Pyridine catalyst stability test method and screening method

Abstract

The present application relates to the field of catalyst testing, and in particular, a pyridine catalyst stability testing method and screening method are provided.The pyridine catalyst stability testing method comprises the following steps: S1, placing a pyridine catalyst in a fluidized bed reactor; S2, feeding water with a feed pump, the water is contacted with the pyridine catalyst after vaporization, the time when the water vapor contacts with the pyridine catalyst is taken as the starting point, the water is treated for 10-60h, and then the pyridine catalyst after hydrothermal treatment is removed; S3, placing the pyridine catalyst after hydrothermal treatment in another fluidized bed reactor for reaction, feeding formaldehyde and acetaldehyde, and simultaneously feeding ammonia; S4, sampling once every set time interval, recording the weight of the feed and the discharge, and calculating the yield.The present application has a short testing period, and can effectively screen the required catalyst.

Description

Technical Field

[0001] This invention relates to the field of catalyst testing, and more specifically, to a method for testing and screening the stability of pyridine catalysts. Background Technology

[0002] Molecular sieve catalysts are widely used in the process of aldehyde-ammonia condensation to produce pyridine. However, the catalyst's lifespan is relatively short. As the industrial plant operates, the activity of the molecular sieve catalyst rapidly declines due to carbon deposition, resulting in a significant decrease in pyridine yield. Thermal stability and hydrothermal stability are important indicators for evaluating catalyst performance. Fresh catalysts, having not undergone the reaction process, do not have representative initial activity. Therefore, it is essential to study the stability of molded catalysts by investigating hydrothermal treatment conditions.

[0003] To simulate the decline in catalyst activity during industrial processes, catalysts are typically subjected to pre-treatment with hydrothermal heat under highly demanding conditions. The catalyst is fluidized with air at 500-800°C. Under these high temperatures and steam conditions, the physicochemical and catalytic properties of the molecular sieve catalyst change, allowing the catalyst to reach equilibrium activity. In existing technologies, the hydrothermal treatment unit and fluidized bed reactor for pyridine catalysts are usually integrated into a single unit, resulting in a long reaction cycle. Therefore, finding a simple method to determine the stability of pyridine catalysts, shorten the reaction cycle, and rapidly obtain stable pyridine catalyst properties is a problem that industry seeks to solve.

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

[0005] The purpose of this invention is to provide a method for testing and screening the stability of pyridine catalysts, so as to solve the problems of long testing cycles and difficult catalyst screening in the prior art.

[0006] In order to achieve the above-mentioned objectives of the present invention, the following technical solution is adopted:

[0007] In a first aspect, the present invention provides a method for testing the stability of a pyridine catalyst, comprising:

[0008] S1. Place the pyridine catalyst in a fluidized bed reactor;

[0009] S2: Water is introduced by a feed pump. After the water is vaporized, it comes into contact with the pyridine catalyst. The contact time between the water vapor and the pyridine catalyst is taken as the starting point. Water treatment is carried out for 10-60 hours, and then the hydrothermally treated pyridine catalyst is removed.

[0010] S3. The hydrothermally treated pyridine catalyst is placed in another fluidized bed reactor for reaction, with formaldehyde and acetaldehyde as feed and ammonia gas introduced at the same time.

[0011] S4. Take a sample at a set time interval, record the weight of the feed and discharge, and calculate the yield.

[0012] As a further preferred technical solution, the temperature inside the fluidized bed reactor in S1 is 500-800℃.

[0013] As a further preferred technical solution, in step S1, after placing the pyridine catalyst in the fluidized bed reactor, the step of introducing air or nitrogen at a rate of 1-5 L / min is further included.

[0014] As a further preferred technical solution, the flow rate of the inlet water in S2 is 2-8 mL / min.

[0015] As a further preferred technical solution, the temperature inside the other fluidized bed reactor in S3 is 350-500℃.

[0016] As a further preferred technical solution, the feed flow rate in S3 is 2-10 mL / min.

[0017] As a further preferred technical solution, the ammonia flow rate in S3 is 1-5 L / min.

[0018] Secondly, the present invention provides a method for screening pyridine catalysts, comprising:

[0019] The pyridine catalyst was tested using the above-mentioned stability test method, with water treatment times of 30h and 60h, respectively.

[0020] Based on the test results, determine whether the pyridine catalyst is a substandard catalyst, a qualified catalyst, or a high-quality catalyst.

[0021] As a further preferred technical solution, determining whether the pyridine catalyst is a substandard catalyst, a qualified catalyst, or a high-quality catalyst based on the test results includes:

[0022] If the yield decreases more than the first preset range after testing with a water treatment time of 30 hours, the pyridine catalyst is determined to be a substandard catalyst.

[0023] If the yield does not decrease or decreases within the first preset range after testing with a water treatment time of 30 hours, and the yield decreases beyond the second preset range after testing with a water treatment time of 60 hours, then the pyridine catalyst is determined to be a qualified catalyst.

