Method of refining crude oils having organic acidity

Abstract

The invention relates to a method of refining crude oils having high acidity by neutralising the organic acidity thereof. The inventive method consists in adding a nitrogenous compound to the crude oil. Said method is characterised in that a nitrogenous compound containing at least three carbon atoms, a secondary amine group and a hydric group is introduced at at least one point of the crude oil pre-treatment units upstream of, or in the atmospheric distillation unit.

1 . Process for refining by neutralisation of the organic acidity of crude oils having high acidity consisting of adding a nitrogenous compound to said crude oil, said process being characterized in that there is introduced in at least one point of the unit of pretreatment of crude oil upstream of or in the unit of atmospheric distillation a nitrogenous compound comprising at least three carbon atoms, a secondary amine group and a hydroxylated group.  
     
     
         2 . Process according to  claim 1  characterized in that the nitrogenous compounds used are chosen from the compounds of formula (I) below  
       
         
           
           
               
               
           
         
         in which Y is a linear or branched alkyl group comprising from 1 to 10 carbon atoms, optionally hydroxylated, and Z is chosen from the alkyl, hydroxyalkyl, and polyhydroxyalkyl, primary, secondary or tertiary amine groups and their hydroxylated and polyhydroxylated derivatives, the alkyl functions of these groups comprising from 1 to 10 carbon atoms.  
       
     
     
         3 . Process according to claims  1  and  2  characterized in that in the compound of formula (I), the Z is a group chosen from the hydroxyalkyl and polyhydroxyalkyl groups.  
     
     
         4 . Process according to  claims 1  to  3  characterized in that the compound of formula (I) is chosen from the group constituted by diethanolamine, dipropanolamine, dibutanolamine, N-propanol-2-ethanolamine, N-butanol-2-ethanolamine, N-butanol-3-ethanolamine, N-butanol-2-propanolamine, N-butanol-3-propanolamine, N-propanol-2-butanolamine, di-(methyl 1-hydroxy2)-propylamine, diisopropanolamine and di-(methyl2hydroxy2)-butylamine.  
     
     
         5 . Process according to  claim 4  characterized in that the compound of formula (I) is chosen from diethanolamine and diisopropanolamine.  
     
     
         6 . Process according to claims  1  and  2  characterized in that in the compound of formula (I), Z is an alkyl group comprising from 1 to 5 carbon atoms.  
     
     
         7 . Process according to  claim 6  characterized in that the compound of formula (I) is chosen from N-methyl-ethanolamine, N-propyl-ethanolamine,N-butylethanolamine, N-isobutylethanolamine, N-pentylethanolamine, N-methyl-propanolamine, N-isopentylethanolamine, N-propyl-propanolamine, N-butylpropanolamine, N-isobutylpropanolamine, N-pentylpropanolamine, N-isopentylpropanolamine, N-methyl-butanolamine, N-propyl-butanolamine, N-butylbutanolamine, N-isobutyl-butanolamine, N-pentylbutanolamine, N-isopentylbutanolamine, N-methyl-pentanolamine, N-propyl-pentanolamine, N-butylpentanolamine, N-isobutylpentanolamine, N-pentylpentanolamine and N-isopentylpentanolamine.  
     
     
         8 . Process according to claims  6  and  7 , characterized in that the compound of formula (I) is chosen from N-propylethanolamine and N-isobutylethanolamine.  
     
     
         9 . Process according to claims  1  and  2  characterized in that in the compound of formula (I), Z is chosen from the primary, secondary and tertiary amine groups and their monohydroxylated and polyhydroxylated derivatives.  
     
     
         10 . Process according to  claim 9  characterized in that the compound of general formula (I) is chosen from the group constituted by N-hydroxy-2-ethylhydrazine, N-hydroxy-2-ethylethylenediamine, N-hydroxy-2-ethyl-(1-3) propylenediamine, N,N′-bis(dihydroxy-2,3-propyl)amine and hydroxy-2-(1,3)propylenediamine.  
     
     
         11 . Process according to claims  9  and  10  characterized in that the compound of formula (I) is N-hydroxy-2-ethylethylenediamine.  
     
     
         12 . Process according to  claims 1  to  11  characterized in that the nitrogenous compound is introduced before the crude oil desalting unit, during preheating of the desalted crude oil, preferably before the heat exchangers or also in the distillation tower. 13 Process according to one of  claims 1  to  12  in which the crude oils have an organic acidity and total acidity higher than 0.5 mg KOH/g.