Co3O4@alpha-MnO2 material, and preparation method and application thereof

Abstract

The application discloses a Co3O4@alpha-MnO2 material and a preparation method and application thereof, and belongs to the technical field of catalyst preparation and atmospheric pollution control. 4+ The Co3O4@alpha-MnO2 material prepared by the application has higher surface Mn 4+ concentration, stronger reduction capacity, and higher surface active oxygen species content and migration rate. In the removal of p-chlorobenzene, the Co3O4@alpha-MnO2 material exhibits higher catalytic activity and CO2 yield in the high-temperature section, and exhibits higher tolerance to actual industrial flue gas components such as SO2, NO and toluene.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of catalyst preparation and air pollution control, and particularly relates to a Co3O4@alpha-MnO2 material, a preparation method and application thereof. BACKGROUND

[0002] Most VOCs have high photochemical reactivity and are easy to react with NO x to form ozone or adhere to fine particulate matter PM 2.5 . Chlorine-containing volatile organic compounds (CVOCs) are important precursors of PM 2.5 and O3 formation, and become the focus of attention in the field of VOCs treatment due to their high toxicity, high stability, and difficult degradation.

[0003] Among the many treatment technologies for CVOCs, catalytic oxidation technology is considered a promising end-of-pipe technology and is very suitable for industrial applications. The core of catalytic oxidation technology lies in the selection of catalysts. Although the catalytic activity of transition metals is inferior to that of noble metals, the low cost, high resistance to chlorine poisoning, and good high-temperature thermal stability of transition metals make them widely used in the field of catalysis. Manganese is favored by researchers due to its special Mn 2+ / Mn 3+ / Mn 4+ redox cycle, high reserves on earth, low cost, and non-toxicity, and is widely used in the catalytic oxidation of CVOCs. It has been reported that the redox cycle between the multiple valence states of manganese produces oxygen defects, thereby promoting the adsorption and activation of oxygen and generating abundant oxygen species for the oxidation of CVOCs.

[0004] Manganese elements with multiple valence states can exhibit multiple crystal structures (such as MnO2, Mn2O3, Mn3O4, etc.), and these different crystal structures have different catalytic oxidation performances for CVOCs. It is worth noting that MnO2 calcined at medium-high temperatures is outstanding among various MnO x catalysts due to its excellent oxygen species mobility. However, MnO2 has poor catalytic activity for chlorobenzene and low CO2 yield, especially poor catalytic activity and CO2 yield at high temperatures, and poor practical industrial application ability. SUMMARY

[0005] In view of the above shortcomings of the prior art, the application provides a Co3O4@alpha-MnO2 material, a preparation method and application thereof.

[0006] To achieve the above-mentioned purposes, the technical solutions adopted by the application are as follows:

[0007] A preparation method of a Co3O4@alpha-MnO2 material, comprising the following steps:

[0008] (1) adding KMnO4 and (NH4)2C2O4.H2O into water, ultrasonic dispersion, then hydrothermal reaction, finally filtering, washing, drying, and calcining to obtain a rod-like alpha-MnO2 material;

[0009] (2) placing the rod-like alpha-MnO2 material, Co(NO3)2.6H2O, and urea into water, then hydrothermal reaction, finally filtering, washing, drying, and calcining to obtain the Co3O4@alpha-MnO2 material.

[0010] The present application adopts urea, which not only uniformly disperses Co elements on the surface of the rod-like alpha-MnO2 material, but also can improve the catalytic activity and CO2 yield of the material in the process of catalytic oxidation of chlorobenzene.

[0011] As a preferred embodiment of the present application, the mass ratio or molar ratio of the KMnO4 and (NH4)2C2O4.H2O is 2:1.

[0012] As a preferred embodiment of the present application, in the step (1), the temperature of the hydrothermal reaction is 180℃, and the time is 24h.

[0013] As a preferred embodiment of the present application, in the step (1), the atmosphere condition of the calcining is air atmosphere, the temperature of the calcining is 400℃, and the time is 4h.

[0014] The present application adopts the above hydrothermal temperature, time, and calcining temperature and time to obtain the rod-like alpha-MnO2 material. If the parameters of the hydrothermal and calcining are not within the range defined by the present application, the rod-like alpha-MnO2 material cannot be generated, and the improvement of the chlorobenzene conversion rate and CO2 yield of the composite material at 350℃ is not obvious.

[0015] As a preferred embodiment of the present application, the mass ratio of the rod-like alpha-MnO2 material and Co(NO3)2.6H2O is 1:0.025-0.5; and the molar ratio of the Co(NO3)2.6H2O and urea is 1:10.

