CN1332949C - Olefine oligomerization catalyst, and its preparation method and use - Google Patents

Abstract

The present invention relates to an olefine oligomerization catalyst which has a structure expression of a formula (1), wherein in the formula (1), R1 and R2 are respectively selected from hydrogen or alkyl of C1 to C6; R3 is selected from hydrogen, or nitryl or-CF3; M is selected from Ni or Pd; X is selected from halogen. The catalyst has the advantages of simple synthesis and high yield, is matched with cocatalysts of alkylaluminium oxygen alkyl, or aluminum alkyl, or halogenation aluminium alkylor triphenylphosphine, etc. for olefine oligomerization reaction and has high catalytic activity.

Description

A kind of olefin oligomerization catalyst and its preparation method and application

technical field

The invention relates to an olefin oligomerization catalyst and its preparation method and application. Specifically, it is a bidentate coordinated nickel or palladium complex and its preparation method, and also relates to a method in which the complex is used as a catalyst for olefin oligomerization.

Background technique

The linear α-olefin products synthesized by the oligomerization of low-carbon olefins have high commercial value and are mainly used in olefin comonomers, plasticizers, detergents, surfactants and lubricants. The homogeneous catalysts currently used in industry use complexes containing P^O chelating ligands as catalysts, and the yield of linear α-olefins in oligomerization products can reach more than 99%.

The other two main catalysts for olefin oligomerization are α-diimine nickel, palladium catalysts and bisimine pyridinium iron, cobalt-based catalysts. Different products such as polymers and oligomers can be obtained by adjusting the size and electronic properties of substituted phenyl groups in α-diimine ligands or bis-imine pyridine ligands. Similarly, Ni, Pd, and Co of pyridineformaldehyde Schiff bases similar to α-diimine also have the ability to polymerize olefins, and the molecular weight of its products ranges from several hundred to tens of thousands, compared with α-diimine nickel and palladium catalysts It has low catalytic activity and low molecular weight.

USP5,932,670 discloses a pyridine-2-acyl imide nickel dihalide (2-pyridinecarboxaldimime nickel dihalide) complex, which contains two six-membered rings in the complex ligand, one of which is connected to the imine nitrogen atom Benzene ring, the other is an azabenzene ring (pyridine ring) connected to the carbon atom of the imino group. In addition, the carbon atom of the imino group can also be connected with a substituent R, and R is an alkyl group with 1 to 70 carbon atoms or aryl. The complex is used as the main catalyst for olefin oligomerization, and MAO is required as the cocatalyst. The oligomerization activity is low, and the oligomerization activity is only 10 ⁴ g·(molNi) ^-1 ·hr ^-1 under 1MPa pressure.

USP5,714,556 discloses a kind of olefin polymerization method, and this method dissolves the nickel compound of zero valence in the acid of general formula HX, and the nickel compound that it selects for use is the compound that has three or four coordination bonds, wherein at least one ligand is unstable and all ligands are neutral. X in the HX acid is BF ₄ ^- , PF ₆ ^- , BAF ^- , or SbF ₆ ^- .

Contents of the invention

The object of the present invention is to provide a bidentate coordination olefin oligomerization catalyst and a preparation method, the catalyst is simple to synthesize and has relatively high olefin oligomerization activity.

Another object of the present invention is to provide a process for the oligomerization of olefins using the above catalyst.

Olefin oligomerization catalyst provided by the invention has the structural expression of formula (I):

In formula (I), R ₁ and R ₂ are selected from hydrogen or C ₁ -C ₆ alkyl; R ₃ is selected from hydrogen, nitro or -CF ₃ , M is selected from Ni or Pd, and X is selected from halogen.

We have found that N-pyridylbenzamide ligand compounds can be obtained by reacting 2-aminopyridine derivatives with benzoyl chloride derivatives. The catalyst can be obtained by reacting the ligand with Ni or Pd halide at room temperature. The synthesis method of the catalyst is simple and effective, is beneficial to industrial production, and can be used in olefin oligomerization in combination with various cocatalysts, and the cocatalysts have wide sources and are easy to obtain.

