Preparation method and application of quinoline pyridine nickel precatalyst

Abstract

The application provides a quinoline pyridine nickel pre-catalyst and a preparation method and application thereof. The nickel pre-catalyst is 8-(2,6-di(aryl)-3,4,5-trifluorophenyl) imino-5,6,7-trihydroquinoline pyridine. Under the protection of inert gas, a ligand L is prepared by using 5,6,7-trihydroquinoline-8-ketone and synthetic aniline A, and the ligand L is reacted with (DME)NiBr2 to prepare a series of nickel pre-catalysts Ni R ; the nickel pre-catalyst is activated by methylaluminoxane (MAO) and used for ethylene polymerization catalytic performance experiment, the nickel pre-catalyst shows high catalytic activity (3.1×10 6 g mol ‑1 h ‑1 ), and produces controllable polyethylene with chain walking (branching degree = 58-90 / 1000C), chain transfer (polymer M w = 0.7-2.8 kg mol ‑1 ) and chain termination reaction (vinylidene / ethylene = 83.4-93.6%) and the like. It is worth noting that the beta-elimination reaction is the main chain termination mode in the system, so that the obtained polyethylene can change from polyethylene wax to viscous oil with the change of polymerization temperature, and further produce polyethylene with a higher internal double bond ratio.

Description

TECHNICAL FIELD

[0001] The present application relates to an olefin polymerization catalyst, in particular to a quinoline pyridine nickel pre-catalyst for obtaining low molecular weight branched polyethylene by enhancing steric hindrance and electronic effect, and a preparation method and application thereof. BACKGROUND

[0002] The discovery of nickel / palladium catalyzed ethylene polymerization, combined with the introduction of the concept of chain walking, makes it possible to synthesize various polyethylene products from ethylene alone. Chain walking reactions can produce oligomers with branches, as well as high to ultrahigh molecular weight polyethylene containing different alkyl branches. Notably, the process can transfer the beta-elimination reaction from the terminal position to other positions within the polymer chain, producing polyethylene with vinyl, vinylidene or vinylidene branched groups. These highly branched low molecular weight polyethylene waxes are widely used in additives, lubricants, comonomers, functional polymers and coatings. This is due to the effective control of chain walking characteristics and related reactions during polymerization. Studies have shown that chain walking and related reactions during polymerization can be effectively regulated by changing the ligand structure and reaction conditions. Among them, alpha-diimine and imino pyridine-based catalysts show strong chain walking reaction tendency, unlike alpha-diimine nickel catalysts, nickel catalysts based on imino pyridine groups are prone to chain transfer, resulting in low molecular weight polyethylene, which may be due to less spatial protection of the active species to the axial site. SUMMARY

[0003] The purpose of the present application is to provide a quinoline pyridine nickel pre-catalyst and a preparation method and application thereof, which is used as a catalyst for preparing low molecular weight branched polyethylene.

[0004] To achieve the above purpose, the present application provides the following technical solutions:

[0005] A quinoline pyridine nickel pre-catalyst, the structural formula of which is:

[0006]

[0007] The preparation method of the quinoline pyridine nickel pre-catalyst. The specific steps are as follows:

[0008] (1) Synthesis of aniline compound: 3,4,5-trifluoroaniline and benzhydrol compound are stirred uniformly, then anhydrous zinc chloride hydrochloride solution is slowly added dropwise, and the reaction is carried out at 140-160℃ for 0.5-4h, and the reaction product is purified to obtain solid product A;

[0009] (2) Preparation of ligand: 5,6,7-trihydroquinolin-8-one, synthetic aniline A compound and a catalytic amount of 4-methylbenzenesulfonic acid are mixed, and toluene is added as a solvent. After stirring under reflux at 110°C for 10-12 hours, all volatiles are removed under reduced pressure; the obtained mixture is purified and then chromatographed on a silica gel column, eluted with a eluent (n-hexane: ethyl acetate = 25:1), and a yellow powdery ligand L is collected;

[0010] (3) Preparation of nickel precatalyst: under an inert atmosphere, equimolar amounts of L and (DME)NiBr2 are added to a Schlenk tube, and then 10 ml of anhydrous dichloromethane is added; the mixture is stirred at room temperature for 24 hours, and the solvent is removed under reduced pressure; the complex is precipitated by adding diethyl ether, filtered, washed with diethyl ether three times, and dried to obtain a solid nickel precatalyst Ni R .

