Catalyst, preparation method thereof and application of catalyst in synthesis of difluoroacetyl fluoride

Abstract

The invention provides a catalyst as well as a preparation method and application thereof in synthesis of difluoroacetyl fluoride, and the method comprises the following steps: adding an alcoholic solution of HF into an alcoholic solution of gamma-Al2O3 for reaction, then standing for aging, drying to remove an alcohol solvent, and roasting at high temperature in an inert atmosphere to obtain an AlF3 / gamma-Al2O3 catalyst. The method is simple in reaction process, easy to operate, simple, efficient, low in reaction equipment requirement, good in process stability, easy in raw material obtaining, low in production cost, remarkable in economic value, environmentally friendly and easy to realize industrial production.

Description

Technical Field

[0001] The invention relates to the technical field of catalysts, and in particular to a catalyst and a preparation method thereof and application thereof in synthesizing difluoroacetyl fluoride. Background Art

[0002] Difluoroacetyl fluoride is a very important fluorine-containing fine chemical. It can be prepared into difluoroacetic acid alkyl ester intermediates through simple hydrolysis and esterification methods. Difluoroacetic acid alkyl esters are important chemical raw materials for the synthesis of medicines and pesticides, and are widely used in this field. There are many methods for preparing difluoroacetyl fluoride. Among them, the most industrially valuable synthesis route is to use tetrafluoroethylene (C2F4) and straight-chain alkanol (methanol or ethanol) as the initial raw materials, and then synthesize hydrofluoroethers through catalytic addition etherification. The hydrofluoroethers are then synthesized into difluoroacetyl fluoride through catalytic cracking. The synthesis route is as follows: .

[0003] In the process of synthesizing difluoroacetyl fluoride using hydrofluoroether as raw material, catalyst plays an important role. Finding green, cheap and efficient catalyst can not only improve the conversion rate and selectivity of the reaction, but also facilitate the realization of industrial production.

[0004] Chinese patent CN106831406A introduces a method and device for preparing difluoroacetyl fluoride using a non-metallic catalyst. The catalyst used is nitrogen-doped activated carbon. The activated carbon is used as a carrier, and is fully impregnated in a nitrogen-containing compound solution such as urea. After desolventization and drying, high-temperature carbonization is performed in a nitrogen atmosphere to obtain a nitrogen-doped activated carbon catalyst. The catalyst is used to synthesize difluoroacetyl fluoride by gas-phase catalytic cracking of 1,1,2,2-tetrafluoroethyl ether. The reaction temperature is 220°C and the reaction space velocity is 130 h-1. The reaction generates difluoroacetyl fluoride with a conversion rate of 36.1% and a selectivity of 98.7%. Although the preparation process of the nitrogen-doped activated carbon catalyst is simple and the cost is low, the reaction conversion rate is not high and it is not easy to industrialize.

[0005] Chinese patent CN107867997A discloses a method for preparing difluoroacetyl fluoride by catalytic cracking of 1,1,2,2-tetrafluoroethyl methyl ether as a raw material, wherein the catalyst used is AlF3, and the preparation process is to use an organic aluminum solution to contact with an ether solution of HF for reaction, and then use a fluorination agent to perform fluorination treatment and roasting treatment at high temperature after static aging, desolvation, and drying to obtain an aluminum fluoride catalyst. In the reaction of catalytic cracking of 1,1,2,2-tetrafluoroethyl methyl ether to synthesize difluoroacetyl fluoride, although the catalyst has a high catalytic activity, the preparation process is complicated, using an organic aluminum raw material and a fluorination agent, and at the same time, a large amount of waste gas generated by it must be harmlessly treated, which makes the preparation cost of the catalyst high and difficult to industrialize.

