Method for softening sulfide-type compounds of an olefinic gasoline

Method for reducing the content of sulfide-type compounds of formula R1-S—R2, with R1 and R2 selected from among the methyl (CH3) and ethyl (C2H5) radicals, of a gasoline that contains diolefins, monoolefins, and sulfur, in which:

• A) In a first reactor, the gasoline is brought into contact with hydrogen and a catalyst A that comprises at least one metal of group VIb and at least one non-noble metal of group VIII that are deposited on a substrate, with step A being carried out at a temperature in the reactor of between 60° C. and 150° C. with an hourly volumetric flow rate (VVH) of between 1 h−1 and
• 10 h−1, a pressure of between 0.5 and 5 MPa, and with a volumetric ratio of added H2/gasoline feedstock of between 1 to 40 normal liters of hydrogen per liter of gasoline (vol/vol), in such a way as to produce an effluent at a temperature T1 of between 60° C. and 150° C. and having a lower diolefin content than that of the starting gasoline;
• B) The effluent that is obtained from the first reactor is heated in a heating device at a temperature T2 with a temperature difference ΔT (T2-T1) of between 10° C. and 100° C.;
• C) In a second reactor, the effluent that is heated at the temperature T2 is brought into contact with a catalyst C that comprises at least one metal of group VIb and at least one non-noble metal of group VIII that are deposited on a substrate and optionally with hydrogen, and in which:
• Step C is carried out with an hourly volumetric flow rate (VVH) of between 1 h−1 and 10 h−1, a pressure of between 0.5 and 5 MPa, with a volumetric ratio of added H2/gasoline feedstock of between 0 to 40 normal liters of hydrogen per liter of gasoline (vol/vol), in such a way as to produce an effluent from the second reactor that has a content of sulfide-type compounds of formula R1-S—R2, with R1 and R2 selected from among the methyl (CH3) and ethyl (C2H5) radicals, lower than that of the starting gasoline.