CN114054020B - Perovskite structure material and application thereof in formaldehyde removal at room temperature - Google Patents

Abstract

The invention discloses a perovskite structure material and application thereof in preparing a moisture-resistant catalyst for removing formaldehyde at room temperature. The perovskite structure material has the following chemical general formula: MMnO ₃ Wherein the M metal is one or two of copper, zinc, iron and nickel. The perovskite structure material can be used as a moisture-resistant catalyst for removing formaldehyde at room temperature, and compared with a noble metal catalyst, the moisture-resistant perovskite crystal catalyst for removing formaldehyde has low cost and simple preparation method; the use condition is simple, and the operation and implementation are convenient; can be used for effectively removing formaldehyde pollution at room temperature, and can rapidly and stably completely oxidize formaldehyde into CO at room temperature and ambient humidity ₂ And H ₂ O, does not produce secondary pollution; the formaldehyde is removed at room temperature, and the moisture resistance and the stability are excellent. The moisture-resistant catalyst for removing formaldehyde at room temperature is suitable for removing closed and semi-closed formaldehyde pollution in houses, vehicles, offices and the like with environmental humidity.

Description

A perovskite structure material and its application in removing formaldehyde at room temperature

Technical Field

The invention belongs to the field of environmental catalysis, and in particular relates to a perovskite structure material and an application thereof in removing formaldehyde at room temperature.

Background Art

Formaldehyde is a pungent gas released by furniture, textiles, and decoration materials. It is one of the main pollutants in local spaces. The World Health Organization's International Agency for Research on Cancer lists formaldehyde as a Class I carcinogen. Long-term exposure to low concentrations of formaldehyde can cause health problems.

Existing technologies for removing formaldehyde include adsorption, plasma technology, photocatalysis and thermal catalysis, but they have disadvantages such as adsorbent saturation, by-product generation, low efficiency and energy requirements. Room temperature catalytic oxidation technology is an effective method for removing formaldehyde by catalytically oxidizing formaldehyde into carbon dioxide and water at room temperature.

According to literature reports, catalysts that can effectively remove formaldehyde at room temperature mainly include supported precious metal Pt catalysts (Applied Surface Science, 2017, 411, 105-112; Angewandte Chemie. International Ed. in English, 2021, 60 (12): 6377-6381), Au catalysts (Environmental Science & Technology, 2014, 48 (16): 9702-9708; Applied Catalysis B: Environmental, 2020, 268: 118461-118466) and Ag catalysts (Catalysis Today, 2016, 277, 257-265), etc. CN 102240549 A discloses a catalytic technology for removing formaldehyde at room temperature with high efficiency and moisture resistance, using honeycomb ceramics as a carrier, first loading pore-doped Ag-doped MnO ₂ , and then loading precious metal Pt as an active component. However, the limited total amount and high price of precious metals severely restrict the practical application of precious metal catalysts.

Transition metals have been widely studied because of their low cost, but the water vapor in the air affects the activity and stability of the catalyst. As the humidity increases, the conversion rate of formaldehyde decreases. For example, the conversion rate of formaldehyde on the spinel MnCo ₂ O ₄ catalyst decreases with increasing humidity at room temperature and is completely deactivated within 2 hours (Applied Catalysis B: Environmental, 2019, 254, 76-85.). At 99°C on ε-MnO ₂ , the addition of water (relative humidity of 46%) reduces the conversion rate of formaldehyde from about 60% to 49% (Chemical Engineering Journal 2020, 388.124146-124157). At room temperature, the addition of water (relative humidity of 38%) on the _MnO2 catalyst reduced the initial formaldehyde conversion rate from 45% to 12%, and it was completely deactivated in 50 minutes (Journal of Hazardous Materials, 2021, 414, 125542-125552). The phenomenon of decreased formaldehyde conversion rate with increasing humidity was also observed on the MnOx _{- CeO2} mixed oxide catalyst (Applied Catalysis B: Environmental 2006, 62 (3-4), 265-273.). However, it took 11 hours for the _MnO2 catalyst to completely convert 200 ppm formaldehyde into _CO2 and _H2O (Environmental Science & Technology, 2015, 49 (20): 12372-12379).