Detailed ways

In the catalyst of the present invention, R ₁ and R ₂ are substituents on the pyridine ring, preferably hydrogen or C ₁ -C ₄ alkyl, more preferably hydrogen, methyl, ethyl, propyl or isopropyl. R ₃ is a substituent on the benzene ring, preferably hydrogen or nitro, and the substituent position is preferably 4. The metal atom M in the catalyst is preferably Ni, and X is preferably chlorine or bromine.

Preferred formula (I) compound has: {N-[2-(6-methylpyridyl)] benzamide} nickel dibromide, {N-[2-(4,6-lutyl) ]benzamide} nickel dibromide, {N-[2-(6-diethylpyridyl)]benzamide} nickel dibromide, {N-[2-(6-methylpyridyl) ]-4-nitrobenzamide} nickel dibromide, {N-[2-(4,6-dimethylpyridyl)]-4-nitrobenzamide} nickel dibromide; {N- [2-(6-methylpyridyl)]benzamide} palladium dibromide, {N-[2-(4,6-dimethylpyridyl)]benzamide} palladium dibromide, {N -[2-(6-Diethylpyridyl)]benzamido}dibromide, {N-[2-(6-methylpyridyl)]-4-nitrobenzamide}dibromide Palladium chloride, {N-[2-(4,6-2 dimethylpyridyl)]-4-nitrobenzamide} palladium dibromide; {N-[2-(6-methylpyridyl) ]benzamide} nickel dichloride, {N-[2-(4,6-lutylpyridyl)]benzamide} nickel dichloride, {N-[2-(6-diethylpyridine) base)] benzamido} nickel dichloride, {N-[2-(6-methylpyridyl)]-4-nitrobenzamide} nickel dichloride, {N-[2-(4 , 6-lutylpyridyl)]-4-nitrobenzamide} nickel dichloride.

The preparation method of catalyst provided by the invention comprises the steps:

(1) benzoyl chloride derivatives shown in formula (II) are dissolved in tetrahydrofuran to make a solution, 2-aminopyridine derivatives shown in formula (III) are dissolved in pyridine to make a solution, and then described tetrahydrofuran The solution is added to the pyridine solution, and the compound of formula (II) and formula (III) is fully reacted at 20-100°C in a molar ratio of 1-1.1:1, then washed with water, and the solvent is removed to obtain N-pyridylbenzamides A ligand compound, wherein R ₃ in the formula (II) is selected from hydrogen, nitro or -CF ₃ , and R ₁ and R ₂ in the formula (III) are respectively selected from hydrogen or an alkyl group of C ₁ to C ₆ ;

(2) In tetrahydrofuran medium, react N _- pyridylbenzamide ligands with MX ₂ or MX ₂ ·DME at a molar ratio of 1-1.2:1 at 20-100° C. From Ni or Pd, X is selected from halogen, DME is ethylene glycol dimethyl ether, after the reaction is completed, tetrahydrofuran is removed, and the obtained solid is dried.

The step (1) of the method is the synthesis of the ligand. During the synthesis, the benzoyl chloride derivative needs to be dissolved in tetrahydrofuran to make a solution. The concentration of the solution is preferably 0.8 to 1.2 mol/liter, and then the 2-aminopyridine derivative is added to the pyridine It is made into a solution, and its concentration is preferably 0.8-1.2 mol/liter. The ligand compound can be obtained by adding the pyridine solution into the tetrahydrofuran solution for full contact reaction. The preferred reaction temperature is 20-40°C, and the reaction time is 2-50 hours, preferably 2-14 hours.

When the ligand is synthesized, the benzoyl chloride derivative is easy to decompose, so its dosage should be slightly excessive. In the reaction, pyridine is both a solvent and an absorbent for generating acid. The amount should be at least equivalent to the number of moles of the benzoyl chloride derivative. After the reaction, the product is washed with water, then filtered, and the solid is dried at 40° C. under reduced pressure for 2 to 4 hours to obtain the N-pyridylbenzamide ligand compound.