[0024] If, after testing for 60 hours of water treatment, the yield decreases within the second preset range, then the pyridine catalyst is determined to be a high-quality catalyst.

[0025] As a further preferred technical solution

[0026] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0027] The method for testing the stability of pyridine catalysts provided by this invention first places the pyridine catalyst in a fluidized bed reactor for water-induced destructive treatment, and then uses another fluidized bed reactor to evaluate and analyze the performance of the treated catalyst. This method can quickly verify the hydrothermal stability of pyridine catalysts and has a short testing cycle.

[0028] The pyridine catalyst screening method provided by this invention adopts the above-mentioned pyridine catalyst stability test method, except that the water treatment time is 30h and 60h respectively. Then, based on the test results, it is determined whether the pyridine catalyst is a substandard catalyst, a qualified catalyst, or a high-quality catalyst. This method can effectively screen out the desired catalyst. Detailed Implementation

[0029] The embodiments of the present invention will be described in detail below with reference to examples. However, those skilled in the art will understand that the following examples are for illustrative purposes only and should not be considered as limiting the scope of the invention. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer shall apply.

[0030] As one aspect of the present invention, the present invention provides a method for testing the stability of pyridine catalysts, comprising:

[0031] S1. Place the pyridine catalyst in a fluidized bed reactor;

[0032] S2: Water is introduced by a feed pump. After the water is vaporized, it comes into contact with the pyridine catalyst. The contact time between the water vapor and the pyridine catalyst is taken as the starting point. Water treatment is carried out for 10-60 hours, and then the hydrothermally treated pyridine catalyst is removed.

[0033] S3. The hydrothermally treated pyridine catalyst is placed in another fluidized bed reactor for reaction, with formaldehyde and acetaldehyde as feed and ammonia gas introduced at the same time.

[0034] S4. Take a sample at a set time interval, record the weight of the feed and discharge, and calculate the yield.

[0035] A fluidized bed reactor is a reactor that utilizes the passage of gas or liquid through a layer of particulate solids, suspending the solid particles and enabling gas-solid or liquid-solid phase reactions. When used in gas-solid systems, it is also called a boiling bed reactor. Optionally, a fluidized bed reactor consists of a preheater, reactor, condenser, feed tank, receiving tank, ammonia flow meter, a chiller, and a feed pump.

[0036] Pyridine catalysts are catalysts that catalyze the aldehyde-ammonia condensation reaction of formaldehyde, acetaldehyde, and ammonia to produce pyridine bases.

[0037] Yield refers to the ratio of the mass of the target product (pyridine base) produced per unit time to the mass of the feedstock (formaldehyde and acetaldehyde).

[0038]

[0039] Optionally, in step S2, the water is preheated by a preheater before vaporization.

[0040] Optionally, in step S3, formaldehyde and acetaldehyde are placed in the raw material tank beforehand. The weight ratio of formaldehyde to acetaldehyde can be any existing ratio that achieves the synthesis objective; this invention does not impose any particular limitation on this.

[0041] Optionally, the above-mentioned time interval can be set to, for example, 1 hour or 2 hours.

[0042] Optionally, analysis can be performed using an Agilent 7820 gas chromatograph with a TCD detector.

[0043] Optionally, the cooling temperature of the fluidized bed reactor absorber in step S3 is stabilized at -5°C.

[0044] Optionally, in step S3, a nitrogen-displaced fluidized bed system is used before ammonia is introduced.

[0045] In one optional embodiment, the temperature within the fluidized bed reactor in S1 is 500-800℃. This temperature includes, but is not limited to, 500℃, 520℃, 540℃, 560℃, 580℃, 600℃, 620℃, 640℃, 680℃, 700℃, 720℃, 740℃, 760℃, 780℃, or 800℃. Higher temperatures cause more severe damage to the catalyst and better demonstrate its stability.

[0046] In an optional embodiment, step S1, after placing the pyridine catalyst in the fluidized bed reactor, further includes a step of introducing air or nitrogen at a rate of 1-5 L / min. The flow rate of the air or nitrogen includes, but is not limited to, 1 L / min, 2 L / min, 3 L / min, 4 L / min, or 5 L / min.

[0047] In one optional embodiment, the flow rate of the water entering in step S2 is 2-8 mL / min. This flow rate includes, but is not limited to, 2 mL / min, 3 mL / min, 4 mL / min, 5 mL / min, 6 mL / min, 7 mL / min, or 8 mL / min. A higher water flow rate leads to greater catalyst degradation; if the catalyst still maintains a good yield, it indicates that the catalyst is of excellent quality.

