Coprocessing of used lubricating oil to increase group ii/iii base stock production

Abstract

Methods of processing a pre-processed used lubricating oil to methods to form high quality Group II base stock, Group II+ base stock, and Group III base stock include co-processing vacuum gas oil (VGO) with pre-processed used lubricating oil.

1 . A method comprising:
 introducing a feed stream comprising pre-processed used lubricating oil and vacuum gas oil into a solvent extraction unit;   contacting the feed stream with a solvent in the solvent extraction unit and forming a raffinate stream comprising lubricant boiling range hydrocarbons and sulfur;   introducing the raffinate stream into a hydrotreatment section;   contacting the raffinate stream with a hydrotreatment catalyst and hydrogen in the hydrotreatment section and forming a hydro-converted product;   introducing the hydro-converted product into a stripper to form a stripped effluent;   introducing the stripped effluent into a catalytic dewaxing section;   contacting the hydro-converted product with a dewaxing catalyst and hydrogen in the catalytic dewaxing section at catalytic dewaxing conditions effective to dewax at least a portion of the hydro-converted product to form a dewaxed effluent;   introducing the dewaxed effluent into a hydrofinishing section;   contacting the dewaxed effluent with a hydrofinishing catalyst and hydrogen in the hydrofinishing section at hydrofinishing conditions to hydrofinish at least a portion of the dewaxed effluent to form a hydrofinished effluent; and   introducing the hydrofinished effluent into a separation unit and separating at least a portion of the lubricant boiling range hydrocarbons to form a base stock fraction.   
     
     
         2 . The method of  claim 1  wherein the feed stream comprises about 1 vol. % to about 50 vol. % of the pre-processed used lubricating oil. 
     
     
         3 . The method of  claim 1  wherein the pre-processed used lubricating oil is processed to reduce at least one contaminant selected from an additive, water, insoluble particles, and combinations thereof. 
     
     
         4 . The method of  claim 3  wherein used lubricating oil is subjected to at least one pre-processing step prior to the stream being introduced into the solvent extraction unit, wherein the pre-processing step is selected from the group consisting of filtering, stripping, chemical addition, separation, solvent extraction, vacuum distillation, and combinations thereof. 
     
     
         5 . The method of  claim 1  wherein the lubricant boiling range hydrocarbons have a boiling point in a range of about 343° C. to about 566° C. 
     
     
         6 . The method of  claim 1  wherein the hydrofinished effluent further comprises fuel range hydrocarbons selected from the group consisting of naphtha boiling range hydrocarbons, distillate fuel boiling range hydrocarbons, and combinations thereof, and further comprising separating at least a portion of the fuel range hydrocarbons to form a fuel stream. 
     
     
         7 . The method of  claim 1  wherein the base stock fraction has a kinematic viscosity at 100° C. of about 4 to about 6 cSt as measured according to ASTM D 445-01. 
     
     
         8 . The method of  claim 1  wherein the base stock fraction has a viscosity index of about 115 to about 125 as measured according to ASTM D2270-93. 
     
     
         9 . The method of  claim 1  wherein the base stock fraction has a sulfur content less than 5 ppm as measured according to ASTM D2622. 
     
     
         10 . The method of  claim 1  wherein the base stock fraction has a saturates content of greater than 98 wt. % as measured according to ASTM D7419-18. 
     
     
         11 . The method of  claim 1  wherein the base stock fraction is a Group II base stock and wherein the base stock fraction has a saturates content of greater than 90 wt. %, a sulfur content of less than 0.03 wt. %, and a viscosity index in a range of about 80 to about 120. 
     
     
         12 . The method of  claim 1  wherein the base stock fraction is essentially free of metal contaminants, having metals below detection limits as measured according to ASTM D5185. 
     
     
         13 . A method comprising:
 introducing a feed stream comprising pre-processed used lubricating oil and vacuum gas oil into a solvent extraction unit, wherein the feed stream comprises about 5 vol. % to about 15 vol. % pre-processed used lubricating oil, and contacting the feed stream with a solvent to form a raffinate stream comprising lubricant boiling range hydrocarbons and sulfur;   contacting the raffinate stream with a hydrotreatment catalyst and hydrogen at hydrotreatment conditions effective to hydrotreat at least a portion of the sulfur to H 2 S and forming a hydro-converted product;   introducing the hydro-converted product into a stripper to form a stripped effluent;   contacting the stripped effluent with a dewaxing catalyst and hydrogen at catalytic dewaxing conditions effective to dewax at least a portion of the stripped effluent to form a dewaxed effluent;   contacting the dewaxed effluent with a hydrofinishing catalyst and hydrogen at hydrofinishing conditions to hydrofinish at least a portion of the dewaxed effluent to form a hydrofinished effluent; and   separating lubricant boiling range hydrocarbons from the hydrofinished effluent to form a base stock fraction wherein the lubricant boiling range hydrocarbons have a boiling point in a range of about 343° C. to about 566° C.   
     
     
         14 . The method of  claim 13  wherein the pre-processed used lubricating oil is subjected to at least one pre-processing step prior to introducing the pre-processed used lubricating oil into the solvent extraction unit, wherein the pre-processing step is selected from the group consisting of filtering, stripping, chemical addition, separation, solvent extraction, vacuum distillation, and combinations thereof. 
     
     
         15 . The method of  claim 13  wherein the feed stream comprises about 1 vol. % to about 50 vol. % of the pre-processed used lubricating oil. 
     
     
         16 . The method of  claim 14  wherein the base stock fraction has a kinematic viscosity at 100° C. of about 4 to about 6 cSt as measured according to ASTM D 445-01. 
     
     
         17 . The method of  claim 15  wherein the base stock fraction has a viscosity index of about 115 to about 125 as measured according to ASTM D2270-93. 
     
     
         18 . The method of  claim 14  wherein the base stock fraction has a sulfur content less than 5 ppm as measured according to ASTM D2622. 
     
     
         19 . The method of  claim 14  wherein the base stock fraction has a saturates content of greater than 98 wt. % as measured according to ASTM D7419-18. 
     
     
         20 . The method of  claim 14  wherein the base stock fraction is a Group II base stock and wherein the base stock fraction has a saturates content of greater than 90 wt. %, a sulfur content of less than 0.03 wt. %, and a viscosity index in a range of about 80 to about 120. 
     
     
         21 . The method of  claim 14  wherein the base stock fraction is a Group III base stock and wherein the base stock fraction has a saturates content of greater than 90 wt. %, a sulfur content of less than 0.03 wt. %, and a viscosity index greater than 120. 
     
     
         22 . The method of  claim 14  wherein the base stock fraction is essentially free of metal contaminants, having metals below detection limits as measured according to ASTM D5185.