Iron-aluminum-based catalyst and application thereof in synthesis of trimethylaluminum

Abstract

The invention relates to an iron-aluminum-based catalyst and an application thereof in synthesis of trimethylaluminum, and the iron-aluminum-based catalyst is mainly prepared by the following steps: under a protective atmosphere, adding an iron salt and an aluminum salt into a reaction furnace, heating for melting, cooling, and grinding to obtain the iron-aluminum-based catalyst. The application of the iron-aluminum-based catalyst in synthesis of trimethylaluminum comprises the following steps: under a protective atmosphere, adding the iron-aluminum-based catalyst and trialkylaluminum into an inert solvent in a closed normal-pressure reaction kettle, starting heating and stirring, simultaneously and continuously introducing halomethane for reaction, after the reaction is finished, cooling, standing and filtering, and under the protective atmosphere, distilling filtrate to obtain the trimethylaluminum. The trimethyl aluminum is obtained. The iron-aluminum-based catalyst is wide in raw material source, low in cost and high in catalytic efficiency.

Description

Technical Field

[0001] The invention belongs to the technical field of metal organic compounds, and relates to a catalyst and a method for synthesizing trimethylaluminum, and specifically to an iron-aluminum-based catalyst and application thereof in synthesizing trimethylaluminum. Background Art

[0002] Trimethylaluminum (TMA) is mainly used as an olefin polymerization catalyst, ignition fuel, and is also used to prepare straight-chain primary alcohols and olefins. It can also be used for metal organic compound vapor deposition and is an important organometallic compound. There are many methods for preparing trimethylaluminum, but few can actually be used industrially. The common method is to use industrial triethylaluminum and alkyl halides for alkyl exchange reaction.

[0003] CN109942611A discloses a method for preparing trimethylaluminum, comprising: step I, in the presence of a bismuth-based compound and a solvent, trialkylaluminum and methyl halide react to obtain a reaction product; step II, removing the halogenated alkane in the reaction product, then leaving the reaction product to stand to precipitate crystals, recovering the precipitated crystals and separating the remaining reaction product to obtain trimethylaluminum. However, the reaction requires the use of a rare metal bismuth compound as a catalyst, which is relatively costly; although the conversion rate of triethylaluminum obtained by the method can reach 99.0%, the loss rate of Bi is greater than 10%, and the catalyst loss is relatively large, which is not only not conducive to the recycling and treatment of the reaction solution, but also causes a large amount of catalyst loss and deactivation. In addition, the reaction adopts an autoclave and a high-pressure process, which increases the investment cost and safety risks.

[0004] CN1229797A discloses a method for synthesizing hydrocarbyl aluminum, wherein hydrocarbyl aluminum is prepared by reacting an iron-based or iron-antimony-based compound with an organic aluminum compound and a halogenated hydrocarbon. However, when hydrocarbyl aluminum is prepared by reacting an iron-based compound with an organic aluminum compound and a halogenated hydrocarbon, the reaction yield based on triethyl aluminum is only 63.3% at the lowest and 92.0% at the highest. When hydrocarbyl aluminum is prepared by reacting an iron-antimony-based compound with an organic aluminum compound and a halogenated hydrocarbon, the reaction yield based on triethyl aluminum is only 61.8% at the lowest and 70.4% at the highest. The reaction yield of triethyl aluminum is not high, the price of antimony is high, the cost accounts for a large proportion, and the loss and reuse of the catalyst are not disclosed.

[0005] In summary, it is urgent to find an iron-aluminum-based catalyst with a wide source of raw materials, low cost, high catalytic efficiency and low loss rate, as well as a method for synthesizing trimethylaluminum with simple process, small catalyst dosage, low catalytic temperature, short reaction time, high conversion rate of trialkylaluminum, good stability and high repeatability. Summary of the invention

[0006] The technical problem to be solved by the present invention is to overcome the above-mentioned defects of the prior art and provide a method for synthesizing an iron-aluminum-based catalyst with a wide source of raw materials, low cost, high catalytic efficiency and low loss rate.

[0007] The technical problem further to be solved by the present invention is to overcome the above-mentioned defects of the prior art and provide a method for synthesizing trimethylaluminum with simple process, small amount of catalyst, low catalytic temperature, short reaction time, high conversion rate of alkyl aluminum, good stability and high repeatability.