The step (2) in the method is the process of preparing the catalyst by reacting the ligand compound with the metal halide or its adduct. Before the reaction, the ligand compound is dissolved in tetrahydrofuran to form a solution, and the concentration of the solution is preferably 0.1-0.15 mol/liter. Then add the solution of the ligand compound into the prepared tetrahydrofuran solution of the metal halide or its adduct, the concentration of the metal halide in the solution is preferably 0.01-0.05 mol/liter. The solution of the metal halide can also be added to the solution of the ligand compound for reaction. The reaction temperature is preferably 20-40°C, and the time is preferably 8-24 hours. During the reaction, the metal halide and the ligand compound basically react in an equimolar ratio. In order to take full advantage of the metal halide, the ligand compound should be in a slight excess relative to the metal halide.

The metal halide MX ₂ used in the above (2) step is preferably NiBr ₂ , NiCl ₂ , PdCl ₂ , and it is best to react with the adduct MX ₂ ·DME of ethylene glycol dimethyl ether. The preparation method of the adduct is to fully react the metal halide MX ₂ in ethylene glycol dimethyl ether at 20-40° C., then remove the solvent, and dry the solid at 40-60° C. to obtain the adduct.

The method for carrying out olefin oligomerization with the catalyst of the present invention comprises: the compound represented by formula (I) is used as the main catalyst, and the phosphorus compound of alkylaluminoxane, alkylaluminum, alkylaluminum halide or general formula is PR ₃ ' As a co-catalyst, the oligomerization reaction of olefins is carried out at 10-100°C, preferably 30-80°C, and 0.1-5.0MPa. In the formula _PR'3 , R' is an alkyl group of C ₁ -C ₈ or C ₆ to C ₈ aryl group, the molar ratio of aluminum in the cocatalyst to the main catalyst is 100 to 2000:1 during the reaction, and the molar ratio of the cocatalyst _PR'3 to the main catalyst is 0.5 to 10:1.

The alkylalumoxane is selected from methylalumoxane, which can be linear or cyclic. Alkyl aluminum is selected from trimethylaluminum, triethylaluminum, triisobutylaluminum or monochlorodiethylaluminum, PR ₃ ' is selected from trimethylphosphorus, triethylphosphorus, triphenylphosphine or mesitylene base phosphorus.

The catalyst of the present invention is suitable for the oligomerization reaction of low-carbon olefins to synthesize linear alpha-olefins, and the preferred low-carbon olefins are ethylene, propylene, butene or hexene.

The present invention will be further described in detail below by examples, but the present invention is not limited thereto.

Example 1

Preparation of catalyst {N-[2-(6-methylpyridyl)]benzamide}nickel dibromide of the present invention.

(1) Preparation of ligand N-[2-(6-methylpyridyl)]benzamide

1.41 g of benzoyl chloride (10 mmol) was dissolved in tetrahydrofuran to form a solution of 10 ml, and this solution was added dropwise to 1.08 g of 2-amino-6-methylpyridine (10 mmol) in 10 ml at 20°C. ml of pyridine solution. React at 25°C for 12 hours, add 400 ml of deionized water to shake and wash to terminate the reaction, filter the washed material, and dry the filtered solid for 4 hours under reduced pressure to obtain 2.05 g of white solid, which is ligand a: N- [2-(6-Methylpyridyl)]benzamide, yield 99% by mass. The analysis results of the ligand are as follows:

FT-IR (KBr disc, cm ^-1 ): 3192(m), 1677(s), 1577(s), 1459(s), 1304(s), 1129(m), 790(m), 719(m ).

¹ H NMR (300 MHz, CDCl ₃ /ppm): 2.47 (s, 3H, CH ₃ ), 6.92-8.22 (m, 8H, ArH), 8.62 (s, 1H, NH).

Elemental analysis, measured (calculated) value, mass %: C, 73.77 (73.56); H, 5.73 (5.70); N, 12.98 (13.20).

