Iron monatomic catalyst for efficiently and directionally converting rifamycin B to O and application of iron monatomic catalyst

Abstract

The invention discloses an iron monatomic catalyst for efficiently and directionally converting rifamycin B to O and application of the iron monatomic catalyst, and belongs to the technical field of environmental engineering, chemical engineering and material engineering. The iron monatomic microenvironment is regulated through sulfur, and the catalyst capable of directionally regulating an electron transfer path in conversion from rifamycin B to O is developed. In order to solve the regulation and control problem of a specific functional group targeted dehydrogenation reaction path in rifamycin B-to-O conversion, the electron transfer intensity and sites are precisely regulated and controlled by adjusting the sulfur-iron coordination mode and content, and finally efficient directional conversion is achieved. According to the iron monatomic catalyst prepared by the method, the conversion yield of rifamycin from B to O can reach 91.35%, the product purity reaches 95%, and the iron monatomic catalyst is superior to the prior art.

Description

Technical Field

[0001] The present invention belongs to the technical fields of environmental engineering, chemical engineering and materials engineering, and particularly relates to an iron single-atom catalyst for efficiently and directionally converting rifamycin B to O and its application. Background Art

[0002] Rifamycin antibiotics are the first-line drugs in the treatment of tuberculosis, and play an important role in the anti-tuberculosis field with their strong efficacy and broad antibacterial properties. Rifamycin B is the synthetic raw material of many rifamycin antibiotics. Its strong water solubility and toxicity make the high-concentration pharmaceutical wastewater generated difficult to treat. Rifamycin O is the oxidation product of rifamycin B. It is insoluble in water and has been widely used in the rifamycin pharmaceutical industry as an important synthetic intermediate (such as rifaximin). Realizing the efficient and directional conversion of rifamycin B to O can not only detoxify the high-concentration rifamycin B pharmaceutical wastewater, but also highly value-recover the rifamycin O pharmaceutical intermediate, which is of great significance for the pretreatment of high-concentration antibiotic wastewater and the development of rifamycin antibiotics.

[0003] Traditional methods of adding oxidants (such as sodium persulfate) to promote the conversion of rifamycin B to O can only achieve a mass yield of about 80%. Appropriate addition of a certain amount of butyl acetate before the reaction can promote the conversion and achieve a mass yield of 85%. For a long time, due to the complex matrix effect in high-concentration pharmaceutical wastewater (COD>60000 mg / L) and the difficulty in regulating electron transfer, it has been difficult to further improve the mass yield of this conversion. The glycolic carboxyl group and naphthalene ring hydroxyl group in the rifamycin B molecule have significant chemical activities. By designing a specific dehydrogenation reaction path and precisely regulating the electron transfer between sodium persulfate (PDS) and the rifamycin B molecule, it is expected to further achieve a higher mass yield.

[0004] An iron single-atom catalyst regulated by sulfur (S) coordination can be prepared by combining a hydrothermal process through a wet chemical method. By introducing S to regulate the microenvironment of the iron single atom, changing the conductivity of the catalyst and the adsorption configuration between rifamycin B and the catalyst, thereby regulating the intensity and action sites in the process of electron transfer from rifamycin B to the catalyst and then to the oxidant, realizing the directional regulation of the oxidation electron transfer process from rifamycin B to O, and reducing the occurrence of side reactions while achieving efficient and directional conversion. This iron single-atom catalyst can achieve a conversion yield of 91.35% from rifamycin B to O, and the product purity reaches 95%, which is superior to the existing process. Summary of the Invention

[0005] The purpose of the present invention is to provide an iron single-atom catalyst for efficiently and directionally converting rifamycin B to O and its application in view of the deficiencies of the prior art.

[0006] The purpose of the present invention is achieved by the following technical solutions: In a first aspect, the present invention provides an iron single-atom catalyst for efficiently and directionally converting rifamycin B to O, and the iron single-atom catalyst for efficiently and directionally converting rifamycin B to O is prepared by the following steps: Dissolve 3.1 - 3.5 g of melamine in 300 - 350 mL of deionized water at 80 - 95 °C to form solution a, dissolve 2.5 - 3.0 g of cyanuric acid in 200 - 250 mL of deionized water at 80 - 95 °C to form solution b, weigh 0.4 - 0.5 g of oxalic acid and 0.5 - 0.6 g of ferric nitrate nonahydrate, dissolve them in 50 - 80 mL of deionized water and mix well to prepare solution c; inject solution b and solution c into solution a and stir for 4 - 5 h to obtain solution d, then perform suction filtration to obtain precursor A1, wash and dry it, and then perform the first calcination in an inert atmosphere to obtain precursor A2; take 0.5 - 0.7 g of precursor A2, 4.1 - 4.5 g of glucose and 35 - 50 mL of ultrapure water, mix them and perform a hydrothermal reaction, then separate the solid and liquid to obtain a solid and dry it, and finally perform the second calcination on the dried solid in an inert atmosphere to obtain the iron single-atom catalyst for efficiently and directionally converting rifamycin B to O, denoted as iron 1.