[0008] The technical solution adopted by the present invention to solve the technical problem is as follows: The present invention provides an iron-aluminum-based catalyst, which is composed of an iron salt and an aluminum salt, wherein the molar ratio of the iron element to the aluminum element is (1-5):1, and the particle size is 10-80 μm. The iron salt and the aluminum salt are added into a reaction furnace under a protective atmosphere, heated to melt, cooled, and ground to obtain the catalyst.

[0009] The molar ratio of the iron element in the iron salt to the aluminum element in the aluminum salt in the iron-aluminum-based catalyst of the present invention is (1-5):1.

[0010] The heating and melting process is as follows: heating to 180-800°C at a rate of 1-60°C / min, preferably 3-20°C / min; maintaining the pressure at 0.1-1MPa for 3-6h, preferably maintaining the pressure at 0.5-1MPa for 4h.

[0011] The cooling refers to cooling to room temperature at a rate of 1 to 60°C / min, preferably 2 to 10°C / min; the grinding refers to grinding to a particle size of 10 to 80 μm.

[0012] The protective atmosphere includes nitrogen, argon or helium; the iron salt includes ferric chloride or ferric sulfate, and hydrates thereof; the aluminum salt includes aluminum chloride, aluminum sulfate, and hydrates thereof.

[0013] The present invention also provides the use of an iron-aluminum-based catalyst in the synthesis of trimethylaluminum, specifically, under a protective atmosphere, the iron-aluminum-based catalyst and trialkylaluminum are added to an inert solvent in a closed atmospheric pressure reactor, heated and stirred for reaction, and methyl halide is continuously introduced at the same time, the temperature is reduced, the mixture is allowed to stand, and filtered. Under a protective atmosphere, the filtrate is distilled to obtain trimethylaluminum.

[0014] The molar ratio of the iron-aluminum-based catalyst, trialkylaluminum, inert solvent and methyl halide is (0.03-0.15):1:(0.4-0.6):(3-10); the trialkylaluminum is R3Al, R is C2-C 10 Alkyl, R3Al includes, but is not limited to, triethylaluminum, tripropylaluminum, tri-n-butylaluminum, triisobutylaluminum, dimethylethylaluminum or methyldiethylaluminum.

[0015] The inert solvent is a saturated alkane or aromatic hydrocarbon, which is C8-C20, including but not limited to octane, decane, tetralin, and hexadecane; the heating and stirring reaction, and the continuous introduction of methyl halide at the same time means: under normal pressure and stirring, the temperature is raised to 100-150° C., and then the methyl halide is continuously introduced, and the reaction is stirred and kept warm for 3-7 hours; the methyl halide includes methyl chloride, methyl bromide or methyl iodide.

[0016] The cooling refers to cooling to room temperature; the standing time is 0.5 to 3.0 hours; the distillation pressure is -99KPa to 2kPa, the temperature is 30 to 140°C, and the reflux ratio is 0.5 to 5.0; the protective atmosphere includes nitrogen, argon or helium.

[0017] The beneficial effects of the present invention are as follows: (1) The raw materials of the iron-aluminum-based catalyst of the present invention are widely available, low in cost, high in catalytic efficiency, and the loss rate is as low as 0.1-2.0%; (2) The method of the present invention has a simple process, a small amount of catalyst, a low catalytic temperature, a short reaction time, and a conversion rate of trialkyl aluminum as high as 98.6%, indicating that the catalytic conversion of the iron-aluminum-based catalyst of the present invention has good stability; after the iron-aluminum-based catalyst is recycled for 10 times, the conversion rate of trialkyl aluminum can still be as high as 93.9%, indicating that the catalytic conversion of the iron-aluminum-based catalyst of the present invention has high repeatability. DETAILED DESCRIPTION

[0018] The present invention will be further described below in conjunction with the embodiments.

[0019] The nitrogen used in the present invention is a high-purity gas with a purity of ≥99.9%; the raw materials or chemical reagents used in the embodiments of the present invention, unless otherwise specified, are obtained through conventional commercial channels.

