Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Reexamination Certificate
2003-01-10
2004-10-05
Harlan, Robert D. (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Polymers from only ethylenic monomers or processes of...
C526S129000, C526S130000, C526S133000, C526S134000, C526S161000, C526S172000, C502S104000, C502S155000, C502S167000, C502S204000
Reexamination Certificate
active
06800702
ABSTRACT:
This invention relates to the trimerisation of olefins, such as the preparation of 1-hexene by the trimerisation of ethylene.
U.S. Pat. No. 5,198,563 and related patents by Phillips describe chromium-containing catalysts containing monodentate amide ligands useful for trimerising olefins.
U.S. Pat. No. 5,968,866 discloses an ethylene oligomerisation/trimerisation process which uses a catalyst comprising a chromium complex which contains a coordinating asymmetric tridentate phosphane, arsane or stibane ligand (referred to therein as phosphine, arsine or stibine, and representing a phosphorus, arsenic or antimony atom attached to three hydrocarbyl groups) and an aluminoxane to produce alpha-olefins which are enriched in 1-hexene. There is no suggestion that it is possible to replace any of the phosphane, arsane or stibane groups: indeed, it is impossible to predict what the effect of such a replacement would be.
We have now discovered further ligands which when used in conjunction with a source of a Group 3 to 10 transition metal are significantly more active as trimerisation catalysts than those currently known, and also show other advantageous properties. The invention also encompasses within its scope novel catalysts comprising such ligands in conjunction with a source of chromium, molybdenum or tungsten.
Accordingly in a first aspect, the present invention provides a catalyst for the trimerisation of olefins, comprising
(a) a source of chromium, molybdenum or tungsten;
(b) a ligand containing at least one phosphorus, arsenic or antimony atom bound to at least one hydrocarbyl or heterohydrocarbyl group having a polar substituent, but excluding the case where all such polar substituents are phosphane, arsane or stibane groups; and optionally
(c) an activator.
In this specification the term “trimerisation” means catalytic reaction of a single olefinic monomer or a mixture of olefinic monomers to give products enriched in those constituents derived from the reaction(s) of three olefinic monomers, as distinct from polymerisation or oligomerisation, which typically give olefinic product distributions governed by either a geometric series equation or following a Poisson pattern of distribution. “Trimerisation” includes the case where all the monomer units in the trimerisation product are identical, where the trimerization product is made from two different olefins (i.e. two equivalents of one monomer react with one equivalent of a second monomer), and also where three different monomer units react to yield the product. A reaction involving more than one monomer is often referred to as cotrimerisation.
It will be appreciated that the above catalyst may either be formed prior to use in a trimerisation reaction, or it may be formed in situ by adding the individual components thereof to the reaction mixture.
In a further aspect, the invention provides a process for the trimerisation of olefins, comprising contacting a monomeric olefin or mixture of olefins under trimerisation conditions with a catalyst which comprises
(a) a source of a Group 3 to 10 transition metal;
(b) a ligand containing at least one phosphorus, arsenic or antimony atom bound to at least one hydrocarbyl or heterohydrocarbyl group having a polar substituent, but excluding the case where all such polar substituents are phosphane, arsane or stibane groups; and optionally
(c) an activator.
We have also found that the catalysts used in the above process have certain novel features. For example, such catalysts when supported lose less of their activity compared with the equivalent unsupported catalyst than known catalysts. A further aspect of the invention therefore is a supported catalyst having a productivity per mole of catalyst of at least 50%, preferably at least 70% of its productivity when unsupported, which catalyst preferably comprises
(a) a source of a Group 3 to 10 transition metal;
(b) a ligand containing at least one phosphorus, arsenic or antimony atom bound to at least one hydrocarbyl or heterohydrocarbyl group having a polar substituent, but excluding the case where all such polar substituents are phosphane, arsane or stibane groups; and optionally
(c) an activator.
