Preparation of quinoline-imine nickel metal catalyst and its application in ethylene oligomerization

Abstract

The present application relates to a kind of quinoline-imino nickel metal catalyst and its preparation method and catalytic application in the selective oligomerization of ethylene, belong to olefin catalytic conversion technical field.The present application is by regulating the type of substituent on aniline ring and quinoline ring, constructs different electronic effect and space steric hindrance catalytic active center, and shows medium to excellent catalytic activity to the selective dimerization of ethylene, and has good thermal stability, target product selectivity is more than 99%.The quinoline-imino nickel metal catalyst prepared in the present application has simple synthesis process, good air stability, outstanding high-temperature resistance, and has important industrial application value.

Description

Technical Field

[0001] This invention relates to the preparation of nitrogen donor nickel metal catalysts and their application in olefin oligomerization reactions. Background Technology

[0002] Linear alpha-olefins (LAOs) are key comonomers in the production of polyethylene, plasticizers, and detergents, possessing extremely high industrial value. Among them, 1-butene has an annual production capacity of 18 million tons, with approximately one-quarter used in chemical and polymer preparation, indicating strong market demand. Currently, the LAOs market exhibits structural differences: the annual scale of C4-C10 short-chain LAOs is approximately 2.5 million tons, with a significantly higher growth rate than C12+ long-chain LAOs. This has driven ethylene oligomerization technology to become a research hotspot, making the development of efficient and stable oligomerization catalysts particularly crucial. Among these, nitrogen-donor nickel catalysts can circumvent the hydride competition interference of early metal systems, demonstrating significant advantages in olefin polymerization (J. Am. Chem. Soc. 1995, 117, 1137-1138).

[0003] This type of nickel catalyst was initially used for ethylene copolymerization (Catal. Sci. Technol. 2013, 3, 1172-1179). In 1987, Klabunde and Itten demonstrated that Shell's advanced olefins process (SHOP) nickel catalyst possessed the potential for ethylene polymerization, and that linear / branched polyethylene could be generated by controlling ligands and conditions (J. Organomet. Chem. 1987, 334, 141-156). Subsequently, it was used for the copolymerization of olefins with polar monomers to prepare functionalized polyolefins, and in recent years its application in the field of ethylene oligomerization has attracted much attention (New J. Chem. 2002, 26, 1474-1478).

[0004] Existing nickel oligomerization catalysts focus on ligand modulation, and tridentate ligands such as PO, NO, PN, NN, NNO, NPN, and NNN have been developed to achieve selective dimerization of ethylene, exhibiting excellent activity for α-olefin preparation. In recent years, imine ligand transition metal complexes have attracted extensive research due to their high polymerization activity, with ligands such as bis(arylimine)pyridine, α-diimine, and phenoxyimine being successively developed. In 2000, Helmut and Alexander synthesized substituted aminoquinoline nickel complexes, laying the foundation for the design of quinoline nickel catalysts.

[0005] In this invention, a series of quinoline-imine ligands with different substituents were designed and synthesized, and then reacted with nickel bromide to obtain a novel quinoline-imine-based nickel metal catalyst. This synthetic route is simple to operate and uses readily available raw materials. The weak coordination of the nickel center was achieved by introducing halogen (Br, Cl) substituents, resulting in a Ni(II) complex with a distorted trigonal bipyramidal configuration. When the obtained nickel complex was used in the oligomerization reaction of ethylene, it was found that in the presence of the co-catalyst AlEtCl2, the catalyst exhibited moderate to high catalytic activity for the selective oligomerization of ethylene, and the catalytic performance was closely related to the complex structure and reaction conditions. The nickel catalyst reported in this invention has excellent high-temperature resistance; the catalytic activity reaches its maximum value (3.46 × 10⁻⁶) when the reaction temperature reaches 90 °C. 5 g·mol -1 (Ni)・h -1 This invention provides a novel high-temperature resistant nickel-based ethylene oligomerization catalyst, offering a new technical approach for the efficient preparation of linear α-olefins. Summary of the Invention

[0006] The purpose of this invention is to provide a method for preparing a quinoline-imine-based nickel metal catalyst and its application in olefin oligomerization reactions.

