Preparation method of high-purity nicotinamide

Abstract

The invention provides a preparation method of high-purity nicotinamide, and belongs to the technical field of organic synthesis. Comprising the following steps: adding 3-aminomethylpyridine and a catalyst into a solvent, introducing ozone, heating and stirring for reaction, separating the catalyst by using a magnet, washing and drying, reusing, adding a purifying agent into liquid, carrying out heat preservation and stirring for reaction, filtering, washing, drying and reusing a solid purifying agent obtained by filtering, cooling filtrate, filtering, washing a solid, and drying to obtain the 3-aminomethylpyridine. The high-purity nicotinamide is prepared. The preparation method of the high-purity nicotinamide is simple, the nicotinamide product can be obtained in a high-yield and high-purity mode, the catalyst and the purifying agent can be repeatedly used, the production cost is reduced, the raw material source is wide, and the preparation method has wide application prospects.

Description

Technical Field

[0001] The invention relates to the technical field of organic synthesis, and in particular to a method for preparing high-purity nicotinamide. Background Art

[0002] Nicotinamide is a component of coenzyme I and coenzyme II, and is a coenzyme for many dehydrogenases. When it is deficient, it can affect the normal respiration and metabolism of cells and cause pellagra. In food processing, nicotinamide is used as a colorant together with vitamin C.

[0003] In industry, nicotinamide is produced by catalytic hydrolysis of 3-cyanopyridine. The catalysts mainly include acids, bases and several types of water-insoluble catalysts, such as nickel oxide, manganese dioxide, magnesium oxide, etc.; currently, nicotinic acid is mainly produced by enzymatic hydrolysis of 3-cyanopyridine. During the production process of nicotinamide, a small amount of nicotinamide is often produced. After concentration and granulation, nicotinic acid is produced, which affects the quality of nicotinamide and causes the quality inspection indicators such as nicotinamide product content, pH value, melting point, etc. to be unqualified. A lot of post-processing work is required to separate high-purity nicotinamide products.

[0004] The separation principle of nicotinamide ion exchange purification process is to use monovalent cation A + and B + Take the ion exchange reaction as an example (R is the resin matrix) ion exchange equation: A + +BR≒AR+B + There are great difficulties in the separation of nicotinamide. The traditional separation method is mainly intermittent, using cationic resin to convert nicotinamide in nicotinamide aqueous solution into nicotinic acid, and then adsorbing nicotinic acid through anionic resin to achieve the purpose of purifying nicotinamide. The continuous ion exchange system is used to separate nicotinamide aqueous solution, with high separation efficiency and stable process conditions. However, the industrial investment in equipment is relatively large and expensive. Summary of the invention

[0005] The purpose of the present invention is to provide a method for preparing high-purity nicotinamide. The preparation method is simple, and the nicotinamide product can be obtained with high yield and high purity. The catalyst and the purifying agent can be reused many times, thereby reducing the production cost. The raw material source is wide and the method has broad application prospects.

[0006] The technical solution of the present invention is achieved in this way: The invention provides a preparation method of high-purity nicotinamide, comprising the following steps: adding 3-aminomethylpyridine and a catalyst into a solvent, introducing ozone, heating and stirring for reaction, separating the catalyst with a magnet, washing and drying, and repeatedly reusing the solvent, adding a purifying agent into a liquid, keeping the temperature and stirring for reaction, filtering, washing the solid purifying agent obtained by filtration, drying, and repeatedly reusing the solid purifying agent, cooling the filtrate, filtering, washing the solid, and drying the solid to obtain the high-purity nicotinamide.

[0007] As a further improvement of the present invention, the mass ratio of the 3-aminomethylpyridine, the catalyst and the purifying agent is 10:2-3:0.5-1.5, the temperature of the heating and stirring reaction is 45-55°C, the time is 6-10h, the time of the heat preservation and stirring reaction is 1-2h, the temperature is cooled to 0-4°C, and the ventilation rate of the ozone is 8-15mL / min.

[0008] As a further improvement of the present invention, the preparation method of the catalyst is as follows: S1. Preparation of magnetic ferroferric oxide: ferric chloride and ferrous chloride are added to water, and under the protection of inert gas, ammonia is added, heated and stirred for reaction, centrifuged, washed, dried, and calcined to obtain magnetic ferroferric oxide; S2. Chemical vapor deposition of carbon nanotubes: heating magnetic ferroferric oxide while introducing a mixture of hydrogen and an inert gas, and when the temperature reaches a suitable temperature, adding a xylene solution of ferrocene dropwise, keeping the temperature for reaction, cooling while introducing only an inert gas, to obtain carbon nanotubes deposited with magnetic ferroferric oxide; S3. Modification: adding the carbon nanotube deposited magnetic ferroferric oxide to a Tris-HCl solution, adding dopamine hydrochloride, heating and stirring the reaction, separating with a magnet, washing, and drying to obtain a modified carbon nanotube deposited magnetic ferroferric oxide; S4. MnO 2 Deposition: Potassium permanganate is dissolved in water to obtain liquid A, and potassium permanganate solution is dissolved in water to obtain liquid B; the modified carbon nanotubes are deposited with magnetic ferroferric oxide, added to liquid B, stirred and mixed evenly, liquid A is added dropwise, stirred and reacted hydrothermally, separated by magnet, washed, and dried to obtain MnO 2 / Carbon nanotubes deposit magnetic ferroferric oxide; S5. Intercalation of lanthanum and cerium: Dissolve lanthanum salt and cerium salt in water and add MnO 2 / Carbon nanotubes are used to deposit magnetic ferrosoferric oxide, which is then heated and stirred for reaction, separated by a magnet, washed and dried to obtain a catalyst.

[0009] As a further improvement of the present invention, the mass ratio of ferric chloride, ferrous chloride and ammonia water in step S1 is 3.24:1.26:7-10, the temperature of the heating and stirring reaction is 80-90°C, the time is 3-5h, the temperature of the calcination is 500-600°C, and the time is 1-3h; the mass volume ratio of the xylene solution of magnetic ferrosinite and ferrocene in step S2 is 10g:5-8mL, the content of ferrocene in the xylene solution of ferrocene is 2-3wt%, the volume ratio of the hydrogen and inert gas mixture is 2-4:7-10, the suitable temperature is 800-900°C, and the insulation reaction time is 30-50min.

