Patent Application
20200317828
The present invention relates to a modified solid polymethylaluminoxane, as well as to a process for the preparation of a modified solid polymethylaluminoxane. The present invention also relates to a catalytic composition comprising the modified solid polymethylaluminoxane on top of which is supported an olefin polymerisation catalyst. The present invention also relates to an olefin polymerisation process employing the catalytic compositions.
It is well known that ethylene (and α-olefins in general) can be readily polymerised at low or medium pressures in the presence of certain transition metal catalysts. These catalysts are generally known as Zeigler-Natta type catalysts.
A particular group of these Ziegler-Natta type catalysts, which catalyse the polymerization of ethylene (and α-olefins in general), comprise an aluminoxane activator and a metallocene transition metal catalyst. Metallocenes comprise a metal bound between two η5-cyclopentadienyl type ligands. Generally the η5-cyclopentadienyl type ligands are selected from η5-cyclopentadienyl, η5-indenyl and η5-fluorenyl.
Catalytic reactions involving Ziegler-Natta catalysts, in particular metallocene-based catalysts, have traditionally employed the catalyst in solution phase. However, this technique has a number of drawbacks, most notably the difficulty of effectively separating the catalyst from the reaction medium and then recycling it for further use.
Given the high value that industry places on polyethylene (as well as other polyolefins), there is a need for improved solid-phase support materials capable of effectively supporting metallocene-based Ziegler-Natta catalysts.
The present invention was devised with the foregoing in mind.
According to a first aspect of the present invention there is provided a modified solid polymethylaluminoxane, the modified solid polymethylaluminoxane comprising a solid polymethylaluminoxane comprising a repeating moiety having a structure according to formula (I) as defined herein, and at least one organic modifier having a structure according to formula (II) as defined herein, wherein at least a portion of the solid polymethylaluminoxane is associated with the organic modifier.
According to a second aspect of the present invention there is provided a process for the preparation of a modified solid polymethylaluminoxane according to the first aspect of the invention, the process comprising the steps of:
a) providing a solid polymethylaluminoxane comprising a repeating moiety having a structure according to formula (I) as defined herein,
According to a third aspect of the present invention there is provided a modified solid polymethylaluminoxane obtainable, obtained or directly obtained by the process according to the second aspect of the invention.
According to a fourth aspect of the present invention, there is provided a catalytic composition comprising an olefin polymerisation catalyst supported on a modified solid polymethylaluminoxane according to the first or third aspect.
According to a fifth aspect of the present invention, there is provided a process for the preparation of a catalytic composition according to the fourth aspect, the process comprising the steps of:
According to a sixth aspect of the present invention there is provided a process for the preparation of a polyolefin, the process comprising the step of:
The term “alkyl” as used herein refers to a straight or branched chain alkyl moieties, typically having 1, 2, 3, 4, 5 or 6 carbon atoms. This term includes reference to groups such as methyl, ethyl, propyl (n-propyl or isopropyl), butyl (n-butyl, sec-butyl or tert-butyl), pentyl (including neopentyl), hexyl and the like. In particular, an alkyl may have 1, 2, 3 or 4 carbon atoms.
The term “alkenyl” as used herein refers to straight or branched chain alkenyl moieties, typically having 2, 3, 4, 5 or 6 carbon atoms. The term includes reference to alkenyl moieties containing 1, 2 or 3 carbon-carbon double bonds (C═C). This term includes reference to groups such as ethenyl (vinyl), propenyl (allyl), butenyl, pentenyl and hexenyl, as well as both the cis and trans isomers thereof.
The term “alkynyl” as used herein refers to straight or branched chain alkynyl moieties, typically having 2, 3, 4, 5 or 6 carbon atoms. The term includes reference to alkynyl moieties containing 1, 2 or 3 carbon-carbon triple bonds (C≡C). This term includes reference to groups such as ethynyl, propynyl, butynyl, pentynyl and hexynyl.
The term “alkoxy” as used herein refers to —O-alkyl, wherein alkyl is straight or branched chain and comprises 1, 2, 3, 4, 5 or 6 carbon atoms. In one class of embodiments, alkoxy has 1, 2, 3 or 4 carbon atoms. This term includes reference to groups such as methoxy, ethoxy, propoxy, isopropoxy, butoxy, tert-butoxy, pentoxy, hexoxy and the like.
The term “haloalkyl” as used herein refers to an alkyl group wherein at least one hydrogen has been substituted with a halo group selected from chloro, fluoro, bromo and iodo. Haloalkyl are typically, but not always, fluoroalkyls. This term includes reference to trifluoromethyl.
The terms “carbocyclyl”, “carbocyclic” and “carbocycle” as used herein refer to alicyclic moiety having 3, 4, 5, 6, 7 or 8 carbon atoms. The group may be a bridged or polycyclic ring system. More often carbocyclyl groups are monocyclic. This term includes reference to groups such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, norbornyl, bicyclo[2.2.2]octyl and the like.
The terms “heterocyclyl”, “heterocyclic” and “heterocycle” as used herein refer to a saturated (e.g. heterocycloalkyl) or unsaturated (e.g. heteroaryl) heterocyclic ring moiety having from 3, 4, 5, 6, 7, 8, 9 or 10 ring atoms, at least one of which is selected from nitrogen, oxygen, phosphorus, silicon and sulphur. In particular, heterocyclyl includes a 3- to 10-membered ring or ring system and more particularly a 5- or 6-membered ring.
The terms “aryl” and “aromatic” as used herein refer to an aromatic ring system comprising 6, 7, 8, 9 or 10 ring carbon atoms. Aryl is often phenyl but may be a polycyclic ring system, having two or more rings, at least one of which is aromatic. This term includes reference to groups such as phenyl, naphthyl and the like.
The terms “heteroaryl” and “heteroaromatic” as used herein refers to an aromatic heterocyclic ring system having 5, 6, 7, 8, 9 or 10 ring atoms, at least one of which is selected from nitrogen, oxygen and sulphur. The group may be a polycyclic ring system, having two or more rings, at least one of which is aromatic, but is more often monocyclic. This term includes reference to groups such as pyrimidinyl, furanyl, benzo[b]thiophenyl, thiophenyl, pyrrolyl, imidazolyl, pyrrolidinyl, pyridinyl, benzo[b]furanyl, pyrazinyl, purinyl, indolyl, benzimidazolyl, quinolinyl, phenothiazinyl, triazinyl, phthalazinyl, 2H-chromenyl, oxazolyl, isoxazolyl, thiazolyl, isoindolyl, indazolyl, purinyl, isoquinolinyl, quinazolinyl, pteridinyl and the like.
The term “halogen” or “halo” as used herein refer to F, Cl, Br or I. In a particular, halogen may be F or CI, of which CI is more common.
The term “substituted” as used herein in reference to a moiety means that one or more, especially up to 5, more especially 1, 2 or 3, of the hydrogen atoms in said moiety are replaced independently of each other by the corresponding number of the described substituents. The term “optionally substituted” as used herein means substituted or unsubstituted.
It will, of course, be understood that substituents are only at positions where they are chemically possible, the person skilled in the art being able to decide (either experimentally or theoretically) without inappropriate effort whether a particular substitution is possible. For example, amino or hydroxy groups with free hydrogen may be unstable if bound to carbon atoms with unsaturated (e.g. olefinic) bonds. Additionally, it will of course be understood that the substituents described herein may themselves be substituted by any substituent, subject to the aforementioned restriction to appropriate substitutions as recognised by the skilled person.