[0011] In step (1), the molar ratio of 3,4,5-trifluoroaniline to benzhydrol compound is 1:2; the catalytic amount of anhydrous zinc chloride hydrochloride solution, the reaction temperature is 140-160°C, and the reaction time is 0.5-4h. In step (2), the molar ratio of 5,6,7-trihydroquinolin-8-one to synthetic aniline A compound is 1:1, and the reaction time is 10-12 hours; in step (3), the molar ratio of L to (DME)NiBr2 is 1:1-1.5.

[0012] The application of the quinolinopyridine nickel precatalyst in ethylene polymerization is that the quinolinopyridine nickel precatalyst is used as a main catalyst, alkylaluminoxane (methylaluminoxane MAO, modified methylaluminoxane MMAO) or chlorinated alkylaluminum (diethylaluminum chloride DEAC, hemi-ethylaluminum chloride EASC) is used as a cocatalyst, the molar ratio of the main catalyst to the cocatalyst is 1:200-1:3000, the polymerization temperature is 0-100°C, the polymerization time is 5-60 minutes, the polymerization pressure is 0.1-1.0 MPa, and ethylene is catalytically polymerized.

[0013] The preferred application of the present application is that the quinolinopyridine nickel precatalyst is used as a main catalyst, and methylaluminoxane MAO is used as a cocatalyst. The preferred conditions are that a composite catalytic system is formed with the molar ratio of 1:2000 of the main catalyst to the cocatalyst, the reaction temperature is controlled to be 30-50°C, the reaction time is controlled to be 5-60 minutes, the polymerization pressure is 0.1-1.0 MPa, and ethylene is catalytically polymerized.

[0014] Compared with the prior art, the present application has the beneficial effects that the quinolinopyridine nickel precatalyst can realize the regulation of the molecular weight, the branching degree and the solubility temperature of the polymer by enhancing the steric hindrance and the electronic effect. The complex is applied to the ethylene polymerization reaction, and under the action of the cocatalyst MAO, the catalytic activity is as high as 3.1 x 10 6 g mol-1 h -1 , and produces polymers with chain walking (branching degree = 58 ~ 90 / 1000C), chain transfer (polymer M w =0.7~2.8kg mol -1 ) and chain termination reactions (vinylidene / vinyl = 83.4-93.6%). Notably, the chain-walking reaction and chain termination rates during polymerization vary with reaction temperature, allowing the resulting polyethylene to have physical properties ranging from polyethylene wax to viscous oil. Most importantly, β-elimination is the primary chain termination mechanism, resulting in polyethylene with a high internal double bond ratio (vinylidene / vinyl ratio as high as 93.6%). BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 The complex Ni prepared in Example 1 (3) F Schematic diagram of the crystal structure.

[0016] Figure 2 The thermal NMR carbon spectrum and microstructure of the polymer obtained in Example 5 (1) are shown.

[0017] Figure 3 The H-NMR spectrum and microstructure of the polymer obtained in Example 5 (2) are shown. DETAILED DESCRIPTION

[0018] The present invention is described below by means of specific embodiments, but the protection scope of the present invention is not limited thereto.

[0019] The experimental methods used in the following examples are all conventional methods, the raw materials used are all commercially available, and the ligands and complexes synthesized below are all confirmed by nuclear magnetic resonance, infrared, and elemental analysis.

[0020] The synthesis of the ligand and nickel precatalyst in the following examples is carried out according to the following reaction equation:

[0021]

[0022] Example 1

[0023] Preparation of complexes

[0024] (1) Preparation of aniline A: 3,4,5-trifluoroaniline (40 mmol) and benzhydrol (80 mmol) were added to a 300 mL round-bottom flask. The oil bath temperature was raised to 70°C and stirred until the mixture melted. The temperature was then raised to 160°C and 2 mL of hydrochloric acid solution containing anhydrous zinc chloride was slowly added dropwise. The reaction was continued for 1 h. The reaction product was purified to obtain a white powder AH.

[0025] A-F, A-Cl, A-Me and A- t Bu was prepared as A-H

[0026] Characterization data for aniline A-H: 1 H NMR (400 MHz, Chloroform-d) δ 7.26 (dd, J = 13.9, 6.7 Hz, 13H), 7.15 (d, J = 7.4 Hz, 8H), 5.83 (s, 2H), 3.43 (s, 2H).