Therefore, achieving rapid and stable conversion of formaldehyde to _CO2 and _H2O at room temperature in the presence of ambient humidity remains a challenge.

Summary of the invention

The purpose of the present invention is to provide a perovskite structure material and its application in removing formaldehyde at room temperature. The perovskite structure material is a _MMnO3 catalyst with a perovskite structure, and the M metal is one or two of copper, zinc, iron, and nickel. The formaldehyde can be quickly and stably completely oxidized into _CO2 and _H2O under ambient humidity. The applicable humidity range is wide, and the preparation method is simple. The cost is lower than that of precious metal catalysts. No external energy input is required during the catalytic reaction. The perovskite structure material is suitable for removing formaldehyde pollution in closed and semi-closed places such as homes, cars, and offices where ambient humidity exists.

In a first aspect, the present invention provides a perovskite structure material having the following general chemical formula: MMnO ₃ , wherein the metal M is one or a combination of two of copper, zinc, iron, and nickel. The combination exemplarily includes a combination of copper and zinc, a combination of copper and iron, a combination of copper and nickel, a combination of zinc and iron, a combination of zinc and nickel, a combination of iron and nickel, and the like.

In the above-mentioned perovskite structural material, the M metal may be a combination of copper and zinc. Preferably, the molar ratio of copper to zinc is x:(1-x), x=0.01-0.99, for example, 0.01:0.99, 0.10:0.90, 0.30:0.70, 0.45:0.55, 0.50:0.50, 0.65:0.35, 0.80:0.20, etc.

In the above-mentioned perovskite structural material, the M metal may be a combination of copper and iron. Preferably, the molar ratio of copper to iron is x:(1-x), x=0.02~0.98, for example, 0.02:0.98, 0.20:0.80, 0.30:0.70, 0.45:0.55, 0.50:0.50, 0.70:0.30, 0.85:0.15, etc.

In the above-mentioned perovskite structural material, the M metal is a combination of copper and nickel. Preferably, the molar ratio of copper to nickel is x:(1-x), x=0.1~0.9, for example 0.10:0.90, 0.20:0.80, 0.30:0.70, 0.50:0.50, 0.80:0.20, 0.90:0.10, etc.

In the above-mentioned perovskite structural material, the M metal is a combination of zinc and iron. Preferably, the molar ratio of zinc to iron is x:(1-x), x=0.05~0.95, for example, 0.05:0.95, 0.10:0.90, 0.35:0.65, 0.45:0.55, 0.50:0.50, 0.80:0.20, 0.95:0.05, etc.

In the above-mentioned perovskite structural material, the M metal is a combination of zinc and nickel. Preferably, the molar ratio of zinc to nickel is x:(1-x), x=0.2~0.8, for example 0.20:0.80, 0.30:0.70, 0.45:0.55, 0.50:0.50, 0.6:0.4, 0.80:0.20, etc.

In the above-mentioned perovskite structural material, the M metal is a combination of iron and nickel. Preferably, the molar ratio of iron to nickel is x:(1-x), x=0.15~0.85, for example, 0.15:0.85, 0.20:0.80, 0.30:0.70, 0.45:0.55, 0.50:0.50, 0.80:0.20, 0.85:0.15, etc.

The method for preparing the perovskite structure material comprises the following steps:

(1) mixing an aqueous solution of a manganese salt with an aqueous solution of a metal salt of the M metal to obtain a metal salt solution;

(2) mixing the aqueous solution of bicarbonate with the metal salt solution for co-precipitation to obtain a precipitate;

(3) Drying the precipitate and then calcining it to obtain the perovskite structure material.