(2) Preparation of NiBr ₂ ·DME adduct

5 g of _NiBr2 was added to 25 ml of ethylene glycol dimethyl ether (Sweden, ACRS company), and the reaction was stirred overnight at room temperature. After filtration, the obtained solid was washed twice with 10 ml of dry hexane, and dried under vacuum at 40°C for 2 hours to obtain 7.01 g of golden yellow solid NiBr ₂ ·DME.

(3) Preparation of catalyst

0.24 g (1.1 mmol) of ligand a was formulated into 10 ml of tetrahydrofuran solution, and added to 60 ml of tetrahydrofuran solution containing 0.308 g (1 mmol) of NiBr ₂ ·DME. React at 25°C for 12 hours, remove the solvent by filtration, wash the solid product with 10 ml of tetrahydrofuran, and dry under reduced pressure at 40°C to obtain 0.36 g of a yellow solid, which is catalyst F: {N-[2-(6-methylpyridyl)]benzene Formamide} nickel dibromide, yield 83 mass %, analysis result is as follows:

FT-IR (KBr disc, cm ^-1 ): 3273(br), 1626(s), 1577(w), 1533(s), 1461(m), 1417(w), 1315(m), 1228(w ), 797(m), 706(s), 237(s), 111(m).

Elemental analysis, measured (calculated) value, mass %: C, 36.99 (36.25); H, 2.87 (2.81); N, 6.59 (6.50).

Example 2

Prepare ligand b according to example 1 (1) step method: N-[2-(4,6-lutidine base)] benzamide, the difference is to use 2-amino-4,6-lutidine The reaction was carried out instead of 2-amino-6-picoline to obtain 1.43 g of a white solid, yield 63% by mass. The analysis results of the ligand are as follows:

FT-IR (KBr disc, cm ^-1 ): 3183(w), 1676(s), 1614(m), 1567(s), 1421(s), 1282(s), 846(w), 706(s) ).

¹ HNMR (300MHz, CDCl ₃ /ppm): 2.37 (s, 3H, CH ₃ ), 2.43 (s, 3H, CH ₃ ), 6.78-7.94 (m, 7H, ArH), 8.05 (s, 1H, NH) .

Elemental analysis, measured (calculated) value, mass %: C, 74.43 (74.3 1); H, 6.24 (6.24); N, 12.17 (12.38).

Prepare catalyst by the method for example 1 (3) step, difference is to react with the ligand b of 1.1 millimoles, obtains orange-red powder 0.3 gram, is catalyst G: {N-[2-(4,6-dimethyl Base pyridyl)] benzamide} nickel dibromide, yield 68% by mass. The analysis results are as follows:

FT-IR (KBr disc, cm ^-1 ): 3243(br), 1629(s), 1575(s), 1530(s), 1459(s), 1310(m), 847(m), 706(s) ), 231(s), 95(m).

Elemental analysis, measured (calculated) value, mass %: C, 37.57 (37.81); H, 3.16 (3.17); N, 6.18 (6.30).

Example 3

Prepare ligand c by the method of example 1 (1) step: N-[2-(6-diethylpyridyl)] benzamide, the difference is to replace 2- with 2-amino-6-diethylpyridine Amino-6-picoline was reacted to obtain 1.76 g of a white solid, with a yield of 78% by mass. The results of the ligand analysis were:

FT-IR (KBr disc, cm ^-1 ): 3280(m), 1652(s), 1601(m), 1538(m), 1449(s), 1308(s), 812(s), 714(s) ).

¹ HNMR (300MHz, CDCl ₃ /ppm): 1.34 (t, 3H, CH ₃ ), 2.78 (dd, 2H, CH ₂ ), 6.98-8.26 (m, 8H, ArH), 8.65 (s, 1H, NH) .

Elemental analysis, measured (calculated) value, mass %: C, 74.32 (74.31); H, 6.22 (6.24); N, 12.34 (12.38).

