Catalyst for preparing 2, 3-dichloropyridine and preparation method thereof

Abstract

The invention discloses a catalyst for preparing 2, 3-dichloropyridine and a preparation method of the catalyst. The preparation method of the catalyst comprises the following steps: dissolving active components of the catalyst in a solvent, uniformly stirring, then adding a template agent, nitric acid and boron nitride, continuously stirring, then adding an aluminum salt, putting into an ultrasonic cleaning instrument, and carrying out ultrasonic treatment at the ultrasonic frequency of 20-40kHz for 60-90 minutes to fully dissolve the aluminum salt; the preparation method comprises the following steps: dissolving the raw materials in a solvent to obtain sol, aging the sol at 40-70 DEG C for 8-16 hours to gelatinize the sol, and drying at 90-150 DEG C for 4-48 hours. Based on the total mass of the catalyst, the mass percentage content of the catalyst active component is 5-20%, the mass percentage content of the alumina carrier is 60-80%, and the mass percentage content of the boron nitride is 5-15%. The specific surface area and the pore volume of the catalyst are improved, the thermal stability and the chemical stability of the catalyst are enhanced, the catalytic efficiency is improved, and the service life is prolonged.

Description

Technical Field

[0001] The present invention relates to the technical field of catalysis, and in particular to a catalyst for preparing 2,3-dichloropyridine and a preparation method thereof, specifically a catalyst for reacting 2-chloropyridine with chlorine to generate 2,3-dichloropyridine and a preparation method thereof. Background Art

[0002] As an important chemical intermediate, 2,3-dichloropyridine has extremely important industrial and application value. It can not only be used as a key raw material for the synthesis of a variety of high-efficiency and low-toxic pesticides, such as for the production of insecticides such as chlorantraniliprole, but also plays an important role in the pharmaceutical field. It can be used as a precursor of important pharmacologically active drugs such as torsemide. In addition, 2,3-dichloropyridine is also widely used in the synthesis of dyes, fragrances and other chemicals. Therefore, the development of a new environmentally friendly synthesis method for 2,3-dichloropyridine is of great practical significance.

[0003] There are two main methods for the synthesis of 2,3-dichloropyridine: one is through the "nicotinamide route" and the other is through the "2,3,6-trichloropyridine catalytic reduction method". However, these traditional methods have many disadvantages. First, the nicotinamide route starts from nicotinamide, undergoes Hofmann amide degradation to generate 3-aminopyridine, and then undergoes multiple steps of reaction to finally prepare 2,3-dichloropyridine through diazotization. Although this route can effectively prepare the target product, the steps are cumbersome and the production cost is high. Secondly, in the process of preparing 2,3-dichloropyridine through catalytic reduction using 2,3,6-trichloropyridine as a raw material, expensive metal catalysts (such as palladium, platinum, Raney nickel or Raney copper) are often used. Such catalysts are easily poisoned and fail, resulting in low conversion rate of 2,3,6-trichloropyridine and poor selectivity of the target product 2,3-dichloropyridine, which affects the industrial application of the process. In addition, some existing technologies such as patented methods (such as US5380862A1 and EP0591624A1) propose to use 2-chloropyridine as a raw material to prepare 2,3-dichloropyridine through multiple steps such as etherification and chlorination, but they also have the problems of complicated steps, low yield and harsh reaction conditions. These shortcomings make it difficult for the existing 2,3-dichloropyridine synthesis process to achieve efficient and economical production in practical applications.

[0004] To solve the above problems, the present invention proposes a novel boron nitride-alumina composite carrier supported catalyst to improve the selectivity of 2-chloropyridine chlorination reaction and the service life of the catalyst, thereby improving the yield of 2,3-dichloropyridine. Summary of the invention

[0005] The object of the present invention is to provide a catalyst for preparing 2,3-dichloropyridine and a preparation method thereof, wherein the catalyst has the advantages of high activity, good stability, long service life and the like.

