Chlorine-doped manganese oxide, preparation method and application thereof, and method for decomposing ozone

Abstract

The present application relates to the field of catalytic decomposition of ozone technology, and specifically provides a chlorine-doped manganese oxide and its preparation method and application and ozone decomposition method. The preparation method of the chlorine-doped manganese oxide comprises: subjecting permanganate and chloride to a hydrothermal synthesis reaction, the reaction temperature is 100°C-200°C, and the reaction time is 10h-40h. The preparation method of the chlorine-doped manganese oxide provided in the present application can effectively improve the oxygen vacancy moisture resistance of manganese dioxide, and the method has the characteristics of simple process and low cost.

Description

Technical Field

[0001] The present application relates to the technical field of catalytic decomposition of ozone, and in particular, to a method for preparing a doped manganese oxide, a doped manganese oxide prepared by the preparation method, and applications of the doped manganese oxide and a method for decomposing ozone. Background Art

[0002] Nitrogen oxides and volatile organic compounds undergo photochemical reactions under sunlight, leading to global near-ground ozone pollution. In daily life, some household appliances, such as air purifiers, printers, televisions, and electronic sterilizers that use plasma or static electricity as a removal method, have become common sources of ozone. Ozone generated indoors has already had an impact on human health, and long-term exposure to even low concentrations of ozone can cause respiratory and cardiovascular-related diseases. In addition, indoor ozone also reacts with other substances to form secondary pollutants, which may also cause varying degrees of harm to health. Therefore, it is very necessary to develop an efficient and environmentally friendly method to remove ozone pollutants.

[0003] Catalytic removal of ozone is a safe, economical and efficient method. Supported precious metal catalysts have high performance in catalyzing ozone decomposition, but the high price and scarce resources of precious metals limit the large-scale application of precious metal catalysts. Metal oxides have also been developed as catalysts for ozone removal, but metal oxide catalysts are more sensitive to moisture, and the catalyst activity decreases or even gradually deactivates. In actual application scenarios, there will always be varying degrees of humidity in the air, so the development of catalysts that can stably catalyze ozone decomposition in the presence of water vapor, especially under high humidity, has great application prospects. It is of great significance to protect people from ozone pollution in daily production and life and to ensure people's health. Summary of the invention

[0004] The purpose of the present application is to provide a chlorine-doped manganese oxide and its preparation method and application and a method for decomposing ozone. The preparation method of the present application can effectively improve the oxygen vacancy moisture resistance of manganese dioxide, and has the characteristics of simple process and low cost.

[0005] In a first aspect, the present application provides a method for preparing chlorine-doped manganese oxide, comprising: subjecting permanganate and chloride to a hydrothermal synthesis reaction, wherein the temperature of the hydrothermal synthesis reaction is 100° C.-200° C., and the reaction time is 10 h-40 h.

[0006] In some embodiments, the permanganate includes one or more of potassium permanganate, sodium permanganate, and ammonium permanganate.

[0007] In some embodiments, the chloride comprises ammonium chloride.

[0008] In some embodiments, the molar ratio of the permanganate to the chloride is 1:(0.5-1.5).

[0009] Furthermore, the molar ratio of the permanganate to the chloride is 1:(0.9-1.2).

[0010] In some embodiments, the preparation method comprises the following steps:

[0011] dissolving the permanganate and the chloride in water to obtain a reaction solution;

[0012] subjecting the reaction solution to the hydrothermal synthesis reaction;

[0013] In the reaction solution, the total concentration of the permanganate and the chloride is 0.1 mol / L-10 mol / L.

[0014] In some embodiments, the preparation method further comprises: after the hydrothermal synthesis reaction, performing solid-liquid separation, washing and drying on the obtained reaction product.

[0015] Furthermore, the drying temperature is 60°C-200°C, and the drying time is 6h-24h.

[0016] In a second aspect, the present application provides chlorine-doped manganese oxide prepared by the preparation method described in the first aspect of the present application.

[0017] In some embodiments, the mass fraction of chlorine in the chlorine-doped manganese oxide is 0.06%-2.20%.

[0018] In some embodiments, the chlorine-doped manganese oxide has an average pore size of 4.8 nm to 7.2 nm and a specific surface area of ​​270 m 2 / g-350m 2 / g.

[0019] In a third aspect, the present application provides the use of the chlorine-doped manganese oxide as an ozone decomposition catalyst.

[0020] In a fourth aspect, the present application provides a method for decomposing ozone, the method comprising: subjecting an ozone-containing gas to a decomposition reaction in the presence of the chlorine-doped manganese oxide.

[0021] The preparation method of the present application can effectively improve the oxygen vacancy moisture resistance of manganese dioxide and increase the chlorine doping amount in manganese dioxide. The method has a simple process, low cost, and is easy to mass produce. The prepared chlorine-doped manganese oxide has stable and efficient catalytic performance as an ozone decomposition catalyst, and can remove ozone from the air even at room temperature and high humidity, and convert ozone into safe and harmless oxygen.

[0022] Other features and advantages of the present application will be described in detail in the subsequent detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is the X-ray diffraction pattern of the chlorine-doped manganese oxide prepared in Examples 1-5;

[0024] Figure 2 The scanning electron microscope images, diffraction images and high-resolution transmission electron microscope images of the chlorine-doped manganese oxide prepared in Examples 1-5;

[0025] Figure 3 is a Fourier transform infrared spectrum of the chlorine-doped manganese oxide prepared in Examples 6-10;

[0026] Figure 4 The nitrogen adsorption-desorption curves of the chlorine-doped manganese oxides prepared in Examples 11-15 at 77K;

[0027] Figure 5 The pore size distribution diagram of the chlorine-doped manganese oxide prepared in Examples 11-15;

[0028] Figure 6 The ozone conversion rate at different reaction times during the catalytic decomposition of ozone by the chlorine-doped manganese oxide prepared in Example 16;

[0029] Figure 7 This is the in-situ infrared test spectrum of the chlorine-doped manganese oxide prepared in Example 1 and Example 17 under high humidity and high concentration ozone conditions. DETAILED DESCRIPTION

[0030] In order to facilitate understanding of the present application, the present application will be described more fully below with reference to the relevant drawings. The present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present application more thorough and comprehensive.

[0031] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art to which the present application belongs. The terms used herein in the specification of the present application are only for the purpose of describing specific embodiments and are not intended to limit the present application. The term "and / or" used herein includes any and all combinations of one or more related listed items. "Multiple" means more than two, such as two, three, four, etc. "At least one" means one or more than two, such as one, two, three, four, etc.

[0032] When a numerical range is disclosed herein, the above range is considered to be continuous and includes the minimum and maximum values ​​of the range, as well as every value between such minimum and maximum values. Further, when a range refers to an integer, every integer between the minimum and maximum values ​​of the range is included. In addition, when multiple ranges are provided to describe features or characteristics, the ranges can be combined. In other words, unless otherwise indicated, all ranges disclosed herein should be understood to include any and all subranges included therein.

[0033] The inventors of this application have found that among many metal oxides, manganese dioxide has a good potential for catalytic decomposition of ozone, among which the oxygen defects with a high concentration in manganese dioxide belong to common active sites for ozone catalytic reactions, which can remove ozone well; however, when there is water vapor in the air, water molecules will competitively adsorb on the oxygen defect positions in manganese dioxide, and the oxygen defects of the catalyst will be occupied by water molecules or the surface of the catalyst will be hydroxylated, resulting in reduced catalyst activity or even gradual deactivation. In order to ensure that the manganese dioxide catalyst can be used efficiently and stably for a long time under room temperature and humid conditions, it is very necessary to develop a method that can significantly improve the moisture resistance of manganese dioxide oxygen vacancies and is easy to implement. Accordingly, this application is proposed.

[0034] In a first aspect, the present application provides a method for preparing chlorine-doped manganese oxide, the preparation method comprising: subjecting permanganate and chloride to a hydrothermal synthesis reaction.

[0035] In the present application, the temperature of the hydrothermal synthesis reaction is 100°C-200°C, for example, 100°C, 110°C, 115°C, 118°C, 120°C, 122°C, 125°C, 130°C, 132°C, 135°C, 137°C, 140°C, 143°C, 145°C, 150°C, 155°C, 160°C, 170°C, 180°C, 190°C or 200°C.

