processes for the recovery of styrene and xylene from oil and new products obtained (craquee

摘要

1,274,784. Extractive distillation; catalytic hydrogenation. TORAY INDUSTRIES Inc. 10 Feb., 1970 [17 Feb., 1969; 26 Aug., 1969], No. 6208/70. Heading C5E. Styrene and xylene are separated from hydrocarbon fractions by subjecting the fractions to extractive-distillation with a dialkylacetamide, dialkylsulphoxide, an alkylene carbonate, a lactone, phenol, m-cresol, aniline or an alkylaniline as solvent to obtain xylene in the distillate and styrene as a residue. The hydrocarbon fraction can be an oil produced in the thermal cracking of naphtha to ethylene and containing hydrocarbons having 5 to 9 carbon atoms. This oil can be distilled at atmospheric pressure in one or two separate columns to remove materials having up to 7 or more than 9 carbon atoms and the remaining material is passed to the extractive distillation. 10-500 p.p.m. of hydroquinone, t-butylcatechol, phenothiazine or sulphur can be included in the extractive distillation to inhibit polymerization of styrene. The extractive distillation can be carried out at below 120‹ C. and below 200 mm. Hg absolute with a reflux ratio between 10 and 30 in one column or in two columns. When two columns are used the extract solvent is fed to the tops of each column, the feed is passed to the middle of the first column and the bottoms from the first column is fed to the middle of the second column. The top fraction from the extractive distillation can be mixed with the up to C 7 material distilled from the feed and the mixture hydrogenated at 10-200 kg./sq. cm. abs. and 100- 400‹ C. using a catalyst of Co, Mo and/or W to produce ethylbenzene and o-, m- and p-xylenes.