Preparation method of a double-carrier supported metal oxide catalyst and application thereof

Abstract

The application belongs to the field of catalysts, and discloses a preparation method of a double-carrier supported metal oxide catalyst and application thereof. The preparation method comprises the following steps: firstly, loading the metal oxide on a first carrier, uniformly dispersing the metal oxide on the first carrier by adopting a constant-temperature immersion and steam drying method at 80 DEG C, drying at 100 DEG C, calcining at 500 DEG C, and grinding to obtain a powder, and then wrapping the powder on a second carrier to prepare the double-carrier catalyst. The preparation method is simple and efficient, the active components on the surface of the catalyst are more uniform, the amount of the metal oxide is small, and the carrier is cheap and easy to obtain. The catalyst has good ozone oxidation effect, can be repeatedly used for multiple times, can be used for treating various organic pollutant wastewater, and is suitable for large-scale application.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of catalysts, and relates to a preparation method of a double-carrier supported metal oxide catalyst and application thereof. The present application relates to a preparation method of a double-carrier supported metal oxide catalyst and application thereof in organic wastewater treatment. The present application relates to a preparation method of a double-carrier supported metal oxide catalyst and application thereof in organic wastewater treatment. BACKGROUND

[0002] Wastewater contains a large amount of heterocyclic compounds, polycyclic aromatic hydrocarbon compounds, phenols, halogenated hydrocarbons and other highly toxic and refractory organic pollutants. These pollutants are easily enriched in the environment and organisms, and can cause biological teratogenicity and carcinogenicity.

[0003] Coagulation, sedimentation, adsorption and membrane separation can be used for treating organic pollutants in wastewater. These methods are simple to operate and have low treatment cost, but they are non-destructive for treating refractory pollutants and can easily cause secondary pollution. Advanced oxidation processes using light, electricity, H2O2 and ozone to produce active oxygen species have a wide range of applications, are destructive for treating refractory organic pollutants, and can completely degrade them into inorganic substances, CO2 and H2O and other small molecules. However, there are still some problems in the current advanced oxidation technology. Photocatalytic oxidation has low treatment capacity, complex device and high cost. In electrocatalytic oxidation, the cathode does not participate in the degradation reaction, resulting in energy waste. The Fenton-like method using H2O2 as an oxidant produces iron sludge, causing secondary pollution. Catalytic ozone oxidation does not require additional complex photoelectric generation devices, has strong oxidation capacity, does not pollute the environment, has a wide pH range, and is more efficient and complete in treating wastewater, and has become an important method for treating refractory organic wastewater. The addition of a catalyst in ozone oxidation can promote the generation of more strong oxidizing hydroxyl radicals from dissolved ozone in water, thereby more completely degrading organic pollutants without causing other pollution.

[0004] Most of the catalysts currently used for the catalytic ozonation of organic compounds are supported metal oxides, which are generally prepared by loading metal oxides (MnO2, CeO2, MgO, NiO, Co3O4, CuO, ZnO, Fe2O3, La2O3, etc.) on porous materials (ceramsite, Al2O3, SiO2, molecular sieve, sepiolite, montmorillonite, carbon material, etc.) as carriers by impregnation, precipitation, etc. Patent CN109772327 is a supported ozone oxidation catalyst with Al2O3 as the carrier, prepared by a coprecipitation method with Fe2O3, CuO, ZnO, Co2O3, NiO, etc. transition metal oxides and / or CeO2, La2O3, etc. rare earth metal oxides as active components. Its preparation method includes five processes of precipitation, peptization, balling, washing, and calcination. Patent CN105439370 selects modified ceramsite, Al2O3, molecular sieve, columnar activated carbon, or granular activated carbon as the carrier, and loads 3.0-5.0 wt.% of one or more than two transition metal elements of Cu, Fe, Mn, Ce, or Co by impregnation. Patent CN114160184 synthesizes Ag nanoparticles with uniform size in advance. Then, CeO2 is loaded on the molecular sieve by impregnation to obtain CeO2 / molecular sieve. Finally, the Ag nanoparticles are dispersed on the CeO2 / molecular sieve by particle adsorption. Patent CN113620407 is a single-atom catalyst prepared by loading transition metals in the form of single atoms on a carrier, and then coating the single-atom catalyst on a silicon carbide honeycomb ceramic plate for ozone oxidation of wastewater. The transition metal is one or any combination of Ag, Cu, Fe, and Mn. The carrier is modified porous active nanocarbon. Patent CN112408578 is a method for preparing a catalytic ozone oxidation honeycomb body filler. The method includes the following steps: soaking molecular sieve powder in an organic acid solution and calcining to obtain modified molecular sieve powder; dispersing the modified molecular sieve powder and a modified agent powder in a binder solution to convert into a cement, vacuum stirring until the gas in the cement is removed to obtain a kneaded cement; transferring the kneaded cement to an extruder to prepare a blank body through a honeycomb body mold; calcining the blank body to obtain a molecular sieve honeycomb body; and immersing the molecular sieve honeycomb body in a nitrate solution of a transition metal element, calcining after impregnation to obtain a catalytic ozone oxidation honeycomb body filler. In addition, the powder of the porous carrier and the metal oxide can also be mixed directly, and then combined with a binder to obtain the catalyst after granulation. Patent CN105381804 uses manganese sand filter material or soft manganese ore as raw material, adds a binder, a peptizing agent, and a pore-expanding agent, and goes through a series of processes of grinding-mixing-kneading-extrusion molding-drying and calcination to form an ozone oxidation catalyst.

