阅读说明：本技术 一种分解臭氧的银锰催化剂、其制备方法及用途 (Silver-manganese catalyst for decomposing ozone, preparation method and application thereof ) 是由 贺泓 马金珠 李晓彤 张长斌 于 2019-10-24 设计创作，主要内容包括：本发明公开了一种分解臭氧的银锰催化剂,所述银锰催化剂包括α-Mn<Sub>2</Sub>O<Sub>3</Sub>以及负载在其上的Ag单质,所述α-Mn<Sub>2</Sub>O<Sub>3</Sub>作为载体和第一活性组分,所述Ag单质作为第二活性组分,以所述银锰催化剂的总质量为100％计,所述Ag单质的质量百分含量大于1％,所述Ag单质和α-Mn<Sub>2</Sub>O<Sub>3</Sub>之间存在相互作用。本发明提供的银锰催化剂可应用于宽温度的条件下,长时间高效分解臭氧,其经72h的劣化条件下催化臭氧,依然可以保持80％以上的转化率。可应用于各种含有臭氧的气体的处理,有望用于建筑物外表面或机动车散热器等来解决大气中的臭氧污染问题,并可应用于高空飞行器解决臭氧污染问题。(The invention discloses a silver-manganese catalyst for decomposing ozone, which comprises alpha-Mn 2 O 3 And Ag simple substance loaded on the alpha-Mn-alpha 2 O 3 The Ag is used as a carrier and a first active component, the simple substance is used as a second active component, the total mass of the silver-manganese catalyst is 100%, the mass percentage content of the simple substance is more than 1%, and the simple substance and alpha-Mn are 2 O 3 There is an interaction between them. The silver-manganese catalyst provided by the invention can be applied to the condition of wide temperature, can efficiently decompose ozone for a long time, and can still maintain the conversion rate of over 80% after catalyzing ozone under the degradation condition of 72 h. Can be used for treating various gases containing ozone, and is expected to be used on the outer surface of buildings or motor vehicle radiators and the like to solve the atmosphereThe ozone pollution problem in the process can be solved, and the ozone pollution problem can be solved by applying the high-altitude aircraft.)

1. A silver manganese catalyst for decomposing ozone, characterized in that the silver manganese catalyst comprises alpha-Mn₂O₃And Ag simple substance loaded on the alpha-Mn-alpha₂O₃As a carrier and a first active component, the Ag is used as a second active component;

and the mass percentage of the Ag simple substance is more than 1 percent based on the total mass of the silver-manganese catalyst being 100 percent.

2. The silver-manganese catalyst according to claim 1, wherein the mass percentage of the Ag element is 2-12%, preferably 4-10%, based on 100% of the total mass of the silver-manganese catalyst.

3. Silver manganese catalyst according to claim 1 or 2, characterized in that the α -Mn is₂O₃The particle size of the Ag is 40-150 nm, and the particle size of the Ag simple substance is 2-26 nm.

4. A method of preparing a silver manganese catalyst according to any one of claims 1 to 3, characterized in that it comprises the following steps:

mixing alpha-Mn₂O₃Dissolving the carrier in water, adding AgNO₃Stirring, rotary evaporation at 40-70 ℃, drying and roasting to obtain the silver-manganese catalyst.

5. Method according to claim 4, characterized in that AgNO is added₃The solution is stirred evenly before;

preferably, the stirring is carried out for 2-24h at the temperature of 10-40 ℃;

preferably, the reaction is carried out under the condition of rotary evaporation for 2-5 hours;

preferably, the drying temperature is 90-150 ℃, and the drying time is 12-24 h;

preferably, the roasting temperature is 500-900 ℃, and the roasting time is 2-5 h.

6. The method of claim 4 or 5, wherein the α -Mn is₂O₃The specific surface area of the carrier is more than or equal to 20m²(iv) g, particle size is in the range of 40-150 nm.

