Method for desulphurizing a hydrocarbon mixture

Abstract

Process for the desulphurization of a mixture of hydrocarbons containing sulphur compounds, comprising a step of oxidation by means of hydrogen peroxide, acetic acid and an acid catalyst in order to oxidize the sulphur compounds, in which the acid catalyst contains an acid solid chosen from cation-exchange resins having a pKa of less than or equal to 4, from solids based on silicon oxide additionally containing a trivalent metal, and from particles of inorganic solid on which acidic organic groups are grafted such that the particles thus grafted have a pKa of less than or equal to 4.

1 . Process for the desulphurization of a mixture of hydrocarbons containing sulphur compounds, comprising a step of oxidation by means of hydrogen peroxide, acetic acid and an acid catalyst in order to oxidize the sulphur compounds, in which the acid catalyst contains an acid solid chosen from cation-exchange resins having a pKa of less than or equal to 4, from solids based on silicon oxide additionally containing a trivalent metal, and from particles of inorganic solid on which acidic organic groups are grafted such that the particles thus grafted have a pKa of less than or equal to 4.  
     
     
         2 . Process according to  claim 1 , characterized in that the acid catalyst contains a cation-exchange resin having a pKa of less than or equal to 4 and is chosen from fluorinated resins where the hydrogen atoms of the hydrocarbon backbone have been partially or completely substituted with fluorine atoms and which contain sulphonic and/or carboxylic groups.  
     
     
         3 . Process according to  claim 2 , characterized in that the acid catalyst contains particles of resin which are dispersed in an inorganic matrix.  
     
     
         4 . Process according to  claim 2  or  3 , characterized in that a quantity of acid catalyst is used such that the number of mol of protons from the carboxylic and/or sulphonic groups per kg of aqueous phase with which the catalyst is in contact is from 0.001 to 0.8.  
     
     
         5 . Process according to  claim 1 , characterized in that the acid catalyst contains a solid based on silicon oxide additionally containing aluminium and in which the silicon/aluminium molar ratio in the solid is from 3, to 200, and in that the solid is chosen from zeolites, clays and amorphous solids based on silicon oxide additionally containing aluminium.  
     
     
         6 . Process according to  claim 5 , characterized in that the solid contains sulphonic and/or carboxylic functionalities.  
     
     
         7 . Process according to  claim 5  or  6 , characterized in that a quantity of acid catalyst is used such that the number of mol of aluminium per kg of aqueous phase with which the catalyst is in contact is from 0.001 to 0.8.  
     
     
         8 . Process according to  claim 1 , characterized in that the acid catalyst contains particles of inorganic solid on which acid organic groups are grafted such that the particles thus grafted have a pKa of less than or equal to 4, the inorganic solid being silicon oxide and the acid organic groups being chosen from carboxylic and/or sulphonic groups.  
     
     
         9 . Process according to  claim 8 , characterized in that a quantity of acid catalyst is used such that the number of mol of protons from the carboxylic and/or sulphonic groups per kg of aqueous phase with which the catalyst is in contact is from 0.001 to 0.8.  
     
     
         10 . Process according to any one of the preceding claims, characterized in that the oxidation is carried out at a temperature of 0 to 100° C. and using a quantity of hydrogen peroxide such that, in the oxidation reaction medium, the molar ratio of the hydrogen peroxide relative to the sulphur present in the mixture of hydrocarbons is from 1 to 5 000, a quantity of acetic acid such that, in the oxidation reaction medium, the molar ratio between the acetic acid and the hydrogen peroxide is 0.01 to 4, and in that a volume of aqueous phase essentially containing water, hydrogen peroxide, part of the acetic acid and part of the peracetic acid formed in situ is brought into contact with the mixture of hydrocarbons such that the ratio of the volumes of this aqueous phase and of the mixture of hydrocarbons is from 0.01 to 0.5.  
     
     
         11 . Process according to any one of the preceding claims, characterized in that the oxidation is preceded by one or more hydrodesulphurization steps and in that the oxidation is followed by one or more steps of separating the oxidized sulphur compounds.