Catalyst for pyridine synthesis, preparation method and application

Abstract

The invention relates to the field of pyridine and particularly provides a catalyst for pyridine synthesis as well as a preparation method and application thereof. The catalyst for pyridine synthesis is prepared from the following raw materials in parts by weight: 2-10 parts of metal salt and / or metal oxide, 10-30 parts of molecular sieve, 1-5 parts of titanium dioxide, 5-20 parts of kaolin, 20-40 parts of alumina sol and 20-40 parts of water. The catalyst for pyridine synthesis is prepared from the metal salt and / or the metal oxide, the molecular sieve, the titanium dioxide, the kaolin, the aluminum sol and the water according to a specific ratio, so that the titanium modified catalyst is obtained, and the catalyst is good in catalytic performance and high in pyridine yield and can be used for catalyzing acetaldehyde and ammonia to obtain 2-methylpyridine and 4-methylpyridine.

Description

Technical Field

[0001] The present invention relates to the field of pyridine synthesis, and in particular, to a catalyst for pyridine synthesis, a preparation method and an application thereof. Background Art

[0002] Pyridine series raw materials are important organic raw materials for producing high-value-added fine chemical products, and are widely used in fields such as medicine, pesticides, essence and fragrance, and feed additives. 2-Methylpyridine is a raw material for synthesizing important pesticide intermediates, and vinylpyridine produced from 2-methylpyridine is also an important rubber auxiliary. Therefore, 2-methylpyridine has great market potential. 4-Methylpyridine is used in the pharmaceutical industry to synthesize isoniazid. As an efficient anti-tuberculosis drug, isoniazid has very good development prospects. In addition, 4-methylpyridine is also widely used in fields such as dyes, pesticides, and synthetic resins.

[0003] Early pyridine bases were often extracted from coal coking by-products, which had problems of low yield and poor product purity. With the increasing demand for pyridine bases in various fields, researchers developed the aldehyde-ammonia condensation reaction, and the process route gradually matured. At present, most pyridine bases are obtained by condensation reaction of aldehydes and ammonia under the action of a catalyst, and the catalytic performance of the catalyst is crucial for the yield of pyridine and its derivatives.

[0004] In view of this, the present invention is specifically proposed. Summary of the Invention

[0005] The purpose of the present invention is to provide a catalyst for pyridine synthesis, a preparation method and an application thereof. The catalyst for pyridine synthesis has excellent catalytic performance and high pyridine yield.

[0006] In order to achieve the above object of the present invention, the following technical solutions are specifically adopted:

[0007] In the first aspect, the present invention provides a catalyst for pyridine synthesis, which is prepared from the following raw materials in parts by weight:

[0008] 2-10 parts of metal salt and / or metal oxide, 10-30 parts of molecular sieve, 1-5 parts of titanium dioxide, 5-20 parts of kaolin, 20-40 parts of aluminum sol and 20-40 parts of water.

[0009] As a further preferred technical solution, the catalyst is prepared from the following raw materials in parts by weight:

[0010] 2-5 parts of metal salt and / or metal oxide, 15-30 parts of molecular sieve, 2-5 parts of titanium dioxide, 10-20 parts of kaolin, 30-40 parts of aluminum sol and 20-30 parts of water.

[0011] As a further preferred technical solution, the metal salt includes cobalt salt, chromium salt or bismuth salt, and the metal oxide includes cobalt oxide, chromium oxide or bismuth oxide.

[0012] As a further preferred technical solution, the molecular sieve is ZSM-5 molecular sieve.

[0013] As a further preferred technical solution, the diameter of the catalyst is 70-500 microns.

[0014] In a second aspect, the present invention provides a preparation method of the above-mentioned catalyst for pyridine synthesis, comprising the following steps:

[0015] Mix the raw materials in the formula amount and then ball mill to prepare a slurry, and then obtain a catalyst precursor by spray drying, and then calcine the catalyst precursor to obtain the catalyst for pyridine synthesis.

[0016] As a further preferred technical solution, the ball milling time is 2-5 h.

[0017] As a further preferred technical solution, the solid content in the slurry is 25%-45%, the temperature of the slurry is lower than 80°C, and the water content of the catalyst precursor is 1%-5%.

