Normal-temperature high-humidity ozone decomposition catalyst, and preparation method and application thereof

Abstract

The present application relates to a kind of preparation method of ambient temperature high humidity ozone decomposition catalyst and its application, the catalyst is synthesized by simple rheological phase method, mainly using Co and Mn to form double metal oxide.The optimal performance catalyst obtained can realize the removal efficiency of nearly 100% to ozone under ambient temperature high humidity condition, and keep stable and efficient operation at least 100h.The method is not only energy-efficient, short steps, and green pollution-free, except water does not use any surfactant or template and other polluting solvents.The catalyst can be widely used in various low concentration ozone pollution sources, such as air purifier, sterilization cabinet, printer, and ultraviolet photolysis and other end ozone decomposition.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of catalysts, and relates to a preparation method and application of an ozone decomposition catalyst. BACKGROUND

[0002] The over-standard near-surface ozone concentration has always posed a threat to human health, especially in urban areas. Outdoor ozone is mainly produced by the photochemical reaction of nitrogen oxides and volatile organic pollutants (VOCs) in the air under sunlight. Ozone has excellent bactericidal and disinfecting properties, and the inactivation reaction is rapid. The good bactericidal and disinfecting effect makes ozone have a wide range of uses in the medical and health fields. Indoor ozone comes from the exchange of indoor and outdoor air, and some emission sources include copying machines, laser printers, ultraviolet lamps and ozone disinfectants. The widespread use of electrical appliances in daily life makes ozone one of the main air pollutants in modern society. Although ozone is a strong oxidizing agent with strong reactivity, it is relatively stable by itself and almost does not spontaneously decompose into oxygen at the concentration (ppb level) usually encountered in the environment. In addition, ozone can have adverse effects on the growth of plants, insects and soil microbial communities, threatening terrestrial ecosystems and ecological diversity. In addition, indoor ozone sources can also cause secondary organic aerosol pollution, endangering human health. A large number of studies have shown that long-term exposure to air containing trace amounts of ozone can pose a potential risk of respiratory and cardiovascular diseases and even death to the human body. In addition, long-term inhalation of ozone and other chemical substances to produce secondary pollutants can even cause irreversible damage to the DNA of living organisms. However, in the past few years, the occurrence of severe ozone pollution in the warm season has become more frequent. Therefore, it is urgent to develop an efficient and environmentally friendly ozone elimination method.

[0003] Ozone decomposition methods mainly include thermal decomposition, activated carbon method, liquid absorption method and catalytic decomposition method. The thermal decomposition method is usually suitable for high-concentration industrial waste gas treatment, and the required conditions are harsh, usually requiring high temperatures above 400℃; the activated carbon method is suitable for low-concentration ozone decomposition, but it is easy to be inactivated and has poor water resistance; the liquid absorption method will have waste liquid leading to secondary pollution and other problems; the catalytic decomposition method can better make up for the shortcomings of the above methods, and has the advantages of low energy consumption, rapid reaction, high treatment efficiency and the like. Therefore, the catalytic decomposition of ozone is the key to controlling ozone pollution. The key of the catalytic decomposition technology lies in the performance of the catalyst, therefore, it is urgent to develop a normal-temperature and high-humidity-resistant ozone decomposition catalyst.

[0004] CN117861681A discloses a catalyst for ozone decomposition, a preparation method and applications thereof. The catalyst is a layered metal hydroxide with a hydrotalcite structure. The preparation method comprises: obtaining a positive electrode sheet of a waste lithium manganese oxide battery and crushing it to obtain a positive electrode active powder; the positive electrode active powder is treated with a leaching agent and a reducing agent to obtain a leaching solution with a volume ratio of (90-110):(4-6), and then filtered after being treated at 60-80℃ for 1-5h; deionized water is added to the filtrate, the pH is adjusted to 3-4, and then a nickel metal salt is added to the filtrate, wherein the molar ratio of nickel element, manganese element and copper element is (2.5-3.5):1:(0.02-0.05); finally, H2O2 solution and urea are added, heated at 110-130℃ for 11-13h, and then dried at 55-65℃ for 6-12h to obtain the ozone decomposition catalyst.

