CATALYST COMPOSITIONS FOR SELECTIVE DIMERIZATION AND POLYMERIZATION OF ETHYLENE

Abstract

A catalyst composition comprises an inert hydrocarbon solvent, having dissolved therein a titanate of the formula Ti(OR)4 wherein each R is the same or different, and is a hydrocarbon residue, and an organic aluminum compound, wherein a molar ratio of the organic aluminum compound and any alkene present in the catalyst composition is greater than one.

Description

FIELD

Disclosed herein are catalyst systems and processes for the preparation of a polymer from an alkene, preferably a polyethene, or downstream products thereof.

BACKGROUND

Polymers have for a long time been desirable substances in the chemical industry. Polyethene and its derivatives, including co-polymers comprising ethene as one of the co-monomers are of particular commercial interest. One route for the preparation of polymers is by catalysed polymerisation of alkenes. The demand still remains in the state of the art for improved processes for the preparation of polymers from alkenes, especially for processes with long catalyst lifetimes, high specificity, and short induction times.

SUMMARY

A catalyst composition comprises: a titanate of the formula Ti(OR)₄ wherein each R is the same or different, and is a hydrocarbon residue; an ether catalyst modifier, preferably tetrahydrofuran, and an aluminoxane wherein the aluminoxane is a methyl aluminoxane, a modified methyl aluminoxane, or a combination comprising at least one of the foregoing.

A process for the preparation of a downstream polymer product, comprising contacting an alkene with the catalyst composition according to any of the preceding claims under conditions effective to form a polymer.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 represents a schematic process for producing polymer product in accordance with one example of the presently disclosed subject matter.

FIG. 2 represents a schematic process for producing polymer product in accordance with one example of the presently disclosed subject matter.

DETAILED DESCRIPTION

The present invention is generally based on the object of overcoming at least one of the problems encountered in the state of the art in relation to the polymerisation reaction of an alkene, preferably an α-olefin, more preferably ethene, to give a polymer or downstream products derived therefrom.

More specifically, the present invention is further based on the object of providing a catalyst system and a process for a reaction which has a high product specificity, short induction time and a high catalyst lifetime.

Another object is to provide an efficient and sustainable polymer source for producing downstream products and shaped bodies.

A contribution to achieving at least one of the above described objects is made by the subject matter of the category forming claims of the present invention. A further contribution is made by the subject matter of the dependent claims of the present invention which represent specific embodiments of the present invention.

A contribution to achieving at least one of the above-mentioned objects is made by a catalyst composition comprising the following catalyst components:

a. a titanate with the general formula Ti(OR)₄, wherein R is a hydrocarbon residue and each R can be the same as or different to the other R in the molecule;

b. an ether;

c. at least one or more selected from methyl aluminoxane and modified methyl aluminoxane.

In some embodiments of the catalyst composition, constituent c. is modified methyl aluminoxane.

In some embodiments of the catalyst composition, the modified aluminoxane is a copolymer comprising (MeAlO) as a first repeating unit and (RAlO) as a further repeating unit, wherein R is not methyl.

In some embodiments of the catalyst composition, the ratio between the number of first repeating units and the number of further repeating units is in the range from about 20:1 to about 1:1, preferably in the range from about 15:1 to about 5:1, more preferably in the range from about 12:1 to about 8:1.

In some embodiments of the catalyst composition, the catalyst composition comprises a further aluminium compound distinct from the methyl aluminoxane c.

In some embodiments of the catalyst composition, the further aluminium compound has the general formula Al_nR_3n, wherein n is 1 or 2, R is a hydrocarbon residue, H or a halogen, preferably a hydrocarbon residue or a halogen, more preferably an alkyl group or aryl group or halogen, most preferably an alkyl group or a halogen. In one aspect of this embodiment, the further aluminium compound is selected from the group consisting of the following: AlH₃, AlEth₃Cl₃ and AlCl₃.

In some embodiments of the catalyst composition, the molar ratio between the further aluminium compound and the total amount of methyl aluminoxane and modified aluminoxane is in the range from about 1:5 to about 5:1, preferably in the range from about 1:3 to about 3:1, more preferably in the range from about 1:2 to about 2:1.

