Ozone oxidation catalyst and preparation method and in-situ regeneration method thereof

Abstract

The present invention belongs to the field of catalyst technology, and specifically relates to an ozone oxidation catalyst, a preparation method thereof, and an in-situ regeneration method. An ozone oxidation catalyst provided by an embodiment of the present invention, wherein the catalyst carrier is an alumina porous ball, the carrier loads carbon nitride doped with oxygen atoms, and the active components Mn and Ce are embedded in the carbon nitride in the form of single atoms, wherein the loading amount of the carbon nitride is 0.5-10%, and / or the loading amount of the Mn is 0.6-5%, and / or the loading amount of the Ce is 0.2-5%, by mass. The catalyst of the present invention can improve the mass transfer efficiency of ozone in the process of catalytic ozone oxidation, thereby improving the catalytic activity, and at the same time, the metal atoms are anchored by a two-dimensional carbon nitride material, so that the catalyst obtains a higher stability.

Description

Technical Field

[0001] The present invention belongs to the technical field of catalysts, and specifically relates to an ozone oxidation catalyst, and in particular, also relates to a method for preparing the ozone oxidation catalyst, and further, also relates to an in-situ regeneration method of the ozone oxidation catalyst. Background Art

[0002] In the deep treatment of industrial wastewater in my country, ozone oxidation is one of the most widely used technologies. However, the mineralization efficiency of some organic pollutants in the ozone oxidation process alone is not high, and more toxic substances may be produced during the oxidation process. The catalytic ozone oxidation process increases the concentration of hydroxyl radicals in the reaction system by adding catalysts, thereby increasing the mineralization rate of organic matter and ensuring the ecological safety of the effluent. Therefore, the catalytic ozone oxidation process is becoming more and more promising and attractive.

[0003] According to the type of catalyst, catalytic ozone oxidation can be divided into homogeneous catalytic ozone oxidation and heterogeneous catalytic ozone oxidation. In the homogeneous catalytic ozone oxidation process, dissolved transition metal ions are used as catalysts, while in the heterogeneous catalytic ozone oxidation process, solid catalysts are used. Since most transition metal ions are harmful to the environment and need to be separated from the treated wastewater, and the concentration of transition metal ions in water is very low, separation is a challenging task, which limits the application of homogeneous catalytic ozone oxidation. Solid catalysts are easy to separate and can maintain catalytic activity for a long time, which makes heterogeneous catalytic ozone oxidation technology widely studied.

[0004] Over the past 20 years, scholars have studied a large number of new and efficient heterogeneous catalysts, which mainly include four categories: metal oxide catalysts (MnO 2 、TiO 2 、Al 2 O 3 、CeO 2 etc.), supported metal or metal oxide catalysts (Cu / Al 2 O 3 、Cu / TiO 2 、Ru / CeO 2 、Co / SiO 2 、TiO 2 / Al 2 O 3 , Fe 2 O 3 / Al 2 O 3 、CoOx / Al 2 O 3 、MnOx / ZrO 2Among these catalysts, supported catalysts are considered to be the most promising catalysts for industrial applications because they have high specific surface area, good mechanical strength, excellent catalytic activity and stability.

[0005] However, at present, most of the research on catalytic ozone oxidation uses nano / micron-sized catalyst powders. This ultra-fine property greatly limits the practical application of the catalyst. Therefore, it is necessary to study and improve the catalytic ozone oxidation catalyst. Summary of the invention

[0006] The present invention is based on the inventor's discovery and understanding of the following facts and problems:

[0007] Supported metal catalysts are prepared by calcining after impregnation with a precursor salt solution. A large number of active components grow into large grains in the pores of the carrier, reducing the pore size and pore volume of the carrier, and hindering the diffusion of ozone into the pores to react with the active components. The ozone concentration in the liquid phase is very low, the liquid-solid concentration gradient is small, and the mass transfer resistance is large, which leads to low utilization of active components in the pores. In addition, the continuous use of metal catalysts will cause metal ion leaching, resulting in the loss of active components, which also reduces the utilization of active components.