In step (1), the manganese salt may be any water-soluble manganese salt, such as manganese nitrate;

The metal salt of the M metal may be any water-soluble metal salt of the M metal, such as nitrate M salt;

The ratio of the aqueous solution of the manganese salt to the aqueous solution of the metal salt of the M metal is controlled so that the molar ratio of manganese to M metal is 1:5 to 5:1, specifically 1:1;

For example, the concentration of the aqueous solution of the manganese salt may be 0.1 mmol/L to 200 mmol/L, specifically 50 mmol/L;

The concentration of the aqueous solution of the metal salt of the M metal may be 0.1 mmol/L to 200 mmol/L, specifically 50 mmol/L;

The volume ratio of the aqueous solution of the manganese salt to the aqueous solution of the metal salt of the M metal may be 1:9 to 9:1, specifically 1:1.

In step (2), the concentration of the bicarbonate may be 0.1 mmol/L to 500 mmol/L, specifically 36 mmol/L;

The bicarbonate may be any one of NH ₄ HCO ₃ , KHCO ₃ , and NaHCO ₃ ;

The volume ratio of the aqueous solution of bicarbonate to the metal salt solution may be 1:9 to 9:1, specifically 1:1.

In step (2), the coprecipitation temperature may be room temperature (15-30° C.) and the coprecipitation time may be 12 hours;

The coprecipitation is carried out under stirring conditions;

The method further comprises a step of washing the precipitate after the coprecipitation, such as washing the precipitate with ultrapure water and anhydrous ethanol for multiple times.

In step (3), the drying temperature may be 60° C. to 100° C., specifically 60° C.; the drying time may be 1 to 12 hours, specifically 6 hours;

The calcination is carried out in air;

The calcination temperature may be 120-550°C, specifically 350°C;

The calcination time may be 1 to 10 hours, specifically 4 hours.

In a second aspect, the present invention provides the use of the above-mentioned perovskite structure material in removing formaldehyde at room temperature in the presence of ambient humidity or in preparing a moisture-resistant catalyst for removing formaldehyde at room temperature.

The M metal and the Mn metal in the perovskite structure material are connected by oxygen atoms to produce a synergistic effect, so that the catalyst has H ₂ O affinity.

The humidity in the formaldehyde removal environment may be 0% to 90%, preferably 40% to 65%.

The concentration of formaldehyde in the formaldehyde removal environment may be 2 to 200 ppm.

In a third aspect, the present invention provides a moisture-resistant catalyst for removing formaldehyde at room temperature, which is made of the above-mentioned perovskite structure material.

The catalyst of the present invention can be prepared and molded into different structures according to actual uses. For example, it can be made into a honeycomb shape for use in an air purification device, and can be prepared into particles for placement in a closed space.

In a fourth aspect, the present invention provides a method for removing formaldehyde, comprising the following steps: using any of the above-mentioned moisture-resistant catalysts to remove formaldehyde at room temperature.

The moisture-resistant catalyst can remove formaldehyde at room temperature and ambient humidity, completely oxidizing formaldehyde into carbon dioxide and water.

The humidity of the formaldehyde removal environment of the moisture-resistant catalyst is 0% to 90%, preferably 40% to 65%.

The concentration of formaldehyde in the formaldehyde removal environment of the moisture-resistant catalyst is 2 to 200 ppm.

In a fifth aspect, the present invention provides a formaldehyde removal device, comprising a catalyst assembly, wherein the catalyst in the catalyst assembly is the moisture-resistant catalyst described in any one of the above items.

The assembly process of the formaldehyde removal device is as follows: first, a powdered catalyst is molded into a catalyst unit, then the catalyst unit is assembled to form a catalyst assembly for removing formaldehyde, and then it is placed in an air purification device.

When in use, flowing air passes through the above device, and formaldehyde contained in the air contacts the catalyst component in the device and is oxidized and decomposed into carbon dioxide and water by the catalyst, thereby achieving the removal of formaldehyde.

Compared with the prior art, the advantages of the present invention are:

(1) Compared with precious metal catalysts, the moisture-resistant perovskite crystal catalyst for removing formaldehyde of the present invention has low cost and simple preparation method.