In some embodiments of the catalyst composition, the catalyst is dissolved in a liquid.

In some embodiments of the catalyst composition, the liquid is an alkane or an alkene.

In some embodiments of the catalyst composition, the liquid is a C₆-C₁₂ alkane or a C₆-C₁₂ alkene.

In some embodiments of the catalyst composition, the liquid is at least one or more selected from the group consisting of butene, hexane, heptane, and octane.

In some embodiments of the catalyst composition, the titanate is Ti(O-butyl)₄.

In some embodiments of the catalyst composition, the titanate is Ti(O-n-alkyl)₄.

In some embodiments of the catalyst composition, the titanate is Ti(O-n-butyl)₄.

In some embodiments of the catalyst composition, the ether is tetrahydrofuran.

A contribution to achieving at least one of the above mentioned objects is made by a process for the preparation of a polymer, wherein an alkene comes into contact with a catalyst composition according to the invention.

In embodiment of the process for the preparation of a polymer, the alkene in ethene.

In embodiment of the process for the preparation of a polymer, the polymer is a polyethene.

In embodiment of the process for the preparation of a polymer, the alkene and the catalyst composition come into contact in a homogeneous liquid phase.

In embodiment of the process for the preparation of a polymer, at least one or both of the following conditions is satisfied:

a. The pressure of the system is in the range from about 5 to about 50 bar;

b. The temperature of the system is in the range from about 40 to about 80° C.

A contribution to achieving at least one of the above mentioned objects is made by a process for the preparation of a downstream product comprising the following preparation steps:

i. preparation of a polymer according to the invention,

ii. reaction of the polymer to obtain the downstream product.

In embodiment of the process for the preparation of a downstream product, the downstream product is converted into a shaped body.

A contribution to achieving at least one of the aforementioned objects is made by a catalyst composition. Preferred catalyst compositions in the context of this invention catalyse the reaction of an alkene, preferably ethene, to obtain a polymer, preferably a polyethene. It is preferred that the catalyst composition contribute to favourable properties of the reaction, preferably to improved catalyst activity, product selectivity of the required polymer, an increased catalyst lifetime.

A preferred catalyst composition comprises a titanate, preferably tetra-n-butyl titanate; an ether catalyst modifier, preferably tetrahydrofuran; one or more selected from the group consisting methyl aluminoxane, modified methyl aluminoxane, and a combination comprising at least one of the foregoing. In some embodiments, the catalyst composition comprises a further aluminium compound distinct from c.

Preferred titanates are compounds of the general formula Ti(OR)₄, wherein R stands for a hydrocarbon residue, preferably an alkyl group or an aryl group, more preferably an alkyl group, and each R in a molecule may be the same as or different to the other R groups in the molecule. Titanates are known to the skilled person, and the specific titanate may be selected in order to enhance the advantageous properties of the process. R is preferably a straight chain or branched alkyl group, more preferably straight chain. R is preferably a C₂-C₁₂ alkyl group, more preferably a C₂-C₈ alkyl group, most preferably a C₃-C₅ alkyl group. The preferred alkyl group is butyl, which includes n-butyl and iso-butyl. Suitable organic titanium compounds include, but are not limited to, tetraethyl titanate, tetraisopropyl titanate, titanium tetra-n-butoxide (TNBT), and tetra-2-ethylhexyl titanate. In some embodiments, the organic titanium compound is titanium tetra-n-butoxide.

In some embodiments, the titanate can be present in high concentration in the reaction mixture, for example in a concentration of about 0.0001 to about 0.1 mol/dm³, about 0.0002 to about 0.01 mol/dm³, more preferably about 0.0005 to about 0.001 mol/dm³.

It is preferred for the methyl aluminoxane and/or modified methyl aluminoxane to act as catalyst activator. The skilled person has knowledge of methyl aluminoxanes and he may select any methyl aluminoxane and/or modified methyl aluminoxane which he considers suitable for increasing favourable properties of the invention. Preferred methyl aluminoxanes are compounds with the general formula (CH₃AlO)_n. Preferred modified methyl aluminoxanes are compounds with the general formula (R_a(CH₃)_bAlO)_n wherein a in the range from 0 to 1 and b is equal to 1-a, and wherein R is not methyl. Preferred R groups in this context are alkyl groups, preferably C₂-C₁₀ alkyl groups, more preferably octyl or butyl, most preferably butyl. It is preferred for a to be in the range from about 0.01 to about 0.5, more preferably in the range from about 0.02 to about 0.4, most preferably in the range from about 0.03 to about 0.35.

