Alkylation process

Details Alkylation process Alkylation process

1997-07-29

2001-01-16

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...

C526S160000, C526S905000, C502S152000, C502S104000

Reexamination Certificate

active

06174972

ABSTRACT:

The present invention relates to a process for polymerization of an olefin such as ethylene in the presence of catalyst systems including a catalyst in the form of an organometallic compound of a transition metal which has at least one ligand of cyclopentadienyl or substituted cyclopentadienyl type.
It is known to polymerize olefins such as ethylene with the aid of a catalyst comprising an organometallic compound of a transition metal from groups IVA, VA or VIA of the Periodic Classification of the elements (IUPAC version in CRC Handbook of Chemistry and Physics, 73rd Edition, CRC Press Inc., 1992-1993) a metal such as titanium, zirconium or hafnium and possessing at least one ligand of cyclopentadienyl or substituted cyclopentadienyl type. In particular, catalysts comprising metallocene complexes such as zirconocenes, titanocenes or hafnocenes, in particular (cyclopentadienyl)
2
ZrCl
2
, are known as catalysts in the polymerization of olefins in the presence of an appropriate cocatalyst. Such catalyst systems have proved their very high activity in the polymerization of ethylene and of alpha-olefins by giving polyolefins of very narrow molecular mass distribution.
It has been observed, however, that the use of hydrogen in polymerization with a catalyst containing an organometallic compound of a transition metal possessing at least one ligand of cyclopentadienyl or substituted cyclopentadienyl type, for example a catalyst comprising a zirconocene, a titanocene or a hafnocene, can in some cases considerably reduce the activity of the catalyst system in the olefin polymerization, until the polymerization reaction is completely blocked.
EP 0 459 320 relates to a process for polymerizing olefin with the help of a metallocene catalyst system in solution or in suspension. Halogenated hydrocarbon solvent can be particularly used as liquid polymerization medium.
EP 0 602 509 relates to a process for polymerizing olefin with the help of a metallocene catalyst system in suspension in a liquid medium selected amongst hydrocarbons or halogenated hydrocarbons.
A process has now been found which allows the abovementioned problems to be solved. In particular, a process has been found for olefin polymerization in the presence of catalyst systems including a catalyst as mentioned above, a process which makes it possible at the same time to maintain a sufficiently high activity in polymerization and to control the molecular mass of the polyolefins especially with the aid of hydrogen.
The subject of the present invention is therefore a process for polymerization of at least one olefin with the aid of a catalyst system including a catalyst containing at least one organometallic compound of a transition metal possessing at least one ligand of cyclopentadienyl or substituted cyclopentadienyl type, characterized in that the polymerization is carried out in gas phase or in suspension in a liquid polymerization medium selected amongst saturated or unsaturated hydrocarbons, in the presence of hydrogen and a polymerization component selected amongst halogenated hydrocarbons.
The halogenated hydrocarbon may include one or more halogen atoms such as fluorine, chlorine or bromine. It contains preferably one or more chlorine atoms. It may correspond to the general formula
in which X denotes a halogen atom such as fluorine, chlorine or bromine and R
1
, R
2
and R
3
, being identical or different, denote a halogen atom such as fluorine, chlorine or bromine, a hydrogen atom, an alkyl radical optionally halogenated containing, for example, from 1 to 7, preferably from 1 to 5 carbon atoms, such as the methyl or ethyl radical, or from 0 to 5, preferably from 0 to 3 halogen atoms such as fluorine, chlorine or bromine, an aryl radical optionally halogenated containing, for example, from 6 to 10, preferably from 6 to 8 carbon atoms, such as the phenyl radical and from 0 to 5, preferably from 0 to 3 halogen atoms such as fluorine, chlorine or bromine, or an aralkyl radical optionally halogenated containing, for example, from 7 to 14, preferably from 7 to 11 carbon atoms, such as the benzyl radical and from 0 to 5, preferably from 0 to 3 halogen atoms such as fluorine, chlorine or bromine.
