Method for producing polyethylene wax based on nickel metal catalyst

Abstract

The invention provides a method for producing polyethylene wax based on a nickel metal catalyst, which comprises the following steps: fully contacting ethylene with the nickel metal catalyst so as to carry out polymerization reaction on the ethylene to obtain the polyethylene wax, wherein the nickel metal catalyst comprises a main catalyst and a co-catalyst in a molar ratio of 1: (100-1000), the co-catalyst is aluminum alkyl, and the main catalyst is a bidentate nitrogen-doped nickel complex. The bidentate aza-nickel complex used in the invention can ensure that the catalyst can prepare a low molecular weight polyethylene wax product with low molecular weight and narrow distribution at high activity under high pressure.

Description

Technical Field

[0001] This invention relates to the field of olefin catalytic polymerization technology, and specifically to a method for producing polyethylene wax based on a nickel metal catalyst. Background Technology

[0002] Polyethylene is one of the most widely used polymer materials, with different applications depending on its structure and molecular weight. For example, high-molecular-weight linear high-density polyethylene (HDPE) can be used as pipes, while linear low-density polyethylene (LLDPE), due to the introduction of α-olefins, has branches in its main chain, significantly improving its toughness and making it suitable for membrane and pipe applications. Low-density polyethylene, on the other hand, contains highly branched chains and has even better toughness, primarily used as a membrane material. Besides branching, molecular weight also significantly influences the applications of polyethylene. Generally, high-molecular-weight polymers, due to their excellent mechanical properties, can be used directly as plastics and elastomers; while low-molecular-weight polyethylene waxes can be used as color masterbatches and hot melt adhesives.

[0003] Existing technologies lack methods for flexibly switching between the production of highly branched polyethylene oil and narrowly distributed low molecular weight polyethylene wax using a single reaction apparatus. CN101074393A discloses a method for simultaneously producing petroleum wax and high viscosity index lubricating oil base oil. The feedstock oil is contacted with a solvent and a dewaxing aid, and undergoes 2-3 stages of dewaxing at a relatively high temperature to obtain petroleum wax, dewaxed oil from the first stage of dewaxing, and wax under-wax oil from the second and third stages of dewaxing. The dewaxed oil and wax under-wax oil are then contacted with hydrogen and a hydrotreating catalyst for hydrotreating. The resulting oil is then contacted with a hydrosaturating catalyst for hydrosaturation. The hydrosaturated oil is then subjected to atmospheric pressure flash distillation. The light oil obtained from the flash distillation is used as a special solvent oil, while the heavy oil is contacted with hydrogen and an isomerization dewaxing catalyst for isomerization dewaxing. The isomerization dewaxing oil is then hydrosaturated to obtain high viscosity index lubricating oil base oil. This method can simultaneously produce petroleum wax and high viscosity index lubricating oil base oil, maximizing the overall yield of petroleum wax and base oil. The defects of this technology or the shortcomings of this invention are as follows: This patent uses solvent dewaxing, hydrotreating and isomerization dewaxing processes to separate petroleum wax from the feedstock oil, which is a dewaxing process and not a practical flexible production method. CN110607192A discloses a method for simultaneously producing low-oil-content wax and medium and high viscosity index base oils, wherein the method includes: (1) separating a fraction with a distillation range of not less than 350°C from hydrocracking tail oil; (2) under dewaxing conditions, contacting the fraction with a distillation range of not less than 350°C with a dewaxing solvent to perform solvent dewaxing, to obtain dewaxed oil and oil-containing wax paste; the dewaxed oil is used as a raw material for producing medium viscosity index base oil; (3) under deoiling conditions, contacting the oil-containing wax paste with a deoiling solvent to perform solvent deoiling, to obtain deoiled wax and wax residue; the deoiled wax is used as a raw material for producing petroleum wax; (4) subjecting the wax residue to hydroisomerization and hydrorefining to obtain high viscosity index base oil. The method provided by this invention can simultaneously produce low-oil-content wax and medium- and high-viscosity-index base oils; however, the defects of this technology or its shortcomings relative to this invention are as follows: this patent uses solvent dewaxing, hydrotreating and isomerization dewaxing processes to separate petroleum wax from the feedstock oil, which is a dewaxing process and not a practical flexible production method. Summary of the Invention

[0004] To address the aforementioned technical problems, the present invention aims to provide a method for producing polyethylene wax based on a nickel metal catalyst, and a method for flexibly switching between producing highly branched polyethylene oil and narrow molecular weight polyethylene wax.

[0005] To achieve the above objectives, the present invention provides a method for producing polyethylene wax based on a nickel metal catalyst, comprising: fully contacting ethylene with a nickel metal catalyst to induce a polymerization reaction of ethylene, thereby obtaining polyethylene wax;

[0006] The nickel metal catalyst comprises a main catalyst and a co-catalyst in a molar ratio of 1:100-1000. The co-catalyst is an alkylaluminum, and the main catalyst is a bidentate azahexane nickel complex having the structure shown in formula (I):

[0007]

[0008] R1 and R2 may be the same or different, and each is independently selected from substituted or unsubstituted C1-C. 10 Alkyl, C1-C 10 Alkoxy, C2-C 10 alkenyl or C6-C 10 Aryl;

[0009] R3 is selected from hydrogen, methyl, methoxy, and trifluoromethyl;

[0010] X is selected from chlorine or bromine.

[0011] According to a specific embodiment of the present invention, preferably, in the bidentate azirmonopolymer nickel complex, R1 and R2 are each independently selected from methyl, ethyl, propenyl or phenyl, more preferably methyl or ethyl.

[0012] According to a specific embodiment of the present invention, preferably, in the bidentate azirmonotriazine nickel complex, R3 is selected from methoxy or methyl.

[0013] According to a specific embodiment of the present invention, preferably, the bidentate azahexane nickel complex satisfies any one of the following conditions:

[0014] R1 and R2 are both methyl groups, R3 is hydrogen, and X is chlorine.

[0015] R1 and R2 are both methyl groups, R3 is methyl, and X is chlorine.

[0016] R1 and R2 are both methyl groups, R3 is methoxy group, and X is chlorine.

[0017] R1 and R2 are both methyl groups, R3 is trifluoromethyl, and X is chlorine.

