Catalyst system for multi-stage olefin polymerisation

Abstract

The invention relates to a catalyst system for polymerisation of olefins, comprising a particulate support material carrying a catalyst compound and a cocatalyst compound, wherein the particulate support material has a particle size D50 of ≤ 20 µm, preferably ≤ 15 µm, more preferably ≥ 5 µm and ≤ 15 µm, and preferably is a silica; wherein the particle size D50 is calculated in accordance with ISO 9276-2 (2014), using particle size measurement as performed in accordance with ISO 13320 (2009), wherein the cocatalyst compound is an organoaluminium compound, and wherein the catalyst system comprises ≥ 20.0 wt% of Al atoms, preferably ≥ 20.0 and ≤ 40.0 wt%, more preferably ≥ 20.0 and ≤ 30.0 wt%, with regard to the total weight of the catalyst system. Such catalyst system combines a small particle size of the catalyst system, which is desirable in for example multi-stage olefin polymerisation processes, with high productivity and production of polymers having appropriately high molecular weight.

Description

Catalyst system for multi-stage olefin polymerisation.

[0001] The present invention relates to a catalyst system for olefin polymerisation, in particular wherein the catalyst system is suitable for use in a multi-stage olefin polymerisation process.

[0002] Processes for polymerisation of olefins today account for a majority of the production processes of polymer materials worldwide. A wide array of polyolefin-type materials can be produced by such processes, rendering the produced polymers suitable for a multitude of applications.

[0003] In order to enable the production of desirable polyolefin materials, several types of polymerisation processes have been developed, each targeting production of polymers having a particular molecular architecture, based on a particular formulation of monomer materials that are to be used as reactants. Such polymerisation processes may operate using a single type of monomer material, resulting in homopolymers, or using multiple monomer materials in combination, thereby resulting in copolymers.

[0004] A significant fraction of the olefin polymerisation processes involves the use of catalytic materials to facilitate the polymerisation reactions. Over the last seven decades, multiple catalyst system types have been developed, the most notable of which are the Ziegler-Natta type catalyst systems, the chromium-type catalyst systems, and the single-site type catalyst systems, of which the metallocene-type are particularly well known. Still today, significant work is being done to further develop these catalyst systems to further improve both the polymerisation processes as well as the properties of the polymers that can be produced.

[0005] The most established polyolefin materials are ethylene-based polymers and propylene- based polymers. Catalytic processes for producing these polymers can be performed in gas phase reactions, in slurry reactions, or in solution reactions. In certain advanced polymerisation processes, the olefin polymerisation reaction may be performed using multi-stage processes, in which polymerisation occurs in multiple reactors positioned in series. By appropriate choice of amongst others process conditions, catalyst system and monomer composition that is supplied to each reactor, a polymer can be produced of tailored molecular architecture, thereby serving the requirements of a particular application.

[0006] When applying such multi-stage polymerisation processes, the specifications of the catalyst system that may be employed can be particularly demanding. Aspects that are of notable consideration in developing catalyst systems for such multi-stage olefin polymerisation processes include the size of the catalyst system particles. If the particles are too large, this may lead to excessive polymer particle growth in the later stage(s) of the polymerisation. At the same time, the catalyst system must exhibit sufficient productivity of polymer during the polymerisation reaction, and must produce a polymer having a desirable molecular weight.

[0007] This is now accomplished in accordance with the present invention by catalyst system for polymerisation of olefins, comprising a particulate support material carrying a catalyst compound and a cocatalyst compound, wherein the particulate support material has a particle size D50 of < 20 pm, preferably < 15 pm, more preferably > 5 pm and < 15 pm, and preferably is a silica; wherein the particle size D50 is calculated in accordance with ISO 9276-2 (2014), using particle size measurement as performed in accordance with ISO 13320 (2009), wherein the cocatalyst compound is an organoaluminium compound, and wherein the catalyst system comprises > 20.0 and < 40.0 wt%, more preferably > 25.0 and < 40.0 wt%, more preferably > 20.0 and < 30.0 wt%, even more preferably > 25.0 and < 30.0 wt%, with regard to the total weight of the catalyst system.