[0018] As a further preferred technical solution, the calcination temperature is 450°C-800°C, and the calcination time is 3-6 h.

[0019] In a third aspect, the present invention provides an application of the above-mentioned catalyst for pyridine synthesis or a catalyst prepared by using the preparation method of the above-mentioned catalyst for pyridine synthesis in pyridine synthesis.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0021] The catalyst for pyridine synthesis provided by the present invention is prepared by using a metal salt and / or metal oxide, molecular sieve, titanium dioxide, kaolin, aluminum sol and water in a specific ratio, so as to obtain a titanium-modified catalyst. This catalyst has good catalytic performance and high pyridine yield, and can be used to catalyze acetaldehyde and ammonia to obtain 2-methylpyridine and 4-methylpyridine.

[0022] The preparation method of the catalyst for pyridine synthesis provided by the present invention adopts a one-step method. The preparation process is simple and feasible, has good repeatability, and is easy to be scaled up for industrial production. Further, the density and strength of the catalyst can be further improved by high-intensity ball milling. Detailed Embodiments

[0023] The embodiments of the present invention will be described in detail below in conjunction with examples. However, those skilled in the art will understand that the following examples are only used to illustrate the present invention and should not be regarded as limiting the scope of the present invention. For those not specified in the examples, they are carried out under conventional conditions or conditions recommended by the manufacturer.

[0024] As an aspect of the present invention, the present invention provides a catalyst for pyridine synthesis, and the catalyst is prepared from the following raw materials in parts by weight:

[0025] Metal salt and / or metal oxide 2 - 10 parts, molecular sieve 10 - 30 parts, titanium dioxide 1 - 5 parts, kaolin 5 - 20 parts, aluminum sol 20 - 40 parts, and water 20 - 40 parts.

[0026] Among them, by weight, the metal salt and / or metal oxide includes but is not limited to 2 parts, 3 parts, 4 parts, 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, or 10 parts; the molecular sieve includes but is not limited to 10 parts, 11 parts, 12 parts, 13 parts, 14 parts, 15 parts, 16 parts, 17 parts, 18 parts, 19 parts, 20 parts, 21 parts, 22 parts, 23 parts, 24 parts, 25 parts, 26 parts, 27 parts, 28 parts, 29 parts, or 30 parts; the titanium dioxide includes but is not limited to 1 part, 1.5 parts, 2 parts, 2.5 parts, 3 parts, 3.5 parts, 4 parts, 4.5 parts, or 5 parts; the kaolin includes but is not limited to 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, 10 parts, 11 parts, 12 parts, 13 parts, 14 parts, 15 parts, 16 parts, 17 parts, 18 parts, 19 parts, or 20 parts; the aluminum sol includes but is not limited to 20 parts, 21 parts, 22 parts, 23 parts, 24 parts, 25 parts, 26 parts, 27 parts, 28 parts, 29 parts, 30 parts, 31 parts, 32 parts, 33 parts, 34 parts, 35 parts, 36 parts, 37 parts, 38 parts, 39 parts, or 40 parts; the water includes but is not limited to 20 parts, 21 parts, 22 parts, 23 parts, 24 parts, 25 parts, 26 parts, 27 parts, 28 parts, 29 parts, 30 parts, 31 parts, 32 parts, 33 parts, 34 parts, 35 parts, 36 parts, 37 parts, 38 parts, 39 parts, or 40 parts.

[0027] The above catalyst for pyridine synthesis is made by using specific ratios of metal salt and / or metal oxide, molecular sieve, titanium dioxide, kaolin, aluminum sol, and water, thereby obtaining a titanium - modified catalyst. This catalyst has good catalytic performance and high pyridine yield, and can be used to catalyze acetaldehyde and ammonia to obtain 2 - methylpyridine and 4 - methylpyridine.

[0028] In an alternative embodiment, the catalyst is prepared from the following raw materials in parts by weight: 2 - 5 parts of metal salt and / or metal oxide, 15 - 30 parts of molecular sieve, 2 - 5 parts of titanium dioxide, 10 - 20 parts of kaolin, 30 - 40 parts of aluminum sol, and 20 - 30 parts of water. When the ratio of each raw material is within the above range, the catalytic performance of the obtained catalyst is better.