[0048] In an optional embodiment, the temperature in the other fluidized bed reactor in S3 is 350-500°C. This temperature includes, but is not limited to, 350°C, 360°C, 370°C, 380°C, 390°C, 400°C, 410°C, 420°C, 430°C, 440°C, 450°C, 460°C, 470°C, 480°C, 490°C, or 500°C. The reaction of formaldehyde and acetaldehyde to synthesize pyridine base is an endothermic reaction. As the reaction temperature increases, the yield of pyridine base will increase to some extent; however, further increasing the temperature will actually decrease the yield of pyridine base. This is because excessively high temperatures lead to the formation of high-boiling-point substances and increased carbon deposition on the catalyst, thereby reducing the catalytic performance of the catalyst. Temperatures above this range, especially 450°C, are more suitable for the formation of pyridine.

[0049] In one optional embodiment, the feed flow rate in S3 is 2-10 mL / min. The aforementioned feed flow rate includes, but is not limited to, 2 L / min, 3 L / min, 4 L / min, 5 L / min, 6 L / min, 7 L / min, 8 L / min, 9 L / min, or 10 L / min.

[0050] In one optional embodiment, the ammonia flow rate in S3 is 1-5 L / min. The ammonia flow rate includes, but is not limited to, 1 L / min, 2 L / min, 3 L / min, 4 L / min, or 5 L / min.

[0051] Optionally, the reaction is stopped after 6-8 hours in S3, and the pyridine catalyst is removed and regenerated in a muffle furnace.

[0052] Optionally, the regeneration temperature is 400-600℃ and the calcination time is 2-8h.

[0053] The above-mentioned method for testing the stability of pyridine catalysts involves first placing the pyridine catalyst in a fluidized bed reactor for water-induced destructive treatment, and then using another fluidized bed reactor to evaluate and analyze the performance of the treated catalyst. This method can quickly verify the hydrothermal stability of pyridine catalysts with a short testing cycle.

[0054] As another aspect of the present invention, the present invention provides a method for screening pyridine catalysts, comprising:

[0055] The pyridine catalyst was tested using the above-mentioned stability test method, with water treatment times of 30h and 60h, respectively.

[0056] Based on the test results, determine whether the pyridine catalyst is a substandard catalyst, a qualified catalyst, or a high-quality catalyst.

[0057] The pyridine catalyst screening method adopts the above-mentioned pyridine catalyst stability test method, except that the water treatment time is 30h and 60h respectively. Then, based on the test results, it is determined whether the pyridine catalyst is a substandard catalyst, a qualified catalyst, or a high-quality catalyst. This method can effectively screen out the desired catalyst.

[0058] In one optional embodiment, determining whether the pyridine catalyst is a substandard catalyst, a qualified catalyst, or a high-quality catalyst based on the test results includes:

[0059] If the yield decreases more than the first preset range after testing with a water treatment time of 30 hours, the pyridine catalyst is determined to be a substandard catalyst.

[0060] If the yield does not decrease or decreases within the first preset range after testing with a water treatment time of 30 hours, and the yield decreases beyond the second preset range after testing with a water treatment time of 60 hours, then the pyridine catalyst is determined to be a qualified catalyst.

[0061] If, after testing for 60 hours of water treatment, the yield decreases within the second preset range, then the pyridine catalyst is determined to be a high-quality catalyst.

[0062] The first and second preset amplitudes are both relatively small values, for example, 1% to 5%. Within this range, it indicates that the performance of the catalyst does not decrease significantly.

[0063] The present invention will be further described in detail below with reference to embodiments and comparative examples.

[0064] Example 1:

[0065] Hydrothermal treatment: 200g of pyridine catalyst A is loaded into a fluidized bed at 600℃. Air is introduced at 2L / min, and pure water is introduced into the fluidized bed via a preheater at 6mL / min. Timing begins when water vapor enters the fluidized bed and contacts the catalyst. After 10 hours of water supply, the water supply is stopped, and after 10 minutes of blowing, the air supply is stopped and the catalyst is removed.

[0066] Reaction: The dismantled pyridine catalyst, which had undergone hydrothermal treatment for 10 hours, was loaded into a fluidized bed reactor at 450℃. The feed material was a mixture of methyl acetaldehyde, with a feed rate of 2 mL / min and an ammonia gas flow rate of 3 L / min. Samples were taken every hour for gas chromatography analysis of the product content. The weights of the feed material and the output were also recorded to calculate the yield.

[0067] Example 2:

[0068] Hydrothermal treatment: 200g of pyridine catalyst A is loaded into a fluidized bed at 600℃. Air is introduced at 2L / min, and pure water is introduced into the fluidized bed via a preheater at 6mL / min. Timing begins when water vapor enters the fluidized bed and contacts the catalyst. After 20 hours of water supply, the water supply is stopped, and the catalyst is removed after 10 minutes of blowing.

[0069] Reaction: The dismantled pyridine catalyst, which had undergone hydrothermal treatment for 20 hours, was loaded into a fluidized bed reactor at 450℃. The feed material was a mixture of methyl acetaldehyde, with a feed rate of 2 mL / min and an ammonia gas flow rate of 3 L / min. Samples were taken every hour for gas chromatography analysis of the product content. The weights of the feed material and the output material were also recorded to calculate the yield.