[0027] Characterization data for aniline A-F: 1 H NMR (600 MHz, Chloroform-d) δ 7.10 (dd, J = 8.6, 5.3 Hz, 8H), 7.04 - 6.96 (m, 8H), 5.75 (s, 2H), 3.41 (s, 2H).

[0028] Characterization data for aniline A-Cl: 1 H NMR (300 MHz, Chloroform-d) δ 7.28 (d, J = 8.4 Hz, 8H), 7.05 (d, J = 8.3 Hz, 8H), 5.71 (s, 2H), 3.39 (s, 2H).

[0029] Characterization data for aniline A-Me: 1 H NMR (400 MHz, Chloroform-d) δ 7.09 (d, J = 7.9 Hz, 8H), 7.03 (d, J = 8.0 Hz, 8H), 5.74 (s, 2H), 3.45 (s, 2H), 2.33 (s, 12H).

[0030] Characterization data for aniline A- t Bu: 1 H NMR (600 MHz, Chloroform-d) δ 7.28 (d, J = 8.5 Hz, 8H), 7.08 (d, J = 8.4 Hz, 8H), 5.80 (s, 2H), 3.44 (s, 2H), 1.30 (s, 36H).

[0031] (2) Preparation of ligand L: 5,6,7-trihydroquinolin-8-one (3.40 mmol), 2,6-diphenylmethyl-3,4,5-trifluoroaniline (3.40 mmol) and catalytic amount of p-toluenesulfonic acid (1 mmol) were mixed and toluene was added as solvent. After stirring at reflux at 110 °C for 12 hours, all volatiles were removed under reduced pressure. Purification of the product gave the target ligand L-H as a light yellow crystalline solid.

[0032] L-F, L-Cl, L-Me and L- tBu was prepared by the same method as L-H

[0033] Characterization data of ligand L-H: 1 H NMR (600 MHz, CDC13.TMS) δ 8.79 (s, 1H), 7.49 (s, 1H), 7.30 (d, J = 46.3 Hz, 4H), 7.09 - 6.82 (m, 16H), 5.44 (d, J = 2.5 Hz, 2H), 3.17 - 3.01 (m, 1H), 2.17 (d, J = 7.3 Hz, 1H), 1.41 (t, J = 7.3 Hz, 2H). 13 C NMR (151 MHz, Chloroform-d) δ 143.46, 140.59, 129.67, 128.92, 128.57, 128.02, 126.89, 126.21, 125.62, 49.09, 31.16, 28.83, 20.40. FT-IR (KBr, cm -1 ): 3438.5 (s), 1649.8 (vC=N, s), 1605 (m), 1495.5 (s), 1479.3 (s), 1449.8 (m), 1221.8 m), 1121.5 (m), 1107.7 (m), 1034.6 (w), 1008.1 (w), 983.5 (m), 702.7 (s), 680.9 (w).

[0034] Anal. Calcd. for C 41 H 31 F3N2[H2O + MeOH]: C, 76.58; H, 5.66; N, 4.25; Found. C, 77.17; H, 5.24; N, 4.33.

[0035] Characterization data of ligand L-F: 1 H NMR (600 MHz, CDC13.TMS) δ 8.79 (s, 1H), 7.49 (s, 1H), 7.30 (d, J = 46.3 Hz, 4H), 7.09 - 6.82 (m, 16H), 5.44 (d, J = 2.5 Hz, 2H), 3.17 - 3.01 (m, 1H), 2.17 (d, J = 7.3 Hz, 1H), 1.41 (t, J = 7.3 Hz, 2H). 13C NMR(151MHz,Chloroform-d)δ162.69,162.36,161.05,160.73,138.71,136.19,131.03,130.97,129.98,129.93,125.93,115.98,115.84,115.02,114.88,47.61,31.31,28.87,20.58.FT-IR(KBr,cm -1 ):3434.5(s),1656.9(νC=N,m),1606(m),1509(s),1483(s),1310(s),1228(m),1218.5(m),1181(s),1008(w),922(w),672(w),570(m).Anal.Calcd.for C 41 H 27 F7N2[CH2Cl2+H2O]:C,64.38;H,3.99;N,3.57;Found.C,64.22;H,3.80;N,3.68.

[0036] 配体L-Cl的表征数据: 1 H NMR(600MHz,Chloroform-d)δ8.83–8.73(m,1H),7.53(d,J=7.8Hz,1H),7.37(dd,J=7.8,4.6Hz,1H),7.25–6.94(m,16H),5.43(s,2H),2.43(t,J=6.1Hz,2H),1.03–0.97(m,2H),0.74(p,J=6.1Hz,2H). 13 C NMR(151MHz,Chloroform-d)δ141.13,138.57,133.15,132.45,130.80,129.84,129.22,128.36,47.86,45.91,31.40,29.85,28.87,20.58,1.17.FT-IR(KBr,cm -1 ):3052(w),2957(m),1642(νC=N,m),1600(m),1565(w),1500(s),1403(m),1259(m),1094(m),815(s),732(w),684(w).Anal.Calcd.forC 41 H 27 Cl4F3N2[EtOH+2H2O]:C,62.33;H,4.50;N,3.38;Found.C,62.73;H,4.85;N,3.41.

[0037] Characterization data for ligand L-Me: 1 H NMR (600 MHz, Chloroform-d) δ 8.80 - 8.72 (m, 1H), 7.47 (d, J = 7.7 Hz, 1H), 7.37 - 7.28 (m, 1H), 7.03 - 6.97 (m, 8H), 6.95 (t, J = 7.2 Hz, 8H), 5.44 (s, 2H), 2.28 (d, J = 8.0 Hz, 12H), 1.42 (t, J = 7.3 Hz, 2H), 0.90 (q, J = 7.8, 7.0 Hz, 2H), 0.61 (p, J = 6.3 Hz, 2H). 13 C NMR (151 MHz, Chloroform-d) δ 140.73, 137.77, 136.24, 135.56, 129.48, 129.45, 128.68, 128.45, 125.45, 48.33, 45.92, 31.14, 28.92, 21.13, 20.39, 8.76, 1.16. FT-IR (KBr, cm -1 ): 3090 (w), 3049 (w), 2928 (w), 1639 (vC=N, m), 1598 (s), 1515 (m), 1480 (s), 1436 (w), 1327 (m), 1297 (m), 1265 (w), 1188 (m), 1044 (w), 1024 (m), 988 (w), 817 (m), 732 (w), 688 (w). Anal. Calcd. For C 45 H 39 F3N2[ethyl acetate]: C, 78.18; H, 6.29; N, 3.72; Found. C, 78.07; H, 5.94; N, 4.07.

[0038] Characterization data for ligand L-tBu: 1 H NMR (600 MHz, Chloroform-d) δ 8.76 (d, J = 4.5 Hz, 1H), 7.45 (d, J = 7.6 Hz, 1H), 7.31 (d, J = 8.3 Hz, 1H), 7.22 (d, J = 8.2 Hz, 4H), 7.18 (d, J = 8.0 Hz, 4H), 6.99 (dd, J = 8.4, 2.0 Hz, 8H), 5.45 (s, 2H), 2.26 (t, J = 6.1 Hz, 2H), 1.31 (d, J = 1.2 Hz, 2H), 1.27 (d, J = 1.1 Hz, 18H), 1.26 (d, J = 3.2 Hz, 2H), 1.24 (d, J = 1.2 Hz, 18H).13 C NMR (151 MHz, Chloroform-d) δ 149.56, 148.73, 140.55, 137.88, 129.25, 128.14, 125.71, 124.82, 48.24, 34.52, 34.45, 31.52, 31.49, 31.01, 20.36, 1.16. FT-IR (KBr, cm -1 ): 2963 (w), 2860 (w), 1642 (vC=N, m), 1596 (w), 1518 (m), 1480 (s), 1362 (w), 1274 (m), 1106 (m), 991 (w), 844 (m), 697 (w). Anal. Calcd. for C 57 H 63 F3N2[2 EtOH]: C, 79.18; H, 8.17; N, 3.03; Found. C, 79.27; H, 8.02; N, 3.12.

[0039] (3) Preparation of nickel pre-catalyst Ni R : L-H (0.49 mmol) and (DME)NiBr2(0.49 mmol) were added to a Schlenk tube under inert gas protection, then 10 ml of anhydrous dichloromethane was added. The mixture was stirred at room temperature for 12 hours, and the solvent was removed under reduced pressure. The complex was precipitated by adding ether, and a dark red solid powder of Ni H was obtained by filtration.