[0006] In summary, the preparation of difluoroacetyl fluoride by catalytic cracking of 1,1,2,2-tetrafluoroethyl alkyl ether is easy to achieve, but the preparation of the catalyst is a difficult problem. The preparation process of the efficient catalyst is complicated and costly, while the catalyst activity is low when the preparation process is simple. Therefore, it is necessary to further develop a green, efficient and inexpensive method to prepare efficient catalysts. Summary of the invention

[0007] The present invention aims to solve one of the technical problems in the prior art at least to a certain extent. To this end, an object of the present invention is to provide a catalyst and a preparation method thereof and an application thereof in the synthesis of difluoroacetyl fluoride.

[0008] In a first aspect of the present invention, the present invention provides a method for preparing a catalyst, the method comprising: The alcohol solution of HF is added to the alcohol solution of γ-Al2O3 for reaction, and then the mixture is allowed to stand for aging. After drying to remove the alcohol solvent, the mixture is calcined at high temperature in an inert atmosphere to obtain an AlF3 / γ-Al2O3 catalyst.

[0009] According to the preparation method of the above-mentioned catalyst of the present invention, HF is dissolved in an alcohol solution and slowly added dropwise to the alcohol solution of γ-Al2O3. In the above-mentioned alcohol solution system, the catalyst prepared by the reaction of γ-Al2O3 with HF has more active sites and higher activity of the catalyst. In the above-mentioned alcohol solvent system, γ-Al2O3 and HF can fully react, and it is easy to obtain a highly active catalyst, avoiding the problem that the prior art uses γ-Al2O3 and gas phase HF to prepare AlF3 catalysts, which requires multiple fluorinations and harsh reaction conditions. At the same time, the entire contact reaction process of γ-Al2O3 and HF can be carried out at room temperature, with low environmental requirements for the reaction, high applicability, and simple operation. Then, by standing and aging, γ-Al2O3 and HF are fully reacted, so that the obtained active material AlF3 and γ-Al2O3 are fully contacted to form a stable catalyst structure with high activity. Finally, the alcohol solvent is removed and dried, and high-temperature roasting is carried out under an inert atmosphere to obtain a catalyst loaded with AlF3 of γ-Al2O3. The method for preparing the catalyst AlF3 / γ-Al2O3 has the advantages of simple reaction process, easy operation, simplicity and high efficiency, low requirements for reaction equipment, good process stability, easy availability of raw materials, low production cost, significant economic value, green and environmental protection, and easy to realize industrial production.

[0010] It should be noted that the present invention does not particularly limit the HF concentration in the HF alcohol solution and the γ-Al2O3 concentration in the γ-Al2O3 alcohol solution. When the HF concentration in the HF alcohol solution is relatively high, the dropping speed is reduced during dropwise addition. When the HF concentration in the HF alcohol solution is relatively low, the dropping speed is increased during dropwise addition. Those skilled in the art can select the concentration and dropping speed according to actual conditions.

[0011] According to the preparation method of the above catalyst of the present invention, the molar ratio of the γ-Al2O3 to the HF is (200-1.5):1, preferably (150-20):1. For example, the molar ratio of γ-Al2O3 to HF is 200:1, 180:1, 150:1, 130:1, 100:1, 80:1, 30:1, 10:1, 5:1, 1.5:1, etc., or a range between any two of the above values. When the molar ratio of γ-Al2O3 to HF is within the above range, especially within the range of (150-20):1, the prepared catalyst has excellent catalytic performance, high conversion rate of the catalyst in the synthesis of difluoroacetyl fluoride, and good selectivity.

[0012] According to the preparation method of the catalyst of the present invention, the alcohol in the alcohol solution includes at least one of methanol, ethanol and propanol, preferably ethanol. By adopting the alcohol solution, the catalyst preparation process is stable, efficient, simple, and the prepared catalyst has high activity and good stability.

[0013] According to the preparation method of the catalyst of the present invention, the static aging time is 2 h to 5 h. The static aging time is 2 h, 3 h, 4 h, 5 h, etc., or a range between any two of the above values.

[0014] According to the method for preparing the catalyst of the present invention, the drying temperature is 110° C. to 150° C., and the drying time is 8 h to 12 h.