[0018] R1 and R2 are both ethyl groups, R3 is hydrogen, and X is chlorine.

[0019] R1 and R2 are both ethyl groups, R3 is methyl, and X is chlorine.

[0020] R1 and R2 are both ethyl groups, R3 is methoxy, and X is chlorine.

[0021] R1 and R2 are both ethyl groups, R3 is trifluoromethyl, and X is chlorine.

[0022] R1 and R2 are both methyl groups, R3 is hydrogen, and X is bromine;

[0023] R1 and R2 are both methyl groups, R3 is methyl, and X is bromine.

[0024] The bidentate azahexane nickel complex of the present invention is prepared by the following method:

[0025] α-Bromoisobutyraldehyde and a dialkylamine of the general formula R1R2-NH are subjected to a substitution reaction to obtain amino-substituted isobutyraldehyde as shown in formula (II).

[0026] The amino-substituted isobutyraldehyde shown in formula (II) undergoes a condensation reaction with the arylnaphthylamine shown in formula (III) to obtain the azaligand shown in formula (IV);

[0027] The aza-ligand is subjected to a coordination reaction with NiX2 to obtain the bidentate aza-nickel complex.

[0028]

[0029] The molar ratio of amino-substituted isobutyraldehyde to arylnaphthylamine is 1:1.2-2, more preferably 1:1.5; the molar ratio of azaligand to NiX2 is 1-1.5:1, more preferably 1.2:1; the condensation reaction temperature is 80-150℃, and the reaction time is 6-48h.

[0030] The synthetic route for the bidentate azahexane nickel complex of the present invention is as follows:

[0031]

[0032] According to a specific embodiment of the present invention, preferably, the alkyl aluminum includes methylaluminoxane (MAO), modified methylaluminoxane (MMAO), diethylaluminum chloride (AlEt2Cl), diethylaluminum chloride (AlEtCl2), and more preferably methylaluminoxane and / or modified methylaluminoxane.

[0033] According to a specific embodiment of the present invention, preferably, the molar ratio of the main catalyst to the co-catalyst in the nickel metal catalyst is 1:800-1000. In the present invention, the molar ratio of the bidentate azahexa nickel complex to the alkyl aluminum is equivalent to the Al / Ni molar ratio in the nickel metal catalyst.

[0034] According to a specific embodiment of the present invention, preferably, the pressure of ethylene during the polymerization reaction is 10-50 atm, more preferably 30-40 atm.

[0035] According to a specific embodiment of the present invention, preferably, the polymerization temperature is 30-80°C, more preferably 50-75°C; and the polymerization time (residence time) is 0.5-8h.

[0036] According to a specific embodiment of the present invention, preferably, during the polymerization reaction, the nickel metal catalyst is dispersed in a solvent, wherein the solvent includes one or more of alkanes, aromatics, halogenated hydrocarbons, and olefins.

[0037] According to a specific embodiment of the present invention, preferably, the solvent includes one or more combinations of n-hexane, methylcyclohexane, cyclohexane, heptane, decane, benzene, toluene, xylene, cumene, 1-butene, 1-hexene, or 1-octene, more preferably toluene.

[0038] According to a specific embodiment of the present invention, preferably, the method for preparing polyethylene wax further includes: terminating the polymerization reaction with hydrochloric acid, and purifying the terminated reaction solution with acidic ethanol to obtain polyethylene wax.

[0039] This invention also provides a method for flexibly switching between the production of highly branched polyethylene oil and narrow-distribution low-molecular-weight polyethylene wax. This method includes adjusting the polymerization reaction temperature, ethylene pressure, and the ratio of the main catalyst to the co-catalyst in the nickel metal catalyst, based on the aforementioned method for producing polyethylene wax using a nickel metal catalyst. This method allows for flexible switching between the production of highly branched polyethylene oil and narrow-distribution low-molecular-weight polyethylene wax within a single unit.

[0040] The flexible switching method of this invention balances the reaction differences between ethylene polymerization to produce polyethylene oil and ethylene polymerization to produce polyethylene wax, ultimately enabling the production of two polyethylene products from a single reaction unit.

[0041] The technical solution provided by this invention has the following beneficial effects:

[0042] (1) The bidentate azide nickel complex used in this invention adopts a “one rigid and one flexible” and “one large and one small” design structure, which can ensure that the catalyst can be prepared with high activity under high pressure to produce low molecular weight polyethylene wax products with narrow distribution.

[0043] (2) The ethylene polymerization reaction to produce polyethylene oil in this invention accelerates the chain walking and chain transfer process compared with the α-diimine nickel catalyst system, greatly reduces the reaction residence time, and the product has the characteristics of high branching and low molecular weight.

[0044] (3) The ethylene polymerization reaction in this invention produces polyethylene wax, and the product has the characteristics of narrow distribution and low molecular weight. Detailed Implementation

[0045] In order to provide a clearer understanding of the technical features, objectives and beneficial effects of the present invention, the technical solution of the present invention will now be described in detail below, but it should not be construed as limiting the scope of implementation of the present invention.

[0046] This invention uses 10 bidentate aziridine nickel complexes with specific chemical structures (as shown in Formula I). ​​The 16 bidentate aziridine nickel complexes are named Ni1-Ni10, and the types of each group are as follows:

[0047] In the bidentate azametal nickel complex Ni1, R1 and R2 are both methyl groups, R3 is hydrogen, and X is chlorine.

[0048] The bidentate azahexane nickel complex Ni2 has R1 and R2 both being methyl, R3 being methyl, and X being chlorine;

[0049] The bidentate azametallic nickel complex Ni3 has R1 and R2 both being methyl groups, R3 being a methoxy group, and X being a chlorine group.

[0050] The bidentate azahexane nickel complex Ni4 has R1 and R2 both being methyl groups, R3 being trifluoromethyl, and X being chlorine.

[0051] The bidentate azirmonopolymer Ni5 has two ethyl groups (R1 and R2), one hydrogen group (R3), and one chlorine group (X).

[0052] The bidentate azahexane nickel complex Ni6 has R1 and R2 both being ethyl groups, R3 being a methyl group, and X being a chlorine group;

[0053] The bidentate azirmonopolymer Ni7 has two ethyl groups (R1 and R2), one methoxy group (R3), and one chlorine group (X).

