Pyrrole bridged ethylene oligomerization catalyst composition and applicationTechnical Field
The invention relates to the field of ethylene oligomerization, in particular to the field of ethylene trimerization or ethylene tetramerization, and more particularly relates to a pyrrole bridged ethylene oligomerization catalyst composition and application of the composition in ethylene oligomerization or ethylene trimerization or ethylene tetramerization.
Background
Alpha-olefins are important organic raw materials and chemical intermediates, and are mainly applied to the fields of producing high-quality Polyethylene (PE), lubricating oil base oil, plasticizer, detergent and the like. The linear low-density polyethylene (LLDPE) produced by copolymerizing 1-hexene or 1-octene and ethylene can obviously improve various properties of PE, in particular can obviously improve mechanical properties, optical properties, tear strength and impact strength of the PE, and the product is very suitable for the fields of packaging films, agricultural covering films such as greenhouse, greenhouse and the like. Polyolefin plastomers and polyolefin elastomers produced by copolymerizing 1-octene with ethylene are currently in great commercial consumption and demand. With the continued development of the polyolefin industry, the worldwide demand for alpha-olefins has grown rapidly.
Ethylene oligomerization is one of the most important reactions in the olefin polymerization industry, by which inexpensive small molecule ethylene can be converted into products with high added value, i.e., different long chain alpha-olefins. Since the 70 s of the last century, research on the polymerization and oligomerization of olefins catalyzed by transition metal complexes has been increasingly receiving attention from scientists, and efforts have been made to develop new catalysts and to improve existing catalysts, to increase the activity of the catalysts and the selectivity of the catalytic products. Among the many studies that have been carried out the earliest and most rapidly, the more concentrated are nickel-based cationic catalytic systems, as reported earlier in U.S. Pat. nos. 3686351a and 3676523a, and the shell corporation SHOP process based on this patent technology. O-P bridged ligand is involved in shell company SHOP process, but the catalyst contains toxic organic phosphorus group, and has complex synthesis steps and poor stability. A number of patents such as the O-O, P-N, P-P and N-N type complex nickel catalysts have been developed later, for example, JP11060627, WO9923096A1, CN1401666A, CN1769270A and the like. However, the catalysts obtained from the above patents have the disadvantage of being relatively complex in terms of the preparation process.
Patent WO2004056478A1 by Sasol discloses PNP framework catalysts having a C8 component selectivity of about 66wt% and a C6 component selectivity of about 21wt% in ethylene tetramerization, wherein the content of 1-hexene in the C6 component is only 82%, and the total selectivity of 1-hexene and 1-octene is about 84%. In U.S. Pat. No. 3, 20100137669A1, a symmetrical framework-type PCCP catalyst is disclosed which is more stable than PNP systems in ethylene tetramerization, the total selectivity of 1-hexene and 1-octene not exceeding 85%
In these reaction systems, the byproducts such as cycloolefin and cyclized product present in the C6 product can be removed by separation and purification, but the economy of the whole process is disadvantageous.
Disclosure of Invention
Aiming at the problems existing in the prior art, the invention provides a novel pyrrole bridged ethylene oligomerization catalyst composition, which has the characteristics of high catalytic activity, high selectivity and the like, and has better industrial application prospect and economic value.
In view of the above-mentioned shortcomings of the prior art, the present inventors have conducted intensive studies on this type of phosphorus-containing catalyst, and have found a pyrrole bridged ethylene oligomerization catalyst composition comprising a catalyst ligand represented by formula (I), a transition metal compound and an aluminum-containing cocatalyst, or a catalyst complex represented by formula (II) and an aluminum-containing cocatalyst. The catalyst ligand or the complex is of a pyrrole bridged biphosphine structure, and the aromatic ring contains an ortho halogen substituent, so that the catalyst ligand or the complex is novel in structure, simple to prepare and low in cost. The catalyst composition can effectively catalyze ethylene oligomerization, especially ethylene trimerization and tetramerization, the catalytic activity is more than 0.8X108g·mol(Cr)-1·h-1 and can reach 3.0X108g·mol(Cr)-1·h-1, and the total selectivity of 1-hexene and 1-octene is more than 93wt% and can reach 97wt% under different conditions. Compared with the catalyst of the comparative example, the catalyst composition provided by the invention has obviously improved catalyst activity, especially greatly improved content of 1-hexene in C6, and obviously reduced byproducts such as cycloolefin, cyclized product and the like. Therefore, the catalyst composition provided by the invention has the characteristics of high catalytic activity, high selectivity and the like, and has good industrial application prospect and economic value.
