CN114904514B - A kind of ozone decomposition catalyst and its preparation method and application - Google Patents

Abstract

The invention provides an ozonolysis catalyst, a preparation method and application thereof, wherein the preparation method comprises the following steps: (1) Mixing insoluble manganese salt and soluble zirconium salt with a solvent, stirring, and drying to obtain a mixed material; (2) The ozonolysis catalyst is obtained after roasting the mixed material obtained in the step (1), and the manganese oxide is doped with a small amount of zirconium, so that the stability and the catalytic performance of the catalyst can be obviously improved, and the water resistance of the catalyst is improved.

Description

A kind of ozone decomposition catalyst and its preparation method and application

Technical Field

The invention belongs to the technical field of catalysts and relates to an ozone decomposition catalyst and a preparation method and application thereof.

Background technique

More than 90% of the ozone in the atmosphere is in the stratosphere 20 to 30 km above the ground. The stratospheric ozone layer absorbs all solar ultraviolet radiation in the 210 to 290 nm band, thus protecting life on Earth from the effects of strong ultraviolet radiation; the remaining less than 10% of ozone is in the troposphere. It does not come from direct pollution emissions, but is the product of photochemical reactions between volatile organic compounds (VOCs) and nitrogen oxides (NO _x ) under sunlight. It is a typical secondary pollutant and one of the important factors causing regional atmospheric complex pollution in China. When tropospheric ozone, especially near-ground ozone, exceeds natural levels, it will have a significant impact on human health, ecosystems, climate change and other aspects.

At present, the commonly used methods for treating ozone are activated carbon method, thermal decomposition method, liquid absorption method and catalytic decomposition method. Activated carbon is a simple and low-cost method and is often used to remove low-concentration O _3. The process of treating high-concentration O ₃ with activated carbon consumes a lot of heat and is prone to explosion if not handled properly. In addition, activated carbon is easily deactivated and requires frequent regeneration or replacement. Moreover, the removal efficiency is greatly affected by factors such as humidity, airflow, pressure, and concentration, which has great limitations. Removing O ₃ by thermal decomposition requires heating the gas to about 400°C, which has good removal efficiency for high-concentration O _3. However, this method cannot be used for outdoor and indoor O ₃ removal and is only suitable for the treatment of high-concentration industrial waste gas. The reagents used for liquid absorption are mainly sodium thiosulfate or sodium sulfite. The biggest problem with this method is that the waste liquid is difficult to handle. The catalytic decomposition of O ₃ has become a research hotspot due to its mild reaction conditions, high treatment efficiency, environmental friendliness, safety and reliability.

CN111974380A discloses an ozone decomposition catalyst and a preparation method thereof. The preparation method comprises: weighing a nanosol and stirring it; weighing a soluble trivalent cerium salt, adding it to deionized water, stirring and dissolving it, and then slowly dripping it into the nanosol; dripping a carboxyl acid into a mixed slurry, adjusting the mixed slurry to pH=2-4, stirring it for 2-10 hours, and setting it aside; weighing potassium permanganate, adding it to deionized water, stirring and dissolving it, and then slowly dripping it into the mixed slurry, stirring it for 24-48 hours; suction filtering the obtained slurry, and drying the filter cake at 80-120°C to obtain an ozone decomposition catalyst.

CN113559848A discloses a highly active manganese-based catalyst for ozone decomposition and a preparation method thereof. The catalyst is a mixed-valence manganese oxide trimanganese tetraoxide with a spinel structure, which is prepared by the following method: a divalent manganese source, ammonium persulfate, and deionized water are mixed, fully stirred, and maintained at a hydrothermal condition of 70 to 140° C. for 4 to 8 hours, wherein the molar ratio of the divalent manganese source to the ammonium persulfate is 1:(0.5 to 2); then the solid obtained by filtration is dried at 60 to 110° C. for 3 to 12 hours, and finally roasted at 200 to 400° C. under a reducing atmosphere for 4 to 8 hours.

Manganese oxide (MnO _x ) stands out among many metal oxide catalysts due to its high activity (even comparable to that of some precious metals), but it will quickly deactivate under high humidity. Therefore, improving the water resistance of manganese-based catalysts is a difficult point in the study of ozone decomposition catalysts.

Summary of the invention

The purpose of the present invention is to provide an ozone decomposition catalyst and a preparation method and application thereof. The present invention dopes a small amount of zirconium into manganese oxide, which can significantly improve the stability and catalytic performance of the catalyst and improve the water resistance of the catalyst.

