Process for the hydroisomerization of Fischer-Tropsch wax to produce lubricating oil (OP-3403)
AssigneeExxon Research & Engineering Co.
InventorsGlen P. Hamner, deceased, Heather A. Boucher, William A. Wachter
Life of this patent
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Abstract
Fischer-Tropsch wax is converted to a lubricating oil having a high viscosity index and a low pour point by first hydrotreating the wax under relatively severe conditions and thereafter hydroisomerizing the hydrotreated wax in the presence of hydrogen on a particular fluorided Group VIII metal-on-alumina catalyst. The hydroisomerate is then dewaxed to produce a premium lubricating oil base stock.
Claims14
A process for producing a lubricating oil having a high viscosity index and a low pour point from a Fischer-Tropsch wax, which process comprises:
- (a) contacting the Fischer-Tropsch wax with hydrogen and a hydrotreating catalyst comprising Co, Ni, Mo or W or any mixture of two or more of said metals to reduce the oxygenate and trace metal levels of the wax and to partially hydrocrack and isomerize the wax;
- (b) contacting the hydrotreated Fischer-Tropsch wax from step (a) with hydrogen in a hydrosiomerization zone in the presence of a fluorided Group VIII metal-on-alumina catalyst having (i) a bulk fluoride concentration ranging from about 2 to about 10 weight percent, wherein the fluoride concentration is less than about 3.0 weight percent at the outer surface layer to a depth less than one one hundredth of an inch, provided the surface fluoride concentration is less than a bulk fluoride concentration, (ii) an aluminum fluoride hydroxide hydrate level greater than 60 where an aluminum fluoride hydrate level of 100 corresponds to the X-ray diffraction peak height of 5.66.ANG. for a Reference Standard, and (iii) a N/Al ratio less than about 0.005;
- (c) fractionating the effluent from step (b) to produce a lubricating oil fraction boiling above about 640.degree. F. at atmospheric pressure;
- and
- (d) dewaxing the lubricating oil fraction from step (c) to produce a dewaxed lubricating oil having a viscosity index of at least 130 and a pour point less than about 0.degree. F.
The process of claim 5, wherein about 10-30 wt% of the Fischer-Tropsch wax introduced into the hydroisomerization zone is converted to distillate and lighter products.
The process of claim 6 wherein the lubricating oil fraction recovered from step (c) has a boiling point in the range of about 700.degree. F.-1000.degree. F.
The process of claim 7 wherein the fluorided platinum-on-alumina catalyst has an aluminum fluoride hydroxide hydrate level of at least about 100.
The process of claim 8 wherein a residual fraction is recovered from step (c) and said residual fraction is recycled to the hydroisomerization zone.
The process of claim 9 wherein the effluent from the hydroisomerization zone is contacted with hydrogen and a hydrogenation catalyst under mild hydrofinishing conditions including a temperature of about 340.degree. F.-450.degree. F. and a pressure about 300 psi-1500 psi.
The process of claim 10 wherein the hydrogenation catalyst is a fluorided Group VIII metal on an alumina-containing base catalyst.
A process for producing a lubricating oil having a high viscosity index and a low pour point from a Fischer-Tropsch wax, which process comprises:
- (a) contacting the Fischer-Tropsch wax with hydrogen and an unsulfided hydrotreating catalyst comprising Co, Ni, Mo or W or any mixture of two or more of said metals to reduce the oxygenate and trace metal levels of the wax and to partially hydrocrack and isomerize the wax;
- (b) contacting the hydrotreated Fischer-Tropsch wax from step (a) with hydrogen in a hydroisomerization zone in the presence of a fluorided platinum-on-alumina catalyst having (i) a bulk fluoride concentration ranging from about 2 to about 10 weight percent, wherein the fluoride concentration is less than about 3.0 weight percent at the outer surface layer to a depth less than one one hundredth of an inch, provided the surface fluoride concentration is less than the bulk fluoride concentration, (ii) an aluminum fluoride hydrate level greater than 60 where an aluminum fluoride hydrate level of 100 corresponds to the X-ray diffraction peak height of 5.66.ANG. for a Reference Standard, and (iii) a N/Al ratio less than about 0.005,
- (c) contacting the isomerate from step (b) with hydrogen and the platinum-on-alumina catalyst defined in step (b) in a hydrofinishing zone run at mild conditions to reduce unsaturation of the isomerate and thereby improve its daylight stability and oxidation stability,
- (d) fractionating the effluent from step (c) to produce a lubricating oil fraction boiling above about 700.degree. F. at atmospheric pressure;
- and
- (e) dewaxing the lubricating oil fraction from step (d) to produce a dewaxed lubricating oil having a viscosity index of at least 140 and a pour point less than about -6.degree. F.
The process of claim 14 wherein about 15-30 wt% of the Fischer-Tropsch wax introduced into the hydroisomerization zone is converted therein to distillate and lower boiling material.
Dependencies are inferred from the claim text.