Application of titanium silicalite molecular sieve catalyst in ammoximation reaction
By activating and modifying the titanium silicon molecular sieve catalyst, the problem of small number of catalytic active sites is solved, the catalytic capacity of the amoximetization reaction and the purity of the product are improved, and a more efficient and economical production process is achieved.
Patent Information
- Application Number
- CN202510116846.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-24
- Publication Date
- 2025-05-13
AI Technical Summary
The number of catalytic active sites of titanium silicon molecular sieve catalysts in the amoxixilation reaction is small, which affects its catalytic ability.
By performing activation modification of gradient heating calcination, equal volume impregnation, drying and secondary calcination on the titanium silicon molecular sieve catalyst, its crystal structure and catalytic activity sites are optimized, and the activity and selectivity of the catalyst are enhanced.
The catalytic capacity of the titanium silicon molecular sieve catalyst is improved, the selectivity and yield of the amoximetization reaction is enhanced, the occurrence of side reactions is reduced, and the purity and production efficiency of the product are improved.
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Abstract
Description
Technical Field
[0001] The invention relates to the technical field of chemical synthesis, in particular to the application of a titanium silicon molecular sieve catalyst in an ammoximation reaction. Background Art
[0002] Ammoximation reaction plays an important role in the field of organic synthesis. As a key product, 2,5-furandicarboxaldehyde oxime has many limitations in its traditional synthesis process. On the one hand, conventional catalysts have poor activity and selectivity, resulting in low reaction efficiency, many side reactions, and difficulty in improving product purity and yield. On the other hand, reaction conditions are difficult to control, and high requirements are placed on reaction equipment, which increases production costs. Titanium silicate molecular sieve catalysts, due to their unique crystal structure and catalytic active sites, have a regular pore structure and can provide specific diffusion paths for reactant molecules, which is beneficial to improving reaction selectivity.
[0003] However, in the existing technology, the number of catalytically active sites in the titanium silicate molecular sieve catalyst is relatively small, resulting in limited catalytic ability for the ammoximation reaction. Summary of the invention
[0004] In view of the deficiencies of the prior art, the present invention provides an application of a titanium silicate molecular sieve catalyst in an ammoximation reaction to solve the problem that the number of catalytically active sites of the titanium silicate molecular sieve catalyst is relatively small, thus affecting the catalytic ability.
[0005] To achieve the above object, the present invention is implemented by the following technical scheme: the use of titanium silicon molecular sieve catalyst in ammoximation reaction comprises the following steps:
[0006] S1. Raw material preparation and pretreatment: prepare 2,5-diformylfuran, liquid ammonia or ammonia gas, hydrogen peroxide solution and buffer solution, and select titanium silicalite catalyst for activation treatment;
[0007] S2. Construction of reaction system: In a reaction vessel equipped with stirring, temperature control and gas introduction devices, a buffer solution is first added, 2,5-diformylfuran and titanium silicon molecular sieve catalyst are added in sequence under stirring, and liquid ammonia or ammonia gas is then introduced to form a uniform reaction system;
[0008] S3, initiation of oxidation reaction: adding hydrogen peroxide solution dropwise, activating hydrogen peroxide through titanium silicon molecular sieve catalyst to generate active oxygen species, and the active oxygen species then oxidize 2,5-diformylfuran;
[0009] S4, ammonia oximation reaction is carried out: ammonia molecules in ammonia gas attack the carbon of oxidized 2,5-diformylfuranaldehyde nucleophilically to generate 2,5-furandicarboxaldehyde oxime, and stirring and temperature control are continued during the reaction, and 2,5-diformylfuran reactant substrate is added as needed;
[0010] S5. Product separation and purification: The catalyst is separated by filtration and centrifugation, the solvent and unreacted raw materials are removed by distillation, and then a high-purity 2,5-furandicarboxaldehyde oxime product is obtained by recrystallization.