[0054] The bidentate azahexane nickel complex Ni8 has R1 and R2 both being ethyl groups, R3 being trifluoromethyl, and X being chlorine.

[0055] The bidentate azametal nickel complex Ni9 has R1 and R2 both methyl, R3 hydrogen, and X bromine;

[0056] In the bidentate azirmonopolymer Ni10, R1 and R2 are both methyl groups, R3 is methyl, and X is bromine.

[0057] The aforementioned bidentate aziridine nickel complexes were synthesized from eight aziridines with specific chemical structures (as shown in Formula III) and NiCl2 or NiBr2. The eight aziridines were named L1-L8, and the types of each group are as follows:

[0058] Azaligands L1, R1, and R2 are all methyl groups, and R3 is hydrogen;

[0059] Azaligand L2, R1 and R2 are both methyl groups, and R3 is a methyl group;

[0060] The azaligand L3 has two methyl groups, R1 and R2, and R3 is methoxy.

[0061] The azaligand L4, R1 and R2 are both methyl groups, and R3 is a trifluoromethyl group;

[0062] The azaligand L5 has ethyl groups R1 and R2, and hydrogen R3.

[0063] In the azaligand L6, R1 and R2 are both ethyl groups, and R3 is a methyl group;

[0064] The azaligand L7 has ethyl groups R1 and R2, and methoxy groups R3.

[0065] The azaligand L8 has two ethyl groups, R1 and R2, and R3 is a trifluoromethyl group.

[0066] The above-mentioned azaligands were synthesized from two specific structures of amino-substituted isobutyraldehyde (as shown in general formula II) and four specific structures of arylnaphthylamine (as shown in general formula III). The two amino-substituted isobutyraldehydes were named B1 and B2, respectively, and the four arylnaphthylamines were named A1-A4, respectively. The types of each group are as follows:

[0067] Amino-substituted isobutyraldehyde B1, where R1 and R2 are both methyl groups;

[0068] Amino-substituted isobutyraldehyde B2, where R1 and R2 are both ethyl groups;

[0069] Arylnaphthylamine A1, R3 is hydrogen;

[0070] Arylnaphthylamine A2, R3 is methyl;

[0071] Arylnaphthylamine A3, where R3 is a methoxy group;

[0072] Arylnaphthylamine A4, R3 is trifluoromethyl.

[0073] The above-mentioned arylnaphthylamines A1-A4 can be prepared according to the method reported in the literature (Synthesis of Highly BranCHedPolyethylene Using “SandwiCH” (8-p-Tolyl naphthylα-diimine)nickel(II)Catalysts[J]. Organometallics 2013, 32(18), 5136-5143).

[0074] Example 1

[0075] This embodiment provides an amino-substituted isobutyraldehyde B1, the synthesis method of which is as follows:

[0076] At 0 °C, bromoisobutyraldehyde (4 g, 26 mmol) was placed in 30 mL of diethyl ether, and Me2NH (33 mL, 2 M in THF, 65 mmol) was added dropwise at 0 °C. The mixture was stirred for 4 h, and the ammonium salt was removed by filtration. The solvent was removed by rotary evaporation to obtain 2.60 g of yellow viscous liquid, with a yield of 86%.

[0077] 1H NMR (CDCl3, 400MHz) δ (ppm): 9.40 (s, 1H, CHO), 2.43 (s, 6H, N (CH3) 2), 1.05 (s, 6H, C (CH3) 2).

[0078] Example 2

[0079] This embodiment provides an amino-substituted isobutyraldehyde B2, the synthesis method of which differs from Example 1 only in that Et2NH is used instead of Me2NH; the rest is the same as in Example 1. The final product yielded 3.34 g, with a yield of 88%.

[0080] 1H NMR (CDCl3, 400MHz) δ (ppm): 9.39 (s, 1H, CHO), 2.50 (q, 4H, NCH2CH3), 1.07 (s, 6H, C (CH3) 2), 1.02 (t, 6H, NCH2CH3).

[0081] Example 3

[0082] This embodiment provides an aza-ligand L1, the synthesis method of which is as follows:

[0083] The amino-substituted isobutyraldehyde B1 (1 g, 8.7 mmol) and 8-phenyl-1-naphthylamine (A1) (2.87 g, 13.1 mmol) from Example 1 were placed in a 100 mL round-bottom flask with a side arm, 30 mL of toluene and 0.2 mL of formic acid were added, and the mixture was refluxed at 110 °C for 24 h. The mixture was then subjected to column chromatography with petroleum ether / ethyl acetate to obtain 2.1 g of off-white solid, which was the azaligand L1, with a yield of 75%.

[0084] 1H NMR (CDCl3, 400MHz) δ (ppm): 7.83 (dd, 1H, Ar-H), 7.72 (dd, 1H, Ar-H), 7.47 (s, 1H, CH=N), 7.45-7.39 (m ,2H,Ar-H),7.24-7.10(m,6H,Ar-H),6.68(dd,1H,Ar-H),2.17(s,6H,N(CH3)2),0.74(s,6H,C(CH3)2).

[0085] 13C NMR (CDCl3, 100MHz) δ (ppm): 168.85 (CH=N), 150.37, 142.10, 139.57, 135.52, 135.14, 130.20, 129.63, 129.12, 128.72, 128.02,128.53,127.85,126.27,126.05,125.73,60.69(C(CH3)2),39.16(N(CH3)2),21.11(Ar-CH3),18.48(C(CH3)2).

[0086] Example 4

[0087] This embodiment provides a nitrogen-containing ligand L2, the synthesis method of which differs from that of Example 3 only in that...

[0088] 8-Phenylo-1-naphthylamine (A1) was replaced with 8-p-tolyl-1-naphthylamine (A2), and the other conditions were the same as in Example 3; the azaligand L2 was finally obtained in 84% yield.

[0089] 1H NMR (CDCl3, 400MHz) δ (ppm): 7.83 (dd, 1H, Ar-H), 7.72 (dd, 1H, Ar-H), 7.47 (s, 1H, CH=N), 7.45-7.39 (m, 2H, Ar-H) ,7.24-7.12(m,5H,Ar-H),6.69(dd,1H,Ar-H),2.40(s,3H,Ar-CH3),2.17(s,6H,N(CH3)2),0.75(s,6H,C(CH3)2).

