Production of high quality lubricant bright stock

Abstract

A process for producing a lubricant bright stock from a very heavy feed obtained from a petroleum crude is disclosed. The bright stock produced by the present process has a reduced cloud point and better oxidation stability relative to bright stocks prepared by conventional methods. The process comprises the steps of providing a petroleum residuum-derived stream; separating the residuum-derived stream at a distillation cut point in the range of 1150° F. to 1300° F., into a heavy fraction and at least one light fraction; hydrocracking the at least one light fraction under conditions to reduce the concentration of sulfur and nitrogen to suitable levels for hydroisomerization dewaxing; and dewaxing at least a portion of the hydrocracked stream under hydroisomerization conditions to produce a lubricant bright stock.

1 . A process for producing stable lubricant bright stock comprising the steps of: 
 a) providing a petroleum residuum-derived stream having a sulfur content of less than I % and a nitrogen content of less than 0.5%;    b) separating the residuum-derived stream at a distillation cut point in the range of 1150° F. to 1300° F., into a heavy fraction and at least one light fraction;    c) hydrocracking the at least one light fraction under lube hydrocracking in a lube hydrocracking zone in the presence of a hydrocracking catalyst and hydrogen under conditions to reduce the concentration of sulfur and nitrogen to suitable levels for hydroisomerization dewaxing; and    d) dewaxing at least a portion of the hydrocracked stream in an hydroisomerization zone in the presence of a hydroisomerization catalyst and hydrogen under hydroisomerization conditions to produce a lubricant bright stock.    
     
     
         2 . The process of  claim 1 , wherein the petroleum residuum-derived stream is a hydrocracked deasphalted oil.  
     
     
         3 . The process of  claim 1 , wherein the petroleum residuum-derived stream is a hydrocracked residuum.  
     
     
         4 . The process of  claim 1 , wherein the petroleum residuum-derived stream has a concentration of sulfur of less than 0.5% and a concentration of nitrogen of less than 0.2%.  
     
     
         5 . The process of  claim 1 , further comprising stabilizing the lubricant bright stock in a hydrofinishing zone in the presence of a hydrofinishing catalyst and hydrogen under hydrofinishing conditions.  
     
     
         6 . The process of  claim 5 , further comprising contacting the stabilized lubricant bright stock with clay in a clay treatment zone.  
     
     
         7 . The process of  claim 1 , wherein the bright stock has a viscosity, measured at 100° C., of greater than 15 cSt and viscosity index of greater than 80.  
     
     
         8 . The process of  claim 7 , wherein the bright stock has a viscosity index of greater than 90.  
     
     
         9 . The process of  claim 1 , wherein the bright stock has a viscosity in the range of 20 and 60 cSt, measured at 100° C.  
     
     
         10 . The process according to  claim 1 , wherein the hydroisomerization catalyst is selected from the group consisting of SAPO-11, SAPO-31, SAPO-41, SM-3, ZSM-22, ZSM-23, ZSM-35, ZSM-48, ZSM-57, SSZ-32, offretite, ferrierite and combinations thereof.  
     
     
         11 . The process according to  claim 10 , wherein the hydroisomerization catalyst is selected from the group consisting of SAPO-11, SAPO-31, SM-3, SSZ-32, and ZSM-23.  
     
     
         12 . The process according to  claim 11 , wherein the hydroisomerization catalyst is selected from the group consisting of SAPO-11, SM-3, SSZ-32, and ZSM-23.  
     
     
         13 . The process according to  claim 1 , wherein the hydroisomerization catalyst has a metal hydrogenation component.  
     
     
         14 . The process according to  claim 13 , wherein the metal hydrogenation component is platinum, palladium, or a mixture thereof.  
     
     
         15 . The process according to  claim 10  wherein the metal hydrogenation component is platinum.  
     
     
         16 . The process according to  claim 1 , wherein the suitable levels for hydroisomerization dewaxing include a concentration of nitrogen of less than 50 ppm and a concentration of sulfur of less than 100 ppm.  
     
     
         17 . The process according to  claim 1 , wherein the suitable levels for hydroisomerization dewaxing include a concentration of nitrogen of less than 30 ppm and a concentration of sulfur of less than 50 ppm.  
     
     
         18 . The process according to  claim 1 , wherein the suitable levels for hydroisomerization dewaxing include a concentration of nitrogen of less than 10 ppm and a concentration of sulfur of less than 20 ppm.