Method for producing lubricating base oil with low cloud point and high viscosity index

Abstract

The present invention relates to a method for producing lubricating base oil with a low cloud point and a high viscosity index. In the method, a lubricating base oil with a low pour point, a low cloud point and a high viscosity index is produced by a hydrorefining-isomerization/asymmetrical cracking-hydrofinishing in the presence of hydrogen, wherein a highly waxy heavy fraction oil having an initial boiling point of 300° C. to 460° C., a wax content of 5% or more, a pour point of −20° C. or more and a cloud point of −5° C. or more is used as a raw material, and naphtha and middle fraction oil being co-produced. The method is characterized mainly in the high yield of heavy base oil, a low pour point and cloud point, a high viscosity and viscosity index of the base oil.

1 . A method for producing a lubricating base oil with a low cloud point and a high viscosity index, wherein the cloud point is lower than −5° C., and the viscosity index is higher than 120, the method comprises: producing a lubricating base oil by a hydrorefining-isomerization/asymmetrical cracking-hydrofinishing in the presence of hydrogen, wherein a highly waxy heavy fraction oil having an initial boiling point of 300° C. to 460° C., a wax content of 5% or more, a pour point of −20° C. or more and a cloud point of −5° C. or more is used as a raw material;
 (1) during the hydrorefining process, a wax-containing heavy feed stock contacts a pre-refining catalyst, and is subjected to desulfurization, denitrogenation, aromatic saturation and a ring-opening reaction, a light product generated in the hydrorefining process is separated by a stripping column as a byproduct, and a heavy product enters an isomerization-asymmetrical cracking process; 
 the operating conditions of the hydrorefining process are: reaction temperature: 350° C. to 410° C., hydrogen partial pressure: 10 MPa to 18 MPa, space velocity: 0.5 h −1  to 2.0 h −1 , volume ratio of hydrogen to oil:300 Nm 3 /m 3  to 1000 Nm 3 /m 3 ; 
 the pre-refining catalyst comprises 60 wt % to 90 wt % of one or more of alumina, silica and titania, and 10 wt % to 40 wt % of one or more of molybdenum trioxide, tungsten trioxide, nickel oxide and cobalt oxide; 
 (2) during the hydrogenation isomerization-asymmetrical cracking process, the heavy product generated in the hydrorefining process contacts an isomerization-asymmetrical cracking catalyst, wax-containing component having a high pour point is subjected to an isomerization-asymmetrical cracking reaction, and is converted into a an isomer and an asymmetrical cracking product having a low pour point, which then directly enters a hydrofinishing process; 
 the operating conditions of the hydrogenation isomerization-asymmetrical cracking process are: reaction temperature: 260° C. to 410° C., hydrogen partial pressure: 10 MPa to 18 MPa, volume space velocity: 0.5 h −1  to 3.0 h −1 , volume ratio of hydrogen to oil:300 Nm 3 /m 3  to 1000 Nm 3 /m 3 ; 
 the catalyst: the content of mesoporous molecular sieve is 40% to 80%, the content of Pt and/or Pd is 0.3 wt % to 0.7 wt %, and alumina as the balance; 
 (3) during the hydrofinishing process, an isomerization-asymmetrical cracking reaction product having a low pour point contacts a hydrofinishing catalyst, residual aromatics and olefins generated by the asymmetrical cracking reaction are hydrogenated and saturated, and the resulting product is separated by a fractionating column to obtain a lubricating base oil and gaseous hydrocarbons, naphtha and middle fraction oil; 
 the catalyst comprises amorphous silica-alumina and at least one group VIII noble metal, the weight ratio of SiO 2 :Al 2 O 3  is 1:1˜9, the average pore size is 1.0 nm to 5.0 nm, the pore volume is 0.3 ml/g to 1.0 mug, the BET specific surface area is 260 m 2 /g to 450 m 2 /g; the noble metal is Pt and/or Pd, and the content of the noble metal is 0.3 wt % to 0.6 wt %; and 
 the hydrofinishing reaction conditions are: reaction temperature: 180° C. to 320° C., hydrogen partial pressure: 10 MPa to 18 MPa, volume space velocity: 0.5 h −1  to 3.0 h −1 , volume ratio of hydrogen to oil:300 Nm 3 /m 3  to 1000 Nm 3 /m 3 . 
 
     
     
         2 . The method for producing a lubricating base oil with a low cloud point of and a high viscosity index according to  claim 1 , wherein the heavy feed stock comprises anyone of furfural refined oil, foots oil, cerate, propane deasphalted oil, hydrocracking UCO, vacuum gas oil and Fischer-Tropsch wax or a mixture thereof. 
     
     
         3 . The method for producing a lubricating base oil with a low cloud point of and a high viscosity index according to  claim 1 , wherein the mesoporous molecular sieve used in the hydrogenation isomerization-asymmetrical cracking reaction catalyst is one of a ZSM-22/ZSM-23 composite molecular sieve, a ZSM-23/ZSM-22 composite molecular sieve, a ZSM-22/SAPO-11 composite molecular sieve, a ZSM-23/SAPO-11 composite molecular sieve, a ZSM-5/SAPO-11 composite molecular sieve and an EU-1/SAPO-11 composite molecular sieve. 
     
