WO2025201795A1

WO2025201795A1 - Catalyst system for use in olefin polymerisation

Info

Publication number: WO2025201795A1
Application number: PCT/EP2025/055575
Authority: WO
Inventors: Lidong LI; Salah AL HUBISH
Original assignee: SABIC Global Technologies BV
Current assignee: SABIC Global Technologies BV
Priority date: 2024-03-26
Filing date: 2025-02-28
Publication date: 2025-10-02
Anticipated expiration: 2026-09-26

Abstract

The present invention relates to a bimetallic catalyst system for olefin polymerisation comprising a first catalyst component A and a second catalyst component B, wherein each of A and B are bridged metallocene catalyst compounds, wherein one of A and B comprises a 1,2-phenylene bridge and wherein the other of A and B comprises a 2,2'-biphenyl bridge. Such catalyst system allows for the copolymerisation of ethylene with reversed comonomer incorporation.

Description

CATALYST SYSTEM FOR USE IN OLEFIN POLYMERISATION

[0001] The present invention relates to a catalyst system for olefin polymerisation.

[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. Ongoing development of catalyst systems continues to results in improvements in both production processes as well as in material properties of polyolefin materials. A desire persists to further develop catalyst systems to arrive at more beneficial processes and polyolefin materials.

[0006] A particular relevant species of polyolefin materials are ethylene-based copolymers. Such copolymers are produced by reaction of ethylene with one or more further olefinic comonomers, particularly with monoolefinic linear alpha-olefins. Typical comonomers used include 1 -butene, 1 -hexene and 1 -octene. Typically, the ethylene is present as majority reactant in terms of weight, and the comonomer(s) as minority component.

[0007] In such copolymers, the ethylene molecules and the comonomer molecules react to form polymeric molecules wherein the ethylene-based moieties and the comonomer-based moieties are distributed in certain manner along the polymer chains. The comonomer-based moieties form certain branches to the polymer chain, resulting from the part of the molecule that is trailing the alpha-olefinic unsaturated bond that reacts into the polymer chain. Such branches to the polymer chain that are induced by comonomer incorporation are referred to as short-chain branches, also referred to herein as SCB.

[0008] The distribution of incorporation of SCB in ethylene-based copolymers can vary, and can be affected by the polymerisation conditions and choice of catalyst system. In addition, in catalytic ethylene polymerisation, the length of the polymer chains follows a certain distribution; certain longer chains may be formed, as well as certain shorter chain, as compared to the average polymer chain length.

[0009] It may occur that a high concentration of SCB occurs in the shorter chains of the distribution, as compared to the average, or in the longer chains. The short-chain branching in an ethylene-based polymer is typically expressed as the number of SCB per 1,000 (one- thousand) carbon atoms in the polymer chain.

[0010] A particular architecture of ethylene-based polymer molecules is that wherein the concentration of SCB in the longer chain fraction of the polymer composition is higher than in the shorter chain fraction. Such architecture is referred to as reversed comonomer incorporation; a relatively lower incorporation in the shorter chains, versus a relatively higher incorporation in the longer chains. A polymer having such architecture may be referred to as a reversed CCD polymer; wherein CCD is to be understood to be the chemical composition distribution.

[0011] Such reversed CCD ethylene-based polymers may have certain desirable properties, including a good balance of stiffness and toughness. Without being bound by any theory, it is considered that when the ethylene-based polymer has a reversed CCD, the low molecular weight fraction, being the fraction having the shorter chains, has a higher degree of crystallinity, which may attribute to improved stiffness. The presence of a greater amount of SCB in the longer chains is believed to attribute to higher toughness, as the presence of more chain branches is considered to allow for more intermolecular ties or entanglements.

[0012] Therefore, there is a desire to have access to such reverse CCD ethylene-based polymer materials.