[0007] Further, the washing is specifically: washing three times with deionized water and alcohol respectively.

[0008] Further, the inert atmosphere is argon or nitrogen.

[0009] Further, the first calcination is specifically: the heating rate is 3 - 5 °C / min, the calcination temperature is 600 - 650 °C, and the calcination time is 4 - 5 h.

[0010] Further, the hydrothermal reaction is specifically: the temperature of the hydrothermal reaction is 180 - 200 °C, and the time of the hydrothermal reaction is 10 - 12 h.

[0011] Further, the second calcination is specifically: the heating rate is 3 - 5 °C / min, the calcination temperature is 900 - 950 °C, and the calcination time is 4 - 5 h.

[0012] In a second aspect, the present invention provides an iron single-atom catalyst for efficiently and directionally converting rifamycin B to O, and the iron single-atom catalyst for efficiently and directionally converting rifamycin B to O is prepared by the following steps: Dissolve 3.1 - 3.5 g of melamine in 300 - 350 mL of deionized water at 80 - 95 °C to form solution a, dissolve 2.5 - 3.0 g of cyanuric acid in 200 - 300 mL of deionized water at 80 - 95 °C to form solution b, weigh 0.5 - 0.8 g of N - allylthiourea and 0.4 - 0.6 g of ferrous acetate, dissolve them in 50 - 70 mL of deionized water and mix well to prepare solution c; inject solution b and solution c into solution a and stir for 4 - 5 h to obtain solution d, then perform suction filtration to obtain precursor B1, wash and dry it, and then perform the first calcination in an inert atmosphere to obtain precursor B2; take 0.5 - 0.7 g of precursor B2, 4.1 - 4.5 g of glucose and 35 - 40 mL of ultrapure water, mix them and perform a hydrothermal reaction, then separate the solid and liquid phases to obtain a solid product and dry it. Finally, perform the second calcination on the dried solid product in an inert atmosphere to obtain an iron single - atom catalyst for efficiently and directionally converting rifamycin B to O, denoted as iron - sulfur 1.

[0013] Further, the washing is specifically as follows: Wash three times with deionized water and alcohol respectively.

[0014] Further, the inert atmosphere is argon or nitrogen.

[0015] Further, the first calcination is specifically as follows: The heating rate is 3 - 5 °C / min, the calcination temperature is 600 - 650 °C, and the calcination time is 4 - 5 h.

[0016] Further, the hydrothermal reaction is specifically as follows: The temperature of the hydrothermal reaction is 180 - 200 °C, and the time of the hydrothermal reaction is 10 - 12 h.

[0017] Further, the second calcination is specifically as follows: The heating rate is 3 - 5 °C / min, the calcination temperature is 900 - 950 °C, and the calcination time is 4 - 5 h.

[0018] In a third aspect, the present invention provides an iron single - atom catalyst for efficiently and directionally converting rifamycin B to O, and the iron single - atom catalyst for efficiently and directionally converting rifamycin B to O is prepared by the following steps: Dissolve 3.1 - 3.5 g of melamine in 300 - 350 mL of deionized water at 90 - 95 °C to form solution a, dissolve 2.5 - 3.0 g of cyanuric acid in 200 - 300 mL of deionized water at 90 - 95 °C to form solution b, weigh 0.4 - 0.5 g of thiocyanic acid and dissolve it in 50 - 80 mL of dimethyl sulfoxide to obtain solution c, weigh 0.85 - 0.95 g of iron acetylacetonate and dissolve it in 90 - 100 mL of N,N - dimethylformamide to obtain solution d; inject solution b, solution c and solution d into solution a and stir for 4 - 6 h to obtain solution e, then perform suction filtration to obtain precursor C1, wash and dry it, and then perform the first calcination in an inert atmosphere to obtain precursor C2; take 0.5 - 0.7 g of precursor C2, 4.1 - 4.3 g of glucose and 35 - 50 mL of ultrapure water, mix them and perform a hydrothermal reaction, then perform solid - liquid separation to obtain a solid and dry it, and finally perform the second calcination on the dried solid in an inert atmosphere to obtain an iron single - atom catalyst for efficiently and directionally converting rifamycin B to O, denoted as iron - sulfur 2.