7. The method of any one of claims 4-6, wherein the α -Mn is₂O₃The carrier is prepared by the following method:

(a) dissolving soluble manganese salt in water, dropwise adding a sodium carbonate solution into the obtained manganese salt solution until the pH value is between 8 and 9, precipitating manganese ions, and keeping stirring in the whole dropwise adding process to obtain a manganese carbonate precipitate;

(b) drying and roasting to obtain alpha-Mn₂O₃And (3) a carrier.

8. The process according to claim 7, wherein the soluble manganese salt of step (a) is manganese sulfate and/or manganese nitrate;

preferably, the concentration of the manganese salt solution in the step (a) is 0.1-1 mol/L;

preferably, the concentration of the sodium carbonate solution in the step (a) is 0.2-2 mol/L;

preferably, the stirring of step (a) is uniform stirring;

preferably, the manganese carbonate precipitate obtained in step (a) is washed to neutrality.

9. The method according to claim 7 or 8, wherein the drying temperature in step (b) is 90-150 ℃ and the drying time is 12-24 h;

preferably, the roasting temperature in the step (b) is 500-900 ℃, and the roasting time is 2-5 h.

10. Use of the silver manganese catalyst according to any one of claims 1 to 3 for decomposing ozone.

Technical Field

The invention belongs to the technical field of catalysts, and relates to a silver-manganese catalyst for decomposing ozone, and a preparation method and application thereof.

Background

Ozone is a trace gas in the earth atmosphere, which is formed by decomposing oxygen molecules in the atmosphere into oxygen atoms by solar radiation, and then combining the oxygen atoms with surrounding oxygen molecules, and contains 3 oxygen atoms. More than 90% of ozone in the atmosphere exists in the upper part or stratosphere of the atmosphere, 10-50 kilometers away from the ground, and the atmospheric ozone layer can resist harmful ultraviolet rays from directly irradiating the earth. And a small part of ozone molecules wander to the ground and still have a certain effect on blocking ultraviolet rays. However, excessive increases in ozone concentration in the atmosphere near the ground can cause a number of problems, such as harmful effects on human health, ozone which can cause eye burning and dryness, and the like, also can affect respiratory tract and lung functions, increasing the risk of respiratory diseases, and higher ozone concentrations can also be harmful to plants.

In industrially developed countries, the source of ozone in urban air is mainly the products of automobile exhaust gas generated by photochemical catalytic reaction. Ozone in indoor air is mainly derived from the atmospheric environment. The normal atmosphere contains a very small amount of ozone, and the concentration of the ozone is about 0.02-0.06 mg/m³Average of 0.03mg/m³. The concentration of the generated ozone can exceed several times or even tens times of the atmospheric background value while the sulfur dioxide and the nitrogen oxide polluting the city generate photochemical smog.

At present, methods for ozone treatment mainly include a heat treatment method, an activated carbon adsorption method, a dilution method, an electromagnetic wave radiation decomposition method, a chemical liquid absorption method, and a catalytic decomposition method, and among them, the catalytic decomposition method is the most ideal method for decomposing ozone so far, and has advantages of high efficiency, safety, stability, economy, and the like, and is a focus of research.

CN108212153A discloses a self-supporting noble metal modified manganese-based composite oxide catalyst, a preparation method and an application thereof, wherein the self-supporting noble metal modified manganese-based composite oxide catalyst is formed by firstly growing Al in situ on an aluminum substrate₂O₃The nano-sheets form a catalyst carrier, and the catalyst carrier is sequentially loaded with manganese-based composite oxides and active noble metals to obtain the catalyst; the manganese-based composite oxidationThe catalyst consists of manganese oxide and assistant metal oxide, wherein in the catalyst, the manganese-based composite oxide accounts for 1-10% by mass, the active noble metal accounts for 0.001-0.1% by mass, and the balance is a catalyst carrier. Experiments show that the catalyst has the characteristics of good thermal conductivity, high permeability and stable structure, has ordered structure and shape-setting characteristics, and can fully meet the catalytic performance requirements of catalytic decomposition reaction of ozone and selective catalytic reduction denitration reaction of ammonia. However, the catalyst is complicated in preparation process and is not suitable for mass production in industrial applications.

