High viscosity base stock compositions

Abstract

Methods are provided for producing Group I base stocks having high viscosity and also having one or more properties indicative of a high quality base stock. The resulting Group I base stocks can have a viscosity at 100° C. and/or a viscosity at 40° C. that is greater than the corresponding viscosity for a conventional Group I bright stock formed by solvent processing. Additionally, the resulting Group I base stocks can have one or more properties that are indicative of a high quality base stock.

1 - 13 . (canceled) 
     
     
         14 . A method of forming a base stock composition, comprising:
 introducing a feedstock having a viscosity index of 50 to 120, a kinematic viscosity at 100° C. of 12 cSt or less, and at least one of a sulfur content greater than 0.03 wt % and an aromatics content greater than 10 wt %, into a coupling reaction stage under effective coupling conditions to form a coupled effluent; and   fractionating at least a portion of the coupled effluent to form at least a first product fraction having a viscosity index of at least 50, a polydispersity (M w /M n ) of at least 1.4, a kinematic viscosity at 100° C. of at least 35 cSt, a kinematic viscosity at 40° C. of at least 600 cSt, and a pour point of 0° C. or less.   
     
     
         15 . The method of  claim 14 , wherein the effective coupling conditions comprise exposing the feedstock to at least 20 wt % dialkyl peroxide relative to a combined weight of feedstock and peroxide. 
     
     
         16 . The method of  claim 14 , wherein the effective coupling conditions comprise acid-catalyzed coupling conditions. 
     
     
         17 . The method of  claim 14 , further comprising exposing at least a portion of the coupled effluent to a catalyst under effective catalytic processing conditions to form a catalytically processed effluent, wherein fractionating at least a portion of the coupled effluent comprises fractionating at least a portion of the catalytically processed effluent. 
     
     
         18 . The method of  claim 17 , wherein the effective catalytic processing conditions comprises at least one of hydrotreatment conditions, catalytic dewaxing conditions, and hydrofinishing conditions. 
     
     
         19 . The method of  claim 14 , wherein the polydispersity is at least 1.7. 
     
     
         20 . A method of forming a base stock composition, comprising:
 introducing a feedstock having a viscosity index of 50 to 120, a kinematic viscosity at 100° C. of 12 cSt or less, and at least one of a sulfur content greater than 0.03 wt % and an aromatics content greater than 10 wt %, into a coupling reaction stage under effective coupling conditions to form a coupled effluent;   fractionating at least a portion of the coupled effluent to form at least a first coupled effluent fraction; and   exposing at least a portion of the first coupled effluent fraction to a catalyst under effective catalytic processing conditions to form the first product fraction having a viscosity index of at least 50, a polydispersity (M w /M n ) of at least 1.4, a kinematic viscosity at 100° C. of at least 35 cSt, a kinematic viscosity at 40° C. of at least 600 cSt, and a pour point of 0° C. or less.