Patent ID: 7473347
Filing Date: 2009-01-06
Classification: C10G

Abstract:
1. A process to prepare two or more base oil grades, which base oil grades having different kinematic viscosities at 100° C. than a waxy paraffinic Fischer-Tropsch product having a content of non-cyclic iso-paraffins of more than 70 wt %, the process comprising: (a) obtaining from the waxy paraffinic Fischer-Tropsch product a distillate fraction having a viscosity corresponding to one of the desired base oil grades; (b) performing a catalytic dewaxing step using the distillate fraction obtained in step (a) as feed to produce a dewaxed product comprising lower boiling compounds; (c) separating the lower boiling compounds from the dewaxed product obtained in step(b) in order to obtain the base oil grade; and (d) repeating steps (a)–(c) for each base oil grade, wherein the base oil having a kinematic viscosity at 100° C. of between 4.5 cSt and 6 cSt is prepared and wherein the kinematic viscosity at 100° C. of the distillate fraction as obtained in step (a) is between 0.8*P and 1.2*P, wherein P=vK@100 p−ΔPP/200, in which equation vK@100 p is the kinematic viscosity at 100° C. of the base oil product as obtained in step (c) and ΔPP is the absolute difference in pour point of said fraction obtained in step (a) and said product obtained in step (c) in degrees Celsius.