[0020] Iron-aluminum-based catalyst Example 1 The iron-aluminum-based catalyst is prepared by the following method: under a high-purity nitrogen atmosphere, 162.204g of ferric chloride and 133.34g of aluminum chloride are added into a reaction furnace, and the temperature is raised to 200°C at a rate of 10°C / min at a pressure of 0.6Mpa, and maintained for 3 hours until melting, and then cooled to room temperature at a rate of 1°C / min, and ground to a particle size of 10 to 80μm, to obtain 295.544g of iron-aluminum-based catalyst 1 (FeCl3-AlCl3).

[0021] Iron-aluminum-based catalyst Example 2 The iron-aluminum-based catalyst is prepared by the following method: under a high-purity nitrogen atmosphere, 399.878 g of ferric sulfate and 89.3378 g of aluminum chloride are added into a reaction furnace, and the temperature is raised to 190° C. at a rate of 3° C. / min at a pressure of 0.4 MPa, and maintained for 6 hours. After confirming melting, the temperature is lowered to room temperature at a rate of 2° C. / min, and the catalyst is ground to a particle size of 10 to 80 μm to obtain 489.2158 g (1.0 mol) of the iron-aluminum-based catalyst 2 (Fe2(SO4)3-0.67AlCl3).

[0022] Iron-aluminum-based catalyst Example 3 The iron-aluminum-based catalyst is prepared by the following method: under a high-purity nitrogen atmosphere, 162.204 g (1.0 mol) of ferric chloride and 34.2151 g (0.1 mol) of aluminum sulfate are added into a reaction furnace, and the temperature is raised to 330° C. at a speed of 60° C. / min under a pressure of 0.6 MPa, and the temperature is maintained for 10 hours for melting, and then the temperature is lowered to room temperature at a speed of 3° C. / min, and the catalyst is ground to a particle size of 10 to 80 μm to obtain 276.1 g (1.0 mol) of the iron-aluminum-based catalyst 3 (FeCl3-0.1Al2(SO4)3).

[0023] Method for synthesizing trimethylaluminum Examples 1-1 to 1-3 In a high-purity nitrogen atmosphere, 44.3 g of Fe-Al-based catalyst 1, 73.4 g of Fe-Al-based catalyst 2, 41.4 g of Fe-Al-based catalyst 3, and 114.168 g of triethylaluminum were added to 56.9 g of In an inert solvent decane, at normal pressure and a stirring speed of 500 r / min, the temperature was raised to 115°C at a rate of 3°C / min, and then 284.814 g (3.0 mol) of methyl bromide was continuously introduced at a rate of 22.4 L / h, and the reaction was heated and stirred for 3 hours. The temperature was then lowered to room temperature at a rate of 2°C / min, and the mixture was allowed to stand for 0.5 hours. The mixture was filtered, and the filtrate was distilled in a high-purity nitrogen atmosphere at a pressure of 101.3 kPa, a temperature of 128°C, and a reflux ratio of 5.0 to obtain 65.5 g (0.908 mol), 65.2 g (0.904 mol), and 64.6 g (0.896 mol) of trimethylaluminum, respectively.

[0024] The filter cakes obtained by filtration were dried respectively, and 44.1 g of the iron-aluminum-based catalyst 1, 72.8 g of the iron-aluminum-based catalyst 2, and 41.3 g of the iron-aluminum-based catalyst 3 were recovered respectively, with weight losses of approximately 0.45%, 0.82%, and 0.24%, respectively.

[0025] A small amount of reaction liquid without catalyst was hydrolyzed with dilute hydrochloric acid solution, and the gas after hydrolysis was analyzed by gas chromatography to obtain the contents of methane and ethane, thereby calculating the conversion rates of triethylaluminum to be 95.7%, 95.2% and 94.3%, respectively.

[0026] Method for synthesizing trimethylaluminum Examples 2-1 to 2-3 In a high-purity nitrogen atmosphere, 32.5 g of iron-aluminum-based catalyst 1, 53.8 g of iron-aluminum-based catalyst 2, 30.4 g of iron-aluminum-based catalyst 3, and 156.249 g of tripropylaluminum were added to 71.1 g of inert solvent decane in a closed atmospheric pressure reactor, and the temperature was raised to 110°C at a rate of 2°C / min at atmospheric pressure and a stirring speed of 400 r / min. Then, 201.9 g (4.0 mol) of methyl chloride was continuously introduced at a rate of 22.4 L / h, and the mixture was heated and stirred for 4 h. The mixture was then cooled to room temperature at a rate of 2°C / min, allowed to stand for 1 h, filtered, and the filtrate was distilled in a high-purity nitrogen atmosphere at a pressure of -95 kPa and a reflux ratio of 4.0 to obtain 69.3 g (0.961 mol), 69.6 g (0.965 mol), and 69.1 g (0.958 mol) of trimethylaluminum, respectively.