[0013] The production of such polymers may for example be performed using a cascade reactor technology, or via particularly engineered catalyst systems. Having access to suitable catalyst systems that can introduce an appropriate reverse CCD comonomer incorporation in one single polymerisation reactor is particularly desirable, as this clearly is beneficial for process economics. An ongoing desire exists to develop such catalyst systems, which is now addressed in accordance with the present invention by a catalyst system comprising a first catalyst component A and a second catalyst component B, wherein component A is a component according to formula (I): and wherein component B is a component according to formula (II): wherein R1 and R2 are different and preferably selected from wherein each R12 is individually selected from H or an alkyl moiety comprising 1-10 carbon atoms, preferably wherein each R12 is individually selected from H, CH3 and a benzene moiety, more preferably wherein each R12 is individually selected from H, CH3 and a benzene moiety and each R12 is the same; wherein R3 is a moiety selected from ZrX₂, HfX₂ and TiX₂, wherein X is selected from the group of halogens, alkyls, aryls and aralkyls; wherein each R4-R11 are hydrogen or a hydrocarbon moiety comprising 1 to 20 carbon atoms, or wherein R4 and R5, R5 and R6, R8 and R9, and/or R9 and R10 are fused to form a cyclic hydrocarbon moiety comprising 4 to 20 carbon atoms, preferably wherein the cyclic hydrocarbon moiety is a cyclohexene-ring or benzene-ring comprising moiety, which may contain substituent groups comprising 1-10 carbon atoms.

[0014] It is preferred that the bridging moiety R1 comprises at least one aryl group.

[0015] It is preferred that each R3 is selected from TiCh, ZrCI₂, HfCh, Ti(CH3)2, Zr(CH3)2, and Hf(CH3)2, preferably from ZrCh and Zr(CHs)2.

[0016] In a preferred embodiment, each R1 and R2 is selected from

[0017] It is further preferred that the component A is according to formula (III): wherein each R4, R7, R8 and R11 is individually selected to be H, CH₃, t-butyl, or phenyl; preferably wherein R1 is 2,2’-biphenyl.

[0018] The component A may for example be a component selected from [2.2'-bis(2- indenyl)biphenyl]-zirconiumdichloride, [2,2'-bis(2-indenyl)biphenyl]-hafniumdichloride, [2.2 - bis(2-(4,7-dimethyl)indenyl)biphenyl]-zirconiumdichloride, [2,2'-bis(2-(4,7- dimethyl)indenyl)biphenyl]-hafniumdichloride, [2.2'-bis(2-(4,5,6,7-tetrahydro)indenyl)biphenyl]- zirconiumdichloride, [2,2'-bis(2-(4,5,6,7-tetrahydro)indenyl)biphenyl]-hafniumdichloride, [2.2 - bis(2-(5-fluoro)indenyl)biphenyl]-zirconiumdichloride, [2,2'-bis(2-(5-fluoro)indenyl)biphenyl]- hafniumdichloride, [2.2'-bis(2-(2-fluoro)indenyl)biphenyl]-zirconiumdichloride, [2,2'-bis(2-(2- fluoro)indenyl)biphenyl]-hafniumdichloride, [2.2'-bis(2-(4,6-diisopropyl)indenyl)biphenyl]- zirconiumdichloride, [2,2'-bis(2-(4,6-diisopropyl)indenyl)biphenyl]hafniumdichloride, [2.2'-bis(2- (4,6-dimethyl)indenyl)biphenyl]-zirconiumdichloride, [2,2'-bis(2-(4,6-dimethyl)indenyl)biphenyl]- hafniumdichloride, [2.2'-bis(2-(5,6-cyclopentyl)indenyl)biphenyl]-zirconiumdichloride, and [2,2'- bis(2-(5,6-cyclopentyl)indenyl)biphenyl]-hafniumdichloride.

[0019] It is particularly preferred that the component A is [2.2'-bis(2-(4,5,6,7- tetrahydro)indenyl)biphenyl]-zirconium(IV) dichloride.

[0020] In a further embodiment, the component B is according to formula (IV): wherein each R4, R5, R6, R7 and R8 is individually selected to be H, CH3, t-butyl, or phenyl, preferably wherein each R4, R5 and R6 is CH₃, and preferably wherein R7 and/or R8 is phenyl; preferably wherein R2 is 1,2-phenylene.

