Method for determining the compressibility characteristics of olefin polymerization catalysts

Abstract

The present disclosure relates to a method for determining the compressive properties of an olefin polymerization catalyst, comprising subjecting particles of an olefin polymerization catalyst to a microcompression test to obtain crush strength data of the particles of the olefin polymerization catalyst, thereby determining the compressive properties of the olefin polymerization catalyst. The present disclosure further relates to a method for evaluating the quality of an olefin polymerization catalyst, comprising determining the compressive properties of the olefin polymerization catalyst, and evaluating the quality of the olefin polymerization catalyst from information obtained from the determination of the compressive strength of the olefin polymerization catalyst. The present disclosure further relates to a method for predicting the performance of an olefin polymerization catalyst in an olefin polymerization process from its compressive strength descriptors, characterized in that the compressive properties of the olefin polymerization catalyst are determined as disclosed. Moreover, the present disclosure relates to an olefin polymerization catalyst, the olefin polymerization catalyst having a Weibull coefficient greater than 2.

Description

[Technical field]

[0001] The present disclosure relates to characterizing olefin polymerization catalyst particles, and more particularly to determining the compressive properties of olefin polymerization catalysts, including key descriptors for determining the mechanical properties of olefin polymerization catalysts, determining the quality of olefin polymerization catalysts, and predicting the performance of olefin polymerization catalysts in olefin polymerization processes. The present disclosure further relates to polymerization catalysts having specific compressive strength descriptors. [Background technology]

[0002] An important aspect of olefin polymerization catalysts consists of the mechanical properties of the support material used to prepare the catalyst. In particular, the viscoelastic properties of the starting support material will determine the initial fragmentation behavior and internal morphology evolution of the catalyst in the polymerization process, and thus affect the outcome of the polymerization reaction. If the carrier material is too brittle, the breakage rate will be too fast under polymerization conditions, resulting in fines and fluff due to uncontrollable fragmentation of the initial particles. If the carrier material is too strong, it cannot be easily broken under polymerization conditions, leading to low polymerization activity, mainly due to the inability to access active sites and the limited mass transfer inside the reactants. In fact, the initially formulated catalyst / polymer macroparticles exhibit irregular shapes, thus causing great restrictions in mass and heat transfer from the outside, and even great problems in flowability, leading to poor performance of the polymerization reactor. Compression tests are commonly used to measure the mechanical behavior of individual particles from powder samples, including viscoelastic properties or fracture behavior (see, for example, Antonyuk et al., Chemical Engineering Science 60 (2005) 4031-4044). In particular, microcompression tests are widely used in materials science to measure the mechanical strength of micro-sized objects, including microporous spherical particles (see, for example, Paul et al., Advanced Powder Technology 25 (2014) 136-153). More specifically, microcompression techniques have been utilized in the development of olefin polymerization catalysts to evaluate the suitability of a given carrier material to be used as a support for olefin polymerization catalysts, for example using dialkoxymagnesium granules (US Pat. No. US8632882B2), layered ion-exchanged silicates (JP2019172958, EP0874006B1, US6353063 or EP1241188B1) or silica (JP2017071741A).However, the aforementioned studies are limited to determining the mechanical strength of the initial support material as an average value of a series of measurements on a sample population, which does not necessarily reflect the actual mechanical strength of the final catalyst and gives little indication of its ultimate performance and operability in the polymerization process.

[0003] Meanwhile, it is well known in scientific and patent literature that the dispersion of structural defects and polymerization active sites within catalyst particles and within a population of catalyst particles affects the final performance of catalysts in polymerization reactors during olefin polymerization process reactions. More specifically, if the polymerization sites, i.e., catalytic active sites, are evenly distributed within a catalyst particle, the stress developed by the nascent polymer will be evenly distributed within the particle, resulting in homogeneous fragmentation of the catalyst. As a result, the individual particle growth of catalyst / polymer particles will be uniform, thus resulting in the development of a narrow particle size distribution in the process (there is no small-sized particle and no large-sized particle).

[0004] For example, US Pat. No. 7,754,834 B2 teaches that polymer particles are formed by continuously exposing olefin monomers to a catalyst present in a polymerization reactor, where the polymer particles grow from the initial formation of "micro-particle clusters" at the active sites of the catalyst particles. As these fine particle clusters grow, voids are created between the growing primary polymer particles, which ultimately account for 10-25% of the polymer particle volume. The presence of such voids in the final polymer particles results in a reduction in the bulk density of the polymer powder. A reduction in bulk density of the polymer powder typically leads to reduced production throughput in the polymerization plant, operability problems such as fines formation, reduced material flowability, excessive carryover, and is generally associated with mass and heat transfer limitations that result in sheeting and chunking in the polymerization reactor.

[0005] In an attempt to reduce sheeting and / or chunking in a polymerization reactor during operation, International Publication No. WO 28212852 A1 describes pore sizes in the range of 300-1500 Å and / or 700 mm diameter polymeric polymeric sintering reactors. 2 It is disclosed that olefin polymerization catalyst compositions prepared from supports having 10-80 volume % of pores with a BET specific surface area of ​​less than 100 nm / g exhibit catalyst components uniformly dispersed throughout the support material. However, the dispersion of catalyst components within the support material is only assessed as the difference in aluminum content between the surface and interior of the catalyst by XPS, which is a qualitative method for assessing the actual dispersion of catalytically active components within the particle. No actual measurements of aluminum dispersion throughout the support are reported to support this disclosure.

[0006] Similarly, WO2016176135A1 teaches that poor operability of polymerization reactors is often due to non-uniform distribution of catalytic active sites within the support pore network. The inventors claim that the use of supported catalyst compositions with macropore volumes up to 1.23 mL / g shows good catalyst flowability and provides enhanced reactor operability. However, no polymerization data is disclosed that allows confirmation of improved catalyst performance and actual operability in polymerization.

[0007] In a comparable attempt to reduce sheeting and / or chunking in polymerization reactors during operation, WO2018175071A1 discloses that olefin catalyst compositions prepared from supports having macroporosities in the range of 0.15-0.50 mL / g result in increased deposition of catalyst components on and / or in the support material. The inventors claim that the use of such supports reduces sheeting and / or chunking in polymerization reactors during polymerization. However, no improvement in catalyst activity or bulk density of the resulting polymer powder is shown to be provided.