[0008] Such catalyst system combines a small particle size, as desirable for certain type of olefin polymerisation processes such as multi-stage polymerisation processes, with high productivity and allows for the production of polyethylene materials of appropriate molecular weight. Such catalyst systems can be used in gas phase, solution and slurry polymerisation reactions.

[0009] The weight fraction of Al atoms in the catalyst system may for example be determined by Inductively Coupled Plasma Atomic Emission Spectrometry (ICP-AES).

[0010] The catalyst compound may for example be selected from a Ziegler-Natta type catalytic compound, a chromium-containing catalytic compound, and a single-site type catalytic compound, such as a metallocene-type catalytic compound. When a metallocene-type compound is used, such compound may for example comprise a zirconium dichloride moiety, a hafnium dichloride moiety, a titanium dichloride moiety, a dimethyl zirconium moiety, a dimethylhafnium moiety, or a dimethyl titanium moiety. Preferably, such metallocene-type compound comprises a zirconium dichloride moiety.

[0011] In certain embodiments, the catalyst compound may be a compound according to formula I:wherein:• Z is a moiety selected from ZrX2, HfX2, or TiX2, wherein X is selected from the group of halogens, alkyls, aryls and aralkyls;• R2 is a bridging moiety;• each R1 , R1’, R3, R3’, R4, R4’, R5 and R5’ are hydrogen or a hydrocarbon moiety comprising 1-20 carbon atoms, or wherein R1 and R5, R5 and R4, R4 and R3, R1’ and R5’, R5’ and R4’, and / or R4’ and R3’ are fused to form a cyclic hydrocarbon moiety comprising 4 to 20 carbon atoms, preferably wherein the cyclic hydrocarbon moiety is a benzene-ring structure comprising moiety, which may contain substituent groups comprising 1-10 carbon atoms.

[0012] In the compound of formula (I), R2 may for example be a moiety selected from:wherein each R6 is individually selected from H or an alkyl moiety comprising 1-10 carbon atoms, preferably wherein each R6 is individually selected from H, CH3 and a benzene moiety, more preferably wherein each R6 is individually selected from H, CH3 and a benzene moiety, and each R6 is the same.

[0013] In the compound of formula (I), Z may for example be selected from TiCI2, ZrCI2, HfCI2, Ti(CH3)2, Zr(CH3)2, and Hf(CH3)2, preferably from ZrCI2and Zr(CH3)2.

[0014] For example, each of R1 , R3, R4 and R5 may be H or CH3.

[0015] For example, R3’ and R4’, or R4’ and R5’, or both R3’ and R4’ as well as R5’ and R1 ’, may be fused to form a cyclic moiety comprising a benzene ring structure. For example, R3 and R4, or R4 and R5, or both R3 and R4 as well as R5 and R1 , may be fused to form a cyclic moiety comprising a benzene ring structure.

