Process for improving base oil yields

Abstract

An improved process for making a base oil and for improving base oil yields by combining an atmospheric resid feedstock with a base oil feedstock and forming a base oil product via hydroprocessing. The process generally involves subjecting a base oil feedstream comprising the atmospheric resid to hydrocracking and dewaxing steps, and optionally to hydrofinishing, to produce a light and heavy grade base oil product. A process is also disclosed for making a base oil having a viscosity index of 120 or greater from a base oil feedstock having a viscosity index of about 100 or greater that includes a narrow cut-point range vacuum gas oil. The invention is useful to make Group II and/or Group III/III+ base oils, and, in particular, to increase the yield of a heavy base oil product relative to a light base oil product produced in the process.

1 . A process for making a base oil, comprising
 combining an atmospheric resid feedstock and a base oil feedstock to form a base oil feedstream;   contacting the base oil feedstream with a hydrocracking catalyst under hydrocracking conditions to form a hydrocracked product;   separating the hydrocracked product into a gaseous fraction and a liquid fraction;   contacting the liquid fraction with a dewaxing catalyst under hydroisomerization conditions, to produce a dewaxed product; and   optionally, contacting the dewaxed product with a hydrofinishing catalyst under hydrofinishing conditions to produce a hydrofinished dewaxed product.   
     
     
         2 . The process of  claim 1 , wherein the atmospheric resid feedstock meets one or more of the following conditions:
 API gravity in the range of 20-60 or 20-45 or 25-45, or at least 20, or at least 22, or, optionally, greater than the API of the base oil feedstock;   VI in the range of 50-200 or 70-190 or 90-180, or at least 80, or, optionally, greater than the VI of the base oil feedstock;   viscosity at 100° C. in the range of 3-30 cSt or 3-25 cSt or 3-20 cSt, or at least 3 cSt, or at least 4 cSt;   viscosity at 70° C. in the range of 5-25 cSt or 5-20 cSt or 5-15 cSt, or at least 5 cSt, or at least 6 cSt;   hot C 7  asphaltene content in the range of 0.01-0.3 wt. % or 0.01-0.2 wt. % or 0.02-0.15 wt. %, or less than 0.3 wt. %, or less than 0.2 wt. %;   wax content in the range of 5-40 wt. % or 5-30 wt. % or 10-25 wt. %, or at least 5 wt. % or at least 10 wt. %, or at least 15 wt. %, or, optionally, greater than the wax content of the base oil feedstock;   nitrogen content of less than 2500 ppm or less than 2000 ppm or less than 1500 ppm or less than 1000 ppm or less than 500 ppm or less than 200 ppm or less than 100 ppm;   sulfur content of less than 8000 ppm or less than 6000 ppm or less than 4000 ppm or less than 2000 ppm or less than 1000 ppm or less than 500 ppm or less than 200 ppm, or in the range of 100-8000 ppm or 100-6000 ppm or 100-4000 ppm or 100-2000 ppm or 100-1000 ppm or 100-500 ppm or 100-200 ppm; and/or   1050+° F. content in the range of 5-50 wt. % or 5-40 wt. % or 8-40 wt. %, or, optionally, greater than the 1050+° F. content of the base oil feedstock.   
     
     
         3 . The process of  claim 1 , wherein the base oil feedstock meets one or more of the following conditions:
 API gravity in the range of 15-40 or 15-30 or 15-25, or at least 15, or at least 17, optionally, less than the atmospheric resid feedstock;   VI in the range of 30-90 or 40-90 or 50-90 or 50-80, optionally, less than the VI of the atmospheric resid feedstock;   viscosity at 100° C. in the range of 3-30 cSt or 3-25 cSt or 3-20 cSt, or at least 3 cSt, or at least 4 cSt;   viscosity at 70° C. in the range of 5-25 cSt or 5-20 cSt or 5-15 cSt, or at least 5 cSt, or at least 6 cSt;   hot C 7  asphaltene content in the range of 0.01-0.3 wt. % or 0.01-0.2 wt. % or 0.02-0.15 wt. %, or less than 0.3 wt. %, or less than 0.2 wt. %;   wax content in the range of 5-40 wt. % or 5-30 wt. % or 10-25 wt. %, or at least 5 wt. % or at least 10 wt. %, or at least 15 wt. %, or, optionally, greater than the wax content of the base oil feedstock;   nitrogen content of less than 2500 ppm or less than 2000 ppm or less than 1500 ppm or less than 1000 ppm or less than 500 ppm or less than 200 ppm or less than 100 ppm;   sulfur content of less than 8000 ppm or less than 6000 ppm or less than 4000 ppm or less than 2000 ppm or less than 1000 ppm or less than 500 ppm or less than 200 ppm, or in the range of 100-8000 ppm or 100-6000 ppm or 100-4000 ppm or 100-2000 ppm or 100-1000 ppm or 100-500 ppm or 100-200 ppm; and/or   1050+° F. content in the range of 5-50 wt. % or 5-40 wt. % or 8-40 wt. %, or, optionally, greater than the 1050+° F. content of the base oil feedstock.   
     
