Upgrading of used lubricating oil to group ii/iii base stock at high yield

Abstract

Methods relate to processing a used lubricating oil, to form high quality Group II base stocks and Group III base stocks from pre-processed used lubricating oil.

1 . A method for producing base stocks comprising:
 introducing a stream comprising pre-processed used lubricating oil into a hydrotreatment unit comprising a demetallization section and a hydrotreatment section;   contacting the pre-processed used lubricating oil with a demetallization catalyst in the demetallization section;   contacting an effluent from the demetallization section with a hydrotreatment catalyst in the hydrotreatment section and hydrotreating the effluent to form a hydrotreated oil;   introducing the hydrotreated oil into a first separation unit and separating a light end fraction from the hydrotreated oil;   introducing the hydrotreated oil into a hydrofinishing unit comprising a hydrofinishing section;   contacting the hydrotreated oil with a hydrofinishing catalyst in the hydrofinishing section to hydrofinish at least a portion of the hydrotreated oil to form a hydrofinished oil; and   introducing the hydrofinished oil into a second separation unit and separating a base stock fraction from the hydrofinished oil.   
     
     
         2 . The method of  claim 1  wherein hydrotreating at least the portion of the pre-processed used lubricating oil further forms the light end fraction comprising at least one component selected from the group consisting of hydrogen sulfide, ammonia, water, and combinations thereof. 
     
     
         3 . The method of  claim 1  wherein the light end fraction comprises at least one species selected form the group consisting of hydrogen sulfide, ammonia, water, light hydrocarbons with boiling points less than 370° C., and combinations thereof. 
     
     
         4 . The method of  claim 3  wherein the light hydrocarbons comprise fuel range light ends and wherein the method further comprises separating at least a portion of the fuel range light ends in the first separation unit to form a fuel stream. 
     
     
         5 . The method of  claim 1  wherein hydrofinishing the portion of the hydrotreated oil further forms a second light end fraction having a boiling point at a point in a range of about 30° C. to about 370° C. 
     
     
         6 . 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. 
     
     
         7 . 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 D2270-10. 
     
     
         8 . The method of  claim 1  wherein the base stock fraction has a sulfur content less than 5 ppm as measured according to ASTM D2622. 
     
     
         9 . The method of  claim 1  wherein the base stock fraction has a saturates content of greater than 95 wt. % as measured according to ASTM D7419-18. 
     
     
         10 . The method of  claim 1  wherein the base stock fraction has a metal content less than 10 ppm as measured according to ASTM D5185-18. 
     
     
         11 . The method of  claim 1  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 hydrotreatment 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. 
     
     
         12 . The method of  claim 1  wherein the pre-processed used lubricating oil has a sulfur content of less than 500 ppm as measured according to ASTM D2622. 
     
     
         13 . The method of  claim 1  further comprising blending the base stock fraction with a second base stock to form 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. % as measured according to ASTM D2622, and a viscosity index in a range of about 80 to about 120 as measured according to ASTM D2270-10. 
     
     
         14 . A method for producing base stocks comprising:
 introducing a stream comprising pre-processed used lubricating oil into a hydrotreatment unit comprising a demetallization section and a hydrotreatment section;   contacting the pre-processed used lubricating oil with a demetallization catalyst in the demetallization section and demetallizing at least a portion of the pre-processed used lubricating oil;   contacting the pre-processed used lubricating oil with a hydrotreatment catalyst in the hydrotreatment section and hydrotreating at least a portion of the pre-processed used lubricating oil to form a hydrotreated oil;   introducing the hydrotreated oil into a hydrodewaxing unit comprising a hydrodewaxing section and contacting the hydrotreated oil with a dewaxing catalyst in the hydrodewaxing section to form a dewaxed oil;   introducing the dewaxed oil into a hydrofinishing unit comprising a hydrofinishing section and hydrofinishing the dewaxed oil to form a hydrofinished lubricant boiling range product; and   introducing the hydrofinished lubricant boiling range product into a separation unit and separating a Group II/III base stock fraction.   
     
     
         15 . The method of  claim 14  wherein the base stock fraction has a viscosity index of about 80 to about 120 as measured according to ASTM D2270-10. 
     
     
         16 . The method of  claim 14  wherein the Group III 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 14  wherein the base stock fraction has a saturates content of greater than 95 wt. % as measured according to ASTM D7419-18. 
     
     
         18 . The method of  claim 14  wherein the base stock fraction has a sulfur content of less than 0.03 wt. % as measured according to ASTM D2622. 
     
     
         19 . The method of  claim 14  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 hydrotreatment 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. 
     
     
         20 . The method of  claim 14  wherein the base stock fraction has a sulfur content less than 5 ppm as measured according to ASTM D2622. 
     
     
         21 . The method of  claim 14  wherein hydrotreating at least the portion of the pre-processed used lubricating oil further forms a light end fraction comprising at least one component selected from the group consisting of hydrogen sulfide, ammonia, water, light hydrocarbons with boiling points less than 370° C., and combinations thereof. 
     
     
         22 . The method of  claim 21  wherein the light hydrocarbons comprise fuel range light ends and wherein the method further comprises separating at least a portion of the fuel range light ends in the separation unit to form a fuel stream.