Hydroconversion process for making lubricating oil basestocks

Abstract

A process for producing a lubricating oil basestock having at least 90 wt. % saturates and a VI of at least 105 by selectively hydroconverting a raffinate from a solvent extraction zone in a two step hydroconversion zone followed by a hydrofinishing zone, and a lubricating oil basestock produced by said process.

What is claimed is:  
     
         1 . A process for producing a lubricating oil basestock which comprises: 
 (a) conducting a lubricating oil feedstock to a solvent extraction zone and under-extracting the feedstock to form an under-extracted raffinate wherein the extraction zone solvent contains water added in the amount from about 1 to about 10 vol. %, based on extraction solvent, such that the extraction solvent contains from 3 to 10 vol. % water;    (b) stripping the under-extracted raffinate of solvent to produce an under-extracted raffinate feed having a dewaxed oil viscosity index from about 75 to about 105;    (c) passing at least a portion of the raffinate feed to a first hydroconversion zone and processing the raffinate feed in the presence of a non-acidic catalyst at a temperature of from 320 to 420° C., a hydrogen partial pressure of from 1000 to 2500 psig (7.0 to 17.3 mPa), space velocity of 0.2 to 5.0 LHSV and a hydrogen to feed ratio of from 500 to 5000 Scf/B (89 to 890 m 3 /m 3 ) to produce a first hydroconverted raffinate;    (d) passing the hydroconverted raffinate from the first hydroconversion zone to a second hydroconversion zone and processing the hydroconverted raffinate in the presence of a non-acidic catalyst at a temperature of from 320 to 420° C. provided that the temperature in the second hydroconversion is not greater than the temperature in the first hydroconversion zone, a hydrogen partial pressure of from 1000 to 2500 psig (7.0 to 17.3 mPa), a space velocity of from 0.2 to 5.0 LHSV and a hydrogen to feed ratio of from 500 to 5000 Scf/B (89 to 890 m 3 /m 3 ) to produce a second hydroconverted raffinate;    (e) passing at least a portion of the second hydroconverted raffinate to a hydrofinishing reaction zone and conducting cold hydrofinishing of the second hydroconverted raffinate in the presence of a hydrofinishing catalyst which is at least one Group VIB or Group VIII metal on a refractory metal oxide support at a temperature of from 200 to 360° C., a hydrogen partial pressure of from 1000 to 2500 psig (7.0 to 17.3 mPa), a space velocity of from 0.2 to 10 LHSV and hydrogen to feed ratio of from 500 to 5000 Scf/B (89 to 890 m 3 /m 3 ) to produce a hydrofinished raffinate.    
     
     
         2 . The process of  claim 1  wherein the solvent extraction zone includes an extraction solvent selected from at least one of N-methyl-2-pyrrolidone, furfural and phenol.  
     
     
         3 . The process of  claim 2  wherein the extraction zone conditions include a solvent, oil ratio is from 0.5 to 5.0.  
     
     
         4 . The process of  claim 1  wherein the raffinate feed has a dewaxed oil viscosity index from about 80 to about 95.  
     
     
         5 . The process of  claim 1  wherein the non-acidic catalyst has an acidity less than about 0.5, said acidity being determined by the ability of the catalyst to convert 2-methyl-2-pentene to 3-methyl-2-pentene and 4-methyl-2-pentene and is expressed as the mole ratio of 3-methyl-2-pentene to 4-methyl-2-pentene.  
     
     
         6 . The process of  claim 1  wherein the non-acidic catalyst in the first hydroconversion zone is at least one of a Group VIB metal and non-noble Group VIII metal.  
     
     
         7 . The process of  claim 1  wherein the space velocity in the first and second hydroconversion zones is from about 0.3 to 3.0 LHSV.  
     
     
         8 . The process of  claim 1  wherein the temperature in the second hydroconversion zone is about 5 to 100° C. lower than the temperature in the first hydroconversion zone.  
     
     
         9 . The process of  claim 1  wherein the temperature in the hydrofinishing zone is from about 290 to 350° C.  
     
     
         10 . The process of  claim 1  wherein the catalyst in the hydrofinishing zone includes at least one Group VIII noble metal.  
     
     
         11 . The process of  claim 10  wherein the catalyst is Pt, Pd or a mixture thereof.  
     
     
         12 . The process of  claim 1  wherein the second hydroconverted raffinate is passed to a separator to separate low boiling products from hydroconverted raffinate prior to passing to the hydrofinishing reaction zone.  
     
     
         13 . The process of  claim 12  wherein hydroconverted raffinate from the separator is passed to a dewaxing zone and subjected to at least one of solvent dewaxing and catalytic dewaxing prior to passing to the hydrofinishing zone.  
     
     
         14 . The process of  claim 13  wherein catalytic dewaxing is accomplished with a dewaxing catalyst containing at least one 10 ring molecular sieve.  
     