[0008] US Patent US7244785B2 discloses that when solid polymer compounds, such as aluminoxane, are used as activators, the loading of the activator during catalyst preparation directly affects the catalyst productivity and the bulk density of the resulting polymer powder: the higher the loading of aluminoxane activator in the catalyst preparation, the higher the productivity and bulk density. However, according to the inventors' report, when the loading of aluminoxane exceeds 6.40 mol MAO / g silica, fouling will begin to occur on the polymerization reactor wall due to the elution of active species into the reaction medium. This fouling phenomenon at higher loading of aluminoxane prevents the inventors from fully utilizing the potential of the catalyst system to achieve maximum catalyst productivity with high bulk density of polymer powder.

[0009] Research into the influence of particle mechanical strength on the performance of catalysts in olefin polymerization has so far been limited to the measurement of the mechanical strength of support materials under ambient conditions.However, it is well known in the art that the mechanical strength of porous particles consisting of a network of holes and voids inside spherical particles of a given material, such as silica or alumina, is highly dependent on the presence of structural defects (characterized by pore size distribution, pore connectivity and also by pore tortuosity) (see Kanellopoulos et al., 2007 "Evaluation of the Internal Particle Morphology in Catalytic Gas-Phase Olefin Polymerisation Reactors", Ind. Eng. Chem. Res. 2007, 46, 1928-1937), the nature and size of the structural defects and their distribution inside the spherical particles.

[0010] In conclusion, structural defects and their distribution inside the particle can be described in terms of pore structure (open, closed, channels or cavities), pore size (micropores, mesopores and macropores) and pore size distribution. In the specific case of single-site catalysts prepared from organometallic transition metal complexes, oligomeric aluminoxane activators and inorganic oxide microspherical porous supports, the pore structure of the final catalyst particle is dictated by the pore structure of the starting support material, the nature and amount of chemicals loaded on the support surface and the operating conditions used during catalyst preparation.

[0011] For example, WO2016176135A1 shows that when methylaluminoxane is used as an activator, the porosity of the final catalyst is different from that of the starting support material and varies depending on the conditions applied during catalyst preparation. Therefore, it is reasonable to assume that the structural defects and their distribution inside the single-site catalyst particles prepared from organometallic transition metal complexes, oligomeric aluminoxane activators and inorganic oxide microspherical porous supports will be determined by the nature and amount of chemicals loaded on the surface of the support and the operating conditions used during catalyst preparation. Summary of the Invention [Problem to be solved by the invention]

[0012] The objective of the present disclosure is to be able to characterize micro-sized particulate olefin polymerization catalysts and to predict their performance as olefin polymerization catalysts under olefin polymerization conditions derived by the method of the present invention, so as to overcome the above mentioned limitations.

[0013] The object of the present disclosure is achieved by a method for determining the compressibility characteristics of an olefin polymerization catalyst, a method for evaluating the quality of an olefin polymerization catalyst, a method for predicting the performance of an olefin polymerization catalyst, and an olefin polymerization catalyst, which methods are characterized by the features stated in the independent claims. Preferred embodiments of the present disclosure are disclosed in the dependent claims. [Means for solving the problem]

[0014] The present disclosure is based on the idea of ​​determining the compressive properties of olefin polymerization catalyst particles by microcompression testing. It has also been found that a Weibull distribution analysis of the obtained compressive strength data allows the interparticle distribution of structural defects within the catalyst particles to be estimated, which in turn is an efficient method for assessing the uniformity of the distribution of catalyst components within a population of particles. It has also been found that the information obtained from the microcompression test can be correlated with polymerisation performance indicators, such as the variation in the polymerization activity for a given catalyst.

[0015] In the following, the present disclosure will be described in more detail by way of preferred embodiments with reference to the accompanying drawings. [Brief description of the drawings]

[0016] [Figure 1] FIG. 1 shows a Weibull distribution analysis for a group of olefin polymerization catalysts. [Diagram 2] FIG. 2 shows the relationship between the Weibull scale and MAO loading for a group of olefin polymerization catalysts. [Diagram 3] FIG. 3 shows the relationship between Weibull modulus and MAO loading for a group of olefin polymerization catalysts. [Figure 4] FIG. 4 shows the relationship between catalytic activity and MAO loading for a group of olefin polymerization catalysts. [Diagram 5] FIG. 5 shows the standard deviation of the catalytic activity versus MAO loading. [Figure 6] FIG. 6 shows the Weibull coefficient versus catalyst activity for a group of olefin polymerization catalysts. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] The present disclosure relates to determining the compressive properties of olefin polymerization catalysts and utilizing the information obtained in assessing the quality of said olefin polymerization catalysts and predicting their performance in said olefin polymerization processes.

[0018] As used herein, the term "compressive character" refers to the expression of the mechanical strength of a material in one or more parameters, i.e. compressive strength descriptors, which relate to its resistance to compressive stresses applied to it and are obtained by measuring this property.

[0019] As used herein, the term "crushing strength" refers to the maximum compressive stress that a brittle solid can withstand without breaking. As used within the context of the present disclosure, it particularly refers to the ability of individual particles of the olefin polymerization catalyst of the present invention to withstand the stresses applied to them in a microcompression test under an inert atmosphere as discussed herein.

[0020] As used herein and hereinafter, the term "compressive strength" refers to the characteristic of mechanical strength as a property of a material. As used within the context of this application, it refers to the average measured crushing strength of a number of particles of the olefin polymerization catalyst of the present invention as discussed herein.

[0021] The present disclosure relates to a method for determining a compressive property of an olefin polymerization catalyst, comprising subjecting particles of an olefin polymerization catalyst to a microcompression test to obtain crush strength data for said particles of said olefin polymerization catalyst and to determine said compressive property of said olefin polymerization catalyst.

[0022] The method of the present invention for determining the compressive properties, such as those mentioned above including compressive strength and Weibull parameters of olefin polymerization catalysts as described herein and hereinafter, is a very efficient characterization method for assessing the quality of an olefin polymerization catalyst and for predicting its performance in an olefin polymerization process.

[0023] Crushing strength ( Crushing strength )

[0024] The method of the present disclosure relies on determining the crush strength of particles of an analyzed olefin polymerization catalyst.

[0025] The crush strength may be determined by measuring the individual crush strength of any 10 or more particles, for example exactly 10 particles, to obtain crush strength data.

[0026] The determination of the crush strength of the olefin polymerization catalyst particles can be efficiently carried out by a compression test, such as a microcompression test, under an inert atmosphere.

[0027] In an exemplary embodiment, the individual crushing strength of any 10 or more particles is measured using a Shimadzu Corporation Micro Compression Tester MCT-510.