[0036] In the present application, the time of the hydrothermal synthesis reaction is 10h-40h, for example, 10h, 11h, 11.5h, 12h, 13h, 14h, 15h, 16h, 17h, 18h, 19h, 21h, 22h, 23h, 24h, 25h, 26h, 27h, 28h, 29h, 30h, 31h, 32h, 32.5h, 33h, 34h, 35h, 36h, 37h, 38h, 39h or 40h.

[0037] In some embodiments, the temperature of the hydrothermal synthesis reaction is 100° C.-150° C., and the reaction time is 12 h-36 h, so that the chlorine doping amount can be further increased while generating birnessite-type manganese dioxide.

[0038] In the present application, the permanganate can be selected from various soluble permanganates, as long as manganese dioxide is formed through a hydrothermal reaction. In some embodiments, the permanganate includes one or more of potassium permanganate, sodium permanganate and ammonium permanganate. Preferably, the permanganate is potassium permanganate.

[0039] In this application, the chloride refers to a substance that dissolves in water to provide chloride ions (Cl - ), preferably the chloride comprises ammonium chloride.

[0040] In some embodiments, the molar ratio of the permanganate to the chloride is 1:(0.5-1.5), for example, 1:0.5, 1:0.75, 1:0.8, 1:9, 1:1, 1:1.25, 1:1.3, 1:1.4, 1:1.5, 1:1.75, 1:1.8 or 1:2. Preferably, the molar ratio of the permanganate to the chloride is 1:(0.9-1.2).

[0041] In some embodiments, the preparation method comprises the following steps:

[0042] S1: dissolving the permanganate and the chloride in water to obtain a reaction solution;

[0043] S2: placing the reaction solution in a hydrothermal kettle to carry out the hydrothermal synthesis reaction.

[0044] In step S1, in the reaction solution, the total concentration of the permanganate and the chloride is 0.1mol / L-10mol / L, for example, 0.1mol / L, 0.15mol / L, 0.175mol / L, 0.18mol / L, 0.19mol / L, 0.2mol / L, 0.22mol / L, 0.25mol / L, 0.3mol / L, 0.4mol / L, 0.5mol / L, 1mol / L, 2mol / L, 2.5mol / L, 2.7mol / L, 3mol / L, etc.

[0045] In step S1, the permanganate and the chloride are dissolved in water to form a homogeneous solution. Optionally, the dissolution process includes: firstly dissolving the permanganate in water to form an aqueous solution of permanganate, and then adding the chloride (such as ammonium chloride) to the aqueous solution and stirring uniformly.

[0046] In some embodiments, after performing the hydrothermal synthesis reaction, the preparation method further comprises:

[0047] S3: The obtained reaction product is subjected to solid-liquid separation, washing and drying.

[0048] In step S3, the solid-liquid separation method may include suction filtration. The washing may be performed with deionized water.

[0049] In step S3, the drying temperature may be 60° C.-200° C., for example, 60° C., 70° C., 80° C., 90° C., 95° C., 100° C., 105° C., 108° C., 110° C., 115° C., 120° C., 125° C., 130° C., 140° C., 150° C., 160° C., 170° C., 180° C., 188° C., 190° C. or 200° C. In order to improve the pore structure of the catalyst while improving the drying efficiency, preferably, the drying temperature is 100° C.-130° C.

[0050] In step S3, the drying time can be 6h-24h, for example, 8h, 9h, 10h, 11h, 12h, 15h, 16h, 18h, 19h, 20h, 21h, 22h, 23h, 24h.

[0051] In a second aspect, the present application provides a chlorine-doped manganese oxide prepared by the preparation method. The chlorine-doped manganese oxide prepared in the present application is a chlorine-doped birnessite-type manganese dioxide.

[0052] In some embodiments, the mass content of chlorine in the chlorine-doped manganese oxide is 0.06%-2.20%. Preferably, the mass content of chlorine in the chlorine-doped manganese oxide is 1.00%-2.20%. The chlorine content is obtained by anion chromatography test.

