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
2000-12-26
2004-12-07
La Villa, Michael (Department: 1775)
Catalyst, solid sorbent, or support therefor: product or process
Catalyst or precursor therefor
Plural component system comprising a - group i to iv metal...
C502S113000, C502S132000, C502S150000, C502S169000, C502S171000, C502S226000, C502S306000, C502S340000, C526S089000, C526S123100, C526S124300
Reexamination Certificate
active
06828269
ABSTRACT:
The present invention relates to a process for oligomerizing ethylene, in particular to 1-hexene, and to the catalytic composition used.
Processes for producing alpha olefins from ethylene generally result in a series of oligomers containing 4 to 30 carbon atoms and even more than 30 carbon atoms, and the olefins are then separated by distillation. The demand for lower olefins, essentially 1-butene, 1-hexene and 1-octene, has been increasing over the past few years; they are used in particular as co-monomers with ethylene in the production of linear low density polyethylene.
Only a few catalysts exist that can selectively lead to the formation of a particular oligomer, as is the case when dimerizing ethylene to butene-1 with a titanium-based catalyst. However, chromium-based catalysts are known to result in the principal formation of 1-hexene, with more or less polyethylene, the proportion of butenes and octenes in the products being very low. (R. M. Manyik, W. E. Walker, T. P. Wilson, J. Catal., 1977, 47, 197 and J. R. Briggs, J. Chem. Soc., Chem. Commun. 1989, 674 and cited references). Catalysts for more or less selective ethylene trimerization have been claimed, for example, in U.S. Pat. Nos. 5,198,563, 5,288,823, and 5,382,738, European patent applications Nos. 0 608 447, 0 611 743 and 0 614 865. Such catalysts are prepared from a chromium salt and a metallic amide, in particular a pyrrole. Other catalysts use an aluminoxane and a chromium complex with a chelating phosphine (U.S. Pat. No. 5,550,305).
French patent application 2 764 524 describes a catalytic composition obtained by mixing at least one chromium compound with at least one aluminum aryloxy compound and at least one hydrocarbylaluminum compound, that has a particular selectivity for the formation of butene-1 and/or 1-hexene by ethylene oligomerization.
It has now been discovered that a catalytic composition obtained by mixing at least one chromium compound with at least one aryloxy compound of an element M selected from the group formed by magnesium, calcium, strontium and barium and with at least one hydrocarbylaluminum compound, has a particular selectivity for the formation of 1-hexene by ethylene oligomerization.
More precisely, said catalytic composition is obtained by mixing:
at least one chromium compound that can comprise one or more identical or different anions selected from the group formed by halides, carboxylates, acetylacetonates, alkoxy and aryloxy anions;
with at least one aryloxy compound of an element M selected from the group formed by magnesium, calcium, strontium and barium, with general formula M(RO)
2-n
X
n
, where RO is an aryloxy radical containing 6 to 80 carbon atoms, X is a halogen or a hydrocarbyl radical containing 1 to 30 carbon atoms and n is a whole number that can take values of 0 to 2;
and with at least one aluminum compound selected from hydrocarbylaluminum compounds with general formula AlR′
m
Y
3-m
, where R′ is a hydrocarbyl radical containing 1 to 6 carbon atoms, Y is a chlorine or bromine atom and m is a number from 1 to 3 (i.e., tris(hydrocarbyl)-aluminum compounds, chlorinated or brominated hydrocarbylaluminum compounds) and aluminoxanes.
The chromium compound can be a chromium (II) or chromium (III) salt, but also a salt with a different oxidation number that can comprise one or more identical or different anions such as halides, carboxylates, acetylacetonates or alkoxy or aryloxy anions. The chromium compounds preferably used in the invention are chromium (III) complexes as they are more accessible, but a chromium (I) compound or chromium (II) compound may also be suitable.
The chromium compounds selected can advantageously be dissolved in a hydrocarbon medium by complexing with an organic oxygen-containing compound such as an ether, an ester or a compound selected from acetates and ketals (these latter resulting from condensation of an aldehyde or a ketone with a monoalcohol or a polyalcohol) such as 2,2-di(2-ethylhexyloxy)propane.
