Catalyst, preparation method thereof, and application thereof in the preparation of heptafluoroisobutanol

Abstract

The present invention belongs to the field of fluorochemical industry, and particularly relates to a catalyst, a preparation method thereof and an application thereof in the preparation of heptafluoroisobutanol. The catalyst comprises a hydrogenation metal oxide and a stabilizing metal oxide; the hydrogenation metal oxide is one or at least two mixtures of oxides of Cu, Zn, Ni, Fe, and Cr; the stabilizing metal is one or at least two mixtures of oxides of Ba, Ca, Mg, Cd, and Pb; the catalyst prepared by the present invention can effectively improve the conversion rate and selectivity. By optimizing the conditions, the product has high purity and yield. This enables the product to be produced on a large scale, and it is inexpensive and easy to promote.

Description

Technical Field

[0001] The present invention belongs to the field of fluorochemical industry, and particularly relates to a catalyst, a preparation method thereof, and an application thereof in the preparation of heptafluoroisobutanol. Background Art

[0002] Heptafluoroisobutanol is a new type of fluorocarbon alcohol material, which can be used as an important intermediate for synthesizing new medicines, pesticides, fabric finishing agents, and fragrances. At the same time, it can also be used as an important organic solvent, and can also be used as a raw material or auxiliary agent for synthesizing new organic polymer materials, having great market prospects and development value.

[0003] At present, there are several methods for synthesizing heptafluorobutanol, but these methods have the disadvantages of using dangerous goods, high raw material prices, harsh reaction conditions, and being unsuitable for large-scale production. The research on heptafluoroisobutanol is still in its infancy, and there is no large-scale synthesis report on it, which seriously hinders the development of its downstream products and its further development in the fluorochemical industry. The main synthesis methods are as follows: 1.

[0005]

[0006] This method has high raw material prices and harsh reaction conditions. It will explode when encountering water during operation, and it is difficult to industrialize. 2.

[0008]

[0009] This method requires an anhydrous and carbon dioxide-free reaction. At the same time, the reaction selectivity and controllability are relatively poor, and it is easy to introduce many by-products, making it difficult to separate and purify. 3.

[0011]

[0012] This method involves the use of dangerous goods. The reaction requires anaerobic and high-temperature and high-pressure conditions, which are difficult to operate and have complex post-treatment, and it is not easy to industrialize the product. Summary of the Invention

[0013] The purpose of the present invention is to overcome the disadvantages in the prior art and provide a preparation method of heptafluoroisobutanol.

[0014] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0015] A catalyst includes a hydrogenation metal oxide and a stabilizing metal oxide; the hydrogenation metal oxide is one or a mixture of at least two of the metal oxides of Cu, Zn, Ni, Fe, and Cr; the stabilizing metal is one or a mixture of at least two of the metal oxides of Ba, Ca, Mg, Cd, and Pb; preferably, the hydrogenation metal oxide is a mixture of Cu and Cr metal oxides; preferably, the molar ratio of Cu and Cr metal oxides is 2-5:5-10; more preferably 4:5.

[0016] The amount of substance of the hydrogenation metal oxide and the stabilizing metal oxide is 5.5-19:1; more preferably 5.5-15:1; most preferably 9:1.

[0017] The present invention also includes a preparation method of the catalyst, which is obtained by mixing the salt solutions of the hydrogenation metal and the stabilizing metal in proportion, stirring, precipitating, pickling, washing with water, drying and then calcining, and ball milling.

[0018] The calcination temperature is 300°C - 350°C.

[0019] The ball milling time is 5-40h, the ball milling speed is 200-600r / min, and the ball-to-material ratio is 2-10:1.

[0020] The present invention also includes an application of the catalyst in the preparation of heptafluoroisobutanol.

[0021] The present invention also includes such an application, which adopts the following steps: introducing the vaporized perfluorocarboxylic acid ester compound and hydrogen into a reactor filled with the catalyst for reaction, and collecting the heptafluoroisobutanol compound through a condensation device after the reaction ends.

[0022] The perfluorocarboxylic acid ester compound is one or a mixture of methyl perfluoroisobutyrate, ethyl perfluoroisobutyrate, or octyl perfluoroisobutyrate.

[0023] The reaction temperature is 180°C - 250°C, preferably 190°C - 200°C; the molar ratio of hydrogen to the perfluorocarboxylic acid ester compound is 5-15:1, preferably 10-15:1.