[0006] To achieve the above object, the present invention provides a catalyst for preparing 2,3-dichloropyridine and a preparation method thereof, comprising the following steps:

[0007] The active components of the catalyst are dissolved in a solvent and stirred evenly, and then a template and nitric acid are added and stirred continuously, and then aluminum salt is added and placed in an ultrasonic cleaner to be fully dissolved by ultrasound, and a sol is obtained after dissolution, and then a boron nitride-alumina composite carrier-supported catalyst is obtained after aging, drying and calcination.

[0008] In the present invention, the catalyst comprises a catalytically active component supported on a composite carrier, and the active component of the catalyst is selected from one or two metal chlorides such as ferric chloride, copper chloride, zinc chloride, cobalt chloride, lanthanum chloride, cerium chloride and the like.

[0009] In the present invention, based on the total mass of the catalyst, the mass percentage of the catalyst active component is 5-20%, preferably 8-15%. The mass percentage of the alumina carrier is 60-80%, preferably 65-75%. The mass percentage of the boron nitride is 5-15%, preferably 8-12%.

[0010] In the present invention, the aluminum salt includes aluminum alcohol salts such as aluminum isopropoxide, aluminum sec-butoxide, and aluminum triethoxide.

[0011] In the present invention, the boron nitride is one of hexagonal boron nitride (HBN), rhombohedral boron nitride (RBN), cubic boron nitride (CBN) and wurtzite boron nitride (WBN).

[0012] In the present invention, the solvent is an alcohol solvent such as anhydrous methanol, anhydrous ethanol or isopropanol, the template is F127 (polyoxyethylene-polyoxypropylene copolymer), P123 (polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer) or CTAB (hexadecyltrimethylammonium bromide), and the mass ratio of the template to the aluminum salt is 1:2-1:20, preferably 1:5-1:15.

[0013] In the present invention, the ultrasonic treatment time is 60-90 minutes, and the ultrasonic frequency is 20-40kHz.

[0014] In the present invention, during the preparation of the catalyst, the sol aging temperature is 40-70°C, preferably 45-65°C, more preferably 50-60°C, and the aging time is 8-16h, preferably 10-15h, more preferably 12-14h to gelate it.

[0015] In the present invention, the drying temperature is 90-150°C, preferably 100-140°C, more preferably 110-130°C, and the drying time is 4-48h, preferably 15-40h, more preferably 20-30h.

[0016] In the present invention, the calcination temperature of the catalyst is 350-500° C., preferably 400-450° C., and the calcination time is 2-8 hours, preferably 4-6 hours.

[0017] In the present invention, the catalyst is calcined in an atmosphere of nitrogen, argon or other inert gases to prevent oxidation of active components.

[0018] The beneficial effects of the present invention are as follows:

[0019] The catalyst of the present invention achieves high specific surface area and pore volume by optimizing the preparation process, enhances the thermal stability and chemical stability of the catalyst, and improves the catalytic efficiency and service life. The catalyst of the present invention has the advantages of high activity, good stability and long service life. DETAILED DESCRIPTION

[0020] The present invention will be further described in detail below through specific examples to facilitate a clearer understanding of the present invention, but they do not constitute a limitation of the present invention.

[0021] The invention discloses a catalyst for preparing 2,3-dichloropyridine and a preparation method thereof. The steps of preparing the catalyst of the invention are as follows: dissolving the active components of the catalyst in a solvent, stirring evenly, then adding a template, nitric acid and boron nitride and continuing to stir, then adding aluminum salt and placing it in an ultrasonic cleaning instrument for ultrasonication to fully dissolve it, the ultrasonic treatment time is 60-90 minutes, and the ultrasonic frequency is 20-40kHz; after dissolving, a sol is obtained, and then the sol is aged at 40-70°C for 8-16h to gelate it, and then dried at 90-150°C for 4-48h. Based on the total mass of the catalyst, the mass percentage of the active components of the catalyst is 5-20%, the mass percentage of the alumina carrier is 60-80%, and the mass percentage of the boron nitride is 5-15%. The invention not only improves the specific surface area and pore volume of the catalyst, but also enhances its thermal stability and chemical stability, and improves the catalytic efficiency and service life.