[0010] As a further improvement of the present invention, the mass ratio of the carbon nanotube deposited magnetic ferroferric oxide, dopamine hydrochloride and catalyst in step S3 is 12-18:3-5, the pH value of the Tris-HCl solution is 8.5-9.5, the temperature of the heating and stirring reaction is 45-55°C, and the time is 5-7h; the mass ratio of potassium permanganate, potassium manganate and modified carbon nanotube deposited magnetic ferroferric oxide in step S4 is 3-5:1.2-1.6:10, the temperature of the hydrothermal stirring reaction is 170-190°C, and the time is 20-24h; the lanthanum salt in step S5 is lanthanum nitrate or lanthanum chloride, the cerium salt is cerium nitrate or cerium chloride, and the lanthanum salt, cerium salt and MnO 2 The mass ratio of magnetic ferrosoferric oxide to carbon nanotube deposition is 1-2:0.5-1.5:35-45, and the temperature of the heating and stirring reaction is 40-50° C. and the time is 1-2 hours.

[0011] As a further improvement of the present invention, the preparation method of the purifying agent is as follows: T1. Preparation of modified molecular imprinted polymer: nicotinic acid, monomer, crosslinking agent and porogen are mixed, initiator is added under inert gas protection, polymerization reaction is heated, filtered, dried and ground to obtain polymer, which is then added to a Soxhlet extractor, eluted with washing liquid until nicotinic acid is undetectable, polymer particles are washed, sieved, 50-100 mesh particles are collected, and dried to obtain modified molecular imprinted polymer; T2. TiO 2 / ZnO loading: Tetrabutyl titanate and zinc acetate were added to ethanol, and citric acid aqueous solution was added dropwise, the pH value of the solution was adjusted, stirred for reaction, centrifuged, washed, dried, calcined, the product was added to water, and the modified molecular imprinting polymer was added, heated and stirred for reaction, and the loaded TiO 2 / ZnO molecular imprinted polymer; T3. Doping: Loading TiO 2 The molecular imprinting polymer of ZnO is added into the graphene oxide aqueous solution, and iron salt, cadmium salt and dithiol are added, the mixture is stirred and evenly mixed, and the mixture is spray-dried to prepare a purifying agent.

[0012] As a further improvement of the present invention, the mass ratio of nicotinic acid, monomer, cross-linking agent, porogen and initiator in step T1 is 3-5:15-20:0.1-0.2:0.5-1:0.01-0.015, the initiator is selected from at least one of sodium persulfate, potassium persulfate, ammonium persulfate and benzoyl peroxide, the monomer comprises a silane coupling agent with a double bond and butyl methacrylate, the mass ratio is 3-5:12-15, the silane coupling agent with a double bond is selected from at least one of KH570, A151 and A171, the porogen is acetone, the cross-linking agent is ethylene glycol dimethacrylate, the temperature of the heating polymerization reaction is 50-60°C, the time is 3-5h, and the washing liquid is a mixture of ethanol and acetic acid in a volume ratio of 100:3-5.

[0013] As a further improvement of the present invention, the mass ratio of tetrabutyl titanate, zinc acetate, citric acid and modified molecular imprinted polymer in step T2 is 3-5:2-4:1.2-1.5:10-12, the pH value of the adjusted solution is 9.5-10.5, the stirring reaction time is 2-4h, the temperature is 35-45°C, the calcination temperature is 450-550°C, the time is 2-4h, and the heating stirring reaction temperature is 40-50°C, and the time is 1-2h.

[0014] As a further improvement of the present invention, the TiO loaded in step T3 2 The mass ratio of the molecular imprinted polymer of ZnO, graphene oxide, iron salt, cadmium salt and dithiol is 12-15:3-5:0.1-0.2:0.12-0.15:1-2, the iron salt is iron nitrate or iron chloride, and the cadmium salt is cadmium nitrate.

[0015] As a further improvement of the present invention, the purity of the high-purity nicotinamide is >99.9%.

[0016] The present invention has the following beneficial effects: 1. The present invention prepares a novel catalyst, which takes magnetic ferroferric oxide as the core, and deposits a layered carbon nanotube structure on its surface by chemical vapor deposition, thereby increasing the specific surface area of ​​the catalyst. After subsequent intercalation of lanthanum and cerium ions, the loading amount of lanthanum and cerium ions is increased, and the catalytic active sites are greatly expanded. The surface is modified by polydopamine coating, so that the surface of its layered structure has "stickiness". The "stickiness" is given by the polyhydroxy and amino structures of polydopamine, which can adsorb manganate ions, thereby promoting its in-situ generation of MnO 2 , thus a catalyst with excellent oxidation catalytic performance is obtained, and lanthanum and cerium ions are used for intercalation. The intercalation of rare earth elements can improve the oxidation catalytic performance of the catalyst, and the two rare earth elements have a synergistic effect; 2. The present invention adopts the synergistic catalysis of the catalyst and ozone, which has the best catalytic effect and can make the reaction yield of nicotinamide reach more than 98%. However, the catalytic effect of a single catalyst and ozone catalysis is significantly reduced, which shows that the two have a synergistic effect; 3. The present invention also uses the prepared purifying agent to purify the prepared nicotinamide product system. In the preparation process of the molecular imprinting polymer, the silane coupling agent with double bonds and butyl methacrylate are used as raw materials. The polymer obtained by copolymerization has good affinity for inorganic substances, which is helpful for TiO 2 / ZnO loading, the product in the reaction system contains nicotinic acid byproducts, the purifying agent is mainly composed of molecular imprinting polymers, which can selectively adsorb nicotinic acid, and the loaded titanium dioxide and zinc oxide have good photocatalytic degradation effects, which can catalytically degrade the nicotinic acid loaded thereon, but the utilization rate of titanium dioxide for visible light is not high. In order to solve this problem, the present invention doped iron and cadmium ions, and loaded dithiol, the formed thiol bond complexed iron and cadmium ions, synergistically reduced the band gap width, significantly enhanced the visible light response, sensitized titanium dioxide, and the doping of S changed the hybridization of the O 2p orbital and the Ti 3d orbital, thereby improving the stability of the doping; 4. The method for preparing high-purity nicotinamide of the present invention is simple, and can obtain nicotinamide product with high yield and high purity, and the catalyst and the purifying agent can be reused many times, which reduces the production cost, has a wide source of raw materials, and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0018] Figure 1 This is the TEM image of the catalyst prepared in Preparation Example 1. DETAILED DESCRIPTION

[0019] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. 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.

[0020] Graphene oxide, thickness 0.6-1nm, specific surface area 1000-1200m 2 / g, flake diameter 1-3μm.