Prepare catalyst by the method for example 1 (3) step, difference is to react with the ligand c of 1.1 millimoles, obtains yellow powder 0.32 gram, is catalyst H: {N-[2-(6-diethylpyridyl )] benzamido} nickel dibromide, yield 72% by mass. The analysis results are as follows:

FT-IR (KBr disc, cm ^-1 ): 3369(br), 1624(s), 1578(w), 1534(m), 1456(s), 810(w), 700(m), 185(s ).

Elemental analysis, measured (calculated) value, mass %: C, 37.577 (37.81); H, 3.23 (3.17); N, 6.01 (6.30).

Example 4

Prepare ligand d by the method of example 1 (1) step: N-[2-(6-picoline)]-4-nitrobenzamide, the difference is to replace benzene with 4-nitrobenzoyl chloride Formyl chloride was reacted to obtain 2.5 g of a white solid, with a yield of 97% by mass. The analysis result is:

FT-IR (KBr disc, cm ^-1 ): 3343(m), 1653(s), 1602(s), 1528(s), 1453(s), 1349(m), 854(m), 791(m ), 716(m).

¹ H NMR (300 MHz, CDCl ₃ /ppm): 2.49 (s, 3H, CH ₃ ), 6.98-8.37 (m, 7H, ArH), 8.58 (s, 1H, NH).

Elemental analysis, measured (calculated) value, mass %: C, 60.02 (60.70); H, 4.24 (4.31); N, 15.95 (16.33).

Prepare catalyst by the method for example 1 (3) step, difference is to react with the ligand d of 1.1 millimoles, obtains yellow powder 0.24 gram, is catalyst I: {N-[2-(6-methylpyridyl) ]-4-nitrobenzamide} nickel dibromide, yield 50% by mass. The analysis results are as follows:

FT-IR (KBr disc, cm ^-1 ): 3372(br), 1630(s), 1604(m), 1534(s), 1461(s), 1348(s), 850(m), 712(m ), 216(s), 118(m).

Elemental analysis, measured (calculated) value, mass %: C, 32.65 (32.82); H, 2.39 (2.33); N, 8.64. (8.83).

Example 5

Prepare ligand e by the method of example 1 (1) step: N-[2-(4,6-dimethylpyridyl)]-4-nitrobenzamide, the difference is to use 4-nitrobenzyl Acyl chloride was used instead of benzoyl chloride, and 2-amino-4,6-lutidine was used instead of 2-amino-6-picoline for the reaction to obtain 2.24 g of a white solid with a yield of 83% by mass. The results of the ligand analysis were:

FT-IR (KBr disc, cm ^-1 ): 3326(w), 1655(s), 1606(w), 1526(s), 1439(s), 1345(s), 1285(w), 849(m ), 716(m).

¹ HNMR (300MHz, CDCl ₃ /ppm): 2.38 (s, 3H, CH ₃ ), 2.43 (s, 3H, CH ₃ ), 6.83-8.36 (m, 6H, ArH), 8.57 (s, 1H, NH) .

Elemental analysis, measured (calculated) value, mass %: C, 61.59 (61.99); H, 4.80 (4.83); N, 15.49 (15.49).

Prepare catalyst by the method for example 1 (3) step, difference is to react with the ligand e of 1.1 millimoles, obtains yellow powder 0.33 gram, is catalyst J: {N-[2-(4,6-dimethyl Pyridyl)]-4-nitrobenzamide-}nickel dibromide, yield 68% by mass. The analysis results are as follows,

FT-IR (KBr disc, cm ^-1 ): 3386(br), 1636(s), 1530(s), 1446(m), 1345(s), 851(m), 711(m), 228(s ), 123(m).

Elemental analysis, measured (calculated) value, mass %: C, 34.31 (34.33); H, 2.78 (2.68); N, 8.40 (8.58).

Example 6

Catalyst K is prepared by the method of example 1, and difference is (2) step uses NiCl ₂ to replace NiBr ₂ react, obtain adduct NiCl ₂ DME, then make 1 millimolar NiCl by the method described in (3) step ₂ DME reacts with ligand a to obtain catalyst K: {N-[2-(6-methylpyridyl)]benzamide} nickel dichloride, the yield is 65% by mass, and the analysis results are as follows:

Elemental analysis, measured (calculated) value, mass %: C, 45.60 (45.67); H, 3.56 (3.53); N, 8.19 (8.20).

