RU2248374C1 - Method for scouring of blast furnace, two-component immobilized catalyst for ethylene polymerization, method for production the same (variants), and method for production of polyethylene using this catalyst - Google Patents

Abstract

FIELD: chemical industry, in particular two-component heterogeneous immobilized catalyst for ethylene polymerization.

SUBSTANCE: claimed catalyst includes alumina, mixture of transition metal complexes with nitrogen skeleton ligands (e.g., iron chloride bis-(imino)pyridil complex and nickel bromide bis-(imino)acetonaphthyl complex). According the first embodiment catalyst is prepared by application of homogeneous mixture of transition metal complexes onto substrate. iron chloride bis-(imino)pyridil complex and nickel bromide bis-(imino)acetonaphthyl complex (or vise versa) are alternately applied onto substrate. According the third embodiment catalyst is obtained by mixing of complexes individually applied onto substrate. Method for polyethylene producing by using catalyst of present invention also is disclosed.

EFFECT: catalyst for producing polyethylene with various molecular weights, including short chain branches, from single ethylene as starting material.

7 cl, 5 tbl, 27 ex

Description

The invention relates to the field of chemical industry, in particular to the creation of more economical new two-component (binary) heterogeneous supported ethylene polymerization catalysts.

It is known that modern highly active catalytic systems based on metallocene catalysts lead to the production of polymers, in particular polyethylene with a narrow molecular weight distribution (MMP), which creates significant problems in their processing.

In order to improve the processability of polyolefins, they resort to the method of expanding MMP by mixing polymer melts with different molecular weights (MM), which leads to significant energy costs.

A more convenient method is the so-called “reactor mixing” method, which allows one-center catalyst mixtures or a combination of one-center and conventional Ziegler-Natta catalysts [Cho H.S., Choi Y.H., Lee W.Y. to obtain polymers with good rheological properties Characteristics of ethylene polymerization over Ziegler-Natta / metallocene catalysts comparison between hybrid and mixed catalysts. Catal. Today 2000, v. 63, p. 523-530; Margues M.F.W., Pombo C.C., Silva R.A., Conte A. Binary metallocene supported catalyst propylene polymerization. Eur. Polymer J., 2003, v. 39, p. 561-567; Application WO 03/029303, C 08 F 4/64, 04/10/2003].

Known catalysts for the polymerization of ethylene and its copolymerization with α-olefins, consisting of supported on a carrier, for example SiO ₂ , Ziegler-Natta catalyst ("early" metal), and then added to it a complex based on methylaluminoxane (MAO) and the tridental compound FeCl ₂ (“Late” metal). As a result of mixing under certain conditions, the obtained powdered supported catalyst is used for polymerization and copolymerization. The resulting polymer has an MMP (M _w / M _n ) = 28.5 [Application WO 99/12981, C 08 F 4/70, C 07 D 213/53, C 07 F 15/02, 03/18/1999].

Also known is a catalyst consisting of a mixture supported on SiO ₂ , or Al ₂ O ₃ , or MgCl ₂ , or another carrier of a tridentant nitrogen-containing bis (imino) pyridinium Fe or Co complex and a Ziegler-Natta or metallocene catalyst, or supported Cr oxide catalysts for the polymerization and copolymerization of α-olefins. [Application WO 00/69869, C 07 F 15/00, 15/02, 15/06; C 08 F 10/00, 4/64, 4/68, 04/12/2000].

The closest in technical essence is a catalytic system consisting of a compound of the “early” metal (Ti, Zr, Hf) with the corresponding ligand and a compound of the “late” metal (Ni, Fe, Pd) with the corresponding ligand with a nitrogen skeleton, which are deposited on a preliminary an optimally prepared carrier, for example SiO ₂ , followed by the addition of an activator, preferably in the presence of a monomer [Application WO 98/38228, C 08 F 4/44, 07/17/2001].