The further organic aluminum compound is a compound of the formula AlR₃, wherein R stands for a hydrocarbon, hydrogen or a halogen, preferably a hydrocarbon or a halogen, more preferably alkyl or aryl or halogen, most preferably an alkyl group or halogen and each R in a molecule may be the same as or different to the other R groups in the molecule. Aluminium compounds are known to the skilled person, wherein specific aluminium compounds are selected in order to enhance the advantageous properties of the process. R is preferably a straight chain or branched alkyl group, more preferably straight chain. R is preferably a C₁-C₁₂ alkyl group, more preferably a C₁-C₈ alkyl group, most preferably a C₁-C₄ alkyl group. The preferred alkyl group is ethyl. Suitable organic aluminum compounds include, but are not limited to, triethylaluminum (TEAL), tripropylaluminum, triisobutylaluminum, diisobutylaluminum hydride, and trihexylaluminum. In some embodiments, the organic aluminum compound is triethylaluminum.

In some embodiments, it is preferred for the catalyst composition to comprise a catalyst modifier, in particular an amine catalyst modifier or an ether catalyst modifier. Such ether catalyst modifiers are known, and can act as a co-catalyst or catalyst modifiers to the titanate, preferably by coordination of the titanate with a lone pair of electrons. Such ether catalyst modifiers are well known to the skilled person and he may select any ether which he considers to be appropriate in the context and preferably improving the favourable characteristics of the reaction, preferably a reduced initiation time, increased yield and reduced polymer fouling.

Preferred ether catalyst modifiers may be monoethers or polyethers. Preferred substituents of the ether are alkyl groups. Preferred alkyl groups are methyl, ethyl, propyl, n-butyl, iso-butyl, t-butyl, and other higher alkyl groups. Some preferred monoether catalyst modifiers are dimethyl ether, diethyl ether, dipropyl ether, dibutyl ether, methyl ethyl ether, methyl propyl ether, methyl butyl ether, ethyl propyl ether, ethyl butyl ether, propyl butyl ether, tetrahydrofuran, or dihydropyran. The preferred mono ether is tetrahydrofuran.

Preferred polyether catalyst modifiers are 1,4 dioxane or ethers based on polyalcohols, preferably glycols or glycerols, preferably ethylene glycol. Preferred ethers based on glycol are dimethyl ethylene glycol, diethyl ethylene glycol, dipropyl ethylene glycol, dibutyl ethylene glycol, methyl ethyl ethylene glycol, methyl propyl ethylene glycol, methyl butyl ethylene glycol, ethyl propyl ethylene glycol, ethyl butyl ethylene glycol, propyl butyl ethylene glycol.

In an embodiment an ether catalyst modifier is present, and tetrahydrofuran is preferred. In another embodiment, the catalyst composition contains at least two or more ether catalyst modifiers, preferably with at least one or more, preferably all, as described above, preferably with one of the ethers being tetrahydrofuran.

The skilled person may modify the relative ratios of the components of the catalyst composition in order to increase the advantageous properties of the reaction.

The catalyst composition may be present dissolved in a liquid, preferably an alkane, preferably hexane, preferably as a homogeneous liquid. In an aspect of this embodiment, the liquid is an alkane or an alkene or an aromatic solvent. In a further aspect of this embodiment, the liquid is a C₄-C₁₂ alkane, preferably a C₄-C₈, more preferably a C₄-C₆ alkane; or a C₄-C₁₂ alkene, preferably a C₄-C₈ alkene, more preferably a C₄-C₆ alkene. In a further aspect of this embodiment, the liquid is one or more selected from the group consisting of butene, hexane, heptane, and octane.

The catalyst composition may be pre-prepared or prepared in situ, and preferably is pre-prepared.

When prepared in situ, the components of the catalyst composition are introduced to the reaction system as two or more components that are added sequentially.

