Method for preparing a naphthenic brightstock from a naphthenic feedstock based on naphthenic deasphalted oil

Abstract

A method of preparing a naphthenic brightstock from a naphthenic feedstock based on naphthenic deasphalted oil (DAO) is disclosed. The method includes a hydroprocessing step B, which step is sub-divided into three separate steps; B1 low pressure catalytic hydroprocessing, B2 high pressure catalytic hydroprocessing, and, B3 catalytic dewaxing. The naphthenic brightstock exhibits a reduced viscosity and increased viscosity index as compared to the naphthenic DAO feedstock, and the method allows for a broader range of naphthenic DAO feedstocks to be used for preparing the naphthenic brightstock.

1 . A method of preparing a naphthenic brightstock comprising the following steps:
 A) providing a naphthenic feedstock based on naphthenic deasphalted oil (DAO):   B) hydroprocessing of the naphthenic feedstock based on naphthenic deasphalted oil to obtain a hydroprocessed product; and,   C) fractionation of the hydroprocessed product, so as to obtain a naphthenic brightstock,   wherein the viscosity of the naphthenic feedstock in step (A) is within the range of 45-65 mm 2 /s at 100° C.,   wherein the hydroprocessing step (B) comprises the following three separate steps:
 B1) low pressure catalytic hydroprocessing of the naphthenic feedstock based on naphthenic deasphalted oil, thereby obtaining a low pressure catalytically hydroprocessed liquid product, wherein the low pressure catalytic hydroprocessing step (B1) is carried out within a hydrogen partial pressure range of 5.0-7.0 MPa: 
 B2) high pressure catalytic hydroprocessing of the low pressure catalytically hydroprocessed liquid product leaving from the low pressure catalytic hydroprocessing step (B1), thereby obtaining a high pressure catalytically hydroprocessed product, wherein the high pressure catalytic hydroprocessing step (B2) is carried out within a hydrogen partial pressure range of 13-15 MPa; and, 
 B3) catalytic dewaxing of the high pressure catalytically hydroprocessed product leaving from the high pressure catalytic hydroprocessing step (B2), thereby obtaining a catalytically dewaxed product which constitutes the hydroprocessed product resulting from step (B). 
   
     
     
         2 . The method of  claim 1 , additionally comprising a step of solvent deasphalting using a solvent selected from C2-C8 alkanes, furfural, and N-methyl-2-pyrrolidone, and preferably propane, thereby obtaining the naphthenic DAO of the naphthenic feedstock in step (A). 
     
     
         3 . The method of  claim 1 , wherein the viscosity of the feedstock in step (A) is within the range of 50-60 mm 2 /s at 100° C. 
     
     
         4 . The method as in  any one of the preceding claims , wherein the low pressure catalytic hydroprocessing step (B1) is carried out at one or more conditions selected from the following group of conditions: a temperature within the range of 340-375° C.: an LHSV within the range of 0.1-0.4 h −1 ; and, a hydrogen to oil ratio within the range of 300-700 Nm 3 /m 3 , and preferably at a combination of all conditions. 
     
     
         5 . The method as in  any one of the preceding claims , wherein the high pressure catalytic hydroprocessing step (B2) is carried out at one or more conditions selected from the following group of conditions: a temperature within the range of 370-420° C.: an LHSV within the range of 0.7-1.4 h-1; and, a hydrogen to oil ratio within the range of 700-1400 Nm 3 /m 3 , and preferably at a combination of all conditions. 
     
     
         6 . The method as in  any one of the preceding claims , wherein the catalytic dewaxing step (B3) is carried out at one or more conditions selected from the following group of conditions: a temperature within the range of 240-370° C.: a hydrogen partial pressure within the range of 2.0-15 MPa, preferably 2.0-7.5 MPa or 13-15 MPa: an LHSV within the range of 0.5-2.0 h-1; and, a hydrogen to oil ratio within the range of 200-1400 Nm 3 /m 3 , preferably 700-1400 Nm 3 /m 3  or 200-500 Nm 3 /m 3 , and preferably at a combination of all conditions. 
     
     
         7 . The method as in  any one of the preceding claims , wherein the hydroprocessing step (B) additionally comprises the following fourth step:
 B4) catalytic hydrofinishing of the catalytically dewaxed product leaving from the catalytic dewaxing step (B3), thereby obtaining a catalytic hydrofinished product which constitutes the hydroprocessed product resulting from step (B).   
     
     
         8 . The method of  claim 7 , wherein the catalytic hydrofinishing step (B4) is carried out at one or more conditions selected from the following group of conditions: a temperature within the range of 240-370° C.; a hydrogen partial pressure within the range of 2.0-7.5 MPa; a hydrogen to oil ratio within the range of 200-500 Nm 3 /m 3 ; and, an LHSV within the range of 3-20 h-1, and preferably at a combination of all conditions. 
     
     
         9 . The method of  claim 7 , wherein the catalytic dewaxing step (B3) and the catalytic hydrofinishing step (B4) both are carried out within one and the same reactor. 
     
     
         10 . The method as in  any one of the preceding claims , wherein, in steps (B1), (B2), and (B3), and, when included, also in (B4), only base metal catalysts are used.