The first aspect of the invention provides a modified solid polymethylaluminoxane, the modified solid polymethylaluminoxane comprising:
a solid polymethylaluminoxane comprising a repeating moiety having a structure according to formula (I) shown below:
and at least one organic modifier having a structure according to formula (II) shown below:
The modified solid polymethylaluminoxanes of the invention present a number of advantages over other solid polymethylaluminoxanes. Perhaps most notably, the modified solid polymethylaluminoxanes exhibit noticeably higher surface area than their unmodified analogues, thus rendering them ideal candidates for use as supporting materials in catalytic applications, in particular olefin polymerisation reactions. Owing to their superior surface area properties, the modified solid polymethylaluminoxanes are particularly effective support materials for the metallocene Ziegler-Natta-catalysed polymerisation of ethylene.
The modified solid polymethylaluminoxanes of the invention comprise a solid polymethylaluminoxane comprising a repeating moiety having a structure according to formula (I).
Solid polymethylaluminoxanes (also termed solid MAOs or sMAOs) comprising a repeating moiety having a structure according to formula (I) will be familiar to one of ordinary skill in the art. In particular, it will be understood that there exist numerous substantial structural and behavioural differences between solid polymethylaluminoxanes and other (non-solid) methyl aluminoxanes. Perhaps most notably, solid polymethylaluminoxanes are distinguished from other methyl aluminoxanes (MAOs) in that they are insoluble in hydrocarbon solvents and so may act as heterogeneous support systems. Any suitable solid polymethylaluminoxane may be used as part of the present invention.
The solid polymethylaluminoxanes useful in the preparation of the modified solid polymethylaluminoxanes of the invention are insoluble in toluene and hexane. In contrast to non-solid (hydrocarbon-soluble) MAOs, which are traditionally used as an activator species in slurry polymerisation or to modify the surface of a separate solid support material (e.g. SiO2), the solid polymethylaluminoxanes useful as part of the present invention are themselves suitable for use as solid-phase support materials, without the need for an additional activator. Hence, the modified solid polymethylaluminoxanes of the invention are devoid of any other species that could be considered a solid support (e.g. inorganic material such as SiO2, Al2O3 and ZrO2). Similarly, when the modified solid polymethylaluminoxanes of the invention are used in olefin polymerisation applications, the only inorganic solid support present in the catalytic composition is the modified solid polymethylaluminoxanes (i.e. no additional solid support such as SiO2, Al2O3 and ZrO2 are necessary). Moreover, given the dual function of the modified solid polymethylaluminoxanes of the invention (as catalytic support and activator species), the catalytic compositions of the invention contain no additional catalytic activator species.
In an embodiment, the solid polymethylaluminoxanes used in the preparation of the modified solid polymethylaluminoxanes of the invention is prepared by heating a solution containing polymethylaluminoxane and a hydrocarbon solvent (e.g. toluene), so as to precipitate solid polymethylaluminoxane. The solution containing polymethylaluminoxane and a hydrocarbon solvent may be prepared by reacting trimethyl aluminium and benzoic acid in a hydrocarbon solvent (e.g. toluene), and then heating the resulting mixture. Accordingly, the solid polymethylaluminoxane and the resulting modified solid polymethylaluminoxanes of the invention may contain a quantity of residual benzoic acid and/or a quantity of trimethyl aluminium.
In an embodiment, the solid polymethylaluminoxane used in the preparation of the modified solid polymethylaluminoxanes of the invention is prepared according to the following protocol:
The properties of the solid polymethylaluminoxane can be adjusted by altering one or more of the processing variables used during its synthesis. For example, in the above-outlined protocol, the properties of the solid polymethylaluminoxane may be adjusted by varying the Al:O ratio, by fixing the amount of AlMe3 and varying the amount of benzoic acid. Exemplary Al:O ratios are 1:1, 1.1:1, 1.2:1, 1.3:1, 1.4:1 and 1.6:1. Suitably the Al:O ratio is 1.2:1 or 1.3:1. Alternatively, the properties of the solid polymethylaluminoxane may be adjusted by fixing the amount of benzoic acid and varying the amount of AlMe3.
In the above protocol, steps 1 and 3 may be kept constant, with step 2 being varied. The temperature of step 2 may be 70-100° C. (e.g. 70° C., 80° C., 90° C. or 100° C.). The duration of step 2 may be from 12 to 28 hours (e.g. 12, 20 or 28 hours). The duration of step 2 may be from κ minutes to 24 hours. Step 3 may be conducted in a solvent such as toluene.
In a particularly suitable embodiment, the solid polymethylaluminoxane used in the preparation of the modified solid polymethylaluminoxanes of the invention is as described in WO2010/055652 or WO2013/146337, and is obtainable from Tosoh Finechem Corporation, Japan. Suitably, the solid polymethylaluminoxane used in the preparation of the modified solid polymethylaluminoxanes of the invention is as described in WO2010/055652.
The solid polymethylaluminoxane used in the preparation of the modified solid polymethylaluminoxanes of the invention is characterised by having extremely low solubility in toluene and n-hexane. In an embodiment, the solubility in n-hexane at 25° C. of the solid polymethylaluminoxane is 0-2 mol %. Suitably, the solubility in n-hexane at 25° C. of the solid polymethylaluminoxane is 0-1 mol %. More suitably, the solubility in n-hexane at 25° C. of the solid polymethylaluminoxane is 0-0.2 mol %. Alternatively or additionally, the solubility in toluene at 25° C. of the solid polymethylaluminoxane is 0-2 mol %. Suitably, the solubility in toluene at 25° C. of the solid polymethylaluminoxane is 0-1 mol %. More suitably, the solubility in toluene at 25° C. of the solid polymethylaluminoxane is 0-0.5 mol %. The solubility in solvents may be measured by the method described in JP-B(KOKOKU)-H07 42301. The modified solid polymethylaluminoxanes of the invention may exhibit the same solubility properties as the solid polymethylaluminoxanes used in their preparation.
The solid polymethylaluminoxane used in the preparation of the modified solid polymethylaluminoxanes of the invention, or the modified solid polymethylaluminoxanes themselves, may have an aluminium content in the range of 36-41 wt %.
In an embodiment, the modified solid polymethylaluminoxanes have an aluminium content of 30.0-38.5 wt %. Suitably, the modified solid polymethylaluminoxanes have an aluminium content of 30.25-35.0 wt %. More suitably, the modified solid polymethylaluminoxanes have an aluminium content of 30.5-33.0 wt %.
The modified solid polymethylaluminoxanes of the invention comprise at least one organic modifier having a structure according to formula (II). At least a portion of the solid polymethylaluminoxane comprising a repeating moiety having a structure according to formula (I) is associated with the organic modifier. The association between the solid polymethylaluminoxane and the organic modifier can arise as a result of one or more different types of interaction, including ionic, covalent, hydrogen bonding and Van der Waals interactions. The nature of the interaction between the solid polymethylaluminoxane and the organic modifier has an influence of the structure of both components.
The organic modifier is typically associated with at least a portion of the solid polymethylaluminoxane via the former's X1 and X2 groups.
When the organic modifier is not covalently bonded to at least a portion of the solid polymethylaluminoxane, X1 and X2 may be selected from OH, COOH, SH, PRxRyH and NRxH, in which case the organic modifier of formula (II) can be viewed as a free compound having a non-covalent association with at least a portion of the solid polymethylaluminoxane.
