Iron complex and preparation method thereof, iron catalyst and application thereof, and polyolefin preparation method

Abstract

The invention relates to the field of polymer preparation, and discloses an iron complex and a preparation method thereof, an iron catalyst and application thereof, and a polyolefin preparation method. The preparation method of the iron complex is simple and stable, the iron catalyst containing the iron complex is stable in catalytic performance and has good 1, 2-structural selectivity when catalyzing polymerization of butadiene monomers, and the obtained polymer is small in particle size and has high crystallinity.

Description

Technical Field

[0001] This invention relates to the field of polymer preparation, specifically to an iron complex and its preparation method, an iron catalyst and its application, and a method for preparing polyolefins. Background Technology

[0002] Meta-1,2-polybutadiene is a thermoplastic resin with unsaturated double bonds in its side chains. The meta-arrangement of these double bonds gives the polymer a high degree of stereoregularity. Due to its unique structure, it is a polymer material that combines the properties of plastics and rubber, and can be used to prepare films, fibers, rubber products, and polymer modifiers.

[0003] Meta-1,2-polybutadiene can be prepared using transition metal coordination catalysts such as Co, Ti, V, Mo, Cr, and Fe. Currently, Co-based catalysts are used in commercial production, such as the diacetylacetone cobalt / triisobutylaluminum / carbon disulfide system produced by Ube Industries, Japan, as shown in US3778424A. They have also produced cis-butadiene-modified rubber containing meta-1,2-polybutadiene, under the grades Ubepol-VCR309 and Ubepol-VCR412. Modified cis-butadiene is mainly used in the automotive tire industry to improve compound strength and tire rolling performance.

[0004] Currently, iron catalysts are among the most studied catalytic systems. Early iron catalysts mainly used nitrogen-containing electron donors, which suffered from low activity and 1,2 stereoselectivity, as well as poor high-temperature stability. The application of ()phosphite electron donors has solved the problems of selectivity, activity, and stability of iron catalysts. However, similar to Co-based catalytic systems, highly crystalline sPBD is prone to precipitation, agglomeration, and entanglement during polymerization. When directly added to the rubber matrix as a filler, it exhibits poor dispersion and is prone to forming large agglomerates, resulting in insignificant reinforcing effects. Furthermore, because its melting point (160–180℃) is higher than the processing temperature, the polymer itself is prone to crosslinking under processing conditions, making it difficult to achieve high uniform dispersion at high filler contents, which seriously affects vulcanization performance and mechanical properties.

[0005] To achieve effective dispersion, it is necessary to synthesize polymer particles with micro- and nano-sized dimensions. Currently, the most common methods for synthesizing these micro- and nano-sized particles are suspension polymerization, emulsion polymerization, and supported polymerization. However, the co-catalysts used in coordination polymerization are generally water-sensitive, making suspension or emulsion polymerization methods difficult. Supported polymerization, in organic solvents, can conveniently synthesize polymers with specific morphologies. Summary of the Invention

[0006] The purpose of this invention is to overcome the problems existing in the prior art and provide an iron complex and its preparation method, an iron catalyst and its application, and a method for preparing polyolefins. The iron complex has good stability, the preparation method is simple and stable, and the iron catalyst made from it has stable catalytic performance. When catalyzing the polymerization of butadiene monomers, the polymer particles have small particle size, high crystallinity, and high selectivity for 1,2-structured polybutadiene.

[0007] To achieve the above objectives, the present invention provides an iron complex, characterized in that the iron complex has the structure shown in formula (1).

[0008]

[0009] Where R is selected from those containing The iron complex of the group, n is an integer from 1 to 6, and each R in formula (1) can be the same or different.

[0010] The second aspect of the present invention provides a method for preparing an iron complex, characterized in that the method includes: in the presence of an inert gas, mixing a compound with the structure shown in formula (4) with an organic solvent, an iron compound and an organic acid to react, and after the reaction is completed, performing solid-liquid separation, wherein the solid contains an iron complex;

[0011] The structure of equation (4) is as follows:

[0012] Where R0 is -(CH2). n NHCH2CH2NH2, where n is an integer from 1 to 6.

[0013] A third aspect of the present invention provides an iron complex prepared by the above-described method.

[0014] A fourth aspect of the present invention provides an iron catalyst, characterized in that the catalyst contains an iron complex, a phosphate ester and / or a phosphite, and an alkyl aluminum;

[0015] The iron complex is the iron complex described above.

[0016] The fifth aspect of the present invention provides an application of the above-described iron catalyst in olefin polymerization.

[0017] The sixth aspect of the present invention provides a method for preparing a polyolefin, characterized in that the method includes polymerizing the olefin under solution polymerization conditions and in the presence of an iron catalyst;

[0018] The iron catalyst is the iron catalyst described above.

[0019] Through the above technical solution, the present invention achieves at least the following beneficial effects:

[0020] (1) The method for preparing iron complexes in this invention is simple and convenient to operate;

[0021] (2) When the iron catalyst of the present invention is used to catalyze the polymerization of olefins, the catalytic performance is stable;

[0022] (3) When the iron catalyst of the present invention is used to catalyze the polymerization of butadiene monomer, the average particle size of the obtained polybutadiene particles is between 0.2 and 2.0 micrometers, and the obtained polybutadiene has a high content of 1,2-structure and high crystallinity. Detailed Implementation

[0023] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0024] In one aspect, the present invention provides an iron complex, characterized in that the iron complex has the structure shown in formula (1).

[0025]

[0026] Where R is selected from those containing Iron complexes of groups, where n is an integer from 1 to 6.

[0027] In this invention, R has the structure shown in formula (2) and / or the structure shown in formula (3).

[0028]

[0029]

[0030] Where n is an integer from 1 to 6,

[0031] Preferably, R1, R2, R4, and R5 are each independently selected from C1-C6 alkyl groups and their derivatives and / or C6-C20 aryl groups and their derivatives; R3 is selected from at least one of hydrogen, C1-C6 alkyl groups and their derivatives, and C6-C20 aryl groups and their derivatives; and R6 and R6' are each independently selected from C1-C20 alkyl groups and their derivatives and / or C6-C20 aryl groups and their derivatives.

