Production of lubricant oils from thermally cracked resids

Abstract

Methods are provided for processing deasphalted gas oils derived from thermally cracked resid fractions to form Group I, Group II, and/or Group III lubricant base oils. The yield of lubricant base oils (optionally also referred to as base stocks) can be increased by thermally cracking a resid fraction at an intermediate level of single pass severity relative to conventional methods. By performing thermal cracking to a partial level of conversion, compounds within a resid fraction that are beneficial for increasing both the viscosity and the viscosity index of a lubricant base oil can be retained, thus allowing for an improved yield of higher viscosity lubricant base oils from a thermally cracked resid fraction.

What is claimed is: 
     
         1 . A method for producing a lubricant base oil product, comprising:
 providing a feedstock comprising a 650° F.+ (343° C.) fraction, at least 10 wt % of the 650° F.+ fraction comprising a portion having a boiling point of at least 1050° F. (566° C.);   exposing at least a portion of the 650° F.+ (343° C.) fraction to effective thermal cracking conditions to form a thermal cracking effluent, the thermal cracking effluent comprising at least a first thermal cracking effluent fraction having a 10% distillation point of at least 700° F. (371° C.) and a second thermal cracking effluent fraction having a lower boiling range, the effective thermal cracking conditions being selected for single pass conversion of 30 wt % to 80 wt % of the portion having a boiling point of at least 1050° F. (566° C.); and   deasphalting at least a portion of the first thermal cracking effluent fraction to form at least a deasphalted thermal cracking effluent and a deasphalting residue;   wherein at least a first portion of the deasphalted thermal cracking effluent has a viscosity index of at least 50 and a viscosity at 100° C. of at least 7.0 cSt.   
     
     
         2 . The method of  claim 1 , wherein the at least a first portion of the deasphalted thermal cracking effluent having a viscosity index of at least 50 and a viscosity of at least 7.0 cSt at 100° C. comprises a raffinate from performing a solvent extraction on at least a second portion of the deasphalted thermal cracking effluent, a raffinate yield from performing the solvent extraction on the at least a second portion of the deasphalted thermal cracking effluent optionally being at least 30 wt %. 
     
     
         3 . The method of  claim 1 , the method further comprising:
 exposing the at least a first portion of the deasphalted thermal cracking effluent to a dewaxing catalyst under effective catalytic dewaxing conditions and a hydrofinishing catalyst under effective hydrofinishing conditions, to form a dewaxed, hydrofinished effluent,   wherein the dewaxed, hydrofinished effluent has a viscosity index that is at least 5 greater than the viscosity index of the at least a portion of the deasphalted thermal cracking effluent.   
     
     
         4 . The method of  claim 1 , wherein at least 50 wt % of the 650° F.+ (343° C.) fraction has a boiling point of at least 1050° F. (566° C.), wherein the first thermal cracking effluent fraction has a T95 boiling point of at least 1050° F. (566° C.), or a combination thereof. 
     
     
         5 . The method of  claim 1 , wherein the at least a first portion of the deasphalted thermal cracking effluent has a viscosity index of at least 80, or wherein the at least a first portion of the deasphalted thermal cracking effluent has a viscosity at 100° C. of at least 8.0 cSt, or a combination thereof. 
     
     
         6 . The method of  claim 1 , further comprising hydrotreating the at least a first portion of the deasphalted thermal cracking effluent under effective hydrotreating conditions to form a hydrotreated deasphalted thermal cracking effluent having a sulfur content of 300 wppm or less. 
     
     
         7 . The method of  claim 1 , further comprising hydrocracking at least a second portion of the deasphalted thermal cracking effluent under effective hydrocracking conditions to form a hydrocracked deasphalted thermal cracking effluent having a sulfur content of 300 wppm or less, the at least a first portion of the deasphalted thermal cracking effluent comprising at least a portion of the hydrocracked deasphalted thermal cracking effluent. 
     
     
         8 . The method of  claim 1 , wherein the effective thermal cracking conditions comprise hydroconversion conditions, the hydroconversion conditions including a temperature of at least 400° C. and a hydrogen partial pressure of 1500 psig (10.3 MPa) or less. 
     
     
         9 . The method of  claim 1 , wherein the effective thermal cracking conditions comprise fluidized coking conditions, including a temperature of at least 500° C. and a pressure of 50 psig (345 kPa) or less. 
     
