method for the separation of a mixture of aromatic and non aromatic hydrocarbons (by extraction and extractive distillation with a selective solvent of sulfolane type.

摘要

1301887 Extractive distillation SHELL INTERNATIONALE RESEARCH MAATSCHAPPIJ NV 5 May 1970 [7 May 1969] 21571/70 Heading C5E A feed 1 containing a selective solvent and aromatic and non-aromatic hydrocarbons which boil at a lower temperature than the selective solvent is separated by extractive distillation at 2 into a stream 3 comprising non-aromatics and a secondary solution 4 comprising the selective solvent and aromatic hydrocarbons and the stream 4 is separated by distillation at 5 into a stream 6 of aromatic hydrocarbons and a stream 9 comprising the selective solvent and some aromatic hydrocarbons which is recycled to the extractive distillation. Suitable selective solvents are glycols, piperidone, sulpholone and N-methyl pyrrolidone, e.g. the feed 1 is suitably the extract phase resulting from the liquid/ liquid extraction of kerosene, pyrolyses gasoline or catalytic reformate. The content of aromatics in the stream 9 is suitably 5-50% of that in the stream 4 and the weight of the recycle 9 is at least 25% of that of the solution subjected to extractive distillation at 2. A stream 7 of lean solvent is recovered or a part of the stream 9 can be subjected to a second distillation (Fig. 2, not shown) to separate pure solvent. The distillation of the secondary solution can be carried out with steam stripping (Fig. 3, not shown). The distillations 2 and 5 can be carried out in a single column using a draw-off tray which is impermeable to liquid and permcable to vapour.