Process for aromatic hydrogenation and cetane value increase of middle-distillate feedstocks

Abstract

The instant invention pertains to a process for treating a feed, for example a Light Cycle Oil (LCO), having a high content of S and/or N impurities and/or a high content of aromatics, comprising the following steps, in particular in such an order a step of desulphurisation (HDS) and denitrification (HDN) of a feed, in particular LCO, is passed in presence of hydrogen over a catalyst, containing metals of the group VI B and VIII, leading to an effluent, optionally a step of stripping of the effluent, at least a subsequent step for dearomatization (HDA) in which at least a portion of the effluent, optionally stripped, is passed in presence of hydrogen over a catalyst comprising a combination of platinum and palladium supported on a carrier comprising silica-alumina dispersed in an alumina binder wherein the amount of alumina binder is 5-50 wt. % based on the total weight of the silica-alumina and alumina binder present in the carrier and wherein the silica-alumina comprises 5-50 wt. % of alumina based on the weight of the silica-alumina, and recovering the final load obtained, the use of a specific catalyst and a process for preparing diesel comprising the step of mixing the final effluent obtained by a process of the invention.

1 . Process for treating a feed, for example a Light Cycle Oil (LCO), having a high content of S and/or N impurities and/or a high content of aromatics, comprising the following steps, in particular in such an order:
 a step of desulphurisation (HDS) and denitrification (HDN) of a feed, in particular LCO, is passed in presence of hydrogen over a catalyst, containing metals of the group VI B and VIII, leading to an effluent,   optionally a step of stripping of the effluent,   at least a subsequent step for dearomatization (HDA) in which at least a portion of the effluent, optionally stripped, is passed in presence of hydrogen over a catalyst comprising a combination of platinum and palladium supported on a carrier comprising silica-alumina dispersed in an alumina binder wherein the amount of alumina binder is 5-50 wt. % based on the total weight of the silica-alumina and alumina binder present in the carrier and wherein the silica-alumina comprises 5-50 wt. % of alumina based on the weight of the silica-alumina, and   recovering the final load obtained.   
     
     
         2 . Process according to  claim 1 , characterized in that in the HDA catalyst the alumina binder is present in an amount of 15-30 wt. %, based on the total weight of the silica-alumina and alumina binder present in the carrier. 
     
     
         3 . Process according to  claim 1 , characterized in that the carrier contains less than 20 wt. % of components other than silica-alumina and alumina, more particularly less than 10 wt. %, even more preferably less than 5 wt. % of other components and most preferably, the carrier consists essentially of silica-alumina dispersed in the alumina binder. 
     
     
         4 . Process according to  claim 1 , characterized in that in the HDA catalyst the silica-alumina contained in the carrier comprises 5-50 wt. % of alumina, based on the weight of the silica-alumina, preferably 10-40 wt. %, more preferably 15-30 wt. %, and more particularly the total amount of alumina present in the carrier preferably is between 10 and 60 wt. %, more preferably between 25 and 50 wt. %. 
     
     
         5 . Process according to  claim 1 , characterized in that the hydrogenation metals present in the HDA catalyst comprise, or consist essentially of, a combination of platinum and palladium. 
     
     
         6 . Process according to  claim 5 , characterized in that the total amount of platinum and palladium, calculated as metals on the total weight of the catalyst is between 0.1 and 3 wt. %, preferably between 0.2 and 2 wt. %, more preferably between 0.5 and 2 wt. %. 
     
     
         7 . Process according to  claim 5 , characterized in that platinum and palladium will each be present in an amount of 0.05-1.5 wt. %, preferably between 0.1 and 1 wt. %, more preferably between 0.25 and 1 wt. %. 
     
     
         8 . Process according to  claim 5 , characterized in that the platinum and the palladium have a dispersion higher than 20%, more preferably higher than 50%. 
     
     
         9 . Process according to  claim 1 , characterized in that the feed has an N content of more or equal to 100 ppm, specially more or equal to 150 ppm, and more particularly more or equal to 200 ppm. 
     
     
         10 . Process according to  claim 1 , characterized in that the feed has an S content of more or equal to 200 ppm, in particular more or equal to 250 ppm, and more particularly more or equal to 300 ppm. 
     
     
         11 . Process according to  claim 1 , characterized in that the feed has an aromatic content of more or equal to 50 wt. %, especially more or equal to 55 wt. %, in particular more or equal to 60 wt. %, and more particularly more or equal to 75 wt. %, even more particularly more or equal to 80 wt. %. 
     
     
         12 . Process according to  claim 1 , characterized in that the feed has a density at 15° C. in the range of 0.85 to 1 g/ml, in particular of 0.90 to 0.97 g/ml. 
     
     
         13 . Process according to  claim 1 , characterized in that the feed has a Cetane Index -CI- (ASTM D4737) of less or equal to 40, in particular less or equal to 35, and more particularly of less or equal to 30, and/or has a Cetane Number -CN- (ASTM D613-01) of less or equal to 35, in particular less or equal to 30, and more particularly of less or equal to 25. 
     
     
         14 . Process according to  claim 1 , characterized in that the catalyst used for decreasing the level of S and N content in the feed is of NiMo, CoMo or bulk (NiMoWO x ) type. 
     
     
         15 . Process according to  claim 1 , characterized in that the effluent obtained after HDS/N, stripping and HDA has a density at 15° C. in the range of 0.82 to 0.88. 
     
     
         16 . Process according to  claim 1 , characterized in that the final effluent has an S content of less or equal than 5 ppm, in particular of less or equal than 2 ppm, and more particularly of less or equal than 1 ppm and/or an N content of less or equal than 5 ppm, in particular of less or equal than 2 ppm, and more particularly of less or equal than 1 ppm. 
     
     
         17 . Process according to  claim 1 , characterized the aromatic content in the final effluent is less or equal to 10 wt. %, in particular less or equal to 5 wt. %, and more particularly less or equal to 2 wt. %, more particularly the content of monoaromatics is less or equal to 10 wt. %, in particular less or equal to 5 wt. %, and even more particularly the content of polyaromatics, for example di- or tri-aromatics, is less or equal than 5 wt. %, in particular less or equal to 2 wt. %. 
     
     
         18 . Process according to  claim 1 , characterized in that the Cetane Index of the final effluent is increased by 5 to 25 units, more particularly by 15 to 25 units compared with the Cetane Index of the starting feed, especially the Cetane Index of the final effluent is in the range of 30 to 45, and in particular in the range of 35 to 43. 
     
     
         19 . Process according to  claim 1 , characterized in that the Cetane Number of the final effluent is increased by 15 to 28 units, more particularly by 22 to 27 units compared to the Cetane Number of the starting feed, especially the Cetane Number of the final effluent is in the range of 35 to 50, and in particular in the range of 40 to 48. 
     
     
         20 . Use of a catalyst as defined in  claim 1  for increasing the cetane number, the cetane index, decreasing the S and/or N impurities and/or decreasing the density of a feed, for example an LCO or an LCO which had been treated with a catalyst for desulphurisation and/or denitrification. 
     
     
         21 . Process for preparing diesel comprising the step of mixing the final effluent obtained by a process as defined in  claim 1  with a composition having already characteristics of diesel, in particular the final effluent is incorporated in an amount of at least 50 wt. %, in particular at least 60 wt. %, and more particularly of at least 70 wt. % compared to the final weight of diesel obtained.