[0016] In particular embodiments, the catalyst compound may be a compound selected from: [2,2’-bis(2-indenyl)biphenyl]zirconium dichloride, [2,2’-bis(4,7-dimethyl-2- indenyl)biphenyl]zirconium dichloride, [[1 ,2,3,3a,7a-r|)-2-(1-methylethyl)-1 H-inden-1- yl](dimethylsilylene)[1,2,3,4,5-r|)-2,3,4,5-tetramethyl-2,4-cyclopentadien-1-yl]]zirconium dichloride, diphenylmethylene-(1-cyclopentadienyl)(2,7-di-t-butyl-9-fluorenyl)-zirconium dichloride;[2,2’-bis(2-indenyl)biphenyl] dimethyl zirconium, [2,2’-bis(4,7-dimethyl-2-indenyl)biphenyl] dimethyl zirconium, [[1,2,3,3a,7a-r|)-2-(1-methylethyl)-1 H-inden-1-yl](dimethylsilylene)[1,2,3,4,5- r|)-2,3,4,5-tetramethyl-2,4-cyclopentadien-1-yl]] dimethyl zirconium, diphenylmethylene-(1- cyclopentadienyl)(2,7-di-t-butyl-9-fluorenyl)-dimethyl-zirconium;[2,2’-bis(2-indenyl)biphenyl]hafnium dichloride, [2,2’-bis(4,7-dimethyl-2-indenyl)biphenyl]hafnium dichloride, [[1,2,3,3a,7a-r|)-2-(1-methylethyl)-1H-inden-1-yl](dimethylsilylene)[1 ,2,3,4,5-r|)- 2,3,4,5-tetramethyl-2,4-cyclopentadien-1-yl]]hafnium dichloride, diphenylmethylene-(1- cyclopentadienyl)(2,7-di-t-butyl-9-fluorenyl)-hafnium dichloride;[2,2’-bis(2-indenyl)biphenyl] dimethyl hafnium, [2,2’-bis(4,7-dimethyl-2-indenyl)biphenyl] dimethyl hafnium, [[1 ,2,3,3a,7a-r|)-2-(1-methylethyl)-1 H-inden-1-yl](dimethylsilylene)[1,2,3,4,5- r|)-2,3,4,5-tetramethyl-2,4-cyclopentadien-1-yl]] dimethyl hafnium, diphenylmethylene-(1- cyclopentadienyl)(2,7-di-t-butyl-9-fluorenyl)-dimethyl-hafnium;[2,2’-bis(2-indenyl)biphenyl]titanium dichloride, [2,2’-bis(4,7-dimethyl-2-indenyl)biphenyl]titanium dichloride, [[1 ,2,3,3a,7a-r|)-2-(1-methylethyl)-1 H-inden-1-yl](dimethylsilylene)[1 ,2,3,4,5-r|)-2.3.4.5-tetramethyl-2,4-cyclopentadien-1-yl]]titanium dichloride, diphenylmethylene-(1- cyclopentadienyl)(2,7-di-t-butyl-9-fluorenyl)-titanium dichloride;[2,2’-bis(2-indenyl)biphenyl] dimethyl titanium, [2,2’-bis(4,7-dimethyl-2-indenyl)biphenyl] dimethyl titanium, [[1 ,2,3,3a,7a-r|)-2-(1-methylethyl)-1 H-inden-1-yl](dimethylsilylene)[1 ,2 ,3,4, 5- r|)-2,3,4,5-tetramethyl-2,4-cyclopentadien-1-yl]] dimethyl titanium, and diphenylmethylene-(1- cyclopentadienyl)(2,7-di-t-butyl-9-fluorenyl)-dimethyl-titanium.

[0017] It is particularly preferred that the catalyst compound is a compound selected from [2,2’- bis(2-indenyl)biphenyl]zirconium dichloride, [2,2’-bis(4,7-dimethyl-2-indenyl)biphenyl]zirconium dichloride, [[1 ,2,3,3a,7a-r|)-2-(1-methylethyl)-1 H-inden-1-yl](dimethylsilylene)[1 ,2,3,4,5-r|)-2.3.4.5-tetramethyl-2,4-cyclopentadien-1-yl]]zirconium dichloride, and diphenylmethylene-(1- cyclopentadienyl)(2,7-di-t-butyl-9-fluorenyl)-zirconium dichloride.

[0018] Preferably, the organoaluminium compound is methyl aluminoxane.

[0019] The molar ratio of the cocatalyst to the catalyst compound may for example be in the range of from 1 :1 to 2000:1 , preferably from 50:1 to 500:1.

[0020] The support material may for example be a material selected from silica, alumina, magnesia, titania, zirconia, clay, zeolite, polystyrene, polyethylene, polypropylene, polyvinylchloride, polycarbonate, polyketone, polyvinylalcohol, polymethyl methacrylate, cellulose, graphite, and mixtures thereof. Preferably, the support material is silica.