The first aspect of the invention provides a pyrrole bridged ethylene oligomerization catalyst composition, which comprises a catalyst ligand shown in a formula (I), a transition metal compound and an aluminum-containing cocatalyst, or comprises a catalyst complex shown in a formula (II) and an aluminum-containing cocatalyst,
In the formula (I), R1、R2、R3、R4 are the same or different and are each independently selected from hydrogen or fluorine atoms;
In the formula (II), R1'、R2'、R3'、R4' are the same or different and are each independently selected from hydrogen or fluorine atoms, M is a transition metal, X is selected from halogen, and n is an integer of 1-3.
According to some embodiments of the invention, M in formula (II) is selected from at least one of chromium, molybdenum, iron, titanium, zirconium and nickel.
According to some embodiments of the invention, the aluminum-containing cocatalyst is an organoaluminum compound, preferably at least one from the group consisting of an alkylaluminum compound, an alkylaluminum compound and an alkylaluminum chloride compound, more preferably at least one from the group consisting of methylaluminoxane, trimethylaluminum, triethylaluminum, triisobutylaluminum, tri-n-hexylaluminum, tri-n-octylaluminum, diethylaluminum monochloride, ethylaluminum dichloride, ethylaluminoxane and modified methylaluminoxane, more preferably at least one from the group consisting of modified methylaluminoxane, methylaluminoxane and triethylaluminum. In the present invention, the modified methylaluminoxane may be an alkyl modified methylaluminoxane, such as alkyl modified methylaluminoxane MMAO which is conventional in the art.
According to some embodiments of the invention, the transition metal compound is selected from at least one of chromium, molybdenum, iron, titanium, zirconium and nickel compounds, preferably at least one of chromium acetylacetonate, chromium isooctanoate, chromium tris (tetrahydrofuran) trichloride, and chromium bis (tetrahydrofuran) dichloride.
According to some embodiments of the present invention, the molar ratio of the transition metal compound, the catalyst ligand of formula (I) and the aluminum-containing cocatalyst, calculated as metal elements, is 1:0.1-10:1-1000, preferably 1:0.25-2:10-700, more preferably 1:0.5-2:100-500.
According to some embodiments of the present invention, the molar ratio of the catalyst complex of formula (II) to the aluminum-containing cocatalyst is from 1:1 to 1000, preferably from 1:10 to 700, more preferably from 1:100 to 500.
According to some embodiments of the invention, the organic solvent may be an organic solvent commonly used for polymerization, preferably at least one selected from methylcyclohexane, heptane, cyclohexane, toluene and xylene.
According to one embodiment of the present invention, a pyrrole bridged ethylene oligomerization catalyst composition comprises a catalyst ligand of formula (I), a transition metal compound, and an aluminum-containing cocatalyst;
In formula (I), R1、R2、R3、R4, which are the same or different, are each independently selected from hydrogen or fluorine atoms.
According to another embodiment of the present invention, a pyrrole bridged ethylene oligomerization catalyst composition comprises a catalyst complex of formula (II) and an aluminum-containing cocatalyst,
In the formula (II), R1'、R2'、R3'、R4' are the same or different and are each independently selected from hydrogen or fluorine atoms, M is a transition metal, X is selected from halogen, n is an integer of 1-3, preferably M is selected from at least one of chromium, molybdenum, iron, titanium, zirconium and nickel.
In a second aspect the present invention provides a process for the oligomerization of ethylene comprising carrying out the oligomerization of ethylene in an organic solvent in the presence of a catalyst composition according to the above.
According to some embodiments of the invention, the concentration of the catalyst composition is 0.1 to 10. Mu. Mol/L on a metal basis, calculated on the volume of the organic solvent. For example, when the transition metal is Cr, the catalyst composition has a concentration of 0.1 to 10. Mu. Mol/L in terms of Cr.
According to some embodiments of the invention, the reaction conditions may be those commonly used in the art. Preferably, the reaction temperature of the ethylene oligomerization is from 0 to 200 ℃, preferably from 0 to 100 ℃, more preferably from 30 to 100 ℃.
According to some embodiments of the invention, the reaction conditions may be those commonly used in the art. Preferably, the ethylene oligomerization reaction has an ethylene pressure of 0.1 to 20.0MPa, preferably 0.5 to 5.0MPa, more preferably 2.0 to 5.0MPa.