[0016] As a preferred embodiment of the present application, in the step (2), the temperature of the hydrothermal reaction is 120℃, and the time is 12h.

[0017] As a preferred embodiment of the present application, in the step (2), the atmosphere condition of the calcining is air atmosphere, the heating rate is 2℃ / min, the temperature of the calcining is 400℃, and the time of the calcining is 4h.

[0018] The Co3O4@alpha-MnO2 material prepared by the preparation method of the Co3O4@alpha-MnO2 material of the present application.

[0019] As a preferred embodiment of the present application, the Co3O4@alpha-MnO2 material is Co3O4 loaded on the surface of rod-shaped alpha-MnO2 material.

[0020] As a preferred embodiment of the present application, the Co3O4@alpha-MnO2 material is applied in catalytic oxidation of chlorobenzene.

[0021] Compared with the prior art, the present application has the following beneficial effects: the present application modifies the surface of rod-shaped alpha-MnO2 material with Co3O4, which improves the catalytic activity and CO2 yield of the material in the process of catalytic oxidation of chlorobenzene at high temperature (compared with the original alpha-MnO2, the catalytic activity and CO2 yield are improved by 34%), greatly reduces the degree of deactivation in the continuous experiment, and shows higher resistance and anti-interference to SO2, NO and toluene and other actual industrial flue gas components, thereby improving the potential of actual industrial application. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 Figure 1 is a scanning electron microscope (SEM) image of alpha-MnO2 and 1Co@alpha-MnO2 samples of the present application; (a) is the alpha-MnO2 material prepared in Comparative Example 1; (b) is the 1Co@alpha-MnO2 sample prepared in Example 3.

[0023] Figure 2 Figure 2 is a graph of catalytic activity and CO2 yield of chlorobenzene of the samples prepared in Examples 1-4 and Comparative Example 1 of the present application; (a) is a graph of catalytic activity of chlorobenzene; (b) is a graph of CO2 yield.

[0024] Figure 3 Figure 3 is a durability test graph of the samples prepared in Comparative Example 1 and Example 3 of the present application.

[0025] Figure 4 Figure 4 is a durability test graph of the samples prepared in Comparative Example 1 and Example 3 of the present application after introduction of coexisting components; (a) is a durability test graph after introduction of SO2; (b) is a durability test graph after introduction of NO; (c) is a durability test graph after introduction of toluene.

[0026] Figure 5 Figure 5 is a graph of catalytic activity of chlorobenzene oxidation of the samples prepared in Comparative Examples 2-4 of the present application. DETAILED DESCRIPTION

[0027] In order to better illustrate the purpose, technical scheme and advantages of the present application, the present application will be further described below in combination with specific examples.

[0028] Example 1

[0029] A method for preparing a Co3O4@α-MnO2 material, comprising the following steps:

[0030] (1) Take 3.16 g of KMnO4 and 1.42 g of (NH4)2C2O4·H2O and add them to 70 mL of deionized water, ultrasonic dispersion for 20 min, fully dissolve and mix, to obtain a purple mixed solution.

[0031] (2) Transfer the purple solution to a high-pressure reaction kettle, and perform hydrothermal reaction at 180℃ for 24 h.

[0032] (3) After cooling, filter the precipitate, wash it with deionized water for 3-5 times, and place it in a 80℃ oven for drying for 12-14 h.

[0033] (4) Grind the dried sample, and place it in a tube furnace under air atmosphere, heat it to 400℃ at a heating rate of 2℃ / min and keep it for 4 h for calcination, to obtain a rod-shaped α-MnO2 carrier.

[0034] (5) Take 1 g of the α-MnO2 carrier, 0.05 g of Co(NO3)2·6H2O and 0.1 g of urea (molar ratio of Co(NO3)2·6H2O to urea is 1:10), dissolve them in 70 mL of deionized water, ultrasonic dispersion for 20-30 min to obtain a mixed solution.

[0035] (6) Transfer the mixed solution to a high-pressure reaction kettle, and perform hydrothermal reaction at 120℃ for 12 h, after cooling to room temperature, filter and wash the obtained precipitate with deionized water for 3-5 times, then place it in a 80℃ oven for drying for 12-14 h, and then heat it to 400℃ at a heating rate of 2℃ / min and calcine it under air atmosphere for 4 h, to obtain a Co3O4 surface-modified rod-shaped α-MnO2 material, marked as 0.5Co@α-MnO2.