[0040] Ni F , Ni Cl , Ni Me and Ni tBu were prepared by the same method as Ni H

[0041] The characterization data are as follows:

[0042] The characterization data of pre-catalyst Ni H : FT-IR (KBr, cm -1 ): 3058 (w), 3019 (w), 1609 (vC=N, m), 1586 (w), 1483 (s), 1450 (m), 1350 (w), 1300 (w), 1212 (w), 1109 (m), 1035 (w), 988 (m), 947 (m), 832 (w), 767 (w). Anal. Calcd. for C 41 H 31F3N2NiBr2[CH2Cl2]:C,55.31;H,3.65;N,3.07;Found.C,55.89;H,3.93;N,3.16.

[0043] Precatalyst Ni F Characterization data: FT-IR (KBr, cm -1 ):3055(w),2966(w),1603(νC=N,m),1583(w),1512(s),1486(s),1344(w),1294( w),1224(s),1168(m),1100(m),994(m),847(m),729(w),611(w).Anal.Calcd.for C 41 H 27 F7N2NiBr2:C,54.77;H,3.03;N,3.12;Found.C,54.59;H,3.00;N,3.14.

[0044] Precatalyst Ni Cl Characterization data: FT-IR (KBr, cm -1 ):3052(w),2957(m),1614(νC=N,m),1576(m),1488(m),1400(m),1343(w),1259(m),1094(m),815(s),732(w),684(w).Anal.Calcd.For C 41 H 27 Cl4F3N2NiBr2[CH2Cl2+MeOH]:C,47.74;H,3.07;N,2.59;Found.C,47.44;H,3.07;N,2.69.

[0045] Precatalyst Ni Me Characterization data: FT-IR (KBr, cm -1 ):3016(w),1615(νC=N,s),1586(m),1512(s),1486(s),1330(w),1297(w),1212(w),1112(s),997(m),815(m),720(m),573(m).Anal.calcd for C 45 H 39 F3N2NiBr2[CH2Cl2+MeOH]:C,56.44;H,4.53;N,2.80;Found.C,56.83;H,4.55;N,3.25.

[0046] Precatalyst NitBu Characterization data: FT-IR (KBr, cm -1 ):3055(w),2966(m),1612(νC=N,m),1577(m),1479(m),1365(m),1271(w),1259(m),1094(m),815(s),732(w),684(w).Anal.Calcd.For C 57 H 63 F3N2NiBr2[2H2O]:C,62.94;H,6.21;N,2.58;Found.C,62.94;H,5.34;N,2.85.

[0047] Example 2

[0048] Using pre-catalyst Ni F Ethylene polymerization with different cocatalysts:

[0049] (1) Under ethylene atmosphere, 20 mL of toluene and 30 mL of nickel catalyst Ni F A 3 μmol toluene solution and 3.60 mL of co-catalyst MAO (1.67 mol / L toluene solution) were added sequentially to a 300 mL stainless steel autoclave. 50 mL of toluene was added to bring the total volume of the reaction solution to 100 mL. At this point, Al / Ni = 2000. When the polymerization temperature reached 30°C, ethylene was added to the reactor and the polymerization reaction began. The ethylene pressure was maintained at 10 atm at 30°C for 30 minutes. The reaction solution was neutralized with an ethanol solution acidified with 5% hydrochloric acid, filtered, and the polymer precipitate was washed several times with ethanol, dried under vacuum, and weighed. Polymerization activity: 10.1×10 5 g mol -1 h -1 , polymer T m =76℃(T m is the melting temperature of the polymer, obtained by DSC test), the polymer molecular weight M w =1.4 kg·mol -1 , M w / M n =1.80(M w is the weight-average molecular weight of the polymer, obtained by temperature-elevated GPC testing).

[0050] (2) The implementation method is the same as above, except that 2.31 mL of MMAO (2.60 mol / L toluene solution) is used as the co-catalyst, and Al / Ni is 2000. Polymerization activity: 8.0×10 5 g mol -1 h -1 , polymer Tm = 99.0°C, polymer molecular weight M w = 1.8 kg-mol -1 , M w / M n = 1.44, polymer T m = 71 °C,.