[0022] Example 1

[0023] Dissolve 1.9g of cupric chloride in 80mL of isopropanol, stir evenly, add 5.6g of F127, 3.5mL of 68% nitric acid and 1.6g of wurtzite boron nitride, and continue stirring for 20 minutes. Then add 24.5g of aluminum sec-butoxide, put it in an ultrasonic cleaner and treat it for 90 minutes at a frequency of 28kHz. Then age the sol at 50°C for 10h to gel it, and dry it at 120°C for 24h. The dried gel is calcined in a nitrogen atmosphere at 450°C for 6h to obtain a catalyst.

[0024] Example 2

[0025] Dissolve 2g of ferric chloride and 1.3g of cobalt chloride in 120mL of anhydrous ethanol, stir evenly, then add 2.2g of F127, 1.5mL of 68% nitric acid and 1.8g of cubic boron nitride, and continue stirring for 15 minutes. Then add 36.1g of aluminum isopropoxide to the solution, put it into an ultrasonic cleaner for ultrasonic treatment for 90 minutes, and the ultrasonic frequency is 25kHz. After the ultrasonic treatment is completed, the sol is aged at 50°C for 10h to gel, and then the gel is placed at 100°C and dried for 24h. Then it is calcined at 400°C in an argon atmosphere for 4h to obtain a supported catalyst.

[0026] Example 3

[0027] Dissolve 1.5g of copper chloride and 1.1g of zinc chloride in 60mL of anhydrous methanol, stir evenly, add 2g of P123, 1.3mL of 68% nitric acid and 1.2g of rhombohedral boron nitride and stir for 15 minutes. Then, add 36.2g of aluminum sec-butoxide to the solution and ultrasonically treat it in an ultrasonic cleaner for 60 minutes at a frequency of 30kHz. After the sol is formed, it is aged at 60°C for 8h to obtain a gel. The gel is then dried at 120°C for 36h and then calcined at 450°C in a nitrogen atmosphere for 6h to obtain a catalyst.

[0028] Example 4

[0029] Dissolve 1.9g of lanthanum chloride and 1.3g of ferric chloride in 60mL of isopropanol, stir evenly, add 1.9g of CTAB and 1.0mL of 68% nitric acid and 1.7g of cubic boron nitride, and continue stirring for 20 minutes. Then, add 38.5g of aluminum isopropoxide and ultrasonically treat for 80 minutes at an ultrasonic frequency of 35kHz. The obtained sol is aged at 55°C for 10h to gel. The gel drying temperature is 110°C, the drying time is 30h, and after drying, it is calcined at 500°C in a helium atmosphere for 5h to obtain a catalyst.

[0030] Example 5

[0031] Dissolve 2.5g of cerium chloride and 1.7g of magnesium chloride in 90mL of anhydrous ethanol and stir evenly. Then add 5.3g of P123, 2.3mL of 68% nitric acid and 2.3g of hexagonal boron nitride and stir for 20 minutes. Add 79.5g of aluminum triethanolate and place in an ultrasonic cleaner for 75 minutes at a frequency of 40kHz. The resulting sol is aged at 45°C for 14h and dried at 130°C for 20h after gelation. The dried gel is calcined in an argon atmosphere at 400°C for 5h to obtain a catalyst.

[0032] Comparative Example 1

[0033] The same amount of isopropanol, F127 and nitric acid as in Example 1 were added to a beaker at once and stirred for 20 minutes. The same amount of aluminum sec-butoxide and wurtzite boron nitride as in Example 1 were added to the solution, and then placed in an ultrasonic cleaner for ultrasonic treatment for 90 minutes at an ultrasonic frequency of 28kHz. After the ultrasonic treatment, the solution was aged at 50°C for 10 hours to gel. The gel was then dried at 120°C for 24 hours. The dried gel was calcined at 450°C in a nitrogen atmosphere for 6 hours to obtain a boron nitride-alumina composite carrier.