CN 109908934A discloses a catalyst for ozone catalytic oxidation reaction, which comprises a composite carrier and an active metal component, wherein one or more of noble metals of Pt, Pd, Rh and Ru are used as the active metal component, the composite carrier comprises active carbon and basic carbonate, the basic carbonate is distributed on the outer surface of the active carbon, and the active carbon accounts for 35-90% of the total weight of the composite carrier; the basic carbonate accounts for 10-65% of the total weight of the composite carrier; the basic carbonate is basic magnesium carbonate or a mixture of the basic calcium carbonate and the basic magnesium carbonate. The catalyst has good stability, not only has high COD removal capability, but also can relieve the problem of metal loss. However, the noble metal used in the catalyst is expensive, which is not suitable for practical use.

Therefore, it is necessary to develop a novel catalyst which can efficiently decompose ozone for a long time under a wide temperature range, thereby widening the application range.

Disclosure of Invention

In view of the above problems in the prior art, the present invention aims to provide a silver-manganese catalyst for decomposing ozone, a preparation method and applications thereof.

In order to achieve the purpose, the invention adopts the following technical scheme:

in a first aspect, the present invention provides a silver manganese catalyst for decomposing ozone, the silver manganese catalyst comprising alpha-Mn₂O₃And Ag simple substance loaded on the alpha-Mn-alpha₂O₃As a carrier and a first active component, the Ag is used as the first elementTwo active components, wherein the total mass of the silver-manganese catalyst is 100%, the mass percentage content of the Ag simple substance is more than 1%, and the Ag simple substance and alpha-Mn are₂O₃There is an interaction between them, which is not van der Waals' force, the present invention is illustrated by H in FIG. 3₂The TPR test confirms the presence of this interaction.

In the silver-manganese catalyst of the invention, alpha-Mn₂O₃The interaction existing between the high-stability carrier with the redox performance and the metallic Ag nanoparticles has the capability of improving the ozone decomposition activity, wherein the introduction of the metallic Ag nanoparticles serving as an active component plays a key role in improving the ozone decomposition activity.

Preferably, the mass percentage content of the Ag simple substance (i.e. the loading amount of the Ag simple substance) is 2 to 12%, for example, 2%, 3%, 5%, 5.5%, 6%, 7%, 8%, 9%, 10%, 11%, or 12%, and preferably 4 to 10%, based on 100% of the total mass of the silver-manganese catalyst.

Preferably, the alpha-Mn₂O₃The particle size of (B) is 40-150 nm, such as 40nm, 60nm, 70nm, 80nm, 100nm, 110nm, 120nm, 135nm or 150 nm. The particle size of the Ag simple substance is 2-26 nm, such as 2nm, 4nm, 8nm, 9nm, 10nm, 12nm, 13nm, 15nm, 16nm, 18nm, 20nm, 24nm or 26 nm.

In a second aspect, the present invention provides a method of preparing a silver manganese catalyst as described in the first aspect, the method comprising the steps of:

mixing alpha-Mn₂O₃Dissolving the carrier in water, adding AgNO₃Stirring, rotary evaporation at 40-70 ℃, drying and roasting to obtain the silver-manganese catalyst.

The temperature of rotary evaporation is, for example, 40 deg.C, 45 deg.C, 50 deg.C, 55 deg.C, 58 deg.C, 60 deg.C, 65 deg.C or 70 deg.C, and the reaction is carried out in such a temperature range that silver nitrate is supported on alpha-Mn₂O₃The solvent can be evaporated to dryness as quickly as possible at higher temperature on the carrier, and the boiling point of the solvent needs to be ensured to be lower than that of the solvent because the rotary evaporation process is in a reduced pressure state so as not to cause bumping.

