A catalyst for dehydration nitrilation of heptafluoroisobutyramide and preparation method thereof

Abstract

The present specification discloses a catalyst for dehydration nitrilation of heptafluoroisobutyramide and a preparation method thereof, and relates to the technical field of catalyst preparation for perfluoroisobutyronitrile. The catalyst comprises a foam metal carrier and an active substance, wherein the active substance is uniformly distributed on the surface of the foam metal carrier by electroplating; the preparation method comprises placing the foam metal carrier in acetone, 0.01M hydrochloric acid, deionized water and ethanol solution in sequence for ultrasonication for 5 minutes, and then placing the cleaned foam metal carrier in an electroplating solution for electrodeposition; calcining the metal-plated foam metal carrier in an air atmosphere to obtain a metal oxide-plated foam metal carrier; placing the metal oxide-plated foam metal carrier in ionized water for ultrasonic oscillation and then placing it in a vacuum drying oven for drying to obtain a catalyst, so as to solve the problems of high solvent toxicity, difficult separation, carbon deposition and deactivation, easy pulverization and poor uniformity in the catalytic process for preparing perfluoroisobutyronitrile by dehydration of heptafluoroisobutyramide.

Description

Technical Field

[0001] The invention belongs to the technical field of catalyst preparation for perfluoroisobutyronitrile, and particularly relates to a catalyst for dehydration nitrilation of heptafluoroisobutyramide and a preparation method thereof. Background Art

[0002] As a new type of environmentally friendly insulating arc-extinguishing gas, perfluoroisobutyronitrile has a global warming potential (GWP) of only 2210, which is much lower than sulfur hexafluoride (GWP = 23500). It can be used to replace traditional sulfur hexafluoride insulating gas, greatly reducing the problems caused by the greenhouse effect. Perfluoroisobutyronitrile has attracted the attention of the global electrical industry and has begun to be used. It can be mixed with one or more of CO2, N2, and O2 in the air, and filled into the sealed housing of medium-voltage or high-voltage equipment and used in electrical components of solid dielectric layers. Perfluoroisobutyronitrile is used in medium- and high-voltage power equipment and has the following characteristics: environmentally friendly, excellent insulation performance, excellent arc-extinguishing performance, good compatibility with materials in switches, low toxicity, no flash point, in line with health and safety requirements, and can adapt to harsh low-temperature environments.

[0003] At present, among the many reported synthetic routes of perfluoroisobutyronitrile, the most common one is to use heptafluoroisobutyramide as raw material, and generate perfluoroisobutyronitrile through dehydration reaction at high temperature. The dehydration reaction can be divided into anhydride dehydration method and catalytic dehydration method. The anhydride dehydration method is to carry out dehydration reaction in an organic solvent through inorganic anhydride and organic anhydride. This method has the disadvantages of high three waste discharge and high operation risk (Chinese patents CN108395382A, CN108424375A, CN110642750A, CN108395382A). Therefore, the catalytic dehydration method has gradually become a research hotspot.

[0004] Patent CN118056811A reports a method for preparing fluorine-containing nitrile compounds by dehydrating amide compounds: the amide compounds and acetonitrile form a mixed solution, and under the action of a metal oxide catalyst, a dehydration reaction is performed to obtain a gas phase product of heptafluoroisobutyronitrile and a mixture of acetamide and the catalyst. However, the use of acetonitrile, a toxic and flammable solvent, increases the process risk, increases the amount of three wastes discharged, and makes it difficult to separate the catalyst.

[0005] Patent CN114105820A reports that the raw material heptafluoroisobutyramide undergoes a dehydration reaction under the action of a molecular sieve catalyst to obtain perfluoroisobutyronitrile. Although the process of this method is simple, the molecular sieve has strong acidity, which makes the catalyst easy to be deactivated by carbon deposition. At the same time, the analytical sieve easily absorbs water in the reaction product, making regeneration difficult.

[0006] Patent CN118056809A reports a method for preparing perfluoroisobutyronitrile by gas phase catalysis. Under the action of the oxide of the ferrophilic element, heptafluoroisobutyramide removes one molecule of water to obtain perfluoroisobutyronitrile, but the catalyst is easily pulverized and difficult to recycle.

[0007] Patent CN114057605A reports a method of preparing a catalyst using silicon dioxide, molecular sieve, activated carbon, diatomaceous earth, and montmorillonite as carriers, loading chloride as an active component, and catalyzing the dehydration of amides to prepare corresponding nitrile compounds at 200-400°C. The catalyst preparation process of this route is prone to uneven loading and catalyst pulverization.