[0036] Example 2

[0037] A method for preparing a Co3O4@α-MnO2 material, and the only difference from Example 1 is that in step (5), the mass of Co(NO3)2·6H2O is 0.1 g, and the mass of urea is 0.2 g. The finally obtained Co3O4@α-MnO2 material is marked as 1Co@α-MnO2.

[0038] As shown in FIG. b, the synthesized 1Co@α-MnO2 sample still presents a good rod-like morphology, indicating that the loading of Co3O4 does not change the morphology of the original α-MnO2. Figure 1

[0039] Example 3​

[0040] The only difference between the preparation method of the Co3O4@ a-MnO2 material and Example 1 is that in the step (5), the mass of Co(NO3)2·6H2O is 0.5 g and the mass of urea is 1.0 g. The finally obtained Co3O4@ a-MnO2 material is marked as 5Co@ a-MnO2.

[0041] The synthesized 5Co@ a-MnO2 sample still presents a good rod-like morphology, which indicates that the loading of Co3O4 does not change the morphology of the original a-MnO2.

[0042] Example 4

[0043] The only difference between the preparation method of the Co3O4@ a-MnO2 material and Example 1 is that in the step (5), the mass of Co(NO3)2·6H2O is 1.0 g and the mass of urea is 2.0 g. The finally obtained Co3O4@ a-MnO2 material is marked as 10Co@ a-MnO2.

[0044] The synthesized 10Co@ a-MnO2 sample still presents a good rod-like morphology, which indicates that the loading of Co3O4 does not change the morphology of the original a-MnO2.

[0045] Comparative Example 1

[0046] A preparation method of an a-MnO2 material, comprising the following steps:

[0047] (1) 3.16 g of KMnO4 and 1.42 g of (NH4)2C2O4·H2O are weighed and added to 70 mL of deionized water, and the solution is ultrasonically dispersed for 20-30 min to fully mix and obtain a purple mixed solution.

[0048] (2) The purple solution is transferred to a high-pressure reaction kettle, and a hydrothermal reaction is carried out at 180℃ for 24 h.

[0049] (3) After cooling, the precipitate is filtered, washed with deionized water for 3-5 times, and placed in a 80℃ oven for drying for 12-14 h.

[0050] (4) The dried sample is ground and placed in a tube furnace under air atmosphere, and heated to 400℃ at a heating rate of 2℃ / min and kept for 4 h for calcination to obtain rod-like a-MnO2. The scanning electron microscope image thereof is shown in FIG. a, and the synthesized rod-like a-MnO2 sample presents a good rod-like morphology. Figure 1

[0051] Comparative Example 2

[0052] ​A preparation method of a Co3O4 / α-MnO2 material, comprising the following steps:

[0053] (1) 3.16 g of KMnO4 and 1.42 g of (NH4)2C2O4·H2O are weighed and added to 70 mL of deionized water, and the solution is ultrasonically dispersed for 20 min, fully mixed, and a purple mixed solution is obtained.

[0054] (2) The purple solution is transferred to a high-pressure reaction kettle, and a hydrothermal reaction is carried out at 180°C for 24 h.

[0055] (3) After cooling, the precipitate is filtered, washed with deionized water for 3-5 times, and placed in a 80°C oven for drying for 12-14 h.

[0056] (4) The dried sample is ground, and is placed in a tube furnace under an air atmosphere, heated to 400°C at a heating rate of 2°C / min, and calcined for 4 h to obtain a rod-shaped α-MnO2 carrier.

[0057] (5) 0.1 g of Co(NO3)2·6H2O is weighed and dissolved in 9.5 mL of deionized water, and the solution is ultrasonically dispersed for 20-30 min, fully mixed, and a light red solution is obtained.

[0058] (6) 1 g of the α-MnO2 carrier is weighed in a beaker, and the light red solution is uniformly dropped and ultrasonically dispersed for 20-30 min, and after standing overnight, it is placed in a 80°C oven for drying for 12-14 h.

[0059] (7) The dried sample is ground, and is placed in a tube furnace under an air atmosphere, heated to 400°C at a heating rate of 2°C / min, and calcined for 4 h to obtain a Co3O4 surface modified α-MnO2 prepared by an equal volume impregnation method, which is marked as 1Co / α-MnO2, indicating that the mass fraction of Co3O4 on the Co3O4 surface modified α-MnO2 catalyst prepared in this comparative example is 1%.