(2) The catalyst for formaldehyde removal of the present invention has simple use conditions and is easy to operate and implement. It can be used to effectively remove formaldehyde pollution at room temperature. The catalyst can quickly and stably oxidize formaldehyde to _CO2 and _H2O completely at room temperature and humidity without generating secondary pollution. The _CO2 selectivity reaches 100%, and the formaldehyde conversion rate can reach 100%.

(3) The catalyst of the present invention removes formaldehyde at room temperature and has excellent moisture resistance and stability. Under conditions of relative humidity of 40% and 65%, the formaldehyde conversion rate can reach 100%, and the _CO2 selectivity also reaches 100%. Even under high humidity conditions of 90% relative humidity, the formaldehyde conversion rate can be greater than 90%, the _CO2 selectivity reaches 100%, and the formaldehyde conversion rate of the catalyst remains at 90% within 1000 hours.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an XRD pattern of ZnMnO ₃ prepared in Example 1 of the present invention.

DETAILED DESCRIPTION

The present invention is further described in detail below in conjunction with specific embodiments, and the examples provided are only for illustrating the present invention, rather than for limiting the scope of the present invention. The examples provided below can be used as a guide for further improvements by those of ordinary skill in the art, and do not constitute a limitation of the present invention in any way.

The experimental methods in the following examples, unless otherwise specified, are all conventional methods, and are performed according to the techniques or conditions described in the literature in the field or according to the product instructions. The materials, reagents, etc. used in the following examples, unless otherwise specified, can all be obtained from commercial channels.

Example 1: Preparation of a moisture-resistant catalyst for removing formaldehyde at room temperature

The moisture-resistant catalyst for removing formaldehyde at room temperature was prepared as follows:

(1) preparing an ammonium bicarbonate solution with a concentration of 36 mmol/L; mixing a manganese nitrate solution with a concentration of 50 mmol/L and a zinc nitrate solution with a concentration of 50 mmol/L in a volume ratio of 1:1 to obtain a metal mixed solution manganese zinc solution;

(2) quickly adding the prepared precipitant solution ammonium bicarbonate solution to the metal mixed solution manganese zinc solution (the volume ratio of the precipitant solution to the metal mixed solution manganese zinc solution is 1:1), stirring at room temperature (25°C) for 12 hours, and washing the resulting precipitate with ultrapure water and anhydrous ethanol;

(3) The washed precipitate was dried at 60°C for 6 hours and then calcined in air at 350°C for 4 hours. The resulting catalyst was recorded as ZnMnO ₃ .

The XRD result of ZnMnO ₃ is shown in Figure 1, which is a perovskite structure material.

0.2 g of catalyst ZnMnO ₃ was fixed in a quartz fixed bed reactor, and the fixed bed reactor was maintained at a temperature of 25°C. The reaction gas composition was 80 ppm formaldehyde, the oxygen concentration was 20%, nitrogen was the balance gas, and the gas flow rate was 50 mL/min. The relative humidity of the reaction gas was 20%, 40%, 65%, and 90%, respectively. The activity evaluation results are shown in Table 1.

Table 1. Catalytic activity of Example 1

Example 2: Preparation of a moisture-resistant catalyst for removing formaldehyde at room temperature

The moisture-resistant catalyst for removing formaldehyde at room temperature was prepared as follows:

(1) preparing an ammonium bicarbonate solution with a concentration of 36 mmol/L; mixing a manganese nitrate solution with a concentration of 50 mmol/L and a ferric nitrate solution with a concentration of 50 mmol/L in a volume ratio of 1:1 to obtain a metal mixed solution, a manganese iron solution;

(2) quickly adding the prepared precipitant solution ammonium bicarbonate solution to the metal mixed solution manganese iron solution (the volume ratio of the precipitant solution to the metal mixed solution is 1:1), stirring at room temperature (25°C) for 12 hours, and washing the resulting precipitate with ultrapure water and anhydrous ethanol;

(3) The washed electrocatalyst was dried at 60°C for 6 hours and then calcined in air at 350°C for 4 hours. The obtained catalyst was recorded as FeMnO ₃ .