[0051] (3) The implementation method is the same as above, except that the concentration of DEAC (2.0 mol / L n-hexane solution) is 0.9 mL, and Al / Ni = 600. Polymerization activity: 2.6 x 10 5 g-mol -1 h -1 , polymer T m = 71 °C, polymer molecular weight M w = 2.8 kg-mol -1 , M w / M n = 1.65, polymer T m = 87 °C / 119 °C.

[0052] (4) The implementation method is the same as above, except that the concentration of EASC (0.4 mol / L n-hexane solution) is 4.5 mL, and Al / Ni = 600. Polymerization activity: 2.0 x 10 5 g-mol -1 h -1 , polymer T m = 93.2 °C, polymer molecular weight M w = 2.2 kg-mol -1 , M w / M n = 1.56, polymer T m = 88 °C.

[0053] Example 3

[0054] Ethylene polymerization using pre-catalyst Ni F and different Al / Ni of co-catalyst MAO:

[0055] (1) The implementation method is the same as Example 2, except that the amount of co-catalyst MAO (1.67 mol / L toluene solution) is 1.80 mL, and Al / Ni = 1000. Polymerization activity: 4.0 x 10 5 g-mol –1 h –1 , polymer molecular weight M w = 1.8 kg-mol -1 , M w / M n = 1.53, polymer T m= 74°C / 112°C.

[0056] (2) The implementation method is the same as above, except that the amount of co-catalyst MAO (1.67 mol / L toluene solution) is 2.70 mL, and Al / Ni = 1500. Polymerization activity: 4.3 x 10 5 g-mol –1 -h –1 , polymer M w = 1.7 kg-mol –1 , M w / M n = 1.64 1 , polymer T m = 75°C / 110°C.

[0057] (3) The implementation method is the same as above, except that the amount of co-catalyst MAO (1.67 mol / L toluene solution) is 3.15 mL, and Al / Ni = 1750. Polymerization activity: 7.7 x 10 5 g-mol –1 -h –1 , polymer M w = 1.5 kg-mol –1 , M w / M n = 1.62, polymer T m = 70°C / 110°C.

[0058] (4) The implementation method is the same as above, except that the amount of co-catalyst MAO (1.67 mol / L toluene solution) is 4.04 mL, and Al / Ni = 2250. Polymerization activity: 6.0 x 10 5 g-mol –1 -h –1 , polymer M w = 0.8 kg-mol –1 , M w / M n = 2.00.

[0059] (5) The implementation method is the same as above, except that the amount of co-catalyst MAO (1.67 mol / L toluene solution) is 4.49 mL, and Al / Ni = 2500. Polymerization activity: 5.3 x 10 5 g-mol –1 -h –1 , polymer M w = 0.7 kg-mol –1 , M w / M n = 1.59.

[0060] Example 4

[0061] Using pre-catalyst Ni F Ethylene polymerization at different temperatures with cocatalyst MAO:

[0062] (1) The implementation method is the same as that of Example 2, except that: 3.60 mL of cocatalyst MAO (1.67 mol / L toluene solution) was used, Al / Ni was 2000, the reaction time was 30 min, the polymerization temperature was 40° C., and the polymerization activity was 0.3×10 5 g·mol –1 ·h –1 , polymer M w =0.9 kg·mol –1 , M w / M n =1.53, polymer T m =73℃ / 119℃.

[0063] (2) The implementation method is the same as above, except that: polymerization activity: 0.1×10 5 g·mol –1 ·h –1 , polymer M w =0.9 kg·mol –1 , M w / M n =1.33.

[0064] Example 5

[0065] Ethylene polymerization using five nickel precatalysts and cocatalyst MAO under optimal conditions:

[0066] (1) The implementation method is the same as in Example 2, except that: the nickel catalyst Ni H As the main catalyst, the amount of co-catalyst MAO (1.67 mol / L toluene solution) was 3.60 mL, Al / Ni = 2000, the reaction time was 30 min, the polymerization temperature was 30 ° C, and the polymerization activity was 1.0 × 10 5 g·mol –1 ·h –1 , polymer M w =1.6 kg·mol –1 , M w / M n =1.83.