In some embodiments, the titanate is pre-mixed with an ether catalyst modifier, optionally together with the catalyst additive. In an aspect of this embodiment, they are mixed in an inert solvent, preferably an alkane, preferably one or more of the following: pentane, hexane, heptane, octane, nonane, or decane, preferably hexane.

In some embodiments, the titanate, the ether catalyst modifier, or a combination thereof, the aluminoxane, and the optional organic aluminum compound are premixed, preferably in the absence of an olefin (alkene). In an aspect of this embodiment, they are mixed in an inert solvent, preferably an alkane, preferably one or more of pentane, hexane, heptane, octane, nonane, or decane, preferably hexane.

In other embodiments, the titanate, the ether catalyst modifier, aluminoxane, and the optional organic aluminium compound are premixed, preferably in the absence of olefin. In one aspect of this embodiment, they are mixed in an inert solvent, preferably an alkane, preferably one or more selected from the group consisting of the following: pentane, hexane, heptane, octane, nonane, decane, preferably hexane. The catalyst additive can further be optionally mixed at the same time with these components in the inert solvent.

In some embodiments, no more than 10% of alkene is present in the preparation of the catalyst compositions. Preferably, no alkene is present in any of the steps of the catalyst preparation. The catalyst composition first comes into contact with alkene during the reaction for the preparation of the α-olefin. In some embodiments, no polymer is present or created in the catalyst composition during its preparation.

In some embodiments, the catalyst composition is prepared shortly before use in the preparation of an α-olefin. It is preferred for the prepared catalyst system not be stored for longer than 1 week, preferably not longer than 1 day, more preferably not longer than 5 hours before being employed as catalyst for the preparation of an α-olefin or other reaction process.

In some embodiments, the catalyst composition is not activated until shortly before being employed in the reaction. It is preferred that the aluminoxane and the optional organic aluminium compound not be brought into contact with the other catalyst components earlier than 30 minutes, preferably not earlier than 15 minutes, more preferably not earlier than 10 minutes, most preferably not earlier than 5 minutes before the catalyst composition is employed in the reaction.

In some embodiments it is preferred for the individual components to be prepared shortly before use. It is preferred that at least one or more of the catalyst components not be stored for longer than 1 week, preferably not longer than 1 day, more preferably not longer than 5 hours after its preparation and before being employed as a component of the catalyst for the reaction. In an aspect of this embodiment, the titanate is not stored for longer than 1 week, preferably not longer than 1 day, more preferably not longer than 5 hours after its preparation and before being employed as a component of the catalyst in the reaction. In an aspect of this embodiment, the organic aluminium compound is not stored for longer than 1 week, preferably not longer than 1 day, more preferably not longer than 5 hours after its preparation and before being employed as a component of the catalyst for the reaction.

A contribution to achieving at least one of the above mentioned objects is made by a reaction process for the preparation of a polymer from an alkene, preferably a reaction process for preparation of a from a C₂-C₈ alkene, most preferably a process for preparation of polyethene from ethene. In some embodiments of a process for the preparation of polymer, an alkene, preferably a C₂-C₈ alkene, most preferably ethene, comes into contact with a catalyst composition as described above. The polymer includes at least 2 repeat units based on the alkene. The alkene and the catalyst may come into contact in a homogeneous liquid phase.

Preferred polymerisation reactions can be mono-polymerization (i.e., homopolymerisation) reactions or copolymerization reactions, preferably copolymerization reactions. The preferred homopolymerisation product is polybutene. The preferred co-polymers comprise units derived from the α-olefin, preferably 1-butene, and one or more co-monomers such as ethene, propene, pentene, styrene, acrylic acid, methacrylic acid, methyl acrylate, methyl methacrylate, acrylonitrile, methacrylonitrile, or vinyl chloride, preferably ethene. The preferred copolymer is a copolymer of ethene and 1-butene, preferably with a larger weight percent (wt. %) of units derived from ethene monomers than of units derived from 1-butene monomers, preferably with a weight ratio of ethene units to 1-butene units of about 50:1 to about 5:1, more preferably about 30:1 to about 10:1, most preferably about 25:1 to about 15:1. The skilled person may vary the ratio relating the mass of ethene monomers and 1-butene monomers in order to achieve the desired properties of the copolymers, such as crystallinity and elasticity.