The halogenated hydrocarbon may be chosen in particular from the group consisting of chloromethane, dichloromethane, chloroform, carbon tetrachloride, dichloromonofluoromethane, dichlorodifluoromethane, 1,2-dichloroethane, 1,1-dichloroethane, 1,1,1-trichloroethane, tert-butyl chloride and benzyl chloride. Chloroform is preferred.
The catalyst system includes a catalyst comprising at least one organometallic compound of a transition metal from Groups IVA, VA or VIA of the Periodic Classification of the Elements, in particular a metal from Group IVA, such as titanium, zirconium or hafnium and possessing at least one ligand of cyclopentadienyl or substituted cyclopentadienyl type.
The catalyst may comprise at the same time an organometallic compound of a transition metal possessing at least one ligand of cyclopentadienyl or substituted cyclopentadienyl type, and a compound of a transition metal identical with or different from the first, not being organometallic and/or not possessing this type of ligand, for example being in the form of a polyhalide or of a polyalcoholate or of a polyhaloalcoholate of a metal from groups IVA or VA, such as titanium, vanadium or zirconium, in particular a titanium or vanadium tetrahalide, a titanium or vanadium trihalomonoalcoholate, a titanium or vanadium dihalodialcoholate, a titanium or vanadium monohalotrialcoholate, a titanium or vanadium tetraalcoholate, a vanadyl trihalide, a vanadyl dihalomonoalcoholate, a vanadyl monohalodialcoholate or a vanadyl trialcoholate.
The catalyst comprises at least one organometallic compound of a transition metal possessing at least one ligand of cyclopentadienyl or substituted cyclopentadienyl type, compound which may preferably correspond to one of the following general formulae:
(C
5
R′
m
)
p
R″
s
(C
5
R′
m
)MeQ
3-p
  (I)
or
R″
s
(C
5
R′
m
)
2
MeQ′  (II)
in which Me denotes an atom of transition metal from groups IVA, VA or VIA, preferably from group IVA, of the Periodic Classification of the Elements, (C
5
R′
m
) denotes a cyclopentadienyl or substituted cyclopentadienyl radical, each R′, being identical or different, denotes a hydrogen atom or an alkyl, alkylene, aryl or aralkyl radical containing, for example, from 1 to 20 carbon atoms, or two substituents R′ together form a condensed ring containing, for example, from 4 to 6 carbon atoms, R″ denotes an alkylene radical containing, for example, from 1 to 4 carbon atoms, a dialkylgermanium or a silicon atom or an alkylphosphine radical or an amine radical joining the two (C
5
R′
m
) rings via a bridge, each Q, being identical or different, denotes an aryl, alkyl, alkylene or aralkyl radical containing, for example, from 1 to 20 carbon atoms or a halogen atom such as chlorine or bromine, Q′ denotes an alkylidene radical containing, for example, from 1 to 20 carbon atoms, s is 0 or 1, p is 1 or 1 or 2; on condition that s is 0 when p is 0; m is 4 when s is 1; m is 5 when s is 0;
or the general formula:
in which Me denotes an atom of transition metal from groups IVA, VA or VIA, preferably from group IVA,, of the Periodic Classification of the Elements, C
p
* denotes a cyclopentadienyl or substituted cyclopentadienyl radical bound in an &eegr;
5
bonded mode to Me, Z denotes a divalent group including boron or an element from group IVB and optionally sulphur or oxygen, the said group containing, for example, not more than 20 nonhydrogen atoms, and optionally C
p
* and Z together form a condensed ring, each X, being identical or different, denotes an anionic ligand or a neutral Lewis base containing, for example, not more than 30 nonhydrogen atoms, n is 0, 1, 2, 3 or 4, depending on the valency of Me, and Y denotes an anionic or non-anionic ligand, bonded to Z and Me, including nitrogen, phosphorus, oxygen or sulphur a

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