[0021] Preparation Example 1 The catalyst was prepared as follows: S1. Preparation of magnetic ferroferric oxide: 3.24 g ferric chloride and 1.26 g ferrous chloride were added to 150 mL water, and 7 g ammonia water was added under nitrogen protection. The mixture was heated to 80 ° C, stirred for 3 h, centrifuged, washed, dried, and calcined at 500 ° C for 1 h to obtain magnetic ferroferric oxide. S2. Chemical vapor deposition of carbon nanotubes: While heating 10g of magnetic ferroferric oxide, a mixture of hydrogen and nitrogen was introduced, wherein the volume ratio of the mixture of hydrogen and nitrogen was 2:7, and when the temperature was raised to 800°C, 5mL of a xylene solution of ferrocene was added dropwise, wherein the content of ferrocene in the xylene solution of ferrocene was 2wt%, and the reaction was kept at this temperature for 30min, and then cooled to room temperature, while only nitrogen was introduced to obtain magnetic ferroferric oxide deposited on carbon nanotubes; S3. Modification: 12 g of carbon nanotube-deposited magnetic ferroferric oxide was added to 200 mL of Tris-HCl solution with a pH value of 8.5, and 3 g of dopamine hydrochloride was added. The mixture was heated to 45°C, stirred for reaction for 5 h, separated by a magnet, washed, and dried to obtain modified carbon nanotube-deposited magnetic ferroferric oxide. S4. MnO 2 Deposition: 3g potassium permanganate was dissolved in 40mL water to obtain solution A, and 1.2g potassium manganate solution was dissolved in 100mL water to obtain solution B; 10g modified carbon nanotubes deposited magnetic ferroferric oxide was added to solution B, stirred and mixed for 20min, solution A was added dropwise, stirred and reacted at 170℃ for 20h, separated by magnet, washed, and dried to obtain MnO 2 / Carbon nanotubes deposit magnetic ferroferric oxide; S5. Intercalation of lanthanum and cerium: Dissolve 1 g of lanthanum nitrate and 0.5 g of cerium nitrate in 200 mL of water, add 35 g of MnO 2 / Carbon nanotubes were used to deposit magnetic ferrosoferric oxide, which was heated to 40°C and stirred for reaction for 1 hour. The catalyst was separated by a magnet, washed and dried to obtain a catalyst. Figure 1 This is the TEM image of the prepared catalyst. It can be seen from the image that a complex structure is formed, the surface has layered wrinkles, and it is loaded with a variety of particle structures.

[0022] Preparation Example 2 The catalyst was prepared as follows: S1. Preparation of magnetic ferroferric oxide: 3.24 g ferric chloride and 1.26 g ferrous chloride were added to 150 mL water, and 10 g ammonia water was added under nitrogen protection, and the mixture was heated to 90 ° C, stirred for 5 h, centrifuged, washed, dried, and calcined at 600 ° C for 3 h to obtain magnetic ferroferric oxide; S2. Chemical vapor deposition of carbon nanotubes: While heating 10g of magnetic ferroferric oxide, a mixture of hydrogen and nitrogen was introduced, wherein the volume ratio of the mixture of hydrogen and nitrogen was 4:10, and when the temperature was raised to 900°C, 8mL of a xylene solution of ferrocene was added dropwise, wherein the content of ferrocene in the xylene solution of ferrocene was 3wt%, and the reaction was kept at this temperature for 50min, and then cooled to room temperature, while only nitrogen was introduced to obtain magnetic ferroferric oxide deposited on carbon nanotubes; S3. Modification: 18 g of carbon nanotube-deposited magnetic ferroferric oxide was added to 200 mL of Tris-HCl solution with a pH value of 9.5, 5 g of dopamine hydrochloride was added, the mixture was heated to 55°C, stirred for reaction for 7 h, separated by a magnet, washed, and dried to obtain modified carbon nanotube-deposited magnetic ferroferric oxide; S4. MnO 2 Deposition: 5g potassium permanganate was dissolved in 40mL water to obtain liquid A, and 1.6g potassium manganate solution was dissolved in 100mL water to obtain liquid B; 10g modified carbon nanotubes deposited magnetic ferroferric oxide was added to liquid B, stirred and mixed for 20min, liquid A was added dropwise, stirred and reacted at 190℃ for 24h, separated by magnet, washed, and dried to obtain MnO 2 / Carbon nanotubes deposit magnetic ferroferric oxide; S5. Intercalation of lanthanum and cerium: Dissolve 2 g of lanthanum chloride and 1.5 g of cerium chloride in 200 mL of water, add 45 g of MnO 2 / Carbon nanotubes were used to deposit magnetic ferrosoferric oxide, which was heated to 50°C and stirred for reaction for 2 hours. The catalyst was separated by a magnet, washed and dried to obtain a catalyst.

[0023] Preparation Example 3 The preparation of the catalyst is as follows: S1. Preparation of magnetic ferroferric oxide: 3.24 g ferric chloride and 1.26 g ferrous chloride were added to 150 mL water, and 8.5 g ammonia water was added under nitrogen protection, heated to 85 ° C, stirred for 4 h, centrifuged, washed, dried, and calcined at 550 ° C for 2 h to obtain magnetic ferroferric oxide; S2. Chemical vapor deposition of carbon nanotubes: While heating 10 g of magnetic ferroferric oxide, a mixture of hydrogen and nitrogen was introduced, wherein the volume ratio of the mixture of hydrogen and nitrogen was 3:8, and when the temperature was raised to 850° C., 6 mL of a xylene solution of ferrocene was added dropwise, wherein the content of ferrocene in the xylene solution of ferrocene was 2.5 wt %, and the reaction was kept at this temperature for 40 min, and then cooled to room temperature, while only nitrogen was introduced to obtain magnetic ferroferric oxide deposited on carbon nanotubes; S3. Modification: 15 g of carbon nanotube-deposited magnetic ferroferric oxide was added to 200 mL of Tris-HCl solution with a pH value of 9, 4 g of dopamine hydrochloride was added, the mixture was heated to 50°C, stirred for 6 h, separated by a magnet, washed, and dried to obtain modified carbon nanotube-deposited magnetic ferroferric oxide; S4. MnO 2 Deposition: 4g potassium permanganate was dissolved in 40mL water to obtain liquid A, and 1.4g potassium manganate solution was dissolved in 100mL water to obtain liquid B; 10g modified carbon nanotubes deposited magnetic ferroferric oxide was added to liquid B, stirred and mixed for 20min, liquid A was added dropwise, stirred and reacted at 180℃ for 22h, separated by magnet, washed, and dried to obtain MnO 2 / Carbon nanotubes deposit magnetic ferroferric oxide; S5. Intercalation of lanthanum and cerium: Dissolve 1.5 g of lanthanum nitrate and 1 g of cerium nitrate in 200 mL of water, add 40 g of MnO 2 / Carbon nanotubes were used to deposit magnetic ferrosoferric oxide, which was heated to 45°C and stirred for reaction for 1.5 hours. The catalyst was separated by a magnet, washed and dried to obtain a catalyst.