[0019] Further, the washing is specifically as follows: Wash three times with deionized water and alcohol respectively.

[0020] Further, the inert atmosphere is argon or nitrogen.

[0021] Further, the first calcination is specifically as follows: The heating rate is 3 - 5 °C / min, the calcination temperature is 600 - 650 °C, and the calcination time is 4 - 5 h.

[0022] Further, the hydrothermal reaction is specifically as follows: The temperature of the hydrothermal reaction is 180 - 200 °C, and the time of the hydrothermal reaction is 10 - 12 h.

[0023] Further, the second calcination is specifically as follows: The heating rate is 3 - 5 °C / min, the calcination temperature is 900 - 950 °C, and the calcination time is 4 - 5 h.

[0024] Fourthly, the present invention provides an application of an iron single - atom catalyst for efficiently and directionally converting rifamycin B to O in the efficient and directional conversion of rifamycin B to rifamycin O.

[0025] Further, the application includes the following specific steps: In the feed liquid containing rifamycin B, an iron single-atom catalyst for efficiently and directionally converting rifamycin B to O is added, and after magnetic stirring for 30 - 40 min, a mixed solution is obtained. Sodium persulfate is added, and activation conversion is carried out for 1 - 1.5 h to complete the efficient and directional conversion of rifamycin B to rifamycin O; the concentration of rifamycin B in the feed liquid is 15000 - 18000 mg / L; the dosage of the iron single-atom catalyst for efficiently and directionally converting rifamycin B to O is 1.5 - 2 g / L; the dosage of sodium persulfate is 130 - 140 mM.

[0026] The beneficial effects of the present invention are as follows: 1) By introducing S element to regulate the coordination environment of iron single atoms, the efficient activation of sodium persulfate is achieved to regulate the electron transfer process from rifamycin B to rifamycin O. 2) The doping of S element changes the conductivity of the catalyst and the adsorption configuration between rifamycin B and the catalyst, thereby regulating the intensity and action sites in the process of electron transfer from rifamycin B to the catalyst and then to the oxidant, achieving efficient and directional conversion while reducing the occurrence of side reactions. Description of the Drawings

[0027] Figure 1 Schematic diagram of the coordination structure of the iron single-atom catalyst prepared in Example 1; Figure 2 Schematic diagram of the coordination structure of the iron single-atom catalyst prepared in Example 2; Figure 3 Schematic diagram of the coordination structure of the iron single-atom catalyst prepared in Example 3; Figure 4 X-ray diffraction pattern of the iron single-atom catalysts prepared in Example 1, Example 2, and Example 3; Figure 5 R-space X-ray extended X-ray absorption fine structure spectrum of the Fourier transform Fe K-edge of the iron single-atom catalysts prepared in Example 1, Example 2, and Example 3, Fe foil, FePc, and FeS; Figure 6 Graph showing the change of the mass yield of rifamycin O with the increase of the addition amount of sodium persulfate without adding the iron single-atom catalyst; Figure 7 Experimental graph of the mass yield of rifamycin O; Figure 8 Experimental graph of the purity of rifamycin O; Figure 9 Graph showing the change of the mass yield of rifamycin O with the increase of the S / Fe ratio in the iron single-atom catalyst prepared in Example 3. Detailed Embodiments

[0028] In order to make the objectives, technical solutions and advantages of the present invention more clear and understandable, the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention, rather than all embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the protection scope of the present invention.

[0029] The test methods without specific experimental conditions mentioned below are generally carried out according to conventional experimental conditions or the experimental conditions recommended by the manufacturer. The materials, reagents, etc. used, unless otherwise specified, are materials and reagents obtained from commercial channels.

