Chemistry of hydrocarbon compounds – Plural serial diverse syntheses – To produce unsaturate
Reexamination Certificate
2001-01-11
2004-03-16
Griffin, Walter D. (Department: 1764)
Chemistry of hydrocarbon compounds
Plural serial diverse syntheses
To produce unsaturate
C585S324000, C585S326000, C585S329000, C585S518000, C585S519000, C585S520000, C585S616000, C208S018000
Reexamination Certificate
active
06706936
ABSTRACT:
The present invention relates to a process for making a lube base stock from materials having lower molecular weights. Included in this invention is a process for making predominately bright stock lube base stock.
BACKGROUND OF THE INVENTION
Lubricant oils of high viscosity and high oxidation stability are desirable. Such materials have been prepared, for example, by hydrocracking, hydrodewaxing and hydrofinishing various petroleum feedstocks and by polymerizing normal alpha olefins such as 1-decene. The former route has the advantage of moderate costs, but the oxidation stability is not exceptional. As attempts are made to improve the oxidation stability by increasing the severity of the hydroprocessing steps, the yield of lube declines, as does its viscosity. The latter route gives an exceptionally stable product, but suffers the disadvantage of high cost.
It would be desirable to provide a moderate cost process that generates high viscosity and highly stable products. The present invention provides such a process.
U.S. Pat. No. 6,025,533 to Vora, et al. (“Oligomer Production with Catalytic Distillation”) teaches production of heavy oligomers (C
7
+oligomers) from C
4
paraffins and olefins by a combination of dehydrogenation and oligomerization. The process has at least one catalyst bed in the top of a distillation column for separating the oligomerization effluent of the dehydrogenation and oligomerization combination.
U.S. Pat. No. 5,276,229 to Buchanan, et al. (“High VI Synthetic Lubricants From Thermally Cracked Slack Wax”) teaches oligomerizing alpha-olefins produced from thermal cracked slack wax.
U.S. Pat. No. 5,015,361 to Anthes, et al. (“Catalytic Dewaxing Process Employing Surface Acidity Deactivated Zeolite Catalysts”) teaches oligomerization of propylene in two stages using ZSM-23 and ZSM-5 to form a low pour point, high cloud point product, followed by dewaxing.
U.S. Pat. No. 4,855,524 to Harandi, et al. (“Process For Combining The Operation of Oligomerization Reactors Containing a Zeolite Oligomerization Catalyst”) teaches combining the operation of a primary reactor that oligomerizes a C
3-7
feed to gasoline range hydrocarbons and a high pressure secondary reactor that oligomerizes the effluent of the first reactor to make distillate or lubes.
U.S. Pat. No. 4,678,645 to Chang, et al. (“Conversion of LPG Hydrocarbons to Distillate Fuels or Lubes Using Integration of LPG Dehydrogenation and MOGDL”) teaches converting C
4
− paraffins to higher hydrocarbons by the combination of catalytic or thermal dehydrogenation of a paraffinic feedstock to produce olefins and conversion of olefins to gasoline and distillate boiling range materials in a low pressure oligomerization catalytic reactor and a high pressure oligomerization catalytic reactor.
A variety of patents disclose catalysts useful for oligomerization.
U.S. Pat. No. 5,453,556 to Chang et al. Oligomerization Process For Producing Synthetic Lubricants”) teaches an oligomerization process using a catalyst having an acidic solid with a Group IVB metal oxide modified with an oxyanion of a Group VIB metal.
U.S. Pat. No. 5,270,273 to Pelrine et al. (“Olefin Oligomerization Catalyst”) teaches an olefin oligomerization catalyst having a supported, reduced Group VIB metal oxide on an inorganic support, such as MCM-41.
U.S. Pat. No. 5,243,112 to Chester, et al. (“Lubricant Range Hydrocarbons From Light Olefins”) teaches oligomerizing an olefinic feedstock over a medium pore zeolite catalyst (HZSM-22).
U.S. Pat. No. 5,171,909 to Sanderson, et al. (“Synthetic Lubricant Base Stocks From Long-Chain Vinylidene Olefins and Long-Chain Alpha- and/or Internal-Olefins”) teaches oligomerization of long-chain olefins using certain acidic montmorillonite clay catalysts.