[0011] Preferably, the S1 specifically comprises the following steps:
[0012] S101. Performing purity test on 2,5-diformylfuran by high performance liquid chromatography, requiring the purity to reach more than 99%;
[0013] S102, placing the titanium silicon molecular sieve catalyst into a muffle furnace, gradually increasing the temperature to 500°C-600°C, and continuing roasting for 3h-5h;
[0014] S103, cooling the calcined titanium silicon molecular sieve catalyst to room temperature, and immersing it in a manganese nitrate solution for 12 hours to 20 hours by an equal volume impregnation method;
[0015] S104, drying the titanium silicon molecular sieve catalyst in an oven at 80°C-100°C for 12 hours to remove moisture, and then placing it in a muffle furnace for secondary calcination.
[0016] Preferably, the S2 specifically includes the following steps:
[0017] S201, pouring the buffer solution into the reaction container and stirring, setting the stirring speed to 50-100 rpm, so that the buffer solution forms a flowing state in the reaction container;
[0018] S202, gradually adding 2,5-diformylfuran and gradually increasing the stirring speed to 100-200 rpm to mix it with the buffer solution;
[0019] S203, adding the titanium silicon molecular sieve catalyst to the reaction container in small batches, and after each batch is added, wait for 2 to 4 minutes before adding the next batch, and adjust the stirring speed to 200-300 rpm to form a stable suspension;
[0020] S204, introducing ammonia gas into the reaction container through the gas introduction device at a rate of 1-2 bubbles per second, and maintaining a stirring speed of 200-300 rpm.
[0021] Preferably, the buffer in S2 is made of sodium dihydrogen phosphate and disodium hydrogen phosphate, and is used to adjust the pH buffer range in the reaction container to 5.8-8.0.
[0022] Preferably, S301, controlling the temperature of the reaction system at 20-60° C. by using the temperature control of the reaction container;
[0023] S302, adding hydrogen peroxide solution dropwise, and the added volume is 0.5% to 1% of the total volume of the reaction system per minute.
[0024] Preferably, the active oxygen species in S3 include hydroxyl radicals, peroxyhydroxyl radicals and singlet oxygen.
[0025] Preferably, the S4 specifically comprises the following steps:
[0026] S401, every 30 to 60 minutes, take out 5 to 10 ml of the reaction solution from the reaction system using a pipette and centrifuge to remove solid impurities of the catalyst;
[0027] S402, analyzing the concentrations of 2,5-diformylfuran, 2,5-furandicarbaldehyde oxime and intermediate products in the reaction solution by high performance liquid chromatography;
[0028] S403, when the concentration of 2,5-diformylfuran drops to 20% to 30% of the initial concentration, 2,5-diformylfuran reactant substrate is supplemented, and the concentration change of 2,5-furan dicarbaldehyde oxime measured twice is less than 5%, it is judged that the reaction is finished.
[0029] Preferably, the recrystallization solvent in S5 includes but is not limited to an acetone-water mixed solvent and a methanol-water mixed solvent.
[0030] The present invention provides the use of titanium silicon molecular sieve catalyst in ammoximation reaction. It has the following beneficial effects:
[0031] 1. The present invention activates and modifies the titanium silicon molecular sieve catalyst, first removes impurities and moisture after gradient temperature calcination, adjusts the crystal structure, exposes active sites to improve basic activity, and then cools and impregnates it in a manganese nitrate solution by an equal volume impregnation method, and then dries and calcines it twice to optimize the structural performance, enhance the catalyst stability and high selectivity.
[0032] 2. The present invention gradually adds 2,5-diformylfuran and catalysts in batches, accurately controls the speed of ammonia introduction, and during the reaction, controls the temperature and the dripping rate of the hydrogen peroxide solution to ensure a smooth and efficient reaction, monitors the concentration of the reaction solution, supplements the substrate according to the change in the concentration of key substances, determines the end point, and improves the effect of product yield and purity.
[0033] 3. The present invention separates the catalyst by centrifugation after filtration, which is convenient for recycling and reuse, reducing costs, and then uses distillation to remove the solvent and unreacted raw materials based on the difference in boiling points, preliminarily purifies the product, and finally recrystallizes it. By utilizing the difference in solubility of the product and impurities in the solvent at different temperatures, trace impurities are further removed to obtain high-purity 2,5-furandicarboxaldehyde oxime, thereby meeting strict product quality standards and improving the resource utilization and economic benefits of the production process. BRIEF DESCRIPTION OF THE DRAWINGS
[0034] Figure 1 The present invention is a flow chart of the application of the titanium silicon molecular sieve catalyst in the ammoximation reaction;
[0035] Figure 2 is a liquid phase chromatogram of 2,5-diformylfuran of the present invention;
[0036] Figure 3 It is the liquid phase chromatogram of 2,5-furandicarbaldehyde oxime of the present invention. DETAILED DESCRIPTION
[0037] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.