According to some embodiments of the present invention, in the ethylene oligomerization process, any two of the catalyst ligand, the transition metal compound and the aluminum-containing cocatalyst in the catalyst composition may be premixed and then added to the reaction system together with the other catalyst ligand, the transition metal compound and the aluminum-containing cocatalyst, or the three components may be directly added to the reaction system for in-situ synthesis, or the catalyst ligand, the transition metal compound and the aluminum-containing cocatalyst may be premixed and then directly added to the reaction system in the form of a mixture.
According to some embodiments of the present invention, in the above-mentioned ethylene oligomerization process, the catalyst complex and the aluminum-containing cocatalyst in the catalyst composition may be pre-mixed and then added together to the reaction system, or both components of the catalyst complex and the aluminum-containing cocatalyst may be directly added to the reaction system.
In a third aspect the present invention provides a process for the trimerisation or tetramerisation of ethylene comprising carrying out the trimerisation or tetramerisation reaction of ethylene in an organic solvent in the presence of a catalyst composition according to the above.
According to some embodiments of the invention, the concentration of the catalyst composition is 0.1 to 10. Mu. Mol/L on a metal basis, calculated on the volume of the organic solvent. For example, when the transition metal is Cr, the catalyst composition has a concentration of 0.1 to 10. Mu. Mol/L in terms of Cr.
According to some embodiments of the invention, the reaction conditions may be those commonly used in the art. Preferably, the reaction temperature of the ethylene oligomerization is from 0 to 200 ℃, preferably from 0 to 100 ℃, more preferably from 30 to 100 ℃.
According to some embodiments of the invention, the reaction conditions may be those commonly used in the art. Preferably, the ethylene oligomerization reaction has an ethylene pressure of 0.1 to 20.0MPa, preferably 0.5 to 5.0MPa, more preferably 2.0 to 5.0MPa.
According to some embodiments of the present invention, in the ethylene oligomerization process, any two of the catalyst ligand, the transition metal compound and the aluminum-containing cocatalyst in the catalyst composition may be premixed and then added to the reaction system together with the other catalyst ligand, the transition metal compound and the aluminum-containing cocatalyst, or the three components may be directly added to the reaction system for in-situ synthesis, or the catalyst ligand, the transition metal compound and the aluminum-containing cocatalyst may be premixed and then directly added to the reaction system in the form of a mixture.
According to some embodiments of the present invention, in the above-mentioned ethylene oligomerization process, the catalyst complex and the aluminum-containing cocatalyst in the catalyst composition may be pre-mixed and then added together to the reaction system, or both components of the catalyst complex and the aluminum-containing cocatalyst may be directly added to the reaction system.
The invention has the beneficial effects that:
(1) The catalyst ligand or the complex in the pyrrole bridged ethylene oligomerization catalyst composition is of a pyrrole bridged biphosphine structure, and the preparation is simple and the cost is low.
(2) The pyrrole bridged ethylene oligomerization catalyst composition can effectively catalyze ethylene oligomerization reactions, especially ethylene trimerization and tetramerization reactions, has high catalyst activity and good product selectivity, and obviously reduces byproducts such as cycloolefin, cyclized products and the like in a C6 product.
(3) The catalyst composition provided by the invention has the characteristics of high catalytic activity, high selectivity and the like, and has good industrial application prospect and economic value.
Detailed Description
In order that the invention may be more readily understood, the invention will be described in detail below with reference to the following examples, which are given by way of illustration only and are not limiting of the scope of application of the invention.
The test method and the equipment used in the test are as follows:
(1) In the embodiment of the invention, nuclear magnetic resonance is detected by using a Bruker AV400 type nuclear magnetic resonance apparatus, wherein the nuclear magnetic resonance is detected under the condition that deuterated chloroform is used as a solvent.
(2) The room temperature test gas chromatograph adopts Agilent 7890 chromatograph to detect, wherein the detection conditions of the gas chromatograph are chromatographic column SE-54, high-purity nitrogen carrier gas and FID detector, and the column temperature adopts two-stage temperature programming.
[ PREPARATION EXAMPLE 1]
Preparation of catalyst ligand I1(R1＝R2＝R3＝R4 =f
N-Boc-2, 5-dibromopyrrole (15 mmol) and tetrahydrofuran (200 mL) were added to a three-necked flask under the protection of nitrogen, cooled to-78 ℃, N-butyllithium (30 mmol) was added dropwise, stirred for 1 hour, bis- (2-fluorophenyl) phosphorus chloride (30 mmol) was added dropwise, the reaction was allowed to proceed to room temperature for 18 hours after the addition was completed, and the solvent was removed under reduced pressure. The residue was dissolved in toluene (50 mL) under nitrogen protection, heated to 155 ℃ for 18 hours, and after the reaction was completed, the solvent was removed in vacuo to give a yellow solid, which was recrystallized from toluene to give a white solid product, namely catalyst ligand I1.