[0070] Example 3:

[0071] Hydrothermal treatment: 200g of pyridine catalyst A is loaded into a fluidized bed at 600℃. Air is introduced at 2L / min, and pure water is introduced into the fluidized bed via a preheater at 6mL / min. Timing begins when water vapor enters the fluidized bed and contacts the catalyst. After 30 hours of water supply, the water supply is stopped, and the catalyst is removed after 10 minutes of blowing.

[0072] Reaction: The dismantled pyridine catalyst, which had undergone hydrothermal treatment for 30 hours, was loaded into a fluidized bed reactor at 450℃. The feed material was a mixture of methyl acetaldehyde, with a feed rate of 2 mL / min and an ammonia gas flow rate of 3 L / min. Samples were taken every hour for gas chromatography analysis of the product content. The weights of the feed material and the output were also recorded to calculate the yield.

[0073] Example 4:

[0074] Hydrothermal treatment: 200g of pyridine catalyst A is loaded into a fluidized bed at 600℃. Air is introduced at 2L / min, and pure water is introduced into the fluidized bed via a preheater at 6mL / min. Timing begins when water vapor enters the fluidized bed and contacts the catalyst. After 60 hours of water supply, the water supply is stopped, and the catalyst is removed after 10 minutes of blowing.

[0075] Reaction: The dismantled pyridine catalyst, which had undergone hydrothermal treatment for 60 hours, was loaded into a fluidized bed reactor at 450℃. The feed material was a mixture of methyl acetaldehyde, with a feed rate of 2 mL / min and an ammonia gas flow rate of 3 L / min. Samples were taken every hour for gas chromatography analysis of the product content. The weights of the feed material and the output material were also recorded to calculate the yield.

[0076] Example 5:

[0077] Hydrothermal treatment: 200g of pyridine catalyst A is loaded into a fluidized bed at 600℃. Air is introduced at 2L / min, and pure water is introduced into the fluidized bed via a preheater at 8mL / min. Timing begins when water vapor enters the fluidized bed and contacts the catalyst. After 10 hours of water supply, the water supply is stopped, and after 10 minutes of blowing, the air supply is stopped and the catalyst is removed.

[0078] Reaction: The dismantled pyridine catalyst, which had undergone hydrothermal treatment for 10 hours, was loaded into a fluidized bed reactor at 450℃. The feed material was a mixture of methyl acetaldehyde, with a feed rate of 2 mL / min and an ammonia gas flow rate of 3 L / min. Samples were taken every hour for gas chromatography analysis of the product content. The weights of the feed material and the output were also recorded to calculate the yield.

[0079] Example 6:

[0080] Hydrothermal treatment: 200g of pyridine catalyst A is loaded into a fluidized bed at 600℃. Air is introduced at 2L / min, and pure water is introduced into the fluidized bed via a preheater at 8mL / min. Timing begins when water vapor enters the fluidized bed and contacts the catalyst. After 20 hours of water supply, the water supply is stopped, and the catalyst is removed after 10 minutes of blowing.

[0081] Reaction: The dismantled pyridine catalyst, which had undergone hydrothermal treatment for 20 hours, was loaded into a fluidized bed reactor at 450℃. The feed material was a mixture of methyl acetaldehyde, with a feed rate of 2 mL / min and an ammonia gas flow rate of 3 L / min. Samples were taken every hour for gas chromatography analysis of the product content. The weights of the feed material and the output material were also recorded to calculate the yield.

[0082] Example 7:

[0083] Hydrothermal treatment: 200g of pyridine catalyst A is loaded into a fluidized bed at 600℃. Air is introduced at 2L / min, and pure water is introduced into the fluidized bed via a preheater at 8mL / min. Timing begins when water vapor enters the fluidized bed and contacts the catalyst. After 30 hours of water supply, the water supply is stopped, and after 10 minutes of blowing, the air supply is stopped and the catalyst is removed.

[0084] Reaction: The dismantled pyridine catalyst, which had undergone hydrothermal treatment for 30 hours, was loaded into a fluidized bed reactor at 450℃. The feed material was a mixture of methyl acetaldehyde, with a feed rate of 2 mL / min and an ammonia gas flow rate of 3 L / min. Samples were taken every hour for gas chromatography analysis of the product content. The weights of the feed material and the output were also recorded to calculate the yield.

[0085] Example 8:

[0086] Hydrothermal treatment: 200g of pyridine catalyst A is loaded into a fluidized bed at 600℃. Air is introduced at 2L / min, and pure water is introduced into the fluidized bed via a preheater at 8mL / min. Timing begins when water vapor enters the fluidized bed and contacts the catalyst. After 60 hours of water supply, the water supply is stopped, and the catalyst is removed after 10 minutes of blowing.