[0005] The preparation method of the above-mentioned catalyst is complex, and the active component in the catalyst is not fully utilized, which increases the cost of treating wastewater. Therefore, it is necessary to develop a simple, efficient and widely applicable preparation method of ozone oxidation catalyst. SUMMARY

[0006] In order to overcome the shortcomings of the prior art, the present application provides a preparation method of a double-carrier supported metal oxide catalyst and its application. The preparation method first loads the metal oxide on the first carrier, uniformly disperses the metal oxide on the first carrier by constant temperature immersion and evaporation drying at 80℃, dries at 100℃, calcines at 500℃, and grinds to obtain a powder, then wraps the powder on the second carrier to prepare a double-carrier catalyst. The preparation method of the present application is simple and efficient, the active component on the surface of the catalyst is more uniform, the amount of metal oxide is less, and the carrier is cheap and easy to obtain. The catalyst has good ozone oxidation effect, can be repeatedly used, can treat various organic pollutant wastewater, and is suitable for large-scale application.

[0007] The above-mentioned object of the present application is achieved by the following technical solutions:

[0008] A preparation method of a double-carrier supported metal oxide catalyst, the specific steps are as follows:

[0009] S1. Preparation of molecular sieve loaded metal oxide, take a certain mass ratio of metal nitrate and first carrier molecular sieve, add deionized water according to the mass ratio of first carrier molecular sieve to deionized water of 1:15, mix and stir, heat at 80℃ and slowly stir to paste, dry at 100℃ for 4h, calcine at 500℃ for 4h, and grind for standby. Get the powder of molecular sieve loaded metal oxide.

[0010] S2. The powder prepared in S1 is wrapped in the second carrier. The second carrier of different particle size specifications is washed with water and dried for 2h. Take 10 times the mass of the second carrier of the powder prepared in S1, immerse in silica sol for 10min, then pour into a round pot granulator, sprinkle the powder of the molecular sieve loaded metal oxide prepared in step S1, roll granulation, sieve to remove the powder, dry at 100℃ for 1h, then lay flat in a shaking bed, evenly spray with silica sol, then dry at 100℃ for 1h, calcine at 500℃ for 4h, and repeat the above operation 1-4 times to obtain the catalyst.

[0011] The first carrier molecular sieve is any one of Y, ZSM-5, β, MOR, preferably NaY and HZSM-5, which can be purchased or prepared by oneself.

[0012] The metal oxide in the loaded metal oxide is any one or two or more of MnO2, CeO2, MgO, NiO, Co3O4, CuO, ZnO, Fe2O3, and preferably CeO2.

[0013] The mass ratio of the metal nitrate to the first carrier molecular sieve is 1-10%, preferably 1-5%, of the metal in the metal nitrate to the mass of the first carrier molecular sieve.

[0014] The second carrier is any one of ceramic granules, ceramic beads, Al2O3 beads, SiO2 beads, activated carbon, sepiolite, and natural zeolite, and preferably ceramic granules.

[0015] The particle size of the second carrier is 1-25 mm, preferably 1-5 mm.