1H-NMR(δ,ppm,CDCl3,TMS):6.9~7.2(m,16H,Ar-H),5.9(s,2H,CH),4.9(s,1H,NH)。
[ PREPARATION EXAMPLE 2]
Preparation of catalyst ligand I2(R1＝R2＝H,R3＝R4 =f
N-Boc-2, 5-dibromopyrrole (15 mmol) and tetrahydrofuran (200 mL) are added into a three-necked flask under the protection of nitrogen, the mixture is cooled to-78 ℃, N-butyllithium (30 mmol) is added dropwise, the mixture is stirred for 1 hour, bis- (2-fluorophenyl) phosphorus chloride (15 mmol) is added first for half an hour, diphenyl phosphorus chloride (15 mmol) is added again, the mixture is transferred to room temperature for reaction for 18 hours after the addition, and the solvent is removed under reduced pressure after the reaction is completed. The residue was separated by column chromatography, dissolved in toluene (50 mL) under nitrogen protection, heated to 155 ℃ for 18 hours, the solvent was removed in vacuo after completion of the reaction, and the residue was recrystallized using toluene to give the product as a white solid, i.e., catalyst ligand I2.
1H-NMR(δ,ppm,CDCl3,TMS):7.0~7.3(m,18H,Ar-H),6.0(s,2H,CH),5.1(s,1H,NH)。
[ PREPARATION EXAMPLE 3]
Preparation of the catalyst complex II1(R1＝R2＝H,R3＝R4 =f, M is Cr, X is Cl, n is 2
5Mmol of catalyst ligand I2 and 5mmol of CrCl3(THF)3 were transferred to a Schlenk tube under nitrogen, 50mL of toluene solution was added, and then stirred for 8 hours at 80 ℃. And cooling the reaction liquid to room temperature, carrying out suction filtration, washing the obtained solid with toluene and normal hexane respectively, and carrying out vacuum drying to obtain the corresponding biphosphine chromium complex, namely the catalyst complex II1.
1H-NMR(δ,ppm,CDCl3 TMS) 7.0-7.3 (m, 18H, ar-H), 6.0 (s, 2H, CH), 5.1 (s, 1H, NH). Elemental analysis testing C28H21Cl2CrF2NP2(calcd)：C,56.50(56.59);H,3.88(3.56);N,2.29(2.36).
[ Example 1]
A300 mL stainless steel polymerizer was used. The autoclave was heated to 80 ℃, evacuated, replaced several times with nitrogen, then replaced by ethylene and cooled to the set temperature. Then methylcyclohexane was added at 40℃and 0.5. Mu. Mol of chromium acetylacetonate, catalyst ligand I1 (obtained in preparation example 1) and cocatalyst-Modified Methylaluminoxane (MMAO) were simultaneously added, the total volume of the mixture was 100mL, wherein the molar ratio of chromium acetylacetonate (calculated as chromium), ligand and cocatalyst was 1:2:500, i.e., the addition of ligand I1 was 1.0. Mu. Mol/L, MMAO calculated as Cr and 250. Mu. Mol, the reaction pressure was controlled at 3MPa, the temperature was 40℃and ethylene was introduced to carry out oligomerization of ethylene.
After half an hour, the reaction was completed, the system was cooled to room temperature, the gas phase product was collected in a gas metering tank, the liquid phase product was collected in a conical flask, and 1mL of ethanol was added as a terminator to terminate the reaction. The gas-liquid phase product was measured and analyzed by gas chromatography (chromatograph is Hewlett-packard 5890). The data results are shown in Table 1.
[ Example 2]
The same as in example 1, except that catalyst ligand I1 was replaced with catalyst ligand I2. The data results are shown in Table 1.
[ Example 3]
A300 mL stainless steel polymerizer was used. The autoclave was heated to 80 ℃, evacuated, replaced several times with nitrogen, then replaced by ethylene and cooled to the set temperature. Then methylcyclohexane was added at 40 ℃, then 0.5. Mu. Mol of catalyst complex II1(R1＝R2＝H,R3＝R4＝F,M＝Cr,Xn＝Cl2 was added, and finally cocatalyst Modified Methylaluminoxane (MMAO) was added 100. Mu. Mol, the total volume of the mixture was 100mL, wherein the molar ratio of catalyst complex to cocatalyst was 1:500. Controlling the reaction pressure to 3MPa and the temperature to 40 ℃, introducing ethylene, and carrying out ethylene oligomerization.