[0024] The condensation device is a multi-stage condensation device, including a 0°C condensation device connected in sequence to collect low-boiling by-products and a -60°C condensation device for recovering raw materials and collecting the product heptafluoroisobutanol. Compared with the prior art, the beneficial effects of the present invention are:

[0025] The present invention provides a method for preparing heptafluoroisobutanol, specifically a green method for preparing heptafluoroisobutanol by gas-phase catalytic hydrogenation. This method has a short process flow, strong equipment versatility, stable and reliable operation control, and less three-waste emissions, avoiding the problems existing in traditional electrolytic fluorination method, telomerization method, esterification hydrolysis method, and carbonyl compound reduction method. Using the catalyst prepared by the present invention can effectively improve the conversion rate and selectivity. By optimizing the conditions, the product has high purity and yield. This enables the product to be produced on a large scale, and it is inexpensive and easy to promote. Detailed implementation manners

[0026] In order to enable those skilled in the art of the present technology to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the embodiments.

[0027] Example 1

[0028] Preparation of catalyst Cu2Cr9Ca2O 17.5 Weigh 4.83 g (0.02 mol) of copper nitrate trihydrate, 36.01 g (0.09 mol) of chromium nitrate nonahydrate, and 2.22 g (0.02 mol) of calcium chloride and dissolve them in 500 mL of deionized water. Stir to dissolve into a homogeneous solution as solution A. Prepare solution B: Weigh 17.43 g of KF and 40 g of solid KOH and dissolve them in 250 mL of deionized water, stir evenly, and then slowly drop solution B into solution A. After precipitation for 30 min, filter by suction, wash four times with deionized water, and then place it in a forced-air constant-temperature drying oven for drying. Place the catalyst in a tubular furnace for activation. Charge hydrogen under nitrogen protection, and raise the temperature to 350 °C at a rate of 5 °C / min for activation for 2 h (the calcination temperature can be adjusted to 300 °C or 320 °C as needed). Place the sample in a mechanical ball mill, set the ball milling time to 5 h, the ball milling speed to 400 r / min, and the ball-to-material ratio to 7:1 (the ball milling speed can be adjusted to 200 r / min or 600 r / min, and the ball-to-material ratio can be adjusted to 2:1 or 10:1). After ball milling, screen out the 40-80 mesh sample and label it as catalyst Cu2Cr9Ca2O 17.5 .

[0029] In the present invention, the M1 a M2 b M3 c O d is a common representation method for the components of metal oxides in the art. M1, M2, and M3 respectively represent different metals, and a to d represent the relative amounts of substances of each element, satisfying that the total valence of each basic metal oxide is zero.

[0030] Table 1 shows the catalysts obtained corresponding to different hydrogenation metal oxides, stable metal oxides, and different addition amounts.

[0031] Table 1

[0032]

[0033]

[0034] Example 2

[0035] The catalyst obtained in Example 1 is used to prepare heptafluoroisobutanol, specifically comprising the following steps: loading the catalyst into a fixed bed reactor, i.e., a hydrogenation chamber, gasifying methyl perfluoroisobutyrate (or ethyl perfluoroisobutyrate or octyl perfluoroisobutyrate) at 110°C, introducing the gasified methyl perfluoroisobutyrate and hydrogen into the hydrogenation chamber filled with the catalyst, the reduction temperature of the hydrogen chamber is 190°C, the reduction time is 3 hours, and the molar ratio of hydrogen to methyl perfluoroisobutyrate is 10:1; after the reaction is completed, entering a condensation device for product separation. The condensation device is a multiple condensation device, including a 0°C condensation device connected in sequence to collect low-boiling point byproducts, and a -60°C condensation device to recover raw materials and collect the product heptafluoroisobutanol. .

[0036] Table 2 shows the conversion and selectivity obtained by different catalysts. It can be seen from Table 2 that the main active component is the hydrogenation metal oxide, and the composite effect of two hydrogenation metal oxides is better, among which CuO and Cr2O3 composite metal oxides are preferred. The single stable metal oxide has no catalytic activity and only acts as a catalytic stabilizer in the catalytic process to prevent electrons from transferring to the hydrogenation metal, thereby improving the catalytic stability of the catalyst.

[0037] Table 2

[0038]

[0039]

[0040] Example 3

[0041] The catalyst Cu4Cr5BaO 12.5 For the preparation of heptafluoroisobutanol, the reaction parameters are shown in Table 3;

[0042] Table 3 shows the effect of temperature on conversion and selectivity.

[0043] Table 3

[0044] Temperature Conversion rate Selectivity 180 91.2 94.8 190 95.2 96.8 200 94.3 93.2 250 84.9 77.5

[0045] Catalytic hydrogenation is an exothermic reaction, and increasing the temperature is not beneficial to it. In addition, too high a temperature may cause carbon deposition on the catalyst and reduce the service life of the catalyst.

[0046] Table 4 shows the effect of hydrogen ester ratio on conversion and selectivity;

[0047] Table 4

[0048] Hydrogen-ester ratio Conversion rate Selectivity 5:1 85.2 95.1 8：1 90.2 92.7 10:1 95.2 96.8 15:1 94.3 94.2

[0049] Theoretically, the molar ratio of hydrogen to methyl heptafluoroisobutyrate in this reaction is 2:1. Generally, for catalytic hydrogenation reactions, hydrogen needs to be in excess. On the one hand, this is to ensure the complete conversion of raw materials and improve the raw material conversion rate. On the other hand, the reducing effect of hydrogen can eliminate harmful substances, avoid catalyst poisoning, and is conducive to extending the service life of the catalyst.

[0050] In summary, it can be seen that the present invention provides a method for preparing heptafluoroisobutanol, specifically a green method for preparing heptafluoroisobutanol by gas-phase catalytic hydrogenation. This method has a short process flow, strong equipment versatility, stable and reliable operation control, and less three-waste emissions. It avoids the problems existing in traditional methods such as electrolytic fluorination, telomerization, esterification hydrolysis, and reduction of carbonyl compounds. Using the catalyst prepared by the present invention can effectively improve the conversion rate and selectivity. By optimizing conditions, the product has high purity and yield. This enables the product to be produced on a large scale, and it is inexpensive and easy to promote.

[0051] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can still be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. Use of a catalyst in the preparation of heptafluoroisobutanol, characterized in that, The described catalyst includes a hydrogenation metal oxide and a stabilizing metal oxide; the molar ratio of the hydrogenation metal oxide to the stabilizing metal oxide is (5.5 - 19):1; The hydrogenation metal oxide is a mixture of at least two of the oxides of Cu, Zn, Ni, Fe, and Cr; The stabilizing metal is one or a mixture of at least two of the oxides of Ba, Ca, Mg, and Cd; The preparation method of the catalyst is to mix the salt solutions of the hydrogenation metal and the stabilizing metal in proportion, stir, precipitate, wash with water, dry, and then calcine and ball-mill; the calcination is carried out in a tubular furnace, hydrogen is introduced under nitrogen protection, and the temperature is 300°C - 350°C; the ball-milling time is 5 - 40 h, the ball-milling speed is 200 - 600 r / min, and the ball-to-material ratio is 2 - 10:

1.

2. Use of the catalyst according to claim 1 in the preparation of heptafluoroisobutanol, characterized in that, The hydrogenation metal oxide is a mixture of Cu and Cr metal oxides; the molar ratio of Cu and Cr metal oxides is (2 - 5):(5 - 10).

3. Use of the catalyst according to claim 2 in the preparation of heptafluoroisobutanol, characterized in that, The molar ratio of Cu and Cr metal oxides is 4:

5.

4. Use of the catalyst according to claim 1 in the preparation of heptafluoroisobutanol, characterized in that, The molar ratio of the hydrogenation metal oxide to the stabilizing metal oxide is (5.5 - 15):

1.

5. Use of the catalyst according to claim 1 in the preparation of heptafluoroisobutanol, characterized in that, The molar ratio of the hydrogenation metal oxide to the stabilizing metal oxide is 9:

1.

6. Use of the catalyst according to claim 1 in the preparation of heptafluoroisobutanol, characterized in that, The following steps are adopted: The vaporized perfluorocarboxylic acid ester compound and hydrogen are introduced into a reactor containing the catalyst for reaction, and after the reaction is completed, the heptafluoroisobutanol compound is collected through a condensation device.

7. Use of the catalyst according to claim 6 in the preparation of heptafluoroisobutanol, characterized in that, The perfluorocarboxylic acid ester compound is one or a mixture of methyl perfluoroisobutyrate, ethyl perfluoroisobutyrate, or octyl perfluoroisobutyrate.

8. Use of the catalyst according to claim 6 in the preparation of heptafluoroisobutanol, characterized in that, The reaction temperature is 180°C - 250°C; the molar ratio of hydrogen to the perfluorocarboxylic acid ester compound is 5 - 15:

1.

9. Use of the catalyst according to claim 8 in the preparation of heptafluoroisobutanol, characterized in that, The reaction temperature is 190°C - 200°C; the molar ratio of hydrogen to the perfluorocarboxylic acid ester compound is 10 - 15:

1.

10. Use of the catalyst according to claim 6 in the preparation of heptafluoroisobutanol, characterized in that, The condensation device is a multi-stage condensation device, including a 0°C condensation device connected in sequence to collect low-boiling by-products, and a -60°C condensation device for recovering raw materials and collecting the product heptafluoroisobutanol.

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