[0038] Please see attached Figure 1 - Attachment Figure 3 The embodiment of the present invention provides the use of a titanium silicon molecular sieve catalyst in an ammoximation reaction, comprising the following steps:
[0039] S1. Raw material preparation and pretreatment: prepare 2,5-diformylfuran, liquid ammonia or ammonia gas, hydrogen peroxide solution and buffer solution, and select titanium silicalite catalyst for activation treatment;
[0040] S2. Construction of reaction system: In a reaction vessel equipped with stirring, temperature control and gas introduction devices, a buffer solution is first added, 2,5-diformylfuran and titanium silicon molecular sieve catalyst are added in sequence under stirring, and liquid ammonia or ammonia gas is then introduced to form a uniform reaction system;
[0041] S3, initiation of oxidation reaction: adding hydrogen peroxide solution dropwise, activating hydrogen peroxide through titanium silicon molecular sieve catalyst to generate active oxygen species, and the active oxygen species then oxidize 2,5-diformylfuran;
[0042] S4, ammonia oximation reaction is carried out: ammonia molecules in ammonia gas attack the carbon of oxidized 2,5-diformylfuranaldehyde nucleophilically to generate 2,5-furandicarboxaldehyde oxime, and stirring and temperature control are continued during the reaction, and 2,5-diformylfuran reactant substrate is added as needed;
[0043] S5. Product separation and purification: The catalyst is separated by filtration and centrifugation, the solvent and unreacted raw materials are removed by distillation, and then a high-purity 2,5-furandicarboxaldehyde oxime product is obtained by recrystallization.
[0044] Specifically, in S1, high-purity 2,5-diformylfuran, liquid ammonia or ammonia gas, hydrogen peroxide solution and buffer solution are prepared to provide pure reactants for subsequent reactions, ensuring that the reaction can proceed smoothly, and the activation treatment of the titanium silicon molecular sieve catalyst can improve the activity and selectivity of the catalyst, so that it can play a better catalytic role in subsequent reactions, lay a good material foundation for subsequent reactions, reduce problems such as low reaction efficiency and increased side reactions caused by raw material impurities or insufficient catalyst activity, and create conditions for the efficient and stable development of the entire reaction;
[0045] The buffer in S2 is used to maintain the stability of the pH of the reaction system, ensuring that the reaction is carried out in a suitable pH environment to avoid the influence of pH changes on the reaction process and catalyst activity. At the same time, the various substances are fully mixed by stirring to build a uniform and stable reaction system, which ensures the stability of the pH of the reaction system and is conducive to the orderly progress of the subsequent oxidation reaction and ammoximation reaction, thereby improving the consistency and repeatability of the reaction.
[0046] Hydrogen peroxide solution was added to S3 and activated with the help of titanium silicalite catalyst, which promoted the decomposition of hydrogen peroxide to produce active oxygen species. These active oxygen species have extremely strong oxidizing properties and can undergo oxidation reaction with 2,5-diformylfuran, change its molecular structure, introduce electron cloud distribution state on the aldehyde carbon that is beneficial to subsequent reactions, lay the foundation for nucleophilic attack of ammonia molecules, and then promote the entire reaction system to proceed in an orderly manner toward the direction of generating the target product 2,5-furandicarboxaldehyde oxime, successfully triggering subsequent key reactions;
[0047] The ammonia molecules in the ammonia gas in S4, with their nucleophilicity, initiate a nucleophilic attack on the oxidized 2,5-diformylfuran aldehyde carbon to generate the target product 2,5-furandicarboxaldehyde oxime. Continuous stirring promotes the full mixing of the ammonia molecules, the oxidized 2,5-diformylfuran and other substances in the reaction system, increases the probability of molecular collision, and accelerates the reaction process. Precise temperature control ensures that the reaction is carried out under suitable thermodynamic conditions to avoid abnormal reaction rate or increased side reactions due to temperature fluctuations. Afterwards, the 2,5-diformylfuran reactant substrate is supplemented as needed to ensure that the reactant concentration in the reaction system is maintained at a certain level, prevent the reaction from stagnating due to insufficient substrate, and effectively achieve the efficient generation of the target product 2,5-furandicarboxaldehyde oxime, and significantly improve the yield and purity of the product, ensuring the economic benefits and product quality of the entire reaction.