[0015] According to the preparation method of the catalyst of the present invention, the temperature of the high temperature roasting is 300°C to 500°C, and the time is 3 h to 5 h. For example, the temperature of the high temperature roasting is 300°C, 350°C, 400°C, 450°C, 500°C, etc., or the range between any two of the above values; the time is 3 h, 3.5 h, 4 h, 4.5 h, 5 h, etc., or the range between any two of the above values.

[0016] In a second aspect of the present invention, a catalyst is provided. The catalyst is prepared by the above method. The catalyst has high catalytic activity, high conversion rate, good catalyst stability and few by-products of difluoroacetyl fluoride in the catalytic synthesis of difluoroacetyl fluoride.

[0017] According to the above catalyst of the present invention, in the AlF3 / γ-Al2O3 catalyst, the mass fraction of AlF3 is 0.18% to 7.6%, preferably 0.2% to 2%. For example, the mass fraction of AlF3 is 0.18%, 0.2%, 0.5%, 0.8%, 1.0%, 1.2%, 1.5%, 1.8%, 2.0%, 3%, 4%, 5%, 6%, 7%, 7.6%, or the range between any two of the above values. The above AlF3 / γ-Al2O3 catalyst has high catalytic activity, high conversion rate and good selectivity.

[0018] In the third aspect of the present invention, the present invention proposes the use of the above catalyst in the synthesis of difluoroacetyl fluoride.

[0019] According to the above application of the present invention, hydrofluoroether is used as a raw material to synthesize difluoroacetyl fluoride under the action of the catalyst, the catalytic reaction temperature is 180°C to 250°C, and the flow rate of the hydrofluoroether atmosphere is controlled to maintain a reaction space velocity of 100 h -1 ~1000 h -1 .

[0020] The present invention has at least the following technical effects: The method for preparing the catalyst AlF3 / γ-Al2O3 has a simple reaction process, is easy to operate, is concise and efficient, has low requirements for reaction equipment, has good process stability, is easy to obtain raw materials, has low production cost, has significant economic value, is green and environmentally friendly, and is easy to achieve industrial production. In addition, the catalyst has high catalytic activity, high conversion rate, good catalyst stability, and less byproducts of the obtained difluoroacetyl fluoride in the catalytic synthesis of difluoroacetyl fluoride. DETAILED DESCRIPTION

[0021] Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. The present invention is described below with reference to specific embodiments. It should be noted that these embodiments are merely illustrative and do not limit the present invention in any way.

[0022] Example 1 The preparation process of the AlF3 / γ-Al2O3 catalyst of this embodiment is as follows: Take 80.0 g of γ-Al2O3 and stir and disperse it in 100 ml of anhydrous ethanol, then slowly drop anhydrous ethanol solution containing 5.2 g of HF into it for reaction (the molar ratio of γ-Al2O3:HF is 3:1). After the addition is completed, continue the reaction for 1 h, then stop stirring, let it stand for aging for 12 h, filter, dry, and then activate it at 500 ° C in a nitrogen atmosphere for 3 h to obtain AlF3 catalyst, recorded as AlF3 / γ-Al2O3-1. 20 ml of the above catalyst was loaded into a stainless steel tubular reactor (φ20×500 mm), replaced with nitrogen, heated the reactor to 220 ° C, and introduced gas phase 1,1,2,2-tetrafluoroethyl ethyl ether for reaction, and the reaction space velocity was controlled to 300h -1 .

[0023] Example 2 The preparation process of the AlF3 / γ-Al2O3 catalyst of this embodiment is as follows: Take 80.0 g of γ-Al2O3 and stir and disperse it in 100 ml of anhydrous ethanol, then slowly drop anhydrous ethanol solution containing 2.6 g of HF into it for reaction (the molar ratio of γ-Al2O3:HF is 6:1). After the addition is completed, continue the reaction for 1 h, then stop stirring, let it stand for aging for 12 h, filter, dry, and then activate it at 500 ° C in a nitrogen atmosphere for 3 h to obtain AlF3 catalyst, recorded as AlF3 / γ-Al2O3-2. 20 ml of the above catalyst was loaded into a stainless steel tubular reactor (φ20×500 mm), replaced with nitrogen, heated the reactor to 220 ° C, and introduced gas phase 1,1,2,2-tetrafluoroethyl ethyl ether for reaction, and the reaction space velocity was controlled to 300h -1 .

