| 摘要 |
Styrene is obtained by distilling a mixture containing ethylbenzene, xylenes and at least 0.3% by wt. of non-aromatic hydrocarbons boiling in the same range in a column or columns containing at least 150 stages at a reflux ratio of at least 40: 1 to obtain an overhead distillate containing ethylbenzene and non-aromatic hydrocarbons which is dehydrogenated and styrene recovered. The distillation is effected as described in U.S.A. Specification 2,959,626. Unconverted ethylbenzene from the dehydrogenation is recycled and build up of non-aromatics is prevented by removing a bleed stream, by distillation of the recycle alone or together with the ethylbenzene distillate feed or by subjecting all or part of the recycle, together with the ethylbenzene distillate feed if desired, to a solvent extraction process. The feed to the process preferably contains less than 5% by weight of non-aromatics and the combined fresh and recycle feed to the dehydrogenation less than 20%. Dehydrogenation is effected conventionally e.g. using an alkali promoted iron oxide catalyst and styrene is recovered by distillation under reduced pressure. |