[0028] Compressive strength

[0029] The crush strength data obtained from the individual olefin polymerization catalyst particles can then be used to calculate an average value of the measurements to provide the compressive strength of the analyzed olefin polymerization catalyst, the average value of the measurements being calculated, preferably after removing statistical outliers.

[0030] Weibull distribution analysis

[0031] Preferably, in the method of the present invention, the compressive property is determined by deriving a Weibull distribution analysis of the crush strength data of the analyzed polymerization catalyst particles. The Weibull analysis of the compressive strength data can be performed using standard statistical analysis software, such as Minitab, Excel or Origin.

[0032] The Weibull distribution is commonly used in materials science to describe the variability in the fracture mechanical strength of brittle materials within a sample population. Two characteristic parameters of the Weibull analysis in compression tests are the Weibull modulus and the compressive strength. The Weibull modulus is a dimensionless parameter that describes the variability in the distribution of measured compressive strengths within a single grain of a sample population. The Weibull modulus corresponds to the shape parameter of the Weibull distribution.

[0033] In compression tests, the scale parameter of the Weibull distribution describes the compressive strength of a representative single particle of the sample population and is expressed in units of MPa.

[0034] A low Weibull modulus corresponds to a large variability in the measured mechanical strength within the sample population and indicates a non-uniform distribution of structural defects in the material, resulting in non-uniform fracture behavior under stress. A high Weibull modulus, on the other hand, indicates a uniform distribution of defects in the material, resulting in uniform fracture behavior under stress. A high scale parameter corresponds to samples with high grain strength. A low scale parameter corresponds to samples with low grain strength.

[0035] The use of both parameters of the Weibull distribution is preferred in the method of the present invention to describe the final properties of the studied material, where, in the case of olefin polymerization catalyst particles, both parameters will influence the polymerization behavior and the properties of the final polymer powder.

[0036] Thus, in one embodiment of the method of the present invention, the method comprises deriving a scale parameter and a Weibull modulus of a Weibull distribution of an olefin polymerization catalyst from crush strength data to determine the compressive properties of the olefin polymerization catalyst.

[0037] Evaluation of the quality of olefin polymerization catalysts.

[0038] The present disclosure provides a method for evaluating the quality of an olefin polymerization catalyst, comprising: (o) determining the compressive properties of the olefin polymerization catalysts discussed herein; and (p) assessing the quality of the olefin polymerization catalyst from information obtained from determining the compressive properties of the olefin polymerization catalyst. The method includes the steps of:

[0039] As used in the specification and hereinafter, the term "quality" refers to one or more characteristics and / or properties possessed by the olefin polymerization catalyst of the present invention, particularly in relation to its ability to perform acceptable in an olefin polymerization process. In particular, the desired quality includes the susceptibility of the olefin polymerization catalyst to smooth fragmentation as defined by its mechanical properties. The results of the method for assessing the quality can be used to determine the selection of olefin polymerization and / or process operating conditions of an olefin polymerization process, particularly during a prepolymerization step, preferably to ensure a controllable fragmentation step within said process.

[0040] Typically, a method for assessing the quality of an olefin polymerization catalyst is accomplished by measuring the individual crush strengths of at least 10 randomly selected individual particles within a sample population of olefin polymerization catalyst using a microcompression tester, and performing a Weibull distribution analysis of the resulting crush strength data, preferably after removing statistical outliers, to derive a Weibull modulus and Weibull scale parameter for the olefin polymerization catalyst.

[0041] In certain embodiments, a method for assessing the quality of a supported polymerization catalyst includes comparing one or more parameters of a Weibull distribution analysis to a predetermined target value. In particular embodiments, the method includes comparing the Weibull coefficients and / or Weibull scale parameters to respective predetermined target values ​​to assess the quality of the olefin polymerization catalyst.

[0042] Thus, in one embodiment, a method for assessing the quality of an olefin polymerization catalyst comprises: (p1) measuring the individual crush strengths of at least 10 randomly selected individual particles within a sample population of the olefin polymerization catalyst using a microcompression tester and performing a Weibull distribution analysis of the resulting crush strength data to derive a Weibull modulus and a Weibull scale parameter for the olefin polymerization catalyst; and (p2) comparing the Weibull coefficients and / or the Weibull scale parameters with predetermined individual target values ​​to evaluate the quality of the olefin polymerization catalyst. Includes.

[0043] The interparticle distribution of structural defects within a catalyst particle can be estimated by the Weibull modulus of the Weibull distribution of the obtained crush strength data. This is an efficient way to evaluate the uniformity of the catalyst component distribution within a population of particles. Moreover, the information obtained from the microcompression test can be correlated with polymerization performance indicators, such as the variation in the polymerization activity of a given catalyst.

[0044] Therefore, the method for assessing the quality of an olefin polymerization catalyst preferably comprises (q) estimating the interparticle distribution of structural defects in particles of the olefin polymerization catalyst from a Weibull distribution analysis.

[0045] Moreover, the method of the present invention for assessing the quality of an olefin polymerization catalyst preferably comprises (r) establishing a relationship between one or more compressive strength descriptors of said analyzed polymerization catalyst, such as compressive strength or one or more parameters of said Weibull analysis, in particular the Weibull modulus, and one or more polymerization performance indicators, such as the polymerization activity and / or the variation in polymerization activity with respect to the number of repeated polymerization runs, preferably the variation in polymerization activity.

[0046] As used herein, the term "relationship" refers to a situational and / or causal, preferably causal, association and / or correlation between a referenced property and / or polymerization performance index of an olefin polymerization catalyst.

[0047] Still further, the method for assessing the quality of an olefin polymerization catalyst comprises (s) establishing a relationship between one or more compressive strength descriptors of said analyzed polymerization catalyst, such as compressive strength or one or more parameters of said Weibull analysis, in particular the Weibull modulus, and one or more properties of a polymer powder obtained by polymerizing an olefin monomer with said analyzed polymerization catalyst.

[0048] Predicting performance of olefin polymerization catalysts.

[0049] The present specification further provides a method for predicting the performance of an olefin polymerization catalyst in an olefin polymerization process, wherein the compressive strength of the olefin polymerization catalyst is determined as discussed herein.

[0050] Typically, the methods for predicting the performance of an olefin polymerization catalyst in a polymerization reaction discussed herein include: (x) determining the compressive properties of the olefin polymerization catalyst; and (y) predicting the performance of said olefin polymerization catalyst by evaluating information obtained from the determination of the compressive properties of said olefin polymerization catalyst. Includes.

[0051] Moreover, the method for predicting the performance of an olefin polymerization catalyst in a polymerization reaction can be used to predict the properties of polymer powders obtained by polymerizing olefin monomers using the olefin polymerization catalyst.

[0052] The method in particular makes it possible to predict the bulk density and / or particle size distribution of polymer powders obtained, for example, by polymerizing an olefin monomer in the presence of an olefin monomer, optionally an olefin comonomer, in the presence of a particulate olefin polymerization catalyst in a polymerization reactor, optionally in a series of multiple polymerization reactors. The bulk density can also be used to predict the fluidized bulk density, which is an important operational parameter determining the reactor throughput and operability.

[0053] In one embodiment, a method for predicting the performance of an olefin polymerization catalyst comprises: (y1) establishing a relationship between said catalyst compressive strength descriptor, such as compressive strength or Weibull parameter, and one or more physical and / or mechanical properties of said polymerization catalyst; and predicting the performance of said olefin polymerization catalyst by evaluating information obtained from said relationship.

[0054] One or more of the physical and / or mechanical properties of the polymerization catalyst may be selected from the group consisting of particle size, particle size distribution, density, and microstructure, e.g., the microstructure described above including crystalline and amorphous fractions, specific surface area, porosity, pore volume, pore size, pore size distribution, pore shape, tortuosity of the pore network, and pore connectivity.

[0055] In a further embodiment, the method for predicting the performance of an olefin polymerization catalyst comprises (y2) assessing the quality of an olefin polymerization catalyst as discussed herein, and predicting the performance of the olefin polymerization catalyst based on information obtained from assessing the quality of the olefin polymerization catalyst.

[0056] The method for predicting the performance of an olefin polymerization catalyst preferably further comprises: (y3) performing a Weibull distribution analysis of said crush strength data; and comparing one or more parameters of said Weibull distribution, or any combination thereof, to a predetermined target value to predict the performance of said olefin polymerization catalyst.

[0057] In a particular example, a method for predicting the performance of an olefin polymerization catalyst preferably includes determining a Weibull coefficient x scale parameter product and a Weibull coefficient / scale parameter ratio; and comparing the Weibull coefficient x scale parameter product and the Weibull coefficient / scale parameter ratio to respective predetermined target values ​​to predict the performance of the olefin polymerization catalyst during a polymerization reaction.

[0058] Olefin Polymerization Catalysts

[0059] The olefin polymerization catalysts of the present disclosure are generally single-site catalysts. Single-site catalysts typically comprise (i) a transition metal complex, (ii) a cocatalyst, and, optionally, (iii) a support.

[0060] It has surprisingly been determined by the method of the present invention that olefin polymerization catalysts having a Weibull coefficient of greater than 2, preferably greater than 2.5, more preferably greater than 3, typically from 2 to 10, preferably from 2.5 to 8.5, and even more preferably from 3 to 8, provide superior performance in olefin polymerization processes.

[0061] The olefin polymerization catalyst further preferably has a Weibull scale parameter of greater than 6 MPa, preferably greater than 7 MPa, more preferably 8 MPaav, typically from 6 to 20 MPa, preferably from 7 to 18 MPa, more preferably from 8 to 15 MPa.

[0062] It is further preferred that the compressive strength of the olefin polymerization catalyst particles is at least 5 MPa, preferably at least 7 MPa, more preferably from 7 to 15 MPa, as measured in a microcompression tester as discussed herein.

[0063] Transition metal complexes (i)

[0064] The transition metal complex comprises a transition metal (M) from groups 3 to 10 of the periodic table (IUPAC 2007), or an actinide or lanthanide transition metal (M).

[0065] In accordance with the present invention, the term "transition metal complex" includes any metallocene or non-metallocene compound of a transition metal, which has at least one organic (coordination) ligand and has catalytic activity alone or together with a cocatalyst. Such transition metal compounds are well known in the art, and the present invention covers compounds of metals from groups 3 to 10, such as groups 3 to 7, or groups 3 to 6, such as groups 4 to 6, as well as the lanthanides or actinides of the periodic table (IUPAC 2007).

[0066] In one embodiment, the transition metal complex (i) has the formula (iI): (L) m R n MX q (ii) Where: "M" is a transition metal (M) in groups 3 to 10 of the periodic table (IUPAC 2007), Each "X" is independently a monoanionic ligand, e.g., a σ-ligand; each "L" is independently an organic ligand that coordinates to a transition metal "M"; "R" is a bridging group that links multiple organic ligands (L); "m" is 1, 2 or 3, preferably 2; "n" is 1 or 2, preferably 0 or 1; "q" is 1, 2 or 3, preferably 2, and m+q is equal to the valence of the transition metal (M).

[0067] "M" is preferably selected from the group consisting of zirconium (Zr), hafnium (Hf), or titanium (Ti), more preferably selected from the group consisting of zirconium (Zr) and hafnium (Hf). "X" is preferably a halogen, most preferably Cl.

[0068] Most preferably, the transition metal complex (i) is a metallocene complex, which comprises a transition metal compound as defined above, which comprises a cyclopentadienyl, indenyl or fluorenyl ligand as the substituent "L", which further comprises one or more substituents such as alkyl, aryl, arylalkyl, alkylaryl, silyl, siloxy, alkoxy or other heteroatom groups. Suitable metallocene catalysts are known in the art and are disclosed, inter alia, in WO-A-95 / 12622, WO-A-96 / 32423, WO-A-97 / 28170, WO-A-98 / 32776, WO-A-99 / 61489, WO-A-03 / 010208, WO-A-03 / 051934, WO-A-03 / 051514, WO-A-2004 / 085499, EP-A-1752462 and EP-A-1739103.

[0069] In another embodiment, the transition metal complex (i) has the following formula (i-II): [ka] where each X is independently a halogen atom, C 1~6 Alkyl group, C 1~6 an alkoxy group, a phenyl group, or a benzyl group; each Het is independently a monocyclic heteroaromatic ring containing at least one heteroatom selected from an O atom or a S atom; L is -R'2Si-, where each R' is independently optionally substituted with an alkoxy group having 1 to 10 carbon atoms; 1~20 Hydrocarbyl or C 1~10 is alkyl; M is Ti, Zr or Hf; Each R1 may be the same or different; C 1~6 Alkyl group or C 1~6 is an alkoxy group; each n is 1 to 2; Each R2 may be the same or different; C 1~6 Alkyl group, C 1~6 an alkoxy group or a -Si(R)3 group; Each R is C 1~10 Alkyl group or 1 to 3 C 1~6 a phenyl group optionally substituted by an alkyl group; and Each p is an integer from 0 to 1.

[0070] Preferably, the compound of formula (i-II) has the following structure (i-III): [ka] where each X is independently a halogen atom, C 1~6 Alkyl group, C 1~6 an alkoxy group, a phenyl group, or a benzyl group; L is MeSi-; Each R1 may be the same or different; C 1~6 an alkyl group, such as methyl or t-Bu; each n is 1 to 2; R2 is a -Si(R)3 alkyl group; Each p is 1; Each R is C 1~6 It is an alkyl group or a phenyl group.

[0071] Cocatalyst (ii)

[0072] To form the polymerization catalyst, a cocatalyst, also known as an activator, is used, as is well known in the art. Cocatalysts containing Al or B are well known and can be used herein. The use of aluminoxanes (e.g., MAO) or boron-based cocatalysts (e.g., borates) is preferred.

[0073] According to the present invention, a cocatalyst containing a Group 13 element is required, such as a boron-containing cocatalyst or an Al-containing cocatalyst. Most preferably, an aluminoxane cocatalyst is used in combination with the metallocene catalyst complex defined above.

[0074] The alumoxane cocatalyst can be of formula (ii-I): [ka] Here, n is 6 to 20, and R has the following meaning:

[0075] Aluminoxanes are formed, for example, by partial hydrolysis of organoaluminum compounds, such as those of the formulae AlR3, AlR2Y and Al2R3Y3, where R is, for example, C1-C 10 Alkyl, preferably C1 to C5 alkyl, or C3 to C 10 Cycloalkyl, C7-C 12 arylalkyl or alkylaryl, and / or phenyl or naphthyl, where Y is a hydrogen atom, a halogen atom, preferably a chlorine atom or a bromine atom, or a C1-C 10 The alkoxy group is preferably methoxy or ethoxy. The resulting oxygen-containing aluminoxanes are generally not pure compounds but are combinations of oligomers of the formula (ii-I).

[0076] A preferred aluminoxane is methylaluminoxane (MAO). The aluminoxanes used according to the invention as cocatalysts are not pure compounds due to their mode of preparation, therefore hereinafter the molar ratios of the aluminoxane solutions are based on their aluminum content.

[0077] A boron-containing cocatalyst may also be used, optionally in combination with an aluminoxane cocatalyst.

[0078] Boron-containing cocatalysts of interest include those of formula (ii-II) below: BY3(ii-II) wherein Y may be the same or different and is a hydrogen atom, an alkyl group of 1 to about 20 carbon atoms, an aryl group of 6 to about 15 carbon atoms, an alkylaryl, an arylalkyl, a haloalkyl or a haloaryl, each of which has 1 to 10 carbon atoms in the alkyl radical and 6 to 20 carbon atoms in the aryl radical, or a fluorine atom, a chlorine atom, a bromine atom or an iodine atom. Preferred examples of Y are a fluorine atom, trifluoromethyl, an aromatic fluorinated group such as p-fluorophenyl, 3,5-difluorophenyl, pentafluorophenyl, 3,4,5-trifluorophenyl and 3,5-di(trifluoromethyl)phenyl. Preferred choices are trifluoroborane, tris(4-fluorophenyl)borane, tris(3,5-difluorophenyl)borane, tris(4-fluoromethylphenyl)borane, tris(2,4,6-trifluorophenyl)borane, tris(pentafluorophenyl)borane, tris(3,5-difluorophenyl)borane and / or tris(3,4,5-trifluorophenyl)borane.

[0079] Particularly preferred is tris(pentafluorophenyl)borane.

[0080] However, it is preferred to use borates, ie compounds which contain borate.

[0081] These compounds generally comprise anions of the following formulas (ii-III): (Z)4B - (ii-III) wherein Z is an optionally substituted phenyl derivative, wherein the substituent is halo-C 1~6 It is an alkyl or halo group. The preferred choices are fluoro or trifluoromethyl. Most preferably, the phenyl group is perfluorinated.

[0082] Such ionic cocatalysts are preferably weakly-coordinating anions, such as tetrakis(pentafluorophenyl)borate or tetrakis(3,5-di(trifluoromethyl)phenyl)borate.

[0083] Suitable cationic counterions include triphenylcarbenium and protonated amine or aniline derivatives, such as methylammonium, anilinium, dimethylammonium, diethylammonium, N-methylanilinium, diphenylammonium, N,N-dimethylanilinium, trimethylammonium, triethylammonium, tri-n-butylammonium, methyldiphenylammonium, pyridinium, p-bromo-N,N-dimethylanilinium, or p-nitro-N,N-dimethylanilinium.

[0084] Preferred ionizing compounds that may be used in accordance with the present invention include: tributylammonium tetrakis(pentafluorophenyl)borate, tributylammonium tetrakis(trifluoromethylphenyl)borate, tributylammonium tetrakis(4-fluorophenyl)borate, N,N-dimethylcyclohexylammonium tetrakis(pentafluorophenyl)borate, N,N-dimethylbenzylammonium tetrakis(pentafluorophenyl)borate, N,N-dimethylanilinium tetrakis(pentafluorophenyl)borate, N,N-di(propyl)ammonium tetrakis(pentafluorophenyl)borate, di(cyclohexyl)ammonium tetrakis(pentafluorophenyl)borate, triphenylcarbenium tetrakis(pentafluorophenyl)borate, or Ferrocenium tetrakis(pentafluorophenyl)borate.

[0085] Preferably, the following is provided: triphenylcarbenium tetrakis(pentafluorophenyl)borate, N,N-dimethylanilinium tetrakis(pentafluorophenyl)borate, N,N-dimethylcyclohexylammonium tetrakis(pentafluorophenyl)borate, or N,N-Dimethylbenzylammonium tetrakis(pentafluorophenyl)borate.

[0086] The preferred borates for use in the present invention include the trityl, i.e., triphenylcarbenium ion. Hence, the use of Ph3CB(PhF5)4 and their analogs is particularly preferred.

[0087] Suitable amounts of promoter will be known to those skilled in the art.

[0088] Preferably, the amount of promoter is selected to be less than a defined molar ratio.

[0089] In the case of boron-containing catalysts, the molar ratio of the feed amount of boron (B) to the metal ion (M) (preferably zirconium) of the metallocene boron / M can be in the range of 0.1:1 to 10:1 mol / mol, preferably 0.3:1 to 7:1 mol / mol, in particular 0.3:1 to 5:1 mol / mol.

[0090] More preferably, the molar ratio of the supply amount of boron (B) to the metal ion (M) (preferably zirconium) of the metallocene boron / M is 0.3:1 to 3:1.

[0091] The molar ratio of Al from the aluminoxane to the metal ion (M) (preferably zirconium) of the metallocene Al / M may be in the range of 1:1 to 2000:1 mol / mol, preferably 10:1 to 1000:1 mol / mol, more preferably 50:1 to 600:1 mol / mol.

[0092] Support (iii)

[0093] The polymerization catalyst of the present invention may be in the form of a solid but unsupported form prepared according to the protocol of WO03 / 051934.The polymerization catalyst of the present invention is preferably in a solid supported form.The particle support material used may be an inorganic porous support, such as clay, such as layered ion-exchanged silicate, or an inorganic oxide, such as silica, alumina, silica-alumina or titanium oxide.Preferably, the particle support material is selected from the group consisting of silica, alumina, or mixed oxides, such as silica-alumina, in particular silica.

[0094] The use of a silica support is preferred.

[0095] Particularly preferably, the support is a porous material so that the complex can be supported within the pores of the particulate support using similar processes as described, for example, in WO 94 / 14856, WO 95 / 12622, WO 2006 / 097497 and EP 1828266.

[0096] The average particle size of the support, e.g., silica support, can typically be from 10 to 100 μm. The average particle size (i.e., median particle size, D 50) can be determined using a laser diffraction particle size analyzer Malvern Mastersizer 3000 (sample dispersion: dry powder).

[0097] The average pore size of the support, for example a silica support, can range from 10 to 100 nm and the pore volume can be from 1 to 3 mL / g.

[0098] Examples of suitable support materials are, for example, ES757 manufactured and sold by PQ Corporation, Sylopol 948 manufactured and sold by Grace, or SUNSPERA DM-L-303 silica manufactured and sold by AGC Si-Tech Co. The support can optionally be calcined prior to use in the catalyst preparation to reach an optimum silanol group content.

[0099] Typically, the catalyst may comprise 5 to 500 μmol, such as 10 to 100 μmol, of transition metal per gram of support, e.g., silica, and 3 to 15 mmol of Al per gram of support, e.g., silica.

[0100] Working Example

[0101] Surface area 295m 2 A series of metallocene catalysts based on silica support with 1.0 μm / g, pore volume of 1.6 mL / g, average pore diameter of 216 Å and median particle size of 25 μm were prepared, in which the loadings of rac-dimethylsilanediylbis{2-(5-(trimethylsilyl)furan-2-yl)-4,5-dimethylcyclopentadiene-1-yl}zirconium dichloride metallocene and methylaluminoxane activator were varied, and the loading of methylaluminoxane in the synthesis reactor was varied during catalyst preparation. The obtained catalysts were analyzed for their elemental composition by ICP-OES, and their mechanical strength was measured as the compressive strength of the catalyst particles using a microcompression test.

[0102] Chemicals and Raw Materials

[0103] Methylaluminoxane (30 wt % MAO solution in toluene, Axion CA 1330) was purchased from Lanxess.

[0104] The rac-dimethylsilanediylbis{2-(5-(trimethylsilyl)furan-2-yl)-4,5-dimethylcyclopentadiene-1-yl}zirconium dichloride metallocene was synthesized according to known procedures disclosed in US Pat. No. 6,326,493 B1.

[0105] Comparative Example 1

[0106] The pretreated silica was a commercially available synthetic amorphous silica, ES757, obtained from PQ Corp. The pretreatment refers to the commercial calcination of the silica at 600° C. according to conventional PO catalyst technology.

[0107] Preparation of Catalysts (Examples 1 to 5 in Tables 1A and 1B and Table 2)

[0108] The pretreated support is a synthetic amorphous silica obtained commercially from PQ Corp. The pretreatment refers to commercial calcination of the silica at 600° C. according to conventional techniques.

[0109] All manipulations are carried out under an inert atmosphere of nitrogen using standard Schlenk and glovebox techniques.

[0110] Pre-contact mixture, i.e., 70 μmol of rac-dimethylsilanediylbis{2-(5-(trimethylsilyl)furan-2-yl)-4,5-dimethylcyclopentadiene-1-yl}zirconium dichloride metallocene is dissolved in the desired volume of methylaluminoxane (14 mmol of Al as 30 wt% MAO solution in toluene) set to match the target loading of methylaluminoxane as depicted in Table 1, and an additional volume of toluene is added to reach a total volume of 2.45 mL. The mixture is stirred in a glass vial for 1 hour. The resulting solution is then added dropwise to 1.0 g of pretreated silica support in a glass reactor under gentle mechanical stirring at room temperature within 5 minutes. The crude catalyst is then gently mixed further for 1 hour and left for another 17 hours. The catalyst is then vacuum dried at 60° C. for 30 minutes.

[0111] [Table 1A]

[0112] [Table 1B]

[0113] Catalyst Analysis and Characterization

[0114] Al and Zr contents in solid catalyst components by ICP-OES

[0115] In a glove box, an aliquot of catalyst (approximately 40 mg) is weighed into a glass weighing boat using an analytical balance. The sample is then placed in a second steel container equipped with an air inlet and exposed to air overnight. 5 mL of concentrated nitric acid (65%) is then placed in an Xpress microwave container (20 mL) and used to rinse the contents of the boat. The sample is then subjected to microwave-assisted acid digestion using a MARS 6 laboratory microwave unit, which is heated to 150°C within 20 minutes and held at 150°C for 35 minutes. The digested sample is cooled to room temperature and then transferred into a plastic 100 mL volumetric flask. A standard solution containing 1000 mg / L yttrium (0.4 mL) is added. The flask is then filled with distilled water and shaken. The solution is filtered through a 0.45 μm nylon syringe filter and subjected to analysis using a Thermo iCAP 6300 ICP-OES and iTEVA software.