[0048] In S5, the titanium silicalite catalyst is first separated from the reaction mixture by filtering and centrifuging using a filter and centrifugal force for subsequent recycling and reuse, thereby reducing production costs. A distillation operation is then performed to vaporize and separate the solvent, unreacted raw materials, and products based on the difference in boiling points, thereby preliminarily removing most impurities. Finally, a recrystallization method is used to crystallize 2,5-furandicarboxaldehyde oxime using the change in solubility of the product at different temperatures in a specific solvent, thereby further removing residual trace impurities, thereby achieving the recycling of the titanium silicalite catalyst and successfully obtaining the target product 2,5-furandicarboxaldehyde oxime with high purity, thereby meeting the product quality standards and improving the resource utilization and economic benefits of the entire production process.
[0049] S1 specifically includes the following steps:
[0050] S101. Performing purity test on 2,5-diformylfuran by high performance liquid chromatography, requiring the purity to be above 99%, and selecting a hydrogen peroxide solution concentration of 30% to 50%;
[0051] S102, placing the titanium silicon molecular sieve catalyst into a muffle furnace, gradually increasing the temperature to 500°C-600°C, and continuing roasting for 3h-5h;
[0052] S103, cooling the calcined titanium silicon molecular sieve catalyst to room temperature, and immersing it in a manganese nitrate solution for 12 hours to 20 hours by an equal volume impregnation method;
[0053] S104, drying the titanium silicon molecular sieve catalyst in an oven at 80°C-100°C for 12 hours to remove moisture, and then placing it in a muffle furnace for secondary calcination.
[0054] Specifically, in S101, the purity of 2,5-diformylfuran is tested by high performance liquid chromatography to control the quality of the key raw material, so as to avoid insufficient purity of the raw material, which may lead to an increase in side reactions and affect the product quality and reaction rate. A 30% to 50% concentration of hydrogen peroxide solution is selected, which can stably decompose and produce active oxygen species under the action of titanium silicon molecular sieve catalyst, provide sufficient oxidant for the oxidation reaction, ensure the efficiency and stability of subsequent reactions, and improve the reliability and repeatability of the entire reaction process.
[0055] In S102, the titanium silicon molecular sieve catalyst is placed in a muffle furnace and continuously calcined by gradient heating, which can remove impurities and moisture adsorbed on the catalyst surface, adjust the crystal structure of the catalyst, and enhance its lattice stability. At the same time, high-temperature calcination can fully expose the active sites on the catalyst surface, improve the activity and catalytic performance of the catalyst, and provide strong catalytic support for the smooth progress of the entire reaction process, ensuring that subsequent reactions can be carried out under ideal catalytic conditions.
[0056] After the calcined titanium silicalite catalyst in S103 is cooled to room temperature, it is immersed in a manganese nitrate solution by an equal volume impregnation method, so that the manganese nitrate is evenly loaded on the surface and internal pores of the titanium silicalite catalyst. The manganese element, as an active component, produces a synergistic effect with the titanium silicalite, thereby improving the catalytic activity and selectivity of the catalyst. In the subsequent reaction, the catalyst loaded with manganese nitrate can more effectively activate the reactants, promote the oxidation reaction and the ammoximation reaction, improve the generation efficiency of the target product 2,5-furandicarboxaldehyde oxime, reduce the occurrence of side reactions, and optimize the entire reaction process;
[0057] Drying is performed in S104 to avoid interfering with the contact between the reactants and the active sites of the catalyst in the actual catalytic reaction. At the same time, secondary calcination can decompose the manganese nitrate supported on the catalyst into manganese oxide with catalytic activity and firmly attach it to the surface of the titanium silicon molecular sieve, further adjusting the crystal structure and surface properties of the catalyst and enhancing the interaction between the active components and the carrier.