[0021] The component B may for example be a component selected from 1 ,2-phenylene-[(2- methyl-1-lndenyl)(1-phenyl-2-benz[e]indenyl)]-zirconium(IV) dichloride, 1,2-phenylene-[(2- methyl-1-lndenyl)(1-phenyl-2-benz[e]indenyl)]-hafnium(IV) dichloride, 1 ,2-phenylene-[(1-methyl- 3-phenyl-2-lndenyl)(4,7-dimethyl-2-indenyl)]-zirconium(IV) dichloride, 1 ,2-phenylene-[(1-methyl- 3-phenyl-2-lndenyl)(4,7-dimethyl-2-indenyl)]-hafnium(IV) dichloride, 1 ,2-phenylene-[(2,4,7- trimethyl- 1 -I ndenyl)( 1 -phenyl-2-indenyl)]-zi rconium(IV) dichloride, 1 ,2-phenylene-[(2,4,7- trimethyl-1-lndenyl)(1-phenyl-2-indenyl)]-hafnium(IV) dichloride, 1 ,2-phenylene-[(3,4- dimethylcyclopentadienyl)(1 ,3-dimethyl-2-indenyl)]-zirconium(IV) dichloride, 1 ,2-phenylene- [(3,4-dimethylcyclopentadienyl)(1 ,3-dimethyl-2-indenyl)]-hafnium(IV) dichloride, 1 ,2-phenylene- [(3,4-diphenylcyclopentadienyl)(1 ,3-dimethyl-2-indenyl)]-zirconium(IV) dichloride, 1 ,2- phenylene-[(3,4-diphenylcyclopentadienyl)(1 ,3-dimethyl-2-indenyl)]-hafnium(IV) dichloride, 1 ,2- phenylene-[(tetramethylcyclopentadienyl)(1-phenyl-2-indenyl)]-zirconium(IV) dichloride, and 1 ,2- phenylene-[(tetramethylcyclopentadienyl)(1-phenyl-2-indenyl)]-hafnium(IV) dichloride.

[0022] It is particularly preferred that the component B is 1 ,2-phenylene-[(2,4,7-trimethyl-1- lndenyl)(1-phenyl-2-indenyl)]-zirconium(IV) dichloride.

[0023] The molar ratio of component A to component B may for example be from 0.1 to 100, preferably from 0.1 to 10, more preferably from 0.1 to 5.0, more preferably from 0.1 to 4.0, more preferably from 0.2 to 1.5.

[0024] It is further preferred that the component A and the component B are carried on a support, preferably wherein both components are carried on the same support, preferably wherein the support is selected from silica, alumina, magnesia, titania, zirconia, clay, zeolite, graphite, and polymeric particles, preferably silica.

[0025] The support material, preferably the silica, is preferably a particulate having a specific surface area of 50 to 1000 m²/g. Preferably, the silica has a pore volume of 0.5 to 3.0 g/cm³. The silica may for example have a mean particle diameter of 3 to 20 pm. A silica having such mean particle diameter may be suitable for use in catalyst systems that are to be use in solution polymerisation processes. The silica may for example have a mean particle diameter of 30 to 100 pm. A silica having such mean particle diameter may be suitable for use in catalyst systems that are to be use in gas-phase polymerisation processes. The silica may for example have a mean particle diameter of 5 to 80 pm. A silica having such mean particle diameter may be suitable for use in catalyst systems that are to be use in slurry polymerisation processes.

[0026] 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. [0027] In a preferred embodiment, the catalyst system comprises a cocatalyst. The cocatalyst may be an organoaluminium compound or a non-coordinating anionic compound. For example, the cocatalyst may be methylaluminoxane, perfluorophenylborane, triethylammonium tetrakis(pentafluorophenyl)borate, triphenylcarbenium tetrakis(pentafluorophenyl)borate, trimethylsilyl tetrakis(pentafluorophenyl)borate, 1-pentafluorophenyl-1 ,4-dihydroboratabenzene, tributylammonium 1 ,4-bis(pentafluorophenyl)boratabenzene, or triphenylcarbenium 1- methylboratabenzene. Preferably, the cocatalyst is methyl aluminoxane.

[0028] In such embodiments were an organoaluminium compound is used as cocatalyst, the molar ratio of the cocatalyst to the sum of the components A and B may for example be from 1 to 2000, preferably from 50 to 500.

[0029] In a particular embodiment, the catalyst system may for example comprise > 6.0 and < 40.0 wt% of Al, with regard to the total weight of the catalyst system, preferably > 7.0 and < 35.0 wt%, more preferably > 10.0 and < 30.0 wt%.

[0030] In a particular embodiment, the catalyst system may for example comprise > 0.10 and < 1.00 wt% of the sum of Zr, Hf and Ti, with regard tot the total weight of the catalyst system, preferably > 0.15 and < 0.50 wt%, more preferably > 0.15 and < 0.30 wt%.

