Process for deep desulfurization by adsorption of a gas oil-type hydrocarbon fraction

Abstract

The invention describes a process for deep desulfurization of a gas oil-type hydrocarbon fraction by adsorption in the presence of hydrogen on a solid that contains zinc oxide and a promoter in oxide form. Said adsorbent solid is regenerated by a controlled combustion with dilute air.

1 . Process for deep desulfurization of a hydrocarbon fraction with a distillation interval of between 150° C. and 450° C. and of any chemical composition, containing less than 500 ppm of sulfur, for producing a desulfurized fraction that contains less than 10 pm of sulfur, preferably less than 5 ppm and even more preferably less than 1 ppm, whereby said process is characterized in that an adsorbent solid that contains at least one zinc oxide and a promoter in the form of another metal oxide are used, whereby this metal is different from zinc, zinc oxide and the promoter are deposited on a porous substrate based on silica or alumina or a mixture of silica and alumina, said adsorbent solid is brought into contact with the feedstock that is to be treated at a temperature of greater than 200° C. and in the presence of hydrogen until the saturation of said solid in sulfur-containing compounds is completed, then said adsorbent solid is regenerated by a controlled combustion with dilute air so as to regain the oxide form of said adsorbent solid that is then reintroduced in adsorption phase.  
   
   
       2 . Process for deep desulfurization of a hydrocarbon fraction according to  claim 1 , wherein the zinc that is contained in the adsorbent solid represents more than 1% by weight of the adsorbent solid, preferably more than 5% by weight of the adsorbent solid, and even more preferably more than 10% by weight of the adsorbent solid.  
   
   
       3 . Process for deep desulfurization of a hydrocarbon fraction according to  claim 1 , wherein the promoter that is contained in the adsorbent solid is selected from among the following metal oxides: titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, molybdenum, and preferably is selected from among the iron or copper oxides.  
   
   
       4 . Process for deep desulfurization according to  claim 1 , wherein the promoter that is contained in the adsorbent solid represents from 1 to 40% by weight of the adsorbent solid and preferably from 10 to 20% by weight of the adsorbent solid.  
   
   
       5 . Process for deep desulfurization according to  claim 1 , wherein the porous substrate has a specific surface area that is greater than 50 m 2 /g and preferably greater than 100 m 2 /g.  
   
   
       6 . Process for deep desulfurization according to  claim 1 , wherein the temperature in the adsorption phase is greater than 200° C., preferably greater than 300° C., and even more preferably greater than 350° C.  
   
   
       7 . Process for deep desulfurization according to  claim 1 , wherein the operating pressure in the adsorption phase is between 1 and 60 bar.  
   
   
       8 . Process for deep desulfurization according to  claim 1 , wherein the volumetric ratio of the introduced hydrogen, taken under the input conditions of the adsorber, to the feedstock to be treated is between 5 and 400, and preferably between 50 and 300.  
   
   
       9 . Process for deep desulfurization according to  claim 1 , wherein the porous substrate exhibits both a mesoporosity with a pore volume of between 0.1 and 0.6 ml/g, and a macroporosity with a pore volume of between 0.1 and 0.6 ml/g.  
   
   
       10 . Process for deep desulfurization according to  claim 9 , wherein the mesoporosity pore volume is preferably between 0.2 and 0.4 ml/g, and the macroporosity pore volume is preferably between 0.2 and 0.4 ml/g.  
   
   
       11 . Process for deep desulfurization according to  claim 1 , wherein the zinc oxide is incorporated in the substrate in the form of zinc aluminate or zinc silicate or zinc silicoaluminate.  
   
   
       12 . Process for deep desulfurization according to  claim 1 , wherein the feedstock that is to be treated consists of a hydrocarbon flow that is obtained from a standard hydrodesulfurization unit, provided that the sulfur content of said flow is less than 500 ppm.  
   
   
       13 . Process for deep desulfurization according to  claim 1 , wherein the feedstock that is to be treated consists of a hydrocarbon flow that is obtained from a hydrodesulfurization unit, provided that the sulfur content of said flow is less than 500 ppm, and the temperature of said flow is greater than 200° C.  
   
   
       14 . Process for deep desulfurization by adsorption on an adsorbent solid of oxide form, a hydrocarbon fraction of the gas oil type, containing less than 500 ppm by weight of sulfur-containing compounds, wherein the yield by weight of the desulfurization is greater than 95% and preferably greater than 97%.  
   
   
       15 . Process for deep desulfurization of a hydrocarbon fraction according to  claim 1 , wherein the particles of adsorbent solid have a SAUTER diameter of between 500 microns and 6 mm and preferably of between 1 mm and 5 mm.  
   
   
       16 . Process for deep desulfurization of a hydrocarbon fraction according to  claim 14 , wherein the particles of adsorbent solid have a SAUTER diameter of between 500 microns and 6 mm and preferably of between 1 mm and 5 mm.