Process to prepare a lubricating base oil

Abstract

Process to prepare a lubricating base oil having a saturates content of greater than 90 wt % and a viscosity index of greater than 90 starting from a vacuum distillate feedstock by performing the following steps: (a) contacting the vacuum distillate feedstock with an extraction solvent selective for extracting aromatic compounds from the vacuum distillate, (b) mixing the extracted oil obtained in step (a) with a feed comprising of more than 50 wt % wax or comprising of more than 80 wt % of paraffins and having a pour point greater than 0° C., (c) hydrotreating the blend obtained in step (b), (d) catalytically dewaxing the hydrotreated oil obtained in step (c) to obtained the lubricating base oil and (e) contacting the dewaxed oil with an aromatics saturation catalyst.

1 . A process to prepare a lubricating base oil having a saturates content of greater than 90 wt % and a viscosity index of greater than 90 starting from a vacuum distillate feedstock by performing the following steps: 
 (a) contacting the vacuum distillate feedstock with an extraction solvent selective for extracting aromatic compounds from the vacuum distillate feedstock,    (b) mixing the extracted oil obtained in step (a) with a feed comprising of more than 50 wt % wax or comprising of more than 80 wt % of paraffins and having a pour point greater than 0° C.,    (c) hydrotreating the blend obtained in step (b),    (d) catalytically dewaxing the hydrotreated oil obtained in step (c) to obtained the lubricating base oil and    (e) contacting the dewaxed oil obtained in step (d) with an aromatics saturation catalyst to yield the lubricating base oil.    
     
     
         2 . A process according to  claim 1 , wherein the feed comprising of more than 50 wt % of wax in step (b) is a slack wax.  
     
     
         3 . A process according to  claim 1 , wherein the feed comprising more than 80 wt % paraffins and a pour point of greater than 0° C. in step (b) is a partly isomerised Fischer-Tropsch wax having a wax content of between 10 and 80 wt %.  
     
     
         4 . A process according to  claim 3 , wherein the partly isomerised Fischer-Tropsch wax has a wax content of between 20 and 60 wt %.  
     
     
         5 . A process according to  claim 4 , wherein the blend obtained in step (b) comprises between 5 and 50 wt % of the paraffinic and/or waxy feed.  
     
     
         6 . A process according to  claim 5 , wherein the blend obtained in step (b) comprises between 5 and 30 wt % of the paraffinic and/or waxy feed.  
     
     
         7 . A process according to  claim 6 , wherein step (c) is performed in the presence of a hydrotreating catalyst comprising one of the following combinations of metals selected from the group consisting of nickel/molybdenum, cobalt/molybdenum and nickel/tungsten.  
     
     
         8 . A process according to  claim 1 , wherein step (d) is performed in the presence of a dewaxing catalyst comprising a binder, a Group VIII metal, a molecular sieve selected from the group consisting of ZSM-5, ZSM-12, ZSM-22, ZSM-23, SSZ-32, ZSM-35, ZSM-48 and SAPO-11.  
     
     
         9 . A process according to  claim 8 , wherein the molecular sieve is selected from the group consisting of ZSM-12, ZSM-23, ZSM-22 and SSZ-32.  
     
     
         10 . A process according to  claim 9 , wherein the Group VIII metal is platinum.  
     
     
         11 . A process according to  claim 10 , wherein the content of molecular sieve in the dewaxing catalyst is between 5 and 40 wt %.  
     
     
         12 . A process according to  claim 11 , wherein the average crystal size of the molecular sieve is smaller than 0.5 μm and more preferably smaller than 0.1 μm as determined by the X-ray diffraction (XRD) line broadening technique using the high intensity peak at about 20.9 2-theta in the XRD diffraction pattern.  
     
     
         13 . A process according to  claim 12 , wherein the lubricating base oil as obtained have a pour point of below −18° C. and more preferably below −27° C.  
     
     
         14 . A process according to  claim 13 , wherein the lubricating base oil as obtained has a kinematic viscosity at 100° C. in the range of from 2 and 15 cSt.  
     
     
         15 . A process according to  claim 14 , wherein the lubricating base oil as obtained has a viscosity index in the range of from 100 and 135.  
     
     
         16 . A process according to  claim 15 , wherein the lubricating base oil as obtained has a saturates content of above 95 wt %.  
     
     
         17 . A process according to  claim 16 , wherein the lubricating base oil as obtained has a sulphur content of below 50 ppmw.