[0024] Comparative Preparation Example 1 Compared with Preparation Example 3, the difference is that step S2 is not performed.

[0025] The preparation method is as follows: S1. Preparation of magnetic ferroferric oxide: 3.24 g ferric chloride and 1.26 g ferrous chloride were added to 150 mL water, and 8.5 g ammonia water was added under nitrogen protection, heated to 85 ° C, stirred for 4 h, centrifuged, washed, dried, and calcined at 550 ° C for 2 h to obtain magnetic ferroferric oxide; S2. Modification: 15 g of magnetic ferroferric oxide was added to 200 mL of Tris-HCl solution with a pH value of 9, 4 g of dopamine hydrochloride was added, the mixture was heated to 50°C, stirred for 6 h, separated by a magnet, washed, and dried to obtain modified magnetic ferroferric oxide; S3. MnO 2 Deposition: 4g potassium permanganate was dissolved in 40mL water to obtain liquid A, and 1.4g potassium manganate solution was dissolved in 100mL water to obtain liquid B; 10g modified magnetic ferroferric oxide was added to liquid B, stirred and mixed for 20min, liquid A was added dropwise, and the mixture was stirred and reacted at 180℃ for 22h, separated by magnet, washed, and dried to obtain MnO 2 Deposition of magnetic ferroferric oxide; S4. Intercalation of lanthanum and cerium: Dissolve 1.5 g of lanthanum nitrate and 1 g of cerium nitrate in 200 mL of water, add 40 g of MnO 2Deposit magnetic ferrosoferric oxide, heat to 45°C, stir and react for 1.5 hours, separate with a magnet, wash, and dry to obtain a catalyst.

[0026] Comparative Preparation Example 2 Compared with Preparation Example 3, the difference is that lanthanum nitrate is not added in step S5.

[0027] The preparation method is as follows: S1. Preparation of magnetic ferroferric oxide: 3.24 g ferric chloride and 1.26 g ferrous chloride were added to 150 mL water, and 8.5 g ammonia water was added under nitrogen protection, heated to 85 ° C, stirred for 4 h, centrifuged, washed, dried, and calcined at 550 ° C for 2 h to obtain magnetic ferroferric oxide; S2. Chemical vapor deposition of carbon nanotubes: While heating 10 g of magnetic ferroferric oxide, a mixture of hydrogen and nitrogen was introduced, wherein the volume ratio of the mixture of hydrogen and nitrogen was 3:8, and when the temperature was raised to 850° C., 6 mL of a xylene solution of ferrocene was added dropwise, wherein the content of ferrocene in the xylene solution of ferrocene was 2.5 wt %, and the reaction was kept at this temperature for 40 min, and then cooled to room temperature, while only nitrogen was introduced to obtain magnetic ferroferric oxide deposited on carbon nanotubes; S3. Modification: 15 g of carbon nanotube-deposited magnetic ferroferric oxide was added to 200 mL of Tris-HCl solution with a pH value of 9, 4 g of dopamine hydrochloride was added, the mixture was heated to 50°C, stirred for 6 h, separated by a magnet, washed, and dried to obtain modified carbon nanotube-deposited magnetic ferroferric oxide; S4. MnO 2 Deposition: 4g potassium permanganate was dissolved in 40mL water to obtain liquid A, and 1.4g potassium manganate solution was dissolved in 100mL water to obtain liquid B; 10g modified carbon nanotubes deposited magnetic ferroferric oxide was added to liquid B, stirred and mixed for 20min, liquid A was added dropwise, stirred and reacted at 180℃ for 22h, separated by magnet, washed, and dried to obtain MnO 2 / Carbon nanotubes deposit magnetic ferroferric oxide; S5. Intercalation of cerium: Dissolve 2.5 g of cerium nitrate in 200 mL of water and add 40 g of MnO 2 / Carbon nanotubes were used to deposit magnetic ferrosoferric oxide, which was heated to 45°C and stirred for reaction for 1.5 hours. The catalyst was separated by a magnet, washed and dried to obtain a catalyst.

[0028] Comparative Preparation Example 3 Compared with Preparation Example 3, the difference is that cerium nitrate is not added in step S5.

[0029] The preparation method is as follows: S1. Preparation of magnetic ferroferric oxide: 3.24 g ferric chloride and 1.26 g ferrous chloride were added to 150 mL water, and 8.5 g ammonia water was added under nitrogen protection, heated to 85 ° C, stirred for 4 h, centrifuged, washed, dried, and calcined at 550 ° C for 2 h to obtain magnetic ferroferric oxide; S2. Chemical vapor deposition of carbon nanotubes: While heating 10 g of magnetic ferroferric oxide, a mixture of hydrogen and nitrogen was introduced, wherein the volume ratio of the mixture of hydrogen and nitrogen was 3:8, and when the temperature was raised to 850° C., 6 mL of a xylene solution of ferrocene was added dropwise, wherein the content of ferrocene in the xylene solution of ferrocene was 2.5 wt %, and the reaction was kept at this temperature for 40 min, and then cooled to room temperature, while only nitrogen was introduced to obtain magnetic ferroferric oxide deposited on carbon nanotubes; S3. Modification: 15 g of carbon nanotube-deposited magnetic ferroferric oxide was added to 200 mL of Tris-HCl solution with a pH value of 9, 4 g of dopamine hydrochloride was added, the mixture was heated to 50°C, stirred for 6 h, separated by a magnet, washed, and dried to obtain modified carbon nanotube-deposited magnetic ferroferric oxide; S4. MnO 2 Deposition: 4g potassium permanganate was dissolved in 40mL water to obtain liquid A, and 1.4g potassium manganate solution was dissolved in 100mL water to obtain liquid B; 10g modified carbon nanotubes deposited magnetic ferroferric oxide was added to liquid B, stirred and mixed for 20min, liquid A was added dropwise, stirred and reacted at 180℃ for 22h, separated by magnet, washed, and dried to obtain MnO 2 / Carbon nanotubes deposit magnetic ferroferric oxide; S5. Lanthanum intercalation: Dissolve 2.5 g of lanthanum nitrate in 200 mL of water and add 40 g of MnO 2 / Carbon nanotubes were used to deposit magnetic ferrosoferric oxide, which was heated to 45°C and stirred for reaction for 1.5 hours. The catalyst was separated by a magnet, washed and dried to obtain a catalyst.

[0030] Comparative Preparation Example 4 Compared with Preparation Example 3, the difference is that step S5 is not performed.

