Catalyst – solid sorbent – or support therefor: product or process – Catalyst or precursor therefor – Plural component system comprising a - group i to iv metal...
Reexamination Certificate
1997-12-19
2001-03-06
Bell, Mark L. (Department: 1755)
Catalyst, solid sorbent, or support therefor: product or process
Catalyst or precursor therefor
Plural component system comprising a - group i to iv metal...
C502S156000, C502S169000, C502S104000
Reexamination Certificate
active
06197713
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to the use of certain Lewis acids to breakdown rare earth containing hydrocarbon solutions having high viscosities into low viscosity solutions.
BACKGROUND OF THE INVENTION
It is well known to use catalysts containing a rare earth element for polymerization of a conjugated diene. Polymerization of butadiene by use of rare earth complexes such as neodymium naphthenate has been reported in the “Journal Polymer Science”, Vol. 18, 3345 (1980). However, other work in this area is disclosed in U.S. Pat. Nos. 4,242,232 to Sylvester et al, 4,696,984 to Carbonaro et al, and 5,360,898 to Jordaan et al, displaying that neodymium naphthenate can be very difficult to dissolve in a hydrocarbon solvent and produces a gel. Such gels require the use of a relatively large amount of quantities of various viscosity reducing additives, generally in an amount exceeding two moles of additive per each mole of rare earth complex. In said literature reference, polymerization of butadiene is displayed using a ternary catalyst consisting of NdCl
3
, an alcohol and Al(C
2
H
5
)
3
. However, when a catalyst system consisting of this combination is used for polymerization many problems arise because NdCl
3
is solid and insoluble in a hydrocarbon solvent and the resulting catalyst component is heterogeneous. Heterogeneous catalysts are disadvantageous for use in industrial operations. Furthermore, catalyst systems consisting of the combination described above have defects, for example, low polymerization activity.
Additionally, such catalysts when treated with viscosity reducing additives are disadvantageous for industrial use for a variety of other reasons. For example, the use of ethers can reduce the stereospecificity of the catalyst. The use of trialkylaluminum compounds can cause the molecular weight distribution to broaden and its molecular weight to decrease. The use of protic viscosity reducing agents can result in the need for more cocatalyst in some polymerizations, thereby raising the cost of catalyst. Finally, the introduction of certain types of viscosity reducing additives can complicate other types of polymerizations if the additives become incorporated into the facilities solvent stream.
The object of this invention is to overcome these disadvantages and to eliminate or reduce the high viscosities occurring upon the mixture of a rare earth complex in a hydrocarbon solvent.
SUMMARY OF THE INVENTION
The present invention relates to a process for the preparation of a non-viscous hydrocarbon solution containing a lanthanide rare earth series compound by dissolving a lanthanide compound in an inert hydrocarbon solvent with a Lewis acid, the Lewis acid being present in an amount sufficient to prevent gel-like formation of highly viscous solutions of the Ln compound when the lanthanum compound is dissolved in the inert hydrocarbon. The Lewis acid is preferably an organometallic halide of a metal in the main group 2, 12, 13 and 14 groups of the Periodic System or a halide of an element of main groups 2, 12, 13, 14 and 15 groups or a transition metal of the Periodic System. Hydrocarbon soluble Lewis acids are the most preferred. The present invention also relates to the non-viscous lanthanide solutions formed by the process.