[0008] The above-mentioned catalytic process for preparing perfluoroisobutyronitrile by dehydrating heptafluoroisobutyramide has problems such as high solvent toxicity, difficulty in separation, deactivation due to carbon deposition, easy pulverization and poor uniformity. Summary of the invention

[0009] The purpose of the present invention is to provide a catalyst for dehydration nitrilation of heptafluoroisobutyramide and a preparation method thereof, so as to solve the problems of high solvent toxicity, difficult separation, carbon deposition and deactivation, easy pulverization and poor uniformity in the catalytic process for dehydration of heptafluoroisobutyramide to prepare perfluoroisobutyronitrile.

[0010] To achieve the above object, the present invention adopts the following technical solution:

[0011] On the one hand, the present specification provides a catalyst for dehydration nitrilation of heptafluoroisobutyramide, comprising:

[0012] The catalyst comprises a foam metal carrier and an active substance, and the active substance is evenly distributed on the surface of the foam metal carrier by electroplating.

[0013] On the other hand, the present specification provides a method for preparing a catalyst for dehydration nitrilation of heptafluoroisobutyramide, comprising:

[0014] Step 102, placing the foam metal carrier in acetone, 0.01M hydrochloric acid, deionized water and ethanol solution in sequence and performing ultrasonic treatment for 5 minutes to obtain a cleaned foam metal carrier;

[0015] Step 104, placing the cleaned foam metal carrier into an electroplating solution for electrodeposition to obtain a foam metal carrier with a metal coating; the electroplating solution contains the active substance;

[0016] Step 106, calcining the metal-plated foamed metal carrier in an air atmosphere to obtain a metal-oxide-plated foamed metal carrier;

[0017] Step 108, placing the foamed metal carrier with the metal oxide coating in ionized water for ultrasonic vibration and then placing it in a vacuum drying oven for drying to obtain a catalyst.

[0018] In another aspect, the present specification provides a method for dehydrating heptafluoroisobutyramide using a catalyst, comprising:

[0019] Step S1, placing a catalyst into a reactor and heating the reactor to a preset reaction temperature;

[0020] Step S2, using a heatable metering pump to introduce heptafluoroisobutyramide, controlling the heptafluoroisobutyramide feed rate to be a preset feed rate, and the nitrogen purge rate to be a preset nitrogen flow rate, and after reacting for 24 hours, obtaining a dehydration reaction product;

[0021] Step S3, the dehydration reaction product is cooled and separated to obtain an organic phase, and the organic phase is weighed and analyzed by GC to obtain the conversion rate of heptafluoroisobutyramide and the selectivity of perfluoroisobutyronitrile.

[0022] Based on the above technical solution, this specification can achieve the following technical effects:

[0023] The dehydration catalyst prepared by the method is composed of a foam metal carrier and an active substance. The rigidity and plasticity of the foam metal carrier are used to solve the difficult problems of catalyst pulverization, regeneration and recovery. The active substance is evenly distributed on the carrier surface by electroplating. The method has the advantages of simple preparation method and uniform structure; easy separation, regeneration and recovery; and industrial application prospects, thereby solving the problems of high solvent toxicity, difficult separation, carbon deposition and deactivation, easy pulverization and poor uniformity in the catalytic process of preparing perfluoroisobutyronitrile by dehydration of heptafluoroisobutyramide. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The figure is a schematic flow chart of a method for preparing a catalyst for dehydration nitrilation of heptafluoroisobutyramide in one embodiment of the present invention.

[0025] Figure 2 The figure is a schematic flow chart of a method for carrying out a dehydration reaction of heptafluoroisobutyramide using a catalyst in one embodiment of the present invention.

[0026] Figure 3 Schematic diagram of conversion rate and selectivity data of different catalysts in one embodiment of the present invention. DETAILED DESCRIPTION

[0027] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. The advantages and features of the present invention will become more apparent from the following description and claims. It should be noted that the drawings are all in very simplified form and are not in precise proportions, and are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention.

[0028] It should be noted that, in order to clearly explain the content of the present invention, the present invention specifically cites multiple embodiments to further illustrate different implementations of the present invention, wherein the multiple embodiments are enumerated rather than exhaustive. In addition, for the sake of brevity of explanation, the contents mentioned in the previous embodiments are often omitted in the subsequent embodiments. Therefore, the contents not mentioned in the subsequent embodiments can refer to the previous embodiments accordingly.

[0029] This specification provides a catalyst for the dehydration nitrilation of heptafluoroisobutyramide.

