LIGAND BASED CHROMIUM CATALYST AND APPLICATION IN CATALYZING ETHYLENE OLIGOMERIZATION

Abstract

A ligand based chromium catalyst and application in catalyzing ethylene oligomerization are disclosed. The chromium catalyst is formed by a chromium compound and an organic ligand containing P and/or N. The substituents on N and P of the ligand can be replaced, whereby selective ethylene trimerization and tetramerization can be realized so as to produce 1-hexene and 1-octene at the same time.

Claims

1. A ligand based chromium catalyst, which has a general formula as follows: ##STR00017## wherein in above structure, X, Y, and Z represent one element of N and P respectively, R.sup.1, R.sup.2, R.sup.3, R.sup.4, and R.sup.5 represent one of H, linear or branched alkyl, heteroalkyl, cycloalkyl, heterocycloalkyl, substituted aryl and derivatives thereof respectively, B.sup.1 and B.sup.2 represent a structural system which can transmit an electronic induction or conjugative effect of a group respectively, and Ln represents a group which has a chemical bond with metal chromium; and wherein when X and Y both are N element, and Z is P element, B.sup.1 represents one methylene group or a plurality of methylene groups.

2. The chromium catalyst according to claim 1, wherein the chromium catalyst is formed by a chromium compound and an organic ligand containing P and/or N.

3. The chromium catalyst according to claim 1, wherein the R.sup.1, R.sup.2, R.sup.3, R.sup.4, and R.sup.5 groups, when being connected with nitrogen atom, are respectively one selected from a group consisting of H, C.sub.1-C.sub.10 linear or branched alkyl, heteroalkyl, cycloalkyl, alkenyl, allyl, and substituted phenyl; and wherein the R.sup.1, R.sup.2, R.sup.3, R.sup.4, and R.sup.5 groups, when being connected with phosphorus atom, are respectively one selected from a group consisting of C.sub.1-C.sub.10 linear or branched alkyl, substituted aryl, and derivatives thereof.

4. The chromium catalyst according to claim 3, wherein the R.sup.1, R.sup.2, R.sup.3, R.sup.4, and R.sup.5 groups, when being connected with nitrogen atom, are respectively one selected from a group consisting of H, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, cyclobutyl, cyclopentyl, cyclohexyl, 2-methylcyclohexyl, 2,6-dimethylcyclohexyl, adamantly, vinyl, allyl, phenyl, naphthyl, 2-methylphenyl, 2,4-6-trimethylphenyl, 3,5-dimethylphenyl, 3,5-dimethoxyphenyl, 3,5-di-tert-butylphenyl, 2-thienyl, 2-furanyl, 2-pyridyl, and 3-pyridyl; and wherein the R.sup.1, R.sup.2, R.sup.3, R.sup.4, and R.sup.5 groups, when being connected with phosphorus atom, are respectively one selected from a group consisting of methyl, ethyl, butyl, phenyl (which can be connected to be condensed nucleus compound), 2-methylphenyl, 4-methylphenyl, 3,5-dimethylphenyl, 2-methoxyphenyl, 4-methoxyphenyl, 3,5-dimethoxyphenyl, 4-tert-butylphenyl, 3,5-di-tert-butylphenyl, 2-nitrophenyl, 4-nitrophenyl, 4-cyanophenyl, 3,4-(methylenedioxy) phenyl, 4-benzoylphenyl, 4-ethoxycarbonylphenyl, 4-trifluoromethylphenyl, 1-naphthyl, 4,4-biphenyl, 3,5-di(phenyl) phenyl, 2-thienyl, 2-furanyl, 2-pyridyl, and 3-pyridyl.

5. The chromium catalyst according to claim 1, wherein the chromium comes from a chromium inorganic compound or a chromium organic compound; wherein the chromium inorganic compound is chromium dichloride or chromium trichloride; and wherein the chromium organic compound is one selected from a group consisting of chromium dichloride-tetrahydrofuran complex, chromium dichloride-toluene tetrahydrofuran complex, chromium trichloride-tetrahydrofuran complex, chromium dichloride-carbene complex, chromium trichloride-carbene complex, chromium acetylacetonate, chromium tris (2-ethylhexanoate), methyl chromium dichloride-tetrahydrofuran complex, triphenyl chromium-tetrahydrofuran complex, dimethyl chromium-carbene complex, diethyl chromium-carbene complex, diphenyl chromium-carbene complex, and carbonyl chromium.

6. The chromium catalyst according to claim 1, wherein the structural systems B.sup.1 and B.sup.2 which can transmit an electronic induction or conjugative effect of a group are respectively a double bond group containing 18 or less carbon atoms.

7. The chromium catalyst according to claim 1, which is included in a carrier.

8. An ethylene oligomerization method using a chromium catalyst, comprising performing ethylene oligomerization reaction in the presence of the chromium catalyst (NP-ligand based chromium catalyst), which chromium catalyst having a general formula as follows: ##STR00018## wherein in above structure, X, Y, and Z represent one element of N and P respectively, R.sup.1, R.sup.2, R.sup.3, R.sup.4, and R.sup.5 represent one of H, linear or branched alkyl, heteroalkyl, cycloalkyl, heterocycloalkyl, substituted aryl and derivatives thereof respectively, B.sup.1 and B.sup.2 represent a structural system which can transmit an electronic induction or conjugative effect of a group respectively, and Ln represents a group which has a chemical bond with metal chromium; and wherein when X and Y both are N element, and Z is P element, B.sup.1 represents one methylene group or a plurality of methylene groups.

9. The ethylene oligomerization method according to claim 8, wherein a reaction temperature ranges from 0 C. to 200 C., an ethylene pressure ranges from 0.1 MPa to 20 MPa, a reaction time ranges from 0.01 h to 200 h, and a concentration of the catalyst ranges from 0.001 mmol/L to 1000 mmol/L.

10. The ethylene oligomerization method according to claim 9, further comprising mixing the NP-ligand based chromium catalyst with a co-catalyst in an organic solvent medium, so that a mixture obtained therein contacts with olefin and oligomerization reaction is performed.

11. The ethylene oligomerization method according to claim 10, wherein a ratio of the NP-ligand based chromium catalyst to the co-catalyst ranges from 1:10 to 1:4000.

12. The ethylene oligomerization method according to claim 10, wherein the co-catalyst is at least one selected from a group consisting of alkyl aluminum compound, aluminoxane compound, and organic boron compound, preferably is at least one selected from a group consisting of triethylaluminum, triisobutylaluminum, tri-n-butylaluminium, tri-n-hexylaluminium, tri-n-octylaluminium, methylaluminoxane, ethylaluminoxane, isobutylaluminoxane and modified aluminoxane, methylaluminoxane loaded on silica gel, alkylaluminum halide, tris (pentafluorophenol) aluminum, tris (trifluoromethyl butanol) aluminum, triphenylmethyl-tetra (trifluoromethyl butanol) aluminum salts, tetrafluoroborate, ether tetrafluoroborate, epoxy borane, triethylborane, tris (pentafluorophenyl) borane, tetra (pentafluorophenyl) borate, tri-perfluoroaryl boranes, tetra-perfluoroaryl borate, tributyl borate, tetra (3,5-ditrifluoromethyl) phenyl borohydride salt, and tetra (3,5-ditrifluoromethyl) phenyl boron-sodium salts.

13. The ethylene oligomerization method according to claim 10, wherein the organic solvent is at least one selected from a group consisting of toluene, xylene, n-butane, n-pentane, cyclopentane, methyl cyclopentane, n-hexane, n-heptane, cyclohexane, methylcyclohexane, tetrahydrofuran, dichloromethane, dichloroethane, ethyl ether, and isopropyl ether.

14. The ethylene oligomerization method according to claim 8, wherein the oligomerization comprises selective trimerization and tetramerization of ethylene so as to obtain 1-hexene and 1-octene.

15. The ethylene oligomerization method according to claim 8, wherein the chromium catalyst is formed by a chromium compound and an organic ligand containing P and/or N.

16. The ethylene oligomerization method according to claim 8, wherein the R.sup.1, R.sup.2, R.sup.3, R.sup.4, and R.sup.5 groups, when being connected with nitrogen atom, are respectively one selected from a group consisting of H, C.sub.1-C.sub.10 linear or branched alkyl, heteroalkyl, cycloalkyl, alkenyl, allyl, and substituted phenyl; and wherein the R.sup.1, R.sup.2, R.sup.3, R.sup.4, and R.sup.5 groups, when being connected with phosphorus atom, are respectively one selected from a group consisting of C.sub.1-C.sub.10 linear or branched alkyl, substituted aryl, and derivatives thereof.