An advantage of this invention is the requirement that both components (“early” and “late” transition metals) having different catalytic centers, are relatively close in nature and therefore could provide the synthesis of such polymers that would mix well. The invention also stipulates that during polymerization it is better not to use comonomers, but to obtain polyethylene with varying degrees of branching due to the composition of the catalysts. Unfortunately, the patent contains only two examples that describe the polymerization of ethylene in mixtures of only homogeneous catalysts, i.e. not applied. Example 1 shows the polymerization of ethylene at 50 ° C on the 1,2-bis (2,6-isopropylphenylimino) -acenaphthyl NiBr ₂ complex (3.2 · 10 ^-6 mol) and dicyclopentadienyl zirconium chloride (0.17 · 10 ^-6 mol), t .e. the specific fraction of Ni (χ _Ni ) in the mixture with Zr is 0.95; methylaluminoxane (MAO) / Σ _cat = 4450: 1, mol / mol; activity = 39640 kg / mol _cat · MPa · hour; the amount of CH ₃ / 1000C = 21. In example No. 2: T _n = 40 ° C; MAO / Σ _cat = 3220: 1; χ _Ni = 0.87; activity - 5000 kg / mol _cat · MPa · hour; CH ₃ / 1000C = 12.

The main disadvantages of the prototype are the absence of the examples claimed in the claims on the polymerization of ethylene on catalyst compositions supported on a carrier, which would make it possible to evaluate the economic value of the patent (polymerization at elevated temperatures> 50 ° C; there is no data on the molar ratio of MAO to the catalyst mixture at application, since in the above examples on homogeneous mixtures it is too high and equal to ~ 4000: 1), and also confirm the purpose of the invention: obtaining branched polymers in the absence of comonomer in real industrial conditions.

In the published literature, we were unable to identify articles and patents describing supported catalytic systems based on a binary mixture of complexes of “late” metals with ligands with a nitrogen skeleton.

The invention solves the problem of synthesizing supported on a silicon dioxide catalysts based on a binary mixture of complexes of “late” metals with ligands with a nitrogen skeleton, which in real conditions using only ethylene to obtain a wide range of polyethylene (PE) with various MM and MMR, including short chain branches.

The problem is solved in that the bis (imino) pyridyl complex of iron (I) chloride and the bis (imino) acenaphthyl complex of nickel (II) bromide of the following structures are used as complexes of “late” metals:

where (I) - R ₁ = cyclohexyl, R ₂ = R ₃ = CH ₃ ; (II) - R ₁ = cyclopentyl, R ₂ = R ₃ = CH ₃ and methylaluminoxane.

As the substrate (carrier) using silicon dioxide SiO ₂ brand "Davison 952W".

The ratio of molar fractions of iron to molar fractions of nickel is 1: 1-1: 9.

If the iron content in the mixture of complexes is greater than the nickel content, then the activity of the catalyst increases, but the short chain branching of the obtained polyethylene decreases. With a ratio higher than 1: 9, the short chain branching of the obtained polyethylene increases, but the activity of the catalyst decreases.

The catalyst according to the invention is prepared in three variants of the method.

According to the first option, it is prepared by applying to the substrate a homogeneous mixture of complexes of “late” transition metals, such as the bis (imino) pyridyl complex of iron chloride and the bis (imino) acenaphthyl complex of nickel bromide.

In the second embodiment, the bis (imino) pyridyl complex of iron chloride is alternately applied to the substrate, and then the bis (imino) acenaphthyl complex of nickel bromide or vice versa.

In the third embodiment, it is prepared by displacing complexes individually deposited on a substrate.

Toluene and n-hexane are used as solvents in the deposition of the catalyst.

As a cocatalyst, MAO is used during application.

Suspension polymerization of ethylene is carried out at a pressure of 0.3-1.0 MPa and a temperature of 50-80 ° C.

As solvents for polymerization, n-hexane, n-heptane, gasoline, etc. are used.

The polymerization of ethylene, depending on the variant of the method of preparing the binary supported catalyst, is carried out in the presence of cocatalyst aluminum triisobutyl (Al [i-C ₄ H ₉ ] ₃ ) or without it.

The following are examples illustrating the invention.

Example 1

Preparation of the substrate - silicon dioxide.

Preparation of SiO ₂ for deposition is carried out according to the conventional method: SiO _{2 is} calcined at 650 ° C for 4 hours in an atmosphere of inert argon gas. The carrier substrate thus prepared is stored in a sealed ampoule in a desiccator.

Example 2

Preparation of a mixture of silicon dioxide with methylaluminoxane.