[0005] CN115417941A discloses a catalyst suitable for ozone decomposition in atmospheric environment and applications thereof. The preparation method comprises: mixing azobisisobutyronitrile, ethylene glycol dimethacrylate and toluene in a certain proportion, and carrying out precipitation polymerization reaction under the condition of oxygen isolation and 60-70℃ temperature, and the reaction time is 5-20h; after the reaction is completed, most of the organic solution is removed by vacuum filtration, and the obtained polymer (i.e. polyethylene glycol dimethacrylate) solid is transferred to a vacuum drying oven for drying to obtain the catalyst.

[0006] CN116726911A discloses a Mn5O8 ozone normal temperature decomposition catalyst and a preparation method thereof. The preparation method comprises: mixing potassium permanganate salt and manganate salt with solid organic acid, solid-phase grinding for 1-5min, heating at 60-120℃ for 0.5-2h to obtain a fluffy precursor; after cooling, adding it to distilled water, stirring uniformly, heating at 80-200℃ for 0.5-3h for activation, and then filtering, washing and drying to obtain the Mn5O8 ozone normal temperature decomposition catalyst.

[0007] Manganese oxides have multiple polymorphs, and are considered to be the most potential catalysts for ozone decomposition due to their different crystal structures, different manganese valence states, low cost and easy production. Although manganese oxides have high activity in the field of ozone catalysis / decomposition and are widely used, their moisture resistance is poor, and their catalytic activity under high humidity conditions is not satisfactory, which hinders their industrial application process. Therefore, improving the water resistance of manganese-based catalysts is the key to solving the application of ozone decomposition catalysts. SUMMARY

[0008] The technical problem to be solved by the present application is to overcome the shortcomings of the prior art and provide a preparation method of a normal temperature high-humidity-resistant ozone decomposition catalyst. The catalyst can achieve high-efficiency decomposition of ozone at normal temperature, and the decomposition rate reaches 100%, and has the advantages of long catalytic life and high humidity resistance.

[0009] To solve the above technical problems, the technical scheme adopted by the present application is:

[0010] In a first aspect, the present application provides a preparation method of a normal-temperature high-humidity ozone decomposition catalyst, which comprises the following steps:

[0011] (1) grinding cobalt nitrate and a chelating agent in a mortar, then adding a manganese element nitrate precursor, and adjusting to a rheological phase for further grinding;

[0012] (2) during the grinding process, as the liquid water content decreases, a small amount of solvent is added for sufficient grinding to obtain a rheological phase mixed metal solution;

[0013] (3) transferring the rheological phase mixed metal solution obtained by grinding to a reaction tank, heating and activating in an oven, and then sequentially performing solid-liquid separation, washing, drying, and calcination to obtain the catalyst.

[0014] The present application adopts a simple rheological phase method to synthesize a manganese-cobalt bimetallic catalyst. By grinding, a chelation reaction occurs between the metal salt and the chelating agent, a solvent is added to make the mixed solution in a rheological phase, and then heating and activation are performed to improve the catalytic activity and stability of the prepared catalyst. This method is not only energy-saving and efficient, but also simple in steps and green and pollution-free, and no surfactant or template or other polluting solvents are used except water.

[0015] Preferably, the chelating agent in step (1) is oxalic acid dihydrate.

[0016] Preferably, in step (1), the manganese element nitrate precursor is a manganese nitrate solution with a mass percentage concentration of 50%.

[0017] Preferably, the molar ratio of the cobalt nitrate to the chelating agent oxalic acid dihydrate in step (1) is (0.8-1.2):1.

[0018] Preferably, the solvent in step (2) is deionized water.

[0019] Preferably, the heating and activation conditions of the rheological phase mixed metal solution in step (3) are 100-110℃ for 7-9h.

[0020] Preferably, the molar ratio of cobalt element to manganese element in the rheological phase mixed metal solution is 1:(4.5-5.5).

[0021] Preferably, the drying conditions are 100-110℃ for 11-13h.

[0022] Preferably, the calcination conditions are 450-550℃ for 5-7h.