[0090] 13C NMR (CDCl3, 100MHz) δ (ppm): 168.84 (CH=N), 150.37, 142.10, 139.57, 135.52, 135.14, 130.20, 129.63, 129.12, 128.72, 128.02, 128.53,127.85,126.27,126.05,125.73,125.12,(Ar-C),60.69(C(CH3)2),39.16(N(CH3)2),21.11(Ar-CH3),18.48(C(CH3)2).

[0091] Example 5

[0092] This embodiment provides an azaligand L3, the only difference between which is the synthesis method and that of Example 3, except that 8-p-anisole-1-naphthylamine (A3) is used instead of 8-phenyl-1-naphthylamine (A1), and the other conditions are the same as in Example 3; the azaligand L3 is finally obtained with a yield of 80%.

[0093] 1H NMR (CDCl3, 400MHz) δ (ppm): 7.83 (dd, 1H, Ar-H), 7.72 (dd, 1H, Ar-H), 7.45 (s, 1H, CH=N), 7.45-7.39 (m, 2H, Ar-H), 7.24-7.12(m,5H,Ar-H),6.67(dd,1H,Ar-H),3.40(s,3H,Ar-OCH3),2.16(s,6H,N(CH3)2),0.72(s,6H,C(CH3)2).

[0094] 13C NMR (CDCl3, 100MHz) δ (ppm): 168.84 (CH=N), 150.37, 142.10, 139.57, 135.52, 135.14, 130.20, 129.63, 129.12, 128.72, 1 28.02,128.53,127.85,126.27,126.05,125.73,60.69(C(CH3)2),53.62(1C,O-CH3),39.16(N(CH3)2),18.48(C(CH3)2).

[0095] Example 6

[0096] This embodiment provides an azaligand L4, the only difference between which is the synthesis method and that of Example 3, except that 8-p-trifluorotolyl-1-naphthylamine (A4) is used instead of 8-phenyl-1-naphthylamine (A1), and the other conditions are the same as in Example 3; the azaligand L4 is finally obtained with a yield of 84%.

[0097] 1H NMR (CDCl3, 400MHz) δ (ppm): 7.85 (dd, 1H, Ar-H), 7.73 (dd, 1H, Ar-H), 7.47 (s, 1H, CH=N), 7 .45-7.32(m,7H,Ar-H),6.69(dd,1H,Ar-H),2.20(s,6H,N(CH3)2),0.76(s,6H,C(CH3)2).

[0098] 13C NMR (CDCl3, 100MHz) δ (ppm): 168.84 (CH=N), 150.37, 142.10, 139.57, 135.52, 135.14, 130.20, 129.63, 129.12, 128.72,128.02,128.53,127.85,126.27,126.05,125.73,61.69(C(CH3)2),39.16(N(CH3)2),18.48(C(CH3)2).

[0099] 19F NMR (CDCl3, 400MHz) δ (ppm): -60.60 (s, 3F, CF3).

[0100] Example 7

[0101] This embodiment provides an azaligand L5, the synthesis method of which differs from that of Example 3 only in that isobutyraldehyde B2 is replaced by an amino group instead of isobutyraldehyde B1, and the other conditions are the same as in Example 3; the azaligand L5 is finally obtained with a yield of 78%.

[0102] 1H NMR (CDCl3, 400MHz) δ (ppm): 7.81 (dd, 1H, Ar-H), 7.72 (dd, 1H, Ar-H), 7.47 (s, 1H, CH=N), 7.45-7.39 (m, 2H, Ar-H), 7.2 4-7.10(m,6H,Ar-H),6.68(dd,1H,Ar-H),2.12(q,4H,N(CH2CH3)2),0.75(s,6H,C(CH3)2),0.68(s,6H,N(CH2CH3)2).

[0103] 13C NMR (CDCl3, 100MHz) δ (ppm): 168.84 (CH=N), 150.37, 142.10, 139.57, 135.52, 135.14, 130.20, 129.63, 129.12, 128.72, 128.02 ,128.53,127.85,126.27,126.05,125.73,125.12,(Ar-C),63.0(C(CH3)2),43.8(NCH2CH3),21.8(C(CH3)2),15.8(NCH2CH3).

[0104] Example 8

[0105] This embodiment provides an azaligand L6, the synthesis method of which differs from that of Example 4 only in that isobutyraldehyde B2 is replaced by an amino group instead of isobutyraldehyde B1, and the other conditions are the same as in Example 4; the azaligand L6 is finally obtained with a yield of 82%.

[0106] 1H NMR (CDCl3, 400MHz) δ (ppm): 7.83 (dd, 1H, Ar-H), 7.72 (dd, 1H, Ar-H), 7.47 (s, 1H, CH=N), 7.45-7.39 (m, 2H, Ar-H), 7.24-7.12 (m, 5H,Ar-H),6.69(dd,1H,Ar-H),2.40(s,3H,Ar-CH3),2.11(q,4H,N(CH2CH3)2),0.72(s,6H,C(CH3)2),0.67(s,6H,N(CH2CH3)2).

[0107] 13C NMR (CDCl3, 100MHz) δ (ppm): 168.84 (CH=N), 150.37, 142.10, 139.57, 135.52, 135.14, 130.20, 129.63, 129.12, 128.72, 128.02, 128.53 ,127.85,126.27,126.05,125.73,125.12,(Ar-C),63.0(C(CH3)2),43.8(NCH2CH3),21.8(C(CH3)2),21.11(Ar-CH3),15.8(NCH2CH3).

[0108] Example 9

[0109] This embodiment provides an azaligand L7, the synthesis method of which differs from that of Example 5 only in that isobutyraldehyde B2 is replaced by an amino group instead of isobutyraldehyde B1, and the other conditions are the same as in Example 5; the azaligand L7 is finally obtained with a yield of 78%.