[0031] The preparation method is as follows: S1. Preparation of magnetic ferroferric oxide: 3.24 g ferric chloride and 1.26 g ferrous chloride were added to 150 mL water, and 8.5 g ammonia water was added under nitrogen protection, heated to 85 ° C, stirred for 4 h, centrifuged, washed, dried, and calcined at 550 ° C for 2 h to obtain magnetic ferroferric oxide; S2. Chemical vapor deposition of carbon nanotubes: While heating 10 g of magnetic ferroferric oxide, a mixture of hydrogen and nitrogen was introduced, wherein the volume ratio of the mixture of hydrogen and nitrogen was 3:8, and when the temperature was raised to 850° C., 6 mL of a xylene solution of ferrocene was added dropwise, wherein the content of ferrocene in the xylene solution of ferrocene was 2.5 wt %, and the reaction was kept at this temperature for 40 min, and then cooled to room temperature, while only nitrogen was introduced to obtain magnetic ferroferric oxide deposited on carbon nanotubes; S3. Modification: 15 g of carbon nanotube-deposited magnetic ferroferric oxide was added to 200 mL of Tris-HCl solution with a pH value of 9, 4 g of dopamine hydrochloride was added, the mixture was heated to 50°C, stirred for 6 h, separated by a magnet, washed, and dried to obtain modified carbon nanotube-deposited magnetic ferroferric oxide; S4. MnO 2 Deposition: 4g potassium permanganate was dissolved in 40mL water to obtain liquid A, and 1.4g potassium manganate solution was dissolved in 100mL water to obtain liquid B; 10g modified carbon nanotubes deposited magnetic ferroferric oxide was added to liquid B, stirred and mixed for 20min, liquid A was added dropwise, stirred and reacted at 180℃ for 22h, separated by magnet, washed, and dried to obtain MnO 2 / Carbon nanotubes deposit magnetic ferroferric oxide, which serves as a catalyst.

[0032] Preparation Example 4 The preparation of the purifying agent is as follows: T1. Preparation of modified molecular imprinting polymer: 3g nicotinic acid, 15g monomer, 0.1g ethylene glycol dimethacrylate and 0.5g acetone were mixed, 0.01g potassium persulfate was added under nitrogen protection, and the mixture was heated to 50°C for polymerization reaction for 3h. The mixture was filtered, dried and ground to obtain a polymer, which was then added to a Soxhlet extractor and eluted with a washing liquid until nicotinic acid could not be detected. The polymer particles were washed and sieved to collect 50 mesh particles and dried to obtain a modified molecular imprinting polymer. The monomers include silane coupling agent A151 and butyl methacrylate in a mass ratio of 3:12; The washing liquid is a mixture of ethanol and acetic acid in a volume ratio of 100:3; T2. TiO 2 / ZnO loading: 3 g of tetrabutyl titanate and 2 g of zinc acetate were added to 150 mL of ethanol, and 50 mL of an aqueous solution containing 1.2 g of citric acid was added dropwise, and the pH value of the solution was adjusted to 9.5. The reaction was stirred at 35 °C for 2 h, centrifuged, washed, dried, and calcined at 450 °C for 2 h. The product was added to 200 mL of water, and 10 g of the modified molecularly imprinted polymer was added. The mixture was heated to 40 °C and stirred for 1 h to obtain the loaded TiO 2 / ZnO molecular imprinted polymer; T3. Doping: 12g of TiO 2The molecular imprinting polymer of ZnO was added into 100 mL of aqueous solution containing 3 g of graphene oxide, 0.1 g of ferric chloride and 0.12 g of cadmium nitrate were added, and 1 g of dithiol was added. The mixture was stirred for 15 min and spray-dried to obtain a purifying agent.

[0033] Preparation Example 5 The preparation of the purifying agent is as follows: T1. Preparation of modified molecular imprinting polymer: 5g nicotinic acid, 20g monomer, 0.2g ethylene glycol dimethacrylate and 1g acetone were mixed, 0.015g sodium persulfate was added under nitrogen protection, and the mixture was heated to 60°C for polymerization reaction for 5h. The mixture was filtered, dried and ground to obtain a polymer, which was then added to a Soxhlet extractor and eluted with a washing liquid until nicotinic acid could not be detected. The polymer particles were washed and sieved to collect 100 mesh particles and dried to obtain a modified molecular imprinting polymer. The monomers include silane coupling agent A171 and butyl methacrylate in a mass ratio of 5:15; The washing liquid is a mixture of ethanol and acetic acid in a volume ratio of 100:5; T2. TiO 2 / ZnO loading: 5 g of tetrabutyl titanate and 4 g of zinc acetate were added to 150 mL of ethanol, and 50 mL of an aqueous solution containing 1.5 g of citric acid was added dropwise, and the pH value of the solution was adjusted to 10.5. The reaction was stirred at 45 °C for 4 h, centrifuged, washed, dried, and calcined at 550 °C for 4 h. The product was added to 200 mL of water, and 12 g of the modified molecularly imprinted polymer was added. The mixture was heated to 50 °C and stirred for 2 h to obtain the loaded TiO 2 / ZnO molecular imprinted polymer; T3. Doping: 15g of TiO 2 The molecular imprinting polymer of ZnO was added into 100 mL of aqueous solution containing 5 g of graphene oxide, 0.2 g of ferric nitrate and 0.15 g of cadmium nitrate were added, and 2 g of dithiol was added. The mixture was stirred for 15 min and spray-dried to obtain a purifying agent.

[0034] Preparation Example 6 The preparation of the purifying agent is as follows: T1. Preparation of modified molecular imprinting polymer: 4g nicotinic acid, 17g monomer, 0.15g ethylene glycol dimethacrylate and 0.7g acetone were mixed, 0.012g ammonium persulfate was added under nitrogen protection, and the mixture was heated to 55°C for 4h of polymerization reaction. The mixture was filtered, dried and ground to obtain a polymer, which was then added to a Soxhlet extractor and eluted with a washing liquid until nicotinic acid could not be detected. The polymer particles were washed and sieved to collect 60 mesh particles and dried to obtain a modified molecular imprinting polymer. The monomers include silane coupling agent KH570 and butyl methacrylate in a mass ratio of 4:13; The washing liquid is a mixture of ethanol and acetic acid in a volume ratio of 100:4; T2. TiO 2 / ZnO loading: 4 g of tetrabutyl titanate and 3 g of zinc acetate were added to 150 mL of ethanol, and 50 mL of an aqueous solution containing 1.35 g of citric acid was added dropwise, the pH value of the solution was adjusted to 10, and the reaction was stirred at 40 °C for 3 h, centrifuged, washed, dried, and calcined at 500 °C for 3 h. The product was added to 200 mL of water, and 11 g of modified molecularly imprinted polymer was added, heated to 45 °C, and stirred for 1.5 h to obtain loaded TiO 2 / ZnO molecular imprinted polymer; T3. Doping: 13g of TiO 2 The molecular imprinted polymer of ZnO was added into 100 mL of aqueous solution containing 4 g of graphene oxide, 0.15 g of ferric nitrate and 0.13 g of cadmium nitrate were added, and 1.5 g of dithiol was added. The mixture was stirred for 15 min and spray-dried to obtain a purifying agent.