[0023] In a second aspect, the present application provides a catalyst for ozone decomposition at room temperature and under high humidity, which is a bimetallic oxide with a cubic square structure, wherein the bimetals are cobalt and manganese respectively; and the specific bimetallic structure of the catalyst is MnCo2O4. 4.5 The specific surface area of the catalyst reaches 113.35 m2 / g. 2 / g.

[0024] The catalyst with the optimal performance obtained by the present application can achieve an ozone removal efficiency close to 100% under the condition of room temperature and high humidity, and can maintain stable and efficient operation for at least 100 hours.

[0025] In a third aspect, the present application provides an application of the catalyst for ozone decomposition at room temperature and under high humidity, which is used for catalytic decomposition of ozone. The present application can be applied to various low-concentration ozone pollution sources, such as air purifiers, sterilization cabinets, printers, and end ozone decomposition by ultraviolet photolysis.

[0026] Compared with the prior art, the present application has the following beneficial effects:

[0027] (1) The catalyst is prepared by the rheological phase method, and the preparation process is simple and easy to realize industrialization;

[0028] (2) The active components of the present application are all non-noble metals, and the raw materials are cheap, which greatly reduces the production cost;

[0029] (3) The catalyst has a unique cubic square structure, which can ensure the ozone decomposition rate while improving the stability and humidity resistance of the catalyst. The ozone decomposition rate can be ensured to be close to 100% under the conditions of 100h stability test and 4vol% H2O humidity test;

[0030] (4) The present application does not require high-temperature heating, high-pressure and other complex reaction conditions, and the reaction can be completed at room temperature, which is safer;

[0031] (5) The present application is not only energy-saving, efficient and simple, but also more environmentally friendly without using any surfactants or templates and other polluting solvents. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 FIG. 1 is an XRD pattern of the catalyst for ozone decomposition at room temperature and under high humidity described in Example 1.

[0033] Figure 2 FIG. 2 is an SEM pattern of the catalyst for ozone decomposition at room temperature and under high humidity described in Example 1.

[0034] Figure 3 FIG. 3 is an activity comparison diagram of the ozone decomposition catalysts prepared in Examples 1-5 under the condition of room temperature and dryness.

[0035] Figure 4 is the activity comparison chart of the ozone decomposition catalysts prepared in Examples 1-5 under the condition of normal temperature and 4vol% H2O.

[0036] Figure 5 is the ozone detection test paper chart of the ozone decomposition catalysts prepared in Examples 1-5 after testing under the condition of 4vol% H2O.

[0037] Figure 6 is the stability evaluation chart of the ozone decomposition catalyst prepared in Example 1 under the conditions of dry and 4vol% H2O respectively for 100h.

[0038] Figure 7 is the XRD chart of the ozone decomposition catalysts prepared in Examples 1 and 6.

[0039] Figure 8 is the SEM chart of the ozone decomposition catalysts prepared in Examples 1-10. DETAILED DESCRIPTION

[0040] The technical solutions in the embodiments of the present application will be clearly and completely described below in combination with the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. The following embodiments are only used to more clearly illustrate the technical solutions of the present application, and cannot be used to limit the protection scope of the present application.

[0041] Example 1

[0042] The method is a rheological phase method, and the preparation process is as follows:

[0043] 1.80g of cobalt nitrate and 2.478g of oxalic acid dihydrate are weighed and placed in a mortar for grinding for 10min, 7.2mL of Mn element nitrate precursor is added, and the rheological phase is adjusted and ground; during grinding, deionized water is continuously added as the liquid water content decreases, and grinding is performed sufficiently. The viscous paste obtained by grinding is transferred into a polytetrafluoroethylene reaction tank, heated and activated at 105℃ for 8h; after cooling, the solution in the tank is transferred to a beaker, and after solid-liquid separation, it is dried at 105℃ for 12h, and then placed in a muffle furnace and calcined at 500℃ for 6h to obtain MnCo2O4. 4.5 ozone decomposition catalyst.