Alternatively, or additionally, when the organic modifier is covalently bonded to at least a portion of the solid polymethylaluminoxane, X1 and X2 may exist in a deprotonated form, in which case the organic modifier of formula (II) can be viewed as a structural moiety present within the modified solid polymethylaluminoxanes of the invention. Hence, in an embodiment, at least a portion of the solid polymethylaluminoxane is covalently bonded to the organic modifier, such that at least a portion of the modified solid polymethylaluminoxane has a structure according to formula (III) shown below:
wherein
X1 and X2 are independently selected from O, COO, S, PRxRy and NRx, and
A1, A2, L1, L2, L3, Rx, Ry, m, n, o and p are as defined in formula (II).
Without wishing to be bound by theory, it is believed that the structure of the organic modifiers of formula (II) has an effect on the overall morphology of the modified solid polymethylaluminoxane. In particular, the ability of groups X1 and X2 to each associate with a different particulate of solid polymethylaluminoxane comprising a repeating moiety having a structure according to formula (I) allows for the formation of a network of solid polymethylaluminoxane particulates interconnected by organic modifiers acting as linking groups. It is believed that the formation of such networks results in the creation of channels within the modified solid polymethylaluminoxane, which may contribute to the observed increase in specific surface area.
The following paragraphs provide preferred definitions of the groups X1, X2, A1, A2, L1, L2, L3, Rx, Ry, m, n, o and p of formula (II). It will be appreciated that when the organic modifier is covalently bonded to at least a portion of the solid polymethylaluminoxane, the definitions may be equally applicable to formula (III).
In an embodiment, X1 and X2 are independently selected from OH, COOH, SH, PRxRyH and NRxH, or their deprotonated forms, wherein Rx is independently selected from hydrogen and (1-4C)alkyl.
In an embodiment, X1 and X2 are independently selected from OH, COOH, SH and NRxH, or their deprotonated forms, wherein Rx is independently selected from hydrogen and (1-4C)alkyl.
In an embodiment, X1 and X2 are independently selected from OH, COOH and NRxH, or their deprotonated forms, wherein Rx is independently selected from hydrogen and (1-4C)alkyl.
In an embodiment, X1 and X2 are independently selected from OH and NRxH, or their deprotonated forms, wherein Rx is independently selected from hydrogen and (1-4C)alkyl.
In an embodiment, X1 and X2 are independently selected from OH and COOH, or their deprotonated forms.
In a particularly suitable embodiment, X1 and X2 are OH, or its deprotonated form.
In an embodiment, rings A1 and A2 are independently aromatic or heteroaromatic, and are optionally substituted with one or more groups R1 selected from OH, COOH, NRxRy, halo, (1-5C)alkyl, (2-5C)alkenyl, (2-5C)alkynyl, (1-5C)alkoxy, aryl and heteroaryl, wherein Rx and Ry are independently selected from hydrogen and (1-4C)alkyl.
In an embodiment, rings A1 and A2 are independently monocyclic or bicyclic aromatic or heteroaromatic, and are optionally substituted with one or more groups R1 selected from OH, COOH, NRxRy, halo, (1-5C)alkyl, (2-5C)alkenyl, (2-5C)alkynyl, (1-5C)alkoxy, aryl and heteroaryl, wherein Rx and Ry are independently selected from hydrogen and (1-4C)alkyl.
In an embodiment, rings A1 and A2 are independently monocyclic or bicyclic aromatic or heteroaromatic, and are optionally substituted with one or more groups R1 selected from OH, COOH, NRxRy, halo, (1-5C)alkyl, (1-5C)alkoxy, phenyl and 5-6 membered heteroaryl, wherein Rx and Ry are independently selected from hydrogen and (1-4C)alkyl.
In an embodiment, rings A1 and A2 are independently monocyclic or bicyclic aromatic, and are optionally substituted with one or more groups R1 selected from OH, COOH, NRxRy, halo, (1-5C)alkyl, (1-5C)alkoxy, phenyl and 5-6 membered heteroaryl, wherein Rx and Ry are independently selected from hydrogen and (1-4C)alkyl.
In an embodiment, rings A1 and A2 are independently phenyl or naphthyl, and are optionally substituted with one or more groups R1 selected from OH, COOH, NRxRy, halo, (1-5C)alkyl, (1-5C)alkoxy and phenyl, wherein Rx and Ry are independently selected from hydrogen and (1-4C)alkyl.
In an embodiment, rings A1 and A2 are independently phenyl or naphthyl, and are optionally substituted with one or more groups R1 selected from OH, halo, (1-5C)alkyl and phenyl.
In an embodiment, rings A1 and A2 are independently phenyl or naphthyl, and are optionally substituted with one or more groups R1 selected from OH, chloro, fluoro and (1-3C)alkyl.
In an embodiment, rings A1 and A2 independently have any one the following structures:
wherein
R1 has any of the definitions outlined herein (e.g. halo, such as fluoro),
v is 0 to 4 (e.g. 0 or 4), and
w is 0 to 6 (e.g. 0).
In an embodiment, L1, L2 and L3 are independently selected from (1-5C)alkylene and phenylene, and are optionally substituted with one or more groups selected from OH, halo, (1-3C)alkyl and (1-3C)haloalkyl.
In an embodiment, L1, L2 and L3 are independently selected from (1-3C)alkylene and phenylene, and are optionally substituted with one or more groups selected from OH, halo, (1-3C)alkyl and (1-3C)haloalkyl.
In an embodiment, L1, L2 and L3 are independently selected from (1-3C)alkylene, and are optionally substituted with one or more groups selected from halo, (1-3C)alkyl and (1-3C)haloalkyl.
In an embodiment, L1, L2 and L3 are independently (1-3C)alkylene, and are optionally substituted with one or more groups selected from (1-3C)alkyl and (1-3C)haloalkyl.
In an embodiment, L1, L2 and L3 are methylene, and are optionally substituted with one or more groups selected from (1-2C)alkyl and (1-2C)fluoroalkyl.
In an embodiment, m is 0 or 1.
In an embodiment, m is 0.
In an embodiment, n is 0 or 1.
In an embodiment, n is 1.
In an embodiment, o is 0 or 1.
In an embodiment, o is 1.
In an embodiment, p is 0 or 1.
In an embodiment, p is 0.
In an embodiment, n is 1 and o is 1.
In an embodiment, m is 0 and p is 0.
In a particularly suitable embodiment, m is 0, n is 1, o is 1 and p is 0.
The following paragraphs outline preferred embodiments of the organic modifier of formula (II). It will be appreciated that when the organic modifier is covalently bonded to at least a portion of the solid polymethylaluminoxane, the embodiments may be equally applicable to formula (III).
In an embodiment, X1 and X2 are independently selected from OH, COOH, SH, PRxRyH and NRxH, or their deprotonated forms;
A1 and A2 are independently monocyclic or bicyclic aromatic or heteroaromatic, and are optionally substituted with one or more groups R1 selected from OH, COOH, NRxRy, halo, (1-5C)alkyl, (2-5C)alkenyl, (2-5C)alkynyl, (1-5C)alkoxy, aryl and heteroaryl;
Rx and Ry are independently selected from hydrogen and (1-4C)alkyl;
L2 and L3 are independently selected from (1-3C)alkylene and phenylene, and are optionally substituted with one or more groups selected from OH, halo, (1-3C)alkyl and (1-3C)haloalkyl;
m, n, o and p are independently 0 or 1.
In an embodiment, X1 and X2 are independently selected from OH, COOH and NRxH, or their deprotonated forms;
A1 and A2 are independently monocyclic or bicyclic aromatic or heteroaromatic, and are optionally substituted with one or more groups R1 selected from OH, COOH, NRxRy, halo, (1-5C)alkyl, (2-5C)alkenyl, (2-5C)alkynyl, (1-5C)alkoxy, aryl and heteroaryl;
Rx and Ry are independently selected from hydrogen and (1-4C)alkyl;
L2 and L3 are independently selected from (1-3C)alkylene and phenylene, and are optionally substituted with one or more groups selected from OH, halo, (1-3C)alkyl and (1-3C)haloalkyl;
m, n, o and p are independently 0 or 1.