[0007] This invention provides a quinoline-imine-based nickel metal catalyst of formula (I):

[0008]

[0009] Wherein, X is selected from bromine and chlorine; R 1 Selected from hydrogen, isopropyl, chlorine, fluorine; R 2 Selected from methyl, chlorine, isopropyl, and diphenylmethyl.

[0010] Preferably, the quinoline-imine-based nickel metal catalyst of the present invention is selected from any of the following structures: C1: L1NiBr2, where L1 = 2-[2,6-diisopropylphenyl]iminomethyl-8-bromoquinoline; C2: L2NiBr2, where L2 = 2-[2,6-dimethylphenyl]iminomethyl-8-bromoquinoline; C3: L3NiBr2, where L3 = 2-[2,6-dichlorophenyl]iminomethyl-8-bromoquinoline; C4: L4NiBr2, where L4 = 2-[2,6-bis(diphenylmethyl)-4-isopropylphenyl]iminomethyl-8-bromoquinoline; C5: L5NiBr2, where L5 = 2-[2,6-diisopropylphenyl]iminomethyl-8-chloroquinoline.

[0011] Under a nitrogen atmosphere, the nickel precursor [NiBr2(DME)] was dissolved in 20-80 mL of anhydrous solvent, and 1.0-1.1 molar equivalents of quinoline imine ligand were added. The reaction was carried out at room temperature for 12 hours under nitrogen protection. After the reaction was completed, the solvent was removed under reduced pressure, and the catalyst was washed with diethyl ether to obtain the quinoline-imine-based nickel metal catalyst.

[0012] In the above preparation method, the anhydrous solvent is selected from diethyl ether, toluene, n-hexane, xylene, and benzene.

[0013] This invention also provides the application of the above-mentioned quinoline-imine nickel metal catalyst in the catalytic oligomerization of olefins.

[0014] In the above applications, the olefin monomer is ethylene.

[0015] In the above applications, the quinoline-imine nickel metal catalyst needs to be used in conjunction with a co-catalyst, which is one or more of ethyl aluminum chloride, diethyl aluminum chloride, methylaluminoxane, and trimethylaluminum.

[0016] In the above applications, the reaction temperature is 30-90 ℃, the reaction pressure is 0.1-0.5 MPa, and the reaction solvent is one or more of toluene, n-hexane, and heptane.

[0017] This invention provides the preparation of a quinoline-imine-based nickel metal catalyst and its application in the selective oligomerization of ethylene. The quinoline-imine-based nickel metal catalyst reported in this invention features simple synthesis, readily available raw materials, high product yield, and excellent catalytic activity (up to 3.46 × 10⁻⁶). 5 g·mol -1 (Ni)・h -1 This invention possesses advantages such as high selectivity for 1-butene (>99%) and good high-temperature resistance (maintaining high activity even at 90 °C), making it particularly suitable for the efficient preparation of short-chain linear α-olefins such as 1-butene under industrial conditions. The metal catalyst provided by this invention is original and innovative, and can promote the development of my country's high-end polyolefin and fine chemical industries. Attached Figure Description

[0018] Figure 1 The 1H NMR spectrum of complex L1; Figure 2 This is the crystal structure diagram of coordination compound C2; Figure 3 This is the crystal structure diagram of coordination compound C5. Detailed Implementation

[0019] The present invention is further illustrated by examples, but is not limited thereto. These examples will enable those skilled in the art to gain a more comprehensive understanding of the invention.

[0020] Unless otherwise specified, the experimental methods used in the following examples are conventional methods.

[0021] Unless otherwise specified, all raw materials and reagents described below are commercially available finished products.

[0022] In this invention, the ligand precursor 8-bromo(chloro)-2-quinoline carbaldehyde was synthesized according to the methods described in the literature (Organometallics 2008, 27, 88-99; Coord. Chem. Rev. 2018, 363, 92-108). The ligands in this invention are as shown in formula (II), wherein L1 and L5 are prepared by a simple amine-aldehyde condensation reaction under acidic conditions; ligands L2–L4 are prepared by first reacting substituted aniline with trimethylaluminum to generate aminoaluminane, followed by an amine-aldehyde condensation reaction.

[0023]

[0024]

[0025] The present invention is described below with reference to specific embodiments.