0.2 g of catalyst FeMnO ₃ was fixed in a quartz fixed bed reactor, and the fixed bed reactor was maintained at a temperature of 25°C. The reaction gas composition was 160 ppm formaldehyde, the oxygen concentration was 20%, nitrogen was the balance gas, and the gas flow rate was 50 mL/min. The relative humidity of the reaction gas was 20%, 40%, 65%, and 90%, respectively. The activity evaluation results are shown in Table 2.

Table 2. Catalytic activity of Example 2

Example 3: Preparation of a moisture-resistant catalyst for removing formaldehyde at room temperature

The moisture-resistant catalyst for removing formaldehyde at room temperature was prepared as follows:

(1) preparing an ammonium bicarbonate solution with a concentration of 36 mmol/L; mixing a manganese nitrate solution with a concentration of 50 mmol/L and a nickel nitrate solution with a concentration of 50 mmol/L in a volume ratio of 1:1 to obtain a metal mixed solution of nickel-manganese solution;

(2) quickly adding the prepared precipitant solution ammonium bicarbonate solution to the metal mixed solution manganese nickel solution (the volume ratio of the precipitant solution to the metal mixed solution is 1:1), stirring at room temperature (25°C) for 12 hours, and washing the resulting precipitate with ultrapure water and anhydrous ethanol;

(3) The washed precipitate was dried at 60°C for 6 hours and then calcined in air at 350°C for 4 hours. The obtained catalyst was recorded as NiMnO ₃ .

0.2 g of catalyst NiMnO ₃ was fixed in a quartz fixed bed reactor, and the fixed bed reactor was maintained at a temperature of 25°C. The reaction gas composition was 200 ppm formaldehyde, the oxygen concentration was 20%, nitrogen was the balance gas, and the gas flow rate was 50 mL/min. The relative humidity of the reaction gas was 20%, 40%, 65%, and 90%, respectively. The activity evaluation results are shown in Table 3.

Table 3, Catalytic activity of Example 3

Example 4

The rest is the same as in Example 1, except that the amount of catalyst used is 0.1 g and the initial formaldehyde concentration is 20 ppm. The activity evaluation results are shown in Table 4.

Table 4, Catalytic activity of Example 4

Example 5

The rest is the same as Example 2, except that the amount of catalyst used is 0.1 g and the initial formaldehyde concentration is 8 ppm. The activity evaluation results are shown in Table 5.

Table 5. Catalytic activity of Example 5

Example 6

The rest is the same as in Example 3, except that the amount of catalyst used is 0.1 g and the initial formaldehyde concentration is 20 ppm. The activity evaluation results are shown in Table 6.

Table 6, Catalytic activity of Example 6

Example 7: Preparation of a moisture-resistant catalyst for removing formaldehyde at room temperature

The moisture-resistant catalyst for removing formaldehyde at room temperature was prepared as follows:

(1) preparing a 36 mmol/L ammonium bicarbonate solution; mixing a 50 mmol/L manganese nitrate solution, a 25 mmol/L iron nitrate solution, and a 25 mmol/L nickel nitrate solution in a volume ratio of 1:1:1 to obtain a metal mixed solution of manganese, nickel, and iron;

(2) quickly adding the prepared precipitant solution ammonium bicarbonate solution to the metal mixed solution manganese nickel iron solution (the volume ratio of the precipitant solution to the metal mixed solution is 1:1), stirring at room temperature (25°C) for 12 hours, and washing with ultrapure water and anhydrous ethanol;

(3) The washed precipitate was dried at 60°C for 6 hours and then calcined in air at 350°C for 4 hours. The obtained catalyst was recorded as Fe _x Ni _1-x MnO ₃ (x=0.5 in this example).