[0021] The support material, preferably the silica, is preferably a particulate having a specific surface area of 50 to 1000 m2 / g. It is preferred that such silica is dehydrated at a temperature of > 400°C, preferably of > 400°C and < 700°C, more preferably of > 550°C and < 700°C, for a period of > 2 and < 8 hours, preferably of > 4 and < 8 hours. Such dehydration is preferably performed under nitrogen atmosphere.

[0022] In a certain embodiment, the invention also relates to a process for the production of a catalyst system according to the invention, wherein the process involves the steps in this order of:(i) providing a support material, preferably a silica, having a particle size D50 of < 20 pm, preferably < 15 pm, more preferably > 5 pm and < 15 pm to a first vessel; preferably wherein the silica prior to providing it to step (i) has been subjected to dehydration at a temperature of > 400°C for a period of > 2 and < 8 hours;(ii) adding a quantity of a suspension agent to the first vessel;(iii) supplying a quantity of the catalyst compound and a quantity of the cocatalyst to a second vessel, and mixing to obtain an activated catalyst compound;(iv) supplying the activated catalyst compound to the first vessel, and reacting the activated catalyst compound with the silica to obtain the catalyst system.

[0023] Step (iii) of this process may involve the addition of a quantity of a catalyst modifier, preferably wherein the catalyst modifier is a reaction product of a trialkylaluminium compound and an alkylamine compound.

[0024] The preparation of the catalyst system according to the invention may alternatively be performed by contacting the support material, preferably the silica, with the cocatalyst, followed by the addition of the catalyst compound; or by first contacting the catalyst compound with the cocatalyst, followed by addition of the support material; or by first contacting the support material with the cocatalyst, followed by addition of a quantity of a product comprising the catalyst compound that has prior been contacted with a further portion of the cocatalyst.

[0025] Such trialkylaluminium compound may for example be selected from trimethylaluminium, triethylaluminium, tri-isopropyl aluminium and tri-isobutyl aluminium, preferably tri-isobutyl aluminium.

[0026] Such alkylamine compound may for example be selected from cyclohexylamine, octadecylamine and ethylhexylamine, preferably cyclohexylamine.

[0027] Preferably, the trialkylaluminium compound is tri-isobutyl aluminium and the alkylamine compound is cyclohexylamine.

[0028] The invention also relates to a process for polymerisation of olefins wherein the polymerisation is performed in the presence of the catalyst system according to the invention. Preferably, the process is a multi-stage polymerisation process comprising at least a first and a second reactor operating in series.

[0029] The olefins that may be used in the polymerisation process according to the invention may for example be selected from ethylene, propylene, 1-butene, 1-hexene, 1-octene, and combinations thereof. Preferred polymers obtained from the olefin polymerisation process according to the invention are ethylene-based polymers and propylene-based polymers.

[0030] Where the polymerisation is aimed at production of an ethylene-based polymer, the monomer composition that is supplied to the polymerisation process comprises at least 51 wt% of ethylene, with regard to the total weight of the monomers supplied to the process. The monomer composition may comprise at least 51 wt% of ethylene, preferably at least 60 wt%, more preferably at least 70 wt%, or at least 80 wt%, where the remaining fraction comprises one or more of propylene, 1-butene, 1-hexene, or 1-octene, or combinations thereof.

[0031] In embodiments where the process is a multi-stage process for the production of ethylene-based polymers, the monomer composition in each reactor may be different. For example, the monomer composition supplied to the first reactor may consist of ethylene or may consist of ethylene and one or more further olefins selected from propylene, 1-butene, 1-hexene and 1-octene; and the monomer composition supplied to the second reactor may consist of ethylene or may consist of ethylene and one or more further olefins selected from propylene, 1- butene, 1-hexene and 1-octene.

[0032] Where the polymerisation is aimed at production of a propylene-based polymer, the monomer composition that is supplied to the polymerisation process comprises at least 51 wt% of propylene, with regard to the total weight of the monomers supplied to the process. The monomer composition may comprise at least 51 wt% of propylene, preferably at least 60 wt%, more preferably at least 70 wt%, or at least 80 wt%, where the remaining fraction comprises one or more of ethylene, 1-butene, 1-hexene, or 1-octene, or combinations thereof.

