Separation of aromatic hydrocarbons by solvent extraction followed by azeotropic distillation of the extract phase

Claim 1

IN A PROCESS FOR SEPARATION BENZENE FROM A C6-C7 HYDROCARBONS FRACTION CONTAINING BENZENE IN CONCENTRATIONS OF AT LEAST ABOUT 1 PERCENT IN ADMIXTURE WITH OTHER HYDROCARBONS, THE IMPROVEMENT WHICH COMPRISES MIXING SAID FRACTION WITH ABOUT 100 TO 400 PERCENT BY WEIGHT OF A LIQUID AMMONIA SOLVENT IN A LIQUID EXTRACTION ZONE, WITH DRAWING FROM SAID EXTRACTION ZONE A RAFFINATE PHASE RELATIVELY RICH IN NON-AROMATIC HYDROCARBONS, ALSO WITHDRAWING FROM SAID EXTRACTION ZONE A LIQUID SOLVENT EXTRACT CONTAINING IN ITS HYDROCARBON PORTION ABOUT 30 TO 90 PERCENT BENZENE AND CORRESPONDINGLY 70 TO 10 PERCENT NON-AROMATIC HYDROCARBONS, BOILING THE LIQUID EXTRACT IN A DISTILLATION ZONE AT A PRESSURE OF ABOUT 100 TO 400 P.S.I.A, WITHDRAWING FROM SAID DISTILLATION ZONE AN OVERHEAD FRACTION-CONTAINING AN AZEOTROPIC MIXTURE OF AMMONIA AND NON-AROMATIC HYDROCARBONS, RECYCLING SAID OVERHEAD FRACTION TO A LOWER PORTION OF THE LIQUID EXTRACTION ZONE, AND ALSO WITHDRAWING FROM SAID DISTILLATION ZONE A RESIDUE FRACTION CONTAINING CONCENTRATED BENZENE.