Isomerization of saturated hydrocarbons

Claim 1

A PROCESS FOR THE ISOMERIZATION OF AN ISOMERIZABLE SATURATED HYDROCARBON FRACTION, CHARACTERIZED BY AN AVERAGE MOLECULAR WEIGHT GREATER THAN ABOUT 80, TO PRODUCE A COMPOSITE HYDROCARBON FRACTION HAVING AN F-1+3 CC. OCTANE NUMBER OF AT LEAST 100, SAID ISOMERIZATION BEING CARRIED OUT IN THE PRESENCE OF AN ISOMERIZATION CATALYST, WHICH COMPRISES PASSING TO A FIRST FRACTIONATION ZONE SAID FIRST MENTIONED HYDROCARBON FRACTION IN COMBINATION WITH LIQUID PHASE ISOMERIZATION ZONE EFFLUENT PRODUCED AS HEREINAFTER DESCRIBED, FRACTIONATING SAID HYDROCARBONS TO PRODUCE A SUBSTANTIALLY NAPHTHENE-FREE OVERHEAD HYDROCARBON FRACTION AND TO PRODUCE A SUBSTANTIALLY PURE CYCLICS HYDROCARBON BOTTOMS FRACTION, REMOVING SAID SUBSTANTIALLY PURE CYCLICS HYDROCARBON BOTTOMS FRACTION HAVING AN F-1+3 CC. OCTANE NUMBER OF AT LEAST 100 AS ONE PRODUCT FROM THE PROCESS, PASSING SAID SUBSTANTIALLY NAPHTHENE-FREE OVERHEAD HYDROCARBON FRACTION FROM SAID FIRST FRACTIONATION ZONE TO A SECOND FRACTIONATION ZONE AS FREED THEREFOR, FRACTIONATING SAID HYDROCARBONS TO PRODUCE AN OVERHEAD FRACTION CHARACTERIZED BY A MAJOR PROPORTION OF HYDROCARBONS WITH AT LEAST TWO METHYL SUBSTITUTENTS PER MOLECULE AND AN F-1+3 CC. OCTANE NUMBER OF AT LEAST 100 AND TO PRODUCE A BOTTOMS HYDROCARBON FRACTION, REMOVING SAID OVERHEAD HYDROCARBON FRACTION AS A SECOND PRODUCT FROM THE PROCESS, PASSING SAID LAST MENTIONED BOTTOMS HYDROCARBON FRACTION TO AN ISOMERIZATION ZONE WHEREIN LOW OCTANE NUMBER HYDROCARBONS ARE ISOMERIZED TO HIGHER OCTANE NUMBER HYDROCARBONS, RECYCLING THE ISOMERIZATION ZONE EFFLUENT TO THE FIRST MENTIONED FRACTIONATION ZONE AS AFORESAID TO RECOVER THE HIGHER OCTANE NUMBER HYDROCARBONS THEREFROM AS PRODUCT AND TO SEPARATE LOW OCTANE NUMBER HYDROCARBONS AS AFORESAID FOR REUSE AND INTERNAL RECYCLE OF SAID PROCESS, BLENDING SAID SECOND PRODUCT WITH SAID CYCLICS HYDROCARBON BOTTOMS FRACTION AND RECOVERING THE RESULTANT BLEND AS SAID COMPOSITE FRACTION.