[0110] 1H NMR (CDCl3, 400MHz) δ (ppm): 7.83 (dd, 1H, Ar-H), 7.72 (dd, 1H, Ar-H), 7.45 (s, 1H, CH=N), 7.45-7.39 (m, 2H, Ar-H), 7.24-7.12 (m, 5H,Ar-H),6.67(dd,1H,Ar-H),3.40(s,3H,Ar-OCH3),2.09(q,4H,N(CH2CH3)2),0.72(s,6H,C(CH3)2),0.66(s,6H,N(CH2CH3)2).

[0111] 13C NMR (CDCl3, 100MHz) δ (ppm): 168.84 (CH=N), 150.37, 142.10, 139.57, 135.52, 135.14, 130.20, 129.63, 129.12, 128.72, 128.02, 128.53 ,127.85,126.27,126.05,125.73,125.12,(Ar-C),63.0(C(CH3)2),53.52(C,O-CH3),43.8(NCH2CH3),21.8(C(CH3)2),15.8(NCH2CH3).

[0112] Example 10

[0113] This embodiment provides an azaligand L8, the synthesis method of which differs from that of Example 6 only in that isobutyraldehyde B2 is replaced by an amino group instead of isobutyraldehyde B1, and the other conditions are the same as in Example 6; the azaligand L8 is finally obtained with a yield of 76%.

[0114] 1H NMR (CDCl3, 400MHz) δ (ppm): 7.85 (dd, 1H, Ar-H), 7.73 (dd, 1H, Ar-H), 7.47 (s, 1H, CH=N), 7.45-7.32 (m, 7 H,Ar-H),6.69(dd,1H,Ar-H),2.16(q,4H,N(CH2CH3)2),0.76(s,6H,C(CH3)2),0.70(s,6H,N(CH2CH3)2).

[0115] 13C NMR (CDCl3, 100MHz) δ (ppm): 169.63 (CH=N), 150.37, 142.10, 139.57, 135.52, 135.14, 130.20, 129.63, 129.12, 128.92, 128.02, 128.53 ,127.85,126.27,126.05,125.81,125.42,(Ar-C),63.0(C(CH3)2),53.52(C,O-CH3),43.9(NCH2CH3),21.9(C(CH3)2),15.7(NCH2CH3).

[0116] 19F NMR (CDCl3, 400MHz) δ (ppm): -60.70 (s, 3F, CF3).

[0117] Example 11

[0118] This embodiment provides a bidentate azahexane nickel complex Ni1, the synthesis method of which is as follows:

[0119] Under anhydrous and oxygen-free conditions, azaligand L1 (800 mg, 0.91 mmol) and (DME)NiCl2 (0.17 g, 0.75 mmol) were added to a Schlenk tube and reacted overnight in dichloromethane. The insoluble matter was removed by filtration, and the filtrate was evaporated under reduced pressure to about 5 mL of solvent remaining. Hexane was added to precipitate the precipitate, which was collected by filtration and washed three times with hexane. The solvent was then dried to obtain 0.45 g of purple powder, which is the bidentate azaligand nickel complex Ni1, with a yield of 80%.

[0120] MS(FAB,m / z):447.1(M++1).Anal.Calcd for C22H24Cl2N2Ni:C,59.24;H,5.42;Found:C,59.21;H,5.28.

[0121] ¹H NMR (CDCl₃, 400MHz) δ (ppm): 22.44 (s, Ar-H), 11.70 (br, Ar-H), 11.49 (br, Ar-H), 10.99 (dd, Ar-H), 8.05 (s, CH=N), 7.85 (m, Ar-H), 7.18–7.15 (m, Ar-H), 6.83 (d, Ar-H), 2.58 (s, N(CH₃)₂), 1.22 (s, C(CH₃)₂), -0.59 (s, N(CH₃)₂), -1.22 (s, C(CH₃)₂). Based on the integral ratio of N-CH₃, the ratio of the two isomers is 1.8:1.

[0122] Example 12

[0123] This embodiment provides a bidentate aziridine nickel complex Ni2, the only difference between which is the synthesis method and that of Example 11, except that aziridine L2 is used instead of aziridine L1, and the other conditions are the same as in Example 11; finally, a bidentate aziridine nickel complex Ni1 is obtained with a yield of 82%.

[0124] MS(FAB,m / z):461.2(M++1).Anal.Calcd for C23H26Cl2N2Ni:C,60.05;H,5.70;Found:C,60.03;H,5.72.

[0125] ¹H NMR (CDCl₃, 400MHz) δ (ppm): 22.46 (s, Ar-H), 11.70 (br, Ar-H), 11.49 (br, Ar-H), 10.99 (dd, Ar-H), 8.07 (s, CH=N), 7.85 (m, Ar-H), 7.18–7.15 (m, Ar-H), 6.83 (d, Ar-H), 3.26 (s, Ar-CH₃), 2.58 (s, N(CH₃)₂), 2.40 (s, Ar-CH₃), 1.22 (s, C(CH₃)₂), -0.54 (s, N(CH₃)₂), -1.23 (s, C(CH₃)₂). Based on the integral ratio of N-CH₃, the ratio of the two isomers is 2:1.

[0126] Example 13

[0127] This embodiment provides a bidentate aziridine nickel complex Ni3, the only difference between which is the synthesis method and that of Example 11, except that aziridine L3 is used instead of aziridine L1, and the other conditions are the same as in Example 11; finally, a bidentate aziridine nickel complex Ni3 is obtained with a yield of 80%.

[0128] MS(FAB,m / z):477.1(M++1).Anal.Calcd for C23H26Cl2N2NiO:C,58.03;H,5.51;Found:C,58.00;H,5.52.

[0129] ¹H NMR (CDCl₃, 400MHz) δ (ppm): 22.44 (s, Ar-H), 11.70 (br, Ar-H), 11.49 (br, Ar-H), 10.99 (dd, Ar-H), 8.07 (s, CH=N), 7.85 (m, Ar-H), 7.18–7.15 (m, Ar-H), 6.83 (d, Ar-H), 3.76 (s, -OCH₃), 3.40 (s, -OCH₃), 2.53 (s, N(CH₃)₂), 1.21 (s, C(CH₃)₂), -0.51 (s, N(CH₃)₂), -1.20 (s, C(CH₃)₂). Based on the integral ratio of N-CH₃, the ratio of the two isomers is 2.2:1.