     
         10 . A method for producing a lubricant base oil product, comprising:
 providing a feedstock comprising a 650° F.+ (343° C.) fraction, at least 10 wt % of the 650° F.+ fraction comprising a portion having a boiling point of at least 1050° F. (566° C.);   deasphalting a first portion of the feedstock to form at least a first deasphalted oil and a first deasphalting residual product;   exposing at least a first portion of first deasphalting residual product to effective thermal cracking conditions to form a thermal cracking effluent, the thermal cracking effluent comprising at least a first thermal cracking effluent fraction having a 10% distillation point of at least 650° F. (343° C.) and a second thermal cracking effluent fraction having a lower boiling range, the effective thermal cracking conditions being selected for single pass conversion of 50 wt % to 80 wt % of the portion having a boiling point of at least 1050° F. (566° C.);   deasphalting at least a portion of the first thermal cracking effluent fraction to form at least a deasphalted thermal cracking effluent, the deasphalted thermal cracking effluent having a first viscosity index;   exposing at least a portion of the deasphalted thermal cracking effluent to a hydrocracking catalyst under effective hydrocracking conditions to form a hydrocracked effluent; and   exposing at least a portion of the hydrocracked effluent to a dewaxing catalyst under effective catalytic dewaxing conditions, and a hydrofinishing catalyst under effective hydrofinishing conditions, to form one or more lubricant products, the one or more lubricant products having a viscosity of at least 6 cSt at 100° C. and a viscosity index of at least 90, a yield of the one or more lubricant products being at least 15 wt % of the 650° F.+ (343° C.) fraction of the feedstock.   
     
     
         11 . The method of  claim 10 , further comprising combining a second portion of the feedstock and a second portion of the first deasphalting residual product to form an asphalt feed. 
     
     
         12 . The method of  claim 10 , further comprising at least one of:
 a) forming a Group I base oil from the first deasphalted oil, the forming a Group I base oil comprising:
 solvent extracting at least a portion of the first deasphalted oil to form an extraction raffmate; and 
 solvent dewaxing at least a portion of the extraction raffmate to form a Group I base oil; or 
   b) forming a base oil from the first deasphalted oil, the forming a base oil comprising:
 hydrocracking at least a portion of the first deasphalted oil in the presence of a hydrocracking catalyst to form a hydrocracked effluent; 
 dewaxing at least a portion of the hydrocracked effluent in the presence of a dewaxing catalyst and hydrofinishing at least a portion of the hydrocracked effluent in the presence of a hydrofinishing catalyst to form a base oil. 
   
     
     
         13 . The method of  claim 10 , wherein deasphalting a feedstock comprising a 650° F.+ (343° C.) fraction comprises deasphalting a feedstock comprising the 650° F.+ fraction and a recycled fraction,
 wherein exposing at least a portion of the deasphalting residual product to effective thermal cracking conditions further comprises forming a third thermal cracking effluent having a 10% distillation point of at least 800° F. (427° C.), 
 wherein the method further comprises recycling at least a portion of the third thermal cracking effluent as the recycled fraction, and 
 wherein exposing at least a portion of the deasphalted thermal cracking effluent to a hydrocracking catalyst comprises exposing at least a portion of the deasphalted thermal cracking effluent and at least a portion of the first deasphalted oil. 
 
     
     
         14 . The method of  claim 13 , wherein the effective thermal cracking conditions comprise fluidized coking conditions, including a temperature of at least 500° C. and a pressure of 50 psig (345 kPa) or less. 
     
     
         15 . A naphthenic base oil composition comprising:
 a) at least 40 wt % naphthenes and having a viscosity index of at least 120, the naphthenic base oil having a viscosity at 100° C. of at least 10 cSt; or   b) at least 20 wt % 3+ ring naphthenes having a viscosity of at least 15 cSt at 100° C. and a viscosity index of 80-120.   
     
     
         16 . The naphthenic base oil composition of  claim 15 , wherein the naphthenic base oil comprising at least 20 wt % 3+ ring naphthenes further comprises at least 40 wt % naphthenes. 
     
     
         17 . A deasphalted oil formed from propane deasphalting of a thermally cracked gas oil composition, the thermally cracked gas oil composition having a wt % distillation point of at least 343° C., 2.0 wt %-5.0 wt % of micro-carbon residue, and an API gravity of 15 or less, at least 15 wt % of the thermally cracked gas oil composition having boiling point of greater than 510° C., the thermally cracked gas oil composition having a kinematic viscosity at 100° C. of at least 8 cSt. 
     
     
         18 . The deasphalted oil of  claim 17 , wherein the thermally cracked gas oil composition comprises at least 15 wt % olefins. 
     
     
         19 . The deasphalted oil of  claim 17 , wherein the thermally cracked gas oil composition comprises at least 0.03 wt % of n-heptane insolubles, 0.1 wt % to 2.0 wt % of pentane insolubles, or a combination thereof. 
     
     
         20 . The deasphalted oil of  claim 17 , wherein the thermally cracked gas oil composition is formed by the method comprising:
 providing a feedstock comprising a 343° C.+ fraction, at least 10 wt % of the 343° C.+ fraction comprising a portion having a boiling point of at least 566° C.;   exposing at least a portion of the 343° C.+ fraction to effective thermal cracking conditions to form a thermal cracking effluent, the thermal cracking effluent comprising at least the thermally cracked gas oil composition and a second thermal cracking effluent fraction having a lower boiling range, the effective thermal cracking conditions being selected for conversion of 30 wt % to 80 wt % of the portion having a boiling point of at least 1050° F.