[0030] The catalyst comprises a foam metal carrier and active substances, wherein the active substances are evenly distributed on the surface of the foam metal carrier through electroplating.

[0031] Optionally, the foam metal carrier is foam nickel with a content of 60% to 95%.

[0032] Optionally, the active material comprises one or more of zinc oxide, iron oxide, zirconium oxide, manganese oxide and indium oxide, with a mass percentage of 5% to 40%.

[0033] In addition, refer to Figure 1 , this specification provides a method for preparing a catalyst for dehydration nitrilation of heptafluoroisobutyramide, comprising:

[0034] Step 102, placing the foam metal carrier in acetone, 0.01M hydrochloric acid, deionized water and ethanol solution in sequence and performing ultrasonic treatment for 5 minutes to obtain a cleaned foam metal carrier;

[0035] Optionally, the foam metal carrier is a foam nickel column with a diameter of 20 mm and a length of 100 mm.

[0036] Step 104, placing the cleaned foam metal carrier into an electroplating solution for electrodeposition to obtain a foam metal carrier with a metal coating; the electroplating solution contains the active substance;

[0037] Optionally, an implementation of step 104 is:

[0038] Step 202, using the cleaned foam metal carrier as a working electrode, a graphite electrode as a counter electrode, and a saturated calomel electrode as a reference electrode; the graphite electrode has a diameter of 30 mm and a length of 150 mm;

[0039] Step 204, adjusting the pH of the electroplating solution with an ammonia solution having a mass fraction of 5% to obtain an adjusted electroplating solution;

[0040] Step 206 , placing the cleaned foamed metal carrier into the adjusted electroplating solution for electroplating at a preset electroplating solution temperature and a preset current density to obtain a foamed metal carrier with a metal coating.

[0041] Optionally, the components of the electroplating solution are one or more of zinc chloride, ferric chloride, zirconium nitrate, manganese chloride, nickel nitrate and indium chloride.

[0042] Optionally, the concentration of the electroplating solution is 20-100 g / L; the pH of the electroplating solution is 8-11; the preset electroplating solution temperature is 30-60°C; the preset current density is 40-100 mA / cm 2 ; The electroplating time is 10 to 30 minutes.

[0043] Step 106, calcining the metal-plated foamed metal carrier in an air atmosphere to obtain a metal-oxide-plated foamed metal carrier;

[0044] Specifically, the nickel foam obtained in step 104 is calcined in an air atmosphere at 300° C. for a certain period of time.

[0045] Optionally, the calcination time is 10 to 30 minutes.

[0046] Step 108, placing the foamed metal carrier with the metal oxide coating in ionized water for ultrasonic vibration and then placing it in a vacuum drying oven for drying to obtain a catalyst.

[0047] In addition, refer to Figure 2 This embodiment provides a method for carrying out a dehydration reaction of heptafluoroisobutyramide using the catalyst, comprising:

[0048] Step S1, placing a catalyst into a reactor and heating the reactor to a preset reaction temperature;

[0049] Step S2, using a heatable metering pump to introduce heptafluoroisobutyramide, controlling the feeding rate of heptafluoroisobutyramide to be a preset feeding rate, and the nitrogen purge rate to be a preset nitrogen flow rate, and after reacting for 24 hours, obtaining a dehydration reaction product;

[0050] Step S3, the dehydration reaction product is cooled and separated to obtain an organic phase, and the organic phase is weighed and analyzed by GC to obtain the conversion rate of heptafluoroisobutyramide and the selectivity of perfluoroisobutyronitrile.

[0051] Optionally, the preset reaction temperature is 300-500° C.; the preset nitrogen flow rate is 20-100 mL / min, and the reaction pressure is normal pressure.

[0052] Preferably, the catalyst is a supported catalyst.

[0053] Based on this, this embodiment has the following beneficial effects:

[0054] (1) The catalyst preparation route is novel, using nickel foam columns as carriers. The catalyst has strong designability, can be customized according to the reactor size, and has high structural strength.

[0055] (2) The active material is loaded by electrodeposition. The coating is dense and uniform, the coating thickness is adjustable, there are many active sites of metal oxides on the surface, and the catalyst has high catalytic efficiency.

[0056] (3) The selected supported catalyst has high selectivity for the main product perfluoroisobutyronitrile, which greatly improves the yield of the catalytic dehydration reaction.