The method of the inventionBy using specific alpha-Mn₂O₃Adding silver nitrate into a carrier, and performing rotary evaporation at 40-70 ℃ in advance to enable the silver nitrate to be loaded on alpha-Mn₂O₃On the carrier, further drying and roasting to convert silver nitrate into silver simple substance, so that alpha-Mn can be obtained₂O₃Bonding is formed between the Ag and the Ag simple substance, the associativity and stability are greatly improved, and the catalytic performance of the Ag-Ag.

In the process of the present invention, alpha-Mn₂O₃The carrier is specially selected, so that the carrier has the advantage of stability under a high-temperature roasting condition, and can ensure that silver nitrate is not oxidized in the roasting process to generate impurity phases such as AgO and the like.

As a preferred technical scheme of the method, AgNO is added₃The solution was previously homogenized.

Preferably, the stirring is performed at 10-40 ℃ for 2-24h, the stirring temperature is 10 ℃, 15 ℃, 20 ℃, 25 ℃, 30 ℃, 35 ℃, 37.5 ℃ or 40 ℃, and the stirring time is 2h, 3.5h, 4h, 6h, 8h, 9h, 10h, 12h, 13h, 15h, 16h, 18h, 20h, 22h or 24 h.

Preferably, the reaction is carried out under rotary evaporation conditions for 2-5h, such as 2h, 2.5h, 3h, 3.5h, 4h or 5 h. During rotary evaporation, a layer of liquid film is formed on the inner surface of the evaporation bottle by the liquid sample due to the action of centripetal force and friction force between the liquid sample and the evaporation bottle, the heating area is large, the solvent can be evaporated to dryness more quickly, and meanwhile, the acting force generated by the rotation of the sample during rotary evaporation can effectively inhibit the boiling of the sample.

Preferably, the drying temperature is 90-150 ℃, such as 90 ℃, 95 ℃, 100 ℃, 110 ℃, 115 ℃, 120 ℃, 130 ℃, 135 ℃, 140 ℃ or 150 ℃, and the drying time is 12-24h, such as 12h, 14h, 15h, 16h, 18h, 20h, 21h, 23h or 24 h. Too low a drying temperature can prolong the drying time and reduce the efficiency; drying temperatures in excess of 200 c may affect the state of Ag, thereby adversely affecting product performance.

Preferably, the temperature of the calcination is 500 to 900 ℃, for example, 500 ℃, 550 ℃, 600 ℃, 650 ℃, 700 ℃, 750 ℃,800 ℃, 850 ℃ or 900 ℃, and the like, wherein the roasting time is 2-5h, such as 2h, 3h, 3.5h, 4h, 4.5h or 5h, and the like. The temperature is lower than 500 ℃, and the impregnated silver nitrate can not be completely decomposed into metallic silver simple substances, so that the product performance is reduced; the temperature is higher than 900 ℃, and the carrier alpha-Mn₂O₃The structure of (2) is easily broken to MnO, and the product performance is also degraded.

As a preferable embodiment of the method of the present invention, the α -Mn is₂O₃The specific surface area of the carrier is more than or equal to 20m²G, e.g. 20m²/g、21m²/g、22m²/g、25m²G or 30m²A grain size of 40-150 nm, such as 40nm, 60nm, 70nm, 80nm, 100nm, 110nm, 120nm, 135nm or 150nm, and has a high degree of crystallization.

Preferably, the alpha-Mn₂O₃The carrier is prepared by the following method:

(a) dissolving soluble manganese salt in water, dropwise adding a sodium carbonate solution into the obtained manganese salt solution until the pH value is between 8 and 9, precipitating manganese ions, and keeping stirring in the whole dropwise adding process to obtain a manganese carbonate precipitate;

(b) drying and roasting to obtain alpha-Mn₂O₃The support, which is itself a catalyst, is catalytically active.

In the method, the pH is, for example, 8, 8.3, 8.5, 9 or the like.