[0058] S2 specifically includes the following steps:
[0059] S201, pouring the buffer solution into the reaction container and stirring, setting the stirring speed to 50-100 rpm, so that the buffer solution forms a flowing state in the reaction container;
[0060] S202, gradually adding 2,5-diformylfuran and gradually increasing the stirring speed to 100-200 rpm to mix it with the buffer solution;
[0061] S203, adding the titanium silicon molecular sieve catalyst to the reaction container in small batches, and after each batch is added, wait for 2 to 4 minutes before adding the next batch, and adjust the stirring speed to 200-300 rpm to form a stable suspension;
[0062] S204, introducing ammonia gas into the reaction container through the gas introduction device at a rate of 1-2 bubbles per second, and maintaining a stirring speed of 200-300 rpm.
[0063] Specifically, in S201, the buffer solution is poured into the reaction container and stirred at a low speed to create a stable reaction environment in advance to avoid adverse effects on the reaction process and catalyst activity due to pH fluctuations in the subsequent reaction. On the one hand, it helps to evenly disperse the reactants added later and create conditions for sufficient mixing of the substances. On the other hand, the stable flow state can promote mass transfer and heat transfer in the system, making the entire reaction environment more uniform.
[0064] In S202, 2,5-diformylfuran is gradually added and the stirring speed is increased to achieve full mixing of 2,5-diformylfuran and the buffer solution. The gradual addition can avoid excessive addition at one time, which leads to excessive local concentration and affects the mixing effect and the uniformity of subsequent reactions. Increasing the stirring speed can enhance the diffusion and collision between molecules, so that 2,5-diformylfuran is quickly and evenly dispersed in the buffer solution.
[0065] In S203, the titanium silicon molecular sieve catalyst is added in small batches to prevent the catalyst from agglomerating and to avoid excessively high or low local catalyst concentrations that affect the catalytic effect. A period of time is waited to allow the first added catalyst to have sufficient time to disperse evenly in the buffer solution and 2,5-diformylfuran mixture before adding the next batch. Increasing the stirring speed can further enhance the dispersion effect of the catalyst and increase its contact area with the reactants. Through this operation, a stable suspension is successfully formed, achieving uniform distribution of the catalyst in the reaction system, greatly improving the activity and utilization of the catalyst, ensuring that the subsequent oxidation reaction and ammoximation reaction can be carried out in an efficient catalytic environment, and effectively improving the reaction rate and selectivity of product formation.
[0066] In S204, ammonia is introduced into the reaction container at a rate of 1-2 bubbles per second, and high-speed stirring is maintained, so as to accurately control the amount of ammonia added and the mixing effect. Ammonia is introduced at a slower and more stable bubble rate to avoid a large influx of ammonia causing a sudden change in the pressure of the reaction system and excessive local concentration, thereby preventing the occurrence of side reactions. A high stirring speed is continuously maintained to allow the introduced ammonia to be quickly and evenly dispersed in the reaction system, thereby increasing the contact probability between ammonia and the oxidized 2,5-diformylfuran, and creating good conditions for the smooth progress of the ammonia oximation reaction.
[0067] S3 specifically includes the following steps:
[0068] S301, controlling the temperature of the reaction system at 20-60° C. by using the temperature control of the reaction container;
[0069] S302, adding hydrogen peroxide solution dropwise, and the added volume is 0.5% to 1% of the total volume of the reaction system per minute.
[0070] Specifically, in S301, the temperature of the reaction system is controlled at 20-60° C. by using the temperature control of the reaction container, so as to provide suitable thermodynamic conditions for the activation of hydrogen peroxide and the subsequent oxidation reaction of 2,5-diformylfuran, and ensure that the oxidation reaction is carried out in an efficient and stable environment, thus laying a good foundation for the subsequent ammoximation reaction to smoothly generate the target product 2,5-furandicarboxaldehyde oxime;
[0071] In S302, the hydrogen peroxide solution is added dropwise at a rate of 0.5% to 1% of the total volume of the reaction system per minute, which can avoid the instantaneous concentration of hydrogen peroxide being too high, causing the reaction to be too violent and difficult to control, and triggering side reactions. The hydrogen peroxide is continuously and stably decomposed to produce active oxygen species under the action of the titanium silicon molecular sieve catalyst, providing a continuous source of oxidant.