17. The ethylene oligomerization method according to claim 8, wherein the R.sup.1, R.sup.2, R.sup.3, R.sup.4, and R.sup.5 groups, when being connected with nitrogen atom, are respectively one selected from a group consisting of H, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, cyclobutyl, cyclopentyl, cyclohexyl, 2-methylcyclohexyl, 2,6-dimethylcyclohexyl, adamantly, vinyl, allyl, phenyl, naphthyl, 2-methylphenyl, 2,4-6-trimethylphenyl, 3,5-dimethylphenyl, 3,5-dimethoxyphenyl, 3,5-di-tert-butylphenyl, 2-thienyl, 2-furanyl, 2-pyridyl, and 3-pyridyl; and wherein the R.sup.1, R.sup.2, R.sup.3, R.sup.4, and R.sup.5 groups, when being connected with phosphorus atom, are respectively one selected from a group consisting of methyl, ethyl, butyl, phenyl (which can be connected to be condensed nucleus compound), 2-methylphenyl, 4-methylphenyl, 3,5-dimethylphenyl, 2-methoxyphenyl, 4-methoxyphenyl, 3,5-dimethoxyphenyl, 4-tert-butylphenyl, 3,5-di-tert-butylphenyl, 2-nitrophenyl, 4-nitrophenyl, 4-cyanophenyl, 3,4-(methylenedioxy) phenyl, 4-benzoylphenyl, 4-ethoxycarbonylphenyl, 4-trifluoromethylphenyl, 1-naphthyl, 4,4-biphenyl, 3,5-di(phenyl) phenyl, 2-thienyl, 2-furanyl, 2-pyridyl, and 3-pyridyl.

18. The ethylene oligomerization method according to claim 8, wherein the chromium comes from a chromium inorganic compound or a chromium organic compound; wherein the chromium inorganic compound is chromium dichloride or chromium trichloride; and wherein the chromium organic compound is one selected from a group consisting of chromium dichloride-tetrahydrofuran complex, chromium dichloride-toluene tetrahydrofuran complex, chromium trichloride-tetrahydrofuran complex, chromium dichloride-carbene complex, chromium trichloride-carbene complex, chromium acetylacetonate, chromium tris (2-ethylhexanoate), methyl chromium dichloride-tetrahydrofuran complex, triphenyl chromium-tetrahydrofuran complex, dimethyl chromium-carbene complex, diethyl chromium-carbene complex, diphenyl chromium-carbene complex, and carbonyl chromium.

19. The ethylene oligomerization method according to claim 8, wherein the structural systems B.sup.1 and B.sup.2, which transmit an electronic induction or conjugative effect of a group, are respectively a double bond group containing 18 or less carbon atoms.

20. The ethylene oligomerization method according to claim 8, wherein the catalyst is included in a carrier.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0029] FIG. 1 shows the gas chromatogram of the oligomerization product of Example 5; and

[0030] FIG. 2 shows the gas chromatogram of the oligomerization product of Example 7.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0031] The present disclosure will be illustrated in detail hereinafter with reference to the Examples. However, the present disclosure is not limited by the contents of the Examples disclosed herein.

Example 1

[0032] 1. A ligand is prepared.

[0033] O-diphenylphosphino-N-methylaniline (2.91 g, 10 mmol) and toluene (40 mL) are added into a Schlenk bottle (100 mL) in N.sub.2 atmosphere. The solution is cooled to 78 C., and an n-hexane solution containing 10 mmol of n-butyl lithium is added into the solution under stirring. The reaction proceeds until a temperature thereof reaches room temperature, and the solution is stirred for another 3 hours. The reaction solution is then cooled to 78 C., and a toluene solution containing 10 mmol of bis (2,4,6-trimethylphenyl)-bromopropyl phosphonium is added into the solution under stirring. The reaction proceeds until the temperature thereof reaches room temperature, and the solution is stirred for another 12 hours.

[0034] After completion of the reaction, insoluble substance, i.e., lithium bromide is removed through filtration. The residual solution is separated by a chromatographic column, and is eluted by n-hexane. All of the solution is collected, and all solvent is removed by a rotary evaporator so as to obtain a yellow solid product. A productivity of the product is 45%.

[0035] The elemental analysis results are shown as follows. Calculation values: N, 2.33; C, 79.84; H, 7.54. Measured values: N, 2.15; C, 79.89; H, 7.46.

[0036] 2. A ligand chromium compound is prepared.

[0037] The ligand (0.60 g, 1 mmol) prepared in step 1, chromium trichloride(THF).sub.3 (0.37 g, 1 mmol) and THF solvent (50 mL) are added into a Schlenk bottle (100 mL) in N.sub.2 atmosphere. The reaction liquid is stirred for 25 hours. The solvent is removed with reduced temperature. Crude product is washed by n-hexane for several times so as to obtain a dark green solid product. A productivity of the product is 91%, and a structure thereof is shown in formula (1) as follows:

##STR00002##

[0038] The elemental analysis results are shown as follows. Calculation values: N, 1.84; C, 63.21; H, 5.97. Measured values: N, 1.75; C, 63.30; H, 5.86.

[0039] 3. A catalyst formed by the NP-ligand chromium compound as shown in formula (1) and methylaluminoxane (MAO) is used in an ethylene oligomerization reaction, and a method is described as follows.

[0040] A high pressure reactor (300 mL) is pre-treated. That is, the reactor is dried by an electric drier and is installed. The reactor is evacuated for 2 hours under a temperature being 50 C. to form a vacuum therein. A fully dried ethylene gas with a certain pressure is pumped into the reactor after N.sub.2 replacement for three times, and then a temperature of the reactor drops to room temperature.

[0041] Toluene solvent (60 mL) and methylaluminoxane (MAO) (2.5 mL) as co-catalyst are added into the reactor in an ethylene atmosphere. After stirring for 5 minutes, a toluene solution (20 mL) containing 5 mol of the NP-ligand chromium compound as shown in formula (1) is added into the reactor. A temperature of the reactor is raised to 30 C. under stirring, and reaction proceeds for 30 minutes under ethylene pressure being 3.0 MPa. The reaction goes on until a predetermined time, the stirring stops, a supply of ethylene gas stops, and the temperature of the reactor is reduced to about 5 C. A pressure of the reactor is reduced slowly, and a product after reaction is poured to an ethanol solution acidified with hydrochloric acid with a concentration being 10%. Organic products are separated by adding 100 mL of water. Liquid products are dried by anhydrous sodium sulfate, and are qualitatively and quantitatively analyzed through GC-FID methods. Solid products are collected after filtration, and are dried in vacuum at 50 C. until a weight thereof reaches a constant weight, and the mass percentage content is calculated separately.

[0042] An activity of the catalyst can be obtained through gas chromatographic analysis and calculation, and the activity of the catalyst and product compositions are shown in Table 1.

Example 2

[0043] A reaction temperature is changed to be 40 C. from 30 C. in Example 1, and other operating conditions are not changed. The reaction results are shown in Table 1.

Example 3

[0044] A reaction temperature is changed to be 50 C. from 30 C. in Example 1, and other operating conditions are not changed. The reaction results are shown in Table 1.

Example 4

[0045] A reaction temperature is changed to be 60 C. from 30 C. in Example 1, and other operating conditions are not changed. The reaction results are shown in Table 1.

Example 5

[0046] A reaction temperature is changed to be 70 C. from 30 C. in Example 1, and other operating conditions are not changed. The reaction results are shown in Table 1, and a gas chromatogram of an oligomerization product thereof is shown in FIG. 1.

Example 6

[0047] A reaction pressure is changed to be 3.5 MPa from 3.0 MPa in Example 1, a reaction temperature is changed to be 50 C. from 30 C. in Example 1, and other operating conditions are not changed. The reaction results are shown in Table 1.

Example 7

[0048] A reaction pressure is changed to be 4.0 MPa from 3.0 MPa in Example 1, a reaction temperature is changed to be 50 C. from 30 C. in Example 1, and other operating conditions are not changed. The reaction results are shown in Table 1, and a gas chromatogram of an oligomerization product thereof is shown in FIG. 2.

Example 8

[0049] A reaction pressure is changed to be 4.5 MPa from 3.0 MPa in Example 1, a reaction temperature is changed to be 50 C. from 30 C. in Example 1, and other operating conditions are not changed. The reaction results are shown in Table 1.

Example 9

[0050] A catalyst formed by the NP-ligand prepared in step 1 of Example 1, chromium compound chromium trichloride(THF).sub.3, and methylaluminoxane (MAO) is used in an ethylene oligomerization reaction, and a method is described as follows.