In an embodiment, X1 and X2 are OH, or its deprotonated form;
A1 and A2 are independently monocyclic or bicyclic aromatic or heteroaromatic, and are optionally substituted with one or more groups R1 selected from OH, COOH, NRxRy, halo, (1-5C)alkyl, (2-5C)alkenyl, (2-5C)alkynyl, (1-5C)alkoxy, aryl and heteroaryl;
Rx and Ry are independently selected from hydrogen and (1-4C)alkyl;
L1, L2 and L3 are independently selected from (1-3C)alkylene and phenylene, and are optionally substituted with one or more groups selected from OH, halo, (1-3C)alkyl and (1-3C)haloalkyl;
m, n, o and p are independently 0 or 1.
In an embodiment, X1 and X2 are OH, or its deprotonated form;
A1 and A2 are independently monocyclic or bicyclic aromatic or heteroaromatic, and are optionally substituted with one or more groups R1 selected from OH, COOH, NRxRy, halo, (1-5C)alkyl, (2-5C)alkenyl, (2-5C)alkynyl, (1-5C)alkoxy, aryl and heteroaryl;
Rx and Ry are independently selected from hydrogen and (1-4C)alkyl;
L1, L2 and L3 are independently selected from (1-3C)alkylene and phenylene, and are optionally substituted with one or more groups selected from OH, halo, (1-3C)alkyl and (1-3C)haloalkyl;
m and p are independently 0 or 1;
n and o are 1.
In an embodiment, X1 and X2 are independently selected from OH, COOH, SH and NRxH, or their deprotonated forms;
rings A1 and A2 are independently monocyclic or bicyclic aromatic or heteroaromatic, and are optionally substituted with one or more groups R1 selected from OH, COOH, NRxRy, halo, (1-5C)alkyl, (1-5C)alkoxy, phenyl and 5-6 membered heteroaryl;
Rx and Ry are independently selected from hydrogen and (1-4C)alkyl;
L1, L2 and L3 are independently (1-3C)alkylene, and are optionally substituted with one or more groups selected from halo, (1-3C)alkyl and (1-3C)haloalkyl;
m, n, o and p are independently 0 or 1.
In an embodiment, X1 and X2 are independently selected from OH, COOH, SH and NRxH, or their deprotonated forms;
rings A1 and A2 are independently phenyl or naphthyl, and are optionally substituted with one or more groups R1 selected from OH, COOH, NRxRy, halo, (1-5C)alkyl, (1-5C)alkoxy and phenyl;
Rx and Ry are independently selected from hydrogen and (1-4C)alkyl;
L1, L2 and L3 are independently (1-3C)alkylene, and are optionally substituted with one or more groups selected from halo, (1-3C)alkyl and (1-3C)haloalkyl;
m, n, o and p are independently 0 or 1.
In an embodiment, X1 and X2 are independently selected from OH, COOH, SH and NRxH, or their deprotonated forms;
rings A1 and A2 are independently phenyl or naphthyl, and are optionally substituted with one or more groups R1 selected from OH, chloro, fluoro and (1-3C)alkyl;
Rx and Ry are independently selected from hydrogen and (1-4C)alkyl;
L1, L2 and L3 are independently (1-3C)alkylene, and are optionally substituted with one or more groups selected from halo, (1-3C)alkyl and (1-3C)haloalkyl;
m, n, o and p are independently 0 or 1.
In an embodiment, X1 and X2 are independently selected from OH, COOH, SH and NRxH, or their deprotonated forms;
rings A1 and A2 independently have any one the following structures:
wherein
R1 has any of the definitions outlined herein (e.g. halo, such as fluoro),
v is 0 to 4 (e.g. 0 or 4), and
w is 0 to 6 (e.g. 0);
Rx and Ry are independently selected from hydrogen and (1-4C)alkyl;
L1, L2 and L3 are independently (1-3C)alkylene, and are optionally substituted with one or more groups selected from halo, (1-3C)alkyl and (1-3C)haloalkyl;
m, n, o and p are independently 0 or 1.
In an embodiment, X1 and X2 are independently selected from OH, COOH, SH and NRxH, or their deprotonated forms;
rings A1 and A2 independently have any one the following structures:
wherein
R1 is selected from OH, COOH, NRxRy, halo (e.g. fluoro), (1-5C)alkyl, (1-5C)alkoxy and
phenyl, and
v is 0 or 4;
Rx and Ry are independently selected from hydrogen and (1-4C)alkyl;
L1, L2 and L3 are independently (1-3C)alkylene, and are optionally substituted with one or more groups selected from halo, (1-3C)alkyl and (1-3C)haloalkyl;
m and p are independently 0 or 1;
n and o are 1.
In an embodiment, X1 and X2 are independently selected from OH, COOH, SH and NRxH, or their deprotonated forms;
A1 and A2 are independently monocyclic or bicyclic aromatic, and are optionally substituted with one or more groups R1 selected from OH, COOH, NRxRy, halo, (1-5C)alkyl, (1-5C)alkoxy, phenyl and 5-6 membered heteroaryl;
Rx and Ry are independently selected from hydrogen and (1-4C)alkyl;
L1, L2 and L3 are independently selected from (1-5C)alkylene and phenylene, and are optionally substituted with one or more groups selected from OH, halo, (1-3C)alkyl and (1-3C)haloalkyl;
m, n, o and p are independently 0 or 1.
In an embodiment, X1 and X2 are independently selected from OH, COOH, SH and NRxH, or their deprotonated forms;
A1 and A2 are independently monocyclic or bicyclic aromatic, and are optionally substituted with one or more groups R1 selected from OH, COOH, NRxRy, halo, (1-5C)alkyl, (1-5C)alkoxy, phenyl and 5-6 membered heteroaryl;
Rx and Ry are independently selected from hydrogen and (1-4C)alkyl;
L1, L2 and L3 are independently (1-3C)alkylene, and are optionally substituted with one or more groups selected from (1-3C)alkyl and (1-3C)haloalkyl;
m, n, o and p are independently 0 or 1.
In an embodiment, X1 and X2 are independently selected from OH, COOH, SH and NRxH, or their deprotonated forms;
A1 and A2 are independently monocyclic or bicyclic aromatic, and are optionally substituted with one or more groups R1 selected from OH, COOH, NRxRy, halo, (1-5C)alkyl, (1-5C)alkoxy, phenyl and 5-6 membered heteroaryl;
Rx and Ry are independently selected from hydrogen and (1-4C)alkyl;
L1, L2 and L3 are methylene, and are optionally substituted with one or more groups selected from (1-2C)alkyl and (1-2C)fluoroalkyl;
m, n, o and p are independently 0 or 1.
In an embodiment, X1 and X2 are independently selected from OH, COOH, SH and NRxH, or their deprotonated forms;
A1 and A2 are independently monocyclic or bicyclic aromatic, and are optionally substituted with one or more groups R1 selected from OH, COOH, NRxRy, halo, (1-5C)alkyl, (1-5C)alkoxy, phenyl and 5-6 membered heteroaryl;
Rx and Ry are independently selected from hydrogen and (1-4C)alkyl;
L1, L2 and L3 are methylene, and are optionally substituted with one or more groups selected from (1-2C)alkyl and (1-2C)fluoroalkyl;
m and p are independently 0 or 1;
n and o are 1.