DESCRIPTION OF THE INVENTION
According to this invention, there is provided a process for reducing the viscosity of a gel-like solution containing a lanthanide rare earth compound by contacting the gel-like solution with a Lewis acid thereby eliminating or reducing the high viscosities. This invention also provides a process for the preparation of a non-viscous solution during the direct synthesis of a lanthanide rare earth series compound in an inert solvent by the addition of a Lewis acid in an amount sufficient to prevent formation of a highly viscous Ln compound and to form a solution having a Brookfield viscosity of less than 1000 centipoise (cps) after treatment with the Lewis acid. The lanthanide rare earth solutions to be treated in accordance with the process of the present invention are normally used in the polymerization of conjugated dienes, and form highly viscous solutions when added to solvents, such as aliphatic hydrocarbons, cycloaliphatic hydrocarbons and aromatic hydrocarbons, preferably hexane. The lanthanide rare earth compounds to be treated are any complexes of a metal belonging to the series of the lanthanides having an atomic number of 57 to 71, in which a ligand is directly bound to the metal and is a monovalent and monodentate organic radical including but not limited to: (—R
1
CO
2
), (—OR
1
), (—NR
1
R
2
) , (—SR
1
), (—OPO(OR
2
), (—OSO
2
(R)) and (—PR
1
R
2
) wherein R, R
1
and R
2
are independently selected from alkyl, cycloalkyl and aryl hydrocarbon substituents having 1 to 20 carbon atoms. Suitable lanthanum rare earth compounds to be treated are represented by the following structures: Ln(R
1
CO
2
)
3
, Ln(OR
1
)
3
, Ln(NR
1
R
2
)
3
, Ln(SR
1
)
3
, Ln(—OPO(OR)
2
)
3
, Ln(—OSO
2
(R))
3
and Ln(PR
1
R
2
)
3
wherein Ln is a rare earth element in the lanthanide series having an atomic number of 57 to 71 and R, R
1
and R
2
are independently selected from alkyl, cycloalkyl and aryl hydrocarbon substituents having 1 to 20 carbon atoms.
Ln is a rare earth element in the lanthanide series having an atomic number of 57 to 71; lanthanum, cerium, praseodymium, neodymium and gadolinium are preferred, and neodymium is particularly preferable. The Ln may be a mixture of two or more rare earth elements.
The following are typical examples of rare earth compounds that form highly viscous solutions upon addition to certain solvents or upon preparation in solvents: lanthanum tris[bis(2-ethylhexyl)phosphate] and neodymium tris(2-ethyl hexanoate).
The Lewis acids used to reduce the viscosity of the gel-like rare earth compound solutions, are metal halides including transition metal halides such as TiCl
4
, VCl
3
, and the like; and organometallic halides in which the metal atom belongs to the 2, 12, 13 and 14 groups of the Periodic System as well as halides of the elements of 2, 12, 13, 14 and 15 groups of the Periodic System.
methyl aluminum dichloride,
methyl aluminum dibromide,
ethyl aluminum dichloride,
butyl aluminum dibromide,
butyl aluminum dichloride,
dimethyl aluminum bromide,
dimethyl aluminum chloride,
diethyl aluminum bromide,
diethyl aluminum chloride,
dibutyl aluminum bromide,
dibutyl aluminum chloride,
methyl aluminum sesquibromide,
methyl aluminum sesquichloride,
ethyl aluminum sesquibromide,
ethyl aluminum sesquichloride,
dibutyl tin dichloride,
aluminum tribromide,
antimony trichloride,
antimony pentachloride,
phosphorus trichloride,
phosphorus pentachloride
boron tribromide
zinc dichloride
magnesium dichloride
magnesium dibromide.n Et
2
O and
tin tetrachloride.
The following are preferred Lewis acids for use in preventing gel formation in the solution: zinc dichloride, boron tribromide, tin tetrachloride and hydrocarbon soluble metal halides.
A solution of a gel-free Ln compound may be prepared by swelling/dissolving the Ln compound in an inert solvent and then adding the Lewis acid. Aliphatic, cycloaliphatic and aromatic solvents are suitable for this purpose, including but not limited to: pentane, hexane, heptane, cyclohexane, benzene, and toluene. The quantity of Lewis acid, used in eliminating or reducing the high viscosities normally occurring in a Ln compound in a hydrocarbon solvent, may vary within wide limits. The molar ratio of Lewis acid to Ln is preferably in the range of from 0.005:1 to 5:1, most preferably from 0.05:1 to 0.5:1 and is generally sufficient to prevent gel formation in the Ln solution from which a catalyst may be derived, the advantageous properties of the resulting catalyst being in no way reduced. In accordance with the present invention the viscosity of the viscous solution of Ln compound in a hydrocarbon solvent to be treated or in an untreated state is at least 1000 centipoise. After treatment with a Lewis acid, the Ln compound in a hydrocarbon solv
Bell Mark L.
Bridgestone Corporation
Burleson David G.
Fry Jude
Pasterczyk J.
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