Prolongation of sieve capacity by controlled desulfurization

Claim 1

A PROCESS FOR SEPARATING STRAIGHT-CHAIN HYDROCARBONS FROM FEEDSTOCKS OF PETROLEUM FRACTIONS BOILING BETWEEN 85-400*C. CONTAINING THE STRAIGHT-CHAIN HYDROCARBONS IN ADMIXTURE WITH BRANCHED-CHAIN AND/OR CYCLIC HYDROCARBONS BY EXTRACTION WITH A 5 A. MOLECULAR SIEVE WHEREIN THE FEEDSTOCK CONTAINING MORE THAN 1% WEIGHT SULFUR HYDROCATALYTIC IS FIRST SUBJECTED TO A DESULFURIZATION STEP IN WHICH THE SULFUR CONTENT IS REDUCED TO A VALUE WITHIN THE RANGE 0.002 TO 0.015% WEIGHT BY HYDROCATATION STEP IN WHICH THE SULFUR CONTENT IS REDUCED TO A VALUE WITHIN THE RANGE OF 0.002 TO 0.015% WEIGHT BY HYDROCATALYTIC DESULFURIZATION IN THE PRESENCE OF A CATALYST COMPRESING AT LEAST ONE METAL SELECTED FROM GROUPS VIA AND VIII OF THE PERIODIC TABLE SUPPORTED ON A REFRACTORY OXIDE, AT A TEMPERATURE BETWEEN 300-480*C., A PRESSURE BETWEEN 50-2000 P.S.I.G., A SPACE VELOCITY BETWEEN 0.5-20 V./V./HR. AND A HYDROGEN FLOW RATE BETWEEN 50-10,000 S.C.F./B.