[0031] The invention also relates to a process for producing certain embodiments of the catalyst system, wherein the process involves the steps in this order of:

(i) treating the support with the cocatalyst, followed by

(ii) addition of the components A and B; or

(i) treating the components A and B with the cocatalyst, followed by

(ii) addition of the support; or

(i) treating the components A and B with the cocatalyst to obtain activated components A and B;

(ii) treating the support with the cocatalyst to obtain an activated support; and

(iii) combining the activated support with the activated components A and B. [0032] The invention also relates to a process for polymerisation of a reaction mixture comprising ethylene and/or propylene using the catalyst system. Such process may for example be an ethylene homo- or copolymerisation process or a propylene homo- or copolymerisation process. For example, such polymerisation process may be a copolymerisation process of ethylene with one or more comonomers selected from 1 -butene, 1 -hexene and 1 -octene. For example, such polymerisation process may be a copolymerisation process of propylene with one or more copolymers selected from ethylene, 1 -butene and 1 -hexene. Homopolymers or copolymers of ethylene produced according to such process may for example have a density of from 0.860 to 0.970 g/cm³.

[0033] Such polymerisation process may for example be a solution process, a gas-phase process, a slurry process, or a bulk process. Such slurry polymerisation process may for example be performed in an autoclave or a loop reactor. Such gas-phase process may for example be performed in a fluidised bed reactor, for example operating in condensing or supercondensing mode.

[0034] The invention will now be illustrated by the following non-limiting examples.

[0035] In the context of the present invention, the below materials were used in the experiments.

Table 1 : Materials used. [0036] 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.

Synthesis of MET-B

[0037] [synthesis cat205 to be described]

[0038] To obtain MET-B, a synthesis was performed involving a first step of reacting 2', 5'- dimethylpropiophenone with 2-bromobenzaldehyde to obtain 3-(2-bromophenyl)-2-methyl-1- (2,5-dimethylphenyl)-2-propene-1-one (compound A):

[0039] The compound A was reacted with polyphosphoric acid to obtain 3(2-bromophenyl)- 2,4,7-trimethyl-2,3-dihydro-1 H-inden-1-one (compound B):

[0040] The compound B was reacted with NaBH4 to obtain 1-(2-bromophenyl)-2,4,7-trimethyl- 1H-indene (compound C):

[0041] The compound C was reacted with 4,4,5,5-tetramethyl-2-(3-phenyl-1 H-inden-2-yl)-1 ,3,2- dioxaborolane in CS2CO3 and dioxin, with addition of Pd(PPha)4 to obtain 2,4,7-trimethyl-1-(2-(3- phenyl)-1 H-inden-2-yl)phenyl)-1 H-indene (compound D):

[0042] The compound D was reacted with n-butyllithium, Zr(NMe2)Cl2(THF)2 and MeSiCh in toluene to obtain 1 ,2-phenylene-[(2,4,7-trimethyl-1-lndenyl)(1-phenyl-2-indenyl)]-zirconium(IV) dichloride, the catalyst compound MET-B. Preparation of supported metallocene catalyst systems

[0043] 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.

[0044] The support was pre-dehydrated at 600°C for 4 hours. An amount of 2.5 g 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. Given amounts of the metallocene catalyst compounds as listed in table 2 were activated by mixing with 12.4 ml of the cocatalyst in a 25 ml vial at room temperature for 10 min in the glovebox, also under nitrogen atmosphere. The thus obtained activated metallocenes were 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. The Zr and Al contents in the catalyst systems were 0.18 wt% and 14.0 wt%, respectively.

Table 2: Composition of catalyst systems

Polymerisation experiments

[0045] Using the catalyst systems A1-A3, a set of polymerisation experiments was conducted to establish the performance of each of the catalyst systems in ethylene polymerisation.

[0046] 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.