     
         4 . The process of  claim 1 , wherein the base oil feedstream comprises 10-60 wt. % atmospheric resid feedstock and 40-90 wt. % base oil feedstock, or 10-40 wt. % atmospheric resid feedstock and 60-90 wt. % base oil feedstock, or 10-30 wt. % atmospheric resid feedstock and 70-90 wt. % base oil feedstock, or 30-60 wt. % atmospheric resid feedstock and 40-70 wt. % base oil feedstock, or 40-60 wt. % atmospheric resid feedstock and 40-60 wt. % base oil feedstock. 
     
     
         5 . The process of  claim 1 , wherein the base oil feedstream does not contain an added whole crude oil feedstock, or wherein the base oil feedstream does not contain a vacuum residue feedstock, or wherein the base oil feedstream does not contain a deasphalted oil, or wherein the base oil feedstream contains only atmospheric resid feedstock and base oil feedstock. 
     
     
         6 . The process of  claim 1 , wherein the process does not include recycle of a liquid feedstock as part of the base oil feedstream or as either or both of the atmospheric resid feedstock and the base oil feedstock. 
     
     
         7 . The process of  claim 1 , wherein the base oil feedstock comprises vacuum gas oil or is vacuum gas oil, or consists essentially of vacuum gas oil, or consists of vacuum gas oil. 
     
     
         8 . The process of  claim 7 , wherein the vacuum gas oil is a heavy vacuum gas oil obtained from vacuum gas oil that is cut into a light fraction and a heavy fraction, with the heavy fraction having a cut point temperature range of about 950-1050° F. 
     
     
         9 . The process of  claim 1 , wherein the dewaxed product and/or the hydrofinished dewaxed product is obtained as a light base oil product and a heavy base oil product. 
     
     
         10 . The process of  claim 9 , wherein the light base oil product has a nominal viscosity in the range of 4-8 cSt or 5-7 cSt at 100° C. and/or the heavy base oil product has a nominal viscosity in the range of 10-14 cSt or 11-13 cSt at 100° C. 
     
     
         11 . The process of  claim 9 , wherein the yield of the heavy base oil product relative to the light base oil product is increased by at least about 2 Lvol. % or at least about 5 Lvol % compared with the same process that does not include the atmospheric resid feedstock in the base oil feedstream. 
     
     
         12 . The process of  claim 9 , wherein the total waxy base oil yield is increased by at least about 2 Lvol. % or at least about 5 Lvol % compared with the same process that does not include the atmospheric resid feedstock in the base oil feedstream. 
     
     
         13 . The process  claim 1 , wherein the dewaxed product is further separated into at least a lighter product having a nominal viscosity of 6 cSt at 100° C., or at least a heavier product having a nominal viscosity of 12 cSt at 100° C., or a combination thereof. 
     
