Claims
- 1. A process for dewaxing a hydrocarbon feedstock by (i) catalytically dewaxing the feedstock in at least two sequential catalytic dewaxing steps in which olefins are produced during the dewaxing, (ii) separating the effluent from the first of the two catalytic dewaxing steps to produce a lower boiling fraction including olefins and a higher boiling fraction, (iii) passing the higher boiling fraction to the second of the two catalytic dewaxing steps, (iv) hydrotreating the lower boiling fraction to saturate the olefins and (v) passing the hydrotreated lower boiling fraction to the second catalytic dewaxing step.
- 2. A process according to claim 1 in which the feedstock comprises a lube feedstock, the lower boiling fraction comprises a fraction boiling below the lube boiling range and the higher boiling fraction comprises a partly dewaxed fraction in the lube boiling range.
- 3. A process according to claim 2 in which the higher boiling fraction is a 650.degree. F.+ fraction and the lower boiling fraction is a 650.degree. F.- fraction.
- 4. A process according to claim 1 in which the catalytic dewaxing steps are carried out by contract with an intermediate pore size zeolite dewaxing catalyst.
- 5. A process according to claim 4 in which the zeolite is ZSM-5.
- 6. A process according to claim 1 in which the catalytic dewaxing steps are carried out in the presence of hydrogen.
- 7. A process according to claim 6 in which the hydrogen is introduced into the first catalytic dewaxing step with the feedstock with hydrogen from the first catalytic dewaxing step passing to the hydrotreating step from the separation step and from the hydrotreating step to the second catalytic dewaxing step.
- 8. A method according to claim 7 in which effluent from the second catalytic dewaxing step is passed to a subsequent hydrotreating step, including hydrogen from the second catalytic dewaxing step.
- 9. A process according to claim 1 in which the light fraction includes fractions having a boiling range up to 350.degree. F.
- 10. A process according to claim 1 in which the light fraction includes fractions having a boiling range up to 330.degree. F.
- 11. A process for dewaxing a relatively waxy lube oil feedstock having an initial boiling point of at least 610.degree. F., which comprises:
- (i) catalytically dewaxing the feedstock in the presence of hydrogen by contact with an intermediate pore size dewaxing catalyst under dewaxing conditions to produce an effluent including a partly dewaxed product and olefins,
- (ii) separating the effluent to form a partly dewaxed product in the lube boiling range and a lower boiling fraction including olefins,
- (iii) catalytically dewaxing the partly dewaxed product in a second catalytic dewaxing step by contact in the presence of hydrogen with an intermediate pore size dewaxing catalyst,
- (iv) hydrotreating the lower boiling portion of the separated lower boiling fraction in an interstage hydrotreating step to saturate the olefins in that portion and form a hydrotreated effluent,
- (v) passing the hydrotreated effluent to the second catalytic dewaxing step.
- 12. A process according to claim 11 in which the entire separated lower boiling fraction is hydrotreated.
- 13. A process according to claim 11 in which the lower boiling portion of the lower boiling fraction is hydrotreated and the higher boiling portion of the lower boiling fraction is withdrawn from the dewaxing sequence of the catalytic dewaxing steps.
- 14. A process according to claim 11 in which the lower boiling portion comprises the C.sub.6 - fraction.
- 15. A process according to claim 13 in which the lower boiling portion comprises the C.sub.6 - fraction and the higher boiling fraction comprises naphtha and distillate boiling below the lube boiling range.
- 16. A process according to claim 13 in which the higher boiling portion withdrawn from the dewaxing sequence is hydrotreated.
- 17. A process according to claim 16 in which the higher boiling portion withdrawn from the dewaxing sequence is combined with the dewaxed effluent from the second catalytic dewaxing step and the combined fraction subjected to hydrotreating.
- 18. A process according to claim 11 in which the catalytic dewaxing steps are carried out in the presence of hydrogen introduced with the feedstock into the first catalytic dewaxing step, the interstage hydrotreating step being supplied with hydrogen from the first catalytic dewaxing step, the second catalytic dewaxing step being fed with hydrogen from the interstage hydrotreating step.
- 19. A process according to claim 11 in which the intermediate pore size zeolite in the first and second catalytic dewaxing steps is ZSM-5.
- 20. A process according to claim 11 in which the feedstock comprises a 650.degree. F.+ lube feedstock.
- 21. A process for dewaxing a relatively waxy lube oil feedstock having an initial boiling point of at least 610.degree. F., which comprises:
- (i) catalytically dewaxing the feedstock in the presence of hydrogen by contact with an intermediate pore size dewaxing catalyst under dewaxing conditions to produce an effluent including a partly dewaxed product and olefins,
- (ii) separating the effluent to form a partly dewaxed product in the lube boiling range and a lower boiling fraction including olefins,
- (iii) catalytically dewaxing the partly dewaxed product in a second catalytic dewaxing step by contact in the presence of hydrogen with an intermediate pore size dewaxing catalyst,
- (iv) hydrotreating the portion of the lower boiling fraction comprising the majority of the olefins formed in the first catalytic dewaxing step in an interstage hydrotreating step to saturate the olefins, and form a hydrotreating effluent including hydrogen,
- (v) passing the hydrotreated effluent to the second catalytic dewaxing step.
- 22. A process according to claim 21 in which the portion of the lower boiling fraction subjected to the interstage hydrotreating step comprises the fraction boiling below about 330.degree. F.
- 23. A process according to claim 21 in which the portion of the lower boiling fraction subjected to the interstage hydrotreating step comprises the fraction boiling below about 125.degree. F.
- 24. A process according to claim 23 in which the fraction boiling range from about 125.degree. F. to the initial lube boiling point.
- 25. A process according to claim 21 in which the intermediate pore size zeolite comprises ZSM-5.
CROSS REFERENCE TO RELATED APPLICATIONS
This application is a continuation-in-part of copending application Ser. No. 685,564, filed Dec. 24, 1984 U.S. Pat. No. 4,648,957), and Ser. No. 816,092, filed Jan. 3, 1986 U.S. Pat. No. 4,695,364. The disclosures of those two applications are incorporated in this application by reference.
US Referenced Citations (10)
Continuation in Parts (1)
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Number |
Date |
Country |
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685564 |
Dec 1984 |
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