[0047] The reactor was then cooled to 88 °C under ethylene pressurised to 10 bar. After venting, 4 ml of SC was added via a cocatalyst injection pump. Nitrogen was introduced to maintain a nitrogen pressure of 8 bar. Ethylene and 1 -hexene with a given molar ratio as shown in table 3 were then introduced to the reactor under control of mass flow parameters to maintain a pressure of ethylene and 1 -hexene 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. During the reaction, ethylene and 1 -hexene were kept at given molar ratio as shown in table 3 via control of mass flow parameters. After 1 hour, the ethylene and 1 -hexene 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. It can be seen that the catalyst productivities vary as function of the catalyst system and of the ratio of 1 -hexene to ethylene added to the reactor.

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. C6=/C2= indicated the 1-hexene/ethylene molar ratio. [0050] Product characterisation was performed on the obtained products to obtain density and molecular weight characteristics M_n, M_w and M_z. The M_n is the number average molecular weight, M_w the weight average molecular weight, and M_z is the z-average molecular weight, each expressed in kg/mol, and determined in accordance with ASTM D6474 (2012). M_w/M_n is the ratio of M_w and M_n, dimensionless, indicating the molecular weight distribution M_z/M_w is the ratio of M_z and M_w, also dimensionless. Density was determined in accordance with the method of ASTM D792 (2013), and expressed in g/cm³. The results are presented in table 4 below. Table 4: Polymer characteristics

[0051] The molecular weight distributions of the polymers were determined by gel permeation chromatography (GPC) recorded on an Agilent PL-GPC 220 chromatograph at 150°C using 1,2,4-trichlorobenzene as diluent, equipped with a PL BV-400 viscometer and infrared detectors to collect the signal for molecular weights. The results are summarized in Table 4. [0052] The comonomer distributions are displayed in Figures 1-18. It can be seen that a reversed CCD distribution is observed for each experiment and it varies as a function of molar ratio of 1-hexene to ethylene added in the reactor. The GPC data were deconvoluted to achieve the most probable fit for two MW components via utilizing the method described in the literature (Niket Sharma and Y. A. Liu, Ind. Eng. Chem. Res. 2019, 58, 14209-14226). The results are summarized in Table 5. It is apparent that the MW and fraction weight percentage of each component vary as a function of molar ratio of 1-hexene to ethylene added in the reactor. Table 5: Characteristics of low and high molecular weight fractions [0053] Crystallization elution fractionation (CEF) analysis was conducted on a Polymer Char CEF instrument. The samples were first dissolved in 1,2,4 trichlorobenzene (TCB) in 1 mg/ml at 160 °C for 1 hour. TCB was stabilized by 1000 ppm of BHT. The polymer solution was injected into the system and pumped through the CEF column. The column was cooled down to 35 °C at a cooling rate of 2 °C/min under continuous TCB flow at a flow rate of 0.05 ml/min. At the end of the cooling cycle, the temperature was kept constant for 5 min. Finally, the samples were eluted out by TCB flow at a flow rate of 1 ml/min, and in the meantime the column was heated to 160 °C at a rate of 4 °C/min. The results are presented in Figures 19-21. It can be seen that the CEF profile varies as a function of molar ratio of 1 -hexene to ethylene added in the reactor.

[0054] Further polymerisation experiments were conducted wherein a reaction mixture comprising ethylene and 1-hexene as comonomer was polymerised in the presence of hydrogen.

[0055] 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.

[0056] The reactor was then cooled to 88 °C under ethylene pressurised to 10 bar. After venting, 4 ml of SC was added via a cocatalyst injection pump. A given amount of hydrogen as presented in table 6 was injected under control of mass flow parameters. Nitrogen was introduced to maintain a nitrogen pressure of 8 bar. Ethylene and 1-hexene with a molar ratio 1- hexene/ethylene of 0.12 were then introduced to the reactor under control of mass flow parameters to maintain a pressure of ethylene and 1-hexene 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. During the reaction, ethylene and 1- hexene were kept at molar ratio of 0.12 via control of mass flow parameters. After 1 hour, the ethylene and 1-hexene 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.