[0057] In summary, the dehydration catalyst prepared by the method is composed of a foam metal carrier and an active substance. The rigidity and plasticity of the foam metal carrier are used to solve the problems of catalyst pulverization, regeneration and recovery difficulties. The active substance is evenly distributed on the carrier surface by electroplating, and has the advantages of simple preparation method and uniform structure; easy separation, regeneration and recovery; and industrial application prospects, thereby solving the problems of high solvent toxicity, difficult separation, carbon deposition and deactivation, easy pulverization and poor uniformity in the catalytic process of dehydrating heptafluoroisobutyramide to prepare perfluoroisobutyronitrile. Example 1

[0058] (1) Preparation method of ZnO / nickel foam catalyst:

[0059] Prepare ZnCl with a mass concentration of 20g / L 2 Plating solution: put the cleaned nickel foam column into the plating solution, adjust the pH value of the plating solution to 8 with a 5% ammonia solution, set the plating solution temperature to 30°C, and the current density to 40mA / cm 2 , the electroplating time is 10 minutes, and nickel foam plated with metallic zinc is obtained.

[0060] The nickel foam obtained in step (1) was calcined at 300°C in air atmosphere for 10 min. The metal zinc coating was changed into a zinc oxide coating. The entire nickel foam column was placed in deionized water for ultrasonic oscillation to remove excess zinc oxide powder on the surface, and then placed in a vacuum drying oven for drying. The loading was calculated to be 5% by weighing.

[0061] (2) Catalytic dehydration reaction

[0062] A ZnO / nickel foam column was placed in a reactor, the reactor was heated to 400°C, heptafluoroisobutyramide was introduced using a heatable metering pump, the heptafluoroisobutyramide feed rate was controlled to be 0.1 g / min, and the nitrogen purge rate was 20 mL / min. After reacting for 24 hours, the reaction product was cooled and separated to obtain an organic phase, the organic phase was weighed and analyzed by GC to obtain conversion rate and selectivity data: the conversion rate of heptafluoroisobutyramide was 85.2%, and the selectivity of perfluoroisobutyronitrile was 78.3%. Example 2

[0063] The supported catalyst was prepared by referring to Example 1. 2The concentration of the plating solution was changed to 40 g / L, and other experimental conditions remained unchanged. The loading was calculated to be 7%. The catalyst was placed in a reactor for catalytic dehydration, and the conversion rate and selectivity data were obtained: the conversion rate of heptafluoroisobutyramide was 95.2%, and the selectivity of perfluoroisobutyronitrile was 82.5%. Example 3

[0064] The supported catalyst was prepared by referring to Example 1. 2 The concentration of the plating solution was changed to 60 g / L, and other experimental conditions remained unchanged. The loading was calculated to be 10%. The catalyst was placed in a reactor for catalytic dehydration, and the conversion rate and selectivity data were obtained: the conversion rate of heptafluoroisobutyramide was 92.5%, and the selectivity of perfluoroisobutyronitrile was 81.8%. Example 4

[0065] The supported catalyst was prepared by referring to Example 1. 2 The concentration of the plating solution was changed to 100 g / L, and other experimental conditions remained unchanged. The loading was calculated to be 15%. The catalyst was placed in a reactor for catalytic dehydration, and the conversion rate and selectivity data were obtained: the conversion rate of heptafluoroisobutyramide was 90.4%, and the selectivity of perfluoroisobutyronitrile was 82.8%. Example 5

[0066] The supported catalyst was prepared by referring to Example 1. 2 The concentration of the electroplating solution was changed to molybdenum nitrate solution, and other experimental conditions remained unchanged. The loading was calculated to be 14.5%. The catalyst was placed in a reactor for catalytic dehydration, and the conversion rate and selectivity data were obtained: the conversion rate of heptafluoroisobutyramide was 94.5%, and the selectivity of perfluoroisobutyronitrile was 86.8%. Example 6

[0067] (1) Fe 2 O 3 / Preparation of foam nickel catalyst:

[0068] Prepare FeCl with a mass concentration of 40 g / L 3 Plating solution: put the cleaned nickel foam column into the plating solution, adjust the pH value of the plating solution to 8 with a 5% ammonia solution, set the plating solution temperature to 30°C, and the current density to 40mA / cm 2 , the electroplating time is 10 minutes, and foam nickel plated with metallic iron is obtained.

[0069] The nickel foam obtained in step (1) was calcined at 300°C in air atmosphere for 10 min. The metal iron coating was changed into an iron oxide coating. The entire nickel foam column was placed in deionized water for ultrasonic oscillation to remove excess iron oxide powder on the surface, and then placed in a vacuum drying oven for drying. The loading was calculated by weighing to be 9%.