[0051] A high pressure reactor (300 mL) is pre-treated. That is, the reactor is dried by an electric drier and is installed. The reactor is evacuated for 2 hours with a temperature being 50 C. to form a vacuum therein. A fully dried ethylene gas with a certain pressure is pumped into the reactor after N.sub.2 replacement for three times, and then a temperature of the reactor drops to room temperature.

[0052] A toluene solution (20 mL) containing 20 mol of NP-ligand prepared in step 1 of Example 1, a toluene suspension (20 mL) containing 20 mol of chromium trichloride(THF).sub.3, and toluene solvent (20 mL) are added into the reactor in sequence in an ethylene atmosphere. A temperature of the reactor is raised to 50 C., and the mixed solution is stirred for 5 minutes. Methylaluminoxane (MAO) (10 mL) as co-catalyst is then added into the reactor. Reaction proceeds for 30 minutes under stirring with ethylene pressure being 4.0 MPa. The reaction goes on until a predetermined time, the stirring stops, a supply of ethylene gas stops, and the temperature of the reactor is reduced to about 5 C. A pressure of the reactor is reduced slowly, and a product after reaction is poured to an ethanol solution acidified with hydrochloric acid with a concentration being 10%. Organic products are separated by adding 100 mL of water. Liquid products are dried by anhydrous sodium sulfate, and are qualitatively and quantitatively analyzed through GC-FID methods. Solid products are collected after filtration, and are dried in vacuum at 50 C. until a weight thereof reaches a constant weight, and the mass percentage content is calculated separately.

[0053] An activity of the catalyst can be obtained through gas chromatographic analysis and calculation, and the activity of the catalyst and product compositions are shown in Table 2.

Example 10

[0054] According to the present Example, chromium trichloride(THF).sub.3 in Example 9 is replaced to be chromium dichloride(THF).sub.2, and other operating conditions are not changed. The reaction results are shown in Table 2.

Example 11

[0055] According to the present Example, chromium trichloride(THF).sub.3 in Example 9 is replaced to be chromium acetylacetonate, i.e., Cr(acac).sub.3, and other operating conditions are not changed. The reaction results are shown in Table 2.

Example 12

[0056] According to the present Example, chromium trichloride(THF).sub.3 in Example 9 is replaced to be chromium tris (2-ethylhexanoate), i.e., Cr(EH).sub.3, and other operating conditions are not changed. The reaction results are shown in Table 2.

Example 13

[0057] According to the present Example, chromium trichloride(THF).sub.3 in Example 9 is replaced to be chromium dichloride(tolyl)(THF).sub.3, and other operating conditions are not changed. The reaction results are shown in Table 2.

Example 14

[0058] According to the present Example, chromium trichloride(THF).sub.3 in Example 9 is replaced to be chromium dichloride, and other operating conditions are not changed. The reaction results are shown in Table 2.

Example 15

[0059] According to the present Example, chromium trichloride(THF).sub.3 in Example 9 is replaced to be chromium trichloride, and other operating conditions are not changed. The reaction results are shown in Table 2.

Example 16

[0060] According to the present Example, chromium trichloride(THF).sub.3 in Example 9 is replaced to be CrMe.sub.2(:C).sub.2 (:C is a nitrogen heterocyclic carbene, and a molecular formula thereof is C[N(iPr)C(Me)].sub.2), and other operating conditions are not changed. The reaction results are shown in Table 2.

Example 17

[0061] According to the present Example, chromium trichloride(THF).sub.3 in Example 9 is replaced to be CrEt.sub.2(:C).sub.2 (:C is a nitrogen heterocyclic carbene, and a molecular formula thereof is C[N(iPr)C(Me)].sub.2), and other operating conditions are not changed. The reaction results are shown in Table 2.

Example 18

[0062] According to the present Example, chromium trichloride(THF).sub.3 in Example 9 is replaced to be CrPh.sub.2(:C).sub.2 (:C is a nitrogen heterocyclic carbene, and a molecular formula thereof is C[N(iPr)C(Me)].sub.2), and other operating conditions are not changed. The reaction results are shown in Table 2.

Example 19

[0063] According to the present Example, chromium trichloride(THF).sub.3 in Example 9 is replaced to be CrPh.sub.3(THF).sub.3, and other operating conditions are not changed. The reaction results are shown in Table 2.

Example 20

[0064] According to the present Example, chromium trichloride(THF).sub.3 in Example 9 is replaced to be Cr(CO).sub.6, and other operating conditions are not changed. The reaction results are shown in Table 2.

Example 21

[0065] According to the present Example, chromium trichloride(THF).sub.3 in Example 9 is replaced to be CrMeCl.sub.2(THF).sub.3, and other operating conditions are not changed. The reaction results are shown in Table 2.

Example 22

[0066] 1. A ligand is prepared.

[0067] O-(diphenylphosphino)aniline (2.77 g, 10 mmol) and toluene (40 mL) are added into a Schlenk bottle (100 mL) in N.sub.2 atmosphere. The solution is cooled to 78 C., and an n-hexane solution containing 10 mmol of n-butyl lithium is added into the solution under stirring. The reaction proceeds until a temperature thereof reaches room temperature, and the solution is stirred for another 3 hours. The reaction solution is then cooled to 78 C., and a toluene solution containing 10 mmol of bis (2,4,6-trimethylphenyl)-bromopropyl phosphonium is added into the solution under stirring. The reaction proceeds until the temperature thereof reaches room temperature, and the solution is stirred for another 12 hours.

[0068] After completion of the reaction, insoluble substance, i.e., lithium bromide is removed through filtration. The residual solution is separated by a chromatographic column, and is eluted by n-hexane. All of the solution is collected, and all solvent is removed by a rotary evaporator so as to obtain a light yellow solid product. A productivity of the product is 33%.

[0069] The elemental analysis results are shown as follows. Calculation values: N, 2.38; C, 79.70; H, 7.37. Measured values: N, 2.35; C, 79.78; H, 7.36.

[0070] 2. A ligand chromium compound is prepared.

[0071] The ligand (0.59 g, 1 mmol) prepared in step 1, chromium trichloride(THF).sub.3 (0.37 g, 1 mmol) and THF solvent (50 mL) are added into a Schlenk bottle (100 mL) in N.sub.2 atmosphere. The reaction liquid is stirred for 25 hours. The solvent is removed with reduced temperature. Crude product is washed by n-hexane for several times so as to obtain a dark green solid product. A productivity of the product is 93%, and a structure thereof is shown in formula (2) as follows:

##STR00003##

[0072] The elemental analysis results are shown as follows. Calculation values: N, 1.88; C, 62.78; H, 5.81. Measured values: N, 1.92; C, 62.89; H, 5.76.

[0073] 3. A catalyst formed by the NP-ligand chromium compound as shown in formula (2) and methylaluminoxane (MAO) is used in an ethylene oligomerization reaction, and a method is described as follows.

[0074] A high pressure reactor (300 mL) is pre-treated. That is, the reactor is dried by an electric drier and is installed. The reactor is evacuated for 2 hours under a temperature being 50 C. to form a vacuum therein. A fully dried ethylene gas with a certain pressure is pumped into the reactor after N.sub.2 replacement for three times, and then a temperature of the reactor drops to room temperature.

[0075] Toluene solvent (60 mL) and methylaluminoxane (MAO) (2.5 mL) as co-catalyst are added into the reactor in an ethylene atmosphere. After stirring for 5 minutes, a toluene solution (20 mL) containing 5 mol of the NP-ligand chromium compound as shown in formula (2) is added into the reactor. A temperature of the reactor is raised to 50 C. under stirring, and reaction proceeds for 30 minutes under ethylene pressure being 4.0 MPa. The reaction goes on until a predetermined time, the stirring stops, a supply of ethylene gas stops, and the temperature of the reactor is reduced to about 5 C. A pressure of the reactor is reduced slowly, and a product after reaction is poured to an ethanol solution acidified with hydrochloric acid with a concentration being 10%. Organic products are separated by adding 100 mL of water. Liquid products are dried by anhydrous sodium sulfate, and are qualitatively and quantitatively analyzed through GC-FID methods. Solid products are collected after filtration, and are dried in vacuum at 50 C. until a weight thereof reaches a constant weight, and the mass percentage content is calculated separately.

[0076] An activity of the catalyst can be obtained through gas chromatographic analysis and calculation, and the activity of the catalyst and product compositions are shown in Table 3.

Example 23

[0077] 1. A ligand is prepared.

