Verfahren zur Extraktion von aromatischen Kohlenwasserstoffen aus Mischungen von Kohlenwasserstoffen

摘要

In a process wherein the overall effect is to separate by solvent extraction alkyl naphthalenes from the remaining mainly aliphatic constituents of cycle oil, two extraction zones are used each containing the same solvent which is a mixture of dimethylformamide and water containing 5 to 18% preferably about 10% water. As shown, the cycle oil is fed to extraction zone 2 through line 7, the feed to extraction zone 1 along line 3 being a displacer oil, i.e. a mixture of xylenes and non-aromatic hydrocarbons, e.g. C6 to C8 paraffins, the mixture preferably having a boiling range at least 56 DEG C. lower than the cycle oil. The extract from extraction zone 2 contains the alkyl naphthalenes and is passed via line 10 to extraction zone 1 where the xylenes of the displacer oil displace the alkyl naphthalenes into the raffinate. The extract from extraction zone 1 is passed via line 6 to extraction zone 2 where the alkyl naphthalenes displace the xylenes into the raffinate. The raffinate from extraction zone 1 is passed via line 5 to distillation zone 3 where the alkyl naphthalenes are separated and removed, the other constituents being recycled to extraction zone 1 via line 31. The raffinate from extraction zone 2 is passed to distillation zone 4 where the non-aromatic constituents of the cycle oil are separated and removed, the remaining constituents, mainly xylenes and some solvent, are recycled to extraction zone 1 through line 31.