[0072] The reactive oxygen species in S3 include hydroxyl radicals, peroxyhydroxyl radicals and singlet oxygen.
[0073] Specifically, hydroxyl radicals, peroxyhydroxyl radicals and singlet oxygen have extremely high chemical activity and strong oxidizing properties, and can directly attack 2,5-diformylfuran molecules, oxidize 2,5-diformylfuran, and generate intermediates suitable for ammoximation reactions, thereby creating favorable conditions for the subsequent nucleophilic attack of ammonia molecules, and promoting the entire reaction to proceed smoothly in the direction of generating 2,5-furandicarboxaldehyde oxime, effectively improving the conversion rate of the reaction and the efficiency of generating the target product.
[0074] S4 specifically includes the following steps:
[0075] S401, every 30 to 60 minutes, take out 5 to 10 ml of the reaction solution from the reaction system using a pipette and centrifuge to remove solid impurities of the catalyst;
[0076] S402, analyzing the concentrations of 2,5-diformylfuran, 2,5-furandicarbaldehyde oxime and intermediate products in the reaction solution by high performance liquid chromatography;
[0077] S403, when the concentration of 2,5-diformylfuran drops to 20% to 30% of the initial concentration, 2,5-diformylfuran reactant substrate is supplemented, and the concentration change of 2,5-furan dicarbaldehyde oxime measured twice is less than 5%, it is judged that the reaction is finished.
[0078] Specifically, obtaining a clarified reaction liquid sample in S401 can prevent solid impurities such as catalysts from interfering with subsequent component analysis, provide a basis for accurately determining the concentration of each substance in the reaction liquid, provide a pure sample effect for subsequent analysis, and improve the accuracy of the analysis results;
[0079] In S402, high performance liquid chromatography is used to analyze the concentration of each substance, and the real-time concentration changes of 2,5-diformylfuran, 2,5-furandicarboxaldehyde oxime and intermediates in the reaction system are detected, so as to understand the progress and reaction rate of the reaction, clearly present the effect of the reaction dynamics, and enable operators to adjust the reaction conditions in time according to the actual situation;
[0080] In S403, when the concentration of 2,5-diformylfuran drops to 20% to 30% of the initial concentration, the substrate is supplemented to ensure that the reaction continues to have sufficient raw materials and maintain the efficient progress of the reaction. The end of the reaction is judged to be less than 5% when the concentration change of 2,5-furandicarboxaldehyde oxime is measured twice. The endpoint of the reaction can be accurately determined to avoid overreaction or insufficient reaction, thereby achieving the effect of accurately controlling the reaction process, improving the yield and quality of the target product, and reducing costs.
[0081] The recrystallization solvent in S5 includes but is not limited to an acetone-water mixed solvent and a methanol-water mixed solvent.
[0082] Specifically, acetone-water mixed solvent and methanol-water mixed solvent are selected as recrystallization solvents, the purpose of which is to use the difference in solubility of the target product 2,5-furandicarbaldehyde oxime and impurities in these mixed solvents as the temperature changes to achieve separation, thereby significantly improving the purity of the product, making it reach a higher quality standard, and meeting the strict requirements of subsequent applications on product purity.
[0083] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.
Claims
1. Application of titanium silicon molecular sieve catalyst in ammoximation reaction, characterized in that: The following steps are involved: S1. Raw material preparation and pretreatment: prepare 2,5-diformylfuran, liquid ammonia or ammonia gas, hydrogen peroxide solution and buffer solution, and select titanium silicalite catalyst for activation treatment; S2. Construction of reaction system: In a reaction vessel equipped with stirring, temperature control and gas introduction devices, a buffer solution is first added, 2,5-diformylfuran and titanium silicon molecular sieve catalyst are added in sequence under stirring, and liquid ammonia or ammonia gas is then introduced to form a uniform reaction system; S3, initiation of oxidation reaction: adding hydrogen peroxide solution dropwise, activating hydrogen peroxide through titanium silicon molecular sieve catalyst to generate active oxygen species, and the active oxygen species then oxidize 2,5-diformylfuran; S4, ammonia oximation reaction is carried out: ammonia molecules in ammonia gas attack the carbon of oxidized 2,5-diformylfuranaldehyde nucleophilically to generate 2,5-furandicarboxaldehyde oxime, and stirring and temperature control are continued during the reaction, and 2,5-diformylfuran reactant substrate is added as needed; S5. Product separation and purification: The catalyst is separated by filtration and centrifugation, the solvent and unreacted raw materials are removed by distillation, and then a high-purity 2,5-furandicarboxaldehyde oxime product is obtained by recrystallization.