In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

In a first aspect, the present invention provides a method for preparing an ozone decomposition catalyst, the preparation method comprising the following steps:

(1) mixing an insoluble manganese salt and a soluble zirconium salt with a solvent, stirring and drying to obtain a mixed material;

(2) The mixed material obtained in step (1) is calcined to obtain the ozone decomposition catalyst.

The present invention adopts an impregnation method to mix an insoluble manganese salt and a soluble zirconium salt in a solvent, and zirconium ions are uniformly attached to the surface of the insoluble manganese salt. After sintering treatment, an ozone decomposition catalyst composed of manganese oxide and zirconium oxide is obtained. The ozone decomposition catalyst has good catalytic effect and good water resistance, and can be used in an environment with high relative humidity.

Preferably, the insoluble manganese salt in step (1) comprises manganese carbonate and/or manganese oxalate.

Preferably, the soluble zirconium salt in step (1) includes any one of zirconium nitrate, zirconium chloride or zirconium sulfate, or a combination of at least two thereof.

Preferably, the molar ratio of the insoluble manganese salt to the soluble zirconium salt in step (1) is 1:(0.01-0.03), for example: 1:0.01, 1:0.015, 1:0.02, 1:0.025 or 1:0.03, etc.

The present invention precisely controls the molar ratio of insoluble manganese salt to soluble zirconium salt, thereby regulating the number and properties of active sites for ozone decomposition, thereby improving the ability of the catalyst to decompose ozone.

Preferably, the stirring time in step (1) is 0.8 to 2 h, for example, 0.8 h, 1 h, 1.2 h, 1.5 h or 2 h.

Preferably, the drying process comprises rotary evaporation.

Preferably, the drying temperature is 50-70°C, for example, 50°C, 55°C, 60°C, 65°C or 70°C.

Preferably, a drying treatment is performed before the roasting treatment in step (2).

Preferably, the temperature of the drying treatment is 90-120°C, for example, 90°C, 100°C, 110°C or 120°C.

Preferably, the drying treatment time is 10 to 20 hours, for example: 10 hours, 12 hours, 15 hours, 18 hours or 20 hours.

Preferably, the temperature of the calcination treatment in step (2) is 350-450°C, for example, 350°C, 380°C, 400°C, 420°C or 450°C.

Preferably, the calcination treatment time is 1.5 to 3 hours, for example, 1.5 hours, 1.8 hours, 2 hours, 2.5 hours or 3 hours.

Preferably, the roasting treatment in step (2) is followed by screening.

Preferably, the mesh number of the sieve for the sieving treatment is 40 to 60 meshes, for example: 40 mesh, 45 mesh, 50 mesh, 55 mesh or 60 mesh, etc.

In a second aspect, the present invention provides an ozone decomposition catalyst, which is prepared by the method described in the first aspect.

The preparation process of the invention is simple, and the product can be obtained only by stirring, drying, roasting, tableting and sieving. The experimental conditions are easy to control, and the experimental process is less affected by human factors.

In a third aspect, the present invention provides a use of the ozone decomposition catalyst as described in the second aspect, wherein the ozone decomposition catalyst is used to catalytically decompose ozone.

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

(1) The present invention dopes a small amount of zirconium into the manganese catalyst, which significantly improves the activity of pure manganese oxide and the stability under high humidity. The preparation method is simple, the raw materials are cheap, and it is suitable for industrial mass production.

(2) The ozone decomposition rate of the catalyst of the present invention can reach more than 51.55% after being tested at 55% humidity for 6 hours. By adjusting the raw material ratio and preparation conditions in the preparation process, the ozone decomposition rate can reach 82.32% after being tested at 55% humidity for 6 hours.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an XRD diagram of the ozone decomposition catalyst described in Example 1.

FIG. 2 is a graph showing the activity comparison of the ozone decomposition catalyst prepared in Example 1 of the present invention and the ozone decomposition catalyst prepared in Comparative Example 1.

Detailed ways

The technical solution of the present invention is further described below by specific implementation methods. It should be understood by those skilled in the art that the embodiments are only used to help understand the present invention and should not be regarded as specific limitations of the present invention.