[0034] The same amount of copper chloride as in Example 1 was loaded on a boron nitride-alumina composite carrier by an impregnation method and dried at 120° C., and then calcined in a nitrogen atmosphere at 450° C. to obtain a catalyst for use.

[0035] Comparative Examples 2-5

[0036] The method of Comparative Example 1 was adopted to form catalysts by impregnation method according to the component amounts of Examples 2-5 respectively.

[0037] Comparative Example 6

[0038] The same amount of copper chloride and isopropanol as in Example 1 were added into a beaker at once and stirred for 15 minutes, and 10 g of activated carbon was added and placed in an ultrasonic cleaner for ultrasonic treatment for 90 minutes at an ultrasonic frequency of 28 kHz. After the ultrasonic treatment, the mixture was first soaked at room temperature for 12 hours, then the temperature was gradually increased to 120°C and dried for 24 hours, and then calcined at 450°C in a nitrogen atmosphere for 6 hours to obtain a catalyst for use.

[0039] Comparative Example 7

[0040] The same amount of ferric chloride, cobalt chloride and anhydrous ethanol as in Example 2 were added into a beaker at once and stirred for 15 minutes, and 18 g of activated carbon was added and placed in an ultrasonic cleaning instrument for ultrasonic treatment for 90 minutes at an ultrasonic frequency of 25 kHz. After the ultrasonic treatment, the mixture was first soaked at room temperature for 12 hours, then the temperature was gradually increased to 100° C. and dried for 24 hours, and then calcined at 450° C. in an argon atmosphere for 4 hours to obtain a catalyst for use.

[0041] Comparative Example 9

[0042] The same amount of copper chloride and isopropanol as in Example 1 were added into a beaker at once and stirred for 15 minutes, 10 g of alumina was added and ultrasonic cleaning was performed for 90 minutes at an ultrasonic frequency of 28 kHz. After the ultrasonic treatment, the mixture was first soaked at room temperature for 12 hours, then the temperature was gradually increased to 120°C and dried for 24 hours, and then calcined at 450°C in a nitrogen atmosphere for 6 hours to obtain a catalyst for use.

[0043] Comparative Example 10

[0044] The same amount of copper chloride and isopropanol as in Example 1 were added into a beaker at once and stirred for 15 minutes, 10 g of ZSM-5 molecular sieve was added and placed in an ultrasonic cleaner for ultrasonic treatment for 90 minutes, and the ultrasonic frequency was 28 kHz. After the ultrasonic treatment, the mixture was first soaked at room temperature for 12 hours, then the temperature was gradually increased to 120°C and dried for 24 hours, and then calcined at 450°C in a nitrogen atmosphere for 6 hours to obtain a catalyst for use.

[0045] Catalyst performance test methods

[0046] First, the catalyst is pressed and crushed into particles of the required mesh size, and then a certain amount of catalyst is loaded into the stainless steel reaction tube according to the requirements of each experiment, and the rest is filled with quartz sand. The reaction tube is placed in the reactor and fixed, and nitrogen is introduced to check the entire device for leaks and then the temperature is raised to the reaction temperature. The gas flow rate is 200h -1 About, when the catalyst is used for the first time, chlorine should be passed through for activation. Then start the micro metering pump, mix the liquid 2-chloropyridine with nitrogen after passing through the flow meter and then pump it into the preheater, mix it with chlorine after vaporization and pass it into the reactor for reaction, the molar ratio of 2-chloropyridine to chlorine is about 1:4, and the reaction product exists in the reactor in a gaseous state and flows out of the reactor with the reaction gas flow. Most of the products are directly converted into solid state after cooling and collected. After the reaction is completed, the product is analyzed by gas chromatography. The catalyst performance results are shown in Table 1.