Example 7-12

The following examples carry out ethylene oligomerization using the catalyst of the present invention.

An appropriate amount of the catalyst of the present invention is added in a 250 ml reaction flask with a stirrer, filled with nitrogen for replacement 5 times, and fed with ethylene gas to keep the pressure at normal pressure. Add 50 ml of dry toluene, after ethylene is saturated in toluene, add an appropriate amount of 10% methylalumoxane (MAO) in toluene, react at 20°C for 1 hour, add 10 ml of acidified ethanol containing 30% HCl to terminate the polymerization reaction. 100 ml of deionized water was added, the organic phase was separated, and its composition was analyzed by chromatography-mass spectrometry and gas chromatography. Activity was calculated from mass flow count values. Catalyst used in each example, Al/Ni mol ratio and reaction result are shown in Table 1.

Examples 13-17

The following example examines the reaction performance of ethylene oligomerization when triphenylphosphine is used as a cocatalyst.

Carry out ethylene oligomerization by the method for example 7, used catalyst is H, and addition is 2 milligrams, difference is that triphenylphosphine (PPh ₃ ) is cocatalyst, each example PPh ₃ /Ni molar ratio and reaction result are shown in table 2.

Example 18

Carry out ethylene oligomerization by the method for example 7, used catalyst is H, and addition is 2 milligrams, and difference is that diethylaluminum chloride is cocatalyst, makes Al/Ni mol ratio be 500 during reaction. The catalyst activity is 2.5×10 ⁴ g(molNi) ^-1 ·atm ^-1 ·hr ^-1 , and the product distribution is: C ₄ ⁼ , 88% by mass, C ₆ ⁼ , 12% by mass.

Examples 19-24

Carry out ethylene oligomerization reaction with catalyst of the present invention by the method for example 7, difference is to change cocatalyst MAO consumption, investigate the impact of MAO consumption on each catalyst reaction performance, the catalytic activity of catalyst used in each example under different cocatalyst consumption is shown in the table 3.

Examples 25-30

Carry out ethylene oligomerization reaction with catalyst of the present invention by the method for example 7, keep reaction pressure be 0.1MPa, Al/Ni mol ratio 500, investigate the influence of oligomerization reaction temperature on each catalyst reaction performance, each example used catalyst at different temperatures The reactivity can be seen in Table 4.

Table 1

Instance number Catalyst Al/Ni, molar ratio Catalytic activity [×10 ⁴ g·(molNi) ^-1 ·atm ^-1 ·hr ^-1 ] Product ^{distribution1} (mass%) serial number Dosage, μmol C ₄ C ₆ 7 F 5 500 1.98 78 twenty two 8 G 5 500 1.29 91 9 9 H 5 500 3.28 84 16 10 I 5 500 2.97 88 12 11 J 5 500 1.89 81 19 12 K 5 500 1.93 79 twenty one

Note 1: Determination with toluene as internal standard.

Table 2

instance number PPh ₃ /Ni(mol/mol) Catalytic activity [×10 ⁴ g·(molNi) ^-1 ·atm ^-1 ·hr ^-1 ] Product ^{distribution1} (mass%) C ₄ C ₆ C ₈ 13 0.5 16.2 80 18 2 14 1 16.2 73 twenty three 4 15 2 13.3 66 32 2 16 3 25.8 70 28 2 17 10 9.67 88 11 1

Note 1: Determination with toluene as internal standard.

table 3

Instance number Catalyst number Al/Ni, mol/mol 100 300 500 1000 2000 19 F 0.5 1.1 1.9 1.29 1.28 20 G 1.4 1.3 1.26 1.24 0.46 twenty one H 3.75 3.9 3.25 4.8 2.9 twenty two I 1.7 2.9 2.8 2.82 1.9 twenty three J 0.9 1.3 1.8 2.0 1.7

