Patent ID: 8378164
Filing Date: 2013-02-19
Classification: B01D,C07C,C10G

Abstract:
1. A process for obtaining aromatic hydrocarbons selected from benzene, toluene, xylene and ethylbenzene and mixtures thereof from a hydrocarbon mixture which additionally comprises nonaromatic hydrocarbons and high boilers, comprising the steps of (A) providing a hydrocarbon mixture a1 and an extractive solvent a2 composed of N-formylmorpholine, (B) extractively distilling the hydrocarbon mixture a1 with the extractive solvent to obtain a mixture b1 of extractive solvent and the aromatic hydrocarbons, said mixture comprising high boilers, and a mixture b2 comprising nonaromatic hydrocarbons, (C) distilling the mixture b1 of extractive solvent and aromatic hydrocarbons obtained in step (B) to obtain one or more fractions c1 composed of aromatic hydrocarbons and the extractive solvent c2 which comprises high boilers, (D) removing a substream d1 from the extractive solvent c2 and recycling the extractive solvent c2 into the extractive distillation (B), (E) extracting the substream d1 of the extractive solvent with water to obtain an aqueous extract phase e1 essentially free of high boilers and an organic phase e2 comprising the high boilers, (F) distilling the aqueous extract phase e1 and recovering the extractive solvent a2 in purified form, and recycling the extractive solvent into the extractive distillation (B), which comprises removing a substream e2′ from the organic phase e2 comprising the high boilers and recycling it into the extraction of step (E), the amount of the organic phase e2′ thus circulated being such that, where the substream d1 composed of extractive solvent comprising high boilers, water and circulated stream e2′ is dispersed, the aqueous extract phase e1 essentially freed of high boilers forms as a disperse phase, and the organic phase composed of high boilers e2 form as a continuous phase.