Additionally, we have found that such catalysts have unusually high productivity, and maintain that productivity particularly well. Accordingly one further aspect of the invention comprises a catalyst for the trimerisation of olefins, which has a productivity of at least 30000 g product per mmol catalyst per hour at a temperature of 110° C. or less and an ethylene partial pressure of 21 bar or less. Another aspect of the invention is a catalyst for the trimerisation of olefins, wherein the catalyst productivity decays at a rate of less than 10% per hour.
In one embodiment of the process of the invention, the catalyst utilised in the present invention additionally comprises a further catalyst (d) suitable for the polymerisation, oligomerisation or other chemical transformations of olefins. In processes wherein such an additional catalyst is present, the trimerisation products are incorporated into a higher polymer or other chemical product.
The catalysts used in the trimerisation process of the invention show exceptionally high productivity and selectivity to 1-hexene within the product fraction containing 6 carbon atoms. The high productivity of the catalysts results in greater process efficiency and/or lower intrinsic levels of catalyst residues. The high selectivity of the catalysts results in a greater ease of product purification (resulting either in less costly product purification or purer products). These advantages would be expected to apply both to processes wherein catalysts according to the invention comprise the sole catalytic component and also to integrated processes, for example in the production of branched polyolefins, where more than one transition metal catalyst is employed.
As regards the source of Group 3 to 10 transition metal (a), this can include simple inorganic and organic salts, for example, halides, acetylacetonates, carboxylates, oxides, nitrates, sulfates and the like, as well as co-ordination and organometallic complexes, for example, chromium trichloride tetrahydrofuran complex, (benzene)tricarbonylchromium, chromium hexacarbonyl, molybdenum hexacarbonyl and the like. Preferably component (a) is a source of chromium, molybdenum or tungsten; particularly preferred is chromium.
The ligand of component (b) preferably has the formula
(R
1
)(R
2
)X-Y-X(R
3
)(R
4
), wherein
X is phosphorus, arsenic or antimony;
Y is a linking group;
and R
1
, R
2
, R
3
and R
4
are each independently hydrocarbyl, substituted hydrocarbyl, heterohydrocarbyl or substituted beterohydrocarbyl groups, at least one of which has a polar substituent which is not a phosphane, arsane or stibane group.
An alternative preferred structure for the ligand of component (b) is X(R
1
)(R
2
)(R
3
) wherein X and R
1
, R
2
and R
3
are as defined above, with at least one of R
1
, R
2
and R
3
having a polar substituent which is not a phosphane, arsane or stibane group.
X is preferably phosphorus. As regards R
1
, R
2
, R
3
and R
4
, examples of suitable hydrocarbyl groups are methyl, ethyl, ethylenyl, propyl, butyl, cyclohexyl, benzyl, phenyl, tolyl, xylyl, mesityl, biphenyl, naphthyl, anthracenyl and the like. Examples of suitable beterohydrocarbyl groups are methoxy, ethoxy, phenoxy (i.e. —OC
6
H
5
), tolyloxy (i.e. —OC
6
H
4
(CH
3
)), xylyloxy, mesityloxy, dimethylamino, diethylamino, methylethylamino, thiomethyl, thiophenyl, trimethylsilyl, dimethylhydrazyl and the like.
Preferably those of R
1
to R
4
having polar substituents are substituted aryl groups with at least one polar substituent. Suitable substituted aryl groups include substituted phenyl, substituted naphthyl and substituted anthracenyl groups. Substituted phenyl is preferred. Polar substituents include methoxy, ethoxy, isopropoxy, C
3
-C
20
alkoxy, phenoxy, pentafluorophenoxy, trimethylsiloxy, dimethylamino, methylsulphanyl, tosyl, methoxymethyl, methylthiomethyl, 1,3-oxazolyl, met
BP Chemicals Limited
Finnegan, Henderson Farabow, Garrett and Dunner L.L.P.
Harlan Robert D.
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