     
         14 . A method for modifying a base oil process, wherein the base oil process comprises subjecting a base oil feedstream to hydrocracking and dewaxing steps to form a dewaxed product comprising a light product and a heavy product; the method comprising,
 combining an atmospheric resid feedstock with a base oil feedstock to form the base oil feedstream; and   subjecting the base oil feedstream comprising the atmospheric resid feedstock to the hydrocracking and dewaxing steps of the base oil process;   wherein the modified base oil process comprises:   combining an atmospheric resid feedstock and a base oil feedstock to form a base oil feedstream;   contacting the base oil feedstream with a hydrocracking catalyst under hydrocracking conditions to form a hydrocracked product;   separating the hydrocracked product into at least a gaseous fraction and a liquid fraction;   contacting the liquid fraction with a dewaxing catalyst under hydroisomerization conditions, to produce a dewaxed product; and   optionally, contacting the dewaxed product with a hydrofinishing catalyst under hydrofinishing conditions to produce a hydrofinished dewaxed product.   
     
     
         15 . A process for making a base oil, comprising
 contacting a base oil feedstock having a viscosity index of about 100 or greater with a hydrocracking catalyst under hydrocracking conditions to form a hydrocracked product, wherein the base oil feedstock comprises vacuum gas oil having a front end cut point of about 700° F. or greater and a back end cut point of about 900° F. or less;   separating the hydrocracked product into a gaseous fraction and a liquid fraction;   contacting the liquid fraction with a dewaxing catalyst under hydroisomerization conditions, to produce a dewaxed product; and   optionally, contacting the dewaxed product with a hydrofinishing catalyst under hydrofinishing conditions to produce a hydrofinished dewaxed product;   wherein, the dewaxed product and/or the hydrofinished dewaxed product has a viscosity index of 120 or greater after dewaxing.   
     
     
         16 . The process of  claim 15 , wherein the dewaxed product and/or the hydrofinished dewaxed product has a viscosity index of 130 or greater after dewaxing, or 135 or greater after dewaxing, or 140 or greater after dewaxing. 
     
     
         17 . The process of  claim 15 , wherein the dewaxed product and/or the hydrofinished dewaxed product comprises a Group III or Group III+ base oil product. 
     
     
         18 . The process of  claim 15 , wherein the hydrocracked product has a viscosity index of at least about 135, or 140, or 145, or 150. 
     
     
         19 . The process of  claim 15 , wherein the waxy product yield at a viscosity of 4 cSt 100° C. of the vacuum gas oil having a front end cut point of about 700° F. or greater and a back end cut point of about 900° F. or less is at least about 3 lvol. % greater than the same process that does not include the vacuum gas oil having a front end cut point of about 700° F. or greater and a back end cut point of about 900° F. or less as the base oil feedstock. 
     
     
         20 . A process for making a base oil from a base oil feedstock, or a fraction thereof, the process comprising
 providing an atmospheric resid fraction from a base oil feedstock, or a fraction thereof;   separating the base oil feedstock, or a fraction thereof, and/or the base oil atmospheric resid fraction into a vacuum gas oil cut-point fraction having a front end cut point of about 700° F. or greater and a back end cut point of about 900° F. or less to form a medium vacuum gas oil MVGO fraction and a heavy vacuum gas oil HHVGO fraction; and   combining HHVGO fraction and a base oil feedstock to form a first base oil feedstream;   contacting the first base oil feedstream with a hydrocracking catalyst under hydrocracking conditions to form a hydrocracked product;   separating the hydrocracked product into a gaseous fraction and a liquid fraction;   contacting the liquid fraction with a dewaxing catalyst under hydroisomerization conditions, to produce a dewaxed product; and   optionally, contacting the dewaxed product with a hydrofinishing catalyst under hydrofinishing conditions to produce a hydrofinished dewaxed product; and/or   combining an atmospheric resid feedstock with the MVGO fraction to form a second base oil feedstream;   contacting the second base oil feedstream with a hydrocracking catalyst under hydrocracking conditions to form a hydrocracked product;   separating the hydrocracked product into at least a gaseous fraction and a liquid fraction;   contacting the liquid fraction with a dewaxing catalyst under hydroisomerization conditions, to produce a dewaxed product; and   optionally, contacting the dewaxed product with a hydrofinishing catalyst under hydrofinishing conditions to produce a hydrofinished dewaxed product.   
     
     
         21 . The process of  claim 20 , wherein the base oil feedstock comprises tight oil, or a fraction thereof. 
     
     
         22 . The process of  claim 21 , wherein the vacuum gas oil cut-point fraction is derived from the atmospheric resid fraction of the tight oil.