Process for desulphurising and dewaxing a hydrocarbon feedstock boiling in the gasoil boiling range

Abstract

A process for desulphurising and dewaxing a hydrocarbon feedstock boiling in the gasoil boiling range to obtain a desulphurised and dewaxed gasoil fraction for use in an ultra low sulphur diesel fuel, comprising the following steps: (a) hydrodesulphurising the hydrocarbon feedstock boiling in the gasoil boiling range by contacting the feedstock in a hydrodesulphurisation reaction zone at elevated temperature and pressure, in the presence of hydrogen, with a hydrodesulphurisation catalyst and withdrawing a liquid hydrodesulphurisation effluent from the reaction zone; (b) catalytically dewaxing the liquid hydrodesulphurisation effluent to obtain a desulphurised and dewaxed gasoil fraction by contacting the liquid hydrodesulphurisation effluent, at elevated temperature and pressure in the presence of hydrogen, with a stacked bed of catalysts having a first upstream bed of noble metal containing hydrofinishing catalyst and a second downstream bed of noble metal containing dewaxing catalyst, wherein hydrogen and the liquid effluent are countercurrently supplied to the stacked bed of catalysts.

1 . A process for desulphurising and dewaxing a hydrocarbon feedstock boiling in the gasoil boiling range to obtain a desulphurised and dewaxed gasoil fraction for use in an ultra low sulphur diesel fuel, comprising the following steps: 
 (a) hydrodesulphurising the hydrocarbon feedstock boiling in the gasoil boiling range by contacting the feedstock in a hydrodesulphurisation reaction zone at elevated temperature and pressure, in the presence of hydrogen, with a hydrodesulphurisation catalyst and withdrawing a liquid hydrodesulphurisation effluent from the reaction zone;    (b) catalytically dewaxing the liquid hydrodesulphurisation effluent to obtain a desulphurised and dewaxed gasoil fraction by contacting the liquid hydrodesulphurisation effluent, at elevated temperature and pressure in the presence of hydrogen, with a stacked bed of catalysts having a first upstream bed of noble metal containing a hydrofinishing catalyst and a second downstream bed of noble metal containing a dewaxing catalyst, wherein hydrogen and the liquid effluent are countercurrently supplied to the stacked bed of catalysts.    
   
   
       2 . A process according to  claim 1 , wherein the volume of said first upstream bed of hydrofinishing catalyst is smaller than the volume of said second downstream bed of dewaxing catalyst.  
   
   
       3 . A process according to  claim 2 , wherein said hydrodesulphurisation catalyst comprises a cobalt compound and a molybdenum compound as hydrogenation compounds.  
   
   
       4 . A process according to  claim 3 , wherein said hydrocarbon feedstock is contacted with the hydrodesulphurisation catalyst in step (a) at a temperature in the range of from 300 to 400° C., and at a pressure in the range of from 20 to 80 bar (absolute).  
   
   
       5 . A process according to  claim 4 , wherein the dewaxing catalyst comprises a noble metal as hydrogenation component, a dealuminated silica-alumina zeolite and a refractory oxide binder material.  
   
   
       6 . A process according to  claim 5 , wherein the dealuminated silica-alumina zeolite is dealuminated ZSM-12.  
   
   
       7 . A process according to  claim 6 , wherein the temperature in step (b) is in the range of from 250 to 400° C.  
   
   
       8 . A process according to  claim 7 , wherein the temperature in the second downstream bed is in the range of from 300 to 340° C.  
   
   
       9 . A process according to  claim 8 , wherein the pressure in step (b) is in the range of from 20 to 80 bar (absolute).  
   
   
       10 . A process according to  claim 9 , wherein the liquid hydrodesulphurisation effluent has a sulphur content of at most 150 ppmw.  
   
   
       11 . A process according to  claim 10 , wherein the liquid hydrodesulphurised effluent has a nitrogen content of at most 50 ppmw.  
   
   
       12 . A process according to  claim 11 , wherein the desulphurised and dewaxed gasoil fraction obtained in step (b) is not subjected to a hydrofinishing step before being used in a ultra low sulphur diesel fuel.