[0033] In embodiments where the process is a multi-stage process for the production of propylene-based polymers, the monomer composition in each reactor may be different. For example, the monomer composition supplied to the first reactor may consist of propylene or may consist of propylene and one or more further olefins selected from ethylene, 1-butene, 1- hexene and 1-octene; and the monomer composition supplied to the second reactor may consist of propylene or may consist of propylene and one or more further olefins selected from ethylene, 1-butene, 1-hexene and 1-octene.

[0034] The first reactor may for example be a slurry reactor or a gas phase reactor, and the second reactor may for example be a slurry reactor or a gas-phase reactor. Preferably, the first reactor is a slurry reactor and the second reactor is a slurry reactor, or the first reactor is a slurry reactor and the second reactor is a gas-phase reactor, or the first reactor is a gas-phase reactor and the second reactor is a gas-phase reactor.

[0035] When a polymerisation is performed in a gas-phase reactor, it is preferred that such reactor is operated in condensing mode or in supercondensing mode. It is preferred that a gasphase reactor used in polymerisation according to the present invention is a fluidized bed reactor.

[0036] When a polymerisation is performed in a slurry reactor, it is preferred that such reactor is an autoclave reactor or a loop reactor.

[0037] The invention will now be illustrated by the following non-limiting examples.Materials used in experiments

[0038] The materials that were used in the experiments to demonstrate the invention are listed in the table 1 below.Table 1 : Materials used.

[0039] All materials were handled in a nitrogen atmosphere using either Schlenk techniques or a nitrogen-filled glovebox. Nitrogen, isopentane and other solvents were dried over a bed of molecular sieves. The catalyst systems were prepared under temperature control conditions to within 0.5°C of the set temperatures, in a silicon oil bath with stirring.Preparation of supported metallocene catalyst systems

[0040] A number of supported metallocene catalyst systems were prepared according to the procedure set out below. Details of quantities and nature of materials used and content of the metals Zr and Al in the catalyst systems are presented in table 2.

[0041] The support was pre-dehydrated at 600°C for 4 hours. A given amount of the predehydrated support was charged into a 100 ml two-neck Schlenk flask in a glovebox under nitrogen atmosphere, followed by addition of 15 ml toluene. After shaking, a silica suspension was obtained. A given amount of the metallocene catalyst compound was activated by mixing with a given amount of the cocatalyst in a 25 ml vial at room temperature for 10 min in the glovebox, also under nitrogen atmosphere. The quantity of metallocene catalyst compound was chosen to arrive at a desired wt% of Zr in the catalyst system. The thus obtained activated metallocene was transferred into the silica suspension. 3.64 mg of CHA and 7.28 mg of TIBAL were mixed in 10 ml of toluene in another 25 ml vial at room temperature in the glovebox and then transferred into the suspension. This final mixture was heated to 95°C and maintained at that temperature for 5 hours. Subsequently, the product was dried at 75°C under vacuum to obtain the supported catalyst system, which was isolated as a free-flowing powder.Table 2: Composition of catalyst systems

[0042] The catalyst systems A1-A4 were prepared using the larger silica S1, thus resulting in catalyst system particles of larger particle size, compared to catalyst systems A5-A12, which were prepared using the smaller silica S2.Polymerisation experiments

[0043] Using the catalyst systems A1-A12, a set of polymerisation experiments was conducted to establish the performance of each of the catalyst systems in ethylene polymerisation.

[0044] A 1.6 I stainless steel reactor vessel equipped with a helical stirrer and a heating / cooling control unit was heated to 110°C at a nitrogen flow rate of 100 g / h for 2 hours. After that, the reactor was pressure purged with nitrogen, followed by a purge with ethylene. This purging cycle was repeated three times.

