Desulfurization of a charge containing thiophene or thiophenic components comprises eliminating the diolefins in the charge, fractionating the charge in a distillation zone into a heavy fraction which is then desulfurized and a lighter fraction including the thiophene and/or thiophenic components, and alkylating the thiophene and/or thiophenic components using at least one olefin Preferred Features: The alkylated products are recycled to the distillation zone to be included in the heavy fraction, or are sent directly to be included in the heavy fraction. The olefin used is present on at least one tray in the distillation zone. The charge is catalytic cracking effluent or vapor cracking effluent. The alkylation catalyst is zeolites, silica- aluminas or ion exchange resins. Desulfurizing with boiling points below 350 deg C, containing 3-90 wt.% olefins, and 5 ppm and 3 wt.% sulfur comprises the use of at least one distillation unit, at least one alkylation unit and at least one hydrotreatment unit. The distillation can be before or during the alkylation and the hydrotreatment is after the distillation. The sulfur components are alkylated on an acid catalyst in the presence of olefins with 2-10 carbon atoms, with the molecular ratio of olefin to sulfur being 0.1-1000 moles per mole, preferably 0.5-500 moles per mole. The alkylation unit operates at a pressure of at least 5 bars. Nitrous components are at least partially removed from the charge before alkylation, upstream or downstream of the distillation.
La présente invention concerne un enchaînement d'étapes destinées à désulfurer une essence par exemple de craquage catalytique comportant l'élimination des composés thiophéniques par alkylation de ces composés. Une élimination de composés azotés est effectuée en amont de l'étape d'alkylation.