[0053] In some embodiments, the average pore size of the chlorine-doped manganese oxide is 4.8um-7.2nm, preferably 6nm-7.2nm; the specific surface area of ​​the chlorine-doped manganese oxide is 270m 2 / g-350m 2 / g, preferably 300m 2 / g-330m 2 The average pore size and specific surface area were measured using the nitrogen adsorption BET method.

[0054] In a third aspect, the present application provides the use of the chlorine-doped manganese oxide as an ozone decomposition catalyst. The chlorine-doped manganese oxide prepared by the preparation method of the present application has excellent catalytic decomposition performance of ozone, has a high conversion rate of ozone, and the catalyst has high stability.

[0055] In a fourth aspect, the present application provides a method for decomposing ozone, the method comprising: subjecting an ozone-containing gas to a decomposition reaction in the presence of the chlorine-doped manganese oxide.

[0056] In some embodiments, the volume concentration of ozone in the ozone-containing gas is 50ppm-200ppm, for example 100ppm; the relative humidity is 0%-90%, for example 10%, 20%, 25%, 30%, 40%, 50%, 80%, 85%, 90%, etc.

[0057] In the present application, the ozone-containing gas is, for example, air.

[0058] In some embodiments, the reaction conditions of the decomposition reaction include: the mass space velocity (WHSV) of the gas is 300 L·g -1 ·h -1 -1200L·g -1 ·h -1 , for example 600L·g -1 ·h -1 , the reaction temperature is 15°C-40°C, for example 25°C.

[0059] The present application will be described below in conjunction with specific embodiments, but it should be understood that the present application is not limited to the following embodiments.

[0060] Example 1

[0061] Potassium permanganate (1.27 g, 8 mmol) was added to 80 mL of deionized water and stirred until dissolved to obtain a potassium permanganate solution. Ammonium chloride (0.21 g, 4 mmol) was added to the above potassium permanganate solution and stirred to dissolve to obtain a reaction solution.

[0062] After the reaction solution was poured into a hydrothermal autoclave, it was placed in an oven for hydrothermal reaction at 130°C for 30 hours. The product in the hydrothermal autoclave was then filtered, and the obtained solid was washed with 1.5L of deionized water. The product was then dried at 105°C for 12 hours to obtain chlorine-doped manganese oxide, which was recorded as Cat-1.

[0063] Embodiment 2-5

[0064] Chlorine-doped manganese oxides were prepared according to the method of Example 1, except that in Examples 2-5, the amount of ammonium chloride was adjusted to 0.32 g (6 mmol), 0.43 g (8 mmol), 0.54 g (10 mmol) and 0.64 g (12 mmol), respectively. The prepared chlorine-doped manganese oxides were respectively recorded as Cat-2, Cat-3, Cat-4 and Cat-5.

[0065] The products of Examples 1-5 were tested by anion chromatography, where the mass fraction of chlorine in Cat-1 was 0.06%, the mass fraction of chlorine in Cat-2 was 0.48%, the mass fraction of chlorine in Cat-3 was 1.00%, the mass fraction of chlorine in Cat-4 was 1.60%, and the mass of chlorine in Cat-5 was 2.20%. It can be seen that the chlorine content in the chlorine-doped manganese oxide increased significantly with the increase in the amount of ammonium chloride added through ion chromatography.

[0066] Figure 1 The X-ray diffraction patterns of Cat-1 (MnO2-0.5), Cat-2 (MnO2-0.75), Cat-3 (MnO2-0.1), Cat-4 (MnO2-1.25) and Cat-5 (MnO2-1.5) are shown in the figure. It can be seen from the figure that Cat-1 to Cat-5 are consistent with the XRD standard card (JCPDS 80-1098) of birnessite-type manganese dioxide, indicating that the products prepared in Examples 1-5 are birnessite-type manganese dioxide; in addition, with the increase of the amount of ammonium chloride added, the diffraction peak of the 001 plane on the XRD spectrum gradually decreases, indicating that the chlorine element is successfully doped into the manganese dioxide crystal phase.

[0067] Figure 2 The scanning electron microscope (SEM), diffraction photographs and high-resolution transmission electron microscope (TEM) photographs of the manganese dioxide catalysts of Examples 1-5 are shown; wherein,

[0068] (a), (b), (c), (d) and (e) are SEM images of the samples of Examples 1-5 at different magnifications. From the field emission images, it can be seen that as the amount of ammonium chloride added increases, the size of the chlorine-doped manganese oxide continues to decrease and the accumulation pores increase, which is conducive to the adsorption of gas on the catalyst and the desorption of intermediate products;

[0069] (f) and (g) are the electron diffraction patterns of the samples of Examples 1 and 4, respectively. The diffraction photos clearly show that the crystallinity of the catalyst is significantly reduced as the doping of chlorine increases;

[0070] (h) and (i) are high-resolution TEM images of the sample (Cat-1) of Example 1, and (j) and (k) are high-resolution TEM images of the sample (Cat-4) of Example 4. The TEM images show that the exposed surface of the product after chlorine doping is the 001 surface, and the crystallinity becomes poor, which indicates that the catalyst may be caused by a significant increase in oxygen defects.

[0071] Example 6

[0072] Potassium permanganate (1.58 g, 10 mmol) was added to 70 mL of deionized water and stirred until dissolved to obtain a potassium permanganate solution. Ammonium chloride (0.21 g, 4 mmol) was added to the above potassium permanganate solution and stirred to dissolve to obtain a reaction solution.

[0073] The reaction solution was poured into a hydrothermal autoclave and placed in an oven for hydrothermal reaction at 120°C for 36 hours. The product in the hydrothermal autoclave was then filtered and the obtained solid was washed with 1.5L of deionized water. The product was then dried at 105°C for 12 hours to obtain chlorine-doped manganese oxide, which was recorded as Cat-6.

[0074] Examples 7-10

[0075] Chlorine-doped manganese oxides were prepared according to the method of Example 6, except that in Examples 7-10, the amount of ammonium chloride was adjusted to 0.32 g (6 mmol), 0.43 g (8 mmol), 0.54 g (10 mmol) and 0.64 g (12 mmol), respectively. The prepared chlorine-doped manganese oxides were respectively recorded as Cat-7, Cat-8, Cat-9 and Cat-10.

[0076] Figure 3 The Fourier transform infrared spectra of Cat-6 to Cat-10 of Examples 6-10 are shown in FIG. 1 , wherein 1050 cm -1 and 1370cm -1 All belong to Mn-OH species; Figure 3 It can be seen that with the increase of ammonium chloride dosage, the Mn-OH peak intensity of the sample decreases, indicating that the Mn-OH species decreases with chlorine doping, indicating that the increase in the amount of chlorine doping can significantly reduce the water dissociation adsorption on the catalyst surface, indicating that chlorine doping can protect oxygen defects from being occupied by hydroxyl groups that are dissociated and adsorbed by water.

[0077] Comparative Example 1

[0078] Potassium permanganate (1.58 g, 10 mmol) was added to 70 mL of deionized water and stirred until dissolved to obtain a potassium permanganate solution. Ammonium chloride (0.64 g, 12 mmol) was added to the above potassium permanganate solution and stirred to dissolve to obtain a reaction solution.

[0079] After the reaction solution was poured into a hydrothermal autoclave, it was placed in an oven for hydrothermal reaction at 120°C for 50 hours. The product in the hydrothermal autoclave was then filtered, and the obtained solid was washed with 1.5L of deionized water. The product was then dried at 105°C for 12 hours to obtain chlorine-doped manganese oxide, which was recorded as Cat-D1.

[0080] Comparative Example 2

[0081] Potassium permanganate (1.58 g, 10 mmol) was added to 70 mL of deionized water and stirred until dissolved to obtain a potassium permanganate solution. Ammonium chloride (0.64 g, 12 mmol) was added to the above potassium permanganate solution and stirred to dissolve to obtain a reaction solution.

[0082] After the reaction solution was poured into a hydrothermal autoclave, it was placed in an oven for hydrothermal reaction at 280°C for 30 hours. The product in the hydrothermal autoclave was then filtered, and the obtained solid was washed with 1.5L of deionized water. The product was then dried at 105°C for 12 hours to obtain chlorine-doped manganese oxide, which was recorded as Cat-D2.