In an embodiment, X1 and X2 are independently selected from OH, COOH, SH and NRxH, or their deprotonated forms;
rings A1 and A2 are independently monocyclic or bicyclic aromatic or heteroaromatic, and are optionally substituted with one or more groups R1 selected from OH, COOH, NRxRy, halo, (1-5C)alkyl, (1-5C)alkoxy, phenyl and 5-6 membered heteroaryl;
Rx and Ry are independently selected from hydrogen and (1-4C)alkyl;
L1, L2 and L3 are independently (1-3C)alkylene and phenylene, and are optionally substituted with one or more groups selected from OH, halo, (1-3C)alkyl and (1-3C)haloalkyl;
m, n, o and p are independently 0 or 1.
In an embodiment, X1 and X2 are independently selected from OH, COOH and NRxH, or their deprotonated forms;
rings A1 and A2 are independently phenyl or naphthyl, and are optionally substituted with one or more groups R1 selected from OH, COOH, NRxRy, halo, (1-5C)alkyl, (1-5C)alkoxy and phenyl;
Rx and Ry are independently selected from hydrogen and (1-4C)alkyl;
L1, L2 and L3 are independently (1-3C)alkylene, and are optionally substituted with one or more groups selected from (1-3C)alkyl and (1-3C)haloalkyl;
m and p are independently 0 or 1;
n and o are 1.
In an embodiment, X1 and X2 are independently selected from OH and COOH, or their deprotonated forms;
rings A1 and A2 are independently phenyl or naphthyl, and are optionally substituted with one or more groups R1 selected from OH, chloro, fluoro and (1-3C)alkyl;
L1, L2 and L3 are methylene, and are optionally substituted with one or more groups selected from (1-2C)alkyl and (1-2C)fluoroalkyl;
m and p are independently 0 or 1;
n and o are 1.
In an embodiment, X1 and X2 are independently selected from OH and COOH (e.g. OH), or their deprotonated forms;
ring A1 is unsubstituted phenyl or phenyl substituted with one, two, three or four (e.g. three or four) groups R1 selected from chloro and fluoro (e.g. fluoro); and
m, n, o and p are 0.
In an embodiment, X1 and X2 are OH or its deprotonated form;
ring A1 is phenyl substituted with three or four groups R1 being fluoro; and
m, n, o and p are 0.
In an embodiment, X1 and X2 are OH, or its deprotonated form;
rings A1 and A2 independently have any one the following structures:
wherein
R1 has any of the definitions outlined herein (e.g. halo, such as fluoro),
v is 0 to 4 (e.g. 0 or 4), and
w is 0 to 6 (e.g. 0).
L1, L2 and L3 are methylene, and are optionally substituted with one or more groups selected from (1-2C)alkyl and (1-2C)fluoroalkyl;
m and p are independently 0 or 1;
n and o are 1.
In an embodiment, X1 and X2 are OH, or its deprotonated form;
ring A1 has any one of the following structures:
wherein
each R1 is independently chloro or fluoro (e.g. fluoro), and
v is 0, 1, 2, 3 or 4 (e.g. 0, 3 or 4); and
m, n, o and p are 0.
In an embodiment, X1 and X2 are OH, or its deprotonated form;
ring A1 has the following structure:
wherein
each R1 is independently chloro or fluoro (e.g. fluoro), and
In an embodiment, X1 and X2 are OH, or its deprotonated form;
ring A1 has the following structure:
wherein
each R1 is fluoro, and
v is 3 or 4; and
m, n, o and p are 0.
In an embodiment, the organic modifier has any one or more of the following structures:
wherein X1 and X2 are independently selected from OH, COOH, SH, PRxRyH and NRxH, or their deprotonated forms, wherein Rx and Ry are independently selected from hydrogen and (1-4C)alkyl. Suitably, X1 and X2 are independently selected from OH, COOH, SH and NRxH, or their deprotonated forms, wherein Rx is independently selected from hydrogen and (1-4C)alkyl. More suitably, X1 and X2 are independently selected from OH, COOH and NRxH, or their deprotonated forms, wherein Rx is independently selected from hydrogen and (1-4C)alkyl. Most suitably, X1 and X2 are OH, or its deprotonated form.
The amount of organic modifier of formula (II) within the modified solid polymethylaluminoxane is calculated relative to the number of moles of aluminium within the solid polymethylaluminoxane comprising a repeating moiety of formula (I). The amount of organic modifier within a sample of modified solid polymethylaluminoxane can be determined by techniques such as elemental analysis and NMR spectroscopy.
In an embodiment, the modified solid polymethylaluminoxane comprises 0.1-45 mol % of organic modifier of formula (II) relative to the number of moles of aluminium within the solid polymethylaluminoxane comprising a repeating moiety of formula (I). Suitably, the modified solid polymethylaluminoxane comprises 0.1-20 mol % of organic modifier of formula (II) relative to the number of moles of aluminium within the solid polymethylaluminoxane comprising a repeating moiety of formula (I). Suitably, the modified solid polymethylaluminoxane comprises 0.5-15 mol % of organic modifier of formula (II) relative to the number of moles of aluminium within the solid polymethylaluminoxane comprising a repeating moiety of formula (I). More suitably, the modified solid polymethylaluminoxane comprises 1-5 mol % of organic modifier of formula (II) relative to the number of moles of aluminium within the solid polymethylaluminoxane comprising a repeating moiety of formula (I). Yet more suitably, the modified solid polymethylaluminoxane comprises 1.5-3.5 mol % of organic modifier of formula (II) relative to the number of moles of aluminium within the solid polymethylaluminoxane comprising a repeating moiety of formula (I). Yet even more suitably, the modified solid polymethylaluminoxane comprises 2.0-3.0 mol % of organic modifier of formula (II) relative to the number of moles of aluminium within the solid polymethylaluminoxane comprising a repeating moiety of formula (I). Yet even more suitably, the modified solid polymethylaluminoxane comprises 2.2-2.8 mol % of organic modifier of formula (II) relative to the number of moles of aluminium within the solid polymethylaluminoxane comprising a repeating moiety of formula (I). Most suitably, the modified solid polymethylaluminoxane comprises 2.35-2.65 mol % of organic modifier of formula (II) relative to the number of moles of aluminium within the solid polymethylaluminoxane comprising a repeating moiety of formula (I)
At least a portion of the organic modifier of formula (II) present within the modified solid polymethylaluminoxane is associated with the solid polymethylaluminoxane comprising a repeating moiety of formula (I). In an embodiment, at least 30% of the organic modifier of formula (II) present within the modified solid polymethylaluminoxane is associated with the solid polymethylaluminoxane comprising a repeating moiety of formula (I). Suitably, at least 50% of the organic modifier of formula (II) present within the modified solid polymethylaluminoxane is associated with the solid polymethylaluminoxane comprising a repeating moiety of formula (I). More suitably, at least 80% of the organic modifier of formula (II) present within the modified solid polymethylaluminoxane is associated with the solid polymethylaluminoxane comprising a repeating moiety of formula (I).
The modified solid polymethylaluminoxane may have a specific surface area (calculated by N2 physisorbtion using Brunauer-Emmett-Teller (BET) theory) of >10 m2 g−1 (e.g. 10-50 m2 g−1). Suitably, the modified solid polymethylaluminoxane has a specific surface area of >14 m2 g−1 (e.g. 14-50 m2 g−1). More suitably, the modified solid polymethylaluminoxane has a specific surface area of >18 m2 g−1 (e.g. 18-45 m2 g−1). Most suitably, the modified solid polymethylaluminoxane has a specific surface area of >20 m2 g−1 (e.g. 20-40 m2 g−1).
