N-doped manganese-magnesium binary oxide and its preparation method and application

Abstract

The present invention prepares a single-atom nitrogen-doped magnesium-manganese binary oxide catalyst, and applies the catalyst to catalytic ozone oxidation to remove acetic acid. The present invention utilizes the characteristic that nitrogen has lower electronegativity than oxygen, performs single-atom doping to enhance the catalytic ozone activity of the magnesium-manganese binary oxide catalyst, and nitrogen doping reduces the amount of basic site lattice oxygen of the magnesium-manganese binary oxide, thereby improving the stability of the magnesium-manganese binary oxide in water.

Description

(I) Technical field

[0001] The invention relates to the field of preparation of doped catalysts, in particular to a preparation method of a single-atom doped magnesium-manganese binary oxide catalyst and a method for treating acetic acid by catalytic ozone treatment. (II) Background technology

[0002] With the development and progress of analytical detection technology, emerging organic pollutants such as drugs, personal care products, pesticides, hormones, and food additives have been detected in natural water bodies. Most emerging pollutants cannot be biodegraded and pose potential hazards to human health. Advanced oxidation technology can produce oxygen-containing free radicals with strong oxidizing ability, which can directly mineralize organic matter in wastewater or improve the biodegradability of organic pollutants. Ozone advanced oxidation technology is one of the most promising methods for treating organic refractory wastewater. Solid base MgO has the advantages of homogeneous and heterogeneous catalytic ozone action. During the MgO-catalyzed ozone reaction, the pH of the solution will be significantly increased to alkaline, thereby promoting the decomposition of ozone to produce oxygen-containing free radicals. Experiments have shown that MgO has surface active potentials that catalyze the decomposition of ozone to produce oxygen-containing free radicals. However, the hydration of MgO will affect the stability of MgO-catalyzed ozone. MgO reacts with water to produce Mg(OH)2, which is slightly soluble in water and has a lower catalytic ozone activity than MgO. Studies have found that the catalytic ozone activity of solid bases is proportional to its alkalinity, while its alkalinity is inversely proportional to stability. In addition, some studies have found that the alkaline earth metal element Mg and the transition metal element Mn form a bimetallic oxide magnesium manganate, which overcomes the contradiction between the activity and stability of solid base catalytic ozone, and proposes the mechanism of acid-base synergistic catalytic ozone reaction. The introduction of the transition metal element Mn appropriately reduces the alkalinity of the catalyst, and at the same time, the acidic site - the low-valent transition metal ion (Mn 2+ , Mn 3+ ) reacts with ozone to generate oxygen-containing free radicals with the help of protonated hydroxyl groups at the basic position. Therefore, magnesium manganate has higher catalytic ozone activity and stability than MgO.

[0003] Appropriately reducing the alkalinity of magnesium-manganese binary oxides, although affecting the activity of the alkaline sites, can reduce the hydration of the catalyst and improve the stability of the catalyst; at the same time, enhancing the electron transfer ability of the acidic sites of magnesium-manganese binary oxides, making up for the lost activity of the alkaline sites, maintaining or even improving the overall activity of the catalyst, thereby appropriately reducing the alkalinity of the catalyst and enhancing the catalytic ozone activity of the acidic sites is a design idea to further improve the catalytic ozone activity and stability of magnesium-manganese binary oxides. Therefore, the selection of non-metallic elements with less electronegativity than oxygen to be doped into magnesium-transition metal binary oxides provides feasibility for further improving the catalytic ozone activity and stability of magnesium-manganese binary oxides.

[0004] In summary, the preparation of non-metallic single atom doped magnesium-manganese metal binary oxide and the study of its catalytic ozone performance are of great significance. The following problems still exist in the current research:

[0005] (1) There is a lack of information on the effects of non-metallic doping atoms on the acid-base chemical properties of magnesium-manganese binary oxides.

[0006] (2) There is a lack of research on the acid-base synergistic catalytic ozone activity and stability of magnesium-manganese binary oxides by non-metallic doping atoms.

[0007] Based on the above research background and ideas, this project intends to use single-element nitrogen doping to optimize the acid-base synergistic activity and stability of magnesium-manganese binary metal oxides as ozone water treatment catalysts, and to regulate the acid-base properties of magnesium-manganese binary metal oxides to improve the acid-base synergistic catalytic ozone activity and stability of the catalyst. The influence of single-atom nitrogen doping on the acid-base synergistic catalytic ozone activity and stability of magnesium-manganese binary metal oxides is studied. Through the implementation of this project, the design and synthesis of efficient and stable ozone water treatment catalysts can be achieved, the optimization mechanism of acid-base synergistic catalytic ozone of magnesium-manganese binary metal oxides can be constructed, and the development and application of heterogeneous catalytic ozone technology can be promoted. (III) Summary of the invention

[0008] In view of the stability problem of the catalyst, the purpose of the present invention is to prepare a single-atom nitrogen-doped magnesium-manganese binary oxide catalyst and apply it to catalyze ozone oxidation to remove acetic acid.

