Recovery of aromatic hydrocarbon by extractive distillation with anhydrous liquid propylene carbonate

Claim 1

A PROCESS FOR THE RECOVERY OF VERY PURE AROMATIC HYDROCARBONS FROM A VAPORIZED MIXTURE OF SAID AROMATIC HYDROCARBONS WITH PARAFFINIC AND NAPHTHENIC HYDROCARBONS BY AN EXTRACTIVE DISTILLATION COMPRISING INTRODUCING SAID VAPORIZED MIXTURE INTO THE MIDDLE OF A DISTILLATION COLUMN; ADDING AT THE HEAD OF SAID COLUMN PRACTICALLY ANHYHDROUS LIQUID PROPYLENE CARBONATE IN A RATIO BY VOLUME OF TWO TO SIX PARTS OF LIQUID PROPYLENE CARBONATE TO ONE PART OF AROMATIC HYDROCARBONS, CONTACTING SAID VAPORIZED MIXTURE WITH SAID PROPYLENE CARBONATE IN SAID DISTILLATION COLUMN AT A TEMPERATURE BETWEEN 115 AND 134*C. SUCH THAT SAID AROMATIC HYDROCARBONS DISSOLVE IN SAID PROPYLENE CARBONATE AND SAID PARAFFINIC AND NAPHTHENIC HYDROCARBONS ARE DISCHARGED THROUGH THE HEAD OF SAID COLUMN, WITHDRAEING SAID LIQUID PROPYLENE CARBONATE CONTAINING SAID AROMATIC HYDROCARBONS FROM THE BOTTOM OF SAID COLUMN, SEPARATING SAID AROMATIC HYDROCARBONS FROM SAID PROPYLENE CARBONATE BY A SIMPLE DISTILLATION AND RETURNING SAID LIQUID PROPYLENE CARBONATE TO THE HEAD OF SAID COLUMN FOR EXTRACTIVE DISTILLATION OF ADDITIONAL AMOUNTS OF SAID MIXTURES.