The second aspect of the invention provides a process for the preparation of a modified solid polymethylaluminoxane according to the first aspect of the invention, the process comprising the steps of:
It will be appreciated that the solid polymethylaluminoxane comprising a repeating moiety having a structure according to formula (I) may be as defined in any of those embodiments outlined hereinbefore in respect of the first aspect of the invention.
It will be appreciated that the organic modifier having a structure according to formula (II) may be as defined in any of those embodiments outlined hereinbefore in respect of the first aspect of the invention.
In an embodiment, the mole ratio of the organic modifier to the aluminium in the solid polymethylaluminoxane in step b) ranges from 0.005:1 to 0.2:1. Suitably, the mole ratio of the organic modifier to the aluminium in the solid polymethylaluminoxane in step b) ranges from 0.005:1 to 0.15:1. Suitably, the mole ratio of the organic modifier to the aluminium in the solid polymethylaluminoxane in step b) ranges from 0.01:1 to 0.05:1. More suitably, the mole ratio of the organic modifier to the aluminium in the solid polymethylaluminoxane in step b) ranges from 0.015:1 to 0.035:1. Even more suitably, the mole ratio of the organic modifier to the aluminium in the solid polymethylaluminoxane in step b) ranges from 0.02:1 to 0.03:1. Yet even more suitably, the mole ratio of the organic modifier to the aluminium in the solid polymethylaluminoxane in step b) ranges from 0.022:1 to 0.028:1. Most suitably, the mole ratio of the organic modifier to the aluminium in the solid polymethylaluminoxane in step b) ranges from 0.0235:1 to 0.0265:1.
In an embodiment, the first solvent is selected from toluene, benzene and hexane. Suitably the first solvent is toluene.
In an embodiment, the organic modifier is provided in a second solvent, and step b) comprises mixing the first solvent and the second solvent. The second solvent may be selected from toluene, benzene and hexane. Suitably, the second solvent is toluene.
In an embodiment, step b) is conducted at a temperature of 10-150° C. Suitably, step b) is conducted at a temperature of 10-65° C. More suitably, step b) is conducted at a temperature of 18-50° C. Yet more suitably, step b) is conducted at a temperature of 18-35° C.
In an embodiment, step b) further comprises the step of sonicating the mixture of the solid polymethylaluminoxane and the organic modifier, for example at an ultrasonic frequency of >15 kHz. The use of sonication advantageously obviates the need for conducting step b) at high temperatures, which is believed to result in degradation of the modified solid polymethylaluminoxane. In an embodiment, when step b) comprises sonicating the mixture of the solid polymethylaluminoxane and the organic modifier, the temperature of the mixture does not rise above 85° C. over the course of step b). Suitably, when step b) comprises sonicating the mixture of the solid polymethylaluminoxane and the organic modifier, the temperature of the mixture does not rise above 65° C. over the course of step b).
In an embodiment, step b) is carried out under soniciation for a period of 0.1 to 24 hours. Suitably, step b) is carried out under soniciation for a period of 0.1 to 5 hours.
The fourth aspect of the invention provides a catalytic composition comprising an olefin polymerisation catalyst supported on a modified solid polymethylaluminoxane according to the first or third aspect.
Any suitable olefin polymerisation catalyst may be used in the catalytic composition. In an embodiment, the olefin polymerisation catalyst is a Ziegler-Natta type catalyst (e.g. a metallocene-based Ziegler-Natta catalyst).
In an embodiment, the olefin polymerisation catalyst is a metallocene catalyst comprising a metal bound between two η5-cyclopentadienyl type ligands. The η5-cyclopentadienyl type ligands may be selected from η5-cyclopentadienyl, η5-pentalenyl, η5-indenyl and η5-fluorenyl.
In an embodiment, the olefin polymerisation catalyst has a structure according to formula (IV) shown below:
wherein
It will be appreciated that the structural formula (IV) presented above is intended to show the substituent groups in a clear manner. A more representative illustration of the spatial arrangement of the groups is shown in the alternative representation below:
It will also be appreciated that, depending on the identities of substituents Ra-Rh, the compound of formula (IV) may be present as meso or rac isomers, and the present invention includes both such isomeric forms. A person skilled in the art will appreciate that a mixture of isomers of the compound of formula (IV) may be used for catalysis applications, or the isomers may be separated and used individually (using techniques well known in the art, such as, for example, fractional crystallization).
If the structure of a compound of formula (IV) is such that rac and meso isomers do exist, the compound may be present in the rac form only, or in the meso form only.
The compound of formula (IV) may be immobilized on the solid phase support material by one or more ionic or covalent interactions.
In the catalytic compositions of the invention, the modified solid polymethylaluminoxane of the invention are the only inorganic solid supports used (i.e. no additional solid support such as SiO2, Al2O3 and ZrO2 are necessary). Moreover, given the dual function of the modified solid polymethylaluminoxane of the invention (as catalytic support and activator species), the catalytic compositions of the invention contain no additional catalytic activator species (e.g. co-catalysts).
The respective amounts of the modified solid polymethylaluminoxane and the compound of formula (IV) within the catalytic composition of the invention is expressed by molAl/molX (i.e. the number of moles of Al (from the modified solid polymethylaluminoxane) divided by the number of moles of metal X (from the compound of formula (IV)). In an embodiment, molAl/molX is 25-250. Suitably, molAl/molX is 40-225. More suitably, molAl/molX is 75-225. Even more suitably, molAl/molX is 100-225. Yet more suitably, molAl/molX is 125-225. Yet even more suitably, molAl/molX is 150-225. Most suitably, molAl/molX is 175-225.
In an embodiment, Ra and Rb are each hydrogen.
In an embodiment, Rc and Rd are each independently hydrogen or (1-4C)alkyl, or Rc and Rd are linked such that, when taken in combination with the atoms to which they are attached, they form a 6-membered fused aromatic ring optionally substituted with one or more groups selected from (1-6C)alkyl, (2-6C)alkenyl, (2-6C)alkynyl and (1-6C)alkoxy.
Suitably, Rc and Rd are each independently hydrogen or (1-4C)alkyl, or Rc and Rd are linked such that, when taken in combination with the atoms to which they are attached, they form a 6-membered fused aromatic ring optionally substituted with one or more groups selected from methyl, ethyl and tert-butyl.
In an embodiment, Re and Rf are each independently hydrogen or (1-4C)alkyl, or Re and Rf are linked such that, when taken in combination with the atoms to which they are attached, they form a 6-membered fused aromatic ring optionally substituted with one or more groups selected from (1-6C)alkyl, (2-6C)alkenyl, (2-6C)alkynyl and (1-6C)alkoxy.
Suitably, Re and Rf are each independently hydrogen or (1-4C)alkyl, or Re and Rf are linked such that, when taken in combination with the atoms to which they are attached, they form a 6-membered fused aromatic ring optionally substituted with one or more groups selected from methyl, ethyl and tert-butyl.
In an embodiment, Rg and Rh are each independently hydrogen or (1-4C)alkyl, or Rg and Rh are linked such that, when taken in combination with the atoms to which they are attached, they form a 6-membered fused aromatic ring optionally substituted with one or more groups selected from (1-6C)alkyl, (2-6C)alkenyl, (2-6C)alkynyl and (1-6C)alkoxy.
Suitably, Rg and Rh are each independently hydrogen or (1-4C)alkyl, or Rg and Rh are linked such that, when taken in combination with the atoms to which they are attached, they form a 6-membered fused aromatic ring optionally substituted with one or more groups selected from methyl, ethyl and tert-butyl.