[0087] Reaction: The dismantled pyridine catalyst, which had undergone hydrothermal treatment for 60 hours, was loaded into a fluidized bed reactor at 450℃. The feed material was a mixture of methyl acetaldehyde, with a feed rate of 2 mL / min and an ammonia gas flow rate of 3 L / min. Samples were taken every hour for gas chromatography analysis of the product content. The weights of the feed material and the output material were also recorded to calculate the yield.

[0088] Example 9:

[0089] Hydrothermal treatment: 200g of pyridine catalyst A is loaded into an 800℃ fluidized bed. Air is introduced at a rate of 2L / min, and pure water is introduced into the fluidized bed via a preheater at a rate of 8mL / min. Timing begins when steam enters the fluidized bed and contacts the catalyst. After 10 hours of water supply, the water supply is stopped, and after 10 minutes of blowing, the air supply is stopped and the catalyst is removed.

[0090] Reaction: The dismantled pyridine catalyst, which had undergone hydrothermal treatment for 10 hours, was loaded into a fluidized bed reactor at 450℃. The feed material was a mixture of methyl acetaldehyde, with a feed rate of 2 mL / min and an ammonia gas flow rate of 3 L / min. Samples were taken every hour for gas chromatography analysis of the product content. The weights of the feed material and the output were also recorded to calculate the yield.

[0091] Example 10:

[0092] Hydrothermal treatment: 200g of pyridine catalyst A is loaded into an 800℃ fluidized bed. Air is introduced at a rate of 2L / min, and pure water is introduced into the fluidized bed via a preheater at a rate of 8mL / min. Timing begins when steam enters the fluidized bed and contacts the catalyst. After 20 hours of water supply, the water supply is stopped, and the catalyst is removed after 10 minutes of blowing.

[0093] Reaction: The dismantled pyridine catalyst, which had undergone hydrothermal treatment for 20 hours, was loaded into a fluidized bed reactor at 450℃. The feed material was a mixture of methyl acetaldehyde, with a feed rate of 2 mL / min and an ammonia gas flow rate of 3 L / min. Samples were taken every hour for gas chromatography analysis of the product content. The weights of the feed material and the output material were also recorded to calculate the yield.

[0094] Example 11:

[0095] Hydrothermal treatment: 200g of pyridine catalyst A is loaded into an 800℃ fluidized bed. Air is introduced at a rate of 2L / min, and pure water is introduced into the fluidized bed via a preheater at a rate of 8mL / min. Timing begins when steam enters the fluidized bed and contacts the catalyst. After 30 hours of water supply, the water supply is stopped, and the catalyst is removed after 10 minutes of blowing.

[0096] Reaction: The dismantled pyridine catalyst, which had undergone hydrothermal treatment for 30 hours, was loaded into a fluidized bed reactor at 450℃. The feed material was a mixture of methyl acetaldehyde, with a feed rate of 2 mL / min and an ammonia gas flow rate of 3 L / min. Samples were taken every hour for gas chromatography analysis of the product content. The weights of the feed material and the output were also recorded to calculate the yield.

[0097] Example 12:

[0098] Hydrothermal treatment: 200g of pyridine catalyst A is loaded into an 800℃ fluidized bed. Air is introduced at a rate of 2L / min, and pure water is introduced into the fluidized bed via a preheater at a rate of 8mL / min. Timing begins when steam enters the fluidized bed and contacts the catalyst. After 60 hours of water supply, the water supply is stopped, and the catalyst is removed after 10 minutes of blowing.

[0099] Reaction: The dismantled pyridine catalyst, which had undergone hydrothermal treatment for 60 hours, was loaded into a fluidized bed reactor at 450℃. The feed material was a mixture of methyl acetaldehyde, with a feed rate of 2 mL / min and an ammonia gas flow rate of 3 L / min. Samples were taken every hour for gas chromatography analysis of the product content. The weights of the feed material and the output material were also recorded to calculate the yield.

[0100] Example 13:

[0101] Hydrothermal treatment: 200g of pyridine catalyst B is loaded into a fluidized bed at 600℃. Air is introduced at 2L / min, and pure water is introduced into the fluidized bed via a preheater at 6mL / min. Timing begins when water vapor enters the fluidized bed and contacts the catalyst. After 10 hours of water supply, the water supply is stopped, and after 10 minutes of blowing, the air supply is stopped and the catalyst is removed.

[0102] Reaction: The dismantled pyridine catalyst, which had undergone hydrothermal treatment for 10 hours, was loaded into a fluidized bed reactor at 450℃. The feed material was a mixture of methyl acetaldehyde, with a feed rate of 2 mL / min and an ammonia gas flow rate of 3 L / min. Samples were taken every hour for gas chromatography analysis of the product content. The weights of the feed material and the output were also recorded to calculate the yield.

[0103] Example 14:

[0104] Hydrothermal treatment: 200g of pyridine catalyst B is loaded into a fluidized bed at 600℃. Air is introduced at 2L / min, and pure water is introduced into the fluidized bed via a preheater at 6mL / min. Timing begins when water vapor enters the fluidized bed and contacts the catalyst. After 20 hours of water supply, the water supply is stopped, and the catalyst is removed after 10 minutes of blowing.