[0032] In this invention, preferably, R1 and R4 are each independently selected from at least one of methyl, CF3, and phenyl; R2 and R5 are each independently selected from methyl and / or phenyl; and R3 is selected from hydrogen and / or methyl.

[0033] In this invention, more preferably, R1 and R4 are methyl, R2 and R5 are methyl; R1 and R4 are CF3, R2 and R5 are methyl; R1 and R4 are phenyl, R2 and R5 are phenyl; R1 and R4 are methyl, R2 and R5 are phenyl.

[0034] In this invention, preferably, R6 and R6' are each independently selected from at least one of isoheptyl, phenyl, methyl, neononyl, o-hydroxyphenyl, and heptadecanyl; more preferably, R6 and R6' are isoheptyl or phenyl.

[0035] The second aspect of the present invention provides a method for preparing an iron complex, characterized in that the method includes: in the presence of an inert gas, mixing a compound with the structure shown in formula (4) with an organic solvent, an iron compound and an organic acid to react, and after the reaction is completed, performing solid-liquid separation, wherein the solid contains an iron complex;

[0036] The structure of equation (4) is as follows:

[0037] Where R0 is -(CH2). n NHCH2CH2NH2, where n is an integer from 1 to 6.

[0038] In this invention, the compound with the structure of formula (4) can be synthesized according to methods known in the art, such as those described in the Journal of Applied Polymer Science, 2007, 103, 2608-2614.

[0039] In this invention, the iron compound is selected from compounds with structures shown in formula (5) and / or formula (6), wherein the structure of formula (5) is... The structure of equation (6) is as follows:

[0040] Wherein, R1, R2, R4, R5, R7, and R8 are each independently selected from alkyl groups and their derivatives of C1-C6 and / or aryl groups and their derivatives of C6-C20; R6, R6', and R6" are each independently selected from alkyl groups and their derivatives of C1-C20 and / or aryl groups and their derivatives of C6-C20.

[0041] In this invention, preferably, R1, R4, and R7 are each independently selected from at least one of methyl, CF3, and phenyl; R2, R5, and R8 are each independently selected from methyl and / or phenyl; more preferably, R1, R4, and R7 are methyl, and R2, R5, and R8 are methyl; R1, R4, and R7 are CF3, and R2, R5, and R8 are methyl; R1, R4, and R7 are phenyl, and R2, R5, and R8 are phenyl; R1, R4, and R7 are methyl, and R2, R5, and R8 are phenyl.

[0042] In this invention, preferably, R6, R6', and R6" are each independently selected from at least one of isoheptyl, phenyl, methyl, neononyl, o-hydroxyphenyl, and heptadecanyl; more preferably, R6, R6', and R6" are isoheptyl or phenyl; in particular, when R6, R6', and R6" are selected from the same substituent, the corresponding compounds are ferric isooctanoate, ferric benzoate, ferric acetate, ferric neodecanoate, ferric salicylate, and ferric stearate, respectively.

[0043] In this invention, the organic acid may be selected from organic acids with a structure such as R3-COOH, wherein R3 is at least one of hydrogen, C1-C6 alkyl groups and their derivatives, C6-C20 aryl groups and their derivatives, preferably at least one of formic acid, acetic acid, and benzoic acid, and more preferably formic acid and / or acetic acid.

[0044] In this invention, the R4 and R5 groups of the iron complex may also be provided by the R1 and R2 groups of an iron compound having the structure of formula (5); the R3 of the iron complex is provided by an organic acid.

[0045] In this invention, preferably, the organic solvent is selected from C1-C5 alcohols, preferably at least one of methanol, ethanol, isopropanol, and n-propanol, and more preferably methanol and / or ethanol.

[0046] In this invention, there is no particular limitation on the amount of organic solvent used, which varies according to the amount of compound with the structure shown in formula (4). In particular, when the amount of organic solvent used is such that the concentration of compound with the structure shown in formula (4) is 0.001-0.01 mol / L and the concentration of iron compound with the structure of formula (5) or formula (6) is 0.02-0.2 mol / L, the reaction proceeds smoothly and efficiently.

[0047] In this invention, the molar ratio of the compound with the structure shown in formula (4) to the iron compound can be 1:18-28, preferably 1:20-25.

[0048] In this invention, preferably, the molar ratio of the organic acid to the iron compound is 3-15:1, more preferably 5-10:1.

[0049] In this invention, there are no special limitations on the reaction conditions, as long as the reaction can proceed normally. Preferably, the reaction temperature is 50-120℃, more preferably 70-100℃; preferably, the reaction time is 12-120h, more preferably 24-96h.

[0050] In this invention, the method for preparing the iron complex further includes washing the iron complex contained in the obtained solid with an organic solvent one or more times, and then vacuum drying it; wherein the organic solvent used for washing can be selected from at least one of methanol, ethanol, isopropanol, and n-propanol; wherein the washing process is stopped when the filtrate becomes colorless and clear.

[0051] A third aspect of the present invention provides an iron complex prepared by the above-described method.

[0052] A fourth aspect of the present invention provides an iron catalyst, characterized in that the catalyst contains an iron complex, a phosphate ester and / or a phosphite, and an alkyl aluminum;

[0053] The iron complex is the iron complex described above.

[0054] In this invention, preferably, the alkylaluminum is selected from AlR9R. 10 R 11 Among them, R9 and R 10 R 11 Each of the same or different alkyl groups selected from hydrogen and / or C1-C5, more preferably at least one of triethylaluminum, diisobutylaluminum hydride, and triisobutylaluminum, and even more preferably triisobutylaluminum.

[0055] In this invention, the alkyl group in the phosphate ester and / or phosphite ester is selected from at least one of C1-C5 alkyl groups, unsubstituted or halogenated C6-C10 aryl groups, preferably at least one of diethyl phosphite, dibutyl phosphite, triphenyl phosphate, and tricresyl phosphate.

[0056] In this invention, it should be specifically noted that the structure of the phosphate ester is as follows: The structure of the phosphite is as follows: Wherein, the alkyl group in the above-mentioned phosphate esters and / or phosphites refers to R1', R2', R3', R1', R2' in the formula.

[0057] In this invention, the molar ratio of phosphate esters and / or phosphites, in molar amounts of phosphorus, to iron complexes, in molar amounts of iron, is 1-8:1, preferably 2-6:1.

[0058] In this invention, the molar ratio of the alkylaluminum to the iron complex is 10-80:1, more preferably 20-60:1, based on the molar amounts of their respective metal elements.

[0059] In this invention, "in terms of the molar amount of each metal element" means "the molar amount of a metal element in a substance represents the molar amount of the substance". For example, the molar amount of iron complex is represented by the molar amount of iron; the molar amount of alkyl aluminum is represented by the molar amount of aluminum.

[0060] The fifth aspect of the present invention provides an application of the above-described iron catalyst in olefin polymerization.

[0061] In this invention, the olefin can be a commonly used olefin in the art, including but not limited to C4-C6 conjugated dienes, such as butadiene, isoprene, 1,3-pentadiene, 1,3-hexadiene and 2,3-dimethylbutadiene.

[0062] The sixth aspect of the present invention provides a method for preparing a polyolefin, characterized in that the method includes polymerizing the olefin under solution polymerization conditions and in the presence of an iron catalyst;

[0063] The iron catalyst is the iron catalyst described above.

[0064] In this invention, the olefin can be a conjugated diene commonly used in the art, including but not limited to C4-C6 conjugated dienes, such as butadiene, isoprene, 1,3-pentadiene, 1,3-hexadiene and 2,3-dimethylbutadiene, preferably butadiene.

[0065] In this invention, the solution polymerization reaction conditions can be conventionally selected in the art, as long as the reaction can proceed normally. In particular, the solution polymerization reaction conditions may include: a temperature of 10-100℃, preferably 40-60℃; and a time of 0.5-12h, preferably 2-6h.

[0066] In this invention, the amount of iron catalyst is not particularly limited, as long as it can ensure that the reaction proceeds normally. For example, the molar ratio of butadiene to iron complex in terms of the molar amount of iron is 1000-6000:1.

[0067] In this invention, the solvent in the solution polymerization can be a commonly used solvent in the art, such as at least one of pentane, hexane, heptane, octane, n-hexane, cyclohexane, methylcyclohexane, toluene, xylene, and chlorobenzene.

[0068] In a preferred embodiment of the present invention, the method for preparing the polyolefin further includes: after the polymerization reaction is completed, the active polymer chain can be deactivated by adding a terminator-antioxidant to terminate the polymerization reaction and prevent aging and deterioration of the raw rubber during preparation and storage.

[0069] In a preferred embodiment of the present invention, the amount of the terminator-antioxidant mixed solution can be within the commonly used range in the art. For example, relative to 1g butadiene, the amount of the terminator-antioxidant is 100-120mL, and the mass concentration of the antioxidant can be 1-5% by weight.

[0070] In a preferred embodiment of the present invention, the antioxidant can be a commonly used antioxidant in the art, for example, the antioxidant can be at least one of 2,6-di-tert-butyl-p-methylphenol, 2-sec-butyl-4,6-dinitrophenol, 2,4-bis(n-octylthionyl)-6-methylphenol, trinonylphenyl phosphite, pentaerythritol tetrakis[β-(3',5')-di-tert-butyl-4'-hydroxyphenyl]propionate, octadecyl β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, and 2,2'-methylenebis-(4-methyl-6-tert-butylphenol).

[0071] In a preferred embodiment of the present invention, the type of terminator can be a conventional choice in the art and is not particularly limited, as long as the terminator can deactivate the polymer chain with active end groups. Generally, the terminator can be selected from water, C1-C6 aliphatic alcohols, C4-C6 aliphatic alcohols, etc. 12 At least one of aliphatic carboxylic acids and aryl hydroxyl compounds; wherein the aryl hydroxyl compound refers to a compound formed by replacing at least one hydrogen atom on the benzene ring with a hydroxyl group; preferably, the terminator is at least one of water, methanol, ethanol and isopropanol.

[0072] In a preferred embodiment of the present invention, the terminator-antioxidant is ethanol-2,6-di-tert-butyl-p-methylphenol.

[0073] In a preferred embodiment of the present invention, in order to remove residual Fe 2+ To prevent Fe 2+ The effect on polymer properties can be mitigated by adding a small amount of hydrochloric acid to the above-mentioned terminator-antioxidant; wherein the volume ratio of hydrochloric acid to terminator can be 1:40-120, preferably 1:50-100.

[0074] In this invention, after the polymerization reaction is terminated, the polymer solution obtained by polymerization can be precipitated, washed and dried using conventional methods in the art to obtain the polymerization product.

[0075] The present invention will be described in detail below through embodiments. In the following embodiments,

[0076] Ferric acetylacetone, n-hexane, tetrahydrofuran, and triisobutylaluminum are commercially available from Bailingwei; diethyl phosphite, 1,1,1-trifluoro-2,4-pentanedione, dibenzoylmethane, and benzoylacetone are commercially available from Anaiji; butadiene is an industrial product from Yanshan Petrochemical; sodium hydride, anhydrous ferric chloride, ferric isooctanoate, ferric benzoate, formic acid, acetic acid, cyclohexane, toluene, 2,6-di-tert-butyl-4-methylphenol, hydrochloric acid, methanol, ethanol, and acetylacetaldehyde are commercially available from Inokai; and triphenyl phosphate is a commercially available product from Acros.

[0077] The compound with the structure of formula (4) was prepared by the method described in the Journal of Applied Polymer Science, 2007, 103, 2608-2614.

[0078] The content and composition of the 1,2 and 1,4 structures of the polymer were determined using a Bruker 400MHz nuclear magnetic resonance spectrometer (Germany). 1 HNMR and 13 CNMR analysis was performed using deuterated o-dichlorobenzene as the solvent at a temperature of 110°C.

[0079] The C, H, N, and O contents in the iron complex were determined using a Vario ELⅢ elemental analyzer; the iron and silicon contents of the iron complex were determined using a Nanoc Plasma 1000 inductively coupled plasma atomic emission spectrometer. The solid was dissolved in nitric acid before testing.

[0080] The particle size of polybutadiene was determined by diluting the butadiene polymerization solution several times and measuring it using a Malvern Panalytical Mastersizer 3000 particle size distribution instrument.

[0081] The crystallinity of polybutadiene was determined using an X-ray diffractometer D8 Advance, according to the reference "Zhang Hongfang, Mo Zhishen, et al., Polymer Communications, 1986, 3: 193-196".

[0082] Example 1

[0083] (1) Preparation of iron compound Fe-1

[0084] Prepare two 100mL ground glass stoppered reaction flasks, bake them, and remove the solution three times. In one flask, add acetylacetone (0.5006g, 5mmol) and 20mL of purified tetrahydrofuran. After complete dissolution, slowly add sodium hydride (0.144g, 6mmol) in batches under an inert gas atmosphere, and react for 4 hours. In the other flask, add anhydrous ferric chloride and 15mL of tetrahydrofuran. After complete dissolution, slowly pump the acetylacetone-tetrahydrofuran reaction solution into the ferric chloride-tetrahydrofuran solution, and react for 12 hours. After the reaction is complete, remove the solvent by rotary evaporation to obtain a red viscous liquid. Add n-hexane and stir for 24 hours. Filter, wash, and dry to obtain a reddish-brown powder. Recrystallize from a mixture of tetrahydrofuran and n-hexane to obtain the pure product.

[0085] (2) Preparation of iron complex C1

[0086] A 150ml round-bottom flask was baked and the mixture was changed three times under Ar protection. 0.34g (0.28mmol) of the compound with structure (4) and 50mL of anhydrous methanol were added to the flask, and the mixture was stirred until dissolved. Then, 2.04g (5.77mmol) of Fe-1 and 1.41g (30.6mmol) of formic acid were added, and the mixture was heated at 75°C for 52 hours, resulting in the formation of a large amount of precipitate. The collected solid was filtered, washed three times with methanol, and dried under vacuum. The iron complex C1 was obtained as a light red powder with a yield of 79.1%.

[0087] The iron complex C1 was characterized using an elemental analyzer, yielding a C content of 38.04 wt%, a H content of 4.99 wt%, a N content of 5.55 wt%, an O content of 23.75 wt%, a Si content of 5.56 wt%, and an Fe content of 22.11 wt%. Based on this, its structure was determined to be as follows:

[0088] Where R is

[0089] Example 2

[0090] (1) Preparation of iron compound Fe-2

[0091] Iron compound Fe-2 was prepared according to the preparation method of Example 1, except that 0.5006 g of acetylacetone (5 mmol) was replaced with 0.77 g of 1,1,1-trifluoro-2,4-pentanedione (5 mmol), and the tetrahydrofuran reaction solution of 1,1,1-trifluoro-2,4-pentanedione was slowly pumped into another reaction flask with a ground glass joint containing a completely dissolved tetrahydrofuran solution of ferric chloride.

[0092] (2) Preparation of iron complex C2

[0093] A 150ml round-bottom flask was baked and the mixture was changed three times under Ar protection. 0.34g (0.28mmol) of the compound with structure (4) and 60mL of anhydrous methanol were added to the flask, and the mixture was stirred until the compound with structure (4) dissolved. Then, 3.09g (6.02mmol) of Fe-2 and 1.72g (37.3mmol) of formic acid were added. The mixture was heated at 75°C for 32 hours, resulting in the formation of a large amount of precipitate. The solid was collected by filtration, washed three times with methanol, and dried under vacuum. The iron complex C2 was obtained as an orange powder with a yield of 79.1%.

[0094] The iron complex C2 was characterized using an elemental analyzer, yielding a C content of 31.34 wt%, a H content of 3.12 wt%, a N content of 4.57 wt%, an O content of 19.57 wt%, a Si content of 4.58 wt%, and an Fe content of 18.22 wt%. Based on this, its structure was determined to be as follows:

[0095] Where R is

[0096] Example 3

[0097] (1) Preparation of iron compound Fe-3

[0098] The iron compound Fe-3 was prepared according to the preparation method of Example 1, except that 0.5006 g of acetylacetone (5 mmol) was replaced with 1.12 g of dibenzoylmethane (5 mmol), and the tetrahydrofuran reaction solution of dibenzoylmethane was slowly pumped into another reaction flask with a ground glass joint containing a completely dissolved tetrahydrofuran solution of ferric chloride.

[0099] (2) Preparation of iron complex C3

[0100] A 150 mL round-bottom flask was baked and evacuated three times. Under Ar protection, 0.34 g (0.28 mmol) of the compound with structure (4) and 70 mL of anhydrous methanol were added to the round-bottom flask, and the mixture was stirred until the compound with structure (4) dissolved. Then, 4.50 g (6.19 mmol) of Fe-3 and 2.11 g (45.8 mmol) of formic acid were added, and the mixture was heated at 75 °C for 84 hours, resulting in the formation of a large amount of precipitate. The solid obtained was collected by filtration, washed three times with methanol, and dried under vacuum. The iron complex C3 was obtained as an orange-red powder with a yield of 66.4%.

[0101] The iron complex C3 was characterized using an elemental analyzer, yielding a C content of 57.39 wt%, a H content of 4.41 wt%, a N content of 3.72 wt%, an O content of 15.93 wt%, a Si content of 3.73 wt%, and a Fe content of 14.82 wt%. Based on this, its structure was determined to be as follows:

[0102] Where R is

[0103] Example 4

[0104] (1) Preparation of iron compound Fe-4

[0105] The iron compound Fe-4 was prepared according to the preparation method of Example 1, except that 0.5006 g of acetylacetone (5 mmol) was replaced with 0.81 g of benzoylacetone (5 mmol), and the tetrahydrofuran reaction solution of benzoylacetone was slowly pumped into another reaction flask with a ground glass joint containing a completely dissolved tetrahydrofuran solution of ferric chloride.

[0106] (2) Preparation of iron complex C4

[0107] A 150ml round-bottom flask was baked and the mixture was changed three times under Ar protection. 0.34g (0.28mmol) of the compound with structure (4) and 75mL of anhydrous methanol were added to the flask, and the mixture was stirred until dissolved. Then, 3.53g (6.55mmol) of Fe-4 and 3.14g (52.4mmol) of acetic acid were added. The mixture was heated at 75°C for 72 hours, resulting in the formation of a large amount of precipitate. The collected solid was filtered, washed three times with methanol, and dried under vacuum. The iron complex C4 was obtained as a light red powder with a yield of 82.2%.

[0108] The iron complex C4 was characterized using an elemental analyzer, yielding a C content of 50.41 wt%, a H content of 4.86 wt%, a N content of 4.35 wt%, an O content of 18.65 wt%, a Si content of 4.37 wt%, and a Fe content of 17.36 wt%. Based on this, its structure was determined to be as follows:

[0109] Where R is

[0110] Example 5

[0111] (1) Preparation of iron compounds

[0112] The iron compound selected is ferrous isooctanoate.

[0113] (2) Preparation of iron complex C5

[0114] A 150 ml round-bottom flask was baked and the mixture was changed three times under Ar protection. 0.34 g (0.28 mmol) of the compound with structure (4) and 70 mL of anhydrous ethanol were added to the flask, and the mixture was stirred until dissolved. Then, 3.24 g (6.69 mmol) of ferric isooctanoate and 2.65 g (57.5 mmol) of formic acid were added. The mixture was heated at 85 °C for 72 hours, resulting in the formation of a large amount of precipitate. The solid was collected by filtration, washed three times with ethanol, and dried under vacuum. The iron complex C5 was obtained as a pale orange powder with a yield of 75.3%.

[0115] The iron complex C5 was characterized using an elemental analyzer, yielding a C content of 44.53 wt%, a H content of 6.96 wt%, a N content of 4.72 wt%, an O content of 20.22 wt%, a Si content of 4.73 wt%, and an Fe content of 18.82 wt%. Based on this, its structure was determined to be as follows:

[0116] Where R is

[0117] Example 6

[0118] (1) Preparation of iron compounds

[0119] Ferric benzoate was selected as the iron compound.

[0120] (2) Preparation of iron complex C6

[0121] A 150 mL round-bottom flask was baked and evacuated three times. Under Ar protection, 0.34 g (0.28 mmol) of the compound with structure (4) and 50 mL of anhydrous ethanol were added to the flask, and the mixture was stirred until the compound with structure (4) dissolved. Then, 2.89 g (6.89 mmol) of ferric benzoate and 3.89 g (64.8 mmol) of acetic acid were added, and the mixture was heated at 85 °C for 92 hours, resulting in the formation of a large amount of precipitate. The solid was collected by filtration, washed three times with ethanol, and dried under vacuum. The iron complex C6 was obtained as a dark red powder with a yield of 83.4%.

[0122] The iron complex C6 was characterized using an elemental analyzer, yielding a C content of 44.78 wt%, a H content of 4.12 wt%, a N content of 4.97 wt%, an O content of 21.31 wt%, a Si content of 4.99 wt%, and an Fe content of 19.83 wt%. Based on this, its structure was determined to be as follows:

[0123] Where R is

[0124] Example 7

[0125] (1) Preparation of iron compound Fe-7

[0126] The iron compound Fe-7 was prepared according to the preparation method of Example 1, except that 0.5006 g of acetylacetone (5 mmol) was replaced with 0.43 g of acetylacetal (5 mmol), and the tetrahydrofuran reaction solution of acetylacetal was slowly pumped into another reaction flask with a ground glass joint containing a completely dissolved tetrahydrofuran solution of ferric chloride.

[0127] (2) Preparation of iron complex C7

[0128] A 150 ml round-bottom flask was baked and the mixture was changed three times under Ar protection. 0.34 g (0.28 mmol) of the compound with structure (4) and 50 mL of anhydrous ethanol were added to the flask, and the mixture was stirred until the compound with structure (4) dissolved. Then, 1.93 g (6.22 mmol) of Fe-7 and 1.41 g (30.6 mmol) of formic acid were added, and the mixture was heated at 75 °C for 52 hours, resulting in the formation of a large amount of precipitate. The obtained solid was collected by filtration, washed three times with methanol, and dried under vacuum. The iron complex C7 was obtained as a light red powder with a yield of 51.8%.

[0129] The iron complex C7 was characterized using an elemental analyzer, yielding a C content of 35.29 wt%, a H content of 4.20 wt%, a N content of 5.88 wt%, an O content of 25.21 wt%, a Si content of 5.89 wt%, and a Fe content of 23.53 wt%. Based on this, its structure was determined to be as follows:

[0130] Where R is

[0131] Example 8

[0132] Iron complex C8 was prepared according to the preparation method of Example 1, except that the compound R0 of formula (4) in Example 1 was replaced with -(CH2)6NHCH2CH2NH2 to obtain iron complex C9, which was a light red powder with a yield of 82.2%.

[0133] The iron complex C8 was characterized using an elemental analyzer, yielding a C content of 41.70 wt%, a H content of 5.71 wt%, a N content of 5.12 wt%, an O content of 21.93 wt%, a Si content of 5.13 wt%, and an Fe content of 20.41 wt%. Based on this, its structure was determined to be as follows:

[0134] Where R is

[0135] Comparative Example 1

[0136] Iron complex C9 was prepared according to the preparation method of Example 1, except that the compound R0 of formula (4) in Example 1 was replaced with -(CH2)7NHCH2CH2NH2 to obtain iron complex C9, which was a light red powder with a yield of 79.3%.

[0137] The iron complex C9 was characterized using an elemental analyzer, yielding a C content of 42.80 wt%, a H content of 5.93 wt%, a N content of 4.99 wt%, an O content of 21.38 wt%, a Si content of 5.00 wt%, and an Fe content of 19.90 wt%. Based on this, its structure was determined to be as follows:

[0138] Where R is

[0139] Application Example 1

[0140] A 200 mL ampoule was baked under vacuum and purged with argon. Then, 12.6 mg of the iron complex C1 prepared in Example 1 (containing 0.05 mmol of iron) and a solution consisting of 10.8 g butadiene (200 mmol) and 90 mL of anhydrous n-hexane were added sequentially. Next, 27.6 mg of diethyl phosphite (0.2 mmol) was added, followed by 2 mL of a 1.0 mol / L triisobutylaluminum (2 mmol) hexane solution. The resulting mixture was placed in a 50°C constant temperature bath for reaction. After 4 hours of reaction, the polymerization reaction was terminated with 100 mL of a 1% (w / w) hydrochloric acid / ethanol solution of 2,6-di-tert-butyl-4-methylphenol (hydrochloric acid to ethanol volume ratio 1:50). The resulting polymer was precipitated with ethanol, repeatedly washed, and then vacuum dried at 40°C to constant weight, yielding 8.25 g of polybutadiene with a monomer conversion rate of 76.4%. The structure, average particle size, and crystallinity of the obtained polybutadiene are shown in Table 1.

[0141] Application Example 2

[0142] A 200 mL ampoule was baked under vacuum and purged with argon. Then, 15.3 mg of the iron complex C2 prepared in Example 2 (containing 0.05 mmol of iron) and a solution consisting of 13.5 g butadiene (250 mmol) and 110 mL of anhydrous n-hexane were added sequentially. Then, 20.7 mg of diethyl phosphite (0.15 mmol) was added, followed by 1.75 mL of a 1.0 mol / L triisobutylaluminum (1.75 mmol) hexane solution. The resulting mixture was placed in a 55 °C constant temperature bath for reaction. After 4.5 h of reaction, the polymerization reaction was terminated with 100 mL of a 1 wt% hydrochloric acid / ethanol solution of 2,6-di-tert-butyl-4-methylphenol (hydrochloric acid to ethanol volume ratio of 1:50). The resulting polymer was precipitated with ethanol, repeatedly washed, and then vacuum dried at 40 °C to constant weight to obtain 10.98 g of polybutadiene with a monomer conversion rate of 81.3%. The structure, average particle size, and crystallinity of the obtained polybutadiene are shown in Table 1.

[0143] Application Example 3

[0144] A 200 mL ampoule was baked under vacuum and purged with argon. Then, 18.8 mg of the iron complex C3 prepared in Example 3 (containing 0.05 mmol of iron) and a solution consisting of 7.29 g butadiene (135 mmol) and 60 mL of anhydrous n-hexane were added sequentially. Next, 52.2 mg of triphenyl phosphate (0.16 mmol) was added, followed by 1.5 mL of a 1.0 mol / L triisobutylaluminum (1.5 mmol) hexane solution. The resulting mixture was placed in a 45°C constant temperature bath for reaction. After 3 hours of reaction, the polymerization reaction was terminated with 100 mL of a 1% (w / w) hydrochloric acid / ethanol solution of 2,6-di-tert-butyl-4-methylphenol (hydrochloric acid to ethanol volume ratio 1:50). The resulting polymer was precipitated with ethanol, repeatedly washed, and then vacuum dried at 40°C to constant weight, yielding 5.02 g of polybutadiene with a monomer conversion rate of 68.9%. The structure, average particle size, and crystallinity of the obtained polybutadiene are shown in Table 1.

[0145] Application Example 4

[0146] A 200 mL ampoule was baked under vacuum and purged with argon. Then, 16.1 mg of the iron complex C4 prepared in Example 4 (containing 0.05 mmol of iron) and a solution consisting of 12.15 g butadiene (225 mmol) and 90 mL of anhydrous n-hexane were added sequentially. Next, 42.7 mg of dibutyl phosphite (0.22 mmol) was added, followed by 2.25 mL of a 1.0 mol / L triisobutylaluminum (2.25 mmol) hexane solution. The resulting mixture was placed in a 48°C constant temperature bath for 3.5 h. The polymerization reaction was terminated with 100 mL of a 3% (w / w) hydrochloric acid / ethanol solution of 2,6-di-tert-butyl-4-methylphenol (hydrochloric acid to ethanol volume ratio 1:50). The resulting polymer was precipitated with ethanol, repeatedly washed, and then vacuum dried at 40°C to constant weight, yielding 8.97 g of polybutadiene with a monomer conversion rate of 73.8%. The structure, average particle size, and crystallinity of the obtained polybutadiene are shown in Table 1.

[0147] Application Example 5

[0148] A 100 mL ampoule was baked under vacuum and purged with argon. Then, 14.8 mg of the iron complex C5 prepared in Example 5 (containing 0.05 mmol of iron) and a solution consisting of 4.32 g butadiene (80 mmol) and 40 mL of anhydrous n-hexane were added sequentially. Next, 45.7 mg of triphenyl phosphate (0.14 mmol) was added, followed by 1.25 mL of a 1.0 mol / L triisobutylaluminum (1.25 mmol) hexane solution. The resulting mixture was placed in a 53°C constant temperature bath for 2.8 h. The polymerization reaction was terminated with 70 mL of a 1% (w / w) hydrochloric acid / ethanol solution of 2,6-di-tert-butyl-4-methylphenol (hydrochloric acid to ethanol volume ratio 1:50). The resulting polymer was precipitated with ethanol, repeatedly washed, and then vacuum dried at 40°C to constant weight, yielding 3.07 g of polybutadiene with a monomer conversion rate of 71.1%. The structure, average particle size, and crystallinity of the obtained polybutadiene are shown in Table 1.

[0149] Application Example 6

[0150] A 200 mL ampoule was baked under vacuum and purged with argon. Then, 14.1 mg of the iron complex C6 prepared in Example 6 (containing 0.05 mmol of iron) and a solution consisting of 8.64 g butadiene (160 mmol) and 70 mL of anhydrous n-hexane were added sequentially. Next, 50.5 mg of dibutyl phosphite (0.26 mmol) was added, followed by 2.5 mL of a 1.0 mol / L triisobutylaluminum (2.5 mmol) hexane solution. The resulting mixture was placed in a 58°C constant temperature bath for 5.7 h. The polymerization reaction was terminated with 100 mL of a 2% (w / w) hydrochloric acid / ethanol solution of 2,6-di-tert-butyl-4-methylphenol (hydrochloric acid to ethanol volume ratio 1:50). The resulting polymer was precipitated with ethanol, repeatedly washed, and then vacuum dried at 40°C to constant weight, yielding 7.29 g of polybutadiene with a monomer conversion rate of 84.4%. The structure, average particle size, and crystallinity of the obtained polybutadiene are shown in Table 1.

[0151] Application Example 7

[0152] A 200 mL ampoule was baked under vacuum and purged with argon. Then, 12.6 mg of the iron complex C1 prepared in Example 1 (containing 0.05 mmol of iron) and a solution consisting of 10.8 g butadiene (200 mmol) and 90 mL of anhydrous cyclohexane were added sequentially. Next, 27.6 mg of diethyl phosphite (0.2 mmol) was added, followed by 2.3 mL of a 1.0 mol / L triisobutylaluminum (2.3 mmol) hexane solution. The resulting mixture was placed in a 55°C constant temperature bath for reaction. After 4 hours of reaction, the polymerization reaction was terminated with 100 mL of a 1% (w / w) hydrochloric acid / ethanol solution of 2,6-di-tert-butyl-4-methylphenol (hydrochloric acid to ethanol volume ratio 1:50). The resulting polymer was precipitated with ethanol, repeatedly washed, and then vacuum dried at 40°C to constant weight, yielding 8.19 g of polybutadiene with a monomer conversion rate of 75.8%. The structure, average particle size, and crystallinity of the obtained polybutadiene are shown in Table 1.

[0153] Application Example 8

[0154] A 200 mL ampoule was baked under vacuum and purged with argon. Then, 12.6 mg of the iron complex C1 prepared in Example 1 (containing 0.05 mmol of iron) and a solution consisting of 10.8 g butadiene (200 mmol) and 90 mL of anhydrous toluene were added sequentially. Next, 27.6 mg of diethyl phosphite (0.2 mmol) was added, followed by 2.2 mL of a 1.0 mol / L toluene solution of triisobutylaluminum (2.2 mmol). The resulting mixture was placed in a 53°C constant temperature bath for reaction. After 4 h of reaction, the polymerization reaction was terminated with 100 mL of a 1% (w / w) hydrochloric acid / ethanol solution of 2,6-di-tert-butyl-4-methylphenol (hydrochloric acid to ethanol volume ratio 1:50). The resulting polymer was precipitated with ethanol, repeatedly washed, and then vacuum dried at 40°C to constant weight, yielding 8.34 g of polybutadiene with a monomer conversion rate of 77.2%. The structure, average particle size, and crystallinity of the obtained polybutadiene are shown in Table 1.

[0155] Application Example 9

[0156] A 200 mL ampoule was baked under vacuum and then purged with argon. A solution consisting of 7.7 mg of the iron complex C2 prepared in Example 2 (containing 0.025 mmol of iron) and 8.0 mg of the iron complex C4 prepared in Example 4 (containing 0.025 mmol of iron), 8.1 g of butadiene (150 mmol), and 80 mL of anhydrous n-hexane was then added. Finally, 13.8 mg of diethyl phosphite (0.1 mmol) and 19.4 mg of dibutyl phosphite (0.1 mmol) were added. Then, 1.75 mL of a 1.0 mol / L triisobutylaluminum (1.75 mmol) hexane solution was added, and the resulting mixture was placed in a 50 °C constant temperature bath for reaction. After 4.5 h of reaction, the polymerization reaction was terminated with 100 mL of a 1 wt% hydrochloric acid / ethanol solution of 2,6-di-tert-butyl-4-methylphenol (hydrochloric acid to ethanol volume ratio of 1:50). The obtained polymer was precipitated with ethanol, repeatedly washed, and then vacuum dried at 40 °C to constant weight to obtain 5.11 g of polybutadiene, with a monomer conversion rate of 63.1%. The structure, average particle size, and crystallinity of the obtained polybutadiene are shown in Table 1.

[0157] Application Example 10

[0158] Polybutadiene was prepared according to the method of Application Example 1, except that 12.6 mg of the iron complex C1 (containing 0.05 mmol of iron) prepared in Example 1 was replaced with 11.9 mg of the iron complex C7 (containing 0.05 mmol of iron). A total of 4.81 g of polybutadiene was obtained, with a monomer conversion rate of 44.5%. The structure, average particle size, and crystallinity of the obtained polybutadiene are shown in Table 1.

[0159] Application Example 11

[0160] Polybutadiene was prepared according to the method of Application Example 1, except that 12.6 mg of the iron complex C1 (containing 0.05 mmol of iron) prepared in Example 1 was replaced with 13.7 mg of the iron complex C8 (containing 0.05 mmol of iron). A total of 5.42 g of polybutadiene was obtained, with a monomer conversion rate of 50.2%. The structure, average particle size, and crystallinity of the obtained polybutadiene are shown in Table 1.

[0161] Application Comparative Example 1

[0162] Polybutadiene was prepared according to the method of Application Example 1, except that 12.6 mg of the iron complex C1 (containing 0.05 mmol of iron) prepared in Example 1 was replaced with 14.0 mg of the iron complex C9 (containing 0.05 mmol of iron). A total of 5.22 g of polybutadiene was obtained, with a monomer conversion rate of 48.4%. The structure, average particle size, and crystallinity of the obtained polybutadiene are shown in Table 1.

[0163] Application Comparative Example 2

[0164] A 200 mL ampoule was baked under vacuum and purged with argon. Then, 7.1 mg (0.02 mmol) of triacetylacetone iron, 3.24 g (60 mmol) of butadiene, and 40 mL of anhydrous hexane were added sequentially. Next, 11.0 mg (0.08 mmol) of diethyl phosphite was added, followed by 0.8 mL of a 1 mol / L solution of triisobutylaluminum (0.8 mmol) in hexane. The mixture was placed in a 50 °C constant temperature bath for 5 h. The polymerization reaction was terminated with 60 mL of a 2% (w / w) hydrochloric acid / ethanol solution of 2,6-di-tert-butyl-4-methylphenol (hydrochloric acid to ethanol volume ratio 1:100). The resulting polymer was precipitated with ethanol, repeatedly washed, and then vacuum dried at 40 °C to constant weight, yielding 2.45 g of polybutadiene with a monomer conversion rate of 75.6%. The structure, average particle size, and crystallinity of the obtained polybutadiene are shown in Table 1.

[0165] Table 1

[0166]

[0167]

[0168] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. An iron complex characterized in that, The iron complex has a structure shown in formula (1), wherein R is selected from the group consisting of iron complexes of radicals, n is an integer from 1 to 6, and each R is the same or different.

2. The iron complex according to claim 1, characterized in that, The R has a structure shown in formula (2) and / or a structure shown in formula (3), wherein n is an integer of 1-6, Wherein, the R1, R2, R4, R5 are each independently selected from C1-C6 alkyl and its derivatives and / or C6-C20 aryl and its derivatives; the R3 is selected from at least one of hydrogen, C1-C6 alkyl and its derivatives, C6-C20 aryl and its derivatives; the R6 and R6' are each independently selected from C1-C20 alkyl and its derivatives and / or C6-C20 aryl and its derivatives; Preferably, the R1 and R4 are each independently selected from at least one of methyl, CF3, phenyl; the R2 and R5 are each independently selected from methyl and / or phenyl; the R3 is selected from hydrogen and / or methyl; the R6 and R6' are each independently selected from at least one of isoheptyl, phenyl, methyl, neononyl, ortho-hydroxyphenyl, heptadecyl; more preferably, the R1 and R4 are methyl, the R2 and R5 are methyl; the R1 and R4 are CF3, the R2 and R5 are methyl; the R1 and R4 are phenyl, the R2 and R5 are phenyl; the R1 and R4 are methyl, the R2 and R5 are phenyl; the R6 and R6' are isoheptyl or phenyl.

3. A process for the preparation of an iron complex, characterized in that, The method comprises: mixing a compound having a structure shown in formula (4) with an organic solvent, an iron compound and an organic acid in the presence of an inert gas, and after the reaction is completed, performing solid-liquid separation, and the solid contains the iron complex; wherein R0is -(CH2) n NHCH2CH2NH2, n is an integer from 1 to 6.

4. The preparation method according to claim 3, characterized in that, The iron compound is selected from a compound having a structure shown in formula (5) and / or formula (6), Wherein, the R1, R2, R4, R5, R7, R8 are each independently selected from C1-C6 alkyl and its derivatives and / or C6-C20 aryl and its derivatives; the R6, R6', R6'' are each independently selected from C1-C20 alkyl and its derivatives and / or C6-C20 aryl and its derivatives; Preferably, the R1, R4, R7 are each independently selected from at least one of methyl, CF3, phenyl; the R2, R5, R8 are each independently selected from methyl and / or phenyl; the R6, R6', R6'' are each independently selected from at least one of isoheptyl, phenyl, methyl, neononyl, ortho-hydroxyphenyl, heptadecyl; more preferably, the R1, R4, R7 are methyl, the R2, R5, R8 are methyl; the R1, R4, R7 are CF3, the R2, R5, R8 are methyl; the R1, R4, R7 are phenyl, the R2, R5, R8 are phenyl; the R1, R4, R7 are methyl, the R2, R5, R8 are phenyl; the R6, R6', R6'' are isoheptyl or phenyl.

5. The production method according to claim 3 or 4, characterized by, The organic acid is selected from an organic acid having a structure as shown in R3-COOH, wherein R3 is at least one of hydrogen, C1-C6 alkyl and its derivatives, C6-C20 aryl and its derivatives; Preferably, the organic acid is selected from at least one of formic acid, acetic acid, benzoic acid, more preferably formic acid and / or acetic acid; and / or the organic solvent is selected from at least one of C1-C5 alcohols, preferably methanol, ethanol, isopropanol, n-propanol, more preferably methanol and / or ethanol.

6. The method of any one of claims 3-5, wherein, the molar ratio of the compound of formula (4) to the iron compound is 1:18-28, preferably 1:20-25; and / or the molar ratio of the organic acid to the iron compound is 3-15:1, preferably 5-10:

1.

7. The method of any one of claims 3-6, wherein, the reaction temperature is 50-120℃, preferably 70-100℃; and the reaction time is 12-120h, preferably 24-96h.

8. The iron complex prepared by the method of any one of claims 3-7.

9. An iron catalyst characterized in that, the catalyst comprises the iron complex, a phosphorus ester and / or phosphite, and an alkyl aluminum; wherein the iron complex is the iron complex of any one of claims 1, 2, or 8.

10. The iron catalyst according to claim 9, characterized in that the alkyl group in the phosphorus ester and / or phosphite is selected from at least one of C1-C5 alkyl groups, unsubstituted or halogen-substituted C6-C10 aryl groups, preferably at least one of diethyl phosphite, dibutyl phosphite, triphenyl phosphate, and tritolyl phosphate; Preferably, the aluminum alkyl is selected from the group consisting of AlR9R 10 R 11 wherein R9, R 10 , R 11 are each the same or different selected from the group consisting of hydrogen and / or a C1-C5 alkyl, more preferably at least one of triethylaluminum, diisobutylaluminum hydride, triisobutylaluminum, further preferably triisobutylaluminum.

11. The iron catalyst according to claim 9 or 10, characterized in that the molar ratio of the phosphorus ester and / or phosphite to the iron complex, based on the molar amount of phosphorus to the molar amount of iron, is 1-8:1, preferably 2-6:1; preferably, the molar ratio of the alkyl aluminum to the iron complex, based on the molar amount of each metal element, is 10-80:1, more preferably 20-60:

1.

12. Use of the iron catalyst of any one of claims 9-11 in the polymerization of olefins.

13. A process for the preparation of a polyolefin, characterized in that, The method comprises polymerizing an olefin in the presence of the iron catalyst under solution polymerization conditions. wherein the iron catalyst is the iron catalyst of any one of claims 9-11.

14. The method of claim 13, wherein, the olefin is a conjugated diene, preferably butadiene.

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