     
         4 . A method for producing a lubricating base oil comprising:
 (1) contacting a wax-containing heavy feed stock with a pre-refining catalyst and separating a light product from a heavy product;   (2) contacting the heavy product with an isomerization-asymmetrical cracking catalyst wherein a wax-containing component having a high pour point is subjected to an isomerization-asymmetrical cracking reaction, and is converted into an isomer and an asymmetrical cracking product having a low pour point;   (3) contacting the isomer and the isomerization-asymmetrical cracking reaction product having a low pour point with a hydrofinishing catalyst to generate a product; and   (4) separating the product by a fractionating column to obtain a lubricating base oil and gaseous hydrocarbons, naphtha and middle fraction oil.   
     
     
         5 . The method of  claim 4 , wherein the lubricating base oil has a low cloud point and a high viscosity index. 
     
     
         6 . The method of  claim 5 , wherein the cloud point is lower than −5° C., and the viscosity index is higher than 120. 
     
     
         7 . The method of  claim 4 , wherein the wax-containing heavy feed stock has an initial boiling point of 300° C. to 460° C., a wax content of 5% or more, a pour point of −20° C. or more and a cloud point of −5° C. 
     
     
         8 . The method of  claim 4 , wherein the contacting at step (1) subjects the wax-containing heavy feed stock to desulfurization, denitrogenation, aromatic saturation and a ring-opening reaction. 
     
     
         9 . The method of  claim 4 , wherein operating conditions of the contacting at step (1) comprise a reaction temperature of from 350° C. to 410° C.; a hydrogen partial pressure of 10 MPa to 18 MPa; a space velocity of from 0.5 h −1  to 2.0 h −1 ; and a volume ratio of hydrogen to oil of from 300 Nm 3 /m 3  to 1000 Nm 3 /m 3 . 
     
     
         10 . The method of  claim 4 , wherein the pre-refining catalyst comprises from 60 wt. % to 90 wt. % of one or more of alumina, silica and titania; and 10 wt. % to 40 wt. % of one or more of molybdenum trioxide, tungsten trioxide, nickel oxide and cobalt oxide. 
     
     
         11 . The method of  claim 4 , wherein the contacting at step (2) subjects the heavy product is subjected to an isomerization-asymmetrical cracking reaction, and is converted into a an isomer and an asymmetrical cracking product having a low pour point. 
     
     
         12 . The method of  claim 4 , wherein operating conditions of the contacting at step (2) comprise a reaction temperature of from 260° C. to 410° C.; a hydrogen partial pressure of from 10 MPa to 18 MPa; a volume space velocity of from 0.5 h −1  to 3.0 h −1 ; and a volume ratio of hydrogen to oil of from 300 Nm 3 /m 3  to 1000 Nm 3 /m 3 . 
     
     
         13 . The method of  claim 4 , wherein the isomerization-asymmetrical cracking catalyst comprises 40% to 80% mesoporous molecular sieve; a Pt and/or Pd content of 0.3 wt % to 0.7 wt %; and alumina as the balance. 
     
     
         14 . The method of  claim 13 , wherein the mesoporous molecular sieve is at least one of a ZSM-22/ZSM-23 composite molecular sieve, a ZSM-23/ZSM-22 composite molecular sieve, a ZSM-22/SAPO-11 composite molecular sieve, a ZSM-23/SAPO-11 composite molecular sieve, a ZSM-5/SAPO-11 composite molecular sieve or an EU-1/SAPO-11 composite molecular sieve. 
     
     
         15 . The method of  claim 4 , wherein the contacting at step (3) hydrogenates and saturates residual aromatics and olefins generated by the asymmetrical cracking reaction. 
     
     
         16 . The method of  claim 4 , wherein operating conditions of the contacting at step (3) comprise a reaction temperature of from 180° C. to 320° C.; a hydrogen partial pressure of from 10 MPa to 18 MPa; a volume space velocity of from 0.5 h −1  to 3.0 h −1 ; and a volume ratio of hydrogen to oil of from 300 Nm 3 /m 3  to 1000 Nm 3 /m 3 . 
     
     
         17 . The method of  claim 4 , wherein the hydrofinishing catalyst comprises amorphous silica (SiO 2 )-alumina (Al 2 O 3 ) and at least one group VIII noble metal, wherein the weight ratio of SiO 2 :Al 2 O 3  is 1:1˜9; the average pore size is from 1.0 nm to 5.0 nm; the pore volume is from 0.3 mL/g to 1.0 mL/g; the BET specific surface area is from 260 m 2 /g to 450 m 2 /g; the noble metal is Pt and/or Pd; and the content of the noble metal is from 0.3 wt % to 0.6 wt %. 
     
     
         18 . The method of  claim 4 , wherein the isomer and an asymmetrical cracking product having a low pour point directly enter the contacting at step (3). 
     
     
         19 . The method of  claim 4 , wherein the heavy feed stock comprises any one of furfural refined oil, foots oil, cerate, propane deasphalted oil, hydrocracking UCO, vacuum gas oil and Fischer-Tropsch wax or a mixture thereof.