[0047] Table 1 Catalyst performance test results

[0048] catalyst Reaction temperature / ℃ Running time / h Conversion rate / % Yield / % Example 1 330 200 97.9 71.1 Example 2 350 200 96.2 65.5 Example 3 350 200 96.7 59.3 Example 4 370 200 95.1 72.2 Example 5 370 200 99.3 79.9 Comparative Example 1 330 200 84.7 47.5 Comparative Example 2 350 200 81.3 42.9 Comparative Example 3 350 200 87.6 38.8 Comparative Example 4 370 200 81.7 51.9 Comparative Example 5 370 200 91.7 45.2 Comparative Example 6 330 200 82.2 47.2 Comparative Example 7 350 200 71.7 52.5 Comparative Example 8 330 200 77.3 41.5 Comparative Example 9 330 200 67.5 35.7

[0049] As shown in the above table, the use of the catalyst of the present invention has a significant improvement in conversion rate and yield.

[0050] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A catalyst for preparing 2,3-dichloropyridine, characterized in that: It comprises catalyst active components, aluminum oxide carrier and boron nitride; based on the total mass of the catalyst, the mass percentage of the catalyst active components is 5-20%, the mass percentage of the aluminum oxide carrier is 60-80%, and the mass percentage of the boron nitride is 5-15%.

2. A method for preparing a catalyst for preparing 2,3-dichloropyridine according to claim 1, characterized in that: The following steps are involved: The active components of the catalyst are dissolved in a solvent and stirred evenly, and then a template, nitric acid and boron nitride are added and stirred continuously, and then aluminum salt is added and placed in an ultrasonic cleaner to be fully dissolved by ultrasonication, and a sol is obtained after dissolution, and then an alumina-supported catalyst is obtained after aging, drying and calcination.

3. A method for preparing a catalyst for preparing 2,3-dichloropyridine according to claim 2, characterized in that: The catalytically active components are loaded on an alumina carrier, and the catalytically active components are selected from one or two of ferric chloride, cupric chloride, zinc chloride, cobalt chloride, lanthanum chloride and cerium chloride.

4. The method for preparing a catalyst for preparing 2,3-dichloropyridine according to claim 2, characterized in that: The aluminum salts include aluminum isopropoxide, aluminum sec-butoxide, and aluminum triethoxide.

5. The method for preparing a catalyst for preparing 2,3-dichloropyridine according to claim 2, characterized in that: The boron nitride is one of hexagonal boron nitride, cubic boron nitride, rhombohedral boron nitride and wurtzite boron nitride.

6. The method for preparing a catalyst for preparing 2,3-dichloropyridine according to claim 2, characterized in that: The solvent is anhydrous methanol, anhydrous ethanol or isopropanol, the template agent is polyoxyethylene-polyoxypropylene copolymer, polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer or hexadecyltrimethylammonium bromide, and the mass ratio of the template agent to the aluminum salt is 1:5-1:

15.

7. The method for preparing a catalyst for preparing 2,3-dichloropyridine according to claim 5, characterized in that: The ultrasonic treatment time is 60-90 minutes, and the ultrasonic frequency is 20-40 kHz.

8. A method for preparing a catalyst for preparing 2,3-dichloropyridine according to claim 5 or 7, characterized in that: The sol is aged at 40-70°C for 8-16 hours to gel, and then dried at 90-150°C for 4-48 hours.

9. The method for preparing a catalyst for preparing 2,3-dichloropyridine according to claim 8, characterized in that: The catalyst is calcined at a temperature of 350-500° C. for a time of 2-8 hours. The catalyst is calcined in an atmosphere of nitrogen, argon or other inert gases to prevent oxidation of active components.

10. The method for preparing a catalyst for preparing 2,3-dichloropyridine according to claim 8, characterized in that: The catalyst is calcined at a temperature of 400-450° C. and for a time of 4-6 hours. The catalyst is calcined in an atmosphere of nitrogen, argon or other inert gases to prevent oxidation of active components.