Immediately prior to application, SiO _{2 is} degassed from residual air (oxygen) for 1 h at room temperature (t _room ) by evacuation. For all methods of catalyst deposition, SiO _{2 is used} with MAO previously deposited on its surface at the rate of 10-18 wt.% Al. For example, in the case of applying MAO (10 wt.% Al) to 1.0 g of SiO ₂ add 0.27 g of a 10% solution of MAO in toluene (F. Witco), which corresponds to 3.1 ml or 4.65 100 ^-3 mol, then add 7 ml of toluene solution; when applied to 1.0 g of SiO ₂ 15-18 wt.% Al add 0.47 g of a 10% solution of MAO in toluene (5.4 ml or 8.1 · 10 ^-3 mol) and 5 ml of toluene solution.

The calculated amount of MAO is applied in an inert atmosphere at t _room in a glass two-necked flask with a magnetic stirrer for 3 hours. Then, the SiO ₂ + MAO mixture (SMAO) is evacuated from the toluene at t _room and washed twice with excess of (non-applied) MAO twice with toluene. The amount of MAO in the toluene wash solution is determined by Fourier transform spectroscopy using a characteristic absorption band of ~ 1200 cm ^-1 . After the first washing, a small amount of MAO is washed out of the carrier. After the second wash, the amount of MAO applied is retained. Next, the final drying of SMAO is carried out by evacuation with stirring. SMAO preparation is carried out before each synthesis of the supported catalyst.

Example 3

Synthesis of supported catalyst In based on 2,6-bis- [1- (2,4-dimethyl-6-cyclohexylphenylimino) ethyl] pyridine iron (I) chloride.

3.2 mg of I and 5 ml of toluene are added to a two-necked flask containing 0.57 g of SMAO in an inert atmosphere at t _room . Application I is carried out for 1 h with constant stirring (t _room ). The molar ratio of MAO: I is 640: 1. Drying is carried out by evacuation (t _room ) to constant weight. Obtain 0.573 g of dry supported catalyst In containing 4.9 · 10 ^-6 mol of catalyst I.

Example 4. (control).

Polymerization of ethylene on a supported catalyst In.

Ethylene polymerization is carried out in a steel autoclave equipped with a 150 ml stirrer, in which 44 ml of n-hexane, 0.73 ml (1.1 · 10 ^-4 mol) of a solution of [Al (i-C ₄ H ₉ ) ₃ ] are loaded and 0.1328 g of In with 5 ml of n-hexane. Al (i-C ₄ H ₉ ) ₃ / Fe (In) = 100: 1, mol / mol.

The polymerization is carried out at 70 ° C with an ethylene pressure of 0.3 MPa. The process is interrupted by adding ethyl alcohol to the reaction mixture. The resulting polymer suspension is filtered and dried in vacuo at 60 ° C. Polyethylene (PE) yield 18.1 g; activity 54850 kg PE / mol _cat · MPa · h; [η] = 3.98 dl / g; M _v = 419 · 10 ³ ; ρ = 966.5 kg / m ³ ; _Mp = 139.5 ° C; Δ N _pl = 186.69 J / g; CH ₃ / 1000C = 0.3.

Example 5

Synthesis of supported catalyst IIn based on [1,2-bis- (2-cyclopentyl-4,6-dimethylphenylimino) acenaphthene] nickel bromide II.

In a two-necked flask containing 0.8 g of SMAO in an inert atmosphere, add 7 ml of toluene at 0 ° C and 5.3 mg of II. Application II is carried out with constant stirring for 1 h at 0 ° C. Then, toluene (t _room ) is removed by vacuum, the residue is again cooled to 0 ° C, 5 ml of n-hexane and 0.3 ml (0.0263 g) are added 10 % MAO solution in toluene and at 0 ° C with constant stirring, apply MAO for 1 h. Σ MAO / II = 620: 1. Drying IIn is carried out to constant weight by evacuation from the solvent. 1 g of supported catalyst IIn contains 8.5 · 10 ^-6 moles of catalyst II.

Example 6. (control).

Polymerization of ethylene on IIn.

The polymerization is carried out according to example 4, but at 50 ° C; the weight of IIn is 0.1357 g; cocatalyst (Al (i-C ₄ H ₉ ) ₃ ) is absent. The yield of PE is 9.08 g, the activity is 25500 kg PE / mol _cat · MPa · h; [η] = 4.0 dl / g; M _v = 280 · 10 ^-3 ; ρ = 933 kg / m ³ ; _Mp = 123.6 ° C; Δ N _pl = 118.4 J / g; CH ₃ / 1000C = 16.9.

Example 7

Synthesis of supported catalyst IIIn on a binary mixture of I and II (first method).

6.3 mg (9.56 · 10 ^-6 mol) I and 7.4 mg (9.97 · 10 ^-6 mol) II of catalysts and 10 ml of toluene are added to 1.8 g of SMAO in an inert atmosphere at 0 ° С , with stirring and for 1 h at 0 ° C, the binary mixture of I and II is applied. Then the resulting mixture was freed from toluene by vacuum at t _room , cooled again to 0 ° C. Σ MAO / Σ cat = 525: 1, mol / mol. The final drying of the obtained catalyst IIIn is carried out by evacuation of n-hexane with stirring at t _room 1 g of the supported catalyst IIIn contains 7.5 mg of a mixture of I and II or 3.4 mg (5.19 · 10 ^-6 mol) I and 4.1 mg (5.42 · 10 ^-6 mol) II.

The proportion of iron χ _Fe = [Fe] / ([Fe] + [Ni]) = 0.49; (χ _Ni = 0.51).

Example 8-11

Polymerization of ethylene on IIIn.

The polymerization on the catalyst IIIn is carried out according to example 6, but under the conditions shown in table 1. The table also shows the results.

Table 1. No. pr. Solvent The amount of IIIn, g T _floor , ° C PE yield, g Activity, kg / mol _cat · MPa · h Polymer properties [η], dl / g M _v , 10 ^-3 Mp. ° C CH ₃ 1000 s 8 N-hexane 0.1956 fifty 10.8 17400 7.48 1074.0 141.8 2.2 nine N-heptane 0.2333 70 23.5 31700 4.9 571.5 140.3 2.7 10* N-hexane 0.2161 70 20,4 29694 2.64 261.0 138.0 2.9 eleven** N-gasoline 0.1763 80 6.2 11051 3.8 394.0 140.0 4,5 * Socialization - Al (i-C ₄ H ₉ ) ₃ ; Al / Fe (IIIH) = 100: 1. ** p _e = 0.1 MPa.

Example 12

Synthesis of supported IVn catalyst on a binary mixture of I and II catalysts (first option).

The synthesis is carried out under the conditions of synthesis of catalyst IIIn, but is applied to SMAO (1.0 g) 0.2 mg I and 2.2 mg II.

1 g of supported catalyst contains 3 · 10 ^-7 mol of I and 2.85 · 10 ^-6 mol of II, i.e. χ _Fe = 0.10; χ _Ni = 0.90.

Examples 13-14.

Polymerization of ethylene on a catalyst IVn.

The polymerization is carried out on the catalyst IVn in example 6, but under the conditions shown in table 2. The results obtained are also shown in table 2.

table 2 No. pr. The amount of IVn, g T _floor ° C Yield, g

Polymer properties [η], dl / g M _v · 10 ⁻³ Mp. ° C Δ N, J / g

thirteen 0.2000 fifty 3,5 18518 4.8 560.0 130.6 137.4 12,2 14 0.1542 70 4.3 29861 6.0 773.0 110; 130.8 120.0 19.5

Example 15

Synthesis of supported catalyst v _H on a binary mixture of catalysts I and II (second option).

5.28 mg of I in 8 ml of toluene is added to 1.38 g of SMAO and, over a period of 1 h, in an inert atmosphere at t _room temperature, it is applied to the substrate with constant stirring. Then, at t _room, toluene is evacuated, the mixture is cooled to 0 ° C, 5.6 mg of II in 8.0 ml of toluene is added, and II is continued to be applied at 0 ° C for 1 hour. After the application time has elapsed, again evacuation at t _room toluene is removed, then at 0 ° C. 0.3 ml of a 10% solution of MAO in toluene (0.026 g) and 8 ml of n-hexane are added. The mixture was stirred at 0 ° C for 1 h. Drying of the catalyst v _{H was} carried out in vacuo at t _room with stirring to constant weight.

1 g of supported catalyst contains 1.08 · 10 ^-5 moles of a mixture of catalysts I and II. Σ MAO / Σ cat = 520: 1, mol / mol, where χ _Fe = 0.51; χ _Ni = 0.49.