[0130] Example 14

[0131] This embodiment provides a bidentate aziridine nickel complex Ni4, the only difference between which is the synthesis method and that of Example 11, except that aziridine L4 is used instead of aziridine L1, and the other conditions are the same as in Example 11;

[0132] The final product was a bidentate azide nickel complex Ni4, with a yield of 81%.

[0133] MS(FAB,m / z):515.1(M++1).Anal.Calcd for C23H23Cl2F3N2Ni:C,53.74;H,4.51;Found:C,53.75;H,4.50.

[0134] ¹H NMR (CDCl₃, 400MHz) δ (ppm): 22.49 (s, Ar-H), 11.90 (br, Ar-H), 11.79 (br, Ar-H), 10.99 (dd, Ar-H), 8.15 (s, CH=N), 7.85 (m, Ar-H), 7.18–7.15 (m, Ar-H), 6.83 (d, Ar-H), 3.26 (s, Ar-CH₃), 2.58 (s, N(CH₃)₂), 2.40 (s, Ar-CH₃), 1.20 (s, C(CH₃)₂), -0.52 (s, N(CH₃)₂), -1.18 (s, C(CH₃)₂). Based on the integral ratio of N-CH₃, the ratio of the two isomers is 2.3:1.

[0135] Example 15

[0136] This embodiment provides a bidentate aziridine nickel complex Ni5, the only difference between which is the synthesis method and that of Example 11, except that aziridine L5 is used instead of aziridine L1, and the other conditions are the same as in Example 11; the bidentate aziridine nickel complex Ni5 is finally obtained with a yield of 79%.

[0137] MS(FAB,m / z):475.1(M++1).Anal.Calcd for C24H28Cl2N2Ni:C,60.80;H,5.95;Found:C,60.83;H,5.98.

[0138] 1H NMR (CDCl3, 400MHz) δ (ppm): 8.07 (s, 1H, CH=N), 7.78 (dd, 1H, Ar-H), 7.70 (dd, 1H, Ar-H), 7.45-7.33 (m, 2H, Ar-H), 7.2 4-7.10(m,6H,Ar-H),6.68(dd,1H,Ar-H),2.16(q,4H,N(CH2CH3)2),0.71(s,6H,C(CH3)2),0.54(s,6H,N(CH2CH3)2).

[0139] Example 16

[0140] This embodiment provides a bidentate azeotropic nickel complex Ni6, the synthesis method of which differs from that of Example 11 only in that azeotropic ligand L6 is used instead of azeotropic ligand L1, while the other conditions are the same as in Example 11; finally, bidentate azeotropic nickel complex Ni6 is obtained with a yield of 85%. MS(FAB,m / z):489.1(M++1). Anal.Calcd for C25H30Cl2N2Ni:C,61.52;H,6.20;Found:C,61.51;H,6.21.

[0141] 1H NMR (CDCl3, 400MHz) δ (ppm): 8.02 (s, 1H, CH=N), 7.84 (dd, 1H, Ar-H), 7.72 (dd, 1H, Ar-H), 7.40-7.33 (m, 2H, Ar-H), 7.24-7.12 (m, 5H,Ar-H), 6.66(dd,1H,Ar-H), 2.40(s,3H,Ar-CH3), 2.11(q,4H,N(CH2CH3)2), 0.72(s,6H,C(CH3)2), 0.59(s,6H,N(CH2CH3)2).

[0142] Example 17

[0143] This embodiment provides a bidentate aziridine nickel complex Ni7, the only difference between which is the synthesis method and that of Example 11, except that aziridine L7 is used instead of aziridine L1, and the other conditions are the same as in Example 11; finally, the bidentate aziridine nickel complex Ni7 is obtained with a yield of 83%.

[0144] MS (FAB, m / z): 504.1 (M++1). Anal. Calcd for C25H27Cl2N2NiO: C, 59.56; H, 6.00; Found: C, 59.52; H, 5.98.

[0145] 1H NMR (CDCl3, 400MHz) δ (ppm): 8.02 (s, 1H, CH=N), 7.87 (dd, 1H, Ar-H), 7.72 (dd, 1H, Ar-H), 7.41-7.31 (m, 2H, Ar-H), 7.29-7.22 (m, 5H,Ar-H), 6.77(dd,1H,Ar-H), 3.37(s,3H,Ar-OCH3), 2.05(q,4H,N(CH2CH3)2), 0.68(s,6H,C(CH3)2), 0.60(s,6H,N(CH2CH3)2).

[0146] Example 18

[0147] This embodiment provides a bidentate aziridine nickel complex Ni8, the only difference between which is the synthesis method and that of Example 11, except that aziridine L8 is used instead of aziridine L1, and the other conditions are the same as in Example 11; finally, the bidentate aziridine nickel complex Ni8 is obtained with a yield of 83%.

[0148] MS(FAB,m / z):543.1(M++1).Anal.Calcd for C25H27Cl2F3N2Ni:C,55.39;H,5.02;Found:C,55.37;H,5.00.

[0149] 1H NMR (CDCl3, 400MHz) δ (ppm): 8.04 (s, 1H, CH=N), 7.80 (dd, 1H, Ar-H), 7.53 (dd, 1H, Ar-H), 7.35-7.22 (m, 7 H,Ar-H), 6.69(dd,1H,Ar-H), 2.09(q,4H,N(CH2CH3)2), 0.71(s,6H,C(CH3)2), 0.65(s,6H,N(CH2CH3)2).

[0150] Example 19

[0151] This embodiment provides a bidentate nitrided nickel complex Ni9, the only difference between which is the synthesis method and that of Example 11, except that (DME)NiBr2 is used instead of (DME)NiCl2, while the other conditions are the same as in Example 11; (DME)NiBr2 is used instead of (DME)NiCl2; finally, the bidentate nitrided nickel complex Ni9 is obtained with a yield of 81%.

[0152] MS(FAB,m / z):536.0(M++1).Anal.Calcd for C22H24Br2N2Ni:C,55.39;H,5.02;Found:C,49.40;H,4.52.