[0029] In an alternative embodiment, the metal salt includes but is not limited to nitrate, chloride, carbonate, and sulfate. The metal oxide includes cobalt oxide, chromium oxide, or bismuth oxide.

[0030] In an alternative embodiment, the molecular sieve is ZSM-5 molecular sieve. ZSM-5 has a unique pore structure, good catalytic performance, and hydrothermal stability. Therefore, it is beneficial to improve the catalytic performance when used in this catalyst.

[0031] In an alternative embodiment, the diameter of the catalyst is 70 - 500 microns. The above diameters include but are not limited to 70 - 100 microns, 100 - 150 microns, 150 - 200 microns, 200 - 250 microns, 300 - 350 microns, 350 - 400 microns, or 450 - 500 microns, etc.

[0032] As another aspect of the present invention, the present invention provides a preparation method of the above-mentioned catalyst for pyridine synthesis, comprising the following steps:

[0033] Mix the raw materials in the formula amount and then ball mill to prepare a slurry, and then obtain a catalyst precursor by spray drying, and then calcine the catalyst precursor to obtain the catalyst for pyridine synthesis.

[0034] In an alternative embodiment, the time of ball milling is 2 - 5 h. The above ball milling time includes but is not limited to 2 h, 2.5 h, 3 h, 3.5 h, 4 h, 4.5 h, or 5 h. By high-intensity ball milling, the density and strength of the catalyst can be further improved.

[0035] In an alternative embodiment, the solid content in the slurry is 25% - 45%, the temperature of the slurry is lower than 80 °C, and the water content of the catalyst precursor is 1% - 5%. The above solid content in the slurry includes but is not limited to 25%, 26%, 28%, 30%, 32%, 34%, 36%, 38%, 40%, 42%, or 45%; the temperature of the slurry includes but is not limited to 5 °C, 10 °C, 15 °C, 20 °C, 25 °C, 30 °C, 35 °C, 40 °C, 45 °C, 50 °C, 55 °C, 60 °C, 65 °C, 70 °C, 75 °C, or 80 °C; the above water content of the catalyst precursor includes but is not limited to 1%, 2%, 3%, 4%, or 5%.

[0036] In an alternative embodiment, the calcination temperature is 450°C - 800°C, and the calcination time is 3 - 6 h. The above calcination temperature includes but is not limited to 450°C, 500°C, 550°C, 600°C, 650°C, 700°C, 750°C or 800°C. The calcination time includes but is not limited to 3 h, 3.5 h, 4 h, 4.5 h, 5 h, 5.5 h or 6 h. The above calcination temperature is relatively reasonable. If the calcination temperature is too low, the purpose of high-temperature calcination activation cannot be achieved, and the catalyst activity is too low. If the temperature is too high, the catalyst is likely to be deactivated.

[0037] The preparation method of the catalyst for pyridine synthesis provided by the present invention adopts a one-step method. The preparation process is simple and feasible, has good repeatability, and is easy to scale up for industrial production. Further, the density and strength of the catalyst can be further improved by high-intensity ball milling.

[0038] As another aspect of the present invention, the present invention provides an application of the above catalyst in pyridine synthesis. Applying the above catalyst in pyridine synthesis, especially in the condensation reaction of acetaldehyde and ammonia to synthesize 2-methylpyridine and 4-methylpyridine, can effectively improve the pyridine synthesis yield.

[0039] The following further describes the present invention in detail with reference to examples and comparative examples. M

[0040] Example 1

[0041] A catalyst for pyridine synthesis, the preparation process is as follows:

[0042] 50 g of cobalt nitrate, 500 g of molecular sieve, 30 g of titanium dioxide, 250 g of kaolin, 700 g of aluminum sol, and 650 g of water are stirred evenly until completely dissolved. The obtained slurry is ball milled for 3 h to obtain a milky white suspension. The temperature of the slurry is 70°C, and the solid content is 28%. The above suspension is transferred to a spray drying tower and centrifugally spray dried to obtain a titanium-loaded ZSM-5 molecular sieve catalyst precursor. The water content of the precursor is 2.16%. The catalyst precursor is placed in a 700°C calcination furnace for high-temperature calcination activation for 5 h, and then naturally cooled to room temperature in the air to obtain catalyst A.