[0009] In order to achieve the above object, the present invention adopts the following technical solution:

[0010] In a first aspect, the present invention provides an N-doped manganese-magnesium binary oxide, wherein the N-doped manganese-magnesium binary oxide is prepared by the following method:

[0011] Dissolve magnesium nitrate and manganese nitrate in double distilled water, add NaOH solution dropwise, react at 70°C-120°C (preferably 90°C) with stirring for 1h-3h (preferably 2h), cool and centrifuge the obtained reaction solution, remove the lower precipitate, wash with water until the pH of the washing solution is less than 9, vacuum dry, grind to obtain a carrier, add an aqueous solution of a nitrogen source dropwise, mix thoroughly, let stand for 5h-15h (preferably 12h), and calcine at 200°C-800°C (preferably 500°C) for 1h-3h (preferably 2h) to obtain the N-doped manganese-magnesium binary oxide;

[0012] The molar ratio of the magnesium nitrate and the manganese nitrate is 1-2:1 (preferably 1:1); the molar ratio of the NaOH contained in the NaOH solution to the total molar ratio of the magnesium nitrate and the manganese nitrate is 6-12:1 (preferably 10.5:1); the volume of the aqueous solution of the nitrogen source is equal to the saturated water absorption capacity of the carrier; the nitrogen source contained in the aqueous solution of the nitrogen source is urea or cyanamide (preferably urea); the mass of the nitrogen source is 3-28% (preferably 19%) of the mass of the carrier based on its theoretical nitrogen content.

[0013] Furthermore, the volume of the double distilled water is 0.5-1.0 L / mol (preferably 0.75 L / mol) based on the sum of the amounts of magnesium nitrate and manganese nitrate.

[0014] Furthermore, the concentration of the NaOH solution is 4-8 mol / L (preferably 6 mol / L).

[0015] Preferably, the particle size of the carrier is 0.0385-0.05 mm, which can be obtained by sieving with 300 mesh and 400 mesh sieves in sequence.

[0016] The present invention also provides the use of the N-doped manganese-magnesium binary oxide as a catalyst in catalyzing ozone degradation of acetic acid in an acetic acid-containing solution.

[0017] The specific application is: adding the N-doped manganese-magnesium binary oxide into the acetic acid-containing solution, placing the obtained mixture in a reactor, and introducing ozone from the bottom of the reactor for degradation.

[0018] Preferably, the pH of the acetic acid solution is 5-9, preferably pH 5. Of course, certain effects can be achieved at other pH values. The concentration of the acetic acid solution is 20 mg / L, and the volume of the acetic acid solution is 2.5 L / g based on the mass of the N-doped manganese-magnesium binary oxide.

[0019] Specifically, in the embodiment of the present invention, ozone is introduced into the reactor in the form of a mixed gas of ozone and oxygen, the flow rate of the mixed gas is 0.5 L / min, and the concentration of ozone in the mixed gas is 40 mg / L.

[0020] The acetic acid-containing solution can be regarded as acetic acid-containing wastewater. The present invention analyzes the effect of the catalyst on catalytic degradation of acetic acid in different wastewaters by using acetic acid-containing solutions with different pH values.

[0021] The doping source of the present invention mainly selects a nitrogen source suitable for the equal volume impregnation method. If a nitrogen source with poor water solubility is used, the effect of equal volume impregnation cannot be achieved during impregnation, and excessive impregnation will cause the dissolution of Mg ions. The present invention selects urea or cyanamide as the nitrogen source because they have good water solubility and high nitrogen content. High nitrogen content can reduce the influence of carbon elements in the doping source and highlight the advantages of doped nitrogen. The solvent used in the present invention is deionized water. If a corresponding organic solvent is used, the organic solvent contains other elements such as carbon, which has an impact on the doping system and also has an impact on the subsequent degradation system.

[0022] The present invention also relates to the application of the nitrogen-doped magnesium-manganese binary oxide solid catalyst in catalytic ozone oxidation to remove acetic acid and actual wastewater. The use of the catalyst of the present invention can improve the removal rate of acetic acid.

[0023] When the single-atom nitrogen-doped magnesium-manganese binary oxide solid catalyst of the present invention is used to catalyze ozone oxidation of acetic acid in water, the process conditions are specifically carried out as follows: adjusting the pH of 250 mL of an aqueous solution containing 20 mg / L acetic acid to 5, 7, or 9, adding 400 mg / L of the single-atom nitrogen-doped magnesium-manganese binary oxide solid catalyst, introducing ozone to degrade acetic acid, the input amount of ozone is 40 mg / L, and the gas flow rate of ozone and oxygen is 0.5 L / min.

[0024] Compared with the prior art, the single-atom nitrogen-doped magnesium-manganese binary oxide solid catalyst of the present invention has the following beneficial effects in the O3-treated acetic acid solution:

[0025] (1) Taking advantage of the fact that nitrogen has a lower electronegativity than oxygen, single-atom doping is performed to enhance the catalytic ozone activity of the magnesium-manganese binary oxide catalyst. At the same time, nitrogen doping reduces the amount of lattice oxygen in the basic site of the magnesium-manganese binary oxide, thereby improving the stability of the magnesium-manganese binary oxide in water.

[0026] (2) The single-atom nitrogen-doped magnesium-manganese binary metal oxide solid catalyst can be used to treat water samples with different pH values. (IV) Specific implementation methods

[0027] The present invention is further described below in conjunction with specific embodiments, but the protection scope of the present invention is not limited thereto.