[0153] ¹H NMR (CDCl₃, 400MHz) δ (ppm): 22.44 (s, Ar-H), 11.70 (br, Ar-H), 11.49 (br, Ar-H), 10.99 (dd, Ar-H), 8.05 (s, CH=N), 7.85 (m, Ar-H), 7.18–7.15 (m, Ar-H), 6.83 (d, Ar-H), 2.58 (s, N(CH₃)₂), 1.20 (s, C(CH₃)₂), -0.56 (s, N(CH₃)₂), -1.24 (s, C(CH₃)₂). Based on the integral ratio of N-CH₃, the ratio of the two isomers is 2.1:1.

[0154] Example 20

[0155] This embodiment provides a bidentate nitrided nickel complex Ni10, the only difference between which is the synthesis method and that of Example 12, except that (DME)NiBr2 is used instead of (DME)NiCl2, and the other conditions are the same as in Example 12; finally, the bidentate nitrided nickel complex Ni10 is obtained with a yield of 86%.

[0156] MS(FAB,m / z):549.0(M++1).Anal.Calcd for C23H26BrN2Ni:C,50.32;H,4.77;Found:C,50.30;H,4.74.

[0157] ¹H NMR (CDCl₃, 400MHz) δ (ppm): 22.44 (s, Ar-H), 11.70 (br, Ar-H), 11.49 (br, Ar-H), 10.99 (dd, Ar-H), 8.05 (s, CH=N), 7.85 (m, Ar-H), 7.18–7.15 (m, Ar-H), 6.83 (d, Ar-H), 3.26 (s, Ar-CH₃), 2.58 (s, N(CH₃)₂), 2.40 (s, Ar-CH₃), 1.20 (s, C(CH₃)₂), -0.56 (s, N(CH₃)₂), -1.24 (s, C(CH₃)₂). Based on the integral ratio of N-CH₃, the ratio of the two isomers is 2.3:1.

[0158] In the following examples, the catalyst activity calculation formula is: Activity = Mass of polyethylene wax / (Molar amount of nickel catalyst × Time).

[0159] The molecular weight distribution and molecular weight of polyethylene wax were analyzed using high-temperature gel permeation chromatography (GPC).

[0160] Examples 21-30 below provide methods for preparing polyethylene wax using the above-mentioned bidentate azide nickel complexes Ni1-Ni16 as a catalyst.

[0161] Example 21

[0162] This embodiment provides a method for producing polyethylene wax based on a nickel metal catalyst, the specific steps of which are as follows:

[0163] The ethylene polymerization reaction was carried out in a stainless steel high-temperature and high-pressure reactor equipped with a stirring device. Before the polymerization reaction, the reactor was vacuum dried at 200°C for more than 2 hours. After the reactor cooled to room temperature, a toluene solution containing a co-catalyst was sequentially injected through the feed valve. Ethylene gas was introduced, and the reaction system was heated to the set polymerization temperature. The mixture was stirred thoroughly for 10 minutes, and a toluene solution containing a nickel complex was added through the feed valve. The ethylene pressure was increased to the set pressure and kept constant throughout the polymerization process. After the polymerization reaction reached the set time, the ethylene supply was stopped, and the pressure was slowly released. The reactor was opened, and 5% hydrochloric acid was added to the reactor to terminate the reaction, resulting in a crude polyethylene wax product containing toluene. After repeated acid washing, water washing, and drying, polyethylene wax was obtained.

[0164] In this embodiment, the polymerization conditions include: the nickel complex is the aforementioned bidentate aziridine nickel complex Ni1, with an amount of 1 μmol; the co-catalyst is modified methylaluminoxane (MMAO), and the Al / Ni molar ratio in the nickel metal catalyst (bidentate aziridine nickel complex + MMAO) is 500; the ethylene pressure is 30 atm, the polymerization temperature is 50°C, the polymerization time is 30 minutes, and the solvent is 70 mL of toluene.

[0165] Example 22

[0166] This embodiment provides a method for producing polyethylene wax based on a nickel metal catalyst. The only difference between this method and Example 21 is that the nickel complex is a bidentate azirmonopolymer nickel complex Ni2, the polymerization temperature is 30°C, the ethylene pressure is 50 atm, and the Al / Ni molar ratio is 800. All other conditions are the same as in Example 21.

[0167] Example 23

[0168] This embodiment provides a method for producing polyethylene wax based on a nickel metal catalyst. The only difference between this method and Example 21 is that the nickel complex is a bidentate azirmonopolymer nickel complex Ni3, the polymerization temperature is 40°C, the ethylene pressure is 40 atm, the Al / Ni molar ratio is 1000, and the other conditions are the same as in Example 21.

[0169] Example 24

[0170] This embodiment provides a method for producing polyethylene wax based on a nickel metal catalyst. The only difference between this method and Example 21 is that the nickel complex is a bidentate azirmonopolymer nickel complex Ni4, the polymerization temperature is 60°C, the ethylene pressure is 30 atm, and the Al / Ni molar ratio is 1000. All other conditions are the same as in Example 21.

[0171] Example 25

[0172] This embodiment provides a method for producing polyethylene wax based on a nickel metal catalyst. The only difference between this method and Example 21 is that the nickel complex is a bidentate azirmonopolymer nickel complex Ni5, the polymerization temperature is 70°C, the ethylene pressure is 30 atm, and the Al / Ni molar ratio is 1000. All other conditions are the same as in Example 21.

[0173] Example 26

[0174] This embodiment provides a method for producing polyethylene wax based on a nickel metal catalyst. The only difference between this method and Example 21 is that the nickel complex is a bidentate azirmonopolymer nickel complex Ni6, the polymerization temperature is 80°C, the ethylene pressure is 30 atm, and the Al / Ni molar ratio is 800. All other conditions are the same as in Example 21.

[0175] Example 27

[0176] This embodiment provides a method for producing polyethylene wax based on a nickel metal catalyst. The only difference between this method and Example 21 is that the nickel complex is a bidentate azirmonopolymer nickel complex Ni7, the polymerization temperature is 50°C, the ethylene pressure is 35 atm, and the Al / Ni molar ratio is 100. All other conditions are the same as in Example 21.

[0177] Example 28

[0178] This embodiment provides a method for producing polyethylene wax based on a nickel metal catalyst. The only difference between this method and Example 21 is that the nickel complex is a bidentate azirmonopolymer nickel complex Ni8, the polymerization temperature is 50°C, the ethylene pressure is 40 atm, and the Al / Ni molar ratio is 300. All other conditions are the same as in Example 21.