In some embodiments, the reaction is carried out as a flow reaction. In other embodiments, the reaction is carried out as a batch reaction. It is preferred that the reaction proceed as a homogeneous liquid phase reaction.

FIG. 1 shows a schematic process diagram 100 for an example batch process in accordance with the presently disclosed subject matter. In 101 the catalyst composition is prepared. In 102 the catalyst composition and olefin, e.g., ethylene, are brought into contact in the liquid phase, e.g., in 1-butene as a solvent. In 103 the polymer product of the reaction, e.g., polyethene, is separated from the product mix. Optionally, the catalyst composition can be salvaged from the product mix. The catalyst composition can thus be recycled.

FIG. 2 shows a schematic process diagram 200 for an example flow process in accordance with the presently disclosed subject matter. In 201 the catalyst composition is prepared and introduced into the reaction system, e.g., 1-butene solvent system. The catalyst composition components can either be premixed or added sequentially. In 202 the alkene, e.g., ethylene, is introduced into the reaction system. In 203 the polymer product, e.g., polyethene, is removed from the reaction system.

The skilled person can select the solvent for the reaction process in order to improve the advantageous properties of the reaction. The solvent for the reaction is preferably an alkane, an alkene, or an aromatic hydrocarbon. Preferred alkanes in this context are C₂-C₁₂ alkanes, preferably C₄-C₈ alkanes, most preferably hexane, heptane, or octane, including all isomers of each, and more preferably n-hexane. Preferred alkenes in this context are C₂-C₁₂ alkenes, preferably C₄-C₈ alkenes, including all isomers of each, most preferably butene. Preferred aromatic hydrocarbons in this context are benzene, toluene, and phenol. In some embodiments, the solvent for the reaction is different than the solvent employed for preparation of the catalyst system.

The reaction can be performed at a temperature of from about 20° C. to about 150° C., from about 40° C. to about 100° C., from about 20° C. to about 70° C., from about 50° C. to about 70° C., from about 50° C. to about 55° C., or from about 55° C. to about 65° C. In some embodiments, the reaction is performed at a temperature of about 60° C. The reaction can be performed at a pressure of from about 5 bars to about 50 bars, from about 10 bars to about 40 bars, or from about 15 bars to about 30 bars. In some embodiments, it is preferred that at least one of the following conditions be satisfied during the reaction:

a. the pressure of the system is about 1 to about 50 bar, preferably about 5 to about 50 bar, more preferably about 10 to about 40 bar, most preferably in the range from about 15 to about 30 bar; or

b. the temperature of the system is about 30 to about 150° C., preferably about 40 to about 100° C., more preferably about 50 to about 70° C., most preferably about 55 to about 65° C.

In some embodiments, the reaction is conducted in a batch where a selected volume of the presently disclosed catalyst composition can be introduced into a reactor provided with usual stirring and cooling systems, and can be subjected therein to an ethylene pressure, which can be from about 22 bars to about 27 bars. In some embodiments, the reaction using the presently disclosed catalyst composition is conducted at an ethylene pressure of about 23 bars. One of ordinary skill in the art can adjust the temperature, pressure and other conditions of the reaction in order to bring about favorable properties of the reaction, for example, in order to ensure that the reaction system is present as a homogeneous liquid phase.

The above conditions are particularly preferred where the solvent for the reaction is 1-butene, in order to ensure that the reaction system is present as a homogeneous liquid phase. Where other solvents are used, the skilled person may adjust the temperature, pressure and other conditions of the reaction in order to bring about favourable properties of the reaction and in order to ensure that the reaction system is present as a homogeneous liquid phase. In some embodiments of the process, the alkene and the catalyst come into contact in a liquid phase comprising at least 50 wt. % but-1-ene, based on the total weight of the liquid phase.

The reaction product may be extracted by any method which the skilled person considers to suitable in the context. Preferred methods of extraction include distillation, precipitation, crystallisation, membrane permeation, and the like.