0.2 g of catalyst Fe _x Ni _1-x MnO ₃ was fixed in a quartz fixed bed reactor, and the fixed bed reactor was maintained at a temperature of 25°C. The reaction gas composition was 2 ppm formaldehyde, the oxygen concentration was 20%, nitrogen was the balance gas, and the gas flow rate was 50 mL/min. The relative humidity of the reaction gas was 20%, 40%, 65%, and 90%, respectively. The activity evaluation results are shown in Table 7.

Table 7, Catalytic activity of Example 7

Example 8

The rest is the same as Example 7, but the initial formaldehyde concentration is 180 ppm. The activity evaluation results are shown in Table 8.

Table 8, Catalytic activity of Example 8

Example 9: Preparation of a moisture-resistant catalyst for removing formaldehyde at room temperature

The moisture-resistant catalyst for removing formaldehyde at room temperature was prepared as follows:

(1) preparing an ammonium bicarbonate solution with a concentration of 36 mmol/L; mixing a manganese nitrate solution with a concentration of 50 mmol/L, a zinc nitrate solution with a concentration of 25 mmol/L, and a ferric nitrate solution with a concentration of 25 mmol/L in a volume ratio of 1:1:1 to obtain a metal mixed solution of manganese, zinc, and iron;

(2) quickly adding the prepared precipitant solution ammonium bicarbonate solution to the metal mixed solution manganese, zinc and iron solution (the volume ratio of the precipitant solution to the metal mixed solution is 1:1), stirring at room temperature (25°C) for 12 hours, and washing with ultrapure water and anhydrous ethanol;

(3) The washed precipitate was dried at 60°C for 6 hours and then calcined in air at 350°C for 4 hours. The obtained catalyst was recorded as _{ZnxFe1 -xMnO3 (} x=0.5 in this example).

0.2 g of catalyst Zn _x Fe _1-x MnO ₃ was fixed in a quartz fixed bed reactor, and the fixed bed reactor was maintained at a temperature of 25°C. The reaction gas composition was 60 ppm formaldehyde, the oxygen concentration was 20%, nitrogen was the balance gas, and the gas flow rate was 50 mL/min. The relative humidity of the reaction gas was 20%, 40%, 65%, and 90%, respectively. The activity evaluation results are shown in Table 9.

Table 9, Catalytic activity of Example 9

Example 10

The rest is the same as Example 9, but the initial concentration of formaldehyde is 200 ppm. The activity evaluation results are shown in Table 10.

Table 10, Catalytic Activity of Example 10

Example 11: Preparation of a moisture-resistant catalyst for removing formaldehyde at room temperature

The moisture-resistant catalyst for removing formaldehyde at room temperature was prepared as follows:

(1) preparing an ammonium bicarbonate solution with a concentration of 36 mmol/L; mixing a manganese nitrate solution with a concentration of 50 mmol/L, a zinc nitrate solution with a concentration of 25 mmol/L, and a nickel nitrate solution with a concentration of 25 mmol/L in a volume ratio of 1:1:1 to obtain a metal mixed solution of manganese, zinc, and nickel;

(2) quickly adding the prepared precipitant solution ammonium bicarbonate solution to the metal mixed solution manganese zinc nickel solution (the volume ratio of the precipitant solution to the metal mixed solution is 1:1), stirring at room temperature (25°C) for 12 hours, and washing with ultrapure water and anhydrous ethanol;

(3) The washed precipitate was dried at 60°C for 6 hours and then calcined in air at 350°C for 4 hours. The obtained catalyst was recorded as _{ZnxNi1 -xMnO3 (} x=0.5 in this example).

0.2 g of catalyst Zn _x Ni _1-x MnO ₃ was fixed in a quartz fixed bed reactor, and the fixed bed reactor was maintained at a temperature of 25°C. The reaction gas composition was 20 ppm formaldehyde, the oxygen concentration was 20%, nitrogen was the balance gas, and the gas flow rate was 50 mL/min. The relative humidity of the reaction gas was 20%, 40%, 65%, and 90%, respectively. The activity evaluation results are shown in Table 11.