[0024] Example 3 The preparation process of the AlF3 / γ-Al2O3 catalyst of this embodiment is as follows: Take 80.0 g of γ-Al2O3 and stir and disperse it in 100 ml of anhydrous ethanol, then slowly drop anhydrous ethanol solution containing 1.0 g of HF into it for reaction (the molar ratio of γ-Al2O3:HF is 15:1). After the addition is completed, continue the reaction for 1 h, then stop stirring, let it stand for aging for 12 h, filter, dry, and then activate it at 500°C in a nitrogen atmosphere for 3 h to obtain AlF3 catalyst, recorded as AlF3 / γ-Al2O3-3. 20 ml of the above catalyst was loaded into a stainless steel tubular reactor (φ20×500 mm), replaced with nitrogen, heated the reactor to 220°C, and introduced gas phase 1,1,2,2-tetrafluoroethyl ethyl ether for reaction, and the reaction space velocity was controlled to be 300h -1 .

[0025] Example 4 The preparation process of the AlF3 / γ-Al2O3 catalyst of this embodiment is as follows: Take 80.0 g of γ-Al2O3 and stir and disperse it in 100 ml of anhydrous ethanol, then slowly drop anhydrous ethanol solution containing 0.52 g of HF into it for reaction (the molar ratio of γ-Al2O3:HF is 30:1). After the addition is completed, continue the reaction for 1 h, then stop stirring, let it stand for aging for 12 h, filter, dry, and then activate it at 500°C in a nitrogen atmosphere for 3 h to obtain AlF3 catalyst, recorded as AlF3 / γ-Al2O3-4. 20 ml of the above catalyst was loaded into a stainless steel tubular reactor (φ20×500 mm), replaced with nitrogen, heated the reactor to 220°C, and introduced gas phase 1,1,2,2-tetrafluoroethyl ethyl ether for reaction, and the reaction space velocity was controlled to be 300h -1 .

[0026] Example 5 The preparation process of the AlF3 / γ-Al2O3 catalyst of this embodiment is as follows: Take 80.0 g of γ-Al2O3 and stir and disperse it in 100 ml of anhydrous ethanol, then slowly drop anhydrous ethanol solution containing 0.26 g of HF into it for reaction (the molar ratio of γ-Al2O3:HF is 60:1). After the addition is completed, continue the reaction for 1 h, then stop stirring, let it stand for aging for 12 h, filter, dry, and then activate it at 500°C in a nitrogen atmosphere for 3 h to obtain AlF3 catalyst, recorded as AlF3 / γ-Al2O3-5. 20 ml of the above catalyst was loaded into a stainless steel tubular reactor (φ20×500 mm), replaced with nitrogen, heated the reactor to 220°C, and introduced gas phase 1,1,2,2-tetrafluoroethyl ethyl ether for reaction, and the reaction space velocity was controlled to be 300h -1 .

[0027] Example 6 The preparation process of the AlF3 / γ-Al2O3 catalyst of this embodiment is as follows: Take 80.0 g of γ-Al2O3 and stir and disperse it in 100 ml of anhydrous ethanol, then slowly drop anhydrous ethanol solution containing 0.16 g of HF into it for reaction (the molar ratio of γ-Al2O3:HF is 100:1). After the addition is completed, continue the reaction for 1 h, then stop stirring, let it stand for aging for 12 h, filter, dry, and then activate it at 500 ° C in a nitrogen atmosphere for 3 h to obtain AlF3 catalyst, recorded as AlF3 / γ-Al2O3-6. 20 ml of the above catalyst was loaded into a stainless steel tubular reactor (φ20×500 mm), replaced with nitrogen, heated the reactor to 220 ° C, and introduced gas phase 1,1,2,2-tetrafluoroethyl ethyl ether for reaction, and the reaction space velocity was controlled to 300h -1 .

[0028] Example 7 The preparation process of the AlF3 / γ-Al2O3 catalyst of this embodiment is as follows: Take 80.0 g of γ-Al2O3 and stir and disperse it in 100 ml of anhydrous ethanol, then slowly drop anhydrous ethanol solution containing 0.11 g of HF into it for reaction (the molar ratio of γ-Al2O3:HF is 150:1). After the addition is completed, continue the reaction for 1 h, then stop stirring, let it stand for aging for 12 h, filter, dry, and then activate it at 500°C in a nitrogen atmosphere for 3 h to obtain AlF3 catalyst, recorded as AlF3 / γ-Al2O3-7. 20 ml of the above catalyst was loaded into a stainless steel tubular reactor (φ20×500 mm), replaced with nitrogen, heated the reactor to 220°C, and introduced gas phase 1,1,2,2-tetrafluoroethyl ethyl ether for reaction, and the reaction space velocity was controlled to be 300h -1 .

[0029] Example 8 The difference between Example 8 and Example 4 is: Except for the calcination activation reaction at 400°C, the other process parameters and operation methods remain unchanged.

[0030] Example 9 The difference between Example 9 and Example 4 is as follows: Except for the calcination activation reaction at 300°C, the other process parameters and operation methods remain unchanged.

[0031] Example 10 The difference between Example 10 and Example 4 is as follows: Except for the calcination activation time of 4 h, the other process parameters and operation methods remained unchanged.

[0032] Embodiment 11 The difference between Example 11 and Example 4 is as follows: Except for the calcination activation time of 5 h, the other process parameters and operation methods remained unchanged.

[0033] In the above examples, hydrofluoroether was used as raw material to synthesize difluoroacetyl fluoride under the action of a catalyst. The catalytic cracking products of the above examples were absorbed by ethanol and then converted into difluoroacetic acid ethyl ester samples, which were quantitatively analyzed using a gas chromatograph. See Table 1 for details.

[0034] Table 1

[0035] As shown in Table 1, the catalyst of the present application has excellent catalytic activity, especially when the catalyst is prepared by using a suitable γ-Al2O3:HF molar ratio, and catalytic cracking is used to synthesize difluoroacetyl fluoride, a higher conversion rate and selectivity can be obtained.

[0036] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a catalyst, characterized in that: include: The alcohol solution of HF is added to the alcohol solution of γ-Al2O3 for reaction, and then the mixture is allowed to stand for aging. After drying to remove the alcohol solvent, the mixture is calcined at high temperature in an inert atmosphere to obtain an AlF3 / γ-Al2O3 catalyst.

2. The method according to claim 1, characterized in that: The molar ratio of the γ-Al2O3 to the HF is (200-1.5):1, preferably (150-20):

1.

3. The method according to claim 1 or 2, characterized in that: The alcohol in the alcohol solution includes at least one of methanol, ethanol and propanol, preferably ethanol.

4. The method according to claim 1 or 2, characterized in that: The static aging time is 2 h to 5 h.

5. The method according to claim 1 or 2, characterized in that: The drying temperature is 110° C. to 150° C., and the drying time is 8 h to 12 h.

6. The method according to claim 1 or 2, characterized in that: The high temperature calcination is carried out at a temperature of 300° C. to 500° C. and for a time of 3 h to 5 h.

7. A catalyst, characterized in that The method is prepared by any one of claims 1 to 6.

8. The catalyst according to claim 7, characterized in that In the AlF3 / γ-Al2O3 catalyst, the mass fraction of AlF3 is 0.18%~7.6%, preferably 0.2%~2%.

9. Use of the catalyst according to claim 7 or 8 in the synthesis of difluoroacetyl fluoride.

10. The use according to claim 9, characterized in that: Using hydrofluoroether as a raw material, synthesizing the difluoroacetyl fluoride under the action of the catalyst; The temperature of the catalytic reaction is 180℃~250℃; The flow rate of the hydrofluoroether atmosphere was controlled to maintain a reaction space velocity of 100 h -1 ~1000 h -1 .

Images