After half an hour, the reaction was completed, the system was cooled to room temperature, the gas phase product was collected in a gas metering tank, the liquid phase product was collected in a conical flask, and 1mL of ethanol was added as a terminator to terminate the reaction. The gas-liquid phase product was measured and analyzed by gas chromatography (chromatograph is Hewlett-packard 5890). The data results are shown in Table 1.
[ Example 4]
The procedure is as in example 1, except that the modified methylaluminoxane is replaced by triethylaluminum. The data results are shown in Table 1.
[ Example 5]
The same as in example 1, except that the reaction temperature was changed from 40℃to 30 ℃. The data results are shown in Table 1.
[ Example 6]
The same as in example 1, except that the reaction temperature was changed from 40℃to 60 ℃. The data results are shown in Table 1.
[ Example 7]
The same as in example 1, except that the reaction temperature was changed from 40℃to 100 ℃. The data results are shown in Table 1.
[ Example 8]
The same as in example 3 was found to be different in that the reaction pressure was replaced with 5MPa from 3 MPa. The data results are shown in Table 1.
[ Example 9]
The procedure is as in example 1, except that the molar ratio of chromium acetylacetonate (calculated as chromium), ligand and cocatalyst is replaced by 1:0.5:100 with a 1:2:500 molar ratio. The data results are shown in Table 1.
[ Example 10]
The procedure is as in example 1, except that the molar ratio of chromium acetylacetonate (calculated as chromium), ligand and cocatalyst is replaced by 1:2:700 with a 1:2:500 ratio. The data results are shown in Table 1.
[ Example 11 ]
The procedure is as in example 1, except that the molar ratio of chromium acetylacetonate (calculated as chromium), ligand and cocatalyst is replaced by 1:10:1000 with a 1:2:500 molar ratio. The data results are shown in Table 1.
[ Example 12 ]
The difference from example 3 is that the molar ratio of catalyst complex to cocatalyst is 1:500 instead of 1:100. The data results are shown in Table 1.
[ Example 13 ]
The difference from example 3 is that the molar ratio of catalyst complex to cocatalyst is 1:500 instead of 1:700. The data results are shown in Table 1.
[ Example 14 ]
The difference from example 3 is that the molar ratio of catalyst complex to cocatalyst is 1:500 instead of 1:1000. The data results are shown in Table 1.
Comparative example 1
Ethylene oligomerization was carried out using the compound bis [ (S, S) - (phenyl)2 PCH (Me) CH (Me) P (phenyl)2 dichloro (μ -chloro) chromium ].
The procedure was as described in comparative example 2 in CN104169003 a. The data results are shown in Table 1.
Comparative example 2
Ethylene oligomerization was carried out using the compound bis [ (S, S) - (o-fluoro-phenyl)2 PCH (Me) CH (Me) P (o-fluoro-phenyl)2 dichloro (μ -chloro) chromium ].
The procedure was as described in example 4 of CN104169003 a. The data results are shown in Table 1.
TABLE 1
As can be seen from the data in Table 1, the catalytic activity of the pyrrole bridged biphosphine catalyst provided by the invention exceeds 0.8X108g·mol(Cr)-1·h-1, the highest activity is 3.0X108g·mol(Cr)-1·h-1, and under different conditions, the total selectivity of 1-hexene and 1-octene is more than 93wt% and the highest activity is more than 97wt%. Compared with the catalyst of comparative example 1, the catalyst composition provided by the invention has obviously improved catalyst activity, especially greatly improved content of 1-hexene in C6, obviously reduced byproducts such as cycloolefin and cyclized product, and obviously improved catalyst activity, which indicates that the catalyst disclosed by the invention has better performance. The change of the structure of the catalyst ligand or the complex influences the coordination capacity and the electronic effect of the ligand or the complex, so that the effect on the catalytic performance is obvious.
The catalyst composition can effectively catalyze ethylene trimerization and tetramerization reactions, and has the advantages of rapid initiation, stable operation, good repeatability, strong practicability and wide industrialization prospect.
What has been described above is merely a preferred example of the present invention. It should be noted that other equivalent modifications and improvements will occur to those skilled in the art, and are intended to be within the scope of the present invention, as a matter of common general knowledge in the art, in light of the technical teaching provided by the present invention.