Note: Catalytic activity unit: [×10 ⁴ g·(molNi) ^-1 ·atm ^-1 ·hr ^-1 ]

Table 4

Instance number Catalyst number Reaction temperature, ℃ 0 18 40 60 twenty four F 0.5 1.1 1.9 1.29 25 G 1.4 1.3 1.26 1.24 26 H 3.75 3.9 3.25 4.8 27 I 1.7 2.9 2.8 2.82 28 J 0.9 1.3 1.8 2.0

Note: Catalytic activity unit: [×10 ⁴ g·(molNi) ^-1 ·atm ^-1 ·hr ^-1 ]

Claims (9)

1, a kind of olefin oligomerization catalyst, has the structural expression of formula (I):

In formula (I), R ₁ and R ₂ are selected from hydrogen or C ₁ -C ₆ alkyl; R ₃ is selected from hydrogen, nitro or -CF ₃ , M is selected from Ni or Pd, and X is selected from halogen. 2. The catalyst according to claim 1, characterized in that R ₁ and R ₂ are respectively selected from hydrogen or C ₁ -C ₄ alkyl, M is Ni, and X is chlorine or bromine. 3. A method for preparing the catalyst as claimed in claim 1, comprising the steps of: (1) benzoyl chloride derivatives shown in formula (II) are dissolved in tetrahydrofuran to make a solution, 2-aminopyridine derivatives shown in formula (III) are dissolved in pyridine to make a solution, and then described tetrahydrofuran The solution is added to the pyridine solution, and the compound of formula (II) and formula (III) is fully reacted at 20-100°C in a molar ratio of 1-1.1:1, then washed with water, and the solvent is removed to obtain N-pyridylbenzamides A ligand compound, wherein R ₃ in the formula (II) is selected from hydrogen, nitro or -CF ₃ , and R ₁ and R ₂ in the formula (III) are respectively selected from hydrogen or an alkyl group of C ₁ to C ₆ ; (2) In tetrahydrofuran medium, react N _- pyridylbenzamide ligands with MX ₂ or MX ₂ ·DME at a molar ratio of 1-1.2:1 at 20-100° C. From Ni or Pd, X is selected from halogen, DME is ethylene glycol dimethyl ether, after the reaction is completed, tetrahydrofuran is removed, and the obtained solid is dried. 4. The method according to claim 3, characterized in that the concentration of the pyridine solution of the 2-aminopyridine derivatives in step (1) is 0.8 to 1.2 mol/liter, and the concentration of the tetrahydrofuran solution of the benzoyl chloride derivatives is 0.8 ~1.2 mol/L. 5. The method according to claim 3, characterized in that the reaction temperature in step (1) is 20-40°C, and the reaction time is 2-14 hours. 6. The method according to claim 3, characterized in that the reaction temperature in step (2) is 20-40°C, and the reaction time is 8-24 hours. 7. The method according to claim 3, characterized in that the MX ₂ in step (2) is NiBr ₂ or NiCl ₂ . 8. A method for olefin oligomerization, comprising using the compound shown in claim 1 as formula (I) as the main catalyst, and using alkylaluminoxane, alkylaluminum, alkylaluminum halide or general formula PR ₃ ' The compound is a cocatalyst, and the oligomerization reaction of olefins is carried out under the conditions of 10-100°C and 0.1-5.0 MPa. In the formula _PR'3 , R' is an alkyl group of C ₁ to C ₈ or an alkyl group of C ₆ to C ₈ Aryl group, during the reaction, the molar ratio of aluminum in the cocatalyst to the main catalyst is 100 to 2000:1, and the molar ratio of the cocatalyst _PR'3 to the main catalyst is 0.5 to 10:1. 9. The method according to claim 8, characterized in that the alkylaluminoxane is selected from methylalumoxane, and the alkylaluminum is selected from trimethylaluminum, triethylaluminum, triisobutyl Aluminum or diethylaluminum chloride, PR ₃ ' is selected from trimethylphosphorus, triethylphosphorus, triphenylphosphine or tricresylphosphine.