[0008] Single atom catalysts (SACs) have highly uniform and fully exposed active sites, and each atom can participate in the catalytic reaction, thereby achieving higher catalytic performance; in addition, through a strong metal-substrate interaction, the metal single atoms are firmly anchored on the substrate, improving stability and reducing metal dissolution rate. Although there have been many studies on SACs, most of the reported SACs are in powder form, and granulation may cause most of the metal atoms to be encapsulated in the catalyst body. Because the metal active components are very easy to grow and aggregate during the calcination process, directly loading Mn and Ce on Al in the form of single atoms is not a good idea. 2 O 3 There are huge challenges on the surface.

[0009] With the help of graphite carbon nitride (gC 3 N 4 ) has the function of anchoring metal atoms and is expected to prepare porous pellet SACs, gC 3 N 4 It has a graphene-like two-dimensional structure, high chemical stability, and can promote the uniform dispersion of active components. 3 N 4 Their activity in catalytic ozonation is limited by poor electron transfer ability and a lack of surface oxygen-containing groups, which needs to be tuned through surface engineering.

[0010] The present invention aims to solve at least one of the technical problems in the related art to a certain extent. To this end, an embodiment of the present invention proposes an ozone oxidation catalyst, which uses alumina porous balls as carriers and uses two-dimensional carbon nitride materials to anchor metal atoms, so that Mn and Ce can form a flat single atomic layer on the surface of the alumina porous balls and the inner surface of the pores, so that the catalyst can improve the mass transfer efficiency of ozone and thus improve the catalytic activity during the catalytic ozone oxidation process, and at the same time uses two-dimensional carbon nitride materials to anchor metal atoms, so that the catalyst has a higher stability.

[0011] In the ozone oxidation catalyst of the embodiment of the present invention, the catalyst carrier is a porous alumina ball, the carrier carries carbon nitride doped with oxygen atoms, and the active components Mn and Ce are embedded in the carbon nitride in the form of single atoms.

[0012] The advantages and technical effects brought by the ozone oxidation catalyst of the embodiment of the present invention are as follows: 1. In the embodiment of the present invention, the active components Mn and Ce can form a flat single atomic layer on the surface of the alumina porous ball and the inner surface of the pores with the help of carbon nitride, which can improve the mass transfer efficiency of ozone and thus improve the catalytic activity during the catalytic ozone oxidation process; 2. In the embodiment of the present invention, a two-dimensional carbon nitride material is used to anchor metal atoms in the catalyst, so that the catalyst has a higher stability; 3. In the embodiment of the present invention, a carbon nitride material doped with oxygen atoms is used to anchor metal atoms. Since the atomic radius of O atoms is smaller than that of N atoms, and O atoms have one more valence electron than N atoms, O atoms are doped into carbon nitride gC 3 N 4 You can adjust gC 3 N 4 The structural and electronic properties of gC 3 N 4 More defects, oxygen-containing groups may be located on these defects. In this case, the widely incorporated oxygen-containing groups can serve as active sites for catalytic ozonation, thereby improving the activity of the catalyst; 4. The catalyst of the embodiment of the present invention is suitable for deep treatment of organic wastewater generated in fine chemicals, landfill leachate, pharmaceuticals, organic pesticides, coal chemical industry, petrochemical industry, printing and dyeing and other industries, and has broad application prospects.

[0013] In some embodiments, in the catalyst, the loading amount of the carbon nitride is 0.5-10%, and / or the loading amount of the Mn is 0.6-5%, and / or the loading amount of the Ce is 0.2-5%, by mass; the diameter of the alumina porous sphere is 3-5 mm.

[0014] In some embodiments, the carbon nitride is graphite carbon nitride, and the doping amount of oxygen atoms in the carbon nitride is 1.5%-5.2wt%.