[0028] In the following examples, the ratio of Mg to Mn is 1:1 and the N doping amount is 3% MgMnO y -N is labeled as MgMnO y -N3, MgMnO doped with 7% N y -N is labeled as MgMnO y -N7, MgMnO with 12% N doping y-N is labeled as MgMnO y -N 12 , MgMnO with N doping content of 19% y -N is labeled as MgMnO y -N 19 , MgMnO with N doping content of 28% y -N is labeled as MgMnO y -N 28 MgMnO with a C doping content of 5% and a ratio of Mg to Mn in the ratio of 1:1 y -C is labeled as MgMnO y -C5, MgMnO doped with 10% C y -C is labeled as MgMnO y -C 10 , MgMnO doped with 15% C y -C is labeled as MgMnO y -C 15 .

[0029] Calculate the concentration of nitrogen source or C source solution by N / C doping amount. (Calculation formula: doping ratio = mass of N contained in nitrogen source / mass of catalyst precursor)

[0030] The ozone in the following examples was prepared in an ozone generator using oxygen as a raw material, and a mixed gas of ozone and oxygen was introduced when degrading acetic acid.

[0031] Example 1: Preparation of N-doped (urea) catalyst

[0032] (1) Weigh 15.38 g of Mg(NO3)2·6H2O solid and 21.47 g of Mn(NO3)2 solution and dissolve them in 90 mL of double distilled water (the amount of Mg and Mn substances is 0.06 mol each);

[0033] (2) Add 210 mL of NaOH solution (6 mol / L) dropwise to the above solution;

[0034] (3) stirring the solution obtained in step (2) in an oil bath in a temperature-controlled magnetic stirrer at 90° C. for 2 h;

[0035] (4) cooling the solution obtained in step (3) and centrifuging to obtain a lower layer of precipitated material, washing it with water and centrifuging it again, and repeating the washing and centrifugation until the pH of the supernatant liquid at the centrifuge is less than 9;

[0036] (5) The precipitate collected in step (4) was placed in a vacuum drying oven at 80° C. and dried for 12 h;

[0037] (6) The material obtained in step (5) was ground into powder and sieved to obtain catalyst powder of 0.0385 mm-0.05 mm. Deionized water was dripped into 1 g of the catalyst powder and stirred evenly until the volume of the solution was just enough to soak the carrier and there was no excess water on the surface of the soaked catalyst. The volume of the solution was measured to be 0.8 mL, which was the saturated water absorption capacity of the catalyst powder in this case.

[0038] (7) The amount of urea required for doping was calculated according to the N doping ratio of 3%, 7%, 12%, 19%, and 28%. 1 g of catalyst powder was weighed and placed in 0.8 mL of deionized water solution, 0.8 mL of urea aqueous solution with concentrations of 0.0804 g / mL, 0.1875 g / mL, 0.3214 g / mL, 0.5088 g / mL, and 0.7500 g / mL, respectively. The mixture was mixed and allowed to stand for 12 h.

[0039] (8) The material obtained in step (7) was placed in a muffle furnace and calcined at 500°C for 2h to obtain MgMnO y ,MgMnO y -N3,MgMnO y -N7,MgMnO y -N 12 ,MgMnO y -N 19 ,MgMnO y -N 28 Catalyst (urea as nitrogen source).

[0040] Prepare 250 mL of acetic acid solution containing 20 mg / L, adjust the pH to 5, and then add MgMnO y ,MgMnO y -N3,MgMnO y -N7,MgMnO y -N 12 ,MgMnO y -N 19 ,MgMnO y -N 28 The catalyst (urea as nitrogen source) was added in an amount of 0.1 g and then added into a columnar reactor, and ozone was introduced into the bottom of the reactor.

[0041] The ozone input was 40 mg / L (ozone concentration in the mixed gas), and the gas flow rate of ozone and oxygen was 0.5 L / min. At the beginning of the experiment, a sample was taken at 0 min, 3 min, 6 min, and 9 min for testing.

[0042] Detection method: Acetic acid was analyzed by ThermoFisher Dionex Ultimate3000 high performance liquid chromatography.

[0043] The results of pH 5 water sample treatment for 9 minutes are shown in Table 1:

[0044]

[0045] Table 1

[0046] Example 2: Preparation of N-doped (urea) catalyst

[0047] (1) Weigh 15.38 g of Mg(NO3)2·6H2O solid and 21.47 g of Mn(NO3)2 solution and dissolve them in 90 mL of double distilled water (the amount of Mg and Mn substances is 0.06 mol each);

[0048] (2) Add 210 mL of NaOH solution (6 mol / L) dropwise to the above solution;

[0049] (3) stirring the solution obtained in step (2) in an oil bath in a temperature-controlled magnetic stirrer at 90° C. for 2 h;

[0050] (4) cooling the solution obtained in step (3) and centrifuging to obtain a lower layer of precipitated material, washing it with water and centrifuging it again, and repeating the washing and centrifugation until the pH of the supernatant liquid at the centrifuge is less than 9;

[0051] (5) The precipitate collected in step (4) was placed in a vacuum drying oven at 80° C. and dried for 12 h;

[0052] (6) The material obtained in step (5) was ground into powder and sieved to obtain catalyst powder of 0.0385 mm-0.05 mm. Deionized water was dripped into 1 g of the catalyst powder and stirred evenly until the volume of the solution was just enough to soak the carrier and there was no excess water on the surface of the soaked catalyst. The volume of the solution was measured to be 0.8 mL, which was the saturated water absorption capacity of the catalyst powder in this case.