In an embodiment, Q is absent, or is a bridging group selected from —CH2— or —CH2CH2—, either or which may be optionally substituted with one or more groups selected from (1-4C)alkyl and phenyl, or Q is a bridging group —Si(Ri)(Rj)—,
wherein Ri and Rj are independently (1-4C)alkyl or aryl.
In an embodiment, X is zirconium.
In an embodiment, each Y group is independently selected from halo.
Suitably, each Y group is chloro.
In an embodiment, the olefin polymerisation catalyst having a structure according to formula (IV) has any of the structures shown below:
In a particular embodiment, the olefin polymerisation catalyst has a structure according to formula (IV) has the following structure:
The fifth aspect of the invention provides a process for the preparation of a catalytic composition according to the fourth aspect, the process comprising the steps of:
The olefin polymerisation catalyst may have any of those definitions discussed hereinbefore in respect of the fourth aspect of the invention.
The catalytic compositions of the invention are straightforwardly prepared using mild reaction conditions.
Suitable solvents for use in step a) will be well known to one of ordinary skill in the art, and include toluene, o-xylene, mesitylene, pentane, hexane, heptane, cyclohexane and methylcyclohexane. Suitably, the solvent used in step a) is toluene.
Step b) may involve mixing the reagents for a period of 0.05-6 hours. Step b) may be conducted at a temperature of 1-3 hours.
The sixth aspect of the invention provides a process for the preparation of a polyolefin, the process comprising the step of:
In an embodiment, the polyolefin is polyethylene and the olefin monomers are ethene monomers.
In another embodiment, the polyolefin is a copolymer, and the olefin monomers are a mixture of monomers comprising 90-99 wt % ethene and 1-10 wt % of one or more (4-8C) α-olefin. Suitably, the (4-8C) α-olefin is 1-butene, 1-hexene, 1-octene, or a mixture thereof.
A person skilled in the art of olefin polymerisation will be able to select suitable reaction conditions (e.g. temperature, pressures, reaction times etc.) for such a polymerisation reaction. A person skilled in the art will also be able to manipulate the process parameters in order to produce a polyolefin having particular properties
One or more examples of the invention will now be described, for the purpose of illustration only, with reference to the accompanying figures, in which:
A study into the effect of various aromatic di-ol modifying compounds (M) on solid polymethylaluminoxane was carried out, using a M:Al mol ratio of 0.025.
In a typical experiment, solid polymethylaluminoxane (sMAO, supplied by TOSOH Finechem) was suspended in toluene and a solution of the modifier in toluene was added. In the case of the modifiers which showed poor toluene solubility, the two solid reagents were combined in the same Schlenk flask, to which toluene was added. The mixture was sonicated for 1 h, during which time the temperature increased from 25 to 45° C.
Upon addition of these aromatic di-ol modifiers to sMAO, effervescence was observed, confirming a protonolysis reaction with concomitant release of methane gas. A control reaction was also carried out, using an identical procedure but without the addition of a modifying compound.
After cooling to room temperature, the resultant slurry was then treated with hexane to extract by-products and encourage precipitation of a colourless solid. After settling, the supernatant solution was removed and the solid modified polymethylaluminoxane (sMMAO) samples were vacuum dried and isolated in good yield (59-91%).
For completeness, a detailed synthetic protocol using 1,4-HO(C6F4)OH as the modifier is outlined below.
To a round-bottom flask containing a dispersion of sMAO (680 mg, 10.07 mmolAl) in toluene (5 mL) was added a solution of 1,4-HO(C6F4)OH (46 mg, 0.253 mmol) in toluene (3×5 mL) and the flask was swirled at ambient temperature for 1 h. Hexane (60 mL) was added and the resultant off-white suspension was allowed to settle. The supernatant solution was removed by filtration and the remaining solids were dried in vacuo for 3 h, to afford sMMAO(0.025/1,4-HO(C6F4)OH) as a free-flowing white solid. Total yield: 593 mg, 6.92 mmolAl (69% based on aluminum).
Once prepared, the various sMMAO(0.025/M) samples were characterised using BET isotherm, SEM imaging and NMR spectroscopy in the solution (THF-d8) and solid state.
The specific surface area of the sMMAO samples was determined by analysis of N2 gas physisorbtion using Brunauer-Emmett-Teller (BET) theory. The BET data obtained (
The DRIFT spectrum of sMMAO(0.05/1,4-HO(C6F4)OH) (
The linked sMMAO samples were sparingly soluble in THF-d8, allowing for their characterisation by solution NMR spectroscopy. A selected region of the 1H NMR spectrum of sMMAO(0.025/1,4-HO(C6F4)OH) is shown in
The 1H NMR spectrum shows a resonance between 0.03 and −1.57 ppm, assigned to the methyl protons of the solid MAO, which is very broad due to the oligomeric nature of the material. Within this broad feature is a sharp signal at −0.60 ppm, which is assigned to the methyl protons of TMA ‘bound’ within the sMAO structure. The sharp signal at −0.96 ppm is assigned to ‘free’ TMA, which is an inherent part of MAO compositions. The sMMAO samples all show an additional signal in the region −0.6 to −0.8 ppm, which is assigned to an aluminoxane methyl group adjacent to a modifier group in the oligomeric chain. In the 1H NMR spectrum of sMMAO(0.025/1,4-HO(C6F4)OH) this appears as a low intensity broad resonance at −0.85 ppm (
19F{1H} NMR spectroscopy is a powerful characterisation technique in the case of the fluorinated modifiers, in order to determine the symmetry and chemical environment of the linker groups. The 19F{1H} NMR spectrum of sMMAO(0.025/1,4-HO(C6F4)OH) (
In the case of sMMAO(0.05/1,4-HOOC(C8F4)COOH) with modifying linker tetrafluoroterephthalic acid, the 1H NMR spectrum showed sharp resonances that may be assigned to ‘free’ and ‘bound’ TMA methyl groups. However, the broad resonance attributed to the oligomeric sMAO methyl groups was not observed, perhaps suggesting either that a methylaluminoxane-based material was not formed, or that its solubility in THF-d8 was extremely low.
In the case of sMMAO(0.05/1,4-HOOC(C6F4)COOH) with modifying linker tetrafluoroterephthalic acid, the 19F NMR spectrum showed a single weak intensity resonance at δF−143.3 ppm. The low signal intensity of this resonance is attributed to the very poor solubility in THF-d8 of this sample. For comparison, the 19F NMR spectrum of the starting material 1,4-HOOC(C6F4)COOH in THF-d8 showed a single resonance at δF −141.0 ppm. The slight shift in δF suggests a reaction may have taken place, to yield a sMMAO that features a symmetrical —OOC(C6F4)COO— linking group. However, due to the poor solubility of this material, solid state NMR studies are required to confirm this postulate.
Solid state NMR spectroscopy allows for characterisation of poorly soluble samples 1,4-HO(C6F4)OH.
The 13C-1H CP-MAS SSNMR spectrum of sMMAO(0.05/1,4-HO(C6F4)OH) (
Total X-ray scattering pair distribution function (XPDF) of amorphous sMAO and linker modified sMMAO supports was used as an additional characterisation technique. Samples linker modified sMMAOs were sealed under argon in glass capillaries and were subject to total X-ray scattering measurements using a synchrotron radiation, resulting in a useable Q-range from 0.4-12 Å−1. The pair distribution function (PDF) was obtained by subtracting scattering from the argon-filled sample container and Fourier transforming the corrected total X-ray scattering data in GudrunX. The PDF for sMMAO(1,4-HO(C6F4)OH) samples reveals a D(r) increase at 1.34, 2.36, 2.84 and 3.62 Å with increased modifier loading, and peaks are also observed in these positions in the PDF of pure HO(C6F4)OH linker.