[0060] Comparative Example 3

[0061] The preparation method of the Co3O4 / α-MnO2 material in the comparative example is only different from that in Comparative Example 2 in that in step (5), the mass of Co(NO3)2·6H2O is 0.5 g. The finally obtained Co3O4 / α-MnO2 material is marked as 5Co / α-MnO2, indicating that the mass fraction of Co3O4 on the Co3O4 surface modified α-MnO2 catalyst prepared in this comparative example is 5%.

[0062] Comparative Example 4

[0063] The preparation method of the Co3O4 / α-MnO2 material in the present comparative example is only different from that in Comparative Example 2 in that in the step (5), the mass of Co(NO3)2·6H2O is 1.0 g. The finally obtained Co3O4 / α-MnO2 material is marked as 10Co / α-MnO2, indicating that the mass fraction of Co3O4 on the Co3O4 surface modified α-MnO2 catalyst prepared in the present comparative example is 10%.

[0064] Comparative Example 5

[0065] A preparation method of a Co3O4@α-MnO2 material, comprising the following steps:

[0066] (1) 6.99 g of MnSO4·H2O and 4.36 g of KMnO4 were weighed and dissolved in 50 mL of deionized water, respectively.

[0067] (2) The above two solutions were uniformly added to 50 mL of deionized water, and stirred at 60°C water bath for 2 h.

[0068] (3) The above solution was filtered and washed to neutral to obtain a precipitate, and the precipitate was dried at 80°C for 12 h.

[0069] (4) The dried sample was ground and placed in a tube furnace under air atmosphere, and heated to 400°C at a heating rate of 2°C / min and kept for 12 h for calcination to obtain spherical α-MnO2.

[0070] (5) 1 g of spherical α-MnO2 carrier, 0.05 g of Co(NO3)2·6H2O and 0.1 g of urea (molar ratio of Co(NO3)2·6H2O to urea is 1:10) were weighed and dissolved in 70 mL of deionized water, and a mixed solution was prepared after ultrasonic dispersion for 20-30 min.

[0071] (6) The mixed solution was transferred to a high-pressure reaction kettle and subjected to hydrothermal reaction at 120°C for 12 h, and after cooling to room temperature, the obtained precipitate was filtered and washed with deionized water for 3-5 times and then dried in an oven at 80°C for 12-14 h, and then heated to 400°C at a heating rate of 2°C / min and calcined for 4 h under air atmosphere to obtain a Co3O4 surface modified rod-like α-MnO2 material.

[0072] Comparative Example 6

[0073] A preparation method of a Co3O4@α-MnO2 material, comprising the following steps:

[0074] (1) 1.69 g of MnSO4·H2O and 3.95 g of KMnO4 were weighed and dissolved in 80 mL of deionized water.

[0075] (2) The above solution was transferred to a high-pressure reactor and hydrothermally reacted at 100°C for 12 h.

[0076] (3) After cooling to room temperature, the obtained precipitate was filtered, washed 3-5 times with deionized water, and then dried in an oven at 100°C for 12 h.

[0077] (4) The temperature was increased to 500°C at a rate of 2°C / min under an air atmosphere and calcined for 6 h to obtain flower-like a-MnO2.

[0078] (5) 1 g of the flower-like a-MnO2 support, 0.05 g of Co(NO3)2·6H2O, and 0.1 g of urea (molar ratio of Co(NO3)2·6H2O to urea was 1:10) were weighed out, dissolved in 70 mL of deionized water, and ultrasonically dispersed for 20-30 min until uniform to prepare a mixed solution.

[0079] (6) The mixed solution was transferred to a high-pressure reactor and hydrothermally reacted at 120°C for 12 h. After cooling to room temperature, the obtained precipitate was filtered, washed 3-5 times with deionized water, and then dried in an oven at 80°C for 12-14 h. Then the temperature was increased to 400°C at a rate of 2°C / min under an air atmosphere and calcined for 4 h to obtain a Co3O4 surface-modified rod-like a-MnO2 material.

[0080] Comparative Example 7

[0081] A method for preparing a Co3O4@δ-MnO2 material, comprising the following steps:

[0082] (1) 1.35 g of KMnO4 and 1.0 mL of HCl (37 wt%) were weighed out and dissolved in 120 mL of deionized water.

[0083] (2) The above solution was transferred to a high-pressure reactor and hydrothermally reacted at 120°C for 12 h.

[0084] (3) After cooling to room temperature, the obtained precipitate was filtered, washed 3-5 times with deionized water, and then dried in an oven at 120°C for 12 h.