[0035] Comparative Preparation Example 5 Compared with Preparation Example 6, the difference is that the monomer in step T1 is single butyl methacrylate.

[0036] Comparative Preparation Example 6 Compared with Preparation Example 6, the difference is that tetrabutyl titanate is not added in step T2, and step T3 is not performed.

[0037] The preparation method is as follows: T1. Preparation of modified molecular imprinting polymer: 4g nicotinic acid, 17g monomer, 0.15g ethylene glycol dimethacrylate and 0.7g acetone were mixed, 0.012g ammonium persulfate was added under nitrogen protection, and the mixture was heated to 55°C for 4h of polymerization reaction. The mixture was filtered, dried and ground to obtain a polymer, which was then added to a Soxhlet extractor and eluted with a washing liquid until nicotinic acid could not be detected. The polymer particles were washed and sieved to collect 60 mesh particles and dried to obtain a modified molecular imprinting polymer. The monomers include silane coupling agent KH570 and butyl methacrylate in a mass ratio of 4:13; The washing liquid is a mixture of ethanol and acetic acid in a volume ratio of 100:4; T2. Loading of ZnO: 7 g of zinc acetate was added to 150 mL of ethanol, and 50 mL of an aqueous solution containing 1.35 g of citric acid was added dropwise, the pH value of the solution was adjusted to 10, and the mixture was stirred at 40°C for 3 h, centrifuged, washed, dried, and calcined at 500°C for 3 h. The product was added to 200 mL of water, and 11 g of the modified molecularly imprinted polymer was added, heated to 45°C, and stirred for 1.5 h to obtain a molecularly imprinted polymer loaded with ZnO; T3. Doping: 13 g of ZnO-loaded molecular imprinting polymer was added to 100 mL of an aqueous solution containing 4 g of graphene oxide, 0.15 g of ferric nitrate and 0.13 g of cadmium nitrate, and 1.5 g of dithiol were added, the mixture was stirred for 15 min, and spray-dried to obtain a purifying agent.

[0038] Comparative Preparation Example 7 Compared with Preparation Example 6, the difference is that zinc acetate and citric acid are not added in step T2.

[0039] The preparation method is as follows: T1. Preparation of modified molecular imprinting polymer: 4g nicotinic acid, 17g monomer, 0.15g ethylene glycol dimethacrylate and 0.7g acetone were mixed, 0.012g ammonium persulfate was added under nitrogen protection, and the mixture was heated to 55°C for 4h of polymerization reaction. The mixture was filtered, dried and ground to obtain a polymer, which was then added to a Soxhlet extractor and eluted with a washing liquid until nicotinic acid could not be detected. The polymer particles were washed and sieved to collect 60 mesh particles and dried to obtain a modified molecular imprinting polymer. The monomers include silane coupling agent KH570 and butyl methacrylate in a mass ratio of 4:13; The washing liquid is a mixture of ethanol and acetic acid in a volume ratio of 100:4; T2. TiO 2 Loading: 7 g of tetrabutyl titanate was added to 150 mL of ethanol, and 50 mL of water was added dropwise. The pH value of the solution was adjusted to 10, and the reaction was stirred at 40 ° C for 3 h, centrifuged, washed, dried, and calcined at 500 ° C for 3 h. The product was added to 200 mL of water, and 11 g of modified molecularly imprinted polymer was added. The mixture was heated to 45 ° C and stirred for 1.5 h to obtain the loaded TiO 2 Molecularly imprinted polymers; T3. Doping: 13g of TiO 2 The molecular imprinting polymer was added to 100 mL of an aqueous solution containing 4 g of graphene oxide, 0.15 g of ferric nitrate and 0.13 g of cadmium nitrate were added, and 1.5 g of dithiol was added. The mixture was stirred for 15 minutes and spray-dried to obtain a purifying agent.

[0040] Comparative Preparation Example 8 Compared with Preparation Example 6, the difference is that step T3 is not performed.

[0041] The preparation method is as follows: T1. Preparation of modified molecular imprinting polymer: 4g nicotinic acid, 17g monomer, 0.15g ethylene glycol dimethacrylate and 0.7g acetone were mixed, 0.012g ammonium persulfate was added under nitrogen protection, and the mixture was heated to 55°C for 4h of polymerization reaction. The mixture was filtered, dried and ground to obtain a polymer, which was then added to a Soxhlet extractor and eluted with a washing liquid until nicotinic acid could not be detected. The polymer particles were washed and sieved to collect 60 mesh particles and dried to obtain a modified molecular imprinting polymer. The monomers include silane coupling agent KH570 and butyl methacrylate in a mass ratio of 4:13; The washing liquid is a mixture of ethanol and acetic acid in a volume ratio of 100:4; T2. TiO 2 / ZnO loading: 4 g of tetrabutyl titanate and 3 g of zinc acetate were added to 150 mL of ethanol, and 50 mL of an aqueous solution containing 1.35 g of citric acid was added dropwise, the pH value of the solution was adjusted to 10, and the reaction was stirred at 40 °C for 3 h, centrifuged, washed, dried, and calcined at 500 °C for 3 h. The product was added to 200 mL of water, and 11 g of modified molecularly imprinted polymer was added, heated to 45 °C, and stirred for 1.5 h to obtain loaded TiO 2 / ZnO molecular imprinted polymer is the purifying agent.

[0042] Comparative Preparation Example 9 Compared with Preparation Example 6, the difference is that no iron nitrate is added in step T3.

[0043] The details are as follows: T3. Doping: 13g of TiO 2 The molecular imprinted polymer of ZnO was added into 100 mL of aqueous solution containing 4 g of graphene oxide, 0.28 g of cadmium nitrate and 1.5 g of dithiol were added, the mixture was stirred for 15 min, and the mixture was spray-dried to obtain a purifying agent.

[0044] Comparative Preparation Example 10 Compared with Preparation Example 6, the difference is that cadmium nitrate is not added in step T3.

[0045] The details are as follows: T3. Doping: 13g of TiO 2 The molecularly imprinted polymer of ZnO was added into 100 mL of an aqueous solution containing 4 g of graphene oxide, 0.28 g of ferric nitrate and 1.5 g of dithiol were added, the mixture was stirred for 15 min, and the mixture was spray-dried to obtain a purifying agent.