[0053] (7) The amount of urea required for doping was calculated according to the doping ratio of 3%, 7%, 12%, 19%, and 28%. 1 g of catalyst powder was weighed and placed in 0.8 mL of deionized water solution, 0.8 mL of urea aqueous solution with concentrations of 0.0804 g / mL, 0.1875 g / mL, 0.3214 g / mL, 0.5088 g / mL, and 0.7500 g / mL, respectively. The mixture was mixed and allowed to stand for 12 h.

[0054] (8) The material obtained in step (7) was placed in a muffle furnace and calcined at 500°C for 2h to obtain MgMnO y ,MgMnO y -N3,MgMnO y -N7,MgMnO y -N 12 ,MgMnOy -N 19 ,MgMnO y -N 28 Catalyst (urea as nitrogen source).

[0055] Prepare 250 mL of acetic acid solution containing 20 mg / L, adjust the pH to 7, and then add MgMnO y ,MgMnO y -N3,MgMnO y -N7,MgMnO y -N 12 ,MgMnO y -N 19 ,MgMnO y -N 28 The catalyst (urea as nitrogen source) was added in an amount of 0.1 g and then added into a columnar reactor, and ozone was introduced into the bottom of the reactor.

[0056] The ozone input was 40 mg / L (ozone concentration in the mixed gas), and the gas flow rate of ozone and oxygen was 0.5 L / min. At the beginning of the experiment, a sample was taken at 0 min, 3 min, 6 min, and 9 min for testing.

[0057] Detection method: Acetic acid was analyzed by ThermoFisher Dionex Ultimate3000 high performance liquid chromatography.

[0058] The results of pH7 water sample treatment for 9 minutes are shown in Table 2:

[0059]

[0060] Table 2

[0061] Example 3: Preparation of N-doped (urea) catalyst

[0062] (1) Weigh 15.38 g of Mg(NO3)2·6H2O solid and 21.47 g of Mn(NO3)2 solution and dissolve them in 90 mL of double distilled water (the amount of Mg and Mn substances is 0.06 mol each);

[0063] (2) Add 210 mL of NaOH solution (6 mol / L) dropwise to the above solution;

[0064] (3) stirring the solution obtained in step (2) in an oil bath in a temperature-controlled magnetic stirrer at 90° C. for 2 h;

[0065] (4) cooling the solution obtained in step (3) and centrifuging to obtain a lower layer of precipitated material, washing it with water and centrifuging it again, and repeating the washing and centrifugation until the pH of the supernatant liquid at the centrifuge is less than 9;

[0066] (5) The precipitate collected in step (4) was placed in a vacuum drying oven at 80° C. and dried for 12 h;

[0067] (6) The material obtained in step (5) was ground into powder and sieved to obtain catalyst powder of 0.0385 mm-0.05 mm. Deionized water was dripped into 1 g of the catalyst powder and stirred evenly until the volume of the solution was just enough to soak the carrier and there was no excess water on the surface of the soaked catalyst. The volume of the solution was measured to be 0.8 mL, which was the saturated water absorption capacity of the catalyst powder in this case.

[0068] (7) The amount of urea required for doping was calculated according to the doping ratio of 3%, 7%, 12%, 19%, and 28%. 1 g of catalyst powder was weighed and placed in 0.8 mL of deionized water solution, 0.8 mL of urea aqueous solution with a concentration of 0.0804 g / mL, 0.1875 g / mL, 0.3214 g / mL, 0.5088 g / mL, and 0.7500 g / mL, respectively. The mixture was mixed and allowed to stand for 12 h.

[0069] (8) The material obtained in step (7) was placed in a muffle furnace and calcined at 500°C for 2h to obtain MgMnO y ,MgMnO y -N3,MgMnO y -N7,MgMnO y -N 12 ,MgMnO y -N 19 ,MgMnO y -N 28 Catalyst (urea as nitrogen source).

[0070] Prepare 250 mL of acetic acid solution containing 20 mg / L, adjust the pH to 9, and then add MgMnO y ,MgMnO y -N3,MgMnO y -N7,MgMnO y -N 12 ,MgMnO y -N 19 ,MgMnO y -N 28 The catalyst (urea as nitrogen source) was added in an amount of 0.1 g and then added into a columnar reactor, and ozone was introduced into the bottom of the reactor.

[0071] The ozone input was 40 mg / L (ozone concentration in the mixed gas), and the gas flow rate of ozone and oxygen was 0.5 L / min. At the beginning of the experiment, a sample was taken at 0 min, 3 min, 6 min, and 9 min for testing.

[0072] Detection method: Acetic acid was analyzed by ThermoFisher Dionex Ultimate3000 high performance liquid chromatography.

