US 4,357,232 AGranted

Method for enhancing catalytic activity

AssigneeMobil Oil Corporation

InventorsRobert E. Holland, Samuel A. Tabak

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Abstract

Catalytically dewaxed lubricating base stock oils that have improved resistance to oxidation are produced by pretreating the waxy furfural raffinate with a zeolite sorbent prior to dewaxing with a zeolite catalyst such as ZSM-5, and conducting the dewaxing at a reduced temperature not to exceed about 675.degree.-700.degree. F.

Claims8

Dependent claims

In a process for preparing a high quality lube base stock oil having a predetermined pour point in the range of about -25.degree. to +30.degree. F. from waxy crude oil, which process comprises:

extracting a distillate fraction that boils within the range of 450.degree. to 1100.degree. F. or a deasphalted short residuum fraction of said waxy crude with a solvent selective for aromatic hydrocarbons to yield a raffinate from which undesirable compounds have been removed;
contacting the raffinate and hydrogen gas with a dewaxing catalyst under dewaxing conditions effective to impart said predetermined pour point, said catalyst comprising a first crystalline zeolite having a dry crystal framework density of not less than about 1.6 grams per cubic centimeter and a constraint index of about 1 to about 12, thereby converting wax contained in the raffinate to lower boiling hydrocarbons;
and,
topping the dewaxed raffinate to remove therefrom components of a low molecular weight;
the improvement, whereby the resistance to oxidation of said dewaxed raffinate is increased, which comprises:
pretreating said raffinate, prior to dewaxing, with a sorbent comprising a second crystalline zeolite having an effective pore diameter equal to or larger than said first crystalline zeolite, said pretreating being conducted under a combination of conditions selected from a temperature of about 35.degree. to about 350.degree. F., a pressure of 0 to 3000 psig, and a contact time equivalent to a LHSV of 0.1 to 100 hr..sup.-1, said combination being effective to provide a pretreated raffinate characterized by an initial equilibrium temperature not exceeding about 675.degree. to 700.degree. F. and at least 25.degree. F. lower than that obtained with said raffinate without pretreatment when dewaxed at about 1 LHSV;
and dewaxing said raffinate at a temperature not to exceed the lesser of said equilibrium temperature of said raffinate without pretreatment minus 25.degree. F., or 700.degree. F.

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Dependencies are inferred from the claim text.

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Abstract

In a process for preparing a high quality lube base stock oil having a predetermined pour point in the range of about -25.degree. to +30.degree. F. from waxy crude oil, which process comprises:

extracting a distillate fraction that boils within the range of 450.degree. to 1100.degree. F. or a deasphalted short residuum fraction of said waxy crude with a solvent selective for aromatic hydrocarbons to yield a raffinate from which undesirable compounds have been removed;
contacting the raffinate and hydrogen gas with a dewaxing catalyst under dewaxing conditions effective to impart said predetermined pour point, said catalyst comprising a first crystalline zeolite having a dry crystal framework density of not less than about 1.6 grams per cubic centimeter and a constraint index of about 1 to about 12, thereby converting wax contained in the raffinate to lower boiling hydrocarbons;
and,
topping the dewaxed raffinate to remove therefrom components of a low molecular weight;
the improvement, whereby the resistance to oxidation of said dewaxed raffinate is increased, which comprises:
pretreating said raffinate, prior to dewaxing, with a sorbent comprising a second crystalline zeolite having an effective pore diameter equal to or larger than said first crystalline zeolite, said pretreating being conducted under a combination of conditions selected from a temperature of about 35.degree. to about 350.degree. F., a pressure of 0 to 3000 psig, and a contact time equivalent to a LHSV of 0.1 to 100 hr..sup.-1, said combination being effective to provide a pretreated raffinate characterized by an initial equilibrium temperature not exceeding about 675.degree. to 700.degree. F. and at least 25.degree. F. lower than that obtained with said raffinate without pretreatment when dewaxed at about 1 LHSV;
and dewaxing said raffinate at a temperature not to exceed the lesser of said equilibrium temperature of said raffinate without pretreatment minus 25.degree. F., or 700.degree. F.

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