Example 16-17.

Polymerization of ethylene on a v _H catalyst.

The polymerization is carried out as in example 4, but under the conditions given in table 3. The results obtained are also reflected in table 3.

Table 3. No. pr. The amount of Vn, g T _floor. ° C R _e MPa Yield, g

Polymer properties [η], dl / g M _v · 10 ⁻³ Mp. ° C Δ N, J / g

16 0.1786 70 0.5 5.8 6105.0 4.17 440.0 134.0 114.0 15.0 17 * 0.1617 70 1,0 15.7 9235.0 4.42 490.0 135.0 69.2 11.2 * The solvent is n-heptane.

Example 18

Synthesis of supported catalyst VIn on a binary mixture of catalysts I and II (second option).

The synthesis is carried out under conditions of obtaining Vn catalyst, but catalyst II (5.0 mg) is applied first on SMAO (1.23 g), and only then I (deposition conditions II and I are described in the synthesis of Vn catalyst).

1 g of supported catalyst contains 1.06 · 10 ^-5 moles of binary catalyst I and II. MAO / Σ cat = 534: 1; χ _Fe = 0.50; χ _Ni = 0.50.

Examples 19-21.

Polymerization of ethylene on a VIn catalyst.

The polymerization is carried out according to example 4, but under the conditions given in table 4, which also reflects the results.

Example 22

Synthesis of supported vIIn catalyst on a binary mixture of In and IIn catalysts (third option).

The synthesis is carried out by mixing the individual supported catalysts IH and IIH, obtained on the basis of catalysts I and II (examples 3 and 5). Mixing is carried out before each polymerization in one ampoule.

Examples 23-27.

Polymerization of ethylene on a catalyst VIIn.

The polymerization is carried out as in example 4, but under the conditions given in table 5. This table also shows the results.

When comparing the results obtained during the polymerization of ethylene on two-component supported catalysts synthesized by three variants of the method, the following points can be noted:

1. The highest activity was found for the catalysts obtained according to the first and third version of the deposition method (IIIn and VIIn catalysts). Moreover, for systems obtained using the third variant of the application method (VIIn), the polymer yield is higher than the total (additive) yield obtained on the individual components of the mixture of the catalysts Iн and IIн. This result indicates that in a binary mixture one catalytic component enhances another.

2. Regardless of the method of deposition of the catalysts, it is possible to control the short chain branching of the obtained polyethylenes. The greatest branching was obtained in experiments when the specific content of complex II on the support surface was χ _Ni = 0.8-0.9, and high activity was maintained on IVn and VIIn catalysts, despite a small fraction of the more active component of the catalyst.

3. With an increase in the polymerization temperature to 80 ° C, the activity of both the catalysts and the MM of the resulting polymers remain at a high level.

Claims (7)

1. A two-component supported ethylene polymerization catalyst, comprising a mixture of transition metal complexes, alumoxane and a substrate, characterized in that the catalyst contains bis (imino) pyridyl complex of iron chloride and a bis (imino) acenaphthyl bromide complex as transition metal complexes nickel. 2. The two-component supported catalyst according to claim 1, characterized in that the ratio of molar fractions of iron to molar fractions of nickel is 1: 1-1: 9. 3. The two-component supported catalyst according to claims 1 and 2, characterized in that it contains silicon dioxide as a substrate. 4. A method of preparing a two-component supported ethylene polymerization catalyst, characterized in that it is prepared by applying to silicon dioxide a homogeneous mixture of transition metal complexes, such as a bis (imino) pyridyl complex of iron chloride and a bis (imino) acenaphthyl nickel bromide complex. 5. A method of preparing a two-component supported ethylene polymerization catalyst, characterized in that the bis (imino) pyridyl complex of iron chloride is alternately applied to silicon dioxide, then the bis (imino) acenaphthyl complex of nickel bromide or vice versa. 6. A method of preparing a two-component supported ethylene polymerization catalyst, characterized in that it is prepared by mixing individually deposited on silica complexes, namely a bis (imino) pyridyl complex of iron chloride and a bis (imino) acenaphthyl complex of nickel bromide. 7. A method of producing polyethylene, characterized in that the polymerization process is carried out in the presence of a catalyst according to any one of claims 1 to 3.