[0016] The application also claims the use of the catalyst prepared by the above preparation method in the treatment of organic wastewater. The prepared shaped catalyst is loaded into a plexiglass organic glass tower reactor, an aqueous solution containing organic matter is added, the mass ratio of the catalyst to the aqueous solution of organic matter is 1:1-1:4, and the catalytic oxidation degradation reaction is carried out by passing ozone from the bottom aeration piece of the tower reactor. The reaction is carried out at normal temperature and pressure for 0.5-2 h.

[0017] In the catalytic ozone oxidation degradation reaction of organic pollutants, after the reaction time reaches the predetermined time, the ozone is first stopped, then the sample is taken through the sampling port in the middle of the tower reactor, the microwave digestion instrument is used for digestion, and the removal amount and removal rate of the solution COD are calculated by titration. Then, the water sample is discharged through the water outlet, and new organic wastewater can be added through the water inlet for the next degradation reaction.

[0018] The catalyst preparation method has the following advantages: the metal oxide can be uniformly dispersed in the first carrier molecular sieve without agglomeration, the molecular sieve loaded with the metal oxide is wrapped outside the second carrier solid particles, the metal oxide can be used to the maximum extent, the overall metal oxide consumption of the catalyst is reduced, the surface hydroxyl group on the molecular sieve also has a certain catalytic activity, which helps to catalyze the generation of hydroxyl radicals with stronger oxidizing property from ozone, and improves the wastewater treatment effect. After the first carrier powder loaded with the metal oxide is wrapped in the second carrier, the silicon sol is sprayed, which can bond the surface powder and enhance the mechanical strength, and the uniform SiO2 layer on the surface improves the hydrophobicity of the molecular sieve and enhances the adsorption of ozone, so that modification treatment is not needed.

[0019] The beneficial effects of the application compared with the prior art are:

[0020] Compared with the prior art, the comprehensive advantages of the present application are that the process for synthesizing the double-carrier catalyst is simple, the raw materials are inexpensive, the catalytic ozone oxidation degradation of organic pollutants in water is good, the treatment effect is good for acid organic pollutants (such as benzoic acid), neutral organic pollutants (such as phenol), and alkaline organic pollutants (such as quinoline), and the COD removal rate reaches more than 90%. The catalyst can be conveniently reused, and the catalyst still has high reactivity after 5 times of reuse. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 X-ray diffraction patterns of CeY with different metal loadings.

[0022] Figure 2 Photos of the catalyst prepared in Example 1.

[0023] Figure 3 Reaction result graph of the catalyst prepared in Example 1 in catalytic ozone oxidation degradation of phenol.

[0024] Figure 4 Reaction result graph of the catalyst prepared in Example 1 in catalytic ozone oxidation degradation of benzoic acid.

[0025] Figure 5 Reaction result graph of the catalyst prepared in Example 1 in catalytic ozone oxidation degradation of quinoline.

[0026] Figure 6 Reaction result graph of the catalyst prepared in Example 2 in catalytic ozone oxidation degradation of phenol. DETAILED DESCRIPTION

[0027] The present application will be described in detail below through specific examples, but the protection scope of the present application is not limited. Unless otherwise specified, the experimental methods used in the present application are conventional methods, and the experimental apparatus, materials, reagents, etc. used can be obtained from commercial channels.

[0028] Example 1

[0029] Preparation method of the double-carrier catalyst of CeY coated ceramsite.

[0030] First, the preparation of NaY loaded with CeO2, take 10g of NaY, mix with Ce(NO3)2 with a metal Ce content of 5% of the mass of NaY, add 150mL of deionized water according to the mass ratio of NaY to deionized water of 1:15, mix and stir, heat at 80℃ and slowly stir to paste, dry at 100℃ for 4h, calcine at 500℃ for 4h, and grind for use.

[0031] The 4mm particle size of ceramsite was washed with water and dried for 2h, 100g of ceramsite was immersed in silica sol for 10min, then taken out and added to a round pot granulator, 5wt.% CeY powder was scattered, and rolling granulation was carried out, and after sieving to remove the powder, 100℃ drying was carried out for 1h, then it was laid flat in a shaking bed and uniformly sprayed with silica sol, and then 100℃ drying was carried out for 1h, and 500℃ calcination was carried out for 4h, and the above operation was repeated once to prepare a shaped catalyst, as shown in Figure 2 The catalyst wrapped twice is shown.