[0043] Performance evaluation of the catalyst:

[0044] The prepared catalyst is used in the reaction of acetaldehyde and ammonia condensation to produce 2-methylpyridine and 4-methylpyridine. In a fluidized bed reactor, the catalyst filling amount is 175 g, the reaction temperature is 420°C, and the molar ratio of acetaldehyde to ammonia is 1:4.2. The product is analyzed by gas chromatography, and the reaction results are shown in Table 1.

[0045] Example 2

[0046] A catalyst for pyridine synthesis, the preparation process is as follows:

[0047] 50 g of cobalt nitrate, 500 g of molecular sieve, 50 g of titanium dioxide, 250 g of kaolin, 700 g of aluminum sol, and 650 g of water were stirred evenly until completely dissolved. The obtained slurry was ball-milled for 3 h to obtain a milky white suspension. The temperature of the slurry was 70.8 °C, and the solid content was 32%; the above suspension was transferred to a spray drying tower and spray-dried centrifugally to obtain a titanium-loaded ZSM-5 molecular sieve catalyst precursor. The water content of the precursor was 1.73%; the catalyst precursor was placed in a calcination furnace at 700 °C for high-temperature calcination and activation for 5 h, and then naturally cooled to room temperature in the air to obtain catalyst B.

[0048] The performance evaluation of the catalyst was the same as that in Example 1.

[0049] Example 3

[0050] 50 g of cobalt nitrate, 500 g of molecular sieve, 70 g of titanium dioxide, 250 g of kaolin, 700 g of aluminum sol, and 650 g of water were stirred evenly until completely dissolved. The obtained slurry was ball-milled for 3 h to obtain a milky white suspension. The temperature of the slurry was 71.7 °C, and the solid content was 35%; the above suspension was transferred to a spray drying tower and spray-dried centrifugally to obtain a titanium-loaded ZSM-5 molecular sieve catalyst precursor. The water content of the precursor was 1.73%; the catalyst precursor was placed in a calcination furnace at 700 °C for high-temperature calcination and activation for 5 h, and then naturally cooled to room temperature in the air to obtain catalyst C.

[0051] The performance evaluation of the catalyst was the same as that in Example 1.

[0052] Example 4

[0053] The catalyst was the same as that in Example 1.

[0054] Performance evaluation of the catalyst:

[0055] The prepared catalyst was used in the reaction of acetaldehyde and ammonia condensation to produce 2-methylpyridine and 4-methylpyridine. In a fluidized bed reactor, the catalyst filling amount was 175 g, the reaction temperature was 400 °C, and the molar ratio of acetaldehyde to ammonia was 1:4.2. The product was analyzed by gas chromatography, and the reaction results are shown in Table 1.

[0056] Example 5

[0057] The catalyst was the same as that in Example 2.

[0058] The performance evaluation of the catalyst was the same as that in Example 4.

[0059] Example 6

[0060] The catalyst was the same as that in Example 3

[0061] The performance evaluation of the catalyst was the same as that in Example 4.

[0062] Comparative Example 1

[0063] A catalyst for pyridine synthesis, and its preparation process is as follows:

[0064] 50 g of cobalt nitrate, 500 g of molecular sieve, 250 g of kaolin, 700 g of aluminum sol, and 650 g of water are stirred evenly until completely dissolved. The obtained slurry is ball-milled to obtain a milky white suspension. The temperature of the slurry is 67 °C, and the solid content is 25%; the above suspension is transferred to a spray drying tower and spray-dried centrifugally to obtain a catalyst precursor, and the water content of the precursor is 2.58%; the catalyst precursor is placed in a calcination furnace at 700 °C for high-temperature calcination and activation for 5 h, and then naturally cooled to room temperature in the air to obtain catalyst D.

[0065] The performance evaluation of the catalyst is the same as that in Example 1.

[0066] Comparative Example 2

[0067] The catalyst is the same as that in Comparative Example 1.

[0068] The performance evaluation of the catalyst is the same as that in Example 4.