Example 1

This embodiment provides an ozone decomposition catalyst, which is prepared by the following method:

(1) 0.46 g of zirconium nitrate pentahydrate was fully dissolved in deionized water, and then 6 g of manganese carbonate was slowly added and stirred for 1 h (the molar ratio of zirconium nitrate to manganese carbonate was 0.02:1). The impregnated solution was placed in a rotary evaporator in a 60° C. water bath at a speed of 80 rpm to evaporate the water, and then placed in an oven at 100° C. for 12 h to obtain a mixed material;

(2) The mixed material obtained in step (1) was ground and calcined at 400° C. for 2 h, and passed through a 50-mesh sieve to obtain the ozone decomposition catalyst. The XRD pattern of the ozone decomposition catalyst is shown in FIG. 1 .

Example 2

This embodiment provides an ozone decomposition catalyst, which is prepared by the following method:

(1) 0.35 g of zirconium nitrate pentahydrate was fully dissolved in deionized water, and then 6 g of manganese carbonate was slowly added and stirred for 1 h (the molar ratio of zirconium nitrate to manganese carbonate was 0.015:1). The impregnated solution was placed in a rotary evaporator in a 65° C. water bath at a speed of 85 rpm to evaporate the water, and then placed in an oven at 110° C. for 12 h to obtain a mixed material;

(2) Grinding the mixture obtained in step (1) and calcining it at 420° C. for 1.5 h, and passing it through a 45-mesh sieve to obtain the ozone decomposition catalyst.

Example 3

This embodiment provides an ozone decomposition catalyst, which is prepared by the following method:

(1) 0.2 g of zirconium nitrate pentahydrate was fully dissolved in deionized water, and then 6 g of manganese carbonate was slowly added and stirred for 1 h (the molar ratio of zirconium nitrate to manganese carbonate was 0.005:1). The impregnated solution was placed in a rotary evaporator in a 60° C. water bath at a speed of 80 rpm to evaporate the water, and then placed in an oven at 100° C. for 12 h to obtain a mixed material;

(2) Grinding the mixture obtained in step (1) and calcining it at 400° C. for 2 h, and passing it through a 50-mesh sieve to obtain the ozone decomposition catalyst.

Example 4

This embodiment provides an ozone decomposition catalyst, which is prepared by the following method:

(1) 0.8 g of zirconium nitrate pentahydrate was fully dissolved in deionized water, and then 6 g of manganese carbonate was slowly added and stirred for 1 h (the molar ratio of zirconium nitrate to manganese carbonate was 0.040:1). The impregnated solution was placed in a rotary evaporator in a 60° C. water bath at a speed of 80 rpm to evaporate the water, and then placed in an oven at 100° C. for 12 h to obtain a mixed material;

(2) Grinding the mixture obtained in step (1) and calcining it at 400° C. for 2 h, and passing it through a 50-mesh sieve to obtain the ozone decomposition catalyst.

Example 5

This embodiment provides an ozone decomposition catalyst, which is prepared by the following method:

(1) 0.46 g of zirconium nitrate pentahydrate was fully dissolved in deionized water, and then 6 g of manganese carbonate was slowly added and stirred for 1 h (the molar ratio of zirconium nitrate to manganese carbonate was 0.02:1). The impregnated solution was placed in a rotary evaporator in a 60° C. water bath at a speed of 80 rpm to evaporate the water, and then placed in an oven at 100° C. for 12 h to obtain a mixed material;

(2) Grinding the mixture obtained in step (1), calcining at 300° C. for 2 h, and passing through a 50-mesh sieve to obtain the ozone decomposition catalyst.

Example 6

This embodiment provides an ozone decomposition catalyst, which is prepared by the following method:

(1) 0.46 g of zirconium nitrate pentahydrate was fully dissolved in deionized water, and then 6 g of manganese carbonate was slowly added and stirred for 1 h (the molar ratio of zirconium nitrate to manganese carbonate was 0.02:1). The impregnated solution was placed in a rotary evaporator in a 60° C. water bath at a speed of 80 rpm to evaporate the water, and then placed in an oven at 100° C. for 12 h to obtain a mixed material;

(2) The mixed material obtained in step (1) is ground and calcined at 500° C. for 2 h, and passed through a 50-mesh sieve to obtain the ozone decomposition catalyst.

Comparative Example 1

The only difference between this comparative example and Example 1 is that no zirconium salt is added, and other conditions and parameters are exactly the same as those in Example 1.