[0015] The present invention also provides a method for preparing an ozone oxidation catalyst, comprising the following steps:

[0016] (1) adding a precursor, a manganese salt, a cerium salt, and an auxiliary agent to water according to a designed ratio, heating to dissolve, and drying to obtain a solid mixture, wherein the precursor comprises at least one of dicyandiamide, melamine, or urea, and the auxiliary agent comprises at least one of oxalic acid or ascorbic acid;

[0017] (2) subjecting the solid mixture obtained in step (1) to pyrolysis to obtain gC anchoring Mn and Ce bimetallic atoms; 3 N 4 , denoted as MnCe-CNO;

[0018] (3) Grinding the MnCe-CNO obtained in step (2) and heating the porous alumina balls under an inert atmosphere to obtain a catalyst MnCe-CNO / Al 2 O 3 .

[0019] The advantages and technical effects brought by the preparation method of the ozone oxidation catalyst of the embodiment of the present invention are as follows: 1. In the method of the embodiment of the present invention, dicyandiamide, melamine or urea is used as a precursor material to prepare a two-dimensional carbon nitride material, and the precursor material is mixed with a manganese salt and a cerium salt for pyrolysis treatment to anchor the metal atoms Mn and Ce in the form of a single atom on the two-dimensional carbon nitride material, and then the carbon nitride material is composited with a carrier to achieve the formation of a single atomic layer of metal atoms Mn and Ce on the alumina porous ball carrier; 2. In the preparation method of the embodiment of the present invention, by adding an auxiliary agent oxalic acid or ascorbic acid to the precursor, the two-dimensional carbon nitride material is doped with oxygen atoms, and the doping of oxygen atoms can increase the carbon nitride gC 3 N 4 The number of oxygen-containing functional groups and nitrogen vacancies on the surface, mainly CO, C=O and / or NO bonds, can adjust the gC 3 N 4 configuration and physical and chemical properties, and at the same time generate new active sites, thereby improving the performance of the catalyst in catalyzing ozonation; 3. The preparation method of the embodiment of the present invention is simple and efficient, and no waste is generated, which is suitable for promotion and application in industrial production.

[0020] In some embodiments, in step (1), the molar ratio of the precursor to the manganese salt is 100-400:1, and the molar ratio of the precursor to the auxiliary agent is 3-7:1; the molar ratio of the manganese salt to the cerium salt is (1-10):1; the manganese salt includes manganese acetate or manganese nitrate, and the cerium salt includes cerium acetate or cerium nitrate.

[0021] In some embodiments, in step (2), the heating rate of the pyrolysis treatment is 1-5°C / min, the temperature is raised to 500-600°C, and maintained for 1-5h.

[0022] In some embodiments, in step (3), the mass ratio of the MnCe-CNO to the porous alumina spheres is (0.02-2):1.

[0023] In some embodiments, in step (3), the inert gas is N 2 and at least one of Ar.

[0024] In some embodiments, in step (3), the temperature of the heating treatment is 550-900° C., and the treatment time is 2-6 hours.

[0025] The embodiment of the present invention further provides an in-situ regeneration method of an ozone oxidation catalyst, wherein the in-situ regeneration method is to perform air-water backwashing on the catalyst.

[0026] The advantages and technical effects brought by the in-situ regeneration method of the ozone oxidation catalyst in the embodiment of the present invention are as follows: 1. The method in the embodiment of the present invention can regenerate the catalyst in situ, thereby increasing the service life of the catalyst, thereby reducing production costs and reducing waste of resources; 2. The method in the embodiment of the present invention is simple and easy to operate, and the catalyst can be regenerated by only backwashing, thereby improving production efficiency and facilitating promotion and application in industrial production.

[0027] In some embodiments, the backwash water used for backwashing is a citric acid aqueous solution with a mass percentage of 1-2%. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic diagram of ozone mass transfer and catalytic mechanism of the ozone oxidation catalyst according to an embodiment of the present invention. DETAILED DESCRIPTION

[0029] Embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to be used to explain the present invention, but should not be understood as limiting the present invention.

