Hydrocarbon isomerization process

Claim 1

THE PROCESS FOR UPGRADING A HYDROCARBON MIXTURE COMPRISING A STRAIGHT-CHAIN AND NON-STRAIGHT-CHAIN HYDROCARBONS BOILING WITHIN THE GASOLINE BOILING RANGE, WHICH COMPRISES (1) CONTACTING SAID MIXTURE IN THE VAPOR PHASE WITH A SOLID GRANULAR LEAN ADSORBENT ESSENTIALLY COMPRISING A PARTIALLY DEHYDRATED ZEOLITIC METALLO ALUMINO SILICATE HAVING PORES OF SUBSTANTIALLY UNIFORM DIAMETER BETWEEN ABOUT 4.5 A. AND ABOUT 5.5 A., SAID CONTACTING BEING EFFECTED AT A TEMPERATURE BELOW ABOUT 800*F. AND UNDER AT LEAST ATMOSPHERIC PRESSURE, WHEREBY THERE IS OBTAINED A RICH ADSORBENT CONTAINING ADSORBED STRAIGHT-CHAIN HYDROCARBON COMPONENTS OF SAID MIXTURE AND A RAFFINATE PRODUCT WHICH IS RICH IN NON-STRAIGHT-CHAIN COMPONENTS OF SAID MIXTURE; (2) SEPARATING SAID RAFFINATE PRODUCT FROM SAID RICH ADSORBENT; (3) REDUCING THE PRESSURE ON SAID RICH ADSORBENT TO A VALUE BETWEEN ABOUT 0.2 P.S.I.A. AND ABOUT 2.0 P.S.I.A. IN THE SUBSTANTIAL ABSENCE OF AN ADDED STRIPPING FLUID, WHEREBY THERE IS PRODUCED A DESORBED EXTRACT GAS COMPRISING DESORBED STRAIGHT-CHAIN HYDROCARBONS AND A PARTIALLY DESORBED ADSORBENT; (4) CONTACTING SAID PARTIALLY DESORBED ADSORBENT WITH HYDROGEN IN AN AMOUNT NO GREATER THAN THAT REQUIRED IN THE ISOMERIZATION OF SUBSEQUENT STEP (6) AND AT A PRESSURE BETWEEN ABOUT 0.2 P.S.I.A. AND ABOUT 2.0 P.S.I.A., WHEREBY THERE IS OBTAINED AT LEAN ADSORBENT AND AN EFFUENT GAS COMPRISING HYDROGEN AND STRAIGHT-CHAIN HYDROCARBONS; (5) ADMIXING SAID HYDROGEN-CONTAINING EFFUENT GAS WITH SAID EXTRACT GAS; AND (6) SUBJECTING THE RESULTING MIXTURE TO ISOMERIZING CONDITIONS IN THE PRESENCE OF AN ISOMERIZATION CATALYST, WHEREBY THE STRAIGHT-CHAIN HYDROCARBON COMPONENTS OF SAID RESULTING MIXTURE ARE ISOMERIZED TO BRANCHED-CHAIN HYDROCARBONS.