Combination process for high-octane naphtha production

Claim 1

A COMBINATION PROCESS FOR PRODUCING HIGH OCTANE GASOLINE BLENDING STOCKS FROM LOWER OCTANE NAPHTHA, WHICH PROCESS COMPRISES CHARGING SAID NAPHTHA TO A FRACTIONATION ZONESEPARATING SAID NAPHTHA IN SAID ZONE INTO AT LEAST A FIRST NAPHTHA FRACTION RICH IN HYDROCARBONS BOILING BELOW ABOUT 170-180*F. AND A SECOND NAPHTHA FRACTION RICH IN HYDROCARBONS BOILING ABOVE ABOUT 170-180*F., HYDROFORMING SAID SECOND NAPHTHA FRACTION IN A HYDROFORMING ZONE IN THE PRESENCE OF PLATIMUM-ALUMINA HYDROFORMING CATALYST, WHEREBY THERE IS PRODUCED A NET AMOUNT OF HYDROGEN AND A HYDROFORMATE HAVING A HIGHER OCTANE THAN SAID SECOND NAPHTHA FRACTION, RECYCLING A FIRST PORTION OF SAID HYDROGEN TO SAID HYDROFORMING ZONE, SEPARATING SAID HYDROFORMATE INTO A FIRST HYDROFORMATE FRACTION RICH IN HYDROCARBONS BOILING BELOW ABOUT 170-180*F. AND A SECOND HYDROFORMATE FRACTION RICH IN HYDROCARBONS BOILING ABOVE ABOUT 170180*F. HAVING A HIGHER OCTANE THAN SAID SECOND NAPHTHA FRACTION AND SUITABLE FOR USE AS A GASOLINE BLENDING STOCK, CHARGING SAID FIRST NAPHTHA FRACTION AND SAID FIRST HYDROFORMATE FRACTION TO A SEPARATION ZONE, SEPARATING FROM THE CHARGE TO SAID SEPARATION ZONE AT LEAST A SUBSTANTIAL PORTION OF THE NORMAL PENTANE AND NORMAL HEX ANE IN THE CHARGE TO SAID SEPARATION ZONE, WITHDRAWING FROM SAID SEPARATION ZONE AS A GASOLINE BLENDING STOCK THE REMAINING HYDROCARBONS FROM THE CHARGE TO SAID SEPARATION ZONE, CHARGING SAID NORMAL PENTANE AND NORMAL HEXANE AND A SECOND PORTION OF SAID HYDROGEN TO AN ISOMERIZATION ZONE MAINTAINED UNDER ISOMERIZING COMDITIONS ADAPTED TO CONVERT AT LEAST A SUBSTANTIAL PROPORTION OF SAID NORMAL PENTANE AND NORMAL HEXANE TO HIGER OCTANE ISOMERS THEREOF, AND CHARGING THE HYDROCARBON EFFLUENT FROM SAID ISOMERIZATION ZONE TO SAID SEPARATION ZONE.