Process for reducing the cloud point of a base oil

Abstract

The invention relates to a process for reducing the cloud point of a base oil feed having a kinematic viscosity at 100° C. of greater than 10 cSt by separating the molecules inferring the high cloud point from the base oil by (a) depositing said molecules on one side of a cooled surface, (b) obtaining a base oil having a reduced cloud point and (c) melting the deposited molecules and separating the melted molecules from the surface and reusing said surface to perform step (a).

1 . A process for reducing the cloud point of a base oil feed having a kinematic viscosity at 100° C. of greater than 10 cSt by separating the molecules inferring the high cloud point from the base oil by
 (a) depositing said molecules on one side of a cooled surface;   (b) obtaining a base oil having a reduced cloud point; and   (c) melting the deposited molecules and separating the melted molecules from the surface and reusing said surface to perform step (a).   
   
   
       2 . The process according to  claim 1 , wherein the temperature of the surface is between the cloud point and the pour point of the base oil feed. 
   
   
       3 . The process according to  claim 2 , wherein the surface is cooled at the other side of the surface by a cooling medium. 
   
   
       4 . The process according to  claim 1 , wherein the surface comprises a substantially vertical oriented tube or arrangement of tubes at which inner side of the tube or tubes the base oil feed is allowed to flow and wherein outside of the tube a cooling medium flows. 
   
   
       5 . The process according to  claim 1 , wherein the base oil has a cloud point greater than 20° C., a saturates content of greater than 97 wt %, a kinematic viscosity at 100° C. of greater than 12 cSt, a sulphur content of less than 50 ppm and a viscosity index of greater than 130. 
   
   
       6 . The process according to  claim 1 , wherein the base oil feed is prepared from carbon monoxide and hydrogen by
 (i) contacting carbon monoxide and hydrogen with a hydrocarbon synthesis catalyst at elevated temperature and pressure to prepare a substantially paraffinic hydrocarbon wax;   (ii) subjecting the paraffinic wax to a pour point reducing treatment by means of catalytic dewaxing/isomerisation; and   (iii) isolating by means of distillation a distillation bottoms fraction as the heavy base oil.   
   
   
       7 . The process according to  claim 6 , further comprising performing a hydrocracking/hydroisomerisation step on the paraffinic wax prior to the pour point reducing treatment.