[0045] The reactor was then cooled to 88 °C under ethylene pressurised to 10 bar.

[0046] For the gas-phase polymerisation experiments B1-B12, after venting, 4 ml of AXION® PA 4276 was added via a cocatalyst injection pump. Nitrogen was introduced to maintain a nitrogen pressure of 8 bar. Ethylene was then introduced to the reactor under control of massflow parameters to maintain an ethylene pressure in the reactor of 10 bar. Upon reaching a stable level of temperature and pressure, 40 mg of the catalyst system was injected via a catalyst injection pump and the reaction started. After 1 hour, the ethylene supply was discontinued and the reactor was cooled to 40°C. The reactor was opened after venting. The polyethylene product was collected to a sample tray and dried at ambient temperature under atmospheric pressure.

[0047] In the case of the slurry polymerisation experiments B13-B16, after venting, 200 ml of isopentane was charged via a cocatalyst injection pump followed by addition of 4 ml of diluted AXION® PA 4276. Nitrogen was introduced to maintain a nitrogen pressure of 3 bar. Ethylene was then introduced to the reactor under control of mass flow parameters to maintain an ethylene pressure in the reactor of 10 bar. Upon reaching a stable level of temperature and pressure, 40 mg of catalyst was injected via a catalyst injection pump and the reaction started. After 1 hour, the ethylene supply was discontinued and the reactor was cooled to 40°C. The reactor was opened after venting. The polyethylene product was collected to a sample tray and dried at ambient temperature under atmospheric pressure.

[0048] The polymerization results are presented in Table 3 below.Table 3: Results of polymerisation experiments

[0049] In this table, the PE yield is expressed as weight of the polyethylene obtained in the experiment, in g; the productivity is defined as the weight of polyethylene obtained per weight unit of catalyst system supplied, in g PE / g Cat. The Mnis the number average molecular weight, and Mwthe weight average molecular weight, both expressed in kg / mol, and determined in accordance with ASTM D6474 (2012). Mw / Mnis the ratio of Mwand Mn, dimensionless, indicating the molecular weight distribution.

[0050] From table 3, it can be observed that a catalyst system having relatively small particle size, as desirable for certain type of olefin polymerisation processes such as multi-stage polymerisation processes, that still have high productivity and allow for the production of polyethylene materials of appropriate molecular weight can be achieved by applying an increased Al content. Such catalyst systems can be used in both gas phase and slurry polymerisation reactions.

Claims

Claims1. Catalyst system for polymerisation of olefins, comprising a particulate support material carrying a catalyst compound and a cocatalyst compound, wherein the particulate support material has a particle size D50 of < 20 pm, preferably < 15 pm, more preferably > 5 pm and < 15 pm, and preferably is a silica; wherein the particle size D50 is calculated in accordance with ISO 9276-2 (2014), using particle size measurement as performed in accordance with ISO 13320 (2009); wherein the cocatalyst compound is an organoaluminium compound; and wherein the catalyst system comprises > 20.0 wt% of Al atoms, preferably > 20.0 and < 40.0 wt%, more preferably > 25.0 and < 40.0 wt%, more preferably > 20.0 and < 30.0 wt%, even more preferably > 25.0 and < 30.0 wt%, with regard to the total weight of the catalyst system.

2. Catalyst system according to claim 1 , wherein the catalyst compound is selected from a Ziegler-Natta type catalytic compound, a chromium-containing catalytic compound, and a single-site type catalytic compound, such as a metallocene-type catalytic compound.

3. Catalyst system according to any one of claims 1-2, wherein the catalyst compound is a metallocene-type catalytic compound, preferably a zirconium dichloride-containing compound.