[0078] O-diphenylphosphino-N-methylaniline (2.91 g, 10 mmol) and toluene (40 mL) are added into a Schlenk bottle (100 mL) in N.sub.2 atmosphere. The solution is cooled to 78 C., and an n-hexane solution containing 10 mmol of n-butyl lithium is added into the solution under stirring. The reaction proceeds until a temperature thereof reaches room temperature, and the solution is stirred for another 3 hours. The reaction solution is then cooled to 78 C., and a toluene solution containing 10 mmol of diphenyl-bromopropyl phosphonium is added into the solution under stirring. The reaction proceeds until the temperature thereof reaches room temperature, and the solution is stirred for another 12 hours.

[0079] After completion of the reaction, insoluble substance, i.e., lithium bromide is removed through filtration. The residual solution is separated by a chromatographic column, and is eluted by n-hexane. All of the solution is collected, and all solvent is removed by a rotary evaporator so as to obtain a light yellow solid product. A productivity of the product is 62%.

[0080] The elemental analysis results are shown as follows. Calculation values: N, 2.71; C, 78.90; H, 6.43. Measured values: N, 2.63; C, 78.89; H, 6.34.

[0081] 2. A ligand chromium compound is prepared.

[0082] The ligand (0.52 g, 1 mmol) prepared in step 1, chromium trichloride(THF).sub.3 (0.37 g, 1 mmol) and THF solvent (50 mL) are added into a Schlenk bottle (100 mL) in N.sub.2 atmosphere. The reaction liquid is stirred for 25 hours. The solvent is removed with reduced temperature. Crude product is washed by n-hexane for several times so as to obtain a dark green solid product. A productivity of the product is 90%, and a structure thereof is shown in formula (3) as follows:

##STR00004##

[0083] The elemental analysis results are shown as follows. Calculation values: N, 2.07; C, 60.41; H, 4.92. Measured values: N, 2.05; C, 60.59; H, 5.01.

[0084] 3. A catalyst formed by the NP-ligand chromium compound as shown in formula (3) and methylaluminoxane (MAO) is used in an ethylene oligomerization reaction, and a method is described as follows.

[0085] A high pressure reactor (300 mL) is pre-treated. That is, the reactor is dried by an electric drier and is installed. The reactor is evacuated for 2 hours under a temperature being 50 C. to form a vacuum therein. A fully dried ethylene gas with a certain pressure is pumped into the reactor after N.sub.2 replacement for three times, and then a temperature of the reactor drops to room temperature.

[0086] Toluene solvent (60 mL) and methylaluminoxane (MAO) (2.5 mL) as co-catalyst are added into the reactor in an ethylene atmosphere. After stirring for 5 minutes, a toluene solution (20 mL) containing 5 mol of the NP-ligand chromium compound as shown in formula (3) is added into the reactor. A temperature of the reactor is raised to 50 C. under stirring, and reaction proceeds for 30 minutes with ethylene pressure being 4.0 MPa. The reaction goes on until a predetermined time, the stirring stops, a supply of ethylene gas stops, and the temperature of the reactor is reduced to about 5 C. A pressure of the reactor is reduced slowly, and a product after reaction is poured to an ethanol solution acidified with hydrochloric acid with a concentration being 10%. Organic products are separated by adding 100 mL of water. Liquid products are dried by anhydrous sodium sulfate, and are qualitatively and quantitatively analyzed through GC-FID methods. Solid products are collected after filtration, and are dried in vacuum at 50 C. until a weight thereof reaches a constant weight, and the mass percentage content is calculated separately.

[0087] An activity of the catalyst can be obtained through gas chromatographic analysis and calculation, and the activity of the catalyst and product compositions are shown in Table 3.

Example 24

[0088] 1. A ligand is prepared.

[0089] O-(diphenylphosphino) aniline (2.77 g, 10 mmol) and toluene (40 mL) are added into a Schlenk bottle (100 mL) in N.sub.2 atmosphere. The solution is cooled to 78 C., and an n-hexane solution containing 10 mmol of n-butyl lithium is added into the solution under stirring. The reaction proceeds until a temperature thereof reaches room temperature, and the solution is stirred for another 3 hours. The reaction solution is then cooled to 78 C., and a toluene solution containing 10 mmol of diphenyl-bromopropyl phosphonium is added into the solution under stirring. The reaction proceeds until the temperature thereof reaches room temperature, and the solution is stirred for another 12 hours.

[0090] After completion of the reaction, insoluble substance, i.e., lithium bromide is removed through filtration. The residual solution is separated by a chromatographic column, and is eluted by n-hexane. All of the solution is collected, and all solvent is removed by a rotary evaporator so as to obtain a light yellow solid product. A productivity of the product is 43%.

[0091] The elemental analysis results are shown as follows. Calculation values: N, 2.78; C, 78.71; H, 6.21. Measured values: N, 2.73; C, 78.68; H, 6.16.

[0092] 2. A ligand chromium compound is prepared.

[0093] The ligand (0.51 g, 1 mmol) prepared in step 1, chromium trichloride(THF).sub.3 (0.37 g, 1 mmol) and THF solvent (50 mL) are added into a Schlenk bottle (100 mL) in N.sub.2 atmosphere. The reaction liquid is stirred for 25 hours. The solvent is removed with reduced temperature. Crude product is washed by n-hexane for several times so as to obtain a dark green solid product. A productivity of the product is 88%, and a structure thereof is shown in formula (4) as follows:

##STR00005##

[0094] The elemental analysis results are shown as follows. Calculation values: N, 2.12; C, 59.88; H, 4.72. Measured values: N, 2.15; C, 60.02; H, 4.66.

[0095] 3. A catalyst formed by the NP-ligand chromium compound as shown in formula (4) and methylaluminoxane (MAO) is used in an ethylene oligomerization reaction, and a method is described as follows.

[0096] A high pressure reactor (300 mL) is pre-treated. That is, the reactor is dried by an electric drier and is installed. The reactor is evacuated for 2 hours under a temperature being 50 C. to form a vacuum therein. A fully dried ethylene gas with a certain pressure is pumped into the reactor after N.sub.2 replacement for three times, and then a temperature of the reactor drops to room temperature.

[0097] Toluene solvent (60 mL) and methylaluminoxane (MAO) (2.5 mL) as co-catalyst are added into the reactor in an ethylene atmosphere. After stirring for 5 minutes, a toluene solution (20 mL) containing 5 mol of the NP-ligand chromium compound as shown in formula (4) is added into the reactor. A temperature of the reactor is raised to 50 C. under stirring, and reaction proceeds for 30 minutes under ethylene pressure being 4.0 MPa. The reaction goes on until a predetermined time, the stirring stops, a supply of ethylene gas stops, and the temperature of the reactor is reduced to about 5 C. A pressure of the reactor is reduced slowly, and a product after reaction is poured to an ethanol solution acidified with hydrochloric acid with a concentration being 10%. Organic products are separated by adding 100 mL of water. Liquid products are dried by anhydrous sodium sulfate, and are qualitatively and quantitatively analyzed through GC-FID methods. Solid products are collected after filtration, and are dried in vacuum at 50 C. until a weight thereof reaches a constant weight, and the mass percentage content is calculated separately.

[0098] An activity of the catalyst can be obtained through gas chromatographic analysis and calculation, and the activity of the catalyst and product compositions are shown in Table 3.

Example 25

[0099] 1. A ligand is prepared.

[0100] O-diphenylphosphino-N-methylaniline (2.91 g, 10 mmol) and toluene (40 mL) are added into a Schlenk bottle (100 mL) in N.sub.2 atmosphere. The solution is cooled to 78 C., and an n-hexane solution containing 10 mmol of n-butyl lithium is added into the solution under stirring. The reaction proceeds until a temperature thereof reaches room temperature, and the solution is stirred for another 3 hours. The reaction solution is then cooled to 78 C., and a toluene solution containing 10 mmol of dicyclohexyl-bromopropyl phosphonium is added into the solution under stirring. The reaction proceeds until the temperature thereof reaches room temperature, and the solution is stirred for another 12 hours.

[0101] After completion of the reaction, insoluble substance, i.e., lithium bromide is removed through filtration. The residual solution is separated by a chromatographic column, and is eluted by n-hexane. All of the solution is collected, and all solvent is removed by a rotary evaporator so as to obtain a light yellow solid product. A productivity of the product is 51%.

[0102] The elemental analysis results are shown as follows. Calculation values: N, 2.64; C, 77.10; H, 8.56. Measured values: N, 2.55; C, 77.15; H, 8.49.

[0103] 2. A ligand chromium compound is prepared.