[0069] Comparative Example 3

[0070] A catalyst for pyridine synthesis, and its preparation process is as follows:

[0071] 50 g of cobalt nitrate, 500 g of molecular sieve, 300 g of titanium dioxide, 250 g of kaolin, 700 g of aluminum sol, and 650 g of water are stirred evenly until completely dissolved. The obtained slurry is ball-milled to obtain a milky white suspension. The temperature of the slurry is 78 °C, and the solid content is 43%; the above suspension is transferred to a spray drying tower and spray-dried centrifugally to obtain a titanium-loaded ZSM-5 molecular sieve catalyst precursor, and the water content of the precursor is 0.44%; the catalyst precursor is placed in a calcination furnace at 700 °C for high-temperature calcination and activation for 5 h, and then naturally cooled to room temperature in the air to obtain catalyst E.

[0072] The performance evaluation of the catalyst is the same as that in Example 1.

[0073] Table 1 Comparison of the performance of the condensation reaction of acetaldehyde and ammonia in Examples 1-6 and Comparative Examples 1-3

[0074]

[0075]

[0076] From the above data, it can be concluded that the titanium-containing catalyst B has the best yield and the catalyst is better. The yield of the catalyst first increases and then decreases with the increase of the titanium oxide content, and the optimal ratio of titanium content in the formulation is 2.27%. Comparing at different temperatures, it can be seen that the reaction yield is better at 420 °C, and the ratio of 4-methylpyridine / 2-methylpyridine will increase when the reaction temperature decreases.

[0077] After selecting the titanium dioxide content, the metal salt and / or metal oxide components and the silica-alumina ratio of the molecular sieve are investigated. The silica-alumina ratio of the molecular sieve without special indication is defaulted to 140.

[0078] Example 7

[0079] A catalyst for pyridine synthesis, and its preparation process is as follows:

[0080] 50 g of chromium nitrate, 500 g of molecular sieve, 50 g of titanium dioxide, 250 g of kaolin, 700 g of aluminum sol, and 650 g of water are stirred evenly until completely dissolved. The obtained slurry is ball-milled for 3 h to obtain a milky white suspension. The temperature of the slurry is 70.8 °C, and the solid content is 32%; the above suspension is transferred to a spray drying tower and centrifugally spray-dried to obtain a titanium-loaded ZSM-5 molecular sieve catalyst precursor. The water content of the precursor is 1.73%; the catalyst precursor is placed in a calcination furnace at 700 °C for high-temperature calcination and activation for 5 h, and then naturally cooled to room temperature in the air to obtain catalyst F.

[0081] The performance evaluation of the catalyst is the same as that in Example 1.

[0082] Example 8

[0083] A catalyst for pyridine synthesis, and its preparation process is as follows:

[0084] 50 g of bismuth nitrate, 500 g of molecular sieve, 50 g of titanium dioxide, 250 g of kaolin, 700 g of aluminum sol, and 650 g of water are stirred evenly until completely dissolved. The obtained slurry is ball-milled for 3 h to obtain a milky white suspension. The temperature of the slurry is 70.8 °C, and the solid content is 32%; the above suspension is transferred to a spray drying tower and centrifugally spray-dried to obtain a titanium-loaded ZSM-5 molecular sieve catalyst precursor. The water content of the precursor is 1.73%; the catalyst precursor is placed in a calcination furnace at 700 °C for high-temperature calcination and activation for 5 h, and then naturally cooled to room temperature in the air to obtain catalyst G.

[0085] The performance evaluation of the catalyst is the same as that in Example 1.

[0086] Example 9

[0087] A catalyst for pyridine synthesis, and its preparation process is as follows:

[0088] 50 g of bismuth nitrate, 500 g of molecular sieve (silica-alumina ratio of 110), 50 g of titanium dioxide, 250 g of kaolin, 700 g of aluminum sol, and 650 g of water were stirred evenly until completely dissolved. The resulting slurry was ball-milled for 3 h to obtain a milky white suspension. The temperature of the slurry was 70.8 °C, and the solid content was 32%; the above suspension was transferred to a spray drying tower and spray-dried centrifugally to obtain a titanium-loaded ZSM-5 molecular sieve catalyst precursor with a water content of 1.73%; the catalyst precursor was placed in a calcination furnace at 700 °C for high-temperature calcination and activation for 5 h, and then naturally cooled to room temperature in the air to obtain catalyst H.