[0105] Reaction: The dismantled pyridine catalyst, which had undergone hydrothermal treatment for 20 hours, was loaded into a fluidized bed reactor at 450℃. The feed material was a mixture of methyl acetaldehyde, with a feed rate of 2 mL / min and an ammonia gas flow rate of 3 L / min. Samples were taken every hour for gas chromatography analysis of the product content. The weights of the feed material and the output material were also recorded to calculate the yield.

[0106] Example 15:

[0107] Hydrothermal treatment: 200g of pyridine catalyst B is loaded into a fluidized bed at 600℃. Air is introduced at 2L / min, and pure water is introduced into the fluidized bed via a preheater at 6mL / min. Timing begins when water vapor enters the fluidized bed and contacts the catalyst. After 30 hours of water supply, the water supply is stopped, and the catalyst is removed after 10 minutes of blowing.

[0108] Reaction: The dismantled pyridine catalyst, which had undergone hydrothermal treatment for 30 hours, was loaded into a fluidized bed reactor at 450℃. The feed material was a mixture of methyl acetaldehyde, with a feed rate of 2 mL / min and an ammonia gas flow rate of 3 L / min. Samples were taken every hour for gas chromatography analysis of the product content. The weights of the feed material and the output were also recorded to calculate the yield.

[0109] Example 16:

[0110] Hydrothermal treatment: 200g of pyridine catalyst B is loaded into a fluidized bed at 600℃. Air is introduced at 2L / min, and pure water is introduced into the fluidized bed via a preheater at 6mL / min. Timing begins when water vapor enters the fluidized bed and contacts the catalyst. After 60 hours of water supply, the water supply is stopped, and the catalyst is removed after 10 minutes of blowing.

[0111] Reaction: The dismantled pyridine catalyst, which had undergone hydrothermal treatment for 60 hours, was loaded into a fluidized bed reactor at 450℃. The feed material was a mixture of methyl acetaldehyde, with a feed rate of 2 mL / min and an ammonia gas flow rate of 3 L / min. Samples were taken every hour for gas chromatography analysis of the product content. The weights of the feed material and the output material were also recorded to calculate the yield.

[0112] Example 17:

[0113] Hydrothermal treatment: 200g of pyridine catalyst B is loaded into a fluidized bed at 600℃. Air is introduced at 2L / min, and pure water is introduced into the fluidized bed via a preheater at 8mL / min. Timing begins when water vapor enters the fluidized bed and contacts the catalyst. After 10 hours of water supply, the water supply is stopped, and after 10 minutes of blowing, the air supply is stopped and the catalyst is removed.

[0114] Reaction: The dismantled pyridine catalyst, which had undergone hydrothermal treatment for 10 hours, was loaded into a fluidized bed reactor at 450℃. The feed material was a mixture of methyl acetaldehyde, with a feed rate of 2 mL / min and an ammonia gas flow rate of 3 L / min. Samples were taken every hour for gas chromatography analysis of the product content. The weights of the feed material and the output were also recorded to calculate the yield.

[0115] Example 18:

[0116] Hydrothermal treatment: 200g of pyridine catalyst B is loaded into a fluidized bed at 600℃. Air is introduced at 2L / min, and pure water is introduced into the fluidized bed via a preheater at 8mL / min. Timing begins when water vapor enters the fluidized bed and contacts the catalyst. After 20 hours of water supply, the water supply is stopped, and the catalyst is removed after 10 minutes of blowing.

[0117] Reaction: The dismantled pyridine catalyst, which had undergone hydrothermal treatment for 20 hours, was loaded into a fluidized bed reactor at 450℃. The feed material was a mixture of methyl acetaldehyde, with a feed rate of 2 mL / min and an ammonia gas flow rate of 3 L / min. Samples were taken every hour for gas chromatography analysis of the product content. The weights of the feed material and the output material were also recorded to calculate the yield.

[0118] Example 19:

[0119] Hydrothermal treatment: 200g of pyridine catalyst B is loaded into a fluidized bed at 600℃. Air is introduced at 2L / min, and pure water is introduced into the fluidized bed via a preheater at 8mL / min. Timing begins when water vapor enters the fluidized bed and contacts the catalyst. After 30 hours of water supply, the water supply is stopped, and the catalyst is removed after 10 minutes of blowing.

[0120] Reaction: The dismantled pyridine catalyst, which had undergone hydrothermal treatment for 30 hours, was loaded into a fluidized bed reactor at 450℃. The feed material was a mixture of methyl acetaldehyde, with a feed rate of 2 mL / min and an ammonia gas flow rate of 3 L / min. Samples were taken every hour for gas chromatography analysis of the product content. The weights of the feed material and the output were also recorded to calculate the yield.