[0046] Example 1 This embodiment provides a method for preparing high-purity nicotinamide, comprising the following steps: 10 g of 3-aminomethylpyridine and 2 g of the catalyst prepared in Preparation Example 1 were added to 200 mL of toluene, and ozone was introduced at a flow rate of 8 mL / min. The mixture was heated to 45° C. and stirred for 6 h. The catalyst was separated by a magnet, washed, dried, and reused. 0.5 g of the purifying agent prepared in Preparation Example 4 was added to the liquid, and the mixture was stirred and reacted for 1 h at a temperature of 40° C. The mixture was filtered, and the solid purifying agent obtained by filtration was washed, dried, and reused. The filtrate was cooled to 0° C., filtered, and the solid was washed and dried to obtain high-purity nicotinamide.

[0047] Example 2 This embodiment provides a method for preparing high-purity nicotinamide, comprising the following steps: 10 g of 3-aminomethylpyridine and 3 g of the catalyst obtained in Preparation Example 2 were added to 200 mL of toluene, and ozone was introduced at a flow rate of 15 mL / min. The mixture was heated to 55° C. and stirred for 10 h. The catalyst was separated by a magnet, washed, dried, and reused. 1.5 g of the purifying agent obtained in Preparation Example 5 was added to the liquid, and the mixture was stirred and reacted for 2 h. The mixture was filtered, and the solid purifying agent obtained by filtration was washed, dried, and reused. The filtrate was cooled to 4° C., filtered, and the solid was washed and dried to obtain high-purity nicotinamide.

[0048] Example 3 This embodiment provides a method for preparing high-purity nicotinamide, comprising the following steps: 10 g of 3-aminomethylpyridine and 2.5 g of the catalyst obtained in Preparation Example 3 were added to 200 mL of toluene, and ozone was introduced at a flow rate of 11 mL / min. The mixture was heated to 50° C. and stirred for 8 h. The catalyst was separated by a magnet, washed, dried, and reused. 1 g of the purifying agent obtained in Preparation Example 6 was added to the liquid, and the mixture was stirred and reacted for 1.5 h at a temperature of 40 ° C. The mixture was filtered, and the solid purifying agent obtained by filtration was washed, dried, and reused. The filtrate was cooled to 2° C., filtered, and the solid was washed and dried to obtain high-purity nicotinamide.

[0049] Comparative Examples 1-4 Compared with Example 3, the difference is that the catalysts are prepared from Comparative Preparation Examples 1-4 respectively.

[0050] Comparative Examples 5-10 Compared with Example 3, the difference is that the purifying agents are prepared from Comparative Preparation Examples 5-10 respectively.

[0051] Comparative Example 11 The difference compared with Example 3 is that no catalyst is added.

[0052] Comparative Example 12 Compared with Example 3, the difference is that ozone is not introduced.

[0053] Comparative Example 13 Compared with Example 3, the difference is that no purifying agent is added.

[0054] Test Example 1 The reactions in Examples 1-3 and Comparative Examples 1-13 were evaluated, the weight of the nicotinamide obtained was weighed, the yield was calculated, and the purity was tested. The results are shown in Table 1.

[0055] Table 1

[0056] It can be seen from the above table that the nicotinamide prepared in Examples 1-3 of the present invention has a high yield and high purity.

[0057] In Comparative Example 1, compared with Example 3, the catalyst was prepared without the deposition of carbon nanotubes, and its yield was reduced. A layered carbon nanotube structure was deposited on its surface by chemical vapor deposition, which increased the specific surface area of ​​the catalyst. After subsequent intercalation of lanthanum and cerium ions, the loading amount of lanthanum and cerium ions was increased, which greatly expanded the catalytic active sites and improved the catalytic efficiency.

[0058] Compared with Example 3, in Comparative Examples 2 and 3, lanthanum nitrate or cerium nitrate was not added in the preparation of the catalyst, and in Comparative Example 4, step S5 was not performed in the preparation of the catalyst compared with Example 3, and the yield of nicotinamide decreased. The intercalation of lanthanum and cerium ions can improve the oxidation catalytic performance of the catalyst, and the two rare earth elements have a synergistic effect.

[0059] Comparative Example 5 Compared with Example 3, during the preparation of the purifying agent, KH570 was not added in the preparation of the molecularly imprinted polymer, and the purity of nicotinamide decreased. It can be seen that the TiO2 loaded on the molecularly imprinted polymer 2 / ZnO decreases, which reduces the decomposition rate of the adsorbed nicotinic acid and reduces the purification efficiency.

[0060] Compared with Example 3, in Comparative Examples 6 and 7, tetrabutyl titanate or zinc acetate was not added during the preparation of the purifying agent, and the purity thereof decreased. It can be seen that titanium dioxide and zinc oxide have a synergistic photocatalytic degradation effect on nicotinic acid, and have a good photocatalytic degradation effect, which can catalytically degrade the nicotinic acid loaded thereon.

[0061] Compared with Example 3, in Comparative Example 8, step T3 was not performed during the preparation of the purifying agent. Compared with Example 3, in Comparative Examples 9 and 10, no iron nitrate or cadmium nitrate was added during the preparation of the purifying agent, and the purity of nicotinamide decreased. It can be seen that the utilization rate of titanium dioxide for visible light is not high. In order to solve this problem, the present invention doped iron and cadmium ions and loaded dithiol. The formed thiol bonds complexed iron and cadmium ions, synergistically reduced the band gap width, and significantly enhanced the visible light response, sensitized titanium dioxide, and the doping of S changed the hybridization of the O 2p orbital and the Ti 3d orbital, thereby improving the stability of the doping.

[0062] In Comparative Examples 11 and 12, a single catalyst or ozone was used for catalysis, and the yield was significantly reduced. It can be seen that the present invention uses a catalyst and ozone for synergistic catalysis, and its catalytic effect is the best, which can make the reaction yield of nicotinamide reach more than 98%. However, the catalytic effect of a single catalyst and ozone catalysis is significantly reduced, which shows that the two have a synergistic effect.

[0063] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing high-purity nicotinamide, characterized in that: The following steps are involved: 3-Aminomethylpyridine and a catalyst are added to a solvent, ozone is introduced, the reaction is heated and stirred, the catalyst is separated by a magnet, washed and dried, and the reaction is repeated, a purifying agent is added to the liquid, the reaction is stirred and heated, and the solution is filtered, the solid purifying agent obtained by filtration is washed, dried, and reused, the filtrate is cooled, filtered, the solid is washed, and dried to obtain high-purity nicotinamide.

2. The method for preparing high-purity nicotinamide according to claim 1, characterized in that: The mass ratio of the 3-aminomethylpyridine, the catalyst and the purifying agent is 10:2-3:0.5-1.5, the temperature of the heating and stirring reaction is 45-55°C, the time is 6-10h, the time of the heat preservation and stirring reaction is 1-2h, the temperature is cooled to 0-4°C, and the ozone ventilation rate is 8-15mL / min.

