Process to prepare residual base oil

Abstract

The present invention provides a process to prepare a residual base oil, which process at least comprises the following steps: (a) providing a mineral bright stock waxy raffinate; (b) combining the mineral bright stock waxy raffinate provided in step (a) with a catalytically dewaxed residual Fischer-Tropsch derived base oil to obtain a mixture; and (c) solvent dewaxing the mixture obtained in (b) to obtain a residual base oil, wherein the weight ratio of the mineral bright stock waxy raffinate to the catalytically dewaxed residual Fischer-Tropsch derived base oil in step (b) is in the range of from 75:25 to 35:65. In another aspect the present invention provides a residual base oil obtainable by the process.

1 . A process to prepare a residual base oil, the process comprising the steps of:
 (a) providing a mineral bright stock waxy raffinate;   (b) combining the mineral bright stock waxy raffinate provided in step (a) with a catalytically dewaxed residual Fischer-Tropsch derived base oil to obtain a mixture; and   (c) solvent dewaxing the mixture obtained in (b) to obtain a residual base oil, wherein the weight ratio of the mineral bright stock waxy raffinate to the catalytically dewaxed residual Fischer-Trospch derived base oil in step (b) is in the range of from 75:25 to 35:65.   
     
     
         2 . The process according to  claim 1 , wherein the mineral bright stock waxy raffinate is prepared using the following steps:
 (aa) providing a mineral derived vacuum residue;   (bb) performing a de-asphalting step on the mineral derived vacuum residue to obtain a de-asphalted oil; and   (cc) solvent extracting the de-asphalted oil to obtain a residual aromatic extract and the mineral bright stock waxy raffinate.   
     
     
         3 . The process according to  claim 1 , wherein the mineral bright stock waxy raffinate in step (a) has a kinematic viscosity at 100° C. from 20 to 50 mm 2 /s, preferably from 30 to 50 mm 2 /s, more preferably from 30 to 40 mm 2 /s. 
     
     
         4 . The process according to  claim 1 , wherein the catalytically dewaxed residual Fischer-Tropsch base oil in step (b) has a kinematic viscosity at 100° C. from 12 to 50 mm 2 /s. 
     
     
         5 . The process according to  claim 1 , wherein the catalytically dewaxed residual Fischer-Tropsch derived base oil in step (b) has a pour point of below 0° C. 
     
     
         6 . The process according to  claim 1 , wherein the catalytically dewaxed residual Fischer-Tropsch derived base oil in step (b) has a cloud point of above 15° C. 
     
     
         7 . The process according to  claim 1 , wherein the mixture obtained in step (b) comprises from 10 to 80 wt. %. 
     
     
         8 . A residual base oil obtainable by the process according to  claim 1 . 
     
     
         9 . The residual base oil according to  claim 8 , having a kinematic viscosity at 100° C. from 12 to 50 mm 2 /s. 
     
     
         10 . The residual base oil according to  claim 8 , having a viscosity index of greater than 95. 
     
     
         11 . The residual base oil according to  claim 8 , having a pour point of below −5° C. 
     
     
         12 . The residual base oil according to  claim 8 , having a cloud point of below −10° C.