[0032] Example 2

[0033] Preparation method of a double-carrier catalyst of CeY wrapped ceramsite with different particle sizes.

[0034] The difference between this example and Example 1 is that the particle size of the ceramsite selected is 2mm.

[0035] Comparative Example 1

[0036] A CeY catalyst was prepared, phenol solution was used as simulated organic wastewater, and a tank reactor was used to evaluate the catalytic ozone oxidation performance.

[0037] 10g of NaY was mixed with cerium nitrate with a metal Ce content of 1, 3, and 5% of the mass of NaY zeolite, 150mL of deionized water was added according to the mass ratio of zeolite to deionized water of 1:15, and stirred and heated at 80℃ to a paste, dried at 100℃ for 4h, calcined at 500℃ for 4h, and ground to prepare a metal Ce content of 1, 3, and 5wt.% CeY. The X-ray diffraction pattern is shown in Figure 1 As can be seen from the figure, with the increase of the loading amount of metal Ce, the intensity of the characteristic diffraction peaks of the NaY zeolite carrier is lower, but there is no characteristic peak of CeO2, which indicates that Ce is uniformly dispersed on NaY, and the generated CeO2 does not agglomerate.

[0038] In a 500mL batch tank reactor, 200mL of phenol solution with COD=212.50mg / L was added, and 0.10g of the above prepared catalyst was added. Under normal temperature and pressure conditions, ozone was generated by an ozone generator and introduced into the reactor, and magnetic stirring reaction was carried out for 0.5h. After the reaction was completed, the sample was taken, digested by a microwave digestion instrument, and the unreacted potassium dichromate was titrated by ferrous ammonium sulfate, and the residual COD value of the solution was calculated. The reaction results are shown in Table 1.

[0039] Comparative Example 2

[0040] A MgY catalyst was prepared, phenol solution was used as simulated organic wastewater, and a tank reactor was used to evaluate the catalytic ozone oxidation performance.

[0041] The difference between this comparative example and Comparative Example 1 is that the impregnated metal is Mg, and magnesium nitrate is used instead of cerium nitrate in Comparative Example 1. The results of the catalytic reaction of the obtained catalyst are shown in Table 1.

[0042] Comparative Example 3

[0043] MnZSM-5 catalyst was prepared, phenol solution was used as simulated organic wastewater, and a tank reactor was used to evaluate the catalytic ozone oxidation performance thereof.

[0044] 10 g of HZSM-5 was mixed with manganese nitrate in which the content of metal Mn accounted for 1% of the mass of HZSM-5, 150 mL of deionized water was added in an amount of 1:15 of the mass ratio of the molecular sieve to the deionized water, and stirring was performed, heating and slow stirring were performed at 80°C until a paste was formed, drying was performed at 100°C for 4 h, calcination was performed at 500°C for 4 h, and grinding was performed to obtain MnZSM-5 in which the content of metal Mn was 1 wt.%.

[0045] 300 mL of phenol solution with COD = 226.32 mg / L was added to a 500 mL batch tank reactor, and 0.10 g of the above-prepared catalyst was added. Under normal temperature and pressure conditions, ozone was generated by an ozone generator and introduced into the reactor, and magnetic stirring was performed for 0.5 h. After the reaction was completed, sampling was performed, a microwave digestion instrument was used for digestion, and unreacted potassium dichromate was titrated by ferrous ammonium sulfate, and the residual COD value of the solution was calculated. The reaction results are shown in Table 1.

[0046] Comparative Example 4

[0047] MgZSM-5 catalyst was prepared, phenol solution was used as simulated organic wastewater, and a tank reactor was used to evaluate the catalytic ozone oxidation performance thereof.

[0048] The difference between this comparative example and Comparative Example 3 is that the impregnated metal is Mg, and magnesium nitrate is used instead of manganese nitrate in Comparative Example 3. The results of the catalytic reaction of the obtained catalyst are shown in Table 1.

[0049] Comparative Example 5

[0050] After 4 mm particle size of ceramsite was washed with water and dried for 2 h, 100 g of the ceramsite was immersed in silica sol for 10 min, taken out and added to a round pot granulator, NaY powder was scattered and rolled, the powder was removed after sieving, dried at 100°C for 1 h, and then placed in a shaking bed, evenly sprayed with silica sol, and dried at 100°C for 1 h again, and calcined at 500°C for 4 h. The above operation was repeated once to obtain a shaped catalyst.

[0051] Comparative Example 6

[0052] NaY: the mass ratio of ceramsite to NaY is 1:10; 5% of Ce (mass ratio of Ce to NaY) nitrate is added into the silica sol, the ceramsite is immersed in the silica sol for 10 minutes, the NaY powder is wrapped, the silica sol is sprayed, dried at 100°C, and baked at 500°C; the above operation is repeated once.

[0053] Comparative Example 7

[0054] 10g of NaY is mixed with 5% of Ce (mass ratio of Ce to NaY) nitrate; the mass ratio of NaY to H2O is 1:15

[0055] , mixed and stirred at 80°C, evaporated and dried at 100°C, and baked at 500°C; the mass ratio of CeY to ceramsite is 1:10, the ceramsite is immersed in the silica sol for 10 minutes, the CeY powder is wrapped, dried at 100°C, and baked at 500°C; the above operation is repeated once.

[0056] Application Example 1

[0057] The catalytic ozonation performance of the catalyst obtained in Example 1 is evaluated by using a phenol solution as simulated organic wastewater.

[0058] 100g of the CeY-wrapped ceramsite catalyst prepared in Example 1 is loaded into an acrylic organic glass tower reactor, 400mL of a phenol solution with COD=1034.54mg / L is added, ozone is introduced from the bottom of the tower reactor through an aeration piece, and a catalytic ozonation degradation reaction is carried out at normal temperature and pressure for 1h. After the reaction, the water sample is discharged through the water outlet, and the same newly prepared phenol solution is added again for two times of repeated use of the catalyst. The sample is digested by a microwave digestion instrument, and the unreacted potassium dichromate is titrated by ferrous ammonium sulfate, and the residual COD value of the solution is calculated. The reaction results are shown in Table 1, Figure 3 . It can be seen from Figure 3 that the catalytic activity does not decrease obviously in the repeated use of the catalyst, and the removal rate of phenol COD is more than 90%.

[0059] Application Example 2

[0060] The catalytic ozonation performance of the catalyst obtained in Example 1 is evaluated by using a benzoic acid solution as simulated organic wastewater.

[0061] The difference between this application example and Application Example 1 is that the solution of a certain concentration of organic matter is selected as a benzoic acid solution with pH=5 and COD=963.67mg / L, and the reaction results are shown in Table 1, Figure 4 . It can be seen from Figure 4 that the catalytic activity does not decrease obviously in the repeated use of the catalyst, and the removal rate of benzoic acid COD is more than 90%.

[0062] Application Example 3

[0063] The catalytic ozonation performance of the catalyst obtained in Example 1 was evaluated by using quinoline solution as simulated organic wastewater.

[0064] The difference between the present application example and Application Example 1 is that the solution of organic matter with a certain concentration is quinoline solution with COD = 944.39 mg / L, and the reaction time is 2 h. The reaction results are shown in Table 1, Figure 5 It can be seen from Figure 5 that the catalytic activity of the catalyst does not decrease obviously in repeated use, and the removal rate of quinoline COD is more than 90%.

[0065] Application Example 4

[0066] The catalytic ozonation performance of the catalyst obtained in Example 2 was evaluated by using phenol solution as simulated organic wastewater.

[0067] 100 g of the CeY-coated ceramic catalyst prepared in Example 2 was loaded into an acrylic organic glass tower reactor, 400 mL of phenol solution with COD = 1034.54 mg / L was added, ozone was introduced from the bottom of the tower reactor through an aeration piece, and a catalytic ozonation degradation reaction was carried out at normal temperature and pressure for 1 h. After the reaction, the water sample was discharged through the water outlet, and the same freshly prepared phenol solution was added again for two times of catalyst reuse experiments. The sample was digested by a microwave digestion instrument, and the unreacted potassium dichromate was titrated by ferrous ammonium sulfate, and the residual COD value of the solution was calculated. The reaction results are shown in Table 1, Figure 6 It can be seen from Figure 6 that the catalytic activity of the catalyst does not decrease obviously in repeated use, and the removal rate of quinoline COD is more than 90%.