[0083] Embodiment 11

[0084] Potassium permanganate (1.50 g, 9.5 mmol) was added to 75 mL of deionized water and stirred until dissolved to obtain a potassium permanganate solution. Ammonium chloride (0.21 g, 4 mmol) was added to the above potassium permanganate solution and stirred to dissolve to obtain a reaction solution.

[0085] The reaction solution was poured into a hydrothermal autoclave and placed in an oven for hydrothermal reaction at 120°C for 30 hours. The product in the hydrothermal autoclave was then filtered and the obtained solid was washed with 1.5 L of deionized water. The product was then dried at 105°C for 12 hours to obtain chlorine-doped manganese oxide, which was recorded as Cat-11.

[0086] Examples 12-15

[0087] Chlorine-doped manganese oxides were prepared according to the method of Example 11, except that in Examples 12-15, the amount of ammonium chloride was adjusted to 0.32 g (6 mmol), 0.43 g (8 mmol), 0.54 g (10 mmol) and 0.64 g (12 mmol), respectively. The prepared chlorine-doped manganese oxides were respectively recorded as Cat-12, Cat-13, Cat-14 and Cat-15.

[0088] Figure 4 The nitrogen adsorption-desorption curves of the chlorine-doped manganese oxides Cat-11 to Cat-15 of Examples 11-15 at 77 K. The specific surface areas of Cat-11 to Cat-15 calculated by the BET method are 84 m 2 / g, 208m 2 / g, 225m 2 / g, 312m 2 / g, 278m 2 / g. Figure 5The pore size distribution diagram of the Cat-11 to Cat-15 catalysts of Examples 11-15, the average pore sizes are 4.9 nm, 6.1 nm, 7.03 nm, 7.03 nm and 7.03 nm, respectively, indicating that chlorine doping can increase the average pore size of the catalyst and weaken the water condensation effect in the catalyst pores. It can be seen that in the method of the present application, increasing the chlorine doping amount can increase the specific surface area of ​​the catalyst and enhance the hydrophobicity of the catalyst.

[0089] Example 16

[0090] Potassium permanganate (1.27 g, 8 mmol) was added to 80 mL of deionized water and stirred until dissolved to obtain a potassium permanganate solution. Ammonium chloride (0.54 g, 10 mmol) was added to the above potassium permanganate solution and stirred to dissolve to obtain a reaction solution.

[0091] The reaction solution was poured into a hydrothermal autoclave and placed in an oven for hydrothermal reaction at 130°C for 24 hours. The product in the hydrothermal autoclave was then filtered and the obtained solid was washed with 1.5L of deionized water. The product was then dried at 100°C for 15 hours to obtain chlorine-doped manganese oxide, which was recorded as Cat-16.

[0092] Embodiment 17

[0093] Potassium permanganate (1.27 g, 8 mmol) was added to 60 mL of deionized water and stirred until dissolved to obtain a potassium permanganate solution. Ammonium chloride (0.48 g, 9 mmol) was added to the above potassium permanganate solution and stirred to dissolve to obtain a reaction solution.

[0094] The reaction solution was poured into a hydrothermal autoclave and placed in an oven for hydrothermal reaction at 120°C for 12 hours. The product in the hydrothermal autoclave was then filtered and the obtained solid was washed with 1.5 L of deionized water. The product was then dried at 105°C for 16 hours to obtain chlorine-doped manganese oxide, which was recorded as Cat-17.

[0095] Test Case

[0096] Pure oxygen is passed through a 185nm ultraviolet lamp to produce a mixture of O2 and O3. The sample is placed in a reactor and passed through a quartz tube filled with a catalyst. A portion of the gas goes into an ozone analyzer to measure the ozone concentration, and a portion of the exhaust gas is treated. The ozone conversion rate is calculated according to the following formula:

[0097] Ozone conversion rate (%) = (C o -C t ) / C o ×100

[0098] The reaction conditions were: inlet ozone concentration 100 ppm, temperature 25°C, relative humidity (RH) 90%, mass space velocity 600 L·g-1 ·h -1 The catalyst (chlorine-doped manganese oxide) used and the ozone conversion rate when the reaction was stably operated for 30 hours and 100 hours are shown in Table 1:

[0099] Table 1

[0100]

[0101]

[0102] As can be seen from Table 1, the chlorine-doped manganese oxide prepared in the present application has a high catalytic activity, and as the reaction time runs, the conversion rate decreases slightly, indicating that it also has a high catalytic stability; and by increasing the chlorine content in the manganese dioxide, the ozone decomposition effect can be significantly improved.