[0085] (4) The temperature was increased to 80°C at a rate of 2°C / min under an air atmosphere and calcined for 12 h to obtain δ-MnO2.

[0086] (5) 1 g of the δ-MnO2 support, 0.05 g of Co(NO3)2·6H2O, and 0.1 g of urea (molar ratio of Co(NO3)2·6H2O to urea was 1:10) were weighed out, dissolved in 70 mL of deionized water, and ultrasonically dispersed for 20-30 min until uniform to prepare a mixed solution.

[0087] (6) The mixed solution is transferred to a high-pressure reactor for hydrothermal reaction at 120°C for 12h. After cooling to room temperature, the obtained precipitate is filtered and washed with deionized water for 3-5 times, and then dried in an oven at 80°C for 12-14h. Then, the temperature is increased to 400°C at a rate of 2°C / min under air atmosphere and calcined for 4h to obtain a Co3O4 surface-modified δ-MnO2 material.

[0088] Comparative Example 8

[0089] A preparation method of a Co3O4@δ-MnO2 material, comprising the following steps:

[0090] (1) 6.32g of MnSO4 and 8.56g of (NH4)2S2O8 are weighed and dissolved in 150mL of deionized water.

[0091] (2) The above solution is transferred to a high-pressure reactor for hydrothermal reaction at 90°C for 24h.

[0092] (3) After cooling to room temperature, the obtained precipitate is filtered and washed with deionized water and ethanol for 3-5 times, and then dried in an oven at 120°C for 12h.

[0093] (4) The temperature is increased to 80°C at a rate of 2°C / min under air atmosphere and calcined for 12h to obtain γ-MnO2.

[0094] (5) 1g of the γ-MnO2 carrier, 0.05g of Co(NO3)2·6H2O and 0.1g of urea (molar ratio of Co(NO3)2·6H2O to urea is 1:10) are weighed and dissolved in 70mL of deionized water, and the mixed solution is uniformly dispersed by ultrasonic for 20-30min.

[0095] (6) The mixed solution is transferred to a high-pressure reactor for hydrothermal reaction at 120°C for 12h. After cooling to room temperature, the obtained precipitate is filtered and washed with deionized water for 3-5 times, and then dried in an oven at 80°C for 12-14h. Then, the temperature is increased to 400°C at a rate of 2°C / min under air atmosphere and calcined for 4h to obtain a Co3O4 surface-modified γ-MnO2 material.

[0096] Effect Example

[0097] (1) A certain amount of catalyst is subjected to chlorobenzene catalytic oxidation activity evaluation on a fixed bed reactor, and the catalyst evaluation conditions are as follows:

[0098] The atmosphere conditions for simulating catalytic oxidation of chlorobenzene were: 600 ppm chlorobenzene, 10% O2, N2 balance gas, gas flow rate = 100 mL / min, corresponding reaction space velocity WHSV = 30000 mL / (g h), temperature was 100-450, chlorobenzene concentration and CO2 concentration were tested every 50°C. The chlorobenzene conversion rate and CO2 yield were calculated by using the measured chlorobenzene concentration and CO2 concentration before and after the reaction, and the results are shown in Table 1 and Figure 2 .

[0099] (2) A certain mass of catalyst was subjected to continuous chlorobenzene catalytic oxidation activity evaluation on a fixed bed reactor, and the catalyst evaluation conditions were as follows:

[0100] The atmosphere conditions for simulating catalytic oxidation of chlorobenzene were: 600 ppm chlorobenzene, 10% O2, N2 balance gas, gas flow rate = 100 mL / min, corresponding reaction space velocity WHSV = 30000 mL / (g h), temperature was 350°C, time was 18h. The difference between the chlorobenzene conversion rate at the beginning of the reaction and after 18h was the 18h chlorobenzene degradation rate, and the results are shown in Figure 3 .

[0101] Table 1

[0102]

[0103] According to Figure 2 , the α-MnO2 prepared in Comparative Example 1 has higher activity at a low temperature of about 250°C, but is easily deactivated, and the CO2 yield is also relatively low. The samples prepared in Examples 1-4 have improved high-temperature catalytic activity for chlorobenzene, and the CO2 yield is also greatly improved, and 1Co@α-MnO2 exhibits the best catalytic activity at high temperatures, with a 34% increase in CO2 yield compared to the α-MnO2 prepared in Comparative Example 1. According to Figure 5 and Table 1, the catalytic activity of the materials prepared in Comparative Examples 2-4 for chlorobenzene does not significantly improve compared to the α-MnO2 prepared in Comparative Example 1, and even decreases, but the CO2 yield improves. According to Figure 3 , the activity of the α-MnO2 sample prepared in Comparative Example 1 decreases continuously in the durability test (decreases by 14% in the 18h test), and has poor durability. And according to Table 1 and Figure 3 , the chlorobenzene conversion rate of the samples prepared in Examples 1-4 is basically unchanged in the 18h test.