Performance Testing:

The ozone decomposition catalysts obtained in Examples 1-6 and Comparative Example 1 were placed in a catalyst activity evaluation device. The activity evaluation was carried out in a fixed bed reactor. The total flow rate of the simulated gas was 1260 ml/min, 20% O ₂ , 20 ppm O ₃ , N ₂ was the balance gas, the catalyst dosage was 0.1 g, the temperature was kept at 25° C., and the reaction space velocity was 756 L/(g·h) ^-1 . The test results are shown in Table 1:

Table 1

As can be seen from Table 1, from Examples 1-6, the ozone decomposition rate of the catalyst of the present invention can reach more than 51.55% after being tested at 55% humidity for 6 hours. By adjusting the raw material ratio and preparation conditions in the preparation process, the ozone decomposition rate can reach 82.32% after being tested at 55% humidity for 6 hours.

By comparing Example 1 with Examples 3-4, it can be seen that in the preparation process of the ozone decomposition catalyst of the present invention, the molar ratio of the insoluble manganese salt to the soluble zirconium salt will affect the catalytic performance of the prepared ozone catalyst. When the molar ratio of the insoluble manganese salt to the soluble zirconium salt is controlled at 1:(0.01-0.03), the catalytic effect of the prepared ozone decomposition catalyst is better. If the amount of zirconium added is too large, the ability of the catalyst to decompose ozone will be slightly reduced. If the amount of zirconium added is too small, the ability of the catalyst to decompose ozone will be greatly reduced.

By comparing Example 1 with Examples 5-6, it can be seen that in the preparation process of the ozone decomposition catalyst of the present invention, the temperature of the calcination treatment will affect the performance of the obtained ozone decomposition catalyst. When the temperature of the calcination treatment is controlled at 350-450°C, the catalytic effect of the obtained ozone decomposition catalyst is better. If the temperature of the calcination treatment is too high, the ability of the catalyst to decompose ozone will be greatly reduced. If the temperature of the calcination treatment is too low, the ability of the catalyst to decompose ozone will be greatly reduced.

The activity comparison diagram of the ozone decomposition catalyst prepared in Example 1 and the ozone decomposition catalyst prepared in Comparative Example 1 is shown in FIG2 . By comparing Example 1 and Comparative Example 1, it can be obtained that a small amount of zirconium is added to the manganese oxide in the present invention. After a 6-hour stability test, Example 1 still has an ozone decomposition ability that is about 25% higher than that of Comparative Example 1.

The applicant declares that the above is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention are within the protection scope and disclosure scope of the present invention.

Claims (11)

1. A method for preparing an ozone decomposition catalyst, characterized in that the preparation method comprises the following steps: (1) mixing an insoluble manganese salt and a soluble zirconium salt with a solvent, stirring and drying the mixture to obtain a mixed material; The soluble zirconium salt includes any one of zirconium nitrate, zirconium chloride or zirconium sulfate or a combination of at least two thereof; the molar ratio of the insoluble manganese salt to the soluble zirconium salt is 1:(0.01-0.03); The insoluble manganese salt comprises manganese carbonate; (2) calcining the mixture obtained in step (1) to obtain the ozone decomposition catalyst; The temperature of the calcination treatment in step (2) is 350-450°C; The calcination time in step (2) is 1.5 to 3 hours. 2. The preparation method according to claim 1, characterized in that the stirring time in step (1) is 0.8~2h. 3. The preparation method according to claim 1, characterized in that the drying method in step (1) comprises rotary evaporation. 4. The preparation method according to claim 1, characterized in that the temperature of the drying treatment in step (1) is 50-70°C. 5. The preparation method according to claim 1, characterized in that a drying treatment is performed before the roasting treatment in step (2). 6. The preparation method according to claim 5, characterized in that the temperature of the drying treatment is 90-120°C. 7. The preparation method according to claim 5, characterized in that the drying time is 10 to 20 hours. 8. The preparation method according to claim 1, characterized in that the calcination treatment in step (2) is followed by screening. 9. The preparation method according to claim 8, characterized in that the mesh size of the sieving process is 40 to 60 meshes. 10. An ozone decomposition catalyst, characterized in that the ozone decomposition catalyst is prepared by the method according to any one of claims 1 to 9. 11. Use of the ozone decomposition catalyst as claimed in claim 10, characterized in that the ozone decomposition catalyst is used to catalytically decompose ozone.