[0030] In a first aspect, the present invention provides a method for preparing an iron single-atom catalyst for efficiently and directionally converting rifamycin B to O, comprising the following steps: Dissolve 3.1 - 3.5 g of melamine in 300 - 350 mL of deionized water under magnetic stirring at 80 - 95 °C to form solution a, dissolve 2.5 - 3.0 g of cyanuric acid in 200 - 250 mL of deionized water under magnetic stirring at 80 - 95 °C to form solution b, weigh 0.4 - 0.5 g of oxalic acid and 0.5 - 0.6 g of ferric nitrate nonahydrate, dissolve them in 50 - 80 mL of deionized water and mix well to prepare solution c; inject solution b and solution c into solution a and stir for 4 - 5 h to obtain solution d; then perform suction filtration on solution d to obtain precursor A1, wash precursor A1 three times each with deionized water and alcohol, and then dry it at 70 - 75 °C for 24 - 26 h; subsequently, place the dried precursor A1 in a tube furnace, heat it to 600 - 650 °C at a heating rate of 3 - 5 °C / min under a flowing inert atmosphere, calcine for 4 - 5 h, take it out after cooling to obtain precursor A2; take 0.5 - 0.7 g of precursor A2, 4.1 - 4.5 g of glucose and 35 - 50 mL of ultrapure water, mix them and add them into the inner liner of a reaction kettle, perform hydrothermal reaction at 180 - 200 °C for 10 - 12 h, then perform solid-liquid separation to obtain a solid; then dry the solid at 70 - 75 °C for 24 - 26 h, and then place the dried solid in a tube furnace, heat it to 900 - 950 °C at a heating rate of 3 - 5 °C / min in an inert atmosphere and calcine for 4 - 5 h to finally obtain an iron single-atom catalyst for efficiently and directionally converting rifamycin B to O, denoted as iron 1. The inert atmosphere is argon or nitrogen.

[0031] In a second aspect, the present invention further provides a method for preparing an iron single-atom catalyst for efficiently and directionally converting rifamycin B to O, comprising the following steps: Dissolve 3.1 - 3.5 g of melamine in 300 - 350 mL of deionized water under magnetic stirring at 80 - 95 °C to form solution a. Dissolve 2.5 - 3.0 g of cyanuric acid in 200 - 300 mL of deionized water under magnetic stirring at 80 - 95 °C to form solution b. Weigh 0.5 - 0.8 g of N - allylthiourea and 0.4 - 0.6 g of ferrous acetate, dissolve them in 50 - 70 mL of deionized water and mix well to prepare solution c. Inject solution b and solution c into solution a and stir for 4 - 5 h to obtain solution d. Then, perform suction filtration on solution d to obtain precursor B1, and wash precursor B1 three times each with deionized water and alcohol. Subsequently, dry it at 70 - 80 °C for 24 - 26 h. Then, place the dried precursor B1 in a tube furnace and heat it to 600 - 650 °C at a heating rate of 3 - 5 °C / min under a flowing argon atmosphere, calcine for 4 - 5 h, take it out after cooling to obtain precursor B2. Take 0.5 - 0.7 g of precursor B2, 4.1 - 4.5 g of glucose and 35 - 40 mL of ultrapure water, mix them and add them into the inner liner of a reaction kettle. After hydrothermal reaction at 180 - 200 °C for 10 - 12 h, perform solid - liquid separation to obtain a solid. Subsequently, dry the solid at 60 - 70 °C for 24 - 26 h, then place the dried solid in a tube furnace and heat it to 900 - 950 °C at a heating rate of 3 - 5 °C / min in an argon atmosphere and calcine for 4 - 5 h to finally obtain an iron single - atom catalyst for efficiently and directionally converting rifamycin B to O, denoted as iron - sulfur 1. The inert atmosphere is argon or nitrogen.