[0104] The ligand (0.53 g, 1 mmol) prepared in step 1, chromium trichloride(THF).sub.3 (0.37 g, 1 mmol) and THF solvent (50 mL) are added into a Schlenk bottle (100 mL) in N.sub.2 atmosphere. The reaction liquid is stirred for 25 hours. The solvent is removed with reduced temperature. Crude product is washed by n-hexane for several times so as to obtain a dark green solid product. A productivity of the product is 90%, and a structure thereof is shown in formula (5) as follows:

##STR00006##

[0105] The elemental analysis results are shown as follows. Calculation values: N, 2.04; C, 59.35; H, 6.59. Measured values: N, 2.01; C, 58.89; H, 6.47.

[0106] 3. A catalyst formed by the NP-ligand chromium compound as shown in formula (5) and methylaluminoxane (MAO) is used in an ethylene oligomerization reaction, and a method is described as follows.

[0107] A high pressure reactor (300 mL) is pre-treated. That is, the reactor is dried by an electric drier and is installed. The reactor is evacuated for 2 hours under a temperature being 50 C. to form a vacuum therein. A fully dried ethylene gas with a certain pressure is pumped into the reactor after N.sub.2 replacement for three times, and then a temperature of the reactor drops to room temperature.

[0108] Toluene solvent (60 mL) and methylaluminoxane (MAO) (2.5 mL) as co-catalyst are added into the reactor in an ethylene atmosphere. After stirring for 5 minutes, a toluene solution (20 mL) containing 5 mol of the NP-ligand chromium compound as shown in formula (5) is added into the reactor. A temperature of the reactor is raised to 50 C. under stirring, and reaction proceeds for 30 minutes under ethylene pressure being 4.0 MPa. The reaction goes on until a predetermined time, the stirring stops, a supply of ethylene gas stops, and the temperature of the reactor is reduced to about 5 C. A pressure of the reactor is reduced slowly, and a product after reaction is poured to an ethanol solution acidified with hydrochloric acid with a concentration being 10%. Organic products are separated by adding 100 mL of water. Liquid products are dried by anhydrous sodium sulfate, and are qualitatively and quantitatively analyzed through GC-FID methods. Solid products are collected after filtration, and are dried in vacuum at 50 C. until a weight thereof reaches a constant weight, and the mass percentage content is calculated separately.

[0109] An activity of the catalyst can be obtained through gas chromatographic analysis and calculation, and the activity of the catalyst and product compositions are shown in Table 3.

Example 26

[0110] 1. A ligand is prepared.

[0111] O-(diphenylphosphino) aniline (2.77 g, 10 mmol) and toluene (40 mL) are added into a Schlenk bottle (100 mL) in N.sub.2 atmosphere. The solution is cooled to 78 C., and an n-hexane solution containing 10 mmol of n-butyl lithium is added into the solution under stirring. The reaction proceeds until a temperature thereof reaches room temperature, and the solution is stirred for another 3 hours. The reaction solution is then cooled to 78 C., and a toluene solution containing 10 mmol of dicyclohexyl-bromopropyl phosphonuim is added into the solution under stirring. The reaction proceeds until the temperature thereof reaches room temperature, and the solution is stirred for another 12 hours.

[0112] After completion of the reaction, insoluble substance, i.e., lithium bromide is removed through filtration. The residual solution is separated by a chromatographic column, and is eluted by n-hexane. All of the solution is collected, and all solvent is removed by a rotary evaporator so as to obtain a light yellow solid product. A productivity of the product is 22%.

[0113] The elemental analysis results are shown as follows. Calculation values: N, 2.71; C, 76.71; H, 8.50. Measured values: N, 2.65; C, 76.70; H, 8.46.

[0114] 2. A ligand chromium compound is prepared.

[0115] The ligand (0.51 g, 1 mmol) prepared in step 1, chromium trichloride(THF).sub.3 (0.37 g, 1 mmol) and THF solvent (50 mL) are added into a Schlenk bottle (100 mL) in N.sub.2 atmosphere. The reaction liquid is stirred for 25 hours. The solvent is removed with reduced temperature. Crude product is washed by n-hexane for several times so as to obtain a dark green solid product. A productivity of the product is 85%, and a structure thereof is shown in formula (6) as follows:

##STR00007##

[0116] The elemental analysis results are shown as follows. Calculation values: N, 2.08; C, 58.72; H, 6.57. Measured values: N, 2.15; C, 68.84; H, 6.43.

[0117] 3. A catalyst formed by the NP-ligand chromium compound as shown in formula (6) and methylaluminoxane (MAO) is used in an ethylene oligomerization reaction, and a method is described as follows.

[0118] A high pressure reactor (300 mL) is pre-treated. That is, the reactor is dried by an electric drier and is installed. The reactor is evacuated for 2 hours with a temperature being 50 C. to form a vacuum therein. A fully dried ethylene gas with a certain pressure is pumped into the reactor after N.sub.2 replacement for three times, and then a temperature of the reactor drops to room temperature.

[0119] Toluene solvent (60 mL) and methylaluminoxane (MAO) (2.5 mL) as co-catalyst are added into the reactor in an ethylene atmosphere. After stirring for 5 minutes, a toluene solution (20 mL) containing 5 mol of the NP-ligand chromium compound as shown in formula (6) is added into the reactor. A temperature of the reactor is raised to 50 C. under stirring, and reaction proceeds for 30 minutes under ethylene pressure being 4.0 MPa. The reaction goes on until a predetermined time, the stirring stops, a supply of ethylene gas stops, and the temperature of the reactor is reduced to about 5 C. A pressure of the reactor is reduced slowly, and a product after reaction is poured to an ethanol solution acidified with hydrochloric acid with a concentration being 10%. Organic products are separated by adding 100 mL of water. Liquid products are dried by anhydrous sodium sulfate, and are qualitatively and quantitatively analyzed through GC-FID methods. Solid products are collected after filtration, and are dried in vacuum at 50 C. until a weight thereof reaches a constant weight, and the mass percentage content is calculated separately.

[0120] An activity of the catalyst can be obtained through gas chromatographic analysis and calculation, and the activity of the catalyst and product compositions are shown in Table 3.

Example 27

[0121] In the present Example, a ligand and a ligand chromium compound can be prepared according to the method of Example 1.

[0122] A catalyst formed by an NP-ligand chromium compound as shown in formula (7) and methylaluminoxane (MAO) is used in an ethylene oligomerization reaction, and a method is described as follows.

##STR00008##

[0123] A high pressure reactor (300 mL) is pre-treated. That is, the reactor is dried by an electric drier and is installed. The reactor is evacuated for 2 hours under a temperature being 50 C. to form a vacuum therein. A fully dried ethylene gas with a certain pressure is pumped into the reactor after N2 replacement for three times, and then a temperature of the reactor drops to room temperature.

[0124] Toluene solvent (60 mL) and methylaluminoxane (MAO) (2.5 mL) as co-catalyst are added into the reactor in an ethylene atmosphere. After stirring for 5 minutes, a toluene solution (20 mL) containing 5 mol of the NP-ligand chromium compound as shown in formula (7) is added into the reactor. A temperature of the reactor is raised to 50 C. under stirring, and reaction proceeds for 30 minutes under ethylene pressure being 4.0 MPa. The reaction goes on until a predetermined time, the stirring stops, a supply of ethylene gas stops, and the temperature of the reactor is reduced to about 5 C. A pressure of the reactor is reduced slowly, and a product after reaction is poured to an ethanol solution acidified with hydrochloric acid with a concentration being 10%. Organic products are separated by adding 100 mL of water. Liquid products are dried by anhydrous sodium sulfate, and are qualitatively and quantitatively analyzed through GC-FID methods. Solid products are collected after filtration, and are dried in vacuum at 50 C. until a weight thereof reaches a constant weight, and the mass percentage content is calculated separately.

[0125] An activity of the catalyst can be obtained through gas chromatographic analysis and calculation, and the activity of the catalyst and product compositions are shown in Table 3.

Example 28

[0126] In the present Example, a ligand and a ligand chromium compound can be prepared according to the method of Example 1.

[0127] A catalyst formed by an NP-ligand chromium compound as shown in formula (8) and methylaluminoxane (MAO) is used in an ethylene oligomerization reaction, and a method is described as follows.

##STR00009##

[0128] A high pressure reactor (300 mL) is pre-treated. That is, the reactor is dried by an electric drier and is installed. The reactor is evacuated for 2 hours under a temperature being 50 C. to form a vacuum therein. A fully dried ethylene gas with a certain pressure is pumped into the reactor after N.sub.2 replacement for three times, and then a temperature of the reactor drops to room temperature.

[0129] Toluene solvent (60 mL) and methylaluminoxane (MAO) (2.5 mL) as co-catalyst are added into the reactor in an ethylene atmosphere. After stirring for 5 minutes, a toluene solution (20 mL) containing 5 mol of the NP-ligand chromium compound as shown in formula (8) is added into the reactor. A temperature of the reactor is raised to 50 C. under stirring, and reaction proceeds for 30 minutes under ethylene pressure being 4.0 MPa. The reaction goes on until a predetermined time, the stirring stops, a supply of ethylene gas stops, and the temperature of the reactor is reduced to about 5 C. A pressure of the reactor is reduced slowly, and a product after reaction is poured to an ethanol solution acidified with hydrochloric acid with a concentration being 10%. Organic products are separated by adding 100 mL of water. Liquid products are dried by anhydrous sodium sulfate, and are qualitatively and quantitatively analyzed through GC-FID methods. Solid products are collected after filtration, and are dried in vacuum at 50 C. until a weight thereof reaches a constant weight, and the mass percentage content is calculated separately.

[0130] An activity of the catalyst can be obtained through gas chromatographic analysis and calculation, and the activity of the catalyst and product compositions are shown in Table 3.

Example 29

[0131] In the present Example, a ligand and a ligand chromium compound can be prepared according to the method of Example 1.

[0132] A catalyst formed by an NP-ligand chromium compound as shown in formula (9) and methylaluminoxane (MAO) is used in an ethylene oligomerization reaction, and a method is described as follows.

##STR00010##

[0133] A high pressure reactor (300 mL) is pre-treated. That is, the reactor is dried by an electric drier and is installed. The reactor is evacuated for 2 hours under a temperature being 50 C. to form a vacuum therein. A fully dried ethylene gas with a certain pressure is pumped into the reactor after N.sub.2 replacement for three times, and then a temperature of the reactor drops to room temperature.

[0134] Toluene solvent (60 mL) and methylaluminoxane (MAO) (2.5 mL) as co-catalyst are added into the reactor in an ethylene atmosphere. After stirring for 5 minutes, a toluene solution (20 mL) containing 5 mol of the NP-ligand chromium compound as shown in formula (9) is added into the reactor. A temperature of the reactor is raised to 50 C. under stirring, and reaction proceeds for 30 minutes under ethylene pressure being 4.0 MPa. The reaction goes on until a predetermined time, the stirring stops, a supply of ethylene gas stops, and the temperature of the reactor is reduced to about 5 C. A pressure of the reactor is reduced slowly, and a product after reaction is poured to an ethanol solution acidified with hydrochloric acid with a concentration being 10%. Organic products are separated by adding 100 mL of water. Liquid products are dried by anhydrous sodium sulfate, and are qualitatively and quantitatively analyzed through GC-FID methods. Solid products are collected after filtration, and are dried in vacuum at 50 C. until a weight thereof reaches a constant weight, and the mass percentage content is calculated separately.

[0135] An activity of the catalyst can be obtained through gas chromatographic analysis and calculation, and the activity of the catalyst and product compositions are shown in Table 3.

Example 30

[0136] In the present Example, a ligand and a ligand chromium compound can be prepared according to the method of Example 1.

[0137] A catalyst formed by an NP-ligand chromium compound as shown in formula (10) and methylaluminoxane (MAO) is used in an ethylene oligomerization reaction, and a method is described as follows.

##STR00011##

[0138] A high pressure reactor (300 mL) is pre-treated. That is, the reactor is dried by an electric drier and is installed. The reactor is evacuated for 2 hours under a temperature being 50 C. to form a vacuum therein. A fully dried ethylene gas with a certain pressure is pumped into the reactor after N.sub.2 replacement for three times, and then a temperature of the reactor drops to room temperature.

[0139] Toluene solvent (60 mL) and methylaluminoxane (MAO) (2.5 mL) as co-catalyst are added into the reactor in an ethylene atmosphere. After stirring for 5 minutes, a toluene solution (20 mL) containing 5 mol of the NP-ligand chromium compound as shown in formula (10) is added into the reactor. A temperature of the reactor is raised to 50 C. under stirring, and reaction proceeds for 30 minutes under ethylene pressure being 4.0 MPa. The reaction goes on until a predetermined time, the stirring stops, a supply of ethylene gas stops, and the temperature of the reactor is reduced to about 5 C. A pressure of the reactor is reduced slowly, and a product after reaction is poured to an ethanol solution acidified with hydrochloric acid with a concentration being 10%. Organic products are separated by adding 100 mL of water. Liquid products are dried by anhydrous sodium sulfate, and are qualitatively and quantitatively analyzed through GC-FID methods. Solid products are collected after filtration, and are dried in vacuum at 50 C. until a weight thereof reaches a constant weight, and the mass percentage content is calculated separately.

[0140] An activity of the catalyst can be obtained through gas chromatographic analysis and calculation, and the activity of the catalyst and product compositions are shown in Table 3.

Example 31

[0141] 1. A ligand is prepared.

[0142] O-(diphenylphosphino)bromobenzene (20 mmol), N,N-dimethyl methylamine (50 mmol), N,N-dimethyl methanamide solvent (40 mL), and CuI catalyst (0.5 g) are added into a Schlenk bottle (100 mL) in N.sub.2 atmosphere. The mixed liquid is heated to 80 C. and kept for 12 hours at such a temperature.

[0143] After completion of the reaction, the liquid is cooled to room temperature. Insoluble substances are removed through filtration. The residual solution is separated by a chromatographic column, and is eluted by n-hexane. All solution is collected, and all solvent and volatile compositions are removed through a vacuum decompression method so as to obtain a white solid product. A productivity of the product is 31%.

[0144] The elemental analysis results are shown as follows. Calculation values: N, 8.38; C, 75.43; H, 6.93. Measured values: N, 8.35; C, 75.50; H, 6.95.

[0145] 2. A ligand chromium compound is prepared.

[0146] The ligand (0.33 g, 1 mmol) prepared in step 1, chromium trichloride(THF).sub.3 (0.37 g, 1 mmol) and THF solvent (50 mL) are added into a Schlenk bottle (100 mL) in N.sub.2 atmosphere. The reaction liquid is stirred for 25 hours. The solvent is removed with reduced temperature. Crude product is washed by n-hexane so as to obtain a dark green solid product. A productivity of the product is 80%, and a structure thereof is shown in formula (11) as follows:

##STR00012##

[0147] The elemental analysis results are shown as follows. Calculation values: N, 5.69; C, 51.19; H, 4.70. Measured values: N, 5.62; C, 51.41; H, 4.66.

[0148] 3. A catalyst formed by the NP-ligand chromium compound as shown in formula (11) and methylaluminoxane (MAO) is used in an ethylene oligomerization reaction, and a method is described as follows.

[0149] A high pressure reactor (300 mL) is pre-treated. That is, the reactor is dried by an electric drier and is installed. The reactor is evacuated for 2 hours under a temperature being 50 C. to form a vacuum therein. A fully dried ethylene gas with a certain pressure is pumped into the reactor after N.sub.2 replacement for three times, and then a temperature of the reactor drops to room temperature.

[0150] Toluene solvent (60 mL) and methylaluminoxane (MAO) (2.5 mL) as co-catalyst are added into the reactor in an ethylene atmosphere. After stirring for 5 minutes, a toluene solution (20 mL) containing 5 mol of the NP-ligand chromium compound as shown in formula (11) is added into the reactor. A temperature of the reactor is raised to 50 C. under stirring, and reaction proceeds for 30 minutes under ethylene pressure being 4.0 MPa. The reaction goes on until a predetermined time, the stirring stops, a supply of ethylene gas stops, and the temperature of the reactor is reduced to about 5 C. A pressure of the reactor is reduced slowly, and a product after reaction is poured to an ethanol solution acidified with hydrochloric acid with a concentration being 10%.

[0151] Organic products are separated by adding 100 mL of water. Liquid products are dried by anhydrous sodium sulfate, and are qualitatively and quantitatively analyzed through GC-FID methods. Solid products are collected after filtration, and are dried in vacuum at 50 C. until a weight thereof reaches a constant weight, and the mass percentage content is calculated separately.

[0152] An activity of the catalyst can be obtained through gas chromatographic analysis and calculation, and the activity of the catalyst and product compositions are shown in Table 3.

Example 32

[0153] 1. A ligand is prepared.

[0154] O-(diphenylphosphino)bromobenzene (20 mmol), N,N-dimethyl ethylamine (50 mmol), N,N-dimethyl methanamide solvent (40 mL), and CuI catalyst (0.5 g) are added into a Schlenk bottle (100 mL) in N.sub.2 atmosphere. The mixed liquid is heated to 80 C. and kept for 12 hours at such a temperature.

[0155] After completion of the reaction, the liquid is cooled to room temperature. Insoluble substances are removed through filtration. The residual solution is separated by a chromatographic column, and is eluted by n-hexane. All solution is collected, and all solvent and volatile compositions are removed through a vacuum decompression method so as to obtain a white solid product. A productivity of the product is 37%.

[0156] The elemental analysis results are shown as follows. Calculation values: N, 8.04; C, 75.84; H, 7.23. Measured values: N, 8.05; C, 75.69; H, 7.27.

[0157] 2. A ligand chromium compound is prepared.

[0158] The ligand (0.35 g, 1 mmol) prepared in step 1, chromium trichloride(THF).sub.3 (0.37 g, 1 mmol) and THF solvent (50 mL) are added into a Schlenk bottle (100 mL) in N.sub.2 atmosphere. The reaction liquid is stirred for 25 hours. The solvent is removed with reduced temperature. Crude product is washed by n-hexane so as to obtain a dark green solid product. A productivity of the product is 91%, and a structure thereof is shown in formula (12) as follows:

##STR00013##

[0159] The elemental analysis results are shown as follows. Calculation values: N, 5.53; C, 52.14; H, 4.97. Measured values: N, 5.65; C, 52.12; H, 4.76.

[0160] 3. A catalyst formed by the NP-ligand chromium compound as shown in formula (12) and methylaluminoxane (MAO) is used in an ethylene oligomerization reaction, and a method is described as follows.

[0161] A high pressure reactor (300 mL) is pre-treated. That is, the reactor is dried by an electric drier and is installed. The reactor is evacuated for 2 hours with a temperature being 50 C. to form a vacuum therein. A fully dried ethylene gas with a certain pressure is pumped into the reactor after N.sub.2 replacement for three times, and then a temperature of the reactor drops to room temperature.

[0162] Toluene solvent (60 mL) and methylaluminoxane (MAO) (2.5 mL) as co-catalyst are added into the reactor in an ethylene atmosphere. After stirring for 5 minutes, a toluene solution (20 mL) containing 5 mol of the NP-ligand chromium compound as shown in formula (12) is added into the reactor. A temperature of the reactor is raised to 50 C. under stirring, and reaction proceeds for 30 minutes under ethylene pressure being 4.0 MPa. The reaction goes on until a predetermined time, the stirring stops, a supply of ethylene gas stops, and the temperature of the reactor is reduced to about 5 C. A pressure of the reactor is reduced slowly, and a product after reaction is poured to an ethanol solution acidified with hydrochloric acid with a concentration being 10%. Organic products are separated by adding 100 mL of water. Liquid products are dried by anhydrous sodium sulfate, and are qualitatively and quantitatively analyzed through GC-FID methods. Solid products are collected after filtration, and are dried in vacuum at 50 C. until a weight thereof reaches a constant weight, and the mass percentage content is calculated separately.

[0163] An activity of the catalyst can be obtained through gas chromatographic analysis and calculation, and the activity of the catalyst and product compositions are shown in Table 3.

Example 33

[0164] 1. A ligand is prepared.

[0165] O-(diphenylphosphino)bromobenzene (20 mmol), diphenylphosphino methylamine (20 mmol), triethylamine (50 mmol), N,N-dimethyl methanamide solvent (40 mL), and CuI catalyst (0.5 g) are added into a Schlenk bottle (100 mL) in N.sub.2 atmosphere. The mixed liquid is heated to 80 C. and kept for 12 hours at such a temperature.

[0166] After completion of the reaction, the liquid is cooled to room temperature. Insoluble substances are removed through filtration. The residual solution is separated by a chromatographic column, and is eluted by n-hexane. All solution is collected, and all solvent and volatile compositions are removed through a vacuum decompression method. Solid product obtained therein is recrystallized so as to obtain a light yellow crystalline product. A productivity of the product is 28%.

[0167] The elemental analysis results are shown as follows. Calculation values: N, 2.95; C, 78.30; H, 5.72. Measured values: N, 2.87; C, 78.41; H, 5.76.

[0168] 2. A ligand chromium compound is prepared.

[0169] The ligand (0.48 g, 1 mmol) prepared in step 1, chromium trichloride(THF).sub.3 (0.37 g, 1 mmol) and THF solvent (50 mL) are added into a Schlenk bottle (100 mL) in N.sub.2 atmosphere. The reaction liquid is stirred for 25 hours. The solvent is removed with reduced temperature. Crude product is washed by n-hexane so as to obtain a dark green solid product. A productivity of the product is 90%, and a structure thereof is shown in formula (13) as follows:

##STR00014##

[0170] The elemental analysis results are shown as follows. Calculation values: N, 2.21; C, 58.74; H, 4.29. Measured values: N, 2.15; C, 58.89; H, 4.26.

[0171] 3. A catalyst formed by the NP-ligand chromium compound as shown in formula (13) and methylaluminoxane (MAO) is used in an ethylene oligomerization reaction, and a method is described as follows.

[0172] A high pressure reactor (300 mL) is pre-treated. That is, the reactor is dried by an electric drier and is installed. The reactor is evacuated for 2 hours under a temperature being 50 C. to form a vacuum therein. A fully dried ethylene gas with a certain pressure is pumped into the reactor after N.sub.2 replacement for three times, and then a temperature of the reactor drops to room temperature.

[0173] Toluene solvent (60 mL) and methylaluminoxane (MAO) (2.5 mL) as co-catalyst are added into the reactor in an ethylene atmosphere. After stirring for 5 minutes, a toluene solution (20 mL) containing 5 mol of the NP-ligand chromium compound as shown in formula (1) is added into the reactor. A temperature of the reactor is raised to 50 C. under stirring, and reaction proceeds for 30 minutes under ethylene pressure being 4.0 MPa. The reaction goes on until a predetermined time, the stirring stops, a supply of ethylene gas stops, and the temperature of the reactor is reduced to about 5 C. A pressure of the reactor is reduced slowly, and a product after reaction is poured to an ethanol solution acidified with hydrochloric acid with a concentration being 10%. Organic products are separated by adding 100 mL of water. Liquid products are dried by anhydrous sodium sulfate, and are qualitatively and quantitatively analyzed through GC-FID methods. Solid products are collected after filtration, and are dried in vacuum at 50 C. until a weight thereof reaches a constant weight, and the mass percentage content is calculated separately.

[0174] An activity of the catalyst can be obtained through gas chromatographic analysis and calculation, and the activity of the catalyst and product compositions are shown in Table 3.

Example 34

[0175] 1. A ligand is prepared.

[0176] O-(diphenylphosphino)bromobenzene (20 mmol), diphenylphosphino ethylamine (20 mmol), triethylamine (50 mmol), N,N-dimethyl methanamide solvent (40 mL), and CuI catalyst (0.5 g) are added into a Schlenk bottle (100 mL) in N.sub.2 atmosphere. The mixed liquid is heated to 80 C. and kept for 12 hours at such a temperature.

[0177] After completion of the reaction, the liquid is cooled to room temperature. Insoluble substances are removed through filtration. The residual solution is separated by a chromatographic column, and is eluted by n-hexane. All solution is collected, and all solvent and volatile compositions are removed through a vacuum decompression method so as to obtain a white solid product. A productivity of the product is 46%.

[0178] The elemental analysis results are shown as follows. Calculation values: N, 2.86; C, 78.51; H, 5.97. Measured values: N, 2.89; C, 78.49; H, 5.96.

[0179] 2. A ligand chromium compound is prepared.

[0180] The ligand (0.49 g, 1 mmol) prepared in step 1, chromium trichloride(THF).sub.3 (0.37 g, 1 mmol) and THF solvent (50 mL) are added into a Schlenk bottle (100 mL) in N.sub.2 atmosphere. The reaction liquid is stirred for 25 hours. The solvent is removed with reduced temperature. Crude product is washed by n-hexane for several times so as to obtain a dark green solid product. A productivity of the product is 91%, and a structure thereof is shown in formula (14) as follows:

##STR00015##

[0181] The elemental analysis results are shown as follows. Calculation values: N, 2.16; C, 59.32; H, 4.51. Measured values: N, 2.13; C, 59.29; H, 4.47.

[0182] 3. A catalyst formed by the NP-ligand chromium compound as shown in formula (14) and methylaluminoxane (MAO) is used in an ethylene oligomerization reaction, and a method is described as follows.

[0183] A high pressure reactor (300 mL) is pre-treated. That is, the reactor is dried by an electric drier and is installed. The reactor is evacuated for 2 hours under a temperature being 50 C. to form a vacuum therein. A fully dried ethylene gas with a certain pressure is pumped into the reactor after N.sub.2 replacement for three times, and then a temperature of the reactor drops to room temperature.

[0184] Toluene solvent (60 mL) and methylaluminoxane (MAO) (2.5 mL) as co-catalyst are added into the reactor in an ethylene atmosphere. After stirring for 5 minutes, a toluene solution (20 mL) containing 5 mol of the NP-ligand chromium compound as shown in formula (14) is added into the reactor. A temperature of the reactor is raised to 50 C. under stirring, and reaction proceeds for 30 minutes under ethylene pressure being 4.0 MPa. The reaction goes on until a predetermined time, the stirring stops, a supply of ethylene gas stops, and the temperature of the reactor is reduced to about 5 C. A pressure of the reactor is reduced slowly, and a product after reaction is poured to an ethanol solution acidified with hydrochloric acid with a concentration being 10%. Organic products are separated by adding 100 mL of water. Liquid products are dried by anhydrous sodium sulfate, and are qualitatively and quantitatively analyzed through GC-FID methods. Solid products are collected after filtration, and are dried in vacuum at 50 C. until a weight thereof reaches a constant weight, and the mass percentage content is calculated separately.

[0185] An activity of the catalyst can be obtained through gas chromatographic analysis and calculation, and the activity of the catalyst and product compositions are shown in Table 3.

Reference Example 1

[0186] 1. A ligand is prepared.

[0187] N-2,6-diisopropyl phenyl-2-phenyl-2-chloro-imine (29.98 g, 100 mmol), o-(diphenyl phosphino) aniline (27.73 g, 100 mmol), and toluene (400 ml) are added into a Schlenk bottle (100 mL) in N.sub.2 atmosphere. The mixed liquid is heated to 120 C. and refluxed for 20 hours so as to obtain a hydrochloride of the ligand.

[0188] The hydrochloride is dissolved in ethanol (300 ml, 95%), and is dropwise added to aqueous ammonia (300 ml, 25%) for neutralization. Solid product obtained therein is collected after filtration, is dried in vacuum for 4 hours, and is recrystallized in toluene so as to obtain a white crystalline product. A productivity of the product is 85%.

[0189] The elemental analysis results are shown as follows. Calculation values: N, 5.18; C, 82.19; H, 6.71. Measured values: N, 5.06; C, 81.88; H, 6.67.

[0190] 2. A ligand chromium compound is prepared.

[0191] The ligand (0.54 g, 1 mmol) prepared in step 1, chromium trichloride(THF).sub.3 (0.37 g, 1 mmol) and THF solvent (50 mL) are added into a Schlenk bottle (100 mL) in N.sub.2 atmosphere. The reaction liquid turns to dark green. The reaction liquid is stirred for 25 hours, and then solvent is removed in vacuum. Crude product is washed by n-hexane for several times so as to obtain a dark green solid product. A productivity of the product is 92.9%, and a structure thereof is shown in formula (15) as follows:

##STR00016##

[0192] The elemental analysis results are shown as follows. Calculation values: N, 4.01; C, 63.57; H, 5.19. Measured values: N, 3.91; C, 62.79; H, 5.38.

[0193] 3. A catalyst formed by the NP-ligand chromium compound as shown in formula (15) and methylaluminoxane (MAO) is used in an ethylene oligomerization reaction, and a method is described as follows.

[0194] A high pressure reactor (300 mL) is pre-treated. That is, the reactor is dried by an electric drier and is installed. The reactor is evacuated for 2 hours under a temperature being 50 C. to form a vacuum therein. A fully dried ethylene gas with a certain pressure is pumped into the reactor after N.sub.2 replacement for three times, and then a temperature of the reactor drops to room temperature.

[0195] Toluene solvent (60 mL) and methylaluminoxane (MAO) (2.5 mL) as co-catalyst are added into the reactor in an ethylene atmosphere. After stirring for 5 minutes, a toluene solution (20 mL) containing 5 mol of the NP-ligand chromium compound as shown in formula (15) is added into the reactor. A temperature of the reactor is raised to 50 C. under stirring, and reaction proceeds for 30 minutes under ethylene pressure being 4.0 MPa. The reaction goes on until a predetermined time, the stirring stops, a supply of ethylene gas stops, and the temperature of the reactor is reduced to about 5 C. A pressure of the reactor is reduced slowly, and a product after reaction is poured to an ethanol solution acidified with hydrochloric acid with a concentration being 10%. Organic products are separated by adding 100 mL of water. Liquid products are dried by anhydrous sodium sulfate, and are qualitatively and quantitatively analyzed through GC-FID methods. Solid products are collected after filtration, and are dried in vacuum at 50 C. until a weight thereof reaches a constant weight, and the mass percentage content is calculated separately.

[0196] An activity of the catalyst can be obtained through gas chromatographic analysis and calculation, and the activity of the catalyst and product compositions are shown in Table 3.

TABLE-US-00001 TABLE 1 Activities of the catalysts and product compositions of Examples 1-8 Activity 1-C.sub.6 (10.sup.6 g/ C.sub.6.sup.# in C.sub.8.sup.# (mol (wt C.sub.6 (wt 1-C.sub.8 in C.sub.10+.sup.# PE* Examples Cr .Math. h)) %) (%) %) C.sub.8 (%) (wt %) (wt %) 1 1.32 26.0 87.0 57.5 96.4 16.5 3.4 2 7.92 38.5 85.5 51.6 96.9 9.9 1.9 3 8.42 36.2 75.4 54.2 97.3 9.6 2.5 4 7.32 37.3 92.5 57.5 97.6 7.2 2.1 5 7.48 21.5 84.7 69.0 98.3 9.5 2.5 6 8.42 24.3 95.1 68.2 98.6 7.5 3.0 7 9.52 23.2 84.5 70.1 97.3 6.7 4.1 8 6.43 20.8 73.5 68.9 98.1 10.3 2.1

[0197] According to Table 1, data in columns with sign .sup.# represent mass percentage content of each composition in the oligomerization products, and *PE represents mass percentage content thereof in total mass.

TABLE-US-00002 TABLE 2 Activities of the catalysts and product compositions of Examples 9-21 Activity 1-C.sub.6 (10.sup.6 g/ C.sub.6.sup.# in (mol (wt C.sub.6 C.sub.8.sup.# 1-C.sub.8 in C.sub.10+.sup.# PE* Examples Cr .Math. h)) %) (%) (wt %) C.sub.8 (%) (wt %) (wt %) 9 6.24 25.1 75.9 71.1 98.5 3.8 1.4 10 0.42 27.1 64.2 57.6 97.1 15.3 1.0 11 1.32 24.7 69.5 61.5 97.9 13.8 2.6 12 3.03 34.3 82.5 58.5 98.1 7.2 1.8 13 0.52 20.6 74.5 67.6 99.2 11.8 1.0 14 0.06 23.8 75.2 68.5 98.4 7.7 1.3 15 4.61 29.2 94.6 63.3 98.6 7.5 2.6 16 5.31 27.3 86.2 67.4 97.3 5.3 1.0 17 4.67 32.1 87.4 65.5 97.8 2.4 1.1 18 0.87 26.0 77.1 55.2 98.5 18.8 1.0 19 3.21 23.8 92.3 69.3 97.1 6.9 2.1 20 1.17 24.3 82.2 66.9 96.5 8.8 1.2 21 1.78 21.4 73.9 68.6 97.9 10.0 3.2

TABLE-US-00003 TABLE 3 Activities of the catalysts and product compositions of Examples 22-34 and Reference Example 1 Activity 1-C.sub.6 (10.sup.6 g/ C.sub.6 in (mol (wt C.sub.6 C.sub.8 1-C.sub.8 in C.sub.10+ PE Examples Cr .Math. h)) %) (%) (wt %) C.sub.8 (%) (wt %) (wt %) 22 5.75 29.7 67.3 62.3 99.2 8.0 3.2 23 6.25 26.5 96.3 69.2 97.2 4.3 2.5 24 3.46 29.2 62.7 55.5 98.3 15.3 3.8 25 2.43 31.6 79.5 57.3 98.2 11.1 2.4 26 2.67 30.5 94.6 60.3 97.7 9.2 1.6 27 2.53 21.8 93.2 67.5 98.2 10.7 2.0 28 3.92 22.5 91.5 67.6 97.6 9.9 2.4 29 3.18 22.3 96.8 65.4 98.3 12.3 2.4 30 2.71 24.8 75.6 59.7 98.2 15.5 3.0 31 3.12 86.2 76.3 3.4 98.4 10.4 2.2 32 2.18 90.2 90.6 3.1 99.0 6.7 1.0 33 1.43 92.1 96.5 3.4 99.0 4.5 1.0 34 1.32 89.3 92.5 4.6 99.0 6.1 1.2 Reference 0.38 59.8 68.0 30.2 100.0 10.5 50.9 Example 1