4. Catalyst system according to any one of claims 1-3, wherein the catalyst compound is a compound according to formula I:wherein:Z is a moiety selected from ZrX2, HfX2, or TiX2, wherein X is selected from the group of halogens, alkyls, aryls and aralkyls;R2 is a bridging moiety; each R1 , R1’, R3, R3’, R4, R4’, R5 and R5’ are hydrogen or a hydrocarbon moiety comprising 1-20 carbon atoms, or wherein R1 and R5, R5 and R4, R4 and R3, R1’ and R5’, R5’ and R4’, and / or R4’ and R3’ are fused to form a cyclic hydrocarbon moiety comprising 4 to 20 carbon atoms, preferably wherein the cyclic hydrocarbon moiety is a benzene-ring structure comprising moiety, which may contain substituent groups comprising 1-10 carbon atoms.

5. Catalyst system according to claim 4, wherein R2 is a moiety selected from:wherein each R6 is individually selected from H or an alkyl moiety comprising 1-10 carbon atoms, preferably wherein each R6 is individually selected from H, CH3 and a benzene moiety, more preferably wherein each R6 is individually selected from H, CH3and a benzene moiety, and each R6 is the same.

6. Catalyst system according to any one of claims 4-5, wherein Z is selected from TiCI2, ZrCI2, HfCI2, Ti(CH3)2, Zr(CH3)2, and Hf(CH3)2, preferably from ZrCI2and Zr(CH3)2.

7. Catalyst system according to any one of claims 4-6, wherein:• each of R1 , R3, R4 and R5 are H or CH3; and / or• R3’ and R4’, or R4’ and R5’, or both R3’ and R4’ as well as R5’ and R1’, are fused to form a cyclic moiety comprising a benzene ring structure; and / or• R3 and R4, or R4 and R5, or both R3 and R4 as well as R5 and R1 , are fused to form a cyclic moiety comprising a benzene ring structure.

8. Catalyst system according to any one of claims 1-7, wherein the catalyst compound is a compound selected from: [2,2’-bis(2-indenyl)biphenyl]zirconium dichloride, [2,2’-bis(4,7-dimethyl-2- indenyl)biphenyl]zirconium dichloride, [[1,2,3,3a,7a-r|)-2-(1-methylethyl)-1H-inden-1- yl](dimethylsilylene)[1 ,2,3,4,5-r|)-2,3,4,5-tetramethyl-2,4-cyclopentadien-1-yl]]zirconium dichloride, diphenylmethylene-(1-cyclopentadienyl)(2,7-di-t-butyl-9-fluorenyl)-zirconium dichloride;[2,2’-bis(2-indenyl)biphenyl] dimethyl zirconium, [2,2’-bis(4,7-dimethyl-2-indenyl)biphenyl] dimethyl zirconium, [[1 ,2,3,3a,7a-r|)-2-(1-methylethyl)-1 H-inden-1- yl](dimethylsilylene)[1 ,2,3,4,5-r|)-2,3,4,5-tetramethyl-2,4-cyclopentadien-1-yl]] dimethyl zirconium, diphenylmethylene-(1-cyclopentadienyl)(2,7-di-t-butyl-9-fluorenyl)-dimethyl- zirconium;[2,2’-bis(2-indenyl)biphenyl]hafnium dichloride, [2,2’-bis(4,7-dimethyl-2- indenyl)biphenyl]hafnium dichloride, [[1,2,3,3a,7a-r|)-2-(1-methylethyl)-1H-inden-1- yl](dimethylsilylene)[1 ,2,3,4,5-r|)-2,3,4,5-tetramethyl-2,4-cyclopentadien-1-yl]]hafnium dichloride, diphenylmethylene-(1-cyclopentadienyl)(2,7-di-t-butyl-9-fluorenyl)-hafnium dichloride;[2,2’-bis(2-indenyl)biphenyl] dimethyl hafnium, [2,2’-bis(4,7-dimethyl-2-indenyl)biphenyl] dimethyl hafnium, [[1,2,3,3a,7a-r|)-2-(1-methylethyl)-1 H-inden-1- yl](dimethylsilylene)[1 ,2,3,4,5-r|)-2,3,4,5-tetramethyl-2,4-cyclopentadien-1-yl]] dimethyl hafnium, diphenylmethylene-(1-cyclopentadienyl)(2,7-di-t-butyl-9-fluorenyl)-dimethyl- hafnium;[2,2’-bis(2-indenyl)biphenyl]titanium dichloride, [2,2’-bis(4,7-dimethyl-2- indenyl)biphenyl]titanium dichloride, [[1,2,3,3a,7a-r|)-2-(1-methylethyl)-1 H-inden-1- yl](dimethylsilylene)[1 ,2,3,4,5-r|)-2,3,4,5-tetramethyl-2,4-cyclopentadien-1-yl]]titanium dichloride, diphenylmethylene-(1-cyclopentadienyl)(2,7-di-t-butyl-9-fluorenyl)-titanium dichloride;[2,2’-bis(2-indenyl)biphenyl] dimethyl titanium, [2,2’-bis(4,7-dimethyl-2-indenyl)biphenyl] dimethyl titanium, [[1 ,2,3,3a,7a-r|)-2-(1-methylethyl)-1 H-inden-1- yl](dimethylsilylene)[1 ,2,3,4,5-r|)-2,3,4,5-tetramethyl-2,4-cyclopentadien-1-yl]] dimethyl titanium, and diphenylmethylene-(1-cyclopentadienyl)(2,7-di-t-butyl-9-fluorenyl)-dimethyl- titanium; preferably from [2,2’-bis(2-indenyl)biphenyl]zirconium dichloride, [2,2’-bis(4,7-dimethyl-2- indenyl)biphenyl]zirconium dichloride, [[1,2,3,3a,7a-r|)-2-(1-methylethyl)-1H-inden-1-yl](dimethylsilylene)[1 ,2,3,4,5-r|)-2,3,4,5-tetramethyl-2,4-cyclopentadien-1-yl]]zirconium dichloride, and diphenylmethylene-(1-cyclopentadienyl)(2,7-di-t-butyl-9-fluorenyl)- zirconium dichloride.