[0068] Application Comparative Example 1

[0069] The catalytic ozonation performance of the catalyst obtained in Example 2 was evaluated by using phenol solution as simulated organic wastewater.

[0070] The difference between the present application example and Application Example 1 is that the solution of organic matter with a certain concentration is quinoline solution with COD = 944.39 mg / L, and the reaction time is 2 h. The reaction results are shown in Table 1,

[0071] Application Comparative Example 2

[0072] The catalytic ozonation performance of the catalyst obtained in Example 2 was evaluated by using phenol solution as simulated organic wastewater.

[0073] The difference between the present application example and Application Example 1 is that the solution of organic matter with a certain concentration is quinoline solution with COD = 944.39 mg / L, and the reaction time is 2 h. The reaction results are shown in Table 1,

[0074] Table 1: Results of ozone catalytic oxidation reaction of each example and comparative example

[0075]

[0076]

[0077] Note: a the second use of the catalyst; b the third use of the catalyst; c the fourth use of the catalyst; d the fifth use of the catalyst.

[0078] The present application is directed to the preparation method and effect list of the technical solutions of the comparative example and the present application as shown below:

[0079]

[0080]

[0081] The above-described embodiments are merely preferred embodiments of the present application and are not all the embodiments that can be implemented by the present application. Any obvious modifications made by those skilled in the art without departing from the principles and spirit of the present application should be considered to be included in the scope of protection of the claims of the present application.

Claims

1. A process for the preparation of a dual-support metal oxide catalyst, characterized in that, First, the metal oxide is loaded on the first carrier, the metal oxide is uniformly dispersed on the first carrier by the method of constant temperature immersion and evaporation drying at 80 DEG C, and the powder is obtained after drying at 100 DEG C, calcining at 500 DEG C and grinding, then the powder is wrapped on the second carrier to prepare a double carrier catalyst; The specific steps are as follows: S1. Preparation of molecular sieve loaded metal oxide, take a certain mass ratio of metal nitrate and first carrier molecular sieve, add deionized water according to the mass ratio of first carrier molecular sieve to deionized water 1:15, mix and stir, heat at 80 DEG C and slowly stir to paste, dry at 100 DEG C for 4 h, calcine at 500 DEG C for 4 h, and grind for standby; The powder of molecular sieve loaded metal oxide is obtained; S2. The powder prepared in S1 is wrapped on the second carrier, the second carrier with different particle size specifications is washed with water and dried for 2 h, the second carrier with 10 times the mass of the powder prepared in S1 is taken, silicon sol is added to immerse for 10 min, then poured into a round pot granulator, the powder of molecular sieve loaded metal oxide prepared in step S1 is scattered, and the granulation is carried out by rolling, then the powder is removed by sieving, dried at 100 DEG C for 1 h, then placed in a shaking bed and laid flat, evenly sprayed with silicon sol, then dried at 100 DEG C for 1 h, calcined at 500 DEG C for 4 h, and the above operation is repeated 1-4 times to obtain the catalyst; The particle size of the second carrier is 1-5 mm; The first carrier molecular sieve is any one of Y, ZSM-5, beta, MOR; The second carrier is any one of ceramic granules, ceramic pellets, Al2O3 pellets, SiO2 pellets, activated carbon, sepiolite, natural zeolite.

2. The method of making a dual-support supported metal oxide catalyst of claim 1, wherein, The metal oxide in the loaded metal oxide is any one or more than two of MnO2, CeO2, MgO, NiO, Co3O4, CuO, ZnO, Fe2O3.

3. The method for preparing a dual-supported metal oxide catalyst as described in claim 2, characterized in that, The mass ratio of metal nitrate to first carrier molecular sieve is that the metal in the metal nitrate is 1-10% of the mass of the first carrier molecular sieve.

4. Use of a catalyst prepared according to the process of any one of claims 1 to 3 for the treatment of organic waste water, characterized in that, The prepared shaped catalyst is loaded into an acrylic organic glass tower reactor, an aqueous solution containing organic matter is added, the mass ratio of catalyst to aqueous solution of organic matter is 1:1-1:4, the catalytic oxidation degradation reaction is carried out by passing ozone from the bottom of the tower reactor through the aeration piece, and the reaction is carried out at normal temperature and pressure for 0.5-2 h.

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