[0070] (2) Catalytic dehydration reaction

[0071] Fe 2 O 3 / The nickel foam column is placed in the reactor, the reactor is heated to 400°C, heptafluoroisobutyramide is introduced using a heatable metering pump, the heptafluoroisobutyramide feed rate is controlled to be 0.1 g / min, the nitrogen purge rate is controlled to be 20 mL / min, after reacting for 24 hours, the reaction product is cooled and separated to obtain an organic phase, the organic phase is weighed and analyzed by GC to obtain conversion rate and selectivity data: the conversion rate of heptafluoroisobutyramide is 86.7%, and the selectivity of perfluoroisobutyronitrile is 85.2%. Example 7

[0072] The supported catalyst was prepared with reference to Example 6, and the pH in Example 6 was adjusted to 9, and other experimental conditions remained unchanged. The loading amount was calculated to be 11%, and the catalyst was placed in a reactor for catalytic dehydration to obtain conversion rate and selectivity data: the conversion rate of heptafluoroisobutyramide was 95.7%, and the selectivity of perfluoroisobutyronitrile was 92.8%. Example 8

[0073] The supported catalyst was prepared with reference to Example 6, the pH in Example 6 was adjusted to 10, and other experimental conditions remained unchanged. The loading amount was calculated to be 8%, and the catalyst was placed in a reactor for catalytic dehydration to obtain conversion rate and selectivity data: the conversion rate of heptafluoroisobutyramide was 90.3%, and the selectivity of perfluoroisobutyronitrile was 88.2%. Example 9

[0074] The supported catalyst was prepared with reference to Example 6, the pH value in Example 6 was adjusted to 11, and other experimental conditions remained unchanged. The loading amount was calculated to be 6%, and the catalyst was placed in a reactor for catalytic dehydration to obtain conversion rate and selectivity data: the conversion rate of heptafluoroisobutyramide was 86.7%, and the selectivity of perfluoroisobutyronitrile was 85.8%. Example 10

[0075] (1) MnO 2 / Preparation of foam nickel catalyst:

[0076] Prepare a manganese chloride electroplating solution with a mass concentration of 40g / L, put the cleaned nickel foam column into the electroplating solution, adjust the pH of the electroplating solution to 9 with a 5% ammonia solution, set the electroplating solution temperature to 30℃, and the current density to 40mA / cm 2 , the electroplating time is 10 min. A nickel foam plated with metallic iron is obtained. The nickel foam obtained in step (1) is calcined in an air atmosphere at 300°C for 10 min. The metallic manganese coating is changed into a manganese oxide coating. The entire nickel foam column is ultrasonically vibrated in deionized water to remove excess iron oxide powder on the surface, and then placed in a vacuum drying oven for drying. The loading amount is calculated by weighing to be 6%.

[0077] (2) Catalytic dehydration reaction

[0078] MnO 2 / The nickel foam column is placed in the reactor, the reactor is heated to 400°C, heptafluoroisobutyramide is introduced using a heatable metering pump, the heptafluoroisobutyramide feed rate is controlled to be 0.1 g / min, the nitrogen purge rate is controlled to be 20 mL / min, after reacting for 24 hours, the reaction product is cooled and separated to obtain an organic phase, the organic phase is weighed and analyzed by GC to obtain conversion rate and selectivity data: the conversion rate of heptafluoroisobutyramide is 92.7%, and the selectivity of perfluoroisobutyronitrile is 84.2%. Embodiment 11

[0079] The supported catalyst was prepared by referring to Example 10, and the temperature of the electroplating solution in Example 10 was adjusted to 40° C., and other experimental conditions remained unchanged. The loading amount was calculated to be 8%, and the catalyst was placed in a reactor for catalytic dehydration to obtain conversion rate and selectivity data: the conversion rate of heptafluoroisobutyramide was 95.7%, and the selectivity of perfluoroisobutyronitrile was 90.8%. Example 12

[0080] The supported catalyst was prepared by referring to Example 10, and the temperature of the electroplating solution in Example 10 was adjusted to 60° C., and other experimental conditions remained unchanged. The loading amount was calculated to be 5%, and the catalyst was placed in a reactor for catalytic dehydration to obtain conversion rate and selectivity data: the conversion rate of heptafluoroisobutyramide was 88.4%, and the selectivity of perfluoroisobutyronitrile was 89.8%. Embodiment 13

[0081] (1) In 2 O 3 / Preparation of foam nickel catalyst:

[0082] Prepare an indium nitrate electroplating solution with a mass concentration of 40g / L, put the cleaned nickel foam column into the electroplating solution, adjust the pH of the electroplating solution to 9 with a 5% ammonia solution, set the electroplating solution temperature to 40℃, and the current density to 40mA / cm 2, the electroplating time is 10 min. A nickel foam plated with metal indium is obtained. The nickel foam obtained in step (1) is calcined in an air atmosphere at 300°C for 10 min. The metal indium coating is changed into an indium oxide coating. The entire nickel foam column is placed in deionized water for ultrasonic oscillation to remove excess indium oxide powder on the surface, and then placed in a vacuum drying oven for drying. The loading amount is calculated by weighing to be 12%.

[0083] (2) Catalytic dehydration reaction

[0084] In 2 O 3 / The nickel foam column is placed in the reactor, the reactor is heated to 400°C, heptafluoroisobutyramide is introduced using a heatable metering pump, the heptafluoroisobutyramide feed rate is controlled to be 0.1 g / min, the nitrogen purge rate is controlled to be 20 mL / min, after reacting for 24 hours, the reaction product is cooled and separated to obtain an organic phase, the organic phase is weighed and analyzed by GC to obtain conversion rate and selectivity data: the conversion rate of heptafluoroisobutyramide is 93.5%, and the selectivity of perfluoroisobutyronitrile is 89.2%. Embodiment 14

[0085] The supported catalyst was prepared by referring to Example 13, and the current density in Example 13 was adjusted to 50 mA / cm 2 , other experimental conditions remain unchanged. The loading amount is calculated to be 13%, and the catalyst is placed in a reactor for catalytic dehydration to obtain conversion rate and selectivity data: the conversion rate of heptafluoroisobutyramide is 94.4%, and the selectivity of perfluoroisobutyronitrile is 95.4%. Embodiment 15

[0086] The supported catalyst was prepared by referring to Example 13, and the current density in Example 13 was adjusted to 60 mA / cm 2 , other experimental conditions remain unchanged. The loading amount is calculated to be 15%, and the catalyst is placed in a reactor for catalytic dehydration to obtain conversion rate and selectivity data: the conversion rate of heptafluoroisobutyramide is 91.5%, and the selectivity of perfluoroisobutyronitrile is 94.4%. Example 16

[0087] The supported catalyst was prepared by referring to Example 13, and the current density in Example 13 was adjusted to 100 mA / cm 2 , other experimental conditions remain unchanged. The loading amount is calculated to be 20%, and the catalyst is placed in a reactor for catalytic dehydration to obtain conversion rate and selectivity data: the conversion rate of heptafluoroisobutyramide is 90.5%, and the selectivity of perfluoroisobutyronitrile is 93.6%. Embodiment 17

[0088] The supported catalyst was prepared by referring to Example 1, except that the electroplating time in Example 1 was changed to 20 min, and other experimental conditions remained unchanged. The loading amount was calculated to be 10%. The catalyst was placed in a reactor for catalytic dehydration, and the conversion rate and selectivity data were obtained: the conversion rate of heptafluoroisobutyramide was 93.5%, and the selectivity of perfluoroisobutyronitrile was 81.8%. Embodiment 18

[0089] The supported catalyst was prepared by referring to Example 1, except that the electroplating time in Example 1 was changed to 30 min, and other experimental conditions remained unchanged. The loading amount was calculated to be 18%. The catalyst was placed in a reactor for catalytic dehydration, and the conversion rate and selectivity data were obtained: the conversion rate of heptafluoroisobutyramide was 91.5%, and the selectivity of perfluoroisobutyronitrile was 80.8%. Embodiment 19

[0090] The supported catalyst was prepared by referring to Example 6, except that the calcination time in Example 6 was changed to 20 min, and other experimental conditions remained unchanged. The loading amount was calculated to be 13%, and the catalyst was placed in a reactor for catalytic dehydration to obtain conversion rate and selectivity data: the conversion rate of heptafluoroisobutyramide was 90.7%, and the selectivity of perfluoroisobutyronitrile was 91.8%. Embodiment 20

[0091] The supported catalyst was prepared with reference to Example 6, except that the calcination time in Example 6 was changed to 30 min, and other experimental conditions remained unchanged. The loading amount was calculated to be 16%, and the catalyst was placed in a reactor for catalytic dehydration to obtain conversion rate and selectivity data: the conversion rate of heptafluoroisobutyramide was 88.7%, and the selectivity of perfluoroisobutyronitrile was 90.8%.