9. Catalyst system according to any one of claims 1-8, wherein the organoaluminium compound is methyl aluminoxane.

10. Process for production of a catalyst system according to any one of claims 1-9, wherein the process involves the steps in this order of:(i) providing a support material, preferably a silica, having a particle size D50 of < 20 pm, preferably < 15 pm, more preferably > 5 pm and < 15 pm to a first vessel; preferably wherein the silica prior to providing it to step (i) has been subjected to dehydration at a temperature of > 400°C for a period of > 2 and < 8 hours;(ii) adding a quantity of a suspension agent to the first vessel;(iii) supplying a quantity of the catalyst compound and a quantity of the cocatalyst to a second vessel, and mixing to obtain an activated catalyst compound;(iv) supplying the activated catalyst compound to the first vessel, and reacting the activated catalyst compound with the silica to obtain the catalyst system.11 . Process according to claim 10, wherein step (iii) further involves the addition of a quantity of a catalyst modifier, preferably wherein the catalyst modifier is a reaction product of a trialkylaluminium compound and an alkylamine compound.

12. Process according to claim 11 , wherein the trialkylaluminium compound is selected from trimethylaluminium, triethylaluminium, tri-isopropyl aluminium and tri-isobutyl aluminium, preferably tri-isobutyl aluminium; and / or wherein the alkylamine compound is selected from cyclohexylamine, octadecylamine and ethylhexylamine, preferably cyclohexylamine.

13. Process for polymerisation of olefins wherein the polymerisation is performed in the presence of the catalyst system according to any one of claims 1-9, preferably wherein the process is a multi-stage polymerisation process comprising at least a first and a second reactor operating in series.

14. Process according to claim 13, wherein the first reactor is a slurry reactor or a gas phase reactor, and wherein the second reactor is a slurry reactor or a gas-phase reactor.

15. Process according to any one of claims 13-14, wherein the first reactor is a slurry reactor and the second reactor is a slurry reactor, or wherein the first reactor is a slurry reactor and the second reactor is a gas-phase reactor, or wherein the first reactor is a gas-phase reactor and the second reactor is a gas-phase reactor.

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