[0026] Example 1: Preparation of Catalyst C1 2,6-Diisopropylaniline (1.95 g, 11.0 mmol), 8-bromo-2-quinolinecarbaldehyde (2.36 g, 10.0 mmol), and p-toluenesulfonic acid (30 mg, 0.174 mmol) were weighed and dissolved in 50 mL of ethanol. The mixture was stirred at 90 °C under a nitrogen atmosphere for 12 hours. The mixture was cooled to room temperature, the solvent was removed by rotary evaporation, and the mixture was recrystallized with an appropriate amount of methanol to give a yellow solid L1 (3.88 g, 90% yield). 1H NMR (400 MHz, CDCl3) δ 8.74 (s, 1H), 8.28 (d, J =7.5 Hz, 1H), 7.91-7.85 (m, 2H), 7.80 (dd, J = 8.9, 1.2 Hz, 1H), 7.44 (t, J =8.7 Hz, 1H), 7.26 (dd, J = 8.1, 6.4 Hz, 1H), 7.20 (dd, J = 7.3, 0.9 Hz, 2H), 3.34-3.23 (m, 2H), 1.27 (d, J = 6.3 Hz, 10H). 13C NMR (400 MHz, CDCl3) δ159.09, 153.97, 146.92, 146.01, 138.06, 136.87, 132.89, 129.61, 127.92,126.76, 126.42, 124.59, 121.28, 118.36, 29.40, 22.19 ppm. 22 H 23 BrN2: C, 66.84; H, 5.86; Br, 20.21; N, 7.09. Found: C, 66.82; H, 5.82; Br, 20.20; N, 7.07. Weigh out [NiBr2(DME)] (0.468 g, 1.0 mmol), add 10 mL of anhydrous dichloromethane, add ligand L1 (0.435 g, 1.10 mmol), and stir for 12 hours at room temperature under nitrogen protection. After the reaction is complete, remove the solvent, wash with diethyl ether, and filter to obtain 0.77 g of brownish-yellow solid C1, yield 85%. 1H NMR (400 MHz, C6D6): δ 8.55 (d, J =8.1 Hz, 1H), 8.25 (s, 1H), 8.14 (d, J = 8.0 Hz, 1H), 7.64 (dd, J = 7.0, 1.5Hz, 1H), 7.54 (d, J = 14.7 13C NMR (400 MHz, C6D6): δ 156.54, 142.30, 141.89, 139.36, 137.89,136.98, 133.94, 129.42, 127.31, 126.58, 126.06, 125.10-124.98, 124.45, 29.78,23.62 ppm. Anal. Calcd for C 22 H 23 Br3N2Ni: C, 43.05; H, 3.78; Br, 39.05; N, 4.56. Found: C, 43.02; H, 3.75; Br, 39.03; N, 4.54.

[0027] Example 2: Preparation of catalyst C2 Weigh 1.95 g (11 mmol) of 2,6-diisopropylaniline and react it with 0.793 g (11 mmol) of trimethylaluminum in anhydrous toluene at room temperature for 2 h. Then add 2.24 g (10 mmol) of 8-bromo-2-quinolinecarbaldehyde and stir overnight at room temperature. After removing the solvent using a rotary evaporator, recrystallize with an appropriate amount of ethanol to give a yellow solid L2 (3.77 g, 90% yield). 1 HNMR (400 MHz, CDCl3): δ 8.75 (s, 1H), 8.28 (d, J = 7.3 Hz, 1H), 7.91-7.83 (m,2H), 7.80 (dd, J = 8.9, 1.2 Hz, 1H), 7.44 (t, J = 8.7 Hz, 1H), 7.11 (d, J =7.1 Hz, 1H), 6.87 (d, J = 7.2 Hz, 2H), 2.21 (s, 6H). 13C NMR (400 MHz, CDCl3): δ 160.42, 153.74, 151.45, 146.92, 136.87, 135.89, 135.81, 132.89, 129.61,126.95, 126.92, 126.76, 126.42, 126.16, 121.28, 118.36, 17.90, 17.88 ppm.Anal. Calcd for C 18 H 15 BrN2: C, 63.73; H, 4.46; Br, 23.55; N, 8.26. Found: C, 63.71; H, 4.44; Br, 23.54; N, 8.23. Weigh out [NiBr2(DME)] (0.468 g, 1.0 mmol), add 10 mL of anhydrous dichloromethane, add ligand L2 (0.373 g, 1.10 mmol), and stir for 12 hours at room temperature under nitrogen protection. After the reaction is complete, remove the solvent, wash with diethyl ether, and filter to obtain 0.715 g of brownish-yellow solid C2, yield 85%. 1H NMR (400 MHz, C6D6): δ 8.46 (d, J =7.9 Hz, 1H), 8.14 (d, J = 8.0 Hz, 1H), 7.64 (dd, J = 7.0, 1.5 Hz, 1H), 7.31(dd, J = 7.6, 1.4 Hz, 1H), 7.27 (dd, J = 7.6, 7.0 Hz, 1H), 7.09 (s, 0H), 6.69– 6.64 (m, 2H), 2.14 (s, 6H) ppm. 13C NMR (400 MHz, C6D6): δ 156.82, 156.52,139.36, 136.98, 136.81, 134.78, 133.94, 129.42, 128.75, 126.67, 126.06,125.08, 124.45, 19.98 ppm. Anal. Calcd for C 18 H 15 Br3N2Ni: C, 38.76; H, 2.71; Br, 42.98; N, 5.02. Found: C, 38.75; H, 2.70; Br, 42.97; N, 5.01.