[0092] Comparative Example 1

[0093] The supported catalyst was prepared with reference to Example 1, the concentration of the electroplating solution in Example 1 was adjusted to 150 g / L, and other experimental conditions remained unchanged. The loading amount was calculated to be 25%. The collected organic phase was weighed and analyzed by GC to obtain conversion rate and selectivity data: the conversion rate of heptafluoroisobutyramide was 60.2%, and the selectivity of perfluoroisobutyronitrile was 65.5%.

[0094] Comparative Example 2

[0095] The supported catalyst was prepared with reference to Example 1, and the pH of the electroplating solution in Example 1 was adjusted to 12, and other experimental conditions remained unchanged. The loading amount was calculated to be 7%. The collected organic phase was weighed and analyzed by GC to obtain conversion rate and selectivity data: the conversion rate of heptafluoroisobutyramide was 30.2%, and the selectivity of perfluoroisobutyronitrile was 50.6%.

[0096] Comparative Example 3

[0097] The supported catalyst was prepared by referring to Example 1, and the plating solution temperature in Example 1 was set to 80°C, and other experimental conditions remained unchanged. The loading amount was calculated to be 9%. The collected organic phase was weighed and analyzed by GC to obtain the conversion rate and selectivity data: the conversion rate of heptafluoroisobutyramide was 26.4%, and the selectivity of perfluoroisobutyronitrile was 35.7%.

[0098] Comparative Example 4

[0099] The supported catalyst was prepared by referring to Example 1, and the current density in Example 1 was set to 150 mA / cm 2 , other experimental conditions remain unchanged. The loading capacity is calculated to be 27%. The collected organic phase is weighed and analyzed by GC to obtain the conversion rate and selectivity data: the conversion rate of heptafluoroisobutyramide is 67.4%, and the selectivity of perfluoroisobutyronitrile is 70.2%.

[0100] Comparative Example 5

[0101] The supported catalyst was prepared with reference to Example 1, the electroplating time in Example 1 was set to 50 min, and other experimental conditions remained unchanged. The loading amount was calculated to be 22%. The collected organic phase was weighed and analyzed by GC to obtain conversion rate and selectivity data: the conversion rate of heptafluoroisobutyramide was 47.5%, and the selectivity of perfluoroisobutyronitrile was 60.6%.

[0102] Comparative Example 6

[0103] The supported catalyst was prepared by referring to Example 1, and the calcination time in Example 1 was set to 60 min, and other experimental conditions remained unchanged. The loading amount was calculated to be 30%. The collected organic phase was weighed and analyzed by GC to obtain conversion rate and selectivity data: the conversion rate of heptafluoroisobutyramide was 44.5%, and the selectivity of perfluoroisobutyronitrile was 50.6%.

[0104] refer to Figure 3 It can be seen from Examples 1-5 and Comparative Example 1 that the supported catalyst ZnO / nickel foam has an effect on the conversion rate of heptafluoroisobutyramide and the selectivity of perfluoroisobutyronitrile as the concentration of the plating solution increases. When the concentration of the plating solution is 40 g / L, the conversion rate of perfluoroisobutyronitrile reaches 95.2%. The possible reason is that as the concentration of the plating solution increases, the number of ion migrations per unit time increases, and the surface coating of the nickel foam becomes thicker, which is not conducive to the catalytic reaction.

[0105] Preferably, the concentration of the plating solution in this specification is in the range of 40 to 60 g / L.

[0106] refer to Figure 3From Examples 6-10 and Comparative Example 2, it can be seen that the supported catalyst Fe 2 O 3 / / As the pH value of the electroplating solution increases, the amide conversion rate and the selectivity of perfluoroisobutyronitrile in the nickel foam first increase and then decrease. The possible reason is that the increase in the pH value of the electroplating solution increases the OH content in the electroplating solution. -1 It forms metal complexes with metal ions, making the electroplating solution turbid, which is not conducive to the deposition of the metal layer on the nickel foam.

[0107] Preferably, the nitrogen flow rate of the reactor in this specification is controlled at 9-10.

[0108] refer to Figure 3 From Examples 10-12 and Comparative Example 3, it can be seen that the supported catalyst MnO 2 / As the temperature of the electroplating solution increases, the amide conversion rate and the selectivity of perfluoroisobutyronitrile are affected. When the temperature of the electroplating solution is low, the ion mobility is slow, resulting in uneven metal deposition on the nickel foam. When the temperature of the electroplating solution is high, the ion migration rate is fast, and the metal layer on the nickel foam is deposited too quickly, resulting in an overly thick electroplating layer, which is not conducive to the catalytic reaction. When the temperature is too high, the metal complex increases during the electroplating process, resulting in a loose electroplating layer, and the metal oxide powder falls off during the catalytic reaction, affecting the catalytic reaction.