In some embodiments, the polymers are further processed. In an aspect of this embodiment, this further processing preferably involves formation of shaped objects such as plastic parts for electronic devices, automobile parts, such as bumpers, dashboards, or other body parts, furniture, or other parts or merchandise, or for packaging, such as plastic bags, film, or containers.

The following examples are illustrative of the presently disclosed subject matter and they should not be considered as limiting the scope of the subject matter or claims.

EXAMPLES

The following test methods are applicable to the claims, and were used in the Examples.

Polymer fouling was identified by visual inspection and by using a metal spatula to scrape the inside surfaces of the reactor following completion of the reaction. Where polymer fouling occurs, a thin layer of polymer can be seen on the surfaces of the walls of the reactor and/or on the stirrer. The thin polymer layer is white is colour and includes thin strands.

Initiation time was determined by monitoring the pressure in the reactor or the flow rate of the feed to the reactor. Once the reaction starts, ethene feed is consumed.

In a batch reactor, onset of reaction is manifested as a drop in absolute pressure. Thus, pressure remains roughly constant during the initiation period and starts to drop once the initiation period is over. The initiation time is the time spent at roughly constant pressure once the reactants and catalyst have been brought into contact and before the reaction starts.

In a continuous reactor, onset of reaction is manifest as an increase in the flow rate of ethene entering the reactor. At constant pressure, there is roughly no flow of ethene into the reactor during the initiation period. Ethene flows into the reactor once the initiation period is over. The initiation time is the time spent at roughly zero flow rate once the reactants and catalyst have been brought into contact and before the reaction starts.

Example 1

Example 1 illustrates the catalyst system including a tetra-substituted titanate, a dibutyl ether, and trialkyl aluminium, and its use in a process for the preparation of an α-olefin from an alkene, in particular preparation of 1-butene from ethene. The results are summarized in Table 1.

Example 1a. The reaction is carried out in a batch reactor (Parr 300 ml Autoclave Model 4566 Mini Benchtop reactor) at 60° C. and 23 bar. This temperature and pressure ar maintained in the reactor throughout the reaction. 0.25 ml tetra-n-butyl titanate (Dorf KETAL) and 0.25 ml dibutyl ether (Aldrich) are introduced into 50 ml n-hexane (Aldrich). To this is added 1.8 ml 1M solution of triethyl aluminium in n-hexane. The catalyst system in hexane is introduced into the reactor. The reaction system is heated to 60° C. under stirring and pressured to 23 bar with ethene for 1 hour. The product is collected in an adjacent vessel after depressurising.

Example 1b (comparative). Example 1a is repeated except with 0.25 ml tetrahydrofuran in place of 0.25 ml dibutyl ether.

Example 1c. Example la is repeated except with a mixture of 0.125 ml tetrahydrofuran and 0.125 ml dibutyl ether in place of 0.25 ml dibutyl ether.

TABLE 1
	Dibutyl ether
Example	(ml)	Tetrahydrofuran (ml)	Yield	Activation time
1a	0.25	0	High	Short
1b	0	0.25	Medium	Medium
1c	0.125	0.125	Very high	Very short

Example 2

Example 2 illustrates the catalyst system comprising tetraalkyl titanate, a silicate, and trialkyl and its use in a process for the preparation of an α-olefin from an alkene, in particular preparation of 1-butene from ethene. The results are summarized in Table 2.

Example 2a. The reaction was carried out in a batch reactor (Parr 300 ml Autoclave Model 4566 Mini Benchtop reactor) at 60° C. and 23 bars. This temperature and pressure were maintained in the reactor throughout the reaction. 0.25 ml tetra-n-butyl titanate (Dorf KETAL) and 0.25 ml tetraethyl silicate (Aldrich) were introduced into 50 ml n-hexane (Aldrich). To this was added 1.8 ml 1M solution of triethyl aluminium in n-hexane. The catalyst system in hexane was introduced into the reactor. The reaction system was heated to 60° C. under stirring and pressured to 23 bar with ethene for 1 hour. The product was collected in an adjacent vessel after depressurising. The yield of 1-butene, expressed as the percentage based on full conversion of the introduced ethene, was 90%. No polymer fouling was observed.

Example 2b (comparative). Example 2a was repeated except with 9 ml tetrahydrofuran in place of 25 ml tetraethyl silicate. The observed yield was <1%. Some polymer fouling was observed.