Preferably, the soluble manganese salt of step (a) is manganese sulphate and/or manganese nitrate.

Preferably, the concentration of the manganese salt solution in the step (a) is 0.1-1 mol/L, such as 0.1mol/L, 0.2mol/L, 0.5mol/L, 0.7mol/L or 1 mol/L.

Preferably, the concentration of the sodium carbonate solution of step (a) is 0.2-2mol/L, such as 0.2mol/L, 0.5mol/L, 0.7mol/L, 1.0mol/L, 1.2mol/L, 1.6mol/L or 2mol/L, etc.

Preferably, the stirring of step (a) is uniform stirring.

Preferably, the manganese carbonate precipitate obtained in step (a) is washed to neutrality.

Preferably, the drying in step (b) is carried out at a temperature of 90-150 ℃, such as 90 ℃, 95 ℃, 100 ℃, 110 ℃, 115 ℃, 120 ℃, 130 ℃, 135 ℃, 140 ℃ or 150 ℃ and the like, and the drying time is 12-24h, such as 12h, 14h, 15h, 16h, 18h, 20h, 21h, 23h or 24h and the like.

Preferably, the temperature of the calcination in step (b) is 500-900 ℃, such as 500 ℃, 550 ℃, 600 ℃, 650 ℃, 700 ℃, 750 ℃, 800 ℃, 850 ℃ or 900 ℃ and the like, and the calcination time is 2-5h, such as 2h, 3h, 3.5h, 4h, 4.5h or 5h and the like.

In a third aspect, the present invention provides the use of a silver manganese catalyst as described in the first aspect for decomposing ozone.

Compared with the prior art, the invention has the following beneficial effects:

(1) the silver-manganese catalyst provided by the invention can be applied to efficiently decompose ozone for a long time under the condition of wide temperature, and can still maintain the conversion rate of over 80% after catalyzing ozone under the degradation condition of 12 hours.

(2) The silver-manganese catalyst provided by the invention can be applied to the treatment of various gases containing ozone, is expected to be applied to the outer surface of a building or a radiator of a motor vehicle and the like to solve the problem of ozone pollution in the atmosphere, and can be applied to a high-altitude aircraft to solve the problem of ozone pollution.

Drawings

FIG. 1 is a-Mn₂O₃Support and 6% Ag/α -Mn from example 3₂O₃XRD pattern of the catalyst;

FIG. 2a and FIG. 2b are respectively α -Mn₂O₃SEM and TEM images of the support;

FIGS. 2c and 2d are 6% Ag/α -Mn obtained in example 3₂O₃TEM and HRTEM images of the catalyst.

FIG. 3 is the 6% Ag/α -Mn obtained in example 3₂O₃Catalyst and alpha-Mn₂O₃H of the vector₂TPR contrast plot.

Detailed Description

The technical scheme of the invention is further explained by the specific implementation mode in combination with the attached drawings.

The invention provides a silver-manganese catalyst for decomposing ozone and a preparation method thereof₂O₃The catalyst was used as a support, and then various amounts of Ag were impregnated by impregnation methods, including:

(1) dissolving soluble manganese salt in water, dropwise adding a sodium carbonate solution until the pH value is between 8 and 9, precipitating manganese ions, and keeping stirring in the whole dropwise adding process to obtain a manganese carbonate precipitate;

(2) drying and roasting to obtain alpha-Mn₂O₃A carrier;

(3) mixing alpha-Mn₂O₃Dissolving the carrier in water, adding AgNO₃Stirring, reacting at 40-70 ℃, drying and roasting to obtain the silver-manganese catalyst.

The obtained catalyst consists of alpha-Mn₂O₃And Ag supported on the Ag-Ag alloy consists of simple substance, and the Ag is named as a% Ag/alpha-Mn according to different Ag supporting amounts₂O₃Wherein a is more than or equal to 1 and less than or equal to 12.

The following are typical but non-limiting examples of the invention: