PCNSiP ligand and preparation method thereof, catalytic system containing the ligand and application thereof

Abstract

The invention discloses a PCNSiP ligand and a preparation method thereof, a catalytic system comprising the ligand and application thereof in preparing alpha-olefins by ethylene polymerization, belonging to the field of metal organic catalysts. The structural formula of the ligand is shown in Formula I: #imgabs0# wherein C m is selected from alkylene, substituted alkylene, arylene, substituted arylene, m represents the number of bridging carbon atoms, m is 1 to 20; R 1 , R 2 , R 3 , R 4 R is independently selected from a linear alkyl group, a branched alkyl group, a cycloalkyl group, a substituted cycloalkyl group, an aryl group, and a substituted aryl group; 5 , R 6 The PCNSiP ligand of the present invention, transition metal and co-catalyst form a catalytic system that can catalyze the polymerization of ethylene to obtain α-olefins with high activity and high selectivity.

Description

Technical Field

[0001] The present invention relates to the field of metal organic catalysts, and in particular to a ligand for ethylene oligomerization catalysis and a preparation method thereof, a catalytic system containing the ligand and application thereof in preparing alpha-olefins by ethylene oligomerization. Background Art

[0002] Linear α-olefins (LAOs) are a very important class of organic raw materials and chemical intermediates, which are widely used in the synthesis of copolymerized polyethylene, surfactants, advanced synthetic lubricants (polyα-olefins), plasticizers and fine chemicals. 1-Hexene and 1-octene are the two most valuable LAOs in terms of research and economic value, and are mainly used as comonomers in the production of linear low-density polyethylene (LLDPE), high-density polyethylene (HDPE) and polyolefin elastomers (POE). 1-Hexene or 1-octene copolymerized polyolefins have good impact resistance, tear resistance and tensile strength, which are difficult to match with 1-butene copolymers and have broad development prospects.

[0003] Compared with traditional methods such as wax cracking, extraction separation, alkane catalytic cracking, alkane dehydrogenation, coal extraction, fatty alcohol dehydrogenation, and internal olefin isomerization, ethylene selective polymerization to produce 1-hexene and 1-octene provides a clean and efficient path.

[0004] In 2004, Bollmann et al. (J. AM. CHEM. SOC. 2004, 126, 14712-14713) of Sasol Company first realized the highly selective polymerization of ethylene to prepare 1-octene and 1-hexene. The Cr / PNP / MAO catalytic system was used, the catalyst was composed of a trivalent chromium precursor and a PNP ligand, MAO was a co-catalyst, toluene or alkanes were used as solvents, the reaction temperature was 45°C, and the ethylene pressure was 4.5 MPa. The selectivity of 1-octene reached 70%, the selectivity of 1-hexene reached 13%, and the catalyst activity was about 300kg / (g Cr). Sasol then applied for a series of patents related to ethylene polymerization, such as the following patent documents: CN105263890A, CN104220402A, CN105228973A, CN105228974A, CN101052605A, etc., and in 2014 achieved industrial production of 1-octene by selective tetramerization of ethylene.

[0005] At present, the ligand skeletons used in the catalysts for selective polymerization of ethylene mainly include PNP, PCCP, PCSiCP, PNCN and various derived ligands. The steric hindrance effect and electronic effect of the ligand have a great influence on the catalyst activity and product selectivity. Patent documents US8609924B2, CN105562096A, CN105562095A, CN105562097A, CN105562099A, CN105566036A, CN105566045A, CN105566037A, CN105566046A, CN104415790A, etc. disclose a series of polymerization catalysts with PCCP skeleton structure ligands. The polymerization activity of PCCP ligands is similar to that of Sasol's PNP ligands, but there are more isoolefins in the product, which is difficult to separate, and the generation of more by-product polymers easily causes pipeline blockage of the production device, which is not conducive to the long-term operation of industrial devices.

[0006] Under the premise of ensuring catalytic activity, the total selectivity of 1-hexene and 1-octene of existing catalytic systems such as PNP and PCCP is only about 80%, which still has a lot of room for improvement. At the same time, when these catalytic systems are used to prepare α-olefins, the content of by-product polymers is generally high, which seriously affects the long-term operation of industrial equipment. In view of the low selectivity and high amount of by-product polymers produced by existing ligand-structured catalysts, it is urgent to develop catalysts with new ligand skeleton structures. Summary of the invention

[0007] In view of the above problems existing in the prior art, the present invention has developed a PCNSiP ligand for the first time, which, together with a transition metal compound and a co-catalyst, forms an in-situ catalytic system to achieve high-activity and high-selectivity catalytic polymerization of ethylene to prepare 1-hexene and 1-octene.

[0008] In a first aspect of the present invention, a PCNSiP ligand is provided, wherein the structural formula of the ligand is shown in Formula I:

[0009]

[0010] Among them, C m is selected from alkylene, substituted alkylene, arylene, substituted arylene, m represents the number of bridging carbon atoms, m is 1 to 20; R 1 , R 2 , R 3 , R 4 R is independently selected from a linear alkyl group, a branched alkyl group, a cycloalkyl group, a substituted cycloalkyl group, an aryl group, and a substituted aryl group; 5 , R 6 Each is independently selected from alkyl, substituted alkyl, cycloalkyl, substituted cycloalkyl, aryl, and substituted aryl.

[0011] In some embodiments of the first aspect of the present invention, C in Formula I m is selected from –CH2–CH2–, –CH(CH3)–CH2–, –CH(CH3)–CH(CH3)–, –CH(Ph)–CH2–, –CH(Ph)–CH(Ph)–, –C6H4–, –C6H4–CH2–, –CH2–CH2–CH2–, –CH(CH3)–CH2–CH2–, –CH(Ph)–CH2–CH2–, –CH(Ph)–CH(Ph)–CH2–. In some preferred embodiments, C m Selected from CH2–CH2–, –C6H4–, –C6H4–CH2–, –CH2–CH2–CH2–.

[0012] In some embodiments of the first aspect of the present invention, R in Formula I 1 , R 2 , R 3 , R 4 are independently selected from methyl, ethyl, isopropyl, n-butyl, isobutyl, tert-butyl, cyclohexyl, phenyl, 2-methylphenyl, 3-methylphenyl, 4-methylphenyl, 2,6-dimethylphenyl, 2,6-diethylphenyl, 2,6-diisopropylphenyl, 2,4,6-trimethylphenyl, 2-methoxyphenyl, 4-methoxyphenyl, 2,6-dimethoxyphenyl, 2,6-diethoxyphenyl, 2,4,6-trimethoxyphenyl, naphthyl, biphenyl. In some preferred embodiments, R 1 , R 2 , R 3 , R 4 Each is independently selected from methyl, ethyl, isopropyl, n-butyl, tert-butyl, cyclohexyl, phenyl and naphthyl.

[0013] In some embodiments of the first aspect of the present invention, R in Formula I 5 , R 6 are independently selected from methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, neopentyl, cyclobutyl, cyclopentyl, cyclohexyl, 2-methylcyclohexyl, 2,6-dimethylcyclohexyl, adamantyl, phenyl, naphthyl, biphenyl. In some preferred embodiments, R 5 , R 6 Each is independently selected from methyl, ethyl, isopropyl, n-butyl, isobutyl, tert-butyl, cyclopentyl, cyclohexyl, phenyl and naphthyl.

[0014] In some embodiments of the first aspect of the present invention, the PCNSiP ligand has one of the following structural formulas:

[0015] In a second aspect of the present invention, a method for preparing a PCNSiP ligand according to the first aspect of the present invention is provided, the method comprising the following steps:

[0016] Step a, synthesizing a phosphine-substituted monochlorosilane intermediate by reaction according to the following reaction formula (a):

[0017] Reaction (a)

[0018] Step b, synthesizing the ligand by reacting according to the following reaction formula (b):

[0019] Reaction (b)

[0020] Among them, C m is selected from alkylene, substituted alkylene, arylene, substituted arylene, m represents the number of bridging carbon atoms, m is 1 to 20; R 1 , R 2 , R 3 , R 4 R is independently selected from a linear alkyl group, a branched alkyl group, a cycloalkyl group, a substituted cycloalkyl group, an aryl group, and a substituted aryl group; 5 , R 6 Each is independently selected from alkyl, substituted alkyl, cycloalkyl, substituted cycloalkyl, aryl, and substituted aryl.

[0021] In some embodiments of the second aspect of the present invention, in step a, at low temperature (e.g., -80°C to -10°C), n BuLi was slowly added dropwise to the disubstituted phosphine hydrogen (R 3 R 4 After the addition is complete, the temperature is raised to room temperature for a sufficient time (e.g., more than 2 hours) to generate lithium salt (R 3 R 4 PLi), after filtration, R3R4PLi is redissolved in n-hexane to form a suspension, and disubstituted dichlorosilane (R 5 R 6 SiCl2), filter out the insoluble LiCl, collect the filtrate, and remove the solvent to obtain the phosphine-substituted monochlorosilane intermediate [R 5 R 6 Si(R 3 R 4 P)Cl].

[0022] In some embodiments of the second aspect of the present invention, in step b, the phosphine amine intermediate (R 1 R 2 PC mNH2) was dissolved in tetrahydrofuran, and 1.2 equivalents of Et3N were added. The above solution was cooled to -10~0 ℃, and R 5 R 6 Si(R 3 R 4 The tetrahydrofuran solution of P)Cl is gradually restored to room temperature to allow the reaction to fully occur. The reaction product is filtered and the volatile substances are removed under reduced pressure to obtain the PCNSiP ligand of the present invention.

[0023] In a third aspect of the present invention, a catalytic system is provided. The catalytic system comprises: a PCNSiP ligand according to the first aspect of the present invention, a transition metal compound and a co-catalyst.

[0024] In some embodiments of the third aspect of the present invention, the transition metal compound includes one or more of the following substances: chromium trichloride, chromium trichloride tetrahydrofuran complex, chromium dichloride, chromium dichloride tetrahydrofuran complex, chromium dichloride toluene tetrahydrofuran complex, chromium dichloride carbon carbene complex, chromium trichloride carbon carbene complex, chromium acetylacetonate, chromium tri(2-ethylhexanoate), methyl chromium dichloride tetrahydrofuran complex, triphenyl chromium tetrahydrofuran complex, dimethyl chromium carbon carbene complex, diethyl chromium carbon carbene complex, diphenyl chromium carbon carbene complex, carbonyl chromium, nickel chloride and alkyl nickel. Among them, in some preferred embodiments, the transition metal compound includes one or more of the following substances: chromium trichloride tetrahydrofuran complex, chromium acetylacetonate, chromium tri(2-ethylhexanoate), nickel chloride.

[0025] In some embodiments of the third aspect of the present invention, the co-catalyst comprises an alkyl aluminum co-catalyst or an organic boron co-catalyst.

[0026] In some embodiments of the third aspect of the present invention, the alkylaluminum co-catalyst comprises one or more of the following substances: trimethylaluminum, triethylaluminum, triisobutylaluminum, tri-n-butylaluminum, tri-n-hexylaluminum, tri-n-octylaluminum, methylaluminoxane (MAO), modified methylaluminoxane (MMAO, such as triisobutylaluminum modified), ethylaluminoxane, isobutylaluminoxane, diethylaluminum chloride, ethylaluminum dichloride and tris(pentafluorophenyl)aluminum.

[0027] In some embodiments of the third aspect of the present invention, the organic boron co-catalyst includes one or more of the following substances: tris(pentafluorophenyl)boron, tetrafluoroborate, tetrakis(pentafluorophenyl)borate, tris(perfluoroaryl)borane and tetrakis(perfluoroaryl)borate.

[0028] In the fourth aspect of the present invention, there is provided use of the catalytic system described in the third aspect of the present invention in the preparation of α-olefins by polymerization of ethylene.

[0029] In some embodiments of the fourth aspect of the present invention, the α-olefin comprises 1-hexene or 1-octene.

[0030] In the fifth aspect of the present invention, a method for preparing α-olefins by ethylene polymerization is provided, the method comprising: using the PCNSiP ligand described in the first aspect of the present invention in the ethylene polymerization reaction, the ligand and the transition metal compound and the co-catalyst form a catalytic system in situ.

[0031] In some embodiments of the fifth aspect of the present invention, the method comprises the following steps: under an ethylene atmosphere, adding the PCNSiP ligand, transition metal compound and co-catalyst in the catalytic system to an organic solvent, and sequentially introducing hydrogen and ethylene to carry out a polymerization reaction, wherein the polymerization reaction temperature is 10~150°C, the reaction pressure is 0.1~15MPa, and the reaction time can last 0.1~48 h.

[0032] In some embodiments of the fifth aspect of the present invention, the molar concentration of the ligand is 0.005-1 mmol / L, the molar concentration of the transition metal compound is 0.005-1 mmol / L, and the molar concentration of the co-catalyst is 0.1-1000 mmol / L.

[0033] In some embodiments of the fifth aspect of the present invention, the organic solvent is selected from one of the following solvents: toluene, xylene, mesitylene, pentane, cyclopentane, methylcyclopentane, hexane, cyclohexane, methylcyclohexane, heptane, octane, nonane, decane, carbon undecane, carbon dodecane, carbon tridecane, carbon tetradecane, carbon pentadecane, carbon hexadecane, 1-hexene, 1-octene, 1-decene, dichloromethane, dichloroethane, chlorobenzene, o-dichlorobenzene, m-dichlorobenzene, p-dichlorobenzene, bromobenzene, o-dibromobenzene, m-dibromobenzene and p-dibromobenzene.

[0034] Compared with the prior art, the present invention has the following beneficial technical effects:

[0035] The present invention develops a PCNSiP ligand for the first time, and uses the ligand as an ethylene polymerization catalytic ligand to form an in-situ catalytic system with a transition metal compound and a co-catalyst, without the need for a pre-reaction to form an organic metal complex.

[0036] When the catalytic system comprising the PCNSiP ligand of the present invention is used for the polymerization of ethylene to prepare α-olefins, the catalytic activity is high. In an exemplary embodiment of the present invention, the catalytic activity is as high as 5×10 7 ~12×10 7 g / (mol Cr·h); and the catalyst has good stability. After 120 minutes of continuous reaction, its catalytic activity remains basically unchanged.

[0037] When the catalytic system of the present invention is used for ethylene polymerization reaction, 1-hexene and 1-octene can be produced with high selectivity. In an exemplary embodiment of the present invention, the selectivity of 1-hexene and 1-octene exceeds 90%, and the ratio of 1-octene to 1-hexene can reach 5:1.

[0038] When the catalytic system of the present invention is used to carry out ethylene polymerization to prepare 1-hexene and 1-octene, the amount of by-product polymer generated is as low as 0.05wt%, which can effectively avoid the blockage of the production device pipeline and is conducive to the long-term operation of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 The nuclear magnetic resonance of the PCNSiP ligand of Example 3 of the present invention 31 P spectrum.

[0040] Figure 2 This is a gas chromatographic analysis chart of the ethylene oligomerization product of Example 2 of the present invention (the internal standard is n-heptane). DETAILED DESCRIPTION

[0041] Various aspects of the present invention will be described in detail below in conjunction with specific embodiments. These specific embodiments are only used to illustrate the present invention and do not limit the protection scope and essential content of the present invention.

[0042] Example 1

[0043] 1. Preparation of PCNSiP ligands for ethylene oligomerization catalysis:

[0044] The preparation of the PCNSiP ligand of this embodiment includes the following steps:

[0045] (1) Step a: Synthesize the intermediate according to the following synthetic route:

[0046]

[0047] Specifically, at -10 °C, n BuLi (22 mL, 2.4M in hexane, 52 mmol) was slowly added dropwise to a n-hexane solution of Ph2PH (8.7 mL, 50 mmol). After the addition was completed, the temperature was raised to room temperature for more than 2 hours to fully react and generate a lithium salt (Ph2PLi), which was filtered out. Weigh 9.6 g (50 mmol), dissolve Ph2PLi in n-hexane to form a suspension, slowly add Me2SiCl2 (6.0 mL, 50 mmol) dropwise at -10 °C, filter out LiCl, collect the filtrate, and remove the solvent to obtain the Me2Si(Ph2P)Cl intermediate. Weigh 12.4 g, with a yield of 89%.

[0048] The NMR data of the intermediate are as follows: 31 P NMR (162 MHz, C6D6): -55.69.

[0049] (2) Step b: Using the intermediate synthesized in step a, the PCNSiP ligand of formula II is synthesized according to the following synthetic route:

[0050] Specifically, Ph2PCH2CH2NH2 (2.3 g, 10 mmol) light yellow viscous liquid was dissolved in tetrahydrofuran, and 1.2 equivalents of Et3N were added. The above solution was cooled to 0 °C in an ice-water bath, and a tetrahydrofuran solution of Me2Si(Ph2P)Cl (2.8 g, 10 mmol) was slowly added dropwise, gradually restored to room temperature, and the reaction was continued for 5 h. Filtered, volatile substances were removed under reduced pressure, and a white solid was obtained, which was the target PCNSiP ligand shown in Formula II. Weighing 4.0 g, the yield was 85%.

[0051] The NMR data of the ligand are as follows: 31 P NMR (162 MHz, C6D6): -21.98 (d, J = 40.5 Hz), -40.72.

[0052] 2. A catalytic system comprising a PCNSiP ligand of formula II is used for the oligomerization of ethylene to prepare 1-hexene and 1-octene:

[0053] The 1L high-pressure reactor was installed and debugged, preheated to 120 °C, vacuum dried for 5 h, replaced with nitrogen three times, and then cooled to room temperature. 200 mL of dry methylcyclohexane solution, 0.58 g of MMAO-3A (7wt% Al, methylcyclohexane solution, co-catalyst), 1.41 mg of the ligand shown in the above formula II and 1.05 mg of chromium acetylacetonate (transition metal compound) were added in sequence, and quickly heated to 45 °C. At the same time, hydrogen was introduced to 0.5 MPa, ethylene was introduced to 4.5 MPa, the stirring rate was 500 rpm, and the mixture was maintained for 60 min to carry out ethylene polymerization.

[0054] After the reaction was completed, the ethylene was stopped, the reaction system was quickly cooled to 5 °C, the pressure was slowly released, 5 mL of isooctyl alcohol was added for quenching, the mixture was shaken, allowed to stand, 2 g of n-heptane as an internal standard was added, and the dried organic phase was analyzed by gas chromatography.

[0055] The catalyst activity was calculated by internal standard method to be 8.2×10 7 g / (mol Cr·h). The specific composition of the ethylene polymerization product is recorded in Table 1.

[0056] Example 2

[0057] Example 2 relates to a PCNSiP ligand shown in the following formula III, which is synthesized using a method similar to that of Example 1, except that Ph2PCH2CH2NH2 in Example 1 is replaced by Ph2PCH2CH2CH2NH2 to obtain the PCNSiP ligand shown in formula III.

[0058] The ligand was subjected to NMR 31 P analysis, the obtained NMR data are as follows: 31 P NMR (162 MHz, C6D6): -16.56, -40.74.

[0059]

[0060] The catalytic system of Example 2 is different from that of Example 1 in that: Example 2 uses 1.46 mg of the ligand shown in Formula III to form a catalytic system with chromium acetylacetonate (transition metal compound) and MMAO-3A (cocatalyst), and other conditions are the same as those of Example 1. The catalytic system is applied to ethylene oligomerization reaction, and the catalyst activity is calculated by the internal standard method to be 12.3×10 7 g / (mol Cr·h), the specific composition of the product is recorded in Table 1, and the gas chromatographic analysis of the product is shown in Figure 2 shown.

[0061] Example 3

[0062] Example 3 relates to a PCNSiP ligand shown in the following formula IV. In the preparation method of the ligand, the preparation of the Me2Si(Ph2P)Cl intermediate is the same as that in Example 1. However, in step b, the synthetic route is as follows:

[0063]

[0064] Specifically, 2-Ph2PC6H4NH2 (2.8 g, 10 mmol) solid was dissolved in tetrahydrofuran, and 1.2 equivalents of Et3N were added. The above solution was placed in a refrigerator for 1 h, cooled to -10 °C, and a tetrahydrofuran solution of Me2Si(Ph2P)Cl (2.8 g, 10 mmol) was slowly added dropwise, gradually restored to room temperature, and the reaction was continued for 5 h. Filtered, volatile substances were removed under reduced pressure, and a white solid was obtained, which was the target ligand shown in Formula IV, weighing 4.2 g, with a yield of 81%.

[0065] The ligand was subjected to NMR 31 P analysis, NMR 31 P spectrum Figure 1As shown, the NMR data are as follows: 31 P NMR (162MHz, C6D6): -22.91, -40.72.

[0066]

[0067] The catalytic system of Example 3 is different from that of Example 1 in that 1.56 mg of the ligand of Formula IV is used to form a catalytic system with chromium acetylacetonate (transition metal compound) and MMAO-3A (cocatalyst), and other conditions are the same as those of Example 1. The catalytic system is applied to ethylene oligomerization reaction, and the catalyst activity is calculated by the internal standard method to be 11.8×10 7 g / (molCr·h), the specific composition of the product is recorded in Table 1.

[0068] Example 4

[0069] The difference between Example 4 and Example 3 is that in the catalytic system, the addition amount of the co-catalyst MMAO-3A (7wt% Al, n-heptane solution) is reduced to 0.46 g, and the other conditions are the same as those in Example 3.

[0070] The catalyst activity was calculated by internal standard method to be 9.6×10 7 g / (mol Cr·h), and the specific composition of the product is recorded in Table 1.

[0071] Example 5

[0072] The difference between Example 5 and Example 3 is that in the catalytic system, the addition amount of the co-catalyst MMAO-3A (7wt% Al, n-heptane solution) is reduced to 0.35 g, and the other conditions are the same as those in Example 3.

[0073] The catalyst activity was calculated by internal standard method to be 7.5×10 7 g / (mol Cr·h), and the specific composition of the product is recorded in Table 1.

[0074] Example 6

[0075] The difference between Example 6 and Example 3 is that in the catalytic system, the amount of the co-catalyst MMAO-3A (7wt% Al, n-heptane solution) added is reduced to 0.29 g, and 1.7 mg of tris(pentafluorophenyl)boron (organic boron co-catalyst) is added, and the other conditions are the same as in Example 3.

[0076] The catalyst activity was calculated by internal standard method to be 9.2×10 7 g / (mol Cr·h), and the specific composition of the product is recorded in Table 1.

[0077] Example 7

[0078] Example 7 relates to a PCNSiP ligand shown in the following formula V, which is synthesized by a method similar to that of Example 1, except that Me2SiCl2 in Example 1 is replaced by i Pr2SiCl2, replace Ph2PCH2CH2NH2 in Example 1 with Cy2PCH2CH2CH2NH2.

[0079] The ligand synthesized in Example 7 was subjected to NMR 31 P analysis, the obtained NMR data are as follows: 31 P NMR (162MHz, C6D6): -16.59, -40.75.

[0080]

[0081] The catalytic system of Example 7 is different from that of Example 1 in that: Example 7 uses 1.66 mg of the ligand represented by formula V, chromium acetylacetonate (transition metal compound), and MMAO-3A (cocatalyst) to form a catalytic system, and other conditions are the same as those of Example 1. The catalytic system is applied to ethylene polymerization reaction, and the catalyst activity calculated by the internal standard method is 6.4×10 7 g / (mol Cr·h), and the specific composition of the product is recorded in Table 1.

[0082] Example 8

[0083] Example 8 relates to a PCNSiP ligand represented by the following formula VI, which is synthesized by a method similar to that of Example 1, except that Me2SiCl2 in Example 1 is replaced by MeSi(Ph)Cl2.

[0084] The ligand synthesized in Example 8 was subjected to NMR 31 P analysis, the obtained NMR data are as follows: 31 P NMR (162MHz, C6D6): -21.96, -40.73.

[0085]

[0086] The catalytic system of Example 8 is different from that of Example 1 in that 1.60 mg of the ligand represented by Formula VI is used to form a catalytic system with chromium acetylacetonate (transition metal compound) and MMAO-3A (cocatalyst), and other conditions are the same as those of Example 1. The catalytic system is applied to ethylene oligomerization reaction, and the catalyst activity is calculated by the internal standard method to be 5.9×10 7 g / (molCr·h), the specific composition of the product is recorded in Table 1.

[0087] Example 9

[0088] Example 9 relates to a PCNSiP ligand shown in the following formula VII, which is synthesized using a method similar to that of Example 1, except that Me2SiCl2 in Example 1 is replaced by Cy2SiCl2, and Ph2PCH2CH2NH2 in Example 1 is replaced by Ph2PCH2CH2CH2NH2.

[0089] The ligand synthesized in Example 9 was subjected to NMR 31 P analysis, the obtained NMR data are as follows: 31 P NMR (162MHz, C6D6): -16.52, -40.79.

[0090]

[0091] The catalytic system of Example 9 is different from that of Example 1 in that 1.87 mg of the ligand represented by formula VII is used to form a catalytic system with chromium acetylacetonate (transition metal compound) and MMAO-3A (cocatalyst), and other conditions are the same as those of Example 1. The catalytic system is applied to ethylene oligomerization reaction, and the catalyst activity is calculated by the internal standard method to be 8.5×10 7 g / (molCr·h), the specific composition of the product is recorded in Table 1.

[0092] Example 10

[0093] The difference between Example 10 and Example 9 is that the ethylene polymerization reaction time is extended from 60 min to 120 min, and the other conditions are the same as Example 9.

[0094] The catalyst activity was calculated by internal standard method to be 8.1×10 7 g / (mol Cr·h), and the specific composition of the product is recorded in Table 1.

[0095] Embodiment 11

[0096] Example 11 relates to a PCNSiP ligand represented by the following formula VIII, which is synthesized by a method similar to that of Example 1, except that Ph2PH in Example 1 is replaced by t Bu2PH.

[0097] The ligand synthesized in Example 11 was subjected to NMR 31 P analysis, the obtained NMR data are as follows: 31 P NMR (162MHz, C6D6): 3.76, -21.98.

[0098]

[0099] The catalyst system of Example 11 is different from that of Example 1 in that 1.29 mg of the ligand represented by formula VIII is used to form a catalyst system with chromium acetylacetonate (transition metal compound) and MMAO-3A (cocatalyst), and other conditions are the same as those of Example 1. The catalyst system is applied to ethylene oligomerization reaction, and the catalyst activity is calculated by the internal standard method to be 10.4×10 7 g / (molCr·h), the specific composition of the product is recorded in Table 1.

[0100] Example 12

[0101] Example 12 relates to a PCNSiP ligand shown in the following formula IX, which is synthesized by a method similar to that of Example 3, except that 2-Ph2PC6H4NH2 in Example 3 is replaced by t Bu2PCH2CH2NH2.

[0102] The ligand synthesized in Example 12 was subjected to NMR 31 P analysis, the obtained NMR data are as follows: 31 P NMR (162MHz, C6D6): -40.78, 23.26.

[0103]

[0104] The catalyst system of Example 12 is different from that of Example 1 in that 1.29 mg of the ligand of Formula IX is used to form a catalyst system with chromium acetylacetonate (transition metal compound) and MMAO-3A (cocatalyst), and other conditions are the same as those of Example 1. The catalyst system is applied to ethylene oligomerization reaction, and the catalyst activity is calculated by the internal standard method to be 8.6×10 7 g / (molCr·h), the specific composition of the product is recorded in Table 1.

[0105] Table 1: Catalytic reaction results in Examples 1 to 12

[0106]

[0107] As shown in Table 1, the in-situ catalytic system composed of the PCNSiP structured ligand, transition metal compound and co-catalyst can catalyze the polymerization of ethylene to prepare 1-hexene and 1-octene with high activity and selectivity, and the catalytic activity is higher than 5×10 7 (mol Cr·h), and the total selectivity of 1-hexene and 1-octene can exceed 90%, and the ratio of 1-octene to 1-hexene can reach 5:1, and the by-product polymer is as low as 0.05wt%.

[0108] It can also be seen from Example 10 that the catalytic system has good stability, and its catalytic activity is still high after 120 minutes of continuous reaction.

[0109] It should be noted that, in this article, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprises a ..." does not exclude the existence of other identical elements in the process, method, article or device including the element.

[0110] The above embodiments are only used to illustrate the technical solutions of the present invention and cannot be used to limit the protection scope of the present invention. Although the present invention is described in detail with reference to the aforementioned embodiments, ordinary technicians in this field should understand that: without departing from the essence and scope of the present invention, the technical solutions recorded in the aforementioned embodiments can still be modified, or some of the technical features therein can be replaced by equivalents; and these modifications or equivalent replacements still fall within the scope covered by the present invention.

Claims

1. PCNSiP ligand, characterized in that The structural formula of the ligand is shown in Formula I: Among them, C m is –CH2–CH2–, –C6H4–, –C6H4–CH2– or –CH2–CH2–CH2–; R 1 , R 2 , R 3 , R 4 Each of the following is independently selected from methyl, ethyl, isopropyl, n-butyl, isobutyl, tert-butyl, cyclohexyl, phenyl, 2-methylphenyl, 3-methylphenyl, 4-methylphenyl, 2,6-dimethylphenyl, 2,6-diethylphenyl, 2,6-diisopropylphenyl, 2,4,6-trimethylphenyl, 2-methoxyphenyl, 4-methoxyphenyl, 2,6-dimethoxyphenyl, 2,6-diethoxyphenyl, 2,4,6-trimethoxyphenyl, naphthyl, and biphenyl; R 5 , R 6 Each is independently selected from the group consisting of: methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, neopentyl, cyclobutyl, cyclopentyl, cyclohexyl, 2-methylcyclohexyl, 2,6-dimethylcyclohexyl, adamantyl, phenyl, naphthyl, and biphenyl.

2. The PCNSiP ligand according to claim 1, characterized in that R 1 , R 2 , R 3 , R 4 Each of the following is independently selected from: methyl, ethyl, isopropyl, n-butyl, tert-butyl, cyclohexyl, phenyl, and naphthyl.

3. The PCNSiP ligand according to claim 1, characterized in that R 5 , R 6 Each is independently selected from the group consisting of: methyl, ethyl, isopropyl, n-butyl, isobutyl, tert-butyl, cyclopentyl, cyclohexyl, phenyl and naphthyl.