The XPDF technique provides further evidence for incorporation of —O(C6F4)O— units in the sMMAO, which have a rigid structure and, therefore a significant effect on the PDF. The most intense peak in the sMAO sample at ca. 1.82 Å, assigned to Al—O and Al—C correlations in the aluminoxane backbone, decreases in intensity with increased modifier loading. This may be attributed to the reduced number of Al—C bonds as free trimethylaluminium reacts to forms Al—O bonds in the modified material. PDF peaks at 3.14 and 4.53 Å, assigned to Al—Al correlations in sMAO, diminish in intensity in sMMAO(1,4-HO(C6F4)OH) with increasing modifier loading. These peaks have been assigned to Al—Al, Al—O and C—O correlations in unmodified sMAO, and their decreasing intensity is consistent with diminishing number of Al—O—Al moieties as the modifier breaks up the aluminoxane clusters.
The aluminium content in the sMMAO samples was determined by ICP-MS analysis (Table 1), which shows a progressive decrease in Al with increasing M loading from 39.5 wt % for the control sMAO to ca. 16 wt % in the sMMAO(0.40/1,4-HO(C6F4)OH). This is consistent with the replacement of Al-bound methyl groups with heavier modifier groups. The amount of fluorine, as quantified by elemental analysis is 22.4 wt % for sMMAO(0.40/1,4-HO(C6F4)OH), which corresponds to 0.49 moles of —(C6F4)— linker groups per mole aluminium. Thus confirming that the protonolysis reaction of with sMAO with 1,4-HO(C6F4)OH is quantitative with respect to the modifier loading.
In order to determine which ratio of di-ol modifier to sMAO would produce the best polymerisation activity, a loading study was carried out with sMMAO(x/1,4-HO(C5F4)OH) where x=0.01, 0.025, 0.05 molM/molAl. (EBI)ZrCl2 was immobilised on sMMAO(HOC6F4OH) at [Al]/[Zr]=200 by swirling both the complex and the support in a toluene solution (40 mL). The complex was fully immobilised as judged by a colourless supernatant solution. The results are summarised in Table 2.
It is noted that for all mol ratios, the BET surface area was higher than for the unmodified control. There is a decrease in BET surface area as the modifier loading is increased, the reasons for this are unclear but may be explained by SEM imaging of the support samples. The optimum polymerisation activity is found at x=0.025 molM/molAl, so this loading was used in subsequent experiments with a range of linker modifiers.
Scanning electron microscopy (SEM) images of polyethylene samples on carbon tape (
The polyethylene samples for x=0.01 show good morphology control with respect to the unmodified samples, but interestingly show some ‘bobble’ areas on the PE surface. By analogy with the template effect these supports have on the PE produced, these ‘bobbles’ may explain the very high BET surface area for this support (33.2 m2 mmol−1). The polyethylene samples for x=0.025 also show good morphology with respect to the control, but the areas of ‘bobbles’ are less pronounced on the PE surface for these imaged particles. This may explain the slightly lower BET surface area for this support (27.8 m2 mmol−1) relative to the PE produced from the sMMAO(0.01/HOC6F4OH) based catalyst. Surprisingly, the polyethylene samples for x=0.05 show a morphology which is very different from the control. The more pronounced ‘knobbly’ structure is present across the PE particles, as revealed in the image at ×4000 magnification (
Using the synthetic protocol outlined in Example 1.1, a study into the effect of 9 aromatic di-ol modifying compounds was carried out, using a Al:M mol ratio of 0.025.
Scanning electron microscopy (SEM) images of the sMMAO(0.025/M) samples with M=HO(C6H4)—(C6H4)OH and 1,2-HO(C6H4)OH are shown in
To a round flask charged with sMMAO (265 mg) was added a solution of (EBI)ZrCl2 (4.7 mg, 0.011 mmol) in toluene (3×5 mL), and the resulting orange dispersion was swirled at ambient temperature for 1 h. The mixture was allowed to settle giving a yellow solid below a colourless supernatant solution. The supernatant was removed by filtration and the remaining slurry was dried in vacuo for 3 h, to afford a free-flowing yellow solid. Total yield: 223 mg. ICP-MS: Al, 23.7 wt %; Zr, 0.48 wt %; molAl/molZr=179.
The coloured solids were then tested for polymerisation capability, the results of which are outlined in Table 3.
§
§
§Unclear whether modifier reacted with sMAO.
Table 3 shows the average activity data for each polymerisation reaction. The polymerisation activity is boosted in the case of M=1,4-HO(C6F4)OH, 1,3-HO(C6H4)OH, HO(C6H4)—(C6H4)OH and 2,7-(C10H6)(OH)2 (+29%, +11%, +7% and +6% respectively). The activity data suggest that an electron withdrawing aryl-fluoride modifier is not a strict requirement for a highly active catalyst support.
Using sMMAO(0.025/1,4-HO(C6F4)OH) as the most active support for (EBI)ZrCl2 the effect of increasing [Zr] loading on higher surface area linker modified support was investigated. (EBI)ZrCl2 was immobilised on sMMAO(0.025,HOC5F4OH) at [Al]/[Zr]=200, 150, 100, 50 by swirling at toluene slurry of complex and support at 60° C. In each case complex was fully immobilised as judged by a colourless supernatant solution. This confirms that the high surface area of sMMAO(0.025,HOC6F4OH) enables a higher loading of complex to be immobilised. Slurry phase ethylene polymerisation data are shown in Table 4, showing catalyst activity and productivity increases with [Al]/[Zr], hence a higher complex loading is not beneficial for the catalyst system.
The GPC data for the polyethylene produced by (EBI)ZrCl2 supported on sMMAO(0.025,HOC6F4OH) show that the polyethylene molecular weights decrease with increasing [Zr] complex loading, ranging from 263.0 to 75.1 kg/mol, and polydispersities that are reasonably constant between 4.1<Mw/Mn<3.7, compared with 4.2 for the control sMAO supported catalyst.
A study into the effect of the 5 best performing aromatic di-hydroxy modifying compounds was carried out, as well as pentafluorophenol as a comparison mono-hydroxy modifier, each employing a [M]/[Al] loading of 0.025. A control sMAO support was prepared employing the same synthetic procedure, but without the addition of a modifier compound.
Scanning electron microscopy (SEM) images of the sMMAO(0.025/M) samples with M=1,4-HO(C6F4)OH, 1,4-HO(C6H4)OH and HO(C6H4)—(C6H4)OH are shown in
The complex (EBI)ZrCl2, was immobilised on the surface of linked sMMAO(0.025/M) supports to afford yellow coloured solid below a colourless toluene supernatant solution. The coloured solids were isolated by filtration and dried in vacuo for 3 hours. All immobilised catalysts were characterised by ICP-MS analysis and tested for slurry-phase ethylene polymerisation capability using a 2 litre reactor.
The polymerisation data (Table 5) show that sMMAO(0.025/1,4-HO(C6F4)OH) is the most active support for the (EBI)ZrCl2 immobilised catalyst, showing +40% and +17% increases in activity with respect to the control sMAO and sMMAO(0.025/C6F5OH) supports respectively.
While specific embodiments of the invention have been described herein for the purpose of reference and illustration, various modifications will be apparent to a person skilled in the art without departing from the scope of the invention as defined by the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 1718277.5 | Nov 2017 | GB | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/GB2018/053206 | 11/5/2018 | WO | 00 |