	TABLE 2
	Example	Co-catalyst	Yield	Polymer fouling
	2a	Si(OCH2CH3)4	90%	No
	2b	Tetrahydrofuran	<1%	Yes

Example 3

Example 3 illustrates the catalyst system comprising a titanate, an ether, a methyl aluminoxane, and optionally a second aluminum compound, and its use in a process for the preparation of an polymer from an alkene, in particular preparation of polyethylene from ethene.

Example 3a. The reaction was carried out in a batch reactor (Parr 300 ml Autoclave Model 4566 Mini Benchtop reactor) at 60° C. and 23 bar. This temperature and pressure were maintained in the reactor throughout the reaction. 0.25 ml tetra-n-butyl titanate (Dorf KETAL) and 0.25 ml tetrahydrofuran (Aldrich) were introduced into 50 ml n-hexane (Aldrich). To this was added 1.8 ml 1M solution of methyl aluminoxane in n-heptane (MAO). The catalyst system in hexane was introduced into the reactor. The reaction system was heated to 60° C. under stirring and pressured to 23 bar with ethene for 1 hour. The product was collected in an adjacent vessel after depressurising. The yield of polymer, expressed as the percentage based on full conversion of the introduced ethene, was 95%.

Example 3b. Example 3a was repeated except that 1.8 ml 1M solution of modified methyl aluminoxane (CH₃)_0.7(iso-But)_0.3 (MMAO) was employed in place of the methyl aluminoxane.

Example 3c. Example 3a was repeated except that a mixture of 0.9 ml 1M solution of methyl aluminoxane and 0.9 ml 1M triethyl aluminium (TEAL) was employed in place of the methyl aluminoxane.

Example 3d. Example 3a was repeated except that a mixture of 0.9 ml 1M solution of modified methyl aluminoxane (CH₃)_0.7(iso-But)_0.3 and 0.9 ml 1M triethyl aluminium was employed in place of the methyl aluminoxane.

Example 3e (Comparative). Example 3a was repeated except that 1.8 ml 1M solution of triethyl aluminium was employed in place of the methyl aluminoxane.

The results are summarized in Table 3, where results are ranked on a scale of 1 to 5, with 1 being the least favourable and 5 being the most favourable.

TABLE 3
Example	Activator	Yield	Initiation time	Catalyst lifetime
3a	MAO	2	2	2
3b	MMAO	3	3	3
3c	MAO and TEAL	4	4	4
3d	MMAO and TEAL	5	5	5
3e	TEAL	1	1	1

The invention is further illustrated by the following embodiments.

Embodiment 1. A catalyst composition, comprising: a titanate of the formula Ti(OR)₄ wherein each R is the same or different, and is a hydrocarbon residue; an ether catalyst modifier, preferably tetrahydrofuran; and an aluminoxane wherein the aluminoxane is a methyl aluminoxane, a modified methyl aluminoxane, or a combination comprising at least one of the foregoing.

Embodiment 2. The catalyst composition of any one or more of the preceding embodiments, wherein the titanate is Ti(O-butyl)₄, Ti(O-n-alkyl)₄, Ti(O-n-butyl)₄, or a combination comprising at least one of the foregoing;

Embodiment 3. The catalyst composition of any one or more of the preceding embodiments, wherein the modified methyl aluminoxane is a copolymer comprising MeAlO repeating units and R³AlO repeating units wherein R is a C₂-₁₂ hydrocarbon, preferably wherein a ratio of the number of MeAlO repeating units and the number of R³AlO repeating units is about 20:1 to about 1:1.

Embodiment 4. The catalyst composition of any one or more of the preceding embodiments, comprising a further organic aluminium compound distinct from the methyl aluminoxane and from the modified methyl aluminoxane, preferably wherein a molar the ratio between the aluminoxane and the organic aluminium compound is about 1:5 to about 5:1.

Embodiment 5. The catalyst composition of embodiment 4, wherein the organic aluminium compound is of the formula Al_nR_3n, wherein n is 1 or 2 and each R is the same or different, and is hydrogen, a hydrocarbon residue, or halogen, preferably wherein the aluminium compound is triethyl aluminium.