[0103] In addition, by comparing Cat-10 with Cat-D1 and Cat-D2, it can be seen that under the condition of the same feed amount, too long reaction time and too high reaction temperature will lead to a decrease in catalytic performance. The reason is that when the hydrothermal reaction time is too long, it will lead to the loss of active sites; when the hydrothermal reaction temperature is too high, it will cause the birnessite to transform into a-MnO2 with poorer effect.

[0104] Figure 6 The curve diagram is drawn of the ozone conversion rate of the catalyst Cat-16 in Example 16 at different times under continuous reaction operation. Figure 6 It can be seen that under the above high space velocity and high humidity conditions, Cat-16 can still maintain very good catalytic performance (conversion rate is above 90%) within 100 hours, which shows that chlorine-doped manganese dioxide has very good stability and high efficiency.

[0105] Taking the chlorine-doped manganese oxides prepared in Example 1 and Example 17 as examples, in-situ infrared tests were conducted on them as ozone catalysts under high humidity and high concentration (humidity: 90%, ozone concentration 100 ppm) ozone conditions. The results are as follows: Figure 7 As shown in Figure 2, the surface of Cat-1 is not only significantly hydroxylated, but also accumulates a large amount of intermediates (O2 2- , O 3- and O 2- )(See Figure 7 (a)), there is basically no accumulation of intermediate products on the surface of Cat-17 doped with more chlorine, and the water adsorption effect is significantly weakened (see Figure 7 (b)), which indicates that Cat-17 has oxygen vacancies that are resistant to moisture and not prone to accumulating intermediate products.

[0106] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0107] The above-described embodiments only express several specific implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the present invention. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the attached claims.

Claims

1. A method for decomposing ozone, characterized in that: The method comprises: in the presence of chlorine-doped manganese oxide, subjecting ozone-containing gas to an ozone decomposition reaction, wherein the preparation method of the chlorine-doped manganese oxide comprises the following steps: Dissolving permanganate and chloride in water to obtain a reaction solution, wherein the total concentration of the permanganate and the chloride in the reaction solution is 0.15 mol / L - 10 mol / L, and the molar ratio of the permanganate to the chloride is 1:(0.5 - 1.5); The reaction solution is subjected to a hydrothermal synthesis reaction to obtain chlorine-doped manganese oxide, wherein the temperature of the hydrothermal synthesis reaction is 100° C. to 200° C. and the reaction time is 10 h to 40 h; The chlorine-doped manganese oxide is chlorine-doped birnessite-type manganese dioxide, the chlorine doping in the chlorine-doped manganese oxide is used to protect oxygen defects from being occupied by hydroxyl groups adsorbed by water dissociation, and the mass fraction of chlorine in the chlorine-doped manganese oxide is 0.06%-2.20%.

2. The method for decomposing ozone according to claim 1, characterized in that: The permanganate includes one or more of potassium permanganate, sodium permanganate and ammonium permanganate.

3. The method for decomposing ozone according to claim 1, characterized in that: The chloride includes ammonium chloride.

4. The method for decomposing ozone according to claim 1, characterized in that: The molar ratio of the permanganate to the chloride is 1:(0.9 - 1.2).

5. The method for decomposing ozone according to claim 1, characterized in that: The preparation method further comprises: after the hydrothermal synthesis reaction, solid-liquid separation, washing and drying of the obtained reaction product.

6. The method for decomposing ozone according to claim 5, characterized in that: The drying temperature is 60°C - 200°C, and the drying time is 6 h - 24 h.

7. The method for decomposing ozone according to any one of claims 1 to 6, characterized in that: The average pore size of the chlorine-doped manganese oxide is 4.8 nm to 7.2 nm, and the specific surface area is 270 m 2 / g - 350 m 2 / g.

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