[0027] The filter cakes obtained by filtration were dried respectively, and 32.1 g of the iron-aluminum-based catalyst 1, 53.0 g of the iron-aluminum-based catalyst 2, and 30.1 g of the iron-aluminum-based catalyst 3 were recovered respectively, with weight losses of approximately 1.23%, 1.49%, and 0.99%, respectively.

[0028] A small amount of reaction liquid without catalyst was hydrolyzed with dilute hydrochloric acid solution, and the gas after hydrolysis was analyzed by gas chromatography to obtain the contents of methane and propane, thereby calculating the tripropylaluminum conversion rates of 98.2%, 98.6% and 97.9%.

[0029] Method for synthesizing trimethylaluminum Examples 3-1 to 3-3 Under a high-purity argon atmosphere, 14.8g of iron-aluminum-based catalyst 1, 24.5g of iron-aluminum-based catalyst 2, 13.8g of iron-aluminum-based catalyst 3, and 198.331g of triisobutylaluminum were added to 85.4g of solvent decane in a closed atmospheric pressure reactor, and the temperature was raised to 120°C at a rate of 3°C / min at normal pressure and a stirring speed of 300r / min. Then, 709.695g of methyl iodide was continuously introduced at a rate of 18.6L / h, and the mixture was heated and stirred for 6h. The mixture was then cooled to room temperature at a rate of 3°C / min, allowed to stand for 3h, filtered, and the filtrate was distilled under a high-purity argon atmosphere at a pressure of 1kPa, a temperature of 130°C, and a reflux ratio of 2.0 to obtain 67.96g, 67.47g, and 68.03g of trimethylaluminum, respectively.

[0030] The filter cakes obtained by filtration were dried respectively, and 14.5 g of the iron-aluminum-based catalyst 1, 24.0 g of the iron-aluminum-based catalyst 2, and 13.5 g of the iron-aluminum-based catalyst 3 were recovered respectively, with weight losses of approximately 2.1%, 2.0%, and 2.2%, respectively.

[0031] A small amount of reaction liquid without catalyst was hydrolyzed with dilute hydrochloric acid solution, and the gas after hydrolysis was analyzed by gas chromatography to obtain the contents of methane and isobutane, thereby calculating the conversion rates of triisobutylaluminum to be 98.2%, 97.5% and 98.3%.

[0032] Method for synthesizing trimethylaluminum Example 4 The difference between this embodiment and method embodiment 1-1 is that the iron-aluminum-based catalyst 1 recovered in method embodiment 1-1 is repeatedly used to synthesize trimethylaluminum for a total of 10 times according to method embodiment 1-1, and 65.2 g (0.904 mol) of trimethylaluminum is obtained in the 10th time.

[0033] The filter cake obtained by filtration was dried to recover 38.0 g (0.12 mol) of the iron-aluminum-based catalyst 1, with a weight loss of about 14.2% relative to 44.3 g.

[0034] A small amount of reaction liquid without catalyst was hydrolyzed with dilute hydrochloric acid solution, and the gas after hydrolysis was analyzed by gas chromatography to obtain the content of methane and isobutane, thereby calculating the conversion rate of triethylaluminum to be 95.2%.

[0035] Method for synthesizing trimethylaluminum Example 5 The only difference between this embodiment and method embodiment 1-2 is that the iron-aluminum-based catalyst 2 recovered in method embodiment 1-2 is repeatedly used to synthesize trimethylaluminum 10 times according to method embodiment 1-2, and 64.7 g (0.897 mol) of trimethylaluminum is obtained in the 10th time.

[0036] The filter cake obtained by filtration was dried to recover 58.7 g (0.12 mol) of the iron-aluminum-based catalyst 2, with a weight loss of about 19.75% relative to 73.4 g.

[0037] A small amount of reaction liquid without catalyst was hydrolyzed with dilute hydrochloric acid solution, and the gas after hydrolysis was analyzed by gas chromatography to obtain the content of methane and isobutane, thereby calculating the conversion rate of triethylaluminum to be 94.9%.

[0038] Method for synthesizing trimethylaluminum Example 6 The difference between this embodiment and method embodiments 1-3 is that the iron-aluminum-based catalyst 3 recovered in method embodiment 1-3 is repeatedly used to synthesize trimethylaluminum 10 times according to method embodiments 1-3, and 65.0 g (0.90 mol) of trimethylaluminum is obtained in the 10th time.

[0039] The filter cake obtained by filtration was dried to recover 37.5 (0.118 mol) g of the iron-aluminum-based catalyst 3, which was a weight loss of about 9.4% relative to 41.4 g.

[0040] A small amount of reaction liquid without catalyst was hydrolyzed with dilute hydrochloric acid solution, and the gas after hydrolysis was analyzed by gas chromatography to obtain the content of methane and isobutane, thereby calculating the conversion rate of triethylaluminum to be 93.9%.

[0041] The embodiments of the present invention have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. Therefore, the scope of protection of the present invention should be subject to the scope of protection of the claims.

Claims

1. An iron-aluminum-based catalyst, characterized in that: The iron-aluminum-based catalyst is composed of iron salt and aluminum salt, the molar ratio of iron element to aluminum element is (1-5):1, and the particle size is 10-80 μm; under a protective atmosphere, the iron salt and aluminum salt are added into a reaction furnace, heated to melt, cooled, and ground to obtain the catalyst.

2. The preparation of the iron-aluminum-based catalyst according to claim 1, characterized in that: The molar ratio of the iron element in the iron salt to the aluminum element in the aluminum salt is (1-5):1; the heating and melting: heating to 180-800°C at a rate of 1-60°C / min, and maintaining for 3-10 hours at a pressure of 0.1-2MPa; the cooling refers to cooling to room temperature at a rate of 1-60°C / min; the grinding is grinding to a particle size of 10-80μm; the protective atmosphere includes nitrogen, argon or helium; the iron salt includes ferric chloride or ferric sulfate, and hydrates thereof; the aluminum salt includes aluminum chloride, aluminum sulfate, and hydrates thereof.

3. The preparation of the iron-aluminum-based catalyst according to claims 1 and 2, characterized in that: The heating and melting process is as follows: heating the temperature to 190-460° C. at a speed of 3-20° C. / min.

4. The preparation of the iron-aluminum-based catalyst according to claims 1 and 2, characterized in that: The cooling refers to cooling to room temperature at a speed of 2 to 10°C / min.

5. The use of the iron-aluminum-based catalyst in the synthesis of trimethylaluminum according to claim 1, characterized in that: Under a protective atmosphere, the iron-aluminum-based catalyst of any one of claims 1 to 4 and trialkylaluminum are added to an inert solvent in a closed atmospheric pressure reactor, heating and stirring are started, and methyl halide is continuously introduced to react. After the reaction is completed, the temperature is lowered, the mixture is allowed to stand, and the mixture is filtered. Under a protective atmosphere, the filtrate is distilled to obtain trimethylaluminum.

6. The use of the iron-aluminum-based catalyst in the synthesis of trimethylaluminum according to claim 5, characterized in that: The molar ratio of the iron-aluminum-based catalyst, trialkylaluminum, inert solvent and methyl halide is (0.03-0.15):1:(0.4-0.6):(3-10); the trialkylaluminum is R3Al, R is C2-C 10 Alkyl, R3Al includes but is not limited to triethylaluminum, tripropylaluminum, tri-n-butylaluminum, triisobutylaluminum, dimethylethylaluminum or methyldiethylaluminum; the inert solvent is a saturated alkane or aromatic hydrocarbon, which is C8-C20, including but not limited to octane, decane, tetralin, and hexadecane; the heating, stirring, and simultaneously continuously introducing methyl halide to react refers to: under normal pressure and stirring, heating to 100-150°C, continuously introducing methyl halide, and stirring and reacting at 100-150°C for 3-7h; the methyl halide includes methyl chloride, methyl bromide or methyl iodide.

7. The use of the iron-aluminum-based catalyst in the synthesis of trimethylaluminum according to claim 5, characterized in that: The cooling refers to cooling to room temperature; the standing time is 0.5 to 3.0 hours; the distillation pressure is -99 KPa to 2 kPa, and the reflux ratio is 0.5 to 5.0.