The aryloxy compound of element M is selected from the group formed by magnesium, calcium, strontium and barium, with (general formula M(RO)
2-n
X
n
, where RO is an aryloxy radical containing 6 to 80 carbon atoms. X is a halogen (chlorine or bromine) or a linear or branched hydrocarbyl radical containing 1 to 30 carbon atoms, for example alkyl, cycloalkyl, alkenyl, aryl, aralkyl, substituted aryl or substituted cycloalkyl, preferably a hydrocarbyl residue containing 2 to 10 carbon atoms, and n is a whole number that can take values of 0 to 2.
Preferred aryloxy compounds of element M comprise an aryloxy radical RO with general formula:
where R
1
, R
2
, R
3
, R
4
and R
5
, which may be identical or different, each represent a hydrogen atom, a halogen atom or a hydrocarbyl radical, for example alkyl, cycloalkyl, alkenyl, aryl, or aralkyl, substituted aryl or cycloalkyl, preferably containing 1 to 16 carbon atoms, more particularly 1 to 10 carbon atoms. Non limiting examples of R
1
, R
2
, R
3
, R
4
and R
5
are methyl, ethyl, n-propyl, ispropyl, n-butyl, tert-butyl, cyclohexyl, benzyl, phenyl, 2-methylphenyl, 2,6-dimethylphenyl, 2,4,6-trimethlylphenyl, or 2-methyl-2-phenylprop-1-yl residues.
Non-limiting examples of preferred aryloxy radicals that can be cited are: 4-phenylphenoxy, 2-phenylphenoxy, 2,6-diphenylphenoxy, 2,4,6-triphenylphenoxy, 2,3,5,6-tetraphenylphenoxy, 2-tert-butyl-6-phenylphenoxy, 2,4-di-tert-butyl-6-phenylphenoxy, 2,6-diisopropyphenoxy, 2,6-dimethylphenoxy 2,6-di-tert-butylphenoxy, 4-methyl-2,6-di-tert-butylphenoxy, 2,6-dichloro-4-tert-butylphenoxy and 2,6-dibromo-4-tert-butylphenoxy. When the aryloxy compound of element M is selected from aryloxides with general formula M(RO)
2
, the two aryloxy radicals can be carried by the same molecule, for example the biphenoxy radical, the binaphthoxy radical or the 1,8-naphthalene-dioxy radical, which may or may not be substituted by one or more alkyl, aryl or halogen radicals.
The preparation of the compound M(RO)
2-n
X
n
is known in the literature. Any process for preparing this compound is suitable, such as reacting a phenol ROH with a dialkylmetallic element in an organic solvent, for example a hydrocarbon or an ether.
The aluminum compounds used in the invention are selected from hydrocarbylaluminum-tris(hydrocarbyl)aluminum compounds, chlorinated or brominated hydrocarbylaluminum compounds and aluminoxanes. The tris(hydrocarbyl)aluminum compounds and chlorinated or brominated compounds of hydrocarbylaluminum are represented by general formula AlR′
m
Y
3-m
where R′ is a hydrocarbyl radical, preferably alkyl, containing 1 to 6 carbon atoms, Y is a chlorine or bromine atom, preferably a chlorine atom, and m is a number from 1 to 3. Non-limiting examples that can be cited are: dichloroethylaluminum, ethylaluminum sesquichloride, chlorodiethyl-aluminum, chlorodiisobutylaluminum, triethylaluminum, tripropylaluminum, triisobutylaluminum and methylaluminoxane. The preferred hydrocarbylaluminum compound is triethylaluminum.
The catalyst components can be brought into contact in a solvent comprising at least one saturated hydrocarbon such as hexane, cyclohexane, heptane, butane or isobutane, at least one unsaturated hydrocarbon such as a mono-olefin or a diolefin containing 4 to 20 carbon atoms, for example, and/or at least one aromatic hydrocarbon such as benzene, toluene, ortho-xylene, mesitylene or ethylbenzene.
The chromium concentration in the catalytic solution can be in the range 1×10
−5
to 0.1 mole/l, preferably 5×10
−5
to 1×10
−2
mole/l. The mole ratio between the aryloxy compound of element M and the chromium compound can be from 1:1 to 30:1, preferably 1:1 to 20:1. The mole ratio between the hydrocarbylaluminum and the chromium compound is in the range 1:1 to 35:1, preferably 1:1 to 15:1.
The order of mixing the three constituents of the catalytic composition is not critical. However, the chromium compound is preferably mixed first with the aryloxy compound of element M, and then the hydrocarbylaluminum
Commereuc Dominique
Drochon Sebastien
Saussine Lucien
Institut Francais du Pe'trole
La Villa Michael
Millen White Zelano & Branigan P.C.
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