Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Reexamination Certificate
1999-12-29
2002-09-24
Wu, David W. (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Polymers from only ethylenic monomers or processes of...
C526S169000, C526S124100, C526S124200, C526S124900, C526S172000, C502S123000, C502S167000
Reexamination Certificate
active
06455648
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to olefin production.
Olefins, primarily alpha-olefins, have many uses. For example, alpha-olefins, such as 1-hexene, can be used in hydroformulation (OXO processes). In addition to uses as specific chemicals, alpha-olefins also can be used in polymerization processes as either a monomer or comonomer to prepare polyolefins, or polymers. Several methods of producing olefins are known in the art. These processes include catalyzed dimerization and trimerization processes. Usually, these olefin production processes are exothermic reactions and can generate significant amounts of heat.
Furthermore, preparation of dimerization and trimerization catalyst systems are exothermic reactions and heat needs to be removed from the process. Heat removal requires additional, often expensive, equipment and heat can be detrimental to the activity, productivity and selectivity of the resultant catalyst system. Prior patents have taught in-situ catalyst system preparation, wherein the catalyst system is prepared in-situ in a trimerization reactor. For example, see U.S. Pat. No. 5,198,563 and U.S. Pat. No. 5,288,823.
SUMMARY OF THE INVENTION
Accordingly, it is an object of this invention to provide an improved olefin production processes.
It is a further object of this invention to provide improved olefin oligomerization and trimerization processes.
It is yet another object of this invention to provide an improved heat control of the catalyst system preparation process.
It is still a further object of this invention to provide a more efficient catalyst system production process.
It is another object of this invention to provide a continuous process to prepare an olefin trimerization catalyst system.
In accordance with this invention, a process is provided which comprises preparing an olefin oligomerization or trimerization catalyst system and producing olefins in the presence of the olefin oligomerization or trimerization catalyst system and a solvent, wherein said catalyst system preparation comprises the steps of first contacting a chromium source and a pyrrole-containing compound to form a chromium/pyrrole mixture; second, contacting said chromium/pyrrole mixture with a metal alkyl to form a catalyst system; and then contacting said catalyst system with an alpha-olefin, preferably ethylene.
In accordance with another embodiment of this invention, a process is provided which comprises preparing an olefin oligomerization or trimerization catalyst system and producing olefins in the presence of the olefin oligomerization or trimerization catalyst system and a solvent, wherein said catalyst system preparation comprises the steps of first contacting a metal alkyl and a pyrrole-containing compound to form a metal alkyl/pyrrole mixture; second, contacting said metal alkyl/pyrrole mixture with a chromium source to form a catalyst system; and then contacting said catalyst system with an alpha-olefin, preferably ethylene.
In accordance with yet another embodiment of this invention, a process is provided which consists essentially of preparing an olefin oligomerization or trimerization catalyst system and producing olefins in the presence of the olefin oligomerization or trimerization catalyst system and a solvent, wherein said catalyst system preparation comprises the steps of first contacting a chromium source and a pyrrole-containing compound to form a chromium/pyrrole mixture; second, contacting said chromium/pyrrole mixture with a metal alkyl to form a catalyst system; and then contacting said catalyst system with an alpha-olefin, preferably ethylene.
In accordance with still another embodiment of this invention, a process is provided which consists essentially of preparing an olefin oligomerization or trimerization catalyst system and producing olefins in the presence of the olefin oligomerization or trimerization catalyst system and a solvent, wherein said catalyst system preparation comprises the steps of first contacting a metal alkyl and a pyrrole-containing compound to form a metal alkyl/pyrrole mixture; second, contacting said metal alkyl/pyrrole mixture with a chromium source to form a catalyst system; and then contacting said catalyst system with an alpha-olefin, preferably ethylene.
DETAILED DESCRIPTION OF THE INVENTION
Catalyst Systems
Catalyst systems useful in accordance with this invention comprise a chromium source, a pyrrole-containing compound and a metal alkyl, all of which have been contacted and/or reacted in the presence of an unsaturated hydrocarbon. Optionally, these catalyst systems can be supported on an inorganic oxide support. These catalyst systems are especially useful for the oligomerization of olefins, such as, for example, ethylene to 1-hexene. As used in this disclosure, the term “oligomerization” broadly encompasses the combination of two olefins (dimerization) to form an olefinic product, combination of three olefins (trimerization) to form an olefinic product and combination of more than three olefins to form an olefinic product, but does not include polymerization of olefins. An oligomer can be defined as a compound made up of repeating units, whose properties can change with the addition or removal of one or a few repeating units. The properties of a polymer do not change markedly with such a modification.
The chromium source can be one or more organic or inorganic chromium compounds, wherein the chromium oxidation state is from 0 to 6. If the chromium oxidation state is 0, metallic chromium can be the chromium source. Generally, the chromium source can have a formula of CrX
n
, wherein X can be the same or different and can be any organic or inorganic radical, and n is an integer from 1 to 6. Exemplary organic radicals can have from about 1 to about 20 carbon atoms per radical, and are selected from the group consisting of alkyl, alkoxy, carboxy, ester, ketone, and/or amido radicals. The organic radicals can be straight-chained or branched, cyclic or acyclic, aromatic or aliphatic, can be made of mixed aliphatic, aromatic, and/or cycloaliphatic groups. Exemplary inorganic radicals include, but are not limited to halides, sulfates, and/or oxides.
Preferably, the chromium source is a chromium(II)-containing and/or a chromium(III)-containing compound which can yield a catalyst system with improved oligomerization and/or trimerization activity. Most preferably, the chromium source is a chromium(III) compound because of ease of use, availability, and enhanced catalyst system activity. Exemplary chromium(III) compounds include, but are not limited to, chromium carboxylates, chromium naphthenates, chromium halides, chromium pyrrolides, and/or chromium dionates. Specific exemplary chromium(III) compounds include, but are not limited to, chromium(III) 2,2,6,6,-tetramethylheptanedionate [Cr(TMHD)
3
], chromium(III) 2-ethylhexanoate also called chromium(III) tris(2-ethylhexanoate) [Cr(EH)
3
], chromium(III) naphthenate [Cr(Np)
3
], chromium(III) chloride, chromic bromide, chromic fluoride, chromium(III) acetylacetonate, chromium(III) acetate, chromium(III) butyrate, chromium(III) neopentanoate, chromium(III) laurate, chromium(III) stearate, chromium(III) pyrrolides and/or chromium(III) oxalate.
Specific exemplary chromium(II) compounds include, but are not limited to, chromous bromide, chromous fluoride, chromous chloride, chromium(II) bis(2-ethylhexanoate), chromium(II) acetate, chromium(II) butyrate, chromium(II) neopentanoate, chromium(II) laurate, chromium(II) stearate, chromium(II) oxalate and/or chromium(II) pyrrolides.
The pyrrole-containing compound can be any pyrrole-containing compound that will react with the chromium source to form a chromium pyrrolide complex. As used in this disclosure; the term “pyrrole-containing compound” refers to hydrogen pyrrolide, i.e., pyrrole (C
4
H
5
N), derivatives of hydrogen pyrrolide, substituted pyrrolides, as well as metal pyrrolide complexes. A “pyrrolide”, as used in this disclosure, is defined as a compound comprising a 5-membered, nitrogen-co
Cowan Glyndal D.
Ewert Warren M.
Freeman Jeffrey W.
Knudsen Ronald D.
Kreischer Bruce E.
Lu Caixia
Wu David W.
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