3. The method for preparing high-purity nicotinamide according to claim 1, characterized in that: The preparation method of the catalyst is as follows: S1. Preparation of magnetic ferroferric oxide: ferric chloride and ferrous chloride are added to water, and under the protection of inert gas, ammonia is added, heated and stirred for reaction, centrifuged, washed, dried, and calcined to obtain magnetic ferroferric oxide; S2. Chemical vapor deposition of carbon nanotubes: heating magnetic ferroferric oxide while introducing a mixture of hydrogen and an inert gas, and when the temperature reaches a suitable temperature, adding a xylene solution of ferrocene dropwise, keeping the temperature for reaction, cooling while introducing only an inert gas, to obtain carbon nanotubes deposited with magnetic ferroferric oxide; S3. Modification: adding the carbon nanotube deposited magnetic ferroferric oxide to a Tris-HCl solution, adding dopamine hydrochloride, heating and stirring the reaction, separating with a magnet, washing, and drying to obtain a modified carbon nanotube deposited magnetic ferroferric oxide; S4. Deposition of MnO2: Dissolve potassium permanganate in water to obtain solution A, and dissolve potassium permanganate in water to obtain solution B; add the modified carbon nanotubes deposited magnetic ferroferric oxide to solution B, stir and mix evenly, add solution A dropwise, stir and react hydrothermally, separate with a magnet, wash, and dry to obtain MnO2 / carbon nanotubes deposited magnetic ferroferric oxide; S5. Intercalation of lanthanum and cerium: Dissolve lanthanum salt and cerium salt in water, add MnO2 / carbon nanotubes to deposit magnetic ferrosoferric oxide, heat and stir to react, separate with a magnet, wash, and dry to obtain a catalyst.

4. The method for preparing high-purity nicotinamide according to claim 3, characterized in that: The mass ratio of ferric chloride, ferrous chloride and ammonia water in step S1 is 3.24:1.26:7-10, the temperature of the heating and stirring reaction is 80-90°C, the time is 3-5h, the temperature of the calcination is 500-600°C, and the time is 1-3h; the mass volume ratio of the xylene solution of magnetic ferrosinite and ferrocene in step S2 is 10g:5-8mL, the content of ferrocene in the xylene solution of ferrocene is 2-3wt%, the volume ratio of hydrogen and inert gas mixture is 2-4:7-10, the suitable temperature is 800-900°C, and the insulation reaction time is 30-50min.

5. The method for preparing high-purity nicotinamide according to claim 3, characterized in that: In step S3, the mass ratio of magnetic ferroferric oxide deposited by carbon nanotubes, dopamine hydrochloride and catalyst is 12-18:3-5, the pH value of the Tris-HCl solution is 8.5-9.5, the temperature of the heating and stirring reaction is 45-55°C, and the time is 5-7h; in step S4, the mass ratio of potassium permanganate, potassium manganate and modified carbon nanotube-deposited magnetic ferroferric oxide is 3-5:1.2-1.6:10, the temperature of the hydrothermal stirring reaction is 170-190°C, and the time is 20-24h; in step S5, the lanthanum salt is lanthanum nitrate or lanthanum chloride, the cerium salt is cerium nitrate or cerium chloride, the mass ratio of the lanthanum salt, cerium salt and MnO2 / carbon nanotube-deposited magnetic ferroferric oxide is 1-2:0.5-1.5:35-45, the temperature of the heating and stirring reaction is 40-50°C, and the time is 1-2h.

6. The method for preparing high-purity nicotinamide according to claim 1, characterized in that: The preparation method of the purifying agent is as follows: T1. Preparation of modified molecular imprinted polymer: nicotinic acid, monomer, crosslinking agent and porogen are mixed, initiator is added under inert gas protection, polymerization reaction is heated, filtered, dried and ground to obtain polymer, which is then added to a Soxhlet extractor, eluted with washing liquid until nicotinic acid is undetectable, polymer particles are washed, sieved, 50-100 mesh particles are collected, and dried to obtain modified molecular imprinted polymer; T2. Loading of TiO2 / ZnO: Tetrabutyl titanate and zinc acetate were added to ethanol, and citric acid aqueous solution was added dropwise, the pH value of the solution was adjusted, stirred for reaction, centrifuged, washed, dried, calcined, the product was added to water, and the modified molecular imprinting polymer was added, heated and stirred for reaction, and a molecular imprinting polymer loaded with TiO2 / ZnO was obtained; T3. Doping: adding the molecular imprinting polymer loaded with TiO2 / ZnO to the graphene oxide aqueous solution, adding iron salt and cadmium salt, adding dithiol, stirring and mixing evenly, spray drying, and obtaining a purifying agent.

7. The method for preparing high-purity nicotinamide according to claim 6, characterized in that: In step T1, the mass ratio of nicotinic acid, monomer, cross-linking agent, porogen and initiator is 3-5:15-20:0.1-0.2:0.5-1:0.01-0.015, the initiator is selected from at least one of sodium persulfate, potassium persulfate, ammonium persulfate and benzoyl peroxide, the monomer comprises a silane coupling agent with a double bond and butyl methacrylate, the mass ratio is 3-5:12-15, the silane coupling agent with a double bond is selected from at least one of KH570, A151 and A171, the porogen is acetone, the cross-linking agent is ethylene glycol dimethacrylate, the temperature of the heating polymerization reaction is 50-60°C, the time is 3-5h, and the washing liquid is a mixture of ethanol and acetic acid in a volume ratio of 100:3-5.

8. The method for preparing high-purity nicotinamide according to claim 6, characterized in that: In step T2, the mass ratio of tetrabutyl titanate, zinc acetate, citric acid and modified molecular imprinted polymer is 3-5:2-4:1.2-1.5:10-12, the pH value of the adjusted solution is 9.5-10.5, the stirring reaction time is 2-4h, the temperature is 35-45°C, the calcination temperature is 450-550°C, the time is 2-4h, and the heating stirring reaction temperature is 40-50°C, and the time is 1-2h.

9. The method for preparing high-purity nicotinamide according to claim 6, characterized in that: In step T3, the mass ratio of the TiO2 / ZnO-loaded molecular imprinted polymer, graphene oxide, iron salt, cadmium salt and dithiol is 12-15:3-5:0.1-0.2:0.12-0.15:1-2, the iron salt is ferric nitrate or ferric chloride, and the cadmium salt is cadmium nitrate.

10. The method for preparing high-purity nicotinamide according to claim 1, characterized in that: The purity of the high-purity nicotinamide is >99.9%.

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