Preparation method of structure-regulated VOCs purification catalyst

Abstract

This invention relates to the field of catalyst technology, and more particularly to a method for preparing a structure-controlled VOCs purification catalyst. The invention involves mixing a cerium salt solution and an alkaline solution, reacting the mixture to obtain a precipitate, and then calcining the precipitate in a reducing atmosphere to obtain the catalyst. This invention prepares mesoporous CeO2 nanorods with adjustable oxygen vacancy cluster concentrations, significantly improving the catalytic purification performance of chlorobenzene. At 340℃, the catalytic efficiency for chlorobenzene reaches as high as 90%, demonstrating high catalytic efficiency; it also exhibits excellent low-temperature catalytic oxidation activity and stability for chlorobenzene, resulting in outstanding overall catalytic performance. This catalyst possesses excellent low-temperature catalytic oxidation activity and stability for chlorobenzene.

Description

Technical Field

[0001] This invention relates to the field of catalyst technology, and in particular to a method for preparing a structure-regulated VOCs purification catalyst. Background Technology

[0002] Volatile organic compounds (VOCs) are major air pollutants, easily causing environmental problems such as photochemical smog and ozone pollution. Catalytic oxidation is the mainstream technology for their efficient degradation, and the development of high-performance catalysts is key to the application of this technology. Cerium dioxide (CeO2) possesses reversible CeO2 oxidation. 3+ / Ce 4+ Redox pairs, abundant surface oxygen vacancies, and excellent oxygen storage and release capabilities have made them core materials for the catalytic oxidation of VOCs, with oxygen vacancies being key active sites for enhancing catalytic performance. However, traditional Ce-based VOCs catalysts mostly rely on single oxygen vacancies for their function, resulting in low active site density and insufficient VOCs adsorption and activation efficiency. Furthermore, existing preparation methods struggle to precisely control the form and concentration of oxygen vacancies, making it impossible to directionally construct oxygen vacancy clusters. In addition, some catalysts suffer from poor thermal stability and rapid performance degradation during recycling, making it difficult to meet the actual needs of industrial VOCs treatment.

[0003] Chlorobenzene compounds, as a typical class of chlorinated volatile organic compounds (CVOCs), are a class of highly toxic and recalcitrant air pollutants, and their efficient catalytic purification is a cutting-edge challenge in the field of environmental catalysis. Catalytic combustion technology is considered the mainstream technology for VOCs treatment due to its advantages of low energy consumption and high purification efficiency. However, metal catalysts suffer from problems such as easy agglomeration and weak resistance to chlorine poisoning. Therefore, developing Ce-based VOCs catalysts with precise controllability of oxygen vacancy cluster concentration, high activity, and excellent stability, especially catalysts suitable for the efficient purification of recalcitrant VOCs such as chlorobenzene, has become an urgent technical problem to be solved in this field. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing a structure-regulated VOCs purification catalyst to solve the problems existing in the prior art.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution: One of the technical solutions of this invention provides a method for preparing a catalyst, comprising the following steps: (1) After mixing the cerium salt solution and the alkaline solution, a reaction is carried out to obtain a precipitate; (2) The precipitate was calcined in a reducing atmosphere to obtain the catalyst.

[0006] Optionally, the cerium salt solution is composed of cerium salt and water; the cerium salt is cerium nitrate; the alkaline solution is composed of alkali and water; the alkali is sodium hydroxide.

[0007] Optionally, the concentration of the cerium salt solution is 160-190 mg / mL; the concentration of the alkaline solution is 260-280 mg / mL.

[0008] Optionally, the volume ratio of the cerium salt solution to the alkaline solution is 1:7.

[0009] Optionally, the mixing time is 20-40 minutes.

[0010] Optionally, the reaction temperature is 90~110℃ and the time is 22~25h.

[0011] Optionally, the precipitate is washed and dried sequentially before calcination; the washing solution is water and ethanol; the drying temperature is 70~90℃ and the time is 12~14h.

[0012] Optionally, the reducing atmosphere is hydrogen; the calcination temperature is 400~600℃, and the calcination time is 1~3h.

[0013] The second technical solution of the present invention provides a catalyst prepared by the above-mentioned catalyst preparation method.

[0014] The third technical solution of the present invention provides the application of the above-mentioned catalyst in the catalytic oxidation of chlorobenzene.

[0015] Compared with the prior art, the present invention has the following beneficial effects: This invention discloses an atmosphere-assisted strategy for preparing mesoporous CeO2 nanorods with tunable oxygen vacancy cluster concentrations, significantly improving the catalytic purification performance of chlorobenzene. The catalyst prepared by this invention allows for controllable oxygen vacancy cluster concentrations, exhibits flexible and tunable structure and properties, demonstrates high catalytic efficiency for chlorobenzene, and possesses abundant catalytic sites; at 340℃, the catalytic efficiency for chlorobenzene reaches as high as 90%, demonstrating high catalytic efficiency; simultaneously, it exhibits excellent low-temperature catalytic oxidation activity and stability for chlorobenzene, resulting in outstanding overall catalytic performance. This catalyst demonstrates excellent low-temperature catalytic oxidation activity and stability for chlorobenzene.