[0073] The results of pH9 water sample treatment for 9 minutes are shown in Table 3:

[0074]

[0075] Table 3

[0076] Example 4: Preparation of N-doped (cyanamide) catalyst

[0077] (1) Weigh 15.38 g of Mg(NO3)2·6H2O solid and 21.47 g of Mn(NO3)2 solution and dissolve them in 90 mL of double distilled water (the amount of Mg and Mn substances is 0.06 mol each);

[0078] (2) Add 210 mL of NaOH solution (6 mol / L) dropwise to the above solution;

[0079] (3) stirring the solution obtained in step (2) in an oil bath in a temperature-controlled magnetic stirrer at 90° C. for 2 h;

[0080] (4) cooling the solution obtained in step (3) and centrifuging to obtain a lower layer of precipitated material, washing it with water and centrifuging it again, and repeating the washing and centrifugation until the pH of the supernatant liquid at the centrifuge is less than 9;

[0081] (5) The precipitate collected in step (4) was placed in a vacuum drying oven at 80° C. and dried for 12 h;

[0082] (6) The material obtained in step (5) was ground into powder and sieved to obtain catalyst powder of 0.0385 mm-0.05 mm. Deionized water was dripped into 1 g of the catalyst powder and stirred evenly until the volume of the solution was just enough to soak the carrier and there was no excess water on the surface of the soaked catalyst. The volume of the solution was measured to be 0.8 mL, which was the saturated water absorption capacity of the catalyst powder in this case.

[0083] (7) The amount of cyanamide required for doping was calculated according to the doping ratio of 3%, 7%, 12%, 19%, and 28%. 1 g of the catalyst powder was weighed and placed in 0.8 mL of deionized water solution, 0.8 mL of cyanamide aqueous solution with a concentration of 0.0563 g / mL, 0.1313 g / mL, 0.2250 g / mL, 0.3563 g / mL, and 0.5250 g / mL, respectively. The mixture was mixed and allowed to stand for 12 h.

[0084] (8) The material obtained in step (7) was placed in a muffle furnace and calcined at 500°C for 2 h to obtain MgMnO y ,MgMnO y-N3,MgMnO y -N7,MgMnO y -N 12 ,MgMnO y -N 19 ,MgMnO y -N 28 Catalyst (cyanamide as nitrogen source).

[0085] Prepare 250 mL of acetic acid solution containing 20 mg / L, adjust the pH to 5, and then add MgMnO y ,MgMnO y -N3,MgMnO y -N7,MgMnO y -N 12 ,MgMnO y -N 19 ,MgMnO y -N 28 The catalyst (cyanamide as nitrogen source) was added in an amount of 0.1 g and then added into a columnar reactor, and ozone was introduced into the bottom of the reactor.

[0086] The ozone input was 40 mg / L (ozone concentration in the mixed gas), and the gas flow rate of ozone and oxygen was 0.5 L / min. At the beginning of the experiment, a sample was taken at 0 min, 3 min, 6 min, and 9 min for testing.

[0087] Detection method: Acetic acid was analyzed by ThermoFisher Dionex Ultimate3000 high performance liquid chromatography.

[0088] The results of pH5 water sample treatment for 9 minutes are shown in Table 4:

[0089]

[0090] Table 4

[0091] Example 5: Preparation of N-doped (cyanamide) catalyst

[0092] (1) Weigh 15.38 g of Mg(NO3)2·6H2O solid and 21.47 g of Mn(NO3)2 solution and dissolve them in 90 mL of double distilled water (the amount of Mg and Mn substances is 0.06 mol each);

[0093] (2) Add 210 mL of NaOH solution (6 mol / L) dropwise to the above solution;

[0094] (3) stirring the solution obtained in step (2) in an oil bath in a temperature-controlled magnetic stirrer at 90° C. for 2 h;

[0095] (4) cooling the solution obtained in step (3) and centrifuging to obtain a lower layer of precipitated material, washing it with water and centrifuging it again, and repeating the washing and centrifugation until the pH of the supernatant liquid at the centrifuge is less than 9;

[0096] (5) The precipitate collected in step (4) was placed in a vacuum drying oven at 80° C. and dried for 12 h;

[0097] (6) The material obtained in step (5) was ground into powder and sieved to obtain catalyst powder of 0.0385 mm-0.05 mm. Deionized water was dripped into 1 g of the catalyst powder and stirred evenly until the volume of the solution was just enough to soak the carrier and there was no excess water on the surface of the soaked catalyst. The volume of the solution was measured to be 0.8 mL, which was the saturated water absorption capacity of the catalyst powder in this case.

[0098] (7) The amount of cyanamide required for doping was calculated according to the doping ratio of 3%, 7%, 12%, 19%, and 28%. 1 g of the catalyst powder was weighed and placed in 0.8 mL of deionized water solution, 0.8 mL of cyanamide aqueous solution with a concentration of 0.0563 g / mL, 0.1313 g / mL, 0.2250 g / mL, 0.3563 g / mL, and 0.5250 g / mL, respectively. The mixture was mixed and allowed to stand for 12 h.

[0099] (8) The material obtained in step (7) was placed in a muffle furnace and calcined at 500°C for 2h to obtain MgMnO y ,MgMnO y -N3,MgMnO y -N7,MgMnO y -N 12 ,MgMnO y -N 19 ,MgMnO y -N 28 Catalyst (cyanamide as nitrogen source).

[0100] Prepare 250 mL of acetic acid solution containing 20 mg / L, adjust the pH to 7, and then add MgMnO y ,MgMnO y -N3,MgMnO y -N7,MgMnO y -N 12 ,MgMnO y -N 19 ,MgMnO y -N 28 The catalyst (cyanamide as nitrogen source) was added in an amount of 0.1 g and then added into a columnar reactor, and ozone was introduced into the bottom of the reactor.

[0101] The ozone input was 40 mg / L (ozone concentration in the mixed gas), and the gas flow rate of ozone and oxygen was 0.5 L / min. At the beginning of the experiment, a sample was taken at 0 min, 3 min, 6 min, and 9 min for testing.