[0121] Example 20:

[0122] Hydrothermal treatment: 200g of pyridine catalyst B is loaded into a fluidized bed at 600℃. Air is introduced at 2L / min, and pure water is introduced into the fluidized bed via a preheater at 8mL / min. Timing begins when water vapor enters the fluidized bed and contacts the catalyst. After 60 hours of water supply, the water supply is stopped, and the catalyst is removed after 10 minutes of blowing.

[0123] Reaction: The dismantled pyridine catalyst, which had undergone hydrothermal treatment for 60 hours, was loaded into a fluidized bed reactor at 450℃. The feed material was a mixture of methyl acetaldehyde, with a feed rate of 2 mL / min and an ammonia gas flow rate of 3 L / min. Samples were taken every hour for gas chromatography analysis of the product content. The weights of the feed material and the output material were also recorded to calculate the yield.

[0124] Example 21:

[0125] Hydrothermal treatment: 200g of pyridine catalyst B is loaded into an 800℃ fluidized bed. Air is introduced at a rate of 2L / min, and pure water is introduced into the fluidized bed via a preheater at a rate of 8mL / min. Timing begins when steam enters the fluidized bed and contacts the catalyst. After 10 hours of water supply, the water supply is stopped, and after 10 minutes of blowing, the air supply is stopped and the catalyst is removed.

[0126] Reaction: The dismantled pyridine catalyst, which had undergone hydrothermal treatment for 10 hours, was loaded into a fluidized bed reactor at 450℃. The feed material was a mixture of methyl acetaldehyde, with a feed rate of 2 mL / min and an ammonia gas flow rate of 3 L / min. Samples were taken every hour for gas chromatography analysis of the product content. The weights of the feed material and the output were also recorded to calculate the yield.

[0127] Example 22:

[0128] Hydrothermal treatment: 200g of pyridine catalyst B is loaded into an 800℃ fluidized bed, with air introduced at 2L / min. Pure water is introduced into the fluidized bed via a preheater at 8mL / min. Timing begins when steam enters the fluidized bed and contacts the catalyst. After 20 hours of water supply, the water supply is stopped, and the catalyst is removed after 10 minutes of blowing.

[0129] Reaction: The dismantled pyridine catalyst, which had undergone hydrothermal treatment for 20 hours, was loaded into a fluidized bed reactor at 450℃. The feed material was a mixture of methyl acetaldehyde, with a feed rate of 2 mL / min and an ammonia gas flow rate of 3 L / min. Samples were taken every hour for gas chromatography analysis of the product content. The weights of the feed material and the output material were also recorded to calculate the yield.

[0130] Example 23:

[0131] Hydrothermal treatment: 200g of pyridine catalyst B is loaded into an 800℃ fluidized bed, with air introduced at 2L / min. Pure water is fed into the fluidized bed via a preheater at 8mL / min. Timing begins when steam enters the fluidized bed and contacts the catalyst. After 30 hours of water supply, the water supply is stopped, and the catalyst is removed after 10 minutes of blowing.

[0132] Reaction: The dismantled pyridine catalyst, which had undergone hydrothermal treatment for 30 hours, was loaded into a fluidized bed reactor at 450℃. The feed material was a mixture of methyl acetaldehyde, with a feed rate of 2 mL / min and an ammonia gas flow rate of 3 L / min. Samples were taken every hour for gas chromatography analysis of the product content. The weights of the feed material and the output were also recorded to calculate the yield.

[0133] Example 24:

[0134] Hydrothermal treatment: 200g of pyridine catalyst B is loaded into an 800℃ fluidized bed, with air introduced at 2L / min. Pure water is fed into the fluidized bed via a preheater at 8mL / min. Timing begins when steam enters the fluidized bed and contacts the catalyst. After 60 hours of water supply, the water supply is stopped, and the catalyst is removed after 10 minutes of blowing.

[0135] Reaction: The dismantled pyridine catalyst, which had undergone hydrothermal treatment for 60 hours, was loaded into a fluidized bed reactor at 450℃. The feed material was a mixture of methyl acetaldehyde, with a feed rate of 2 mL / min and an ammonia gas flow rate of 3 L / min. Samples were taken every hour for gas chromatography analysis of the product content. The weights of the feed material and the output material were also recorded to calculate the yield.

[0136] Comparative Example 1:

[0137] 200g of pyridine catalyst A was packed into a fluidized bed reactor at 450℃. The raw material was a mixture of methyl acetaldehyde, with a feed rate of 2mL / min and an ammonia gas flow rate of 3L / min. Samples were taken every hour for gas chromatography analysis of the product content. The weights of the raw materials and the output were also recorded to calculate the yield.

[0138] Comparative Example 2:

[0139] 200g of pyridine catalyst B was packed into a fluidized bed reactor at 450℃. The raw material was a mixture of methyl acetaldehyde, with a feed rate of 2mL / min and an ammonia gas flow rate of 3L / min. Samples were taken every hour for gas chromatography analysis of the product content. The weights of the raw materials and the output were also recorded to calculate the yield.