[0016] This invention employs a simple and low-cost preparation method. Oxygen vacancy clusters regulate the dynamic equilibrium of the multi-scale structure of CeO2 through a synergistic "compression-expansion" mechanism, forming a highly efficient Cl-VOCs catalyst. The catalyst's activity and stability can also be significantly improved by controlling different calcination gases, providing a new direction for developing efficient and low-cost Cl-VOCs treatment technologies. Attached Figure Description

[0017] Figure 1 The conversion rates of chlorobenzene (CB) catalyzed by the catalysts prepared in Examples 1, 1, and 2 of this invention at different temperatures are shown.

[0018] Figure 2 The stability curves are for the catalysts prepared in Example 1, Comparative Example 1, and Comparative Example 2 of this invention.

[0019] Figure 3 The carbon dioxide yield of the catalysts prepared in Examples 1, 1, and 2 of this invention at different temperatures. Detailed Implementation

[0020] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0021] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0022] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0023] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be obvious to those skilled in the art. This application specification and embodiments are merely exemplary.

[0024] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0025] All raw materials used in this invention can be obtained commercially or prepared using existing technologies.

[0026] This invention provides a method for preparing a catalyst, comprising the following steps: (1) After mixing the cerium salt solution and the alkaline solution, a reaction is carried out to obtain a precipitate; (2) The precipitate was calcined in a reducing atmosphere to obtain the catalyst.

[0027] Step (1) of the present invention involves adding a cerium salt solution to an alkaline solution to obtain a mixture, heating the mixture to react, cooling and filtering after the reaction is complete to obtain a precipitate.

[0028] In this invention, the cerium salt solution is composed of cerium salt and water; the cerium salt is cerium nitrate, preferably cerium nitrate hexahydrate; the alkaline solution is composed of alkali and water; the alkali is sodium hydroxide.

[0029] In a preferred embodiment of the present invention, cerium salt is dissolved in water to obtain a cerium salt solution.

[0030] In a preferred embodiment of the present invention, the alkali is dissolved in water to obtain an alkaline solution.

[0031] In this invention, the concentration of the cerium salt solution is 160~190 mg / mL, for example, 160 mg / mL, 170 mg / mL, 180 mg / mL or 190 mg / mL, preferably 173.6 mg / mL; the concentration of the alkaline solution is 260~280 mg / mL, for example, 260 mg / mL, 270 mg / mL or 280 mg / mL, preferably 274 mg / mL.

[0032] In this invention, the volume ratio of the cerium salt solution to the alkaline solution is 1:7.

[0033] In this invention, the mixing time is 20 to 40 minutes, for example, 20 minutes, 30 minutes or 40 minutes, preferably 30 minutes.

[0034] In a preferred embodiment of the present invention, the mixing is a stirring mixing, and there are no special limitations on the stirring speed and method, as long as the solution is mixed evenly, magnetic stirring is preferred.

[0035] In this invention, the reaction temperature is 90~110℃, for example, it can be 90℃, 95℃, 100℃, 105℃ or 110℃, etc., preferably 100℃, and the time is 22~25h, for example, it can be 22h, 23h, 24h or 25h, etc., preferably 24h.

[0036] The present invention does not impose any special limitations on the container for the reaction, as long as it can complete the reaction. In the embodiments of the present invention, it is preferred to carry out the reaction in a reaction vessel, which is preferably a reaction vessel with a polytetrafluoroethylene liner.

[0037] In this invention, the precipitate is washed and dried sequentially before calcination; the washing liquid is water and ethanol; the drying temperature is 70~90℃, for example, 70℃, 75℃, 80℃, 85℃ or 90℃, preferably 80℃, and the drying time is 12~14h, for example, 12h, 13h or 14h, preferably 13h.

[0038] In this invention, the reducing atmosphere is hydrogen; the calcination temperature is 400~600℃, for example, 400℃, 450℃, 500℃, 550℃ or 600℃, preferably 500℃; the calcination time is 1~3h, for example, 1h, 2h or 3h, preferably 2h.

[0039] The present invention also provides a catalyst prepared by the above-described method.

[0040] The present invention also provides the application of the above-mentioned catalyst in the catalytic oxidation of chlorobenzene.

[0041] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0042] Example 1 (1) Dissolve 1.736g of cerium nitrate hexahydrate in 10ml of deionized water to form a cerium nitrate hexahydrate solution; dissolve 19.20g of sodium hydroxide in 70ml of deionized water to form a sodium hydroxide solution; (2) Slowly add the cerium nitrate hexahydrate solution to the sodium hydroxide solution and stir magnetically for 30 minutes at room temperature to obtain a mixture; (3) Transfer the mixture formed in (2) to a 250ml polytetrafluoroethylene-lined reactor and heat it in an oven at 100°C for 24 hours; (4) After cooling the mixture treated in (3) to room temperature, filter to obtain a white precipitate, wash it repeatedly with deionized water and ethanol 3 times, and dry it at 80°C for 13 hours to obtain a dry powder; (5) The powder formed in (4) is calcined at 500°C for 2 hours in a hydrogen atmosphere to obtain the catalyst.