[0057] The polymerisation results are summarised in table 6. It is apparent that the catalyst productivity varies as a function of the hydrogen content added to the reactor. The molecular weight characteristics and the density of the polymers are presented in table 7. It can be observed that the molecular weight decreased with increasing hydrogen content. The comonomer distributions are presented in figures 22-24. It can be seen that a reversed CCD is achieved for each experiment. Table 8 lists the deconvolution results. Table 6: Results of polymerisation experiments

[0058] In this table, H2 is the quantity of hydrogen supplied in mg. H2/C2= is the molar ratio hydrogen/ethylene. Table 7: Polymer characteristics

Table 8: Characteristics of low and high molecular weight fractions

Claims

1. Catalyst system comprising a first catalyst component A and a second catalyst component B, wherein component A is a component according to formula (I): and wherein component B is a component according to formula (II): wherein R1 and R2 are different and preferably selected from wherein each R12 is individually selected from H or an alkyl moiety comprising 1-10 carbon atoms, preferably wherein each R12 is individually selected from H, CH₃ and a benzene moiety, more preferably wherein each R12 is individually selected from H, CH₃ and a benzene moiety and each R12 is the same; wherein R3 is a moiety selected from ZrX2, HfX2 and TiX2, wherein X is selected from the group of halogens, alkyls, aryls and aralkyls; wherein each R4-R11 are hydrogen or a hydrocarbon moiety comprising 1 to 20 carbon atoms, or wherein R4 and R5, R5 and R6, R8 and R9, and/or R9 and R10 are fused to form a cyclic hydrocarbon moiety comprising 4 to 20 carbon atoms, preferably wherein the cyclic hydrocarbon moiety is a cyclohexene-ring or benzene-ring comprising moiety, which may contain substituent groups comprising 1-10 carbon atoms.

2. Catalyst system according to claim 1 , wherein each R3 is selected from TiCh, ZrCh, HfC ,

Ti(CHa)2, Zr(CHs)2, and Hf(CHa)2, preferably from ZrCh and Zr(CHs)2.

3. Catalyst system according to any one of claims 1-2, wherein each R1 and R2 is selected from

4. Catalyst system according to any one of claims 1-3, wherein the component A is according to formula (III): wherein each R4, R7, R8 and R11 is individually selected to be H, CH3, t-butyl, or phenyl; preferably wherein R1 is 2,2’-biphenyl.

5. Catalyst system according to claim 4, wherein the component A is [2.2'-bis(2-(4, 5,6,7- tetrahydro)indenyl)biphenyl]-zirconium(IV) dichloride.

6. Catalyst system according to any one of claims 1-5, wherein the component B is according to formula (IV): wherein each R4, R5, R6, R7 and R8 is individually selected to be H, CH3, t-butyl, or phenyl, preferably wherein each R4, R5 and R6 is CH3, and preferably wherein R7 and/or R8 is phenyl; preferably wherein R2 is 1 ,2-phenylene.

7. Catalyst system according to claim 6, wherein component B is 1,2-phenylene-[(2,4,7- trimethyl-1-lndenyl)(1-phenyl-2-indenyl)]-zirconium(IV) dichloride.

8. Catalyst system according to any one of claims 1-7, wherein the molar ratio of component A to component B is from 0.1 to 4.0.

9. Catalyst system according to any one of claims 1-8, wherein the component A and the component B are carried on a support, preferably wherein both components are carried on the same support, preferably wherein the support is selected from silica, alumina, magnesia, titania, zirconia, clay, zeolite, graphite, and polymeric particles, preferably silica.

10. Catalyst system according to any one of claims 1-9, wherein the catalyst system comprises a cocatalyst, preferably wherein the cocatalyst is methyl aluminoxane.

11. Catalyst system according to claim 10, wherein the catalyst system comprises > 6.0 and < 40.0 wt% of Al, with regard to the total weight of the catalyst system, preferably > 7.0 and < 35.0 wt%, more preferably > 10.0 and < 30.0 wt%.

12. Catalyst system according to any one of claims 1-11 , wherein the catalyst system comprises > 0.10 and < 1.00 wt% of the sum of Zr, Hf and Ti, with regard tot the total weight of the catalyst system, preferably > 0.15 and < 0.50 wt%, more preferably > 0.15 and < 0.30 wt%.

13. Process for producing a catalyst system according to any one of claims 10-12, wherein the process involves the steps in this order of:

(i) treating the support with the cocatalyst, followed by

(ii) addition of the components A and B; or

(i) treating the components A and B with the cocatalyst, followed by

(ii) addition of the support; or

(iii) combining the activated support with the activated components A and B.

14. Process for polymerisation of a reaction mixture comprising ethylene and/or propylene using the catalyst system according to any one of claims 1-12.

15. Process according to claim 14, wherein the process is an ethylene homo- or copolymerisation process.