[0028] Example 3: Preparation of catalyst C3 2,6-Dichloroaniline (1.78 g, 11.0 mmol) was weighed and reacted with trimethylaluminum (0.793 g, 11 mmol) in anhydrous toluene at room temperature for 2 h. Then, 8-bromo-2-quinolinecarbaldehyde (2.24 g, 10 mmol) was added, and the mixture was stirred overnight at room temperature. After removing the solvent using a rotary evaporator, the mixture was recrystallized with an appropriate amount of ethanol to give a yellow solid L3 (3.62 g, 90% yield). 1 H NMR(400 MHz, CDCl3): δ 8.92 (s, 1H), 8.28 (d, J = 7.3 Hz, 1H), 7.90 - 7.85 (m,2H), 7.80 (dd, J = 8.9, 1.2 Hz, 1H), 7.47 - 7.41 (m, 3H), 7.33 (dd, J = 8.1,7.1 Hz, 1H). 13 C NMR (400 MHz, CDCl3): δ 159.42, 154.15, 147.92, 146.92,136.87, 132.89, 130.18, 129.97, 129.61, 126.76, 126.37, 121.32, 118.36 ppm.Anal. Calcd for C 16 H9BrCl2N2: C, 50.56; H, 2.39; Br, 21.02; Cl, ​​18.65; N, 7.37.Found: C, 50.54; Weigh out [NiBr2(DME)] (0.468 g, 1.0 mmol), add 10 mL of anhydrous dichloromethane, add ligand L3 (0.431 g, 1.10 mmol), and stir for 12 hours at room temperature under nitrogen protection. After the reaction is complete, remove the solvent, wash with diethyl ether, and filter to obtain 0.782 g of brownish-yellow solid C3, with a yield of 87%. 1 H NMR (400 MHz, C6D6): δ 8.52 (d, J =7.9 Hz, 1H), 8.14 (d, J = 8.0 Hz, 1H), 7.81 (s, 1H), 7.64 (dd, J = 7.0, 1.5Hz, 1H), 7.33 - 7.21 (m, 3H), 7.18 - 7.15 (m, 2H) ppm. 13C NMR (400 MHz, C6D6)δ 156.42, 140.76, 139.78, 139.37, 136.98, 133.94, 131.06, 131.01, 129.67,129.42, 127.61, 126.58, 126.06, 125.08, 124.44 ppm. Anal. Calcd forC 16 H9Br3Cl2N2Ni: C, 32.11; H, 1.52; Br, 40.05; Cl, ​​11.84; N, 4.68. Found: C, 32.10;