[0104] In Comparative Examples 2-4, the samples obtained by equal-volume impregnation loading have uneven Co dispersion, which occupies the active sites on the surface of α-MnO2, and the performance decreases, the catalytic effect cannot be improved, and instead decreases, so the chlorobenzene degradation rate in the durability test will decrease more than α-MnO2.

[0105] The conversion rate and CO2 yield of the comparative examples 5-8 are significantly lower than the sample with rod-like α-MnO2 as the carrier, because the conversion rate of chlorobenzene is below 90% at 350°C and the chlorobenzene degradation rate decreases significantly in 18h for the composite material with spherical, flower-like or δ-MnO2 or γ-MnO2 as the carrier, and the catalytic effect is not durable.

[0106] (3) The anti-interference evaluation of the chlorobenzene catalytic oxidation activity of a certain amount of catalyst on a fixed bed reactor is carried out, and the anti-interference evaluation conditions are as follows:

[0107] The simulated catalytic oxidation atmosphere of chlorobenzene is as follows: 600ppm chlorobenzene, interference gas (100ppm SO2 or 100ppm NO or 500ppm toluene), 10% O2, N2 balance gas, gas flow rate = 100mL / min, corresponding reaction space velocity WHSV = 30000mL / (g·h), temperature is 350°C, and time is 18h. The difference between the chlorobenzene conversion rate at the beginning of the reaction and after 18h is used, and the results are shown in Figure 4 .

[0108] According to Figure 4 , it can be known that the SO2, NO and toluene in the actual industrial flue gas composition have a relatively significant influence on the catalytic oxidation activity of chlorobenzene of the α-MnO2 sample prepared in the comparative example 1, and the anti-interference ability is weak. However, the influence of SO2, NO and toluene in the actual industrial flue gas composition on the catalytic oxidation activity of chlorobenzene of the material prepared in the example 1 is relatively small, which indicates that the anti-interference ability of the Co3O4@α-MnO2 material is improved.

[0109] And after the material performance analysis test, it is found that the sample prepared in the example 2 after loading Co3O4 has the highest surface Mn 4+ concentration, stronger reduction capacity and higher content and migration rate of surface active oxygen species, so the redox capacity is the strongest, and the anti-interference performance is the best. The anti-interference ability of SO2, NO and toluene of the examples 1, 3-4 is enhanced due to the loading of rod-like α-MnO2. However, for the comparative examples 2-8, the anti-interference ability of SO2, NO and toluene is worse than that of the original α-MnO2 due to the poor dispersity of the sample Co3O4 or due to the change of the morphology or material structure.

[0110] Finally, it should be noted that the above examples are only used to illustrate the technical solutions of the present application, but not to limit the protection scope of the present application. Although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or replaced equivalently without departing from the essence and scope of the technical solutions of the present application.

Claims

1. Use of a Co304@ a-Mn02 material in catalytic oxidation of chlorobenzene, characterized in that, The preparation method of the Co3O4@α-MnO2 material comprises the following steps: (1) adding KMnO4 and (NH4)2C2O4·H2O according to a molar ratio of 2:1 into water for ultrasonic dispersion, then carrying out hydrothermal reaction at 180 ℃ for 24 h, and finally filtering, washing, drying, and calcining at 400 ℃ in air for 4 h to obtain a rod-like α-MnO2 material; (2) placing the rod-like α-MnO2 material, Co(NO3)2·6H2O, and urea in water, then carrying out hydrothermal reaction, and finally filtering, washing, drying, and calcining to obtain the Co3O4@α-MnO2 material.

2. The use according to claim 1, characterized in that, The mass ratio of the rod-like α-MnO2 material and Co(NO3)2·6H2O is 1:0.025-0.5, and the molar ratio of Co(NO3)2·6H2O and urea is 1:

10.

3. The use according to claim 1, characterized in that, In the step (2), the temperature of the hydrothermal reaction is 120 ℃, and the time is 12 h.

4. The use according to claim 1, characterized in that, In the step (2), the atmosphere condition of the calcination is air atmosphere, the heating rate is 2 ℃ / min, the calcination temperature is 400 ℃, and the calcination time is 4 h.

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