[0102] Detection method: Acetic acid was analyzed by ThermoFisher Dionex Ultimate3000 high performance liquid chromatography.

[0103] The results of pH7 water sample treatment for 9 minutes are shown in Table 5:

[0104]

[0105] Table 5

[0106] Example 6: Preparation of N-doped (cyanamide) catalyst

[0107] (1) Weigh 15.38 g of Mg(NO3)2·6H2O solid and 21.47 g of Mn(NO3)2 solution and dissolve them in 90 mL of double distilled water (the amount of Mg and Mn substances is 0.06 mol each);

[0108] (2) Add 210 mL of NaOH solution (6 mol / L) dropwise to the above solution;

[0109] (3) stirring the solution obtained in step (2) in an oil bath in a temperature-controlled magnetic stirrer at 90° C. for 2 h;

[0110] (4) cooling the solution obtained in step (3) and centrifuging to obtain a lower layer of precipitated material, washing it with water and centrifuging it again, and repeating the washing and centrifugation until the pH of the supernatant liquid at the centrifuge is less than 9;

[0111] (5) The precipitate collected in step (4) was placed in a vacuum drying oven at 80° C. and dried for 12 h;

[0112] (6) The material obtained in step (5) was ground into powder and sieved to obtain catalyst powder of 0.0385 mm-0.05 mm. Deionized water was dripped into 1 g of the catalyst powder and stirred evenly until the volume of the solution was just enough to soak the carrier and there was no excess water on the surface of the soaked catalyst. The volume of the solution was measured to be 0.8 mL, which was the saturated water absorption capacity of the catalyst powder in this case.

[0113] (7) The amount of cyanamide required for doping was calculated according to the doping ratio of 3%, 7%, 12%, 19%, and 28%. 1 g of the catalyst powder was weighed and placed in 0.8 mL of deionized water solution, 0.8 mL of cyanamide aqueous solution with a concentration of 0.0563 g / mL, 0.1313 g / mL, 0.2250 g / mL, 0.3563 g / mL, and 0.5250 g / mL, respectively. The mixture was mixed and allowed to stand for 12 h.

[0114] (8) The material obtained in step (7) was placed in a muffle furnace and calcined at 500°C for 2 h to obtain MgMnO y ,MgMnO y -N3,MgMnO y -N7,MgMnO y -N 12 ,MgMnO y -N 19 ,MgMnO y -N 28 Catalyst (cyanamide as nitrogen source).

[0115] Prepare 250 mL of acetic acid solution containing 20 mg / L, adjust the pH to 9, and then add MgMnO y ,MgMnO y -N3,MgMnO y -N7,MgMnO y -N 12 ,MgMnO y -N 19 ,MgMnO y -N 28 The catalyst (cyanamide as nitrogen source) was added in an amount of 0.1 g and then added into a columnar reactor, and ozone was introduced into the bottom of the reactor.

[0116] The ozone input was 40 mg / L (ozone concentration in the mixed gas), and the gas flow rate of ozone and oxygen was 0.5 L / min. At the beginning of the experiment, a sample was taken at 0 min, 3 min, 6 min, and 9 min for testing.

[0117] Detection method: Acetic acid was analyzed by ThermoFisher Dionex Ultimate3000 high performance liquid chromatography.

[0118] The results of pH9 water sample treatment for 9 minutes are shown in Table 6:

[0119]

[0120] Table 6

[0121] Example 7: Preparation of C (glucose)-doped catalyst

[0122] (1) Weigh 15.38 g of Mg(NO3)2·6H2O solid and 21.47 g of Mn(NO3)2 solution and dissolve them in 90 mL of double distilled water (the amount of Mg and Mn substances is 0.06 mol each);

[0123] (2) Add 210 mL of NaOH solution (6 mol / L) dropwise to the above solution;

[0124] (3) stirring the solution obtained in step (2) in an oil bath in a temperature-controlled magnetic stirrer at 90° C. for 2 h;

[0125] (4) cooling the solution obtained in step (3) and centrifuging to obtain a lower layer of precipitated material, washing it with water and centrifuging it again, and repeating the washing and centrifugation until the pH of the supernatant liquid at the centrifuge is less than 9;

[0126] (5) The precipitate collected in step (4) was placed in a vacuum drying oven at 80° C. and dried for 12 h;

[0127] (6) The material obtained in step (5) was ground into powder and sieved to obtain catalyst powder of 0.0385 mm-0.05 mm. Deionized water was dripped into 1 g of the catalyst powder and stirred evenly until the volume of the solution was just enough to soak the carrier and there was no excess water on the surface of the soaked catalyst. The volume of the solution was measured to be 0.8 mL, which was the saturated water absorption capacity of the catalyst powder in this case.

[0128] (7) The amount of glucose required for doping was calculated according to the C doping ratio of 5%, 10%, and 15%. 1 g of catalyst powder was weighed and placed in 0.8 mL of deionized water solution, 0.8 mL of glucose aqueous solution with a concentration of 0.04 g / mL, and 0.085 g / mL, respectively. The mixture was mixed and allowed to stand for 12 h.

[0129] (8) The material obtained in step (7) was placed in a muffle furnace and calcined at 500°C for 2 h to obtain MgMnO y ,MgMnO y -C5、MgMnO y -C 10 ,MgMnO y -C 15 Catalyst (glucose as carbon source).