Embodiment 6. A process for the preparation of a polymer, the process comprising contacting an alkene with the catalyst composition according to any of the preceding embodiments under conditions effective to form a polymer.

Embodiment 7. The process according to embodiment 6, wherein the alkene is ethene and the polymer is polyethylene.

Embodiment 8. The process according to embodiment 6 or 7, wherein the contacting is in a homogeneous liquid phase.

Embodiment 9. The process according to any one or more of embodiments 6 to 8, wherein the conditions include at least one of a pressure of about 5 to about 50 bar, or a temperature of about 40 to about 80° C.

Embodiment 10. The process according to embodiment any one or more of embodiments 6 to 9, further comprising shaping the polymer to provide an article.

The term “about” or “substantially” means within an acceptable error range for the particular value as determined by one of ordinary skill in the art, which will depend in part on how the value is measured or determined, i.e., the limitations of the measurement system. For example, “about” can mean a range of up to 20%, up to 10%, up to 5%, and or up to 1% of a given value. The singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. “Or” means “and/or.” Unless defined otherwise, technical and scientific terms used herein have the same meaning as is commonly understood by one of skill in the art to which this invention belongs. The endpoints of all ranges directed to the same component or property are inclusive and independently combinable (e.g., ranges of “less than or equal to 25 wt %, or 5 wt % to 20 wt %,” is inclusive of the endpoints and all intermediate values of the ranges of “5 wt % to 25 wt %,” etc.). Disclosure of a narrower range or more specific group in addition to a broader range is not a disclaimer of the broader range or larger group.

All publications, patents, and patent applications cited herein are hereby expressly incorporated by reference for all purposes to the same extent as if each was so individually denoted.

Although the presently disclosed subject matter and its advantages have been described in detail, it should be understood that various changes, substitutions, and alterations can be made herein without departing from the spirit and scope of the presently disclosed subject matter as defined by the appended claims. Moreover, the scope of the presently disclosed subject matter is not intended to be limited to the particular embodiments described in the specification. Accordingly, the appended claims are intended to include within their scope such modifications.

Claims

1. A catalyst composition, comprising:

a titanate of the formula Ti(OR)4 wherein each R is the same or different, and is a hydrocarbon residue;

an ether catalyst modifier, and

an aluminoxane wherein the aluminoxane is a methyl aluminoxane, a modified methyl aluminoxane, or a combination comprising at least one of the foregoing.

2. The catalyst composition of claim 1, wherein the titanate is Ti(O-butyl)4, Ti(O-n-alkyl)4, Ti(O-n-butyl)4 or a combination comprising at least one of the foregoing.

3. The catalyst composition of claim 1, wherein the modified methyl aluminoxane is a copolymer comprising MeAlO repeating units and R3AlO repeating units wherein R3 is a C2-12 hydrocarbon.

4. The catalyst composition of claim 1, comprising a further organic aluminium compound distinct from the methyl aluminoxane and from the modified methyl aluminoxane.

5. The catalyst composition of claim 4, wherein the organic aluminium compound is of the formula AlnR3n, wherein n is 1 or 2 and each R is the same or different, and is hydrogen, a hydrocarbon residue, or halogen.

6. A process for the preparation of a polymer, the process comprising

contacting an alkene with the catalyst composition according to claim 1 under conditions effective to form a polymer.

7. The process according to claim 6, wherein the alkene is ethene and the polymer is polyethylene.

8. The process according to claim 6, wherein the contacting is in a homogeneous liquid phase.

9. The process according to claim 6, wherein the conditions include at least one of a pressure of about 5 to about 50 bar, or a temperature of about 40 to about 80° C.

10. The process according to claim 6, further comprising shaping the polymer to provide an article.

11. The catalyst composition of claim 1, wherein the ether catalyst modifier comprises tetrahydrofuran.

12. The catalyst composition of claim 3, wherein a ratio of the number of MeAlO repeating units and the number of R3AlO repeating units is about 20:1 to about 1:1.

13. The catalyst composition of claim 4, wherein a molar the ratio between the aluminoxane and the organic aluminium compound is about 1:5 to about 5:1.

14. The catalyst composition of claim 5, wherein the organic aluminium