[0032] Thirdly, the present invention also provides a preparation method of an iron single - atom catalyst for efficiently and directionally converting rifamycin B to O, comprising the following steps: Dissolve 3.1 - 3.5 g of melamine in 300 - 350 mL of deionized water under magnetic stirring at 90 - 95 °C to form solution a. Dissolve 2.5 - 3.0 g of cyanuric acid in 200 - 300 mL of deionized water under magnetic stirring at 90 - 95 °C to form solution b. Weigh 0.4 - 0.5 g of thiocyanic acid and dissolve it in 50 - 80 mL of dimethyl sulfoxide to obtain solution c. Weigh 0.85 - 0.95 g of ferric acetylacetonate and dissolve it in 90 - 100 mL of N,N - dimethylformamide to obtain solution d. Inject solution b, solution c, and solution d into solution a and stir for 4 - 5 h to obtain solution e. Filter solution e to obtain precursor C1, and wash precursor C1 three times each with deionized water and alcohol. Then dry it at 70 - 80 °C for 24 - 26 h. Subsequently, place the dried precursor C1 in a tube furnace and heat it to 600 - 650 °C at a heating rate of 3 - 5 °C / min in a flowing argon atmosphere, calcine for 4 - 5 h, and take it out after cooling to obtain precursor C2. Take 0.5 - 0.7 g of precursor C2, 4.1 - 4.3 g of glucose, and 35 - 50 mL of ultrapure water, mix them and add them into the inner liner of a reaction kettle. After hydrothermal reaction at 180 - 190 °C for 10 - 12 h, perform solid - liquid separation to obtain a solid. Then dry the solid at 70 - 80 °C for 24 - 26 h, and place the dried solid in a tube furnace and heat it to 900 - 950 °C at a heating rate of 3 - 5 °C / min in an argon atmosphere for calcination for 4 - 5 h to finally obtain an iron single - atom catalyst for the efficient directional conversion of rifamycin B to O, denoted as iron - sulfur 2. The inert atmosphere is argon or nitrogen.

[0033] Example 1: The iron single - atom catalyst (iron 1) for the efficient directional conversion of rifamycin B to O was prepared through the following steps: Dissolve 3.1 g of melamine in 300 mL of deionized water under magnetic stirring at 80 °C to form solution a. Dissolve 2.5 g of cyanuric acid in 200 mL of deionized water under magnetic stirring at 80 °C to form solution b. Weigh 0.4 g of oxalic acid and 0.5 g of ferric nitrate nonahydrate, dissolve them in 50 mL of deionized water, and mix well to prepare solution c. Slowly inject solution b and solution c into solution a and stir for 4 h to obtain solution d. Then, perform suction filtration on solution d to obtain precursor A1, and wash precursor A1 three times each with deionized water and alcohol. Subsequently, dry it at 70 °C for 24 h. Then, place the dried precursor A1 in a tubular furnace, heat it to 600 °C at a heating rate of 5 °C / min under a flowing argon atmosphere, calcine for 4 h, take it out after cooling to obtain precursor A2. Take 0.5 g of precursor A2, 4.1 g of glucose, and 35 mL of ultrapure water, mix them, add them into the inner liner of the reaction kettle, perform hydrothermal reaction at 180 °C for 10 h, and then separate the solid and liquid to obtain a solid substance. Subsequently, dry the solid substance at 70 °C for 24 h, then place the dried solid substance in a tubular furnace, heat it to 900 °C at a heating rate of 5 °C / min in an argon atmosphere, and calcine for 4 h to finally obtain an iron single-atom catalyst for efficiently and directionally converting rifamycin B to O, denoted as iron 1.

[0034] Example 2 The iron single-atom catalyst (iron-sulfur 1) for efficiently and directionally converting rifamycin B to O is prepared through the following steps: Dissolve 3.1 g of melamine in 300 mL of deionized water under magnetic stirring at 80 °C to form solution a. Dissolve 2.5 g of cyanuric acid in 200 mL of deionized water under magnetic stirring at 80 °C to form solution b. Weigh 0.5 g of N-allylthiourea and 0.4 g of ferrous acetate, dissolve them in 50 mL of deionized water, and mix well to prepare solution c. Slowly inject solution b and solution c into solution a and stir for 4 h to obtain solution d. Then, perform suction filtration on solution d to obtain precursor B1, and wash precursor B1 three times each with deionized water and alcohol. Subsequently, dry it at 70 °C for 24 h. Then, place the dried precursor B1 in a tubular furnace, heat it to 600 °C at a heating rate of 3 °C / min under a flowing argon atmosphere, calcine for 4 h, take it out after cooling to obtain precursor B2. Take 0.5 g of precursor B2, 4.1 g of glucose, and 35 mL of ultrapure water, mix them, add them into the inner liner of the reaction kettle, perform hydrothermal reaction at 180 °C for 10 h, and then separate the solid and liquid to obtain a solid substance. Subsequently, dry the solid substance at 60 °C for 24 h, then place the dried solid substance in a tubular furnace, heat it to 900 °C at a heating rate of 5 °C / min in an argon atmosphere, and calcine for 4 h to finally obtain an iron single-atom catalyst for efficiently and directionally converting rifamycin B to O, denoted as iron-sulfur 1.

[0035] Example 3 The iron single-atom catalyst (iron-sulfur 2) for efficiently and directionally converting rifamycin B to O is prepared through the following steps: Dissolve 3.1 g of melamine in 300 mL of deionized water under magnetic stirring at 90 °C to form solution a. Dissolve 2.5 g of cyanuric acid in 200 mL of deionized water under magnetic stirring at 90 °C to form solution b. Weigh 0.4 g of thiocyanic acid and dissolve it in 50 mL of dimethyl sulfoxide to obtain solution c. Weigh 0.85 g of iron acetylacetonate and dissolve it in 90 mL of N,N-dimethylformamide to obtain solution d. Slowly inject solution b, solution c, and solution d into solution a and stir for 4 h to obtain solution e. Perform suction filtration on solution e to obtain precursor C1, and wash precursor C1 three times each with deionized water and alcohol, and then dry it at 70 °C for 24 h. Subsequently, place the dried precursor C1 in a tube furnace and heat it to 600 °C at a heating rate of 5 °C / min under a flowing argon atmosphere, calcine for 4 h, take it out after cooling to obtain precursor C2. Take 0.5 g of precursor C2, 4.1 g of glucose, and 35 mL of ultrapure water, mix them and add them into the inner liner of the reaction kettle. After hydrothermal reaction at 180 °C for 10 h, perform solid-liquid separation to obtain a solid. Subsequently, dry the solid at 70 °C for 24 h. Place the dried solid in a tube furnace and heat it to 900 °C at a heating rate of 5 °C / min in an argon atmosphere and calcine for 4 h to finally obtain an iron single-atom catalyst for the efficient directional conversion of rifamycin B to O, denoted as iron-sulfur 2. By changing the added mass of thiocyanic acid to 0.08 g, 0.16 g, 0.32 g, 0.4 g, 0.6 g, 0.7 g, and 0.9 g, iron-sulfur 2 with S / Fe ratios of 0.2:1, 0.4:1, 0.8:1, 1:1, 1.5:1, 2:1, and 3:1 can be prepared.

[0036] Application Example 1 Transformation experiment of rifamycin B to O by activating sodium persulfate with different catalysts (iron 1, iron-sulfur 1, iron-sulfur 2) (1) Take 50 mL of rifamycin B feed solution and add it to a 100 mL beaker. Respectively add the iron single-atom catalyst (iron 1) prepared in Example 1, the iron single-atom catalyst (iron-sulfur 1) prepared in Example 2, and the iron single-atom catalyst (iron-sulfur 2) prepared in Example 3 at 2 g / L for ultrasonic dispersion. After adding 5 wt% of butyl acetate (1.5 mL) and magnetic stirring for 30 min, add sodium persulfate with a concentration of 140 mM.

[0037] (2) Start timing after adding sodium persulfate. After 1 h, add 30 mL of butyl acetate as an extraction agent to the beaker, stir for 5 min, then pour it into a separatory funnel for liquid separation. After standing for 4 h, obvious stratification appears. Take the upper butyl acetate phase for detection.

[0038] (3) Use a high-performance liquid chromatograph to measure the concentrations of rifamycin O and impurities in the butyl acetate phase, and thus calculate the mass yield and purity of rifamycin O.

[0039] Figure 1Schematic diagram of the coordination structure of the iron single-atom catalyst prepared in Example 1; Figure 2 Schematic diagram of the coordination structure of the iron single-atom catalyst prepared in Example 2; Figure 3 Schematic diagram of the coordination structure of the iron single-atom catalyst prepared in Example 3. As Figure 1 shown, the iron single-atom catalyst prepared in Example 1 has a classical Fe-N4 configuration, and each iron atom coordinates with four nitrogen atoms; as Figure 2 shown, a sulfur atom is introduced into the iron single-atom catalyst prepared in Example 2 to directly coordinate with iron, and the coordination environment of iron becomes the Fe-SN3 configuration, which triggers the splitting of the 3d orbitals of Fe and the enhancement of spin electron rearrangement, enhancing the adsorption of the targeted hydroxyl group of rifamycin B by the Fe site; as Figure 3 shown, a sulfur atom is introduced into the iron single-atom catalyst prepared in Example 3 to coordinate with N on the carrier, and the coordination environment of iron becomes the Fe-N4S configuration. While triggering the splitting of the 3d orbitals of Fe, the positive charge of the central Fe is enhanced through the remote electron-withdrawing effect of sulfur, thus achieving the best adsorption effect of the Fe site on the targeted hydroxyl group of rifamycin B.

[0040] Figure 4 X-ray diffraction patterns of the iron single-atom catalysts prepared in Example 1, Example 2, and Example 3. As Figure 4 shown, the iron single-atom catalysts prepared in Example 1, Example 2, and Example 3 basically maintain the structure of nitrogen-doped carbon, and no diffraction peaks of iron nanoparticles appear, proving that iron exists in the form of small-sized atoms in each iron single-atom catalyst. Figure 5 R-space X-ray extended X-ray absorption fine structure spectra of the Fourier transform Fe K-edge of the iron single-atom catalysts, iron foil (Fe foil), FePc, and FeS prepared in Example 1, Example 2, and Example 3. As Figure 5 shown, it is found that an obvious characteristic peak corresponding to Fe-N coordination scattering appears at 1.4 Å for iron 1 and iron sulfur 2, while the dominant peak of iron sulfur 1 corresponds to the Fe-S coordination bond of the FeS standard product, indicating the existence of the Fe-S coordination configuration inside iron sulfur 1. Figure 6 Graph showing the change of the mass yield of rifamycin O with the increase in the addition amount of sodium persulfate without adding the iron single-atom catalyst; Figure 6 It shows that without adding the iron single-atom catalyst, the mass yield of rifamycin O increases with the increase in the addition amount of sodium persulfate. However, when the addition amount reaches 140 mM, increasing the addition amount of sodium persulfate can no longer improve the yield, reaching a bottleneck, and at this time, the mass yield of rifamycin O reaches 80%. Figure 7 Experimental graph of the mass yield of rifamycin O; Figure 8 Experimental graph of the purity of rifamycin O; Figure 7It is shown that when 5 wt% of butyl acetate, 2 g / L of the iron single-atom catalyst prepared in Example 3, and 140 mM of sodium persulfate are added, the mass yield of rifamycin O reaches a maximum of 91.35%; Figure 8 It is shown that when 5 wt% of butyl acetate, 2 g / L of the iron single-atom catalyst prepared in Example 3, and 140 mM of sodium persulfate are added, the purity of rifamycin O reaches a maximum of 94.97%, which is better than the existing process. Figure 9 It is a graph showing the change of the mass yield of rifamycin O with the increase of the S / Fe ratio in the iron single-atom catalyst prepared in Example 3; Figure 9 It is shown that the mass yield of rifamycin O changes with the different S / Fe ratios in the iron single-atom catalyst prepared in Example 3. When the S / Fe ratio in the iron single-atom catalyst prepared in Example 3 is 1:1, the optimal mass yield is 91.35%.

[0041] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the scope of protection of the present invention.

Claims

1. An iron single-atom catalyst for efficient directional conversion of rifamycin B to O, characterized in that: The iron single-atom catalyst for efficient and directional conversion of rifamycin B to O is prepared by the following steps: 3.1-3.5 g of melamine was dissolved in 300-350 mL of deionized water at 80-95° C. to form solution a, 2.5-3.0 g of cyanuric acid was dissolved in 200-250 mL of deionized water at 80-95° C. to form solution b, 0.4-0.5 g of oxalic acid and 0.5-0.6 g of ferric nitrate nonahydrate were weighed and dissolved in 50-80 mL of deionized water and mixed to prepare solution c; solution b and solution c were injected into solution a and stirred for 4-5 h to obtain solution d, which was filtered to obtain precursor A1, which was washed and dried, and then first calcined in an inert atmosphere to obtain precursor A2; 0.5-0.7 g of precursor A2, 4.1-4.5 g of glucose and 35-50 mL of The reaction mixture is mixed with ultrapure water and subjected to a hydrothermal reaction, followed by solid-liquid separation to obtain a solid and drying the solid. Finally, the dried solid is subjected to a second calcination in an inert atmosphere to obtain an iron single atom catalyst for the efficient directional conversion of rifamycin B to O, which is recorded as iron 1.

2. An iron single-atom catalyst for efficient directional conversion of rifamycin B to O, characterized in that: The iron single-atom catalyst for efficient and directional conversion of rifamycin B to O is prepared by the following steps: 3.1-3.5 g of melamine was dissolved in 300-350 mL of deionized water at 80-95 °C to form solution a, 2.5-3.0 g of cyanuric acid was dissolved in 200-300 mL of deionized water at 80-95 °C to form solution b, 0.5-0.8 g of N-allylthiourea and 0.4-0.6 g of ferrous acetate were weighed and dissolved in 50-70 mL of deionized water and mixed to prepare solution c; solution b and solution c were injected into solution a and stirred for 4-5 h to obtain solution d, which was filtered to obtain precursor B1, which was washed and dried, and then first calcined in an inert atmosphere to obtain precursor B2; 0.5-0.7 g of precursor B2, 4.1-4.5 g of glucose and 35-40 mL of Ultrapure water is mixed and a hydrothermal reaction is carried out, followed by solid-liquid separation to obtain a solid and drying it, and finally the dried solid is subjected to a second calcination in an inert atmosphere to obtain an iron single-atom catalyst for the efficient and directional conversion of rifamycin B to O, which is recorded as iron-sulfur 1.

3. An iron single-atom catalyst for efficient directional conversion of rifamycin B to O, characterized in that: The iron single-atom catalyst for efficient and directional conversion of rifamycin B to O is prepared by the following steps: 3.1-3.5 g of melamine was dissolved in 300-350 mL of deionized water at 90-95° C. to form solution a, 2.5-3.0 g of cyanuric acid was dissolved in 200-300 mL of deionized water at 90-95° C. to form solution b, 0.4-0.5 g of thiocyanic acid was weighed and dissolved in 50-80 mL of dimethyl sulfoxide to obtain solution c, 0.85-0.95 g of ferric acetylacetonate was weighed and dissolved in 90-100 mL of N,N-dimethylformamide to obtain solution d; solution b, solution c and solution d were injected into solution a and stirred for 4-6 h to obtain solution e, which was filtered to obtain precursor C1, which was washed and dried, and then first calcined in an inert atmosphere to obtain precursor C2; 0.5-0.7 g of precursor C2, 4.1-4.3 g of glucose and 35-50 mL of Ultrapure water is mixed and a hydrothermal reaction is carried out, followed by solid-liquid separation to obtain a solid and drying it, and finally the dried solid is subjected to a second calcination in an inert atmosphere to obtain an iron single-atom catalyst for the efficient and directional conversion of rifamycin B to O, which is recorded as iron-sulfur 2.

4. The iron single-atom catalyst for efficient directional conversion of rifamycin B to O according to claim 1, 2 or 3, characterized in that: The washing is specifically: washing with deionized water and alcohol three times each.

5. The iron single atom catalyst for efficient directional conversion of rifamycin B to O according to claim 1, 2 or 3, characterized in that: The inert atmosphere is argon or nitrogen.

6. The iron single-atom catalyst for efficient directional conversion of rifamycin B to O according to claim 1, 2 or 3, characterized in that: The first calcination is specifically as follows: the heating rate is 3-5°C / min, the calcination temperature is 600-650°C, and the calcination time is 4-5h.

7. The iron single-atom catalyst for efficient directional conversion of rifamycin B to O according to claim 1, 2 or 3, characterized in that: The hydrothermal reaction is specifically as follows: the temperature of the hydrothermal reaction is 180-200° C., and the time of the hydrothermal reaction is 10-12 hours.

8. The iron single-atom catalyst for efficient directional conversion of rifamycin B to O according to claim 1, 2 or 3, characterized in that: The second calcination is specifically as follows: the heating rate is 3-5°C / min, the calcination temperature is 900-950°C, and the calcination time is 4-5h.

9. Use of the iron single-atom catalyst for efficient directional conversion of rifamycin B to O as claimed in claim 1, 2 or 3 for efficient directional conversion of rifamycin B to rifamycin O.

10. The use according to claim 9, characterized in that: The application comprises the following specific steps: An iron single-atom catalyst for efficient directional conversion of rifamycin B to O is added to a rifamycin B-containing liquid, and a mixed solution is obtained after magnetic stirring for 30 to 40 minutes, and sodium persulfate is added to activate and convert for 1 to 1.5 hours to complete the efficient directional conversion of rifamycin B to rifamycin O; The concentration of rifamycin B in the feed solution is 15000-18000 mg / L; the dosage of the iron single atom catalyst for high-efficiency directional conversion of rifamycin B to O is 1.5-2 g / L; and the dosage of the sodium persulfate is 130-140 mM.

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