[0130] Prepare 250 mL of acetic acid solution containing 20 mg / L, adjust the pH to 5, and then add MgMnO y -C、MgMnO y -C5、MgMnO y -C 10 ,MgMnO y -C 15The catalyst (glucose as carbon source) was added in an amount of 0.1 g and then added into a columnar reactor, and ozone was introduced into the bottom of the reactor.

[0131] The ozone input was 40 mg / L (ozone concentration in the mixed gas), and the gas flow rate of ozone and oxygen was 0.5 L / min. At the beginning of the experiment, a sample was taken at 0 min, 3 min, 6 min, and 9 min for testing.

[0132] Detection method: Acetic acid was analyzed by ThermoFisher Dionex Ultimate3000 high performance liquid chromatography.

[0133] The results of pH5 water sample treatment for 9 minutes are shown in Table 7:

[0134]

[0135] Table 7

[0136] Example 8: Preparation of C (glucose)-doped catalyst

[0137] (1) Weigh 15.38 g of Mg(NO3)2·6H2O solid and 21.47 g of Mn(NO3)2 solution and dissolve them in 90 mL of double distilled water (the amount of Mg and Mn substances is 0.06 mol each);

[0138] (2) Add 210 mL of NaOH solution (6 mol / L) dropwise to the above solution;

[0139] (3) stirring the solution obtained in step (2) in an oil bath in a temperature-controlled magnetic stirrer at 90° C. for 2 h;

[0140] (4) cooling the solution obtained in step (3) and centrifuging to obtain a lower layer of precipitated material, washing it with water and centrifuging it again, and repeating the washing and centrifugation until the pH of the supernatant liquid at the centrifuge is less than 9;

[0141] (5) The precipitate collected in step (4) was placed in a vacuum drying oven at 80° C. and dried for 12 h;

[0142] (6) The material obtained in step (5) was ground into powder and sieved to obtain catalyst powder of 0.0385 mm-0.05 mm. Deionized water was dripped into 1 g of the catalyst powder and stirred evenly until the volume of the solution was just enough to soak the carrier and there was no excess water on the surface of the soaked catalyst. The volume of the solution was measured to be 0.8 mL, which was the saturated water absorption capacity of the catalyst powder in this case.

[0143] (7) The amount of glucose required for doping was calculated according to the C doping ratio of 5%, 10%, and 15%. 1 g of catalyst powder was weighed and placed in 0.8 mL of deionized water solution, 0.8 mL of glucose aqueous solution with a concentration of 0.04 g / mL, and 0.085 g / mL, respectively. The mixture was mixed and allowed to stand for 12 h.

[0144] (8) The material obtained in step (7) was placed in a muffle furnace and calcined at 500°C for 2 h to obtain MgMnO y ,MgMnO y -C5、MgMnO y -C 10 ,MgMnO y -C 15 Catalyst (glucose as carbon source).

[0145] Prepare 250 mL of acetic acid solution containing 20 mg / L, adjust the pH to 7, and then add MgMnO y -C、MgMnO y -C5、MgMnO y -C 10 ,MgMnO y -C 15 The catalyst (glucose as carbon source) was added in an amount of 0.1 g and then added into a columnar reactor, and ozone was introduced into the bottom of the reactor.

[0146] The ozone input was 40 mg / L (ozone concentration in the mixed gas), and the gas flow rate of ozone and oxygen was 0.5 L / min. At the beginning of the experiment, a sample was taken at 0 min, 3 min, 6 min, and 9 min for testing.

[0147] Detection method: Acetic acid was analyzed by ThermoFisher Dionex Ultimate3000 high performance liquid chromatography.

[0148] The results of pH7 water sample treatment for 9 minutes are shown in Table 8:

[0149]

[0150]

[0151] Table 8

[0152] Example 9: Preparation of C (glucose)-doped catalyst

[0153] (1) Weigh 15.38 g of Mg(NO3)2·6H2O solid and 21.47 g of Mn(NO3)2 solution and dissolve them in 90 mL of double distilled water (the amount of Mg and Mn substances is 0.06 mol each);

[0154] (2) Add 210 mL of NaOH solution (6 mol / L) dropwise to the above solution;

[0155] (3) stirring the solution obtained in step (2) in an oil bath in a temperature-controlled magnetic stirrer at 90° C. for 2 h;

[0156] (4) cooling the solution obtained in step (3) and centrifuging to obtain a lower layer of precipitated material, washing it with water and centrifuging it again, and repeating the washing and centrifugation until the pH of the supernatant liquid at the centrifuge is less than 9;

[0157] (5) The precipitate collected in step (4) was placed in a vacuum drying oven at 80° C. and dried for 12 h;

[0158] (6) The material obtained in step (5) was ground into powder and sieved to obtain catalyst powder of 0.0385 mm-0.05 mm. Deionized water was dripped into 1 g of the catalyst powder and stirred evenly until the volume of the solution was just enough to soak the carrier and there was no excess water on the surface of the soaked catalyst. The volume of the solution was measured to be 0.8 mL, which was the saturated water absorption capacity of the catalyst powder in this case.

[0159] (7) The amount of glucose required for doping was calculated according to the C doping ratio of 5%, 10%, and 15%. 1 g of catalyst powder was weighed and placed in 0.8 mL of deionized water solution, 0.8 mL of glucose solution with a concentration of 0.04 g / mL, and 0.085 g / mL, respectively. The mixture was mixed and allowed to stand for 12 h.