[0116] The instrument is calibrated for Al and Zr using a blank (5% HNO3 solution prepared from concentrated nitric acid) and six standards of 0.005 mg / L, 0.01 mg / L, 0.1 mg / L, 1 mg / L, 10 mg / L and 100 mg / L of Al and Zr in solution. The solutions contain 5% HNO3 (concentrated nitric acid), 4 mg / L Y standard in distilled water. Plastic volumetric flasks are used. Curve fitting and 1 / concentration weighting are used for the calibration curve. Just before the analysis, the calibration curve is verified and adjusted (re-slope function of the instrument) using the blank, 4 mg / L Y in distilled water and 10 mg / L Al and Zr standard samples with 5% concentrated nitric acid HNO3. To verify the gradient, a quality control sample (QC: 1 mg / L Al; 2 mg / L Zr and 4 mg / L LY, 5% HNO3 solution of concentrated nitric acid in distilled water) is run. The QC sample is also run at the end of the scheduled analytical set.

[0117] The Zr content is monitored using a 339.198 nm wavelength line. The Al content is monitored via a 394.401 nm wavelength line. Y 371.030 nm is used as an internal standard. The reported values ​​are calculated back to the original catalyst sample using the original mass of the catalyst aliquot and the dilution amount.

[0118] Crushing strength The crushing strength of the materials in the examples was determined using a Shimadzu Micro Compression Tester MCT-510. The sample material was dispersed on the lower compression plate, and the particles separated therefrom were selected for measurement using an optical microscope. The diameter of the particles was measured using a microscope software tool. The selected sample particles were compressed with constantly increasing loads until the particles broke or a set maximum force was reached. The crushing strength of the material was determined by the maximum compressive load and particle diameter at which the particles broke. The measurements were performed under inert conditions, with a loading rate of 0.4462 mN / s and a maximum load of 40 mN. The crushing strength of 10 randomly selected particles was measured, and the average value was reported as the compressive strength after removing statistical outliers.

[0119] Weibull distribution analysis was performed from the individual particle data by using commercially available statistical analysis software, such as MiniTab or Origin.

[0120] Parallel Pressure Reactor (PPR) Polymerization Experiment The PPR reactor was preconditioned by flushing it with 80 psi ethylene 10 times, after which the reactor was left unpressurized.

[0121] 5 μmol of TIBA was added as a scavenger along with the correct amount of comonomer to reach a C6 / C2 ratio of 50 mol / kmol during the polymerization process. Heptane was added to the reactor to reach a total volume of 4.1 ml. The solvent addition was carried out at the ambient temperature of the glove box, about 26° C. The reactor was then pressurized to 40 psi with ethylene to check for leaks. After the leak was corrected, the reactor stirring was started and the reactor pressure was controlled at 40 psi for 3 minutes to stabilize the ethylene concentration in the liquid phase.

[0122] The reactor temperature was increased to the polymerization temperature of 85°C, and the temperature and pressure were stabilized and reached steady state. After this, the pressure control was turned on and the reactor was pressurized to the final polymerization pressure. After the reactor conditions were stabilized and reached steady state once again, the catalyst was injected into the reactor together with heptane until the total liquid volume reached 5 ml.

[0123] The reactor pressure was controlled taking into account the operating pressure set point and the monomer uptake rate was monitored for each reactor. The polymerization process was continued for 60 minutes for each reactor, after which the reaction was quenched with CO2.

[0124] Activities are reported as the average of 6-8 polymerizations. Standard deviation (StDev) and coefficient of variation (CoefVar) were determined with standard statistical analysis software, e.g., MiniTab or Origin, as reported in Table 2 below.

[0125] [Table 2]

[0126] The Weibull distributions shown in FIG. 1 indicate that catalyst E1, which has the lowest loading of methylaluminoxane, exhibits a tendency to fracture preferably under low compressive stress, reflected by a low Weibull modulus of 1.36, and exhibits a high number of structural defects and a high heterogeneity in the distribution of structural defects among particles.

[0127] FIG. 2 shows that the addition of catalyst components to the silica porous support (CE1) increases the compressive strength of the catalyst particles, and high loadings of methylaluminoxane result in increased compressive strength (E1-E5). During catalyst preparation, MAO fills the voids present in the porous silica particles, as disclosed in WO198212852A1, WO2016176135A1 or WO201875071A1. In catalyst compositions with a high content of MAO, the density of structural defects is reduced, which results in improved mechanical strength of the catalyst particles.

[0128] On the other hand, Figure 3 confirms the initial observation from the Weibull distribution in Figure 1. The Weibull modulus of the catalyst particles at low loadings of methylaluminoxane is lower than that of the starting support material (E1-E3 for CE1). This suggests that at low loadings, there is not enough methylaluminoxane in the reactor to fill the total amount of voids in the support particles, resulting in a non-uniform interparticle distribution of structural defects in the final catalyst composition compared to the initial interparticle distribution of structural defects of the starting support material.

[0129] Catalyst compositions E1-E5 were further used for the polymerization of ethylene in the presence of 1-hexene as a comonomer in a parallel pressure reactor (PPR). The polymerization activity is reported as the average of 6-8 repetitions of the same polymerization run for each of the catalyst compositions. Figure 4 shows that, contrary to the teaching of US 7244785 B2, methylaluminoxane loading does not necessarily correlate with high polymerization activity.

[0130] On the other hand, Figures 5 and 6 clearly show that the variation in activity over 6-8 polymerization repeats of each catalyst composition E1-E5, as represented by the standard deviation of the polymerization activity, correlates with the methylaluminoxane loading (Figure 5) and thus with the Weibull coefficient of catalyst compressive strength (Figure 6). From this, it can be safely inferred that the higher loading of methylaluminoxane during catalyst preparation promotes a more uniform interparticle distribution of structural defects within the catalyst particle population, providing more reliable polymerization behavior with smaller variations in a series of consecutive polymerization experiments.

[0131] The correlation established between the Weibull parameters of the compressive strength of the catalyst particles and the standard deviations observed from the PPR polymerization experiments illustrates the possibilities offered by the method of characterization of catalyst particles by microcompression tests and the Weibull analysis of the resulting data, with the aim of obtaining a better understanding of the relationship between the catalyst preparation parameters and its performance during the polymerization reaction. Other correlations can be established with descriptors of the polymer powder, such as the bulk density of the particle size distribution or the kinetic parameters of the polymerization reaction.

Claims

1. A method for determining the compression characteristics of an olefin polymerization catalyst, comprising subjecting particles of the olefin polymerization catalyst to a micro-compression test to obtain crushing strength data of the particles of the olefin polymerization catalyst, and determining the compression characteristics of the olefin polymerization catalyst.

2. The method according to claim 1, comprising calculating an average value of measured values to obtain the compression strength of the olefin polymerization catalyst.