[0030] An ozone oxidation catalyst provided by an embodiment of the present invention comprises a catalyst carrier which is an alumina porous sphere, the carrier carries carbon nitride doped with oxygen atoms, and active components Mn and Ce are embedded in the carbon nitride in the form of single atoms.

[0031] In the ozone oxidation catalyst of the embodiment of the present invention, the active components Mn and Ce can form a flat single atomic layer on the surface of the alumina porous ball and the inner surface of the pores with the help of carbon nitride, which can improve the mass transfer efficiency of ozone and thus improve the catalytic activity during the catalytic ozone oxidation process; in the embodiment of the present invention, a two-dimensional carbon nitride material is used to anchor metal atoms in the catalyst, so that the catalyst has a higher stability; in the embodiment of the present invention, a carbon nitride material doped with oxygen atoms is used to anchor metal atoms. Since the atomic radius of O atoms is smaller than that of N atoms and the valence electrons of O atoms are one more than those of N atoms, O atoms are doped into carbon nitride gC 3 N 4 You can adjust gC 3 N 4 The structural and electronic properties of gC 3 N 4 There are more defects, and the oxygen-containing groups may be located on these defects. In this case, the widely incorporated oxygen-containing groups can serve as active sites for catalytic ozonation, thereby improving the activity of the catalyst. The catalyst of the embodiment of the present invention is suitable for deep treatment of organic wastewater generated by fine chemicals, landfill leachate, pharmaceuticals, organic pesticides, coal chemical industry, petrochemical industry, printing and dyeing and other industries, and has broad application prospects.

[0032] In some embodiments, in the catalyst, the loading amount of the carbon nitride is 0.5-10%, preferably 1-5%, more preferably 2-4%, the loading amount of the Mn is 0.6-5%, preferably 0.6-4%, more preferably 0.6-2%, and the loading amount of the Ce is 0.2-5%, preferably 0.2-4%, more preferably 0.2-1.2%, by mass.

[0033] In the embodiment of the present invention, the loading amount of carbon nitride and metal in the catalyst is further optimized, and the performance of the catalyst is further improved. If the carbon nitride loading amount is too much, the specific surface area of ​​the porous alumina sphere is limited, and excessive loading will cause shedding. If the carbon nitride loading amount is too little, it cannot provide enough single-atom anchoring substrate for Mn and Ce; if the active components Mn and Ce are loaded too little, the catalytic activity of the catalyst is insufficient. If the active components Mn and Ce are loaded too much, Mn and Ce will agglomerate, and the active sites cannot be fully exposed, affecting the activity of the catalyst.

[0034] In some embodiments, the diameter of the alumina porous sphere is 3-5 mm. In the embodiments of the present invention, alumina porous spheres with larger diameters are used as carriers to obtain large-particle catalysts, thereby avoiding the need to prepare nano-scale catalysts in the prior art. Nano-scale catalysts can only be prepared in laboratories and cannot be industrially applied. The embodiments of the present invention obtain large-particle supported catalysts, thereby solving the problem that nano-powder catalysts are difficult to industrially apply, and are suitable for popularization and application.

[0035] In some embodiments, the carbon nitride is graphite carbon nitride, and the doping amount of oxygen atoms in the carbon nitride is 1.5%-5.2wt%. In the embodiments of the present invention, the doping amount of oxygen atoms in the carbon nitride refers to the mass percentage of oxygen atoms in the carbon nitride material. In the embodiments of the present invention, the doping amount of oxygen atoms in the carbon nitride is further preferred. If the doping amount of oxygen atoms is too little, the number of active sites in the carbon nitride will be insufficient, which is not conducive to improving the activity of the catalyst. If the doping amount of oxygen atoms is too much, it may change the carbon nitride gC 3 N 4 The structure is not conducive to single-atom anchoring.

[0036] like Figure 1 As shown, the ozone mass transfer and catalytic mechanism of the ozone oxidation catalyst of the embodiment of the present invention is:

[0037] The delocalized electrons on the carbon nitride basal plane favor Ce 3+ The formation of Ce 3+ / Ce 4+ The redox reaction on the catalyst surface promotes the catalytic decomposition of ozone into OH. 3+ / Ce 3+ ——Mn 4+ / Ce 4+ ——Mn 3+ / Ce 3+ The cyclic reaction generates oxygen vacancies on the catalyst surface, which enhances the oxygen adsorption capacity of the catalyst surface. In order to maintain electrostatic balance, lattice oxygen transfers Mn 4+ / Ce 4+ Reduction of Mn 3+ / Ce 3 , and oxygen vacancies can be supplemented by ozone. In this balanced cycle reaction, the catalytic decomposition of ozone into free radicals with high oxidizing ability is promoted, achieving efficient removal of organic pollutants. In addition, the active sites on the catalyst surface catalyze the decomposition of ozone into active oxygen species such as hydroxyl radicals through free radical chain reactions, which can non-selectively attack difficult-to-degrade organic matter.

[0038] The present invention also provides a method for preparing an ozone oxidation catalyst, comprising the following steps:

[0039] (1) adding a precursor, a manganese salt, a cerium salt, and an auxiliary agent into high-purity water according to a designed ratio, heating to dissolve, and drying to obtain a solid mixture, wherein the precursor includes at least one of dicyandiamide, melamine, or urea, and the auxiliary agent includes at least one of oxalic acid or ascorbic acid;

[0040] (2) subjecting the solid mixture obtained in step (1) to pyrolysis to obtain gC anchoring Mn and Ce bimetallic atoms; 3 N 4 , denoted as MnCe-CNO;

[0041] (3) grinding the MnCe-CNO obtained in step (2) and heating it with alumina porous balls under an inert atmosphere to obtain a catalyst MnCe-CNO / Al 2 O 3 .

[0042] The preparation method of the ozone oxidation catalyst of the embodiment of the present invention adopts dicyandiamide, melamine or urea as a precursor material to prepare a two-dimensional carbon nitride material, and at the same time, the precursor material is mixed with a manganese salt and a cerium salt for pyrolysis treatment, and the metal atoms Mn and Ce are anchored on the two-dimensional carbon nitride material in a single-atom form, and then the carbon nitride material is composited with a carrier, so that the metal atoms Mn and Ce form a single atomic layer on the alumina porous ball carrier; in the embodiment of the present invention, by adding an auxiliary agent oxalic acid or ascorbic acid to the precursor, the two-dimensional carbon nitride material is doped with oxygen atoms, and the doping of oxygen atoms can increase the carbon nitride gC 3 N 4 The number of oxygen-containing functional groups and nitrogen vacancies on the surface, mainly CO, C=O and / or NO bonds, can adjust the gC 3 N 4 The configuration and physical and chemical properties of the catalyst are improved, and new active sites are generated, thereby improving the performance of the catalyst in catalyzing ozonation. The preparation method is simple and efficient, and no waste is generated, which is suitable for promotion and application in industrial production.

[0043] In some embodiments, preferably, in step (1), the molar ratio of the precursor to the manganese salt is 100-400:1, the molar ratio of the precursor to the auxiliary agent is 3-7:1; the molar ratio of the manganese salt to the cerium salt is (1-10): 1. Further preferably, the manganese salt includes manganese acetate or manganese nitrate, and the cerium salt includes cerium acetate or cerium nitrate.

[0044] In the embodiment of the present invention, the molar ratio of the precursor and the auxiliary agent is limited, which is beneficial to doping the carbon nitride material with an appropriate amount of oxygen atoms. At the same time, the molar ratio of the precursor, manganese salt and cerium salt is limited, which is beneficial to anchoring the metal atoms on the two-dimensional carbon nitride material, avoiding the agglomeration of metal atoms on the carrier caused by directly loading metal atoms on the carrier, thereby improving the stability of the catalyst.

[0045] In some embodiments, preferably, in the step (2), the heating rate of the pyrolysis treatment is 1-5°C / min, the temperature is raised to 500-600°C, and maintained for 1-5h.

[0046] In the embodiments of the present invention, the conditions for the pyrolysis treatment are optimized, which is conducive to the stable anchoring of metal atoms on the two-dimensional carbon nitride material, so that the catalyst has better stability and its service life is increased.

[0047] In some embodiments, preferably, in step (3), the mass ratio of the MnCe-CNO to the alumina porous sphere is (0.02-2):1. Further preferably, in step (3), the inert gas is N 2 and Ar; the heating treatment temperature is 550-900°C, and the treatment time is 2-6h.

[0048] In the embodiment of the present invention, the mass ratio of MnCe-CNO to alumina porous spheres is limited, which is beneficial to the uniform distribution of metal atoms on the surface of the carrier as a single atomic layer, and the metal atoms do not aggregate, thereby improving the catalytic activity of the catalyst; if the MnCe-CNO content is too low, the catalytic activity is insufficient, and the catalyst cannot effectively exert its catalytic effect; if the MnCe-CNO content is too high, it may cause the pores of the alumina porous spheres to be blocked or most of the active sites to be wrapped and not fully exposed.

[0049] The embodiment of the present invention further provides an in-situ regeneration method of an ozone oxidation catalyst, wherein the in-situ regeneration method regenerates the catalyst in-situ by backwashing with air and water.

[0050] The in-situ regeneration method of the ozone oxidation catalyst of the embodiment of the present invention can regenerate the catalyst in situ, thereby increasing the service life of the catalyst, thereby reducing production costs and reducing waste of resources; the method is simple and easy to operate, and the catalyst can be regenerated by only backwashing, thereby improving production efficiency and facilitating promotion and application in industrial production.

[0051] In some embodiments, preferably, the backwash water used for the backwashing is a citric acid aqueous solution with a mass percentage of 1% to 2%.

[0052] The present invention is described in detail below in conjunction with specific embodiments.

[0053] 1. Preparation of Catalyst

[0054] Example 1

[0055] (1) adding 24 mol of dicyandiamide, 0.08 mol of manganese acetate, 0.02 mol of cerium acetate and 5 mol of oxalic acid (i.e., the molar ratio of the precursor dicyandiamide to the manganese salt manganese acetate is 300:1, the molar ratio of the precursor dicyandiamide to the auxiliary oxalic acid is 4.8:1, and the molar ratio of the manganese salt manganese acetate to the cerium salt cerium acetate is 4:1) into high-purity water, heating to 60° C. and stirring until dissolved, and drying at 103.5° C. to obtain a solid mixture;

[0056] (2) The solid mixture was ground, heated to 550°C at a heating rate of 2°C / min, and pyrolyzed for 3 h to obtain gC anchoring Mn and Ce bimetallic atoms. 3 N 4 , denoted as MnCe-CNO;

[0057] (3) 0.15 parts by weight of MnCe-CNO and 1 part by weight of porous alumina balls were mixed in N 2 The temperature was raised to 600 °C under the atmosphere and heated for 4 h to obtain the catalyst MnCe-CNO / Al 2 O 3 .

[0058] In the catalyst prepared in this embodiment, the loading amount of the two-dimensional carbon nitride material is 4.0 wt %, the loading amount of Mn is 2.0 wt %, the loading amount of Ce is 1.2 wt %, and the doping amount of oxygen atoms in the carbon nitride material is 2.0 wt %.

[0059] Example 2

[0060] The method is the same as that of Example 1, except that the precursor material used is melamine.

[0061] Example 3

[0062] The method is the same as that of Example 1, except that the precursor material used is urea.

[0063] Example 4

[0064] The method is the same as that of Example 1, except that the amounts of each substance used are different.

[0065] In the catalyst prepared in this embodiment, the loading amount of the two-dimensional carbon nitride material is 2.1 wt %, the loading amount of Mn is 0.6 wt %, the loading amount of Ce is 0.2 wt %, and the doping amount of oxygen atoms in the carbon nitride material is 1.5 wt %.

[0066] Example 5

[0067] The method is the same as that of Example 1, except that the amounts of each substance used are different.

[0068] In the catalyst prepared in this embodiment, the loading amount of the two-dimensional carbon nitride material is 3 wt %, the loading amount of Mn is 4.0 wt %, the loading amount of Ce is 4.0 wt %, and the doping amount of oxygen atoms in the carbon nitride material is 2.5 wt %.

[0069] Comparative Example 1 Preparation of Nanocatalyst MnCe-O / γ-Al 2 O 3

[0070] Preparation method: The nano-alumina balls were immersed in a mixed solution of manganese acetate and cerium acetate for 12 hours, then dried for 8 hours, and calcined at 450°C for 4 hours to obtain the nano-catalyst MnCe-O / γ-Al 2 O 3 .

[0071] In the catalyst prepared in Comparative Example 1, the Mn loading amount is 0.6%, and the Ce loading amount is 0.2%.

[0072] Comparative Example 2 Preparation of Nanocatalyst MnCe-O / γ-Al 2 O 3

[0073] The preparation method is the same as that of Comparative Example 1, except that in the catalyst prepared in Comparative Example 2, the Mn loading amount is 2.0%, and the Ce loading amount is 1.2%.

[0074] Comparative Example 3

[0075] The preparation method is the same as that of Example 1, except that oxalic acid is not added in step (1), that is, the obtained two-dimensional carbon nitride material is not doped with oxygen atoms, and the obtained catalyst MnCe-CN / Al 2 O 3 .

[0076] In the catalyst prepared in Comparative Example 3, the loading amount of the two-dimensional carbon nitride material was 4.0 wt %, the loading amount of Mn was 2.0%, and the loading amount of Ce was 1.2%.

[0077] 2. Catalyst performance test

[0078] The catalysts prepared in the examples and comparative examples were subjected to application tests to test the performance of each catalyst, as shown in the following.

[0079] Experimental Example 1

[0080] Catalyst catalytic ozone oxidation was used to treat nitrobenzene simulated wastewater. The catalyst dosage was 20g / L, the ozone dosage was 50mg / L, the nitrobenzene concentration in the wastewater was 320ug / L, and it was operated continuously for 30 days. The test results are shown in Table 1.

[0081] Table 1

[0082]

[0083] Note: Comparative Example 4 is to perform ozone oxidation treatment alone without adding a catalyst.

[0084] Experimental Example 2

[0085] The catalyst was used to treat the secondary biochemical effluent of a fine chemical wastewater. The COD concentration in the wastewater was 130 mg / L, the salt content was 17000 mg / L, the catalyst dosage was 100 g / L, the ozone dosage was 150 mg / L, and it was continuously operated for 30 days at a scale of 400 L / h. The test results are shown in Table 2.

[0086] Table 2

[0087]

[0088] Note: Comparative Example 4 is to perform ozone oxidation treatment alone without adding a catalyst.

[0089] Experimental Example 3

[0090] Catalyst-catalyzed ozone oxidation was used to degrade atenolol in water (the initial concentration of atenolol in pure water was 10 mg / L). The ozone dosage was 14 mg / L and the catalyst dosage was 20 g / L. After 30 days of operation, the test results are shown in Table 3.

[0091] Table 3

[0092]

[0093] Note: Comparative Example 4 is to perform ozone oxidation treatment alone without adding a catalyst.

[0094] Experimental Example 4

[0095] When the secondary biochemical effluent of coal chemical wastewater (COD about 440 mg / L) was treated by catalyst catalytic ozone oxidation, the catalyst dosage was 180 g / L, the ozone dosage was 180 mg / L, and it was run for 30 days. The test results are shown in Table 4.

[0096] Table 4

[0097]

[0098] Note: Comparative Example 4 is to perform ozone oxidation treatment alone without adding a catalyst.

[0099] It can be seen from the above Experimental Examples 1-4 that the catalyst of the embodiment of the present invention has a good treatment effect on various sewage, especially in Experimental Example 2, it still has a good COD removal effect on the difficult-to-treat fine chemical wastewater with high salt content and COD below 150 mg / L, and the removal rate can reach 66%.

[0100] 3. In-situ regeneration of catalyst

[0101] The catalyst of Example 1 tested in Experimental Example 4 was regenerated by backwashing with a 1 wt % citric acid aqueous solution, first air washing for 2 minutes, then air-water mixed washing for 10 minutes, and finally water washing for 8 minutes, with a total backwashing time of 20 minutes, to obtain a regenerated catalyst.

[0102] The regenerated catalyst was further used in the test of Experimental Example 4, and the COD removal rate was 62.8% after 30 days of operation.

[0103] In the present invention, the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" etc. mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the described specific features, structures, materials or characteristics may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0104] Although the above embodiments have been shown and described, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations on the present invention. Changes, modifications, substitutions and variations of the above embodiments by those of ordinary skill in the art are all within the scope of protection of the present invention.

Claims

1. A method for preparing an ozone oxidation catalyst, It is characterized in that The following steps are involved: (1) adding a precursor, a manganese salt, a cerium salt and an auxiliary agent to water according to a designed ratio, heating to dissolve, and drying to obtain a solid mixture, wherein the precursor comprises at least one of dicyandiamide, melamine or urea, the auxiliary agent comprises at least one of oxalic acid or ascorbic acid, the molar ratio of the precursor to the manganese salt is (100-400):1, the molar ratio of the precursor to the auxiliary agent is (3-7):1, and the molar ratio of the manganese salt to the cerium salt is (1-10):1; (2) The solid mixture obtained in step (1) is subjected to pyrolysis treatment to obtain gC anchoring Mn and Ce bimetallic atoms. 3 N 4 , denoted as MnCe-CNO; (3) The MnCe-CNO and alumina porous balls obtained in step (2) are heated under an inert atmosphere to obtain a catalyst MnCe-CNO / Al 2 O 3 , wherein the mass ratio of the MnCe-CNO to the porous alumina sphere is (0.02~2):1; the carrier of the prepared catalyst is porous alumina sphere, the carrier carries carbon nitride doped with oxygen atoms, and the active components Mn and Ce are embedded in the carbon nitride in the form of single atoms.

2. The method for preparing the ozone oxidation catalyst according to claim 1, It is characterized in that In the catalyst, the loading amount of the carbon nitride is 0.5-10%, and / or the loading amount of the Mn is 0.6-5%, and / or the loading amount of the Ce is 0.2-5%, by mass; the diameter of the porous alumina sphere is 3-5 mm.

3. The method for preparing the ozone oxidation catalyst according to claim 1, It is characterized in that The carbon nitride is graphite carbon nitride, and the doping amount of oxygen atoms in the carbon nitride is 1.5%-5.2wt%.

4. The method for preparing the ozone oxidation catalyst according to claim 1, It is characterized in that In the step (1), the manganese salt includes manganese acetate or manganese nitrate, and the cerium salt includes cerium acetate or cerium nitrate.

5. The method for preparing the ozone oxidation catalyst according to claim 1, It is characterized in that In the step (2), the heating rate of the pyrolysis treatment is 1-5 °C / min, the temperature is raised to 500-600 °C, and maintained for 1-5 hours.

6. The method for preparing the ozone oxidation catalyst according to claim 1, It is characterized in that In the step (3), the temperature of the heating treatment is 550-900°C, and the treatment time is 2-6 hours.

7. An in-situ regeneration method for an ozone oxidation catalyst prepared by the method according to any one of claims 1 to 6, It is characterized in that The in-situ regeneration method is to perform air-water backwashing on the catalyst.

8. The in-situ regeneration method of the ozone oxidation catalyst according to claim 7, It is characterized in that The backwash water used in the backwashing is a citric acid aqueous solution with a mass percentage of 1-2%.

Images