Preformed catalytic system comprising a rare-earth metallocene
View Patent ↗A catalytic system based at least on a preformation monomer which is ethylene or a mixture of ethylene and of a conjugated diene, on a metallocene of formula {P(Cp 1 )(Cp 2 )Y} or Cp 3 Cp 4 Y and on an organometallic compound as cocatalyst, Y denoting a group comprising a metal atom which is a rare earth metal, the Cp 1 , Cp 2 , Cp 3 and Cp 4 groups, which are identical or different, being selected from the group consisting of fluorenyl groups, cyclopentadienyl groups and indenyl groups, the groups being substituted or unsubstituted, and P being a group bridging the two Cp 1 and Cp 2 groups and comprising a silicon or carbon atom, is provided. Such a catalytic system exhibits an improved stability of the catalytic activity over time, in particular on storage.
1. A catalytic composition comprising at least:
a preformation monomer which is ethylene or a mixture of ethylene and of a conjugated diene,
an organometallic compound as cocatalyst, and
a metallocene of formula (Ia) or (Ib):
{P(Cp 1 )(Cp 2 )Y} (Ia)
Cp 3 Cp 4 Y (Ib)
Y denoting a group comprising Met-G, with Met denoting a rare earth metal and G denoting a group comprising the borohydride BH 4 unit or denoting a halogen atom X selected from the group consisting of chlorine, fluorine, bromine and iodine,
Cp 1 , Cp 2 , Cp 3 and Cp 4 , which are identical or different, being selected from the group consisting of fluorenyl groups, cyclopentadienyl groups and indenyl groups, the groups being substituted or unsubstituted, and
P being a group bridging the two Cp 1 and Cp 2 groups and comprising a silicon or carbon atom.
2. A catalytic composition according to claim 1 , wherein the cocatalyst is an organomagnesium compound.
3. A catalytic composition according to claim 1 , wherein the cocatalyst is an organometallic compound comprising an alkyl group bonded to the metal atom.
4. A catalytic composition according to claim 1 , wherein the cocatalyst is a dialkylmagnesium compound or an alkylmagnesium halide.
5. A catalytic composition according to claim 1 , in wherein Cp 1 and Cp 2 are identical and are selected from the group consisting of substituted fluorenyl groups and the unsubstituted fluorenyl group of formula C 13 H 8 .
6. A catalytic composition according to claim 1 , wherein Cp 1 and Cp 2 each represent an unsubstituted fluorenyl group of formula C 13 H 8 .
7. A catalytic composition according to claim 1 , wherein G denotes chlorine or the group of formula (II): (BH 4 ) (1+y) -L y -N x (II),
wherein: L represents an alkali metal selected from the group consisting of lithium, sodium and potassium, N represents a molecule of an ether, x is equal to or greater than 0, and y is an integer equal to or greater than 0.
8. A catalytic composition according to claim 1 , wherein the rare earth metal is a lanthanide, the atomic number of which varies from 57 to 71.
9. A catalytic composition according to claim 1 , wherein the rare earth metal is neodymium Nd.
10. A catalytic composition according to claim 1 , wherein the bridge P corresponds to the formula ZR 1 R 2 , Z representing a silicon or carbon atom and R 1 and R 2 , which are identical or different, each representing an alkyl group comprising from 1 to 20 carbon atoms.
11. A catalytic composition according to claim 10 , wherein Z is Si.
12. A catalytic composition according to claim 1 , wherein the metallocene is the (dimethylsilyl)bisfluorenylneodymium borohydride of formula (III): [Me 2 Si(Flu) 2 Nd(μ-BH 4 ) 2 Li(THF)] (III) Flu representing the C 13 H 18 group.
13. A catalytic composition according to claim 1 , wherein the conjugated diene is a 1,3-diene.
14. A catalytic composition according to claim 13 , wherein the conjugated diene is 1,3-butadiene or isoprene.
15. A catalytic composition according to claim 1 , wherein the molar ratio of the preformation monomer to the metal of the metallocene has a value ranging from 5 to 1000.
16. A catalytic composition according to claim 1 , wherein the molar ratio of cocatalyst to the metal of the metallocene has a value ranging from 0.5 to 20.
17. A catalytic composition according to claim 1 , which catalytic composition comprises a hydrocarbon solvent.
18. A catalytic composition according to claim 17 , wherein the hydrocarbon solvent is aromatic or aliphatic.
19. A catalytic composition according to claim 17 , wherein the molar concentration of metal of the metallocene in the catalytic solution has a value ranging from 0.0001 to 0.05 mol/l.
20. A catalytic composition according to claim 1 , wherein the metallocene is of formula (Ia).
21. A process for the preparation of a catalytic composition defined in claim 1 , which comprises the following stages:
a) reacting, in a hydrocarbon solvent, the cocatalyst and the metallocene, and
b) reacting the preformation monomer with the reaction product from stage a).
22. A process according to claim 21 , wherein stage a) takes place at a temperature ranging from 20° C. to 80° C. and stage b) is carried out at a temperature ranging from 40° C. to 120° C.
23. A process for the preparation of a polymer which comprises the polymerization of a monomer M in the presence of a catalytic composition defined in claim 1 , in which the monomer M is selected from the group of the monomers consisting of conjugated dienes, ethylene, α-olefins and their mixtures.
24. A process according to claim 23 , wherein the monomer M is at least one of a 1,3-diene and isoprene.
25. A process according to claim 23 , wherein the monomer M is 1,3-butadiene or a mixture of 1,3-butadiene and ethylene.
26. A process according to claim 23 , wherein the polymer is an elastomer.