2. The use of the titanium silicon molecular sieve catalyst in an ammoximation reaction according to claim 1, characterized in that: The S1 specifically includes the following steps: S101. Performing purity test on 2,5-diformylfuran by high performance liquid chromatography, requiring the purity to reach more than 99%; S102, placing the titanium silicon molecular sieve catalyst into a muffle furnace, gradually increasing the temperature to 500°C-600°C, and continuing roasting for 3h-5h; S103, cooling the calcined titanium silicon molecular sieve catalyst to room temperature, and immersing it in a manganese nitrate solution for 12 hours to 20 hours by an equal volume impregnation method; S104, drying the titanium silicon molecular sieve catalyst in an oven at 80°C-100°C for 12 hours to remove moisture, and then placing it in a muffle furnace for secondary calcination.
3. The use of the titanium silicon molecular sieve catalyst according to claim 1 in an ammoximation reaction, characterized in that: The S2 specifically includes the following steps: S201, pouring the buffer solution into the reaction container and stirring, setting the stirring speed to 50-100 rpm, so that the buffer solution forms a flowing state in the reaction container; S202, gradually adding 2,5-diformylfuran and gradually increasing the stirring speed to 100-200 rpm to mix it with the buffer solution; S203, adding the titanium silicon molecular sieve catalyst to the reaction container in small batches, and after each batch is added, wait for 2 to 4 minutes before adding the next batch, and adjust the stirring speed to 200-300 rpm to form a stable suspension; S204, introducing ammonia gas into the reaction container through the gas introduction device at a rate of 1-2 bubbles per second, and maintaining a stirring speed of 200-300 rpm.
4. The use of the titanium silicon molecular sieve catalyst in an ammoximation reaction according to claim 1, characterized in that: The buffer in S2 is made of sodium dihydrogen phosphate and disodium hydrogen phosphate, and is used to adjust the pH value in the reaction container to a buffer range of 5.8-8.
0.
5. The use of the titanium silicon molecular sieve catalyst in an ammoximation reaction according to claim 1, characterized in that: The S3 specifically includes the following steps: S301, controlling the temperature of the reaction system at 20-60° C. by using the temperature control of the reaction container; S302, adding hydrogen peroxide solution dropwise, and the added volume is 0.5% to 1% of the total volume of the reaction system per minute.
6. The use of the titanium silicon molecular sieve catalyst in an ammoximation reaction according to claim 1, characterized in that: The active oxygen species in S3 include hydroxyl radicals, peroxyhydroxyl radicals and singlet oxygen.
7. The use of the titanium silicon molecular sieve catalyst in an ammoximation reaction according to claim 1, characterized in that: The S4 specifically comprises the following steps: S401, every 30 to 60 minutes, take out 5 to 10 ml of the reaction solution from the reaction system using a pipette and centrifuge to remove solid impurities of the catalyst; S402, analyzing the concentrations of 2,5-diformylfuran, 2,5-furandicarbaldehyde oxime and intermediate products in the reaction solution by high performance liquid chromatography; S403, when the concentration of 2,5-diformylfuran drops to 20% to 30% of the initial concentration, 2,5-diformylfuran reactant substrate is supplemented, and the concentration change of 2,5-furan dicarbaldehyde oxime measured twice is less than 5%, it is judged that the reaction is finished.
8. The use of the titanium silicon molecular sieve catalyst in an ammoximation reaction according to claim 1, characterized in that: The recrystallization solvent in S5 includes but is not limited to an acetone-water mixed solvent and a methanol-water mixed solvent.