     
         15 . The process of  claim 1  wherein the second hydroconverted raffinate is passed to a dewaxing zone and catalytically dewaxed using a sulfur and nitrogen tolerant molecular sieve prior to passing to the hydrofinishing zone.  
     
     
         16 . The process of  claim 1  wherein the hydrofinished raffinate is passed to a separator to separate low boiling products from the hydrofinished raffinate to produce a second hydrofinished raffinate.  
     
     
         17 . The process of  claim 16  wherein the second hydrofinished raffinate is passed to a dewaxing zone and subjected to at least one of solvent dewaxing and catalytic dewaxing to produce a dewaxed second hydrofinished raffinate.  
     
     
         18 . The process of  claim 17  wherein the catalytic dewaxing is accomplished with a dewaxing catalyst containing at least one 10 ring molecular sieve.  
     
     
         19 . The process of  claim 1  wherein the hydrofinished raffinate is passed to a dewaxing zone and dewaxed using a sulfur and nitrogen tolerant molecular sieve.  
     
     
         20 . The process of  claim 17  wherein the dewaxed second hydrofinished raffinate is further hydrofinished in a second hydrofinishing zone.  
     
     
         21 . The process of  claim 1  wherein the under-extracted raffinate feed is solvent dewaxed under solvent dewaxing conditions prior to entering the first hydroconversion zone.  
     
     
         22 . The process of  claim 1  additionally comprising adding additives to the lubricating oil basestock.  
     
     
         23 . The process of  claim 22  wherein the additives comprise at least one detergent, dispersant, antioxidant, friction modifier, demulsifier, VI improver and antifoamant.  
     
     
         24 . The process of  claim 1  wherein second hydroconversion zone additionally contains a catalytic dewaxing catalyst.  
     
     
         25 . A process for producing a lubricating oil basestock which comprises: 
 (a) conducting a lubricating oil feedstock, said feedstock being a distillate fraction, to a solvent extraction zone and under-extracting the feedstock to form an under-extracted raffinate;    (b) stripping the under-extracted raffinate of solvent to produce an under-extracted raffinate feed having a dewaxed oil viscosity index from about 75 to about 105;    (c) passing at least a portion of the raffinate feed to a hydroconversion zone and hydroconverting the raffinate feed under hydroconversion conditions to produce a basestock containing at least about 90% saturates and a VI less than about 120, said basestock having volatility-viscosity properties characterized by the equation N=(32−(4)(V))±1 where N is the Noack volatility and V is the viscosity in the range 3.5 to 6.0 cSt at 100° C.    
     
     
         26 . A process for producing a lubricating oil basestock which comprises: 
 (a) conducting a lubricating oil feedstock to a solvent extraction zone and under-extracting the feedstock to form an under-extracted raffinate wherein the extraction zone solvent contains water added in the amount from about 1 to about 10 vol. %, based on extraction solvent, such that the extraction solvent contains from 3 to 10 vol. % water;    (b) stripping the under-extracted raffinate of solvent to produce an under-extracted raffinate feed having a dewaxed oil viscosity index from about 75 to about 105;    (c) passing at least a portion of the raffinate feed to a first hydroconversion zone and processing the raffinate feed in the presence of a non-acidic catalyst at a temperature of from 320 to 420° C., a hydrogen partial pressure of from 1000 to 2500 psig (7.0 to 17.3 mPa), space velocity of 0.2 to 5.0 LHSV and a hydrogen to feed ratio of from 500 to 5000 Scf/B (89 to 890 m 3 /m 3 ) to produce a first hydroconverted raffinate;    (d) passing the hydroconverted raffinate from the first hydroconversion zone to a second hydroconversion zone and processing the hydroconverted raffinate in the presence of a non-acidic catalyst at a temperature of from 320 to 420° C. provided that the temperature in the second hydroconversion is not greater than the temperature in the first hydroconversion zone, a hydrogen partial pressure of from 1000 to 2500 psig (7.0 to 17.3 mPa), a space velocity of from 0.2 to 5.0 LHSV and a hydrogen to feed ratio of from 500 to 5000 Scf/B (89 to 890 m 3 /m 3 ) to produce a second hydroconverted raffinate;    (e) passing at least a portion of the second hydroconverted raffinate to a dewaxing zone and conducting at least one of catalytic and solvent dewaxing under dewaxing conditions to produce a dewaxed hydroconverted raffinate;    (f) passing at least a portion of the dewaxed hydroconverted raffinate to a hydrofinishing reaction zone and conducting cold hydrofinishing of the second hydroconverted raffinate in the presence of a hydrofinishing catalyst which is at least one Group VIB or Group VIII metal on a refractory metal oxide support at a temperature of from 200 to 360° C., a hydrogen partial pressure of from 1000 to 2500 psig (7.0 to 17.3 mPa), a space velocity of from 0.2 to 10 LHSV and hydrogen to feed ratio of from 500 to 5000 Scf/B (89 to 890 m 3 /m 3 ) to produce a hydrofinished raffinate.