[0140] Catalyst A and Catalyst B are molecular sieves synthesized in small-scale trials from different manufacturers.

[0141] The table below shows the yields of the above embodiments and comparative examples after testing.

[0142]

[0143]

[0144] As demonstrated in the examples, the longer the water treatment time, the higher the hydrothermal treatment temperature, and the larger the water flow rate, the more severe the damage to the catalyst's stability. Comparing results at the same temperature and water flow rate, the catalyst yield decreases with prolonged water treatment time, especially after 30 hours or more.

[0145] The yields of catalysts A and B without water treatment in the synthesis of pyridine bases from formaldehyde and acetaldehyde were significantly higher than those of catalysts A and B after water treatment under different conditions, as shown in Comparative Examples 1 and 2. Conventional methods require repeated regeneration of catalysts to screen for stable catalysts, testing the extent of performance degradation. Here, we continuously regenerated catalysts A and B 20 times, observed their stability, and compared it with hydrothermal stability.

[0146] Example 25

[0147] Pyridine catalyst A was charged into a fluidized bed reactor at 450℃. The feedstock was a mixture of methyl acetaldehyde, with a feed rate of 2 mL / min and an ammonia gas flow rate of 3 L / min. Samples were taken hourly for gas chromatography analysis of the product content, and the feed and product weights were recorded to calculate the yield. After one regeneration, catalyst A was placed in a muffle furnace at 550℃ for regeneration. The yields of catalyst A after 1, 5, 10, 15, and 20 regenerations were calculated.

[0148] Example 26

[0149] Pyridine catalyst B was loaded into a fluidized bed reactor at 450℃. The feedstock was a mixture of methyl acetaldehyde, with a feed rate of 2 mL / min and an ammonia gas flow rate of 3 L / min. Samples were taken hourly for gas chromatography analysis of the product content, and the feed and product weights were recorded to calculate the yield. After one regeneration, catalyst A was placed in a muffle furnace at 550℃ for regeneration. The yield of catalyst B was calculated after 1, 5, 10, 15, and 20 regenerations.

[0150] Table 2. Yield data for repeated regeneration of catalyst A and catalyst B.

[0151]

[0152] Comparing the hydrothermal regeneration stability and repeated regeneration of catalysts, it can be seen that the hydrothermal stability test method can significantly shorten the testing time, which is beneficial for rapid catalyst screening. If the yield of a pyridine catalyst does not decrease or decreases only slightly after 30 hours of hydrothermal treatment, it indicates that the catalyst has good hydrothermal stability. If the yield decreases significantly after less than 30 hours of hydrothermal treatment, the catalyst has poor hydrothermal stability. If the yield of a pyridine catalyst does not decrease significantly or does not decrease at all after 60 hours of hydrothermal treatment, it indicates that the catalyst has excellent hydrothermal stability, and this can be used as a standard for catalyst screening.

[0153] Although the invention has been illustrated and described with reference to specific embodiments, it should be understood that many other changes and modifications can be made without departing from the spirit and scope of the invention. Therefore, it is intended that all such changes and modifications falling within the scope of the invention be included in the appended claims.

Claims

1. A method for screening pyridine catalysts, characterized in that, include: The following methods were used to test the stability of pyridine catalysts: S1. Place the pyridine catalyst in a fluidized bed reactor; S2: Water is introduced by a feed pump. After vaporization, the water comes into contact with the pyridine catalyst. The water treatment time is 30h and 60h, respectively, with the contact time between water vapor and the pyridine catalyst as the starting point. Then the pyridine catalyst after hydrothermal treatment is removed. The flow rate of the water introduced in S2 is 2-8mL / min. S3. The hydrothermally treated pyridine catalyst is placed in another fluidized bed reactor for reaction. The feed consists of formaldehyde and acetaldehyde, and ammonia gas is introduced simultaneously. The feed flow rate is 2-10 mL / min, and the ammonia gas flow rate is 1-5 L / min. S4. Take a sample at a set time interval, record the weight of the feed and discharge, and calculate the yield; In step S1, after placing the pyridine catalyst in the fluidized bed reactor, the step of introducing air or nitrogen at a rate of 1-5 L / min is also included. If the yield decreases more than the first preset range after testing with a water treatment time of 30 hours, the pyridine catalyst is determined to be a substandard catalyst. If the yield does not decrease or decreases within the first preset range after testing with a water treatment time of 30 hours, and the yield decreases beyond the second preset range after testing with a water treatment time of 60 hours, then the pyridine catalyst is determined to be a qualified catalyst. If, after testing for 60 hours of water treatment, the yield decreases within the second preset range, then the pyridine catalyst is determined to be a high-quality catalyst.

2. The pyridine catalyst screening method according to claim 1, characterized in that, The temperature inside the fluidized bed reactor in S1 is 500-800℃.

3. The pyridine catalyst screening method according to claim 1, characterized in that, The temperature inside the other fluidized bed reactor in S3 is 350-500℃.

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