[0067] (2) The implementation method is the same as above, except that: nickel catalyst Ni Cl As the main catalyst, the amount of cocatalyst MAO (1.67 mol / L toluene solution) was 3.60 mL, Al / Ni = 2000, the reaction time was 30 min, the polymerization temperature was 30 ° C, and the polymerization activity was 1.1 × 10 5g-mol –1 ·h –1 , polymer M w = 1.6 kg-mol –1 , M w / M n = 1.84.

[0068] (3) The implementation method is the same as above, except that the nickel catalyst Ni Me is used as the main catalyst, the amount of the cocatalyst MAO (1.67 mol / L toluene solution) is 3.60 mL, Al / Ni = 2000, the reaction time is 30 min, the polymerization temperature is 30°C, and the polymerization activity is 1.8 x 10 5 g-mol –1 ·h –1 , polymer M w = 1.7 kg-mol –1 , M w / M n = 1.83.

[0069] (4) The implementation method is the same as above, except that the nickel catalyst Ni tBu is used as the main catalyst, the amount of the cocatalyst MAO (1.67 mol / L toluene solution) is 3.60 mL, Al / Ni = 2000, the reaction time is 30 min, the polymerization temperature is 30°C, and the polymerization activity is 1.7 x 10 5 g-mol –1 ·h –1 , polymer M w = 2.2 kg-mol –1 , M w / M n = 1.61.

Claims

1. A quinoline pyridine nickel precatalyst, characterized in that The structural formula is: ， wherein: R is independently selected from one of a hydrogen atom, a methyl group, a tert-butyl group, a fluorine atom and a chlorine atom.

2. The method for preparing a quinoline pyridine nickel precatalyst according to claim 1, wherein: The steps include: (1) Synthesis of aniline compounds: After 3,4,5-trifluoroaniline and benzhydrol compounds are stirred evenly, anhydrous zinc chloride hydrochloric acid solution is slowly added dropwise. The reaction is continued at 140 ℃ ~ 160 ℃ for 0.5 ~ 4 h. The reaction product is purified to obtain solid product aniline A; (2) Preparation of the ligand: 5,6,7-trihydroquinolin-8-one, synthesized aniline A, and a catalytic amount of 4-methylbenzenesulfonic acid were mixed, and toluene was added as a solvent; after stirring and refluxing at 110°C for 10-12 hours, all volatiles were removed under reduced pressure; the obtained mixture was purified and then eluted by silica gel column chromatography with an eluent to collect the yellow powdered ligand L; (3) Preparation of nickel complex: Under an inert atmosphere, equimolar amounts of ligand L and (DME)NiBr2 were added to a Schlenk tube, followed by 10 ml of anhydrous dichloromethane. The mixture was stirred at room temperature for 24 hours, and the solvent was removed under reduced pressure. The complex was precipitated by adding diethyl ether, filtered, washed three times with diethyl ether, and dried to obtain a solid nickel complex Ni. R That is, nickel pre-catalyst.

3. The method according to claim 2, wherein In the step (1), the molar ratio of 3,4,5-trifluoroaniline to benzhydrol compounds is 1:2; anhydrous zinc chloride hydrochloric acid solution is used as a catalytic amount, the reaction temperature is 140°C to 160°C, and the reaction time is 0.5 to 4 hours; in the step (2), the molar ratio of 5,6,7-trihydroquinolin-8-one to the synthesized aniline A is 1:1, and the reaction time is 10-12 hours; the raw materials and the ratio of the eluent are: n-hexane: ethyl acetate = 25:1; and in the step (3), the molar ratio of the ligand L to (DME)NiBr2 is 1:1-1.

5.

4. Use of a quinolinepyridine nickel precatalyst as claimed in claim 1 in ethylene polymerization.

5. The use according to claim 4, characterized in that: The method uses quinoline pyridine nickel precatalyst as the main catalyst, alkylaluminoxane or alkylaluminum chloride as the cocatalyst, the molar ratio of the main catalyst to the cocatalyst is 1:200-1:3000, the polymerization temperature is 0-100°C, the polymerization time is 5-60 minutes, the polymerization pressure is 0.1-1.0 MPa, and catalyzes ethylene polymerization.

6. The use according to claim 5, characterized in that: The alkylaluminoxane is methylaluminoxane MAO or modified methylaluminoxane MMAO; the alkylaluminum chloride is diethylaluminum chloride DEAC or sesquiethylaluminum chloride EASC.

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