[0029] Example 4: Preparation of Catalyst C4 Weigh 5.14 g (11.0 mmol) of 2,6-bis(diphenylmethyl)-4-isopropylaniline and react it with trimethylaluminum (0.793 g, 11 mmol) in anhydrous toluene at room temperature for 2 h. Then add 2.24 g (10 mmol) of 8-bromo-2-quinolinecarbaldehyde and stir overnight at room temperature. After removing the solvent using a rotary evaporator, recrystallize with an appropriate amount of ethanol to give a yellow solid L4 (6.6 g, 90% yield). 1 H NMR (400 MHz, CDCl3): δ 8.76 (s, 1H), 8.28 (d, J = 7.4 Hz,1H), 7.91 - 7.85 (m, 2H), 7.80 (dd, J = 8.9, 1.2 Hz, 1H), 7.44 (t, J = 8.7Hz, 1H), 7.30 (dt, J = 7.2, 2.4 Hz, 9H), 7.27 - 7.20 (m, 4H), 7.18 (s, 2H), 5.65 (p, J = 1.0 Hz, 2H), 3.02 (dt, J = 12.9, 6.4 Hz, 1H), 1.24 (d, J = 6.6Hz, 5H) ppm. 13C NMR (400 MHz, CDCl3): δ 158.91, 153.90, 152.62, 146.92,145.59, 142.63, 142.61, 142.59, 142.56, 137.86, 137.80, 136.87, 132.89,129.61, 129.34, 129.31, 129.28, 129.26, 129.23, 129.21, 129.18, 129.16,128.68, 128.66, 128.64, 128.63, 128.60, 128.59, 128.57, 128.55, 126.94,126.91, 126.88, 126.85, 126.76, 126.42, 124.77, 124.74, 121.28, 118.36,53.01, 52.95, 34.04, 23.77 ppm. Anal. Calcd for C 45 H 37 BrN2: C, 78.82; H, 5.44; Br, 11.65; N, 4.09. Found: C, 78.80; H, 5.42; Br, 11.63; N, 4.06. Weigh out [NiBr2(DME)] (0.468 g, 1.0 mmol), add 10 mL of anhydrous dichloromethane, add ligand L4 (0.754 g, 1.10 mmol), and stir for 12 hours at room temperature under nitrogen protection. After the reaction is complete, remove the solvent, wash with diethyl ether, and filter to obtain 1.11 g of brownish-yellow solid C4, with a yield of 91%. 1 H NMR (400 MHz, C6D6): δ 8.55 (d, J =8.0 Hz, 1H), 8.14 (d, J = 8.0 Hz, 1H), 7.64 (dd, J = 7.0, 1.5 Hz, 1H), 7.55(s, 1H), 7.35 – 7.20 (m, 23H), 6.85 (d, J = 0.7 Hz, 2H), 5.73 (p, J = 1.1 Hz,2H), 3.06 – 2.97 (m, 1H), 1.24 (d, J= 6.6 Hz, 5H) ppm.13C NMR (400 MHz, C6D6)δ 157.03, 156.71, 146.61, 141.83, 141.80, 141.78, 141.75, 140.51, 140.45,139.36, 137.75, 136.98, 133.94, 129.42, 129.34, 129.31, 129.29, 129.26,129.24, 129.21, 129.19, 129.16, 128.68, 128.66, 128.64, 128.63, 128.60,128.59, 128.57, 128.55, 126.94, 126.91, 126.88, 126.85, 126.58, 126.06,125.75, 125.72, 125.08, 124.45, 53.20, 53.14, 34.01, 23.77 ppm. Anal. Calcdfor C 45 H 37 Br3N2Ni: C, 59.78; H, 4.12; Br, 26.51; N, 3.10. Found: C, 59.75; H, 4.09; Br, 26.48; N, 3.07.

