Catalytic and solvent processing for base oil production

Abstract

Methods are provided for producing lubricant base oils using a combination of catalytic and solvent processing. By using a combination of catalytic processing for feed conversion and dewaxing while using solvent processing for removal of aromatics, Group II and Group III lubricant base oils can be produced using low pressure catalytic processes.

What is claimed is: 
     
         1 . A method for forming a lubricant base stock, comprising:
 hydroprocessing a feedstock having a T5 boiling point greater than 600° F. (316° C.) and a sulfur content of at least 500 wppm under effective hydroprocessing conditions to form a hydroprocessed effluent, the effective hydroprocessing conditions including a total pressure of less than 1500 psig (10.3 MPag);   separating the hydroprocessed effluent to form at least a gas phase effluent and a hydroprocessed liquid product effluent having a sulfur content of less than 500 wppm;   dewaxing at least a first portion of the hydroprocessed liquid product effluent to form a dewaxed effluent;   extracting at least a second portion of the hydroprocessed liquid product effluent in the presence of an extraction solvent to form a raffinate product and an extract product, the raffinate product having a sulfur content of 300 wppm or less; and   fractionating at least a portion of the raffinate product to form at least a lubricant base stock product having a viscosity index of at least 80, and an aromatics content of 2.5 wt % or less.   
     
     
         2 . The method of  claim 1 , wherein dewaxing at least a first portion of the hydroprocessed liquid product effluent comprises exposing the at least a first portion of the hydroprocessed liquid product effluent to a dewaxing catalyst under effective catalytic dewaxing conditions to form the dewaxed effluent, the effective catalytic dewaxing conditions including a total pressure of 300 psig (2.1 MPag) to 700 psig (4.8 MPag), wherein extracting at least a second portion of the hydroprocessed liquid product effluent comprises extracting at least a portion of the dewaxed effluent. 
     
     
         3 . The method of  claim 2 , wherein the effective dewaxing conditions comprise a total pressure of 400 psig (2.8 MPag) to 600 psig (4.2 MPag), the effective dewaxing conditions are effective for conversion of 1 wt % to 10 wt % of the at least a portion of the hydroprocessed liquid product effluent, or a combination thereof 
     
     
         4 . The method of  claim 2 , wherein the dewaxed effluent has an aromatics content of 5 wt % to 30 wt %. 
     
     
         5 . The method of  claim 1 , further comprising hydrofining at least a portion of the raffinate product under effective hydrofining conditions to form a hydrofined raffinate, wherein dewaxing at least a first portion of the hydroprocessed liquid product effluent comprises solvent dewaxing at least a portion of the hydrofined raffinate. 
     
     
         6 . The method of  claim 1 , further comprising hydrofinishing at least a portion of the dewaxed effluent under effective hydrofinishing conditions. 
     
     
         7 . The method of  claim 1 , wherein fractionating the at least a portion of the raffinate product further comprises forming a distillate boiling range product. 
     
     
         8 . The method of  claim 1 , further comprising separating the dewaxed effluent to form a fraction having a T5 boiling point of at least 500° F. (260° C.) and at least one fuel product, the at least one fuel product being a naphtha boiling range product or a distillate fuel boiling range product, wherein extracting at least a portion of the dewaxed effluent comprises extracting at least a portion of the fraction having a T5 boiling point of at least 500° F. (260° C.). 
     
     
         9 . The method of  claim 1 , wherein separating the hydroprocessed effluent further comprises forming at least one fuel product, the at least one fuel product being a naphtha boiling range product or a distillate fuel boiling range product. 
     
     
         10 . The method of  claim 1 , wherein the effective hydroprocessing conditions comprise a total pressure of 750 psig (5.2 MPag) to 1500 psig (10.4 MPag), the effective hydroprocessing conditions comprise effective hydrotreating conditions or effective hydrocracking conditions, or a combination thereof. 
     
     
         11 . The method of  claim 1 , wherein the effective hydroprocessing conditions are effective for conversion of 5 wt % to 30 wt % of the feedstock having a T5 boiling point greater than 600° F. (316° C.) relative to a conversion temperature of 700° F. (371° C.). 
     
     
         12 . The method of  claim 1 , wherein the hydroprocessed liquid product effluent has a sulfur content of 100 wppm or less. 
     
     
         13 . The method of  claim 1 , wherein the extraction solvent is methyl pyrollidone (NMP), furfural, phenol, SO 2 , sulfolane, dimethylsulfoxide, or combination thereof. 
     
     
         14 . A method for forming a lubricant base stock, comprising:
 hydroprocessing a feedstock having a T5 boiling point greater than 600° F. (316° C.) and a sulfur content of at least 500 wppm under effective hydroprocessing conditions to form a hydroprocessed effluent, the effective hydroprocessing conditions including a total pressure of less than 1500 psig;   separating the hydroprocessed effluent to form at least a gas phase effluent and a hydroprocessed liquid product effluent having a sulfur content of less than 500 wppm;   exposing at least a portion of the hydroprocessed liquid product effluent to a dewaxing catalyst under effective catalytic dewaxing conditions to form a dewaxed effluent, the effective catalytic dewaxing conditions including a total pressure of 300 psig to 700 psig;   extracting at least a portion of the dewaxed effluent in the presence of an extraction solvent to form a raffinate product and an extract product, the raffinate product having a sulfur content of 300 wppm or less; and   fractionating at least a portion of the raffinate product to form at least a lubricant base stock product having a viscosity index of at least 80, and an aromatics content of 2.5 wt % or less.   
     
     
         15 . A method for forming a lubricant base stock, comprising:
 hydroprocessing a feedstock having a T5 boiling point greater than 600° F. (316° C.) and a sulfur content of at least 500 wppm under effective hydroprocessing conditions to form a hydroprocessed effluent;   exposing at least a portion of the hydroprocessing effluent to a dewaxing catalyst under effective catalytic dewaxing conditions to form a hydroprocessed, dewaxed effluent, the hydroprocessed, dewaxed effluent comprising a lubricant base oil fraction having an aromatics content of at least 3 wt %, the lubricant base oil fraction including a first lubricant base oil portion and a second lubricant base oil portion;   exposing the first lubricant base oil portion to an adsorbent to form an aromatics-depleted first lubricant base oil portion, the first lubricant base oil portion comprising 20 wt % to 70 wt % of the lubricant base oil fraction, an aromatics content of the aromatics-depleted first lubricant base oil portion being 500 wppm or less; and   combining the aromatics-depleted first lubricant base oil portion with the second lubricant base oil portion.   
     
     
         16 . The method of  claim 15 , wherein the adsorbent comprises one or more of zeolites, active carbon, mesoporous silica, materials corresponding to the M41S family of materials, and sulfonated polymers. 
     
     
         17 . The method of  claim 15 , wherein the adsorbent comprises one or more of zeolite Beta, USY, zeolite 5A, zeolite 13X, MCM-22, MCM-68, ZSM-5, MCM-41, Amberlyst acid ion exchanged resin and Nafion. 
     
     
         18 . The method of  claim 15 , wherein the adsorbent comprises metal cations, the metal cations comprising cations of Ag, Na, Ca, Cu, or a combination thereof. 
     
     
         19 . The method of  claim 15 , further comprising exposing the adsorbent to a desorption solvent to form an aromatics extract fraction. 
     
     
         20 . The method of  claim 15 , further comprising hydrofinishing at least a portion of the hydroprocessed, dewaxed effluent to form a hydrofinished effluent, the hydrofinished effluent comprising the lubricant base oil fraction.