[0179] Example 29

[0180] This embodiment provides a method for producing polyethylene wax based on a nickel metal catalyst. The only difference between this method and Example 21 is that the nickel complex is a bidentate azirmonopolymer nickel complex Ni9, the polymerization temperature is 55°C, the ethylene pressure is 40 atm, and the Al / Ni molar ratio is 800. All other conditions are the same as in Example 21.

[0181] Example 30

[0182] This embodiment provides a method for producing polyethylene wax based on a nickel metal catalyst. The only difference between this method and Example 21 is that the nickel complex is a bidentate azirmonopolymer nickel complex Ni10, the polymerization temperature is 75°C, the ethylene pressure is 30 atm, and the Al / Ni molar ratio is 500. All other conditions are the same as in Example 21.

[0183] Comparative Example 1

[0184] This comparative example provides a method for preparing polyethylene oil, which differs from Example 25 (Ni5) only in the nickel complex used; all other conditions are the same as in Example 25. The nickel complex used in this comparative example is an α-diimine nickel complex containing only one nitrogen (imine nitrogen) ligand, denoted as nickel complex Ni11, with the following structural formula:

[0185]

[0186] The α-diimine nickel complex Ni11 in this comparative example can be prepared according to the method reported in the literature (Synthesis of Highly BranCHedPolyethylene Using “SandwiCH” (8-p-Tolyl naphthylα-diimine)nickel(II)Catalysts[J]. Organometallics 2013,32(18),5136-5143).

[0187] The results of catalytic ethylene polymerization in Examples 21-30 and Comparative Example 1 are shown in Table 1.

[0188] Table 1. Results of ethylene polymerization catalyzed by the bidentate azahexane nickel complex Ni1-Ni11 under the same conditions.

[0189]

[0190] The results shown in Table 1 indicate that the method for producing polyethylene wax based on a nickel metal catalyst of the present invention has high catalytic activity, and the resulting polyethylene wax has a narrow molecular weight distribution and low molecular weight.

[0191] As shown in Comparative Example 1, the catalyst exhibits significantly lower catalytic activity, a wider molecular weight distribution, and a higher molecular weight compared to the structure protected in this invention. Low molecular weight polyethylene wax primarily replaces traditional paraffin wax in practical applications, but compared to paraffin wax, it possesses advantages such as a higher softening point and better high-temperature thermal stability. Therefore, low molecular weight polyethylene wax is widely used in various fields of chemical production. Furthermore, narrow-distribution polyethylene wax represents the future development direction of low molecular weight polyethylene wax, possessing substantial market potential and promising considerable future demand.

Claims

1. A method for producing polyethylene wax based on a nickel metal catalyst, comprising: Ethylene is polymerized by fully contacting it with a nickel metal catalyst to obtain polyethylene wax. The nickel metal catalyst comprises a main catalyst and a co-catalyst in a molar ratio of 1:100-1000. The co-catalyst is an alkylaluminum, and the main catalyst is a bidentate azahexane nickel complex having the structure shown in formula (I): R1 and R2 may be the same or different, and each is independently selected from substituted or unsubstituted C1-C. 10 Alkyl, C1-C 10 Alkoxy, C2-C 10 alkenyl or C6-C 10 Aryl; R3 is selected from hydrogen, methyl, methoxy, and trifluoromethyl; X is selected from chlorine or bromine.

2. The method for producing polyethylene wax based on a nickel metal catalyst according to claim 1, wherein, R1 and R2 are each independently selected from methyl, ethyl, propenyl or phenyl, preferably methyl or ethyl.

3. The method for producing polyethylene wax based on a nickel metal catalyst according to claim 1, wherein, R3 is selected from methoxy or methyl.

4. The method for producing polyethylene wax based on a nickel metal catalyst according to claim 1, wherein, Didentate nitrogen-hexaned nickel complexes satisfy any one of the following conditions: R1 and R2 are both methyl groups, R3 is hydrogen, and X is chlorine. R1 and R2 are both methyl groups, R3 is methyl, and X is chlorine. R1 and R2 are both methyl groups, R3 is methoxy group, and X is chlorine. R1 and R2 are both methyl groups, R3 is trifluoromethyl, and X is chlorine. R1 and R2 are both ethyl groups, R3 is hydrogen, and X is chlorine. R1 and R2 are both ethyl groups, R3 is methyl, and X is chlorine. R1 and R2 are both ethyl groups, R3 is methoxy, and X is chlorine. R1 and R2 are both ethyl groups, R3 is trifluoromethyl, and X is chlorine. R1 and R2 are both methyl groups, R3 is hydrogen, and X is bromine; R1 and R2 are both methyl groups, R3 is methyl, and X is bromine.

5. The method for producing polyethylene wax based on a nickel metal catalyst according to claim 1, wherein, The alkylaluminum includes methylaluminoxane, modified methylaluminoxane, diethylaluminum chloride, and diethylaluminum chloride.

6. The method for producing polyethylene wax based on a nickel metal catalyst according to claim 1, wherein, During the polymerization reaction, the pressure of ethylene is 10-50 atm.

7. The method for producing polyethylene wax based on a nickel metal catalyst according to claim 1, wherein, The polymerization temperature is 30-80℃; the polymerization time is 0.5-8h.

8. The method for producing polyethylene wax based on a nickel metal catalyst according to claim 1, wherein, During the polymerization reaction, the nickel metal catalyst is dispersed in a solvent, which includes one or more of alkanes, aromatics, halogenated hydrocarbons, and alkenes.

9. The method for producing polyethylene wax based on a nickel metal catalyst according to claim 1, wherein, The method for preparing polyethylene wax further includes: terminating the polymerization reaction with hydrochloric acid and purifying the terminated reaction solution with acidic ethanol to obtain polyethylene wax.

10. A method for flexibly switching between producing highly branched polyethylene oil and narrow molecular weight polyethylene wax, comprising adjusting the polymerization reaction temperature, ethylene pressure, and the ratio of the main catalyst and the co-catalyst in the nickel metal catalyst in the method for producing polyethylene wax based on a nickel metal catalyst as described in any one of claims 1-9.

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