[0030] Example 5: Preparation of Catalyst C5 2,6-Diisopropylaniline (1.77 g, 10.0 mmol), 8-chloro-2-quinoline carbaldehyde (1.91 g, 10.0 mmol), and p-toluenesulfonic acid (30 mg, 0.174 mmol) were weighed and dissolved in 50 mL of ethanol. The mixture was stirred at 90 °C under a nitrogen atmosphere for 12 hours. The mixture was cooled to room temperature, the solvent was removed by rotary evaporation, and the mixture was recrystallized with an appropriate amount of methanol to give a yellow solid L5 (3.88 g, 90% yield). 1 H NMR (400 MHz, CDCl3) δ 8.74 (s, 1H), 8.28 (d, J =7.3 Hz, 1H), 7.96 - 7.90 (m, 1H), 7.82 (d, J = 7.3 Hz, 1H), 7.77 (dd, J =8.8, 1.1 Hz, 1H), 7.47 (t, J = 8.8 Hz, 1H), 7.10 (t, J = 7.1 Hz, 1H), 6.87 (d, J = 7.2 Hz, 2H), 2.21 (s, 6H) ppm.13 C NMR (400 MHz, CDCl3) δ 159.03,153.95, 146.01, 145.48, 138.06, 137.98, 136.94, 130.91, 130.46, 130.05,127.92, 126.89, 126.50, 124.61, 124.57, 121.15, 29.41, 29.38, 22.20, 22.18ppm. Anal. Calcd for C 22 H 23 ClN2: C, 75.31; H, 6.61; Cl, ​​10.10; N, 7.98. Found: C, 75.30; H, 6.60; Cl, ​​10.8; N, 7.95 Weigh out [NiBr2(DME)] (0.468 g, 1.0 mmol), add 10 mL of anhydrous dichloromethane, add ligand L5 (0.386 g, 1.1 mmol), and stir for 12 hours at room temperature under nitrogen protection. After the reaction is complete, remove the solvent, wash with diethyl ether, and filter to give product C5 0.751 g, yield 88%. 1 H NMR (400 MHz, C6D6): δ 8.50 (d, J = 8.0 Hz,1H), 8.10 (d, J = 8.0 Hz, 1H), 7.54 (dd, J = 7.1, 1.1 Hz, 1H), 7.46 (s, 1H),7.36 - 7.31 (m, 1H), 7.24 (t, J = 7.6 Hz, 1H), 7.20 - 7.13 (m, 1H), 6.82 (d,J = 7.6 Hz, 2H), 3.32 (heptd, J = 6.2, 0.7 Hz, 2H), 1.26 (d, J = 6.2 Hz,13H). 13 C NMR (400 MHz, C6D6): δ 152.49, 149.22, 141.64, 141.60, 138.07,137.79, 136.81, 136.72, 128.78, 127.31, 126.48, 125.68, 125.39, 125.07,125.04, 124.99, 29.79, 29.76, 23.63, 23.62, 23.61 ppm. Anal. Calcd forC 22 H 23Br2ClN2Ni: C, 46.41; H, 4.07; Br, 28.07; Cl, ​​6.23; N, 4.92. Found: C, 46.40;

[0031] Example 6: C2-catalyzed ethylene oligomerization Inside a glove box, 2 μmol of catalyst C2 was added to a 350 mL thick-walled glass reactor equipped with a magnetic induction device. The reactor was then connected to a high-pressure line, degassed under vacuum, and purged with ethylene at 1 bar pressure. 20 mL of toluene was injected via syringe, and the temperature was raised to 90 °C. After injecting 200 μmol of diethylaluminum chloride, ethylene was introduced at 5 bar pressure to initiate the oligomerization reaction. The ethylene pressure was maintained constant during the reaction through continuous feeding. After reaching the preset oligomerization time, the reactor was cooled to -40 °C and the gas was vented. A small amount of the catalyst mixture was collected and immediately quenched with a 5% aqueous solution of hydrogen chloride at 0 °C. The supernatant was analyzed by gas chromatography to determine the distribution of the resulting oligomers, and the oligomer yield was calculated based on the mass of toluene. Polymerization activity: 0.9 × 10⁻⁶ 4 g·mol -1 (Ni)·h -1 Butene selectivity >99%.

[0032] Example 7: C2-catalyzed ethylene polymerization The polymerization process and reaction conditions were the same as in Example 6, with ethylaluminum dichloride as the co-catalyst. Polymerization activity: 13.5 × 10⁻⁶ 4 g·mol -1 (Ni)·h -1 Butene selectivity >99%.

[0033] Example 8: C2-catalyzed ethylene polymerization The polymerization process and conditions were the same as in Example 7, with ethyl aluminum chloride used at a rate of 150 μmol. Polymerization activity: 11.2 × 10⁻⁶ 4 g·mol -1 (Ni)·h -1 Butene selectivity >99%.