Table 11, Catalytic activity of Example 11

Example 12

The rest is the same as Example 11, but the initial formaldehyde concentration is 200 ppm. The activity evaluation results are shown in Table 12.

Table 12, Catalytic activity of Example 12

Example 13

0.2 g of the catalyst ZnMnO ₃ of Example 1 was placed in a sealed 10 L transparent chamber containing formaldehyde at a reaction temperature of 25°C. Formaldehyde gas was generated by the volatilization of polyoxymethylene with a concentration of 10 ppm. The oxygen concentration in the air was about 20%. The relative humidity of the reaction gas was 20%, 40%, 65%, and 90%, respectively. After 60 minutes of reaction, the formaldehyde concentration detected by the formaldehyde detector dropped to 0 ppm.

Embodiment 14

The rest is the same as Example 13, but the initial formaldehyde concentration is 120 ppm. The activity evaluation results are shown in Table 13.

Table 13, Catalytic activity of Example 14

Embodiment 15

The rest is the same as Example 13, but the initial formaldehyde concentration is 200 ppm. The activity evaluation results are shown in Table 14.

Table 14, Catalytic activity of Example 15

Example 16

0.2 g of the catalyst FeMnO ₃ of Example 2 was placed in a sealed 10 L transparent chamber containing formaldehyde, and the reaction temperature was 25°C. Formaldehyde gas was generated by the volatilization of polyoxymethylene, with a concentration of 80 ppm. The oxygen concentration in the air was about 20%, and the relative humidity of the reaction gas was 20%, 40%, 65%, and 90%, respectively. After 60 minutes of reaction, the formaldehyde concentration was detected by a formaldehyde detector, and the activity evaluation results are shown in Table 15.

Table 15, Catalytic activity of Example 16

Embodiment 17

The rest is the same as Example 16, but the initial formaldehyde concentration is 200 ppm. The activity evaluation results are shown in Table 16.

Table 16, Catalytic Activity of Example 17

Embodiment 18

0.2 g of the catalyst NiMnO ₃ of Example 3 was placed in a sealed 10 L transparent chamber containing formaldehyde, and the reaction temperature was 25°C. Formaldehyde gas was generated by the volatilization of polyoxymethylene, with a concentration of 2 ppm. The oxygen concentration in the air was about 20%, and the relative humidity of the reaction gas was 20%, 40%, 65%, and 90%, respectively. After 60 minutes of reaction, the formaldehyde concentration detected by the formaldehyde detector dropped to 0 ppm.

Embodiment 19

The rest was the same as in Example 18, except that the formaldehyde concentration was 200 ppm. The activity evaluation results are shown in Table 17.

Table 17, Catalytic Activity of Example 19

Embodiment 20

0.1 g of the catalyst Zn _x Ni _1-x MnO ₃ of Example 11 was placed in a sealed 10 L transparent chamber containing formaldehyde at a reaction temperature of 25°C. Formaldehyde gas was generated by the volatilization of polyoxymethylene with a concentration of 2 ppm. The oxygen concentration in the air was about 20%. The relative humidity of the reaction gas was 20%, 40%, 65%, and 90%, respectively. After 60 minutes of reaction, the formaldehyde concentration detected by the formaldehyde detector dropped to 0 ppm.

Embodiment 21

The rest was the same as in Example 20, except that the formaldehyde concentration was 180 ppm. The activity evaluation results are shown in Table 18.

Table 18, Catalytic Activity of Example 21

Example 22

0.1 g of the catalyst Fe _x Ni _1-x MnO ₃ of Example 7 was placed in a sealed 10 L transparent chamber containing formaldehyde, and the reaction temperature was 25°C. Formaldehyde gas was generated by the volatilization of polyoxymethylene, with a concentration of 5 ppm. The oxygen concentration in the air was about 20%, and the relative humidity of the reaction gas was 20%, 40%, 65%, and 90%, respectively. After 60 minutes of reaction, the formaldehyde concentration detected by the formaldehyde detector dropped to 0 ppm.

Embodiment 23

The rest is the same as Example 22, but the initial formaldehyde concentration is 200 ppm. The activity evaluation results are shown in Table 19.

Table 19, Catalytic Activity of Example 23

Embodiment 24,

First, 500 grams of powdered Fe _x Ni _1-x MnO ₃ catalyst were molded into granular catalyst units (cylindrical particles with a particle size of 0.5-1 cm long and 0.1-0.5 in diameter), and then the granular catalyst units were placed in a porous box to make a catalyst assembly for removing formaldehyde, which was then placed in the air exchange port of an air purification device, and finally the air purification device was placed in a 20m ² atmospheric chamber. The atmospheric chamber temperature was 25°C. Formaldehyde gas was generated by the volatilization of polyoxymethylene with a concentration of 2ppm, the oxygen concentration in the air was about 20%, and the relative humidity of the reaction gas was 20%, 40%, 65%, and 90%, respectively. After 60 minutes of reaction, the formaldehyde concentration dropped to 0ppm.

The above embodiments are only specific examples of the present invention, which are used to illustrate the detailed composition and use of the catalyst in the present invention, but do not mean that the present invention can only be implemented by relying on the above detailed composition and use. Therefore, the protection scope of the present invention is not limited to the above embodiments, and any replacement or optimization ratio of the catalyst raw materials in the present invention, addition of other auxiliary components, optimization or replacement of application parameters, etc., are all within the protection scope of the present invention.

Claims (2)

1. Application of perovskite structure material in removing formaldehyde under room temperature;

the perovskite structure material has the following chemical general formula: MMnO ₃ Wherein, M metal is one or two of copper, zinc, iron and nickel;

the preparation method of the perovskite structure material comprises the following steps:

(1) Mixing an aqueous solution of manganese salt with an aqueous solution of metal salt of the M metal to obtain a metal salt solution;

(2) Mixing an aqueous solution of bicarbonate with the metal salt solution for coprecipitation to obtain a precipitate;

(3) Drying the precipitate and roasting to obtain the perovskite structure material;

the ratio of the aqueous solution of the manganese salt to the aqueous solution of the metal salt of the M metal is controlled to be 1:1, a step of;

the concentration of the aqueous solution of bicarbonate is 36mmol/L;

the volume ratio of the aqueous bicarbonate solution to the metal salt solution is 1:9~9:1, a step of;

the temperature of the coprecipitation is 15-30 ℃ and the time is 12 hours;

the roasting is carried out in air;

the roasting temperature is 350 ℃ and the roasting time is 4 hours;

the humidity of the formaldehyde removal environment is 40% -65%;

the concentration of formaldehyde in the formaldehyde removing environment is 2-200 ppm.

2. The use according to claim 1, characterized in that: the M metal is a combination of copper and zinc, and the molar ratio of the copper to the zinc is x (1-x), wherein x=0.01-0.99; or alternatively, the first and second heat exchangers may be,

the M metal is a combination of copper and iron, and the molar ratio of the copper to the iron is x (1-x), wherein x=0.02-0.98; or alternatively, the first and second heat exchangers may be,

the M metal is a combination of copper and nickel, and the molar ratio of the copper to the nickel is x (1-x), wherein x=0.1-0.9; or alternatively, the first and second heat exchangers may be,

the M metal is a combination of zinc and iron, and the molar ratio of the zinc to the iron is x (1-x), wherein x=0.05-0.95; or alternatively, the first and second heat exchangers may be,

the M metal is a combination of zinc and nickel, and the molar ratio of the zinc to the nickel is x (1-x), wherein x=0.2-0.8; or alternatively, the first and second heat exchangers may be,

the M metal is a combination of iron and nickel, the molar ratio of iron to nickel is x (1-x), and x=0.15-0.85.

Images