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
2000-11-01
2002-12-10
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...
C502S132000, C502S167000, C502S107000
Reexamination Certificate
active
06492293
ABSTRACT:
The present invention relates to a novel catalysts for the polymerisation and copolymerisation of 1-olefins.
The use of certain transition metal compounds to polymerise 1-olefins, for example, ethylene or propylene, is well established in the prior art. The use of Ziegler-Natta catalysts, for example, those catalysts produced by activating titanium halides with organometallic compounds such as triethylaluminium, is fundamental to many commercial processes for manufacturing polyolefins. Over the last twenty or thirty years, advances in the technology have led to the development of Ziegler-Natta catalysts which have such high activities that olefin polymers and copolymers containing very low concentrations of residual catalyst can be produced directly in commercial polymerisation processes. The quantities of residual catalyst remaining in the produced polymer are so small as to render unnecessary their separation and removal for most commercial applications. Such processes can be operated by polymerising the monomers in the gas phase, or in solution or in suspension in a liquid hydrocarbon diluent. Polymerisation of the monomers can be carried out in the gas phase (the “gas phase process”), for example by fluidising under polymerisation conditions a bed comprising the target polyolefin powder and particles of the desired catalyst using a fluidising gas stream comprising the gaseous monomer.
Our own WO99/12981 discloses that 1-olefins may be polymerised by contacting it with certain transition metal, particularly iron, complexes of selected 2,6-pyridinecarboxaldehydebis(imines) and 2,6-diacylpyridinebis(imines). Catalyst supports such as silica, alumina and zirconia are disclosed.
We have discovered that when late transition metal complexes are supported on silica impregnated with titanium or aluminium, improvements in both the polymerisation process and the polymer product may be obtained.
Accordingly, the present invention provides a catalyst for the polymerisation and copolymerisation of 1-olefins, comprising
1) a late transition metal complex,
2) optionally an activating quantity of an activator compound, and
3) a support which has been impregnated with titanium or aluminium, and calcined at a temperature of between 200° C. and 1000° C., said calcining being after impregnation in the case of aluminium.
By “late transition metal” is meant a metal from Groups VIIIb or Ib (Groups 8-11) of the Periodic Table. In particular the metals Fe, Co, Ni, Ru, Rh, Pd, Os, Ir, and Pt are preferred, especially Fe, Co and Ni.
Preferably the support comprises silica, alumina, zirconia, talc, kieselguhr or magnesia.
Preferably the activator is selected from organoaluminium compounds and hydrocarbylboron compounds.
It is preferred that the titanium incorporated into the support is selected from compounds represented by the formulae (a) (R′)
n
Ti(OR′)
m
; (b) (RO)
m
Ti(OR′)
n
; (c) TiX
4
; (d) TiO
2
; (e) titanium acetylacetone compounds and (f) alkanolamine titanates wherein m is 1,2,3 or 4; n is 0,1,2 or 3; m+n=4; the R group is selected from alkyl, aryl, cycloalkyl, and combinations thereof, for example arylalkyl and alkaryl, each group R having 1 to 12 carbon atoms; R′ is selected from the group consisting of R, cyclopentadienyl and alkenyl, for example ethenyl, propenyl, and isopropenyl each group R′ having 1 to 12 carbon atoms; X is halogen, preferably chlorine when more than one R (or R′) group occurs in the titanium compound the groups can be the same or different. The titanium acetylacetonate compound can be, for example, titanium triacetylacetonate, titanium dichlorodiacetylacetonate or titanium dichlorodi(isopropoxide). Titanium compounds represented by the formula (RO)
4
Ti are preferred, particularly the alkyl compounds having from 1 to 6 carbon atoms in each alkyl group for example, titanium tetramethoxide, titanium tetraethoxide, titanium tetraisopropoxide, titanium tetrabutoxide.
It is preferred that the aluminium impregnated into the support silica is selected from compounds represented by the formulae (a) (R′)
n
Al(OR′)
m
; (b) (RO)
m
Al(OR′)
n
; (c) (R′)
n
Al(X)
m
; (d) Al
2
O
3
; (e) aluminium acetylacetonate compounds and (f) alkanolamine aluminates wherein m is 0,1,2 or 3; n is 0,1,2 or 3; m+n=3; the R group is selected from alkyl, aryl, cycloalkyl, and combinations thereof, for example arylalkyl and alkaryl, each group R having 1 to 12 carbon atoms; R′ is selected from the group consisting of R, cyclopentadienyl and alkenyl, for example ethenyl, propenyl, and isopropenyl each group R′ having 1 to 12 carbon atoms; X is halogen preferably chlorine; when more than one R (or R′) group occurs in the aluminium compound the groups can be the same or different. The aluminium acetylacetonate compound can be, for example, aluminium acetylacetonate diisopropoxide, aluminium dichloro acetylacetonate. The alkanolarine aluminate can be for example triethanolamine aluminate. Aluminium compounds represented by the formula R
3
Al are preferred, particularly the alkyl compounds having from 1 to 6 carbon atoms in each alkyl group for example trimethyl aluminium, triethyl aluminium and triisobutyl aluminium.
A further aspect of the present invention is a process for the preparation of a supported catalyst, comprising the steps of:
preparing a support, including the steps of adding to the fluidised support a titanium or aluminium compound, preferably as defined above, and then calcining the resulting titanium- or aluminium-treated support at a temperature of between 200 and 1000° C.;
and then adding to the support a late transition metal complex and optionally an activating quantity of an activator compound.
The invention also comprises in another aspect the use of titanium or aluminium impregnation to improve the activity of a late transition metal olefin polymerisation catalyst.
The invention also comprises in another aspect the use of titanium or aluminium impregnation to alter the melt index ratio or molecular weight distribution in a polymer formed using as catalyst a late transition metal olefin complex.
Preferably the amount of titanium incorporated in the support is from 0.1 to 5 wt %, more preferably from 3 to 4.5 wt %. Preferably the amount of aluminium impregnated in the silica is from 0.1 to 10 wt %, more preferably from 1 to 6 wt %, and most preferably from 1.5 to 2.5 wt %.
Generally the calcining temperature is most conveniently between 200° C. and the sintering temperature of the support; preferably between 300 and 850° C., and more preferably between 400 and 750° C. It is preferred that this calcination takes place under a flow of a dry gas containing a minimum of 1% (v/v) of oxygen. Dry air is often used.
Preferably the support is additionally calcined at a temperature of between 250° C. and the sintering temperature of the support before the titanium or aluminium is impregnated into the support (as well as after this impregnation).
If desired the supported catalysts of the invention can be formed in situ in the presence of the support material, or the support material (having been treated with the titanium or aluminium compound) can be pre-impregnated or premixed, simultaneously or sequentially, with one or more of the catalyst components. For example, formation of the supported catalyst can be achieved by treating the complex of Formula (I) with the activator (2) (when present) in a suitable inert diluent, for example a volatile hydrocarbon, slurrying the titanium-impregnated support with the product and evaporating the volatile diluent. The produced supported catalyst is preferably in the form of a free-flowing powder. The quantity of support employed can vary widely, for example from 100,000 to 1 grams per gram of late transition metal metal present.
The late transition metal complex may comprise bidentate or tridentate ligands, preferably coordinated to the metal through nitrogen atoms. As examples are those complexes disclosed in WO 96/23010.
Preferably the late transitio
Bell Mark L.
BP Chemicals Limited
Finnegan, Henderson Farabow, Garrett and Dunner L.L.P.
Pasterczyk J.
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