[0044] Example 2

[0045] The method is a rheological phase method, and the preparation process is as follows:

[0046] Take 2.69 g of cerium nitrate and 2.478 g of oxalic acid dihydrate, put them in a mortar and grind for 10 min, add 7.2 mL of Mn element nitrate precursor, adjust to rheological phase and continue to grind; continue to add deionized water during grinding as the liquid water content decreases, grind thoroughly, transfer the thick paste obtained by grinding into a polytetrafluoroethylene reaction tank, heat and activate at 105°C for 8h; after cooling, transfer the solution in the tank to a beaker, separate the solid and liquid, dry at 105°C for 12h, and then put it into a muffle furnace and calcine at 500°C for 6h to obtain a MnCe ozone decomposition catalyst.

[0047] Example 3

[0048] The method is a rheological phase method, and the preparation process is as follows:

[0049] Take 1.80 g of nickel nitrate and 2.478 g of oxalic acid dihydrate, put them in a mortar and grind for 10 min, add 7.2 mL of Mn element nitrate precursor, adjust to rheological phase and continue to grind; continue to add deionized water during grinding as the liquid water content decreases, grind thoroughly, transfer the thick paste obtained by grinding into a polytetrafluoroethylene reaction tank, heat and activate at 105°C for 8h; after cooling, transfer the solution in the tank to a beaker, separate the solid and liquid, dry at 105°C for 12h, and then put it into a muffle furnace and calcine at 500°C for 6h to obtain a MnNi ozone decomposition catalyst.

[0050] Example 4

[0051] The method is a rheological phase method, and the preparation process is as follows:

[0052] Take 1.50 g of copper nitrate and 2.478 g of oxalic acid dihydrate, put them in a mortar and grind for 10 min, add 7.2 mL of Mn element nitrate precursor, adjust to rheological phase and continue to grind; continue to add deionized water during grinding as the liquid water content decreases, grind thoroughly, transfer the thick paste obtained by grinding into a polytetrafluoroethylene reaction tank, heat and activate at 105°C for 8h; after cooling, transfer the solution in the tank to a beaker, separate the solid and liquid, dry at 105°C for 12h, and then put it into a muffle furnace and calcine at 500°C for 6h to obtain a MnCu ozone decomposition catalyst.

[0053] Example 5

[0054] The method is a rheological phase method, and the preparation process is as follows:

[0055] Take 2.478 g of oxalic acid dihydrate, mix it with 7.2 mL of Mn element nitrate precursor into rheological phase grinding; continue to add deionized water during grinding as the liquid water content decreases, grind thoroughly, transfer the viscous paste obtained by grinding into a polytetrafluoroethylene reaction tank, heat and activate at 105°C for 8h; after cooling, transfer the solution in the tank to a beaker, separate the solid and liquid, dry at 105°C for 12h, and then put it into a muffle furnace and calcine at 500°C for 6h to obtain a Mn ozone decomposition catalyst.

[0056] Example 6

[0057] The catalyst is the sample of the catalyst obtained in Example 1 after testing under the condition of 4vol% H2O for 15h. The test conditions are: total gas flow is 1L / min, 1.5ppm O3, 4vol% H2O, catalyst dosage is 0.04g, reaction space velocity is 1500L / (g·h) -1 , test temperature is room temperature.

[0058] Example 7

[0059] The catalyst is the sample of the catalyst obtained in Example 2 after testing under the condition of 4vol% H2O for 15h. The test conditions are: total gas flow is 1L / min, 1.5ppm O3, 4vol% H2O, catalyst dosage is 0.04g, reaction space velocity is 1500L / (g·h) -1 , test temperature is room temperature.

[0060] Example 8

[0061] The catalyst is the sample of the catalyst obtained in Example 3 after testing under the condition of 4vol% H2O for 15h. The test conditions are: total gas flow is 1L / min, 1.5ppm O3, 4vol% H2O, catalyst dosage is 0.04g, reaction space velocity is 1500L / (g·h) -1 , test temperature is room temperature.

[0062] Example 9

[0063] The catalyst is the sample of the catalyst obtained in Example 4 after testing under the condition of 4vol% H2O for 15h. The test conditions are: total gas flow is 1L / min, 1.5ppm O3, 4vol% H2O, catalyst dosage is 0.04g, reaction space velocity is 1500L / (g·h) -1 , test temperature is room temperature.

