Catalyst for catalytic combustion of vocs and method of making same

Abstract

The application relates to the field of catalysts, and particularly discloses a catalyst for VOCs catalytic combustion and a preparation method thereof. The preparation method of the catalyst for VOCs catalytic combustion comprises the following steps: (1) uniformly mixing a cerium source, a noble metal source, a complexing agent, water and ethylene glycol, heating at 50-100 DEG C for a first preset time, and performing solid-liquid separation to obtain a catalyst precursor; wherein the cerium source and the noble metal source are both soluble in water; (2) calcining the catalyst precursor at 400-500 DEG C for a second preset time to obtain a catalyst product. The preparation method is simple, the catalyst has strong catalytic performance, and the catalyst can be applied to the catalytic combustion of various VOCs.

Description

Technical Field

[0001] This invention relates to the field of catalysts, and more particularly to a catalyst for the catalytic combustion of VOCs and a method for preparing the same. Background Technology

[0002] Volatile organic compounds (VOCs) are O3 and PM2.5. 2.5 Key precursors to VOCs have caused serious harm to the ecological environment and human health. For the treatment of VOCs, catalytic combustion is one of the mainstream technologies for treating volatile organic compounds, characterized by complete catalytic oxidation and pollution-free combustion products. Its core lies in the development and improvement of high-performance catalysts.

[0003] In existing technologies, supported noble metal catalysts are often used as catalysts for catalytic combustion, which are mainly obtained by supporting noble metals on a support (such as activated carbon, perovskite, cerium dioxide, etc.). Currently, the preparation method of this catalyst is often a stepwise synthesis, that is, first synthesizing the support, and then loading the noble metal onto the support. This preparation process is complex. Moreover, currently supported noble metal catalysts often have a narrow range of applications; for example, while exhibiting good catalytic activity for toluene, they often show weak catalytic activity for ethyl acetate, resulting in a limited range of applications. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a catalyst for the catalytic combustion of VOCs and its preparation method, which has a simple process, strong catalytic activity, and is suitable for the catalytic combustion of various VOCs.

[0005] To address the technical problem of this invention, this invention provides a method for preparing a catalyst for the catalytic combustion of VOCs, characterized by comprising the following steps: (1) A cerium source, a noble metal source, a ligand, water and ethylene glycol are mixed evenly and heated at 50~100℃ for a first preset time. The solid and liquid are separated to obtain a catalyst precursor. The cerium source and the noble metal source are both soluble in water. (2) The catalyst precursor is calcined at 400~500℃ for a second preset time to obtain the finished catalyst product.

[0006] As an improvement to the above technical solution, the cerium source is selected from one or more of cerium nitrate, hydrated cerium nitrate, cerium acetate, hydrated cerium acetate, cerium chloride, hydrated cerium chloride, cerium sulfate, cerium ammonium acetate, and cerium ammonium sulfate. The ligand is selected from one or more of citric acid, citric acid monohydrate, sodium citrate, oxalic acid, tartaric acid, and oxalic acid. The precious metal source is selected from one or more of platinum, palladium, and ruthenium sources; The platinum source is selected from one or more of chloroplatinic acid, potassium chloroplatinate, sodium chloroplatinate, platinum nitrate, platinum sulfate, and tetraammineplatinum chloride. The palladium source is selected from one or more of palladium chloride, palladium acetate, palladium sulfate, and tetraamminepalladium chloride; The ruthenium source is selected from one or more of ruthenium chlororuthenium acid, potassium ruthenium chlororuthenium, sodium ruthenium chlororuthenium, ruthenium chloride, ruthenium nitrate, and ruthenium acetate.

[0007] As an improvement to the above technical solution, the cerium source is selected from cerium nitrate and / or hydrated cerium nitrate; The ligand is selected from citric acid and / or citric acid monohydrate; The precious metal source is selected from one or more of platinum, palladium, and ruthenium sources; The platinum source is selected as platinum nitrate; The palladium source is palladium acetate; The ruthenium source is ruthenium chloride.

[0008] As an improvement to the above technical solution, the molar ratio of the cerium source and the ligand is 1:1.5~3; The molar ratio of cerium in the cerium source to the volume of ethylene glycol is 2~20 mmol: 0.2~3 mL; The molar ratio of cerium in the cerium source to the volume of water is 2~20 mmol: 5~20 mL; The weight of the precious metal element in the precious metal source is 0.05% to 1% of the weight of cerium in the cerium source; The first preset time is 5~15 hours; The second preset time is 2~8 hours.

[0009] As an improvement to the above technical solution, the molar ratio of the cerium source and the ligand is 1:2; The molar ratio of cerium in the cerium source to the volume of ethylene glycol is 5 mmol: 1 mL; The molar amount of cerium in the cerium source is in the ratio of the volume of water to 5 mmol: 10 mL. The weight of the precious metal element in the precious metal source is 0.4% to 0.8% of the weight of cerium in the cerium source; The first preset time is 12 hours; The second preset time is 4 hours.

[0010] As an improvement to the above technical solution, in step (1), the cerium source, the noble metal source, the coordinating agent, the additive, the water and the ethylene glycol are mixed evenly. The additive is selected from one or more of sodium borohydride, potassium borohydride, and lithium borohydride; The molar ratio of cerium in the cerium source to the molar ratio of the additive is 2~20:0.1~2.

[0011] As an improvement to the above technical solution, sodium borohydride is selected as the additive; The molar ratio of cerium in the cerium source to the molar ratio of the additive is 5:0.2~0.5.

[0012] As an improvement to the above technical solution, the precious metal source is selected from platinum source and palladium source, the platinum source is selected from platinum nitrate, and the palladium source is selected from palladium acetate; the weight ratio of platinum in the platinum source to the weight of palladium in the palladium source is 1:0.8~1.5.

[0013] As an improvement to the above technical solution, the precious metal source is selected from platinum source and ruthenium source, the platinum source is selected from platinum nitrate, and the ruthenium source is selected from ruthenium chloride; the weight ratio of platinum in the platinum source to the weight of ruthenium in the ruthenium source is 1:0.8~1.5.

[0014] Accordingly, the present invention also discloses a catalyst for the catalytic combustion of VOCs, which is prepared by the above-described method for preparing a catalyst for the catalytic combustion of VOCs.

[0015] Implementing this invention has the following beneficial effects: In one embodiment of the present invention, a method for preparing a catalyst for the catalytic combustion of VOCs involves a one-step process to load a noble metal onto a support, forming stable composite nanoparticles. This enhances the interaction between the noble metal and the support, improves the catalytic effect, and simplifies the preparation process. Furthermore, the catalyst prepared by this invention exhibits excellent catalytic combustion effects on various types of VOCs (toluene, ethyl acetate, chlorobenzene, etc.). Attached Figure Description

[0016] Figure 1 These are performance graphs of the catalysts obtained in Examples 1 to 4 of this invention catalyzing toluene. Figure 2 This is a graph showing the performance of the catalysts obtained in Example 2 and Comparative Example 1 of this invention in catalyzing toluene. Figure 3 This is a diagram showing the water resistance of the catalyst obtained in Example 2 of this invention; Figure 4 This is a diagram showing the water resistance of the catalyst obtained in Comparative Example 1 of the present invention; Figure 5 This is a SEM image of the catalyst obtained in Example 