3. The method according to claim 1, wherein the Weibull parameter of the olefin polymerization catalyst is obtained by performing a Weibull distribution analysis of the crushing strength data to determine the compression characteristics of the olefin polymerization catalyst.

4. To determine the compression characteristics of the olefin polymerization catalyst, (a) measuring the crushing strength of at least 10 randomly selected individual particles within a sample population of the olefin polymerization catalyst with a micro-compression tester and calculating the average value thereof as the compression strength of the olefin polymerization catalyst; and (b) deriving a scale parameter of the Weibull distribution and a Weibull coefficient of the Weibull distribution from the crushing strength data measured in step (a) Measuring the compression characteristics of an olefin polymerization catalyst The method according to claim 1, comprising

5. The method according to claim 1, wherein the crushing strength is measured by a compression tester.

6. The method according to claim 1, wherein the olefin polymerization catalyst comprises (i) a transition metal complex and (ii) a cocatalyst, or (i) a transition metal complex, (ii) a cocatalyst, and (iii) a support.

7. The method according to claim 6, wherein the support material is selected from the group consisting of layered ion exchange silicates, silica, alumina, silica-alumina, and titanium oxide.

8. A method for evaluating the quality of an olefin polymerization catalyst, comprising (o) Determining the compression characteristics of the olefin polymerization catalyst according to any one of claims 1 to 7, and (p) Evaluating the quality of the olefin polymerization catalyst from the information obtained from the determination of the compression strength of the olefin polymerization catalyst The method comprising the above.

9. (p1) Measuring the individual crushing strengths of at least 10 randomly selected individual particles within a sample population of the olefin polymerization catalyst using a microcompression tester, and deriving a Weibull coefficient and a Weibull scale parameter for the olefin polymerization catalyst by performing a Weibull distribution analysis of the obtained crushing strength data; and (p2) Evaluating the quality of the olefin polymerization catalyst by comparing the Weibull coefficient and / or the Weibull scale parameter with a predetermined individual target value The method for evaluating the quality of an olefin polymerization catalyst according to claim 8, comprising the above.

10. (q) Estimating the interparticle distribution of structural defects within the particles of the olefin catalyst from a Weibull distribution analysis The method for evaluating the quality of an olefin polymerization catalyst according to claim 8, comprising the above.

11. (r) Establishing a relationship between one or more compression strength descriptors of the analyzed polymerization catalyst and one or more polymerization performance indicators; or (s) Establishing a relationship between one or more compression strength descriptors of the analyzed polymerization catalyst and one or more characteristics of a polymer powder obtained by polymerizing an olefin monomer using the analyzed polymerization catalyst The method for evaluating the quality of an olefin polymerization catalyst according to claim 8, comprising the above.

12. The method for evaluating the quality of an olefin polymerization catalyst according to claim 11, wherein the compression strength descriptor is a Weibull coefficient.

13. A method for predicting the performance of an olefin polymerization catalyst in an olefin polymerization process from its compression strength descriptor, wherein the compression characteristics of the olefin polymerization catalyst are determined by the method according to any one of claims 1 to 7.

14. A method for predicting the performance of an olefin polymerization catalyst in a polymerization reaction according to claim 13, comprising: (x) determining the compression characteristics of the olefin polymerization catalyst; and (y) predicting the performance of the olefin polymerization catalyst by evaluating the information obtained from the determination of the compression characteristics of the olefin polymerization catalyst. The method as described above.

15. A method for predicting the performance of an olefin polymerization catalyst in a polymerization reaction according to claim 13, wherein the method is used to predict the characteristics of a polymer powder obtained by polymerizing an olefin monomer using the olefin polymerization catalyst.

16. (y1) establishing a relationship between the catalyst compression strength descriptor and one or more of the physical and / or mechanical characteristics of the polymerization catalyst; and predicting the performance of the olefin polymerization catalyst by evaluating the information obtained from the relationship. The method for predicting the performance of an olefin polymerization catalyst according to claim 13, comprising the above.

17. (y2) evaluating the quality of the olefin polymerization catalyst according to claim 8, and predicting the performance of the olefin polymerization catalyst based on the information obtained from the evaluation of the quality of the olefin polymerization catalyst. The method for predicting the performance of an olefin polymerization catalyst according to claim 13, comprising the above.

18. (y3) performing a Weibull distribution analysis of the crushing strength data; and predicting the performance of the olefin polymerization catalyst by comparing one or more parameters of the Weibull distribution or any combination thereof with a predetermined target value. The method for predicting the performance of an olefin polymerization catalyst according to claim 13, comprising

19. An olefin polymerization catalyst having a Weibull coefficient greater than 2, determined as described in the "Weibull distribution analysis" in the detailed description of the invention.

20. The olefin polymerization catalyst according to claim 19, having a Weibull scale parameter greater than 6 MPa, determined as described in the "Weibull distribution analysis" in the detailed description of the invention.

21. The olefin polymerization catalyst according to claim 19 or 20, having a compression strength of at least 5 MPa when measured with a micro-compression tester.

22. The olefin polymerization catalyst according to claim 19, wherein the olefin polymerization catalyst comprises (i) a transition metal complex, (ii) a cocatalyst, and (iii) a support.

23. The cocatalyst (ii) is an aluminum-containing compound of the following formula (ii-I), that is, formula (ii) is formula (ii-I), 【Chemical Formula 1】 where n is from 6 to 20, and R is C 1 -C 10 alkyl, or C 3 -C 10 cycloalkyl, C 7 -C 12 arylalkyl or alkylaryl, and / or phenyl or naphthyl; and / or, The transition metal complex (i) has the following formula (i-II), 【Chemical Formula 2】 where each X is independently a halogen atom, a C 1～6 alkyl group, a C 1～6 alkoxy group, a phenyl group or a benzyl group; each Het is independently a monocyclic heteroaromatic containing at least one heteroatom selected from an O atom or an S atom; L is -R' 2 Si-, where each R’ is independently an optionally substituted C 1～20 hydrocarbyl or C 1～10 alkyl; M is Ti, Zr or Hf; Each R 1 may be the same or different and is a C 1～6 alkyl group or a C 1～6 alkoxy group; Each n is from 1 to 2; Each R 2 may be the same or different and is a C 1～6 alkyl group, a C 1～6 alkoxy group or a -Si(R) 3 group; Each R is a C 1～10 alkyl group or a phenyl group optionally substituted by 1 to 3 C 1～6 alkyl groups; and each p is from 0 to 1, The olefin polymerization catalyst according to claim 22.

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