[0064] Example 10

[0065] The catalyst is the sample of the catalyst prepared in Example 5 after 15h testing under 4vol% H2O condition. The testing condition is: total gas flow 1L / min, 1.5ppm O3, 4vol% H2O, catalyst dosage 0.04g, reaction space velocity 1500L / (g·h) -1 , testing temperature room temperature.

[0066] Sample analysis

[0067] The XRD pattern of the room temperature high humidity ozone decomposition catalyst prepared in Example 1 is shown in Figure 1 , Figure 2 The SEM pattern of the room temperature high humidity ozone decomposition catalyst prepared in Example 1 is shown in ,

[0068] The Mn element and Co / Ce / Ni / Cu molar ratio of the catalyst prepared in Examples 1-4 is (4.5-5.5):1.

[0069] The catalyst prepared in Examples 1-5 is placed in a fixed bed reactor for activity evaluation, the total gas flow is 1L / min, 1.5ppm O3, dry / 4vol% H2O, catalyst dosage 0.04g, reaction space velocity 1500L / (g·h) -1 , testing temperature room temperature. The ozone decomposition performance of Examples 1-5 is tested under 15h dry and 4vol% H2O condition respectively, as shown in Figure 3 and 4 , the sample of Example 1 has the highest ozone decomposition rate under both conditions, and the decomposition rate is close to 100%. The ozone decomposition capacity of Example 1 can also be proved by the result chart of ozone detection test paper Figure 5 . The stability and continuous water resistance test of the sample of Example 1 shows that Figure 6 , after 100h operation respectively, the ozone decomposition rate can still be maintained close to 100%. It proves that Example 1 has excellent stability and water resistance, and is not easy to be denatured and deactivated, which can also be further verified by the XRD and SEM data 4.5 of the sample before and after reaction (MnCo2O 4.5 -F and MnCo2O -U) Figures 7-8 .

[0070] The BET test results of the ozone decomposition catalyst prepared in Examples 1-5 are shown in Table 1.

[0071]

Claims

1. A method for preparing a catalyst for ozone decomposition, characterized in that, Includes the following steps: (1) Cobalt nitrate and chelating agent are ground in a mortar, and then a nitrate precursor of Mn element is added to form a rheological phase and grinding is continued; the chelating agent is oxalic acid dihydrate; the nitrate precursor of Mn element is manganese nitrate solution; (2) During the grinding process, as the liquid moisture decreases, a small amount of solvent is added and the mixture is ground thoroughly to obtain a rheological phase mixed metal solution; (3) The rheological phase mixed metal solution obtained by grinding is transferred to a reaction vessel, heated and activated in an oven, and then subjected to solid-liquid separation, washing, drying and calcination in sequence to obtain the catalyst; the catalyst is a bimetallic oxide with a three-dimensional square structure, wherein the bimetals are cobalt and manganese; and the specific bimetallic structure of the catalyst is MnCo2O 4.5 The catalyst has a specific surface area of ​​63.33~113.35 m². 2 / g; The conditions for heating and activation of the rheological phase mixed metal solution are: heating at 100-110℃ for 7-9 h; the conditions for calcination are: calcination at 450-550℃ for 5-7 h.

2. The method for preparing the catalyst for ozone decomposition according to claim 1, characterized in that, In step (1), the molar ratio of cobalt nitrate to chelating agent oxalic acid dihydrate is (0.8-1.2):

1.

3. The method for preparing the catalyst for ozone decomposition according to claim 1, characterized in that, In step (2), the solvent is deionized water.

4. The method for preparing the catalyst for ozone decomposition according to claim 1, characterized in that, In step (3), the molar ratio of cobalt to manganese in the rheological phase mixed metal solution is 1:(4.5-5.5).

5. The method for preparing the catalyst for ozone decomposition according to claim 1, characterized in that, In step (3), the drying conditions are: drying at 100-110℃ for 11-13 h.

6. The catalyst prepared by the method of claim 1 is used for the catalytic decomposition of ozone, characterized in that, It is applicable to various low-concentration ozone pollution sources and ultraviolet photolysis terminal ozone decomposition; the ozone pollution sources include air purifiers, sterilization cabinets, and printers.

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