[0089] The performance evaluation of the catalyst was the same as that in Example 1.

[0090] Example 10

[0091] A catalyst for pyridine synthesis, and its preparation process is as follows:

[0092] 50 g of bismuth nitrate, 500 g of molecular sieve (silica-alumina ratio of 170), 50 g of titanium dioxide, 250 g of kaolin, 700 g of aluminum sol, and 650 g of water were stirred evenly until completely dissolved. The resulting slurry was ball-milled for 3 h to obtain a milky white suspension. The temperature of the slurry was 70.8 °C, and the solid content was 32%; the above suspension was transferred to a spray drying tower and spray-dried centrifugally to obtain a titanium-loaded ZSM-5 molecular sieve catalyst precursor with a water content of 1.73%; the catalyst precursor was placed in a calcination furnace at 700 °C for high-temperature calcination and activation for 5 h, and then naturally cooled to room temperature in the air to obtain catalyst I.

[0093] The performance evaluation of the catalyst was the same as that in Example 1.

[0094] Table 2 Comparison of the performance of the acetaldehyde and ammonia condensation reactions in Examples 7 - 10

[0095]

[0096] From the above data, it can be concluded that catalyst G with a metal component of bismuth has the best yield and better catalytic performance. As the silica-alumina ratio of the molecular sieve increases, the yield first increases and then decreases, and it is optimal when the silica-alumina ratio is 140. The total yield of pyridine derivatives and the ratio of 4-methylpyridine / 2-methylpyridine will increase.

[0097] Although the present invention has been illustrated and described with specific examples, it should be realized that many other changes and modifications can be made without departing from the spirit and scope of the present invention. Therefore, this means that all such changes and modifications within the scope of the present invention are included in the appended claims.

Claims

1. A catalyst for pyridine synthesis, characterized in that The catalyst is prepared using the following raw materials in parts by weight: 2-10 parts of metal salt and / or metal oxide, 10-30 parts of molecular sieve, 1-5 parts of titanium dioxide, 5-20 parts of kaolin, 20-40 parts of aluminum sol and 20-40 parts of water.

2. The catalyst for pyridine synthesis according to claim 1, characterized in that The catalyst is prepared using the following raw materials in parts by weight: 2-5 parts of metal salt and / or metal oxide, 15-30 parts of molecular sieve, 2-5 parts of titanium dioxide, 10-20 parts of kaolin, 30-40 parts of aluminum sol and 20-30 parts of water.

3. The catalyst for pyridine synthesis according to claim 1, characterized in that The metal salt includes a cobalt salt, a chromium salt or a bismuth salt, and the metal oxide includes a cobalt oxide, a chromium oxide or a bismuth oxide.

4. The catalyst for pyridine synthesis according to claim 1, characterized in that The molecular sieve is ZSM-5 molecular sieve.

5. The catalyst for pyridine synthesis according to any one of claims 1 to 4, characterized in that The catalyst has a diameter of 70-500 microns.

6. The method for preparing a catalyst for pyridine synthesis according to any one of claims 1 to 5, characterized in that: The following steps are involved: The raw materials in the formula amount are mixed and ball-milled to prepare slurry, which is then spray-dried to obtain a catalyst precursor, and then the catalyst precursor is calcined to obtain the catalyst for pyridine synthesis.

7. The method for preparing a catalyst for pyridine synthesis according to claim 6, characterized in that: The ball milling time is 2-5h.

8. The method for preparing a catalyst for pyridine synthesis according to claim 6, characterized in that: The solid content of the slurry is 25%-45%, the temperature of the slurry is lower than 80° C., and the water content of the catalyst precursor is 1%-5%.

9. The method for preparing a catalyst for pyridine synthesis according to any one of claims 6 to 8, characterized in that: The calcination temperature is 450° C.-800° C., and the calcination time is 3-6 hours.

10. Use of the catalyst for pyridine synthesis according to any one of claims 1 to 5 or a catalyst prepared by the method for preparing the catalyst for pyridine synthesis according to any one of claims 6 to 9 in pyridine synthesis.

Images