[0109] Preferably, the temperature of the electroplating solution in this specification is 40°C.

[0110] refer to Figure 3 From Examples 13-16 and Comparative Example 4, it can be seen that the supported catalyst In 2 O 3 / As the current density of the electroplating solution increases, the conversion rate of amide and the selectivity of perfluoroisobutyronitrile increase first and then decrease. The possible reason is that the increase in current density leads to faster ion migration rate, resulting in delayed growth of the electroplated layer, and poor growth density and uniformity, which affects the subsequent catalytic reaction.

[0111] Preferably, the current density in this specification is 40~60mA / cm 2 .

[0112] refer to Figure 3 It can be seen from Examples 16-20 and Comparative Examples 5-6 that the supported catalyst has an influence on the amide conversion rate and perfluoroisobutyronitrile selectivity along with the electroplating time and calcination time.

[0113] Preferably, in this specification, the electroplating time is 10-20 min, and the calcination time is 10-20 min.

[0114] The above is only an embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the scope of the claims of the present application.

Claims

1. A method for dehydrating heptafluoroisobutyramide using a catalyst, characterized in that: include: Putting the catalyst into the reactor and heating the reactor to a preset reaction temperature; Using a heatable metering pump to introduce heptafluoroisobutyramide, controlling the heptafluoroisobutyramide feed rate to be a preset feed rate, and the nitrogen purge rate to be a preset nitrogen flow rate, and obtaining a dehydration reaction product after passing through a catalyst bed; The dehydration reaction product is cooled and separated to obtain an organic phase, and the organic phase is weighed and analyzed by GC to obtain the conversion rate of heptafluoroisobutyramide and the selectivity of perfluoroisobutyronitrile; The catalyst comprises a foam metal carrier and an active substance, wherein the active substance is evenly distributed on the surface of the foam metal carrier by electroplating; The foam metal carrier is foam nickel, with a content of 60% to 95%; The components of the active material are one or more of zinc oxide, iron oxide, manganese oxide and indium oxide, with a mass percentage of 5% to 40%.

2. The method according to claim 1, characterized in that The preset reaction temperature is 300-500° C.; the preset nitrogen flow rate is 20-100 mL / min, and the reaction pressure is normal pressure.

3. The method according to claim 1, characterized in that The preparation method of the catalyst comprises: The foamed metal carrier was sequentially placed in acetone, 0.01M hydrochloric acid, deionized water and ethanol solution and subjected to ultrasonic treatment for 5 minutes to obtain a cleaned foamed metal carrier; placing the cleaned foamed metal carrier into an electroplating solution for electrodeposition to obtain a foamed metal carrier with a metal coating; the electroplating solution contains the active substance; calcining the metal-plated foamed metal carrier in an air atmosphere to obtain the metal-oxide-plated foamed metal carrier; The foamed metal carrier with the metal oxide coating is placed in ionized water for ultrasonic oscillation and then placed in a vacuum drying oven for drying to obtain a catalyst.

4. The method according to claim 3, characterized in that: The foam metal carrier is a foam nickel column with a diameter of 20 mm and a length of 100 mm.

5. The method according to claim 3, characterized in that: The step of placing the cleaned foamed metal carrier into an electroplating solution for electroplating to obtain a foamed metal carrier with a metal coating comprises: The cleaned foam metal carrier is used as a working electrode, a graphite electrode is used as a counter electrode, and a saturated calomel electrode is used as a reference electrode; the graphite electrode has a diameter of 30 mm and a length of 150 mm; The pH of the electroplating solution is adjusted using a 5% by mass ammonia solution to obtain an adjusted electroplating solution; At a preset electroplating solution temperature and a preset current density, the cleaned foam metal carrier is placed in an adjusted electroplating solution for electroplating to obtain a foam metal carrier with a metal coating.

6. The method according to claim 5, characterized in that The components of the electroplating solution are one or more of zinc chloride, ferric chloride, manganese chloride and indium chloride.

7. The method according to claim 6, characterized in that The concentration of the electroplating solution is 20-100 g / L; the pH of the electroplating solution is 8-11; the preset electroplating solution temperature is 30-60° C.; the preset current density is 40-100 mA / cm 2 ; The electroplating time is 10 to 30 minutes.

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