4. The PCNSiP ligand according to claim 1, characterized in that The ligand has one of the following structural formulas: 。 5. A method for preparing the PCNSiP ligand according to any one of claims 1 to 4, characterized in that: The method comprises the following steps: Step a, synthesizing a phosphine-substituted monochlorosilane intermediate by reaction according to the following reaction formula (a): Reaction (a) Step b, synthesizing the ligand by reacting according to the following reaction formula (b): Reaction (b) Among them, C m is selected from –CH2–CH2–, –C6H4–, –C6H4–CH2–, –CH2–CH2–CH2–; R 1 , R 2 , R 3 , R 4 Each of the following is independently selected from methyl, ethyl, isopropyl, n-butyl, isobutyl, tert-butyl, cyclohexyl, phenyl, 2-methylphenyl, 3-methylphenyl, 4-methylphenyl, 2,6-dimethylphenyl, 2,6-diethylphenyl, 2,6-diisopropylphenyl, 2,4,6-trimethylphenyl, 2-methoxyphenyl, 4-methoxyphenyl, 2,6-dimethoxyphenyl, 2,6-diethoxyphenyl, 2,4,6-trimethoxyphenyl, naphthyl, and biphenyl; R 5 , R 6 Each is independently selected from the group consisting of: methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, neopentyl, cyclobutyl, cyclopentyl, cyclohexyl, 2-methylcyclohexyl, 2,6-dimethylcyclohexyl, adamantyl, phenyl, naphthyl, and biphenyl.

6. A catalytic system, characterized in that: The catalytic system comprises: the PCNSiP ligand according to any one of claims 1 to 4, a transition metal compound and a co-catalyst.

7. The catalytic system according to claim 6, characterized in that The transition metal compound includes one or more of the following substances: chromium trichloride, chromium trichloride tetrahydrofuran complex, chromium dichloride, chromium dichloride tetrahydrofuran complex, chromium dichloride toluene tetrahydrofuran complex, chromium dichloride carbon carbene complex, chromium trichloride carbon carbene complex, chromium acetylacetonate, chromium tri(2-ethylhexanoate), methyl chromium dichloride tetrahydrofuran complex, triphenyl chromium tetrahydrofuran complex, dimethyl chromium carbon carbene complex, diethyl chromium carbon carbene complex, diphenyl chromium carbon carbene complex, carbonyl chromium, nickel chloride and alkyl nickel.

8. The catalytic system according to claim 6, characterized in that The cocatalyst comprises an alkyl aluminum cocatalyst or an organic boron cocatalyst, wherein: The alkyl aluminum cocatalyst includes one or more of the following materials: trimethyl aluminum, triethyl aluminum, triisobutyl aluminum, tri-n-butyl aluminum, tri-n-hexyl aluminum, tri-n-octylaluminum, methylaluminoxane MAO, modified methylaluminoxane MMAO, ethylaluminoxane, isobutylaluminoxane, diethylaluminum chloride, ethylaluminum dichloride and tris(pentafluorophenyl)aluminum; The organic boron co-catalyst includes one or more of the following substances: tris(pentafluorophenyl)boron, tetrafluoroborate, tetrakis(pentafluorophenyl)borate.

9. Use of the catalytic system according to any one of claims 6 to 8 in the preparation of α-olefins by the polymerization of ethylene.

10. The use according to claim 9, wherein the α-olefin comprises 1-hexene or 1-octene.

11. A method for preparing α-olefins by ethylene oligomerization, characterized in that: The method comprises the following steps: The PCNSiP ligand as claimed in any one of claims 1 to 4 is used in the ethylene polymerization reaction, wherein the ligand, the transition metal compound and the co-catalyst form an in-situ catalytic system.

12. The method according to claim 11, characterized in that The method comprises the following steps: In an ethylene atmosphere, the PCNSiP ligand, transition metal compound and co-catalyst are added to an organic solvent, and hydrogen and ethylene are introduced in sequence to carry out a polymerization reaction, wherein the polymerization reaction temperature is 10-150° C. and the reaction pressure is 0.1-15 MPa.

13. The method according to claim 12, characterized in that The molar concentration of the ligand is 0.005-1 mmol / L, the molar concentration of the transition metal compound is 0.005-1 mmol / L, and the molar concentration of the co-catalyst is 0.1-1000 mmol / L.

14. The method according to claim 12 or 13, characterized in that The organic solvent is selected from one of the following solvents: toluene, xylene, mesitylene, pentane, cyclopentane, methylcyclopentane, hexane, cyclohexane, methylcyclohexane, heptane, octane, nonane, decane, carbon undecane, carbon dodecane, carbon tridecane, carbon tetradecane, carbon pentadecane, carbon hexadecane, 1-hexene, 1-octene, 1-decene, dichloromethane, dichloroethane, chlorobenzene, o-dichlorobenzene, m-dichlorobenzene, p-dichlorobenzene, bromobenzene, o-dibromobenzene, m-dibromobenzene and p-dibromobenzene.

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