U.S. Pat. No. 5,146,022 to Buchanan et al (“High VI Synthetic Lubricants From Cracked Slack Wax”) teaches oligomerizing with a Lewis acid catalyst a mixture of C
5
-C
18
or C
6
-C
16
alpha-olefins produced from thermal cracking of slack wax.
U.S. Pat. No. 5,080,878 to Bowes, et al. (“Modified Crystalline Aluminosilicate Zeolite Catalyst and Its Use in the Production of Lubes of High Viscosity Index”) teaches oligomerization with a modified zeolite (ZSM-5, ZSM-11, ZSM-12, ZSM-22, ZSM-23, ZSM-35, ZSM-38, or ZSM-48).
U.S. Pat. No. 4,962,249 to Chen, et al. (“High VI Lubricants From Lower Alkene Oligomers”) teaches oligomerization of lower olefins with a reduced valence state Group VIB metal oxide on porous support. In one embodiment, a feedstock of lower olefins is contacted with surface deactivated, acidic, medium pore, shape selective metallosilicate catalyst under oligomerization conditions, then reacting the mixture with ethylene in contact with an olefin metathesis catalyst under metathesis conditions, then oligomerizing the metathesis product in contact with a reduced valence state Group VIB metal catalyst on porous support.
U.S. Pat. No. 4,542,251 to Miller (“Oligomerization of Liquid Olefin Over a Nickel-Containing Silicaceous Crystalline Molecular Sieve”) teaches oligomerization in the liquid phase using nickel-containing silicaceous crystalline molecular sieve catalysts to produce lube base stock.
U.S. Pat. No. 4,417,088 to Miller (“Oligomerization of Liquid Olefins”) teaches oligomerization of liquid olefins using intermediate pore size molecular sieves to produce lube base stock.
EP 791,643 A1 (“Lubricating Oils”) teaches a process for the production of lubricating oils having a viscosity index of at least 120 and a pour point of −45 C. or less by oligomerizing a feedstock comprising one or more C
5-18
1-olefins in the presence of an oligomerization catalyst comprising an ionic liquid.
In conventional hydrodewaxing, the pour point is lowered by selectively cracking the longer chain wax molecules, mostly normal and slightly branched paraffins. A disadvantage associated with catalytic dewaxing is that the wax is degraded to lower molecular weight materials. For example, waxy paraffins may be cracked down to butane, propane, ethane and methane and so may branched paraffins which do not contribute to the waxy nature of the oil. It is desirable to limit the degree of cracking which takes place during a catalytic dewaxing process, because these lighter products are generally of lower value than the higher molecular weight materials, and because the viscosity index and oxidation stability of the resulting oil is degraded by the loss of paraffins.
A major breakthrough came with the discovery of new dewaxing catalysts, which were found to isomerize rather than crack the wax molecules. Isomerization alters the molecular structure of wax molecules, and generally decreases the pour point of a molecule without significantly changing its boiling point. In contrast to wax cracking, isomerized molecules are retained in the lubricating oil base stock, increasing yield of lubricating oil base stock without reducing viscosity index or oxidation stability significantly.
U.S. Pat. No. 5,135,638 to Miller (“Wax Isomerization Using Catalyst of Specific Pore Geometry”) discloses a process for producing lube oil from a feedstock having greater than 50% wax. The feedstock is isomerized over a catalyst comprising a molecular sieve (e.g., SAPO-11, SAPO-31, SAPO-41, ZSM-22, ZSM-23, and ZSM-35) and at least one Group VIII metal at a pressure of from about 15 psig to about 2000 psig.
U.S. Pat. No. 5,246,566 to Miller (“Wax Isomerization Using Catalyst of Specific Pore Geometry”) discloses a process similar to that of U.S. Pat. No. 5,135,638, but where the waxy feed has a pour point of above about 0 C. and contains greater than about 70% paraffinic carbon.
U.S. Pat. No. 5,282,958 to Santilli, et al. (“Use of Modified 5-7 Å Molecular Sieves For Isomerization of Hydrocarbons”) discloses isomerizing a feed including straight chain and slightly branched chain paraffins having 10 or more carbons using an intermediate pore size molecular sieve (e.g., SAPO-11, SAPO-31, SAPO-41, ZSM-22, ZSM-23, and ZSM-35). Feeds that may be processed by this method include waxy feeds,
Harris Thomas V.
Krug Russell R.
Lok Brent K.
Miller Stephen J.
O'Rear Dennis J.
Chevron U.S.A. Inc.
Griffin Walter D.
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