[0043] Comparative Example 1 (1) Dissolve 1.736g of cerium nitrate hexahydrate in 10ml of deionized water to form a cerium nitrate hexahydrate solution; dissolve 19.20g of sodium hydroxide in 70ml of deionized water to form a sodium hydroxide solution; (2) Slowly add the cerium nitrate hexahydrate solution to the sodium hydroxide solution and stir magnetically for 30 minutes at room temperature to obtain a mixture; (3) Transfer the mixture formed in (2) to a 250ml polytetrafluoroethylene-lined reactor and heat it in an oven at 100°C for 24 hours; (4) After cooling the mixture treated in (3) to room temperature, filter to obtain a white precipitate, wash it repeatedly with deionized water and ethanol 3 times, and dry it at 80°C for 13 hours to obtain a dry powder; (5) The powder formed in (4) is calcined at 500°C for 2 hours in an ammonia atmosphere to obtain the catalyst.

[0044] Comparative Example 2 (1) Dissolve 1.736g of cerium nitrate hexahydrate in 10ml of deionized water to form a cerium nitrate hexahydrate solution; dissolve 19.20g of sodium hydroxide in 70ml of deionized water to form a sodium hydroxide solution; (2) Slowly add the cerium nitrate hexahydrate solution to the sodium hydroxide solution and stir magnetically for 30 minutes at room temperature to obtain a mixture; (3) Transfer the mixture formed in (2) to a 250ml polytetrafluoroethylene-lined reactor and heat it in an oven at 100°C for 24 hours; (4) After cooling the mixture treated in (3) to room temperature, filter to obtain a white precipitate, wash it repeatedly with deionized water and ethanol 3 times, and dry it at 80°C for 13 hours to obtain a dry powder; (5) The powder formed in (4) is calcined in air at 500°C for 2 hours to obtain the catalyst.

[0045] Performance testing The catalytic oxidation activity of the catalysts prepared in Example 1 and Comparative Examples 1-2 was tested as follows: 0.1 g of catalyst (40-60 mesh) was placed in a fixed-bed reactor. Liquid chlorobenzene was bubbled into the reaction system using compressed air to simulate gas. The concentration of chlorobenzene was controlled at 500 ± 50 ppm by air, the total gas flow rate was 50 ml / min, and the gas space velocity was 30000 mL·g. -1 ·h -1 Real-time monitoring of chlorobenzene and CO2 concentrations via online chromatography: Figure 1 The figures show the conversion rates of chlorobenzene (CB) catalytically oxidized by the catalysts prepared in Examples 1, 1, and 2 of this invention at different temperatures. As can be seen from the figures, the catalyst prepared in Example 1 exhibits superior chlorobenzene oxidation ability compared to Comparative Examples 1 and 2. The catalyst prepared in Example 1 achieved a chlorobenzene conversion rate of 90% at 340°C.

[0046] Figure 2The figures show the stability curves of the catalysts prepared in Example 1, Comparative Example 1, and Comparative Example 2 of this invention. The catalyst prepared in Example 1 exhibits superior chlorobenzene oxidation ability and better stability compared to Comparative Examples 1 and 2.

[0047] Figure 3 The carbon dioxide yield of the catalysts prepared in Examples 1, 1, and 2 of this invention at different temperatures. Figure 3 As can be seen, the catalyst prepared in Example 1 exhibits superior chlorobenzene oxidation ability and better stability compared with Comparative Examples 1 and 2.

[0048] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a catalyst, characterized in that, Includes the following steps: (1) After mixing the cerium salt solution and the alkaline solution, a reaction is carried out to obtain a precipitate; (2) The precipitate was calcined in a reducing atmosphere to obtain the catalyst.

2. The method for preparing the catalyst according to claim 1, characterized in that, The cerium salt solution is composed of cerium salt and water; the cerium salt is cerium nitrate; the alkaline solution is composed of alkali and water; the alkali is sodium hydroxide.

3. The method for preparing the catalyst according to claim 1, characterized in that, The concentration of the cerium salt solution is 160~190 mg / mL; the concentration of the alkaline solution is 260~280 mg / mL.

4. The method for preparing the catalyst according to claim 1, characterized in that, The volume ratio of the cerium salt solution to the alkaline solution is 1:

7.

5. The method for preparing the catalyst according to claim 1, characterized in that, The mixing time is 20-40 minutes.

6. The method for preparing the catalyst according to claim 1, characterized in that, The reaction is carried out at a temperature of 90-110°C for 22-25 hours.

7. The method for preparing the catalyst according to claim 1, characterized in that, Before calcination, the precipitate is washed and dried sequentially; the washing solution is water and ethanol; the drying temperature is 70~90℃ and the time is 12~14h.

8. The method for preparing the catalyst according to claim 1, characterized in that, The reducing atmosphere is hydrogen; the calcination temperature is 400~600℃, and the calcination time is 1~3h.

9. The catalyst prepared by the method according to any one of claims 1 to 8.

10. The application of the catalyst as described in claim 9 in the catalytic oxidation of chlorobenzene.

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