentane or isopentane or a light gasoline. The primary separation may be solvent extraction with liquid sulphur dioxide, furfural or nitrobenzene as the solvent, a "Duosol" extraction employing propane and phenolcresol mixture as the solvent, an extractive distillation with a solvent such as phenol, or an azeotropic distillation using for example methyl ethyl ketone and water to form the azeotrope. Adsorbents mentioned are silica gel, alumina gel, silica-alumina gel and activated carbon or charcoal. In the examples, petroleum kerosene distillate is first solvent-extracted with liquid sulphur dioxide and then contacted with silica gel according to the above-described process.