[0034] Example 9: C2-catalyzed ethylene polymerization The polymerization process and conditions were the same as in Example 7, with ethyl aluminum chloride used at a rate of 300 μmol. Polymerization activity: 12.4 × 10⁻⁶ 4 g·mol -1 (Ni)·h -1 Butene selectivity >99%.

[0035] Example 10: C2-catalyzed ethylene polymerization The polymerization process and conditions were the same as in Example 7, with 400 μmol of ethyl aluminum chloride used. Polymerization activity: 1.3 × 10⁻⁶ 4 g·mol -1 (Ni)·h -1 Butene selectivity >99%.

[0036] Example 11: C2-catalyzed ethylene polymerization The polymerization process and conditions were the same as in Example 7, with a reaction temperature of 30 °C. Polymerization activity: 1.5 × 10⁻⁶ 4 g·mol -1 (Ni)·h -1 Butene selectivity >99%.

[0037] Example 12: C2-catalyzed ethylene polymerization The polymerization process and conditions were the same as in Example 7, with a reaction temperature of 50 °C. Polymerization activity: 3.5 × 10⁻⁶ 4 g·mol -1 (Ni)·h -1 Butene selectivity >99%.

[0038] Example 13: C2-catalyzed ethylene polymerization The polymerization process and conditions were the same as in Example 7, with a reaction temperature of 70 °C. Polymerization activity: 6.0 × 10⁻⁶ 4 g·mol -1 (Ni)·h -1 Butene selectivity >99%.

[0039] Example 14: C1-catalyzed ethylene polymerization The polymerization process and reaction conditions were the same as in Example 7, with C1 catalyst. Polymerization activity: 7.0 × 10⁻⁶ 4 g·mol -1 (Ni)·h -1 Butene selectivity >99%.

[0040] Example 15: C3-catalyzed ethylene polymerization The polymerization process and reaction conditions were the same as in Example 7, with C3 as the catalyst. Polymerization activity: 34.6 × 10⁻⁶ 4 g·mol -1 (Ni)·h -1 Butene selectivity >99%.

[0041] Example 16: C4-catalyzed ethylene polymerization The polymerization process and reaction conditions were the same as in Example 7, with C4 catalyst. Polymerization activity: 3.3 × 10⁻⁶4 g·mol -1 (Ni)·h -1 Butene selectivity >99%.

[0042] Example 17: C5 Catalytic Ethylene Polymerization The polymerization process and reaction conditions were the same as in Example 7, with C5 catalyst. Polymerization activity: 12.1 × 10⁻⁶ 4 g·mol -1 (Ni)·h -1 Butene selectivity >99%.

Claims

1. A class of quinoline-imine-based nickel metal catalysts, the structure of which is shown in formula (І): （Ⅰ）， in, X is selected from bromine and chlorine; R 1 Selected from hydrogen, isopropyl, chlorine, fluorine; R 2 Selected from methyl, chlorine, isopropyl, and diphenylmethyl.

2. The preparation method of the quinoline-imine-based nickel metal catalyst according to claim 1 comprises the following steps: under a nitrogen atmosphere, dissolving the nickel precursor [NiBr2(DME)] in 20-80 mL of anhydrous solvent, adding 1.0-1.1 molar equivalents of quinoline-imine ligand, and reacting at room temperature for 12 hours under nitrogen protection; after the reaction is completed, removing the solvent under reduced pressure, washing with diethyl ether, and obtaining the quinoline-imine-based nickel metal catalyst.

3. The preparation method according to claim 2, characterized in that: The anhydrous solvent is selected from diethyl ether, toluene, n-hexane, xylene, and benzene.

4. A method for olefin oligomerization, characterized in that: The catalyst used is the quinoline-imine nickel metal catalyst as described in claim 1.

5. The method according to claim 4, characterized in that: The olefin monomer is ethylene.

6. The method according to claim 4, characterized in that: The quinoline-imine nickel metal catalyst requires the use of a co-catalyst for catalysis. The co-catalyst is one or more of ethyl aluminum chloride, diethyl aluminum chloride, methylaluminoxane, and trimethylaluminum.

7. The method according to claim 4, characterized in that: The reaction temperature is 30-90 ℃, the reaction pressure is 0.1-0.5 MPa, and the reaction solvent is one or more of toluene, n-hexane, and heptane.

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