[0160] (8) The material obtained in step (7) was placed in a muffle furnace and calcined at 500°C for 2 h to obtain MgMnO y ,MgMnO y -C5、MgMnO y -C 10 ,MgMnO y -C 15 Catalyst (glucose as carbon source).

[0161] Prepare 250 mL of acetic acid solution containing 20 mg / L, adjust the pH to 9, and then add MgMnO y -C、MgMnO y -C5、MgMnO y -C 10 ,MgMnO y -C 15 The catalyst (glucose as carbon source) was added in an amount of 0.1 g and then added into a columnar reactor, and ozone was introduced into the bottom of the reactor.

[0162] The ozone input was 40 mg / L (ozone concentration in the mixed gas), and the gas flow rate of ozone and oxygen was 0.5 L / min. At the beginning of the experiment, a sample was taken at 0 min, 3 min, 6 min, and 9 min for testing.

[0163] Detection method: Acetic acid was analyzed by ThermoFisher Dionex Ultimate3000 high performance liquid chromatography.

[0164] The results of pH9 water sample treatment for 9 minutes are shown in Table 9:

[0165]

[0166] Table 9

[0167] From the above C-doped examples (Examples 7 to 9), it can be seen that in the carbon-doped catalysts prepared with glucose as the C source, when the pH value of acetic acid is 5,7, O3 / MgMnO y -C5 has better effect than O3 / MgMnO y The catalytic efficiency of O3 / MgMnO y -C5 and O3 / MgMnO y The catalytic efficiency gap gradually becomes smaller, and even when treating acetic acid with a pH of 9, the effect of C doping on the catalytic effect is very weak. From the above N-doped embodiments (Example 1-Example 6), it can be seen that when treating acetic acid with pH of 5, 7, and 9, O3 / MgMnO y -N 12 The catalyst effect is good. With the increase of pH, O3 / MgMnO y -N 12 With O3 / MgMnO y The catalytic efficiency gap between O3 and MgMnO is gradually narrowing. y -N 12 Compared with O3 / MgMnO with cyanamide as N source y -N 12 O3 / MgMnO with glucose as C source y -C5 catalyzes ozone oxidation of acetic acid more effectively. Urea as a N source N-doped catalyst can be used in water conditions with different pH values, and has a better effect of catalyzing the oxidation of acetic acid, which can achieve the best degradation of acetic acid.

Claims

1. An N-doped manganese-magnesium binary oxide, characterized in that The N-doped manganese-magnesium binary oxide is prepared as follows: Dissolve magnesium nitrate and manganese nitrate in double distilled water, add NaOH solution dropwise, react at 70°C-120°C with stirring for 1h-3h, cool and centrifuge the reaction solution, remove the precipitate, wash with water until the pH of the washing solution is less than 9, vacuum dry, grind to obtain a carrier, add an aqueous solution of a nitrogen source dropwise, mix thoroughly, let stand for 5h-15h, and calcine at 200°C-800°C for 1h-3h to obtain the N-doped manganese-magnesium binary oxide; The molar ratio of the magnesium nitrate and the manganese nitrate is 1-2:1; the molar ratio of the NaOH contained in the NaOH solution to the total molar ratio of the magnesium nitrate and the manganese nitrate is 6-12:1; the volume of the aqueous solution of the nitrogen source is equal to the saturated water absorption capacity of the carrier; the nitrogen source contained in the aqueous solution of the nitrogen source is urea or cyanamide; the mass of the nitrogen source is 3-28% of the mass of the carrier calculated by its theoretical nitrogen content.

2. The N-doped manganese-magnesium binary oxide according to claim 1, characterized in that: The volume of the double distilled water is 0.5-1.0 L / mol based on the sum of the amounts of magnesium nitrate and manganese nitrate.

3. The N-doped manganese-magnesium binary oxide according to claim 1, characterized in that: The concentration of the NaOH solution is 4-8 mol / L.

4. The N-doped manganese-magnesium binary oxide according to claim 1, characterized in that: The molar ratio of the magnesium nitrate to the manganese nitrate is 1:

1.

5. The N-doped manganese-magnesium binary oxide according to claim 1, characterized in that: The nitrogen source contained in the aqueous solution of the nitrogen source is urea.

6. The N-doped manganese-magnesium binary oxide according to claim 1, characterized in that: The mass of the nitrogen source is 19% of the mass of the carrier based on the theoretical nitrogen content.

7. Use of the N-doped manganese-magnesium binary oxide according to claim 1 as a catalyst in catalytic ozone degradation of acetic acid in an acetic acid-containing solution, the application being: adding the N-doped manganese-magnesium binary oxide to the acetic acid-containing solution, placing the resulting mixture in a reactor, and introducing ozone from the bottom of the reactor for degradation, the pH of the acetic acid-containing solution being 5-9; the concentration of the acetic acid-containing solution being 20 mg / L, and the volume of the acetic acid-containing solution being 2.5 L / g based on the mass of the N-doped manganese-magnesium binary oxide.

8. The use according to claim 7, characterized in that: The ozone is introduced into the reactor in the form of a mixed gas of ozone and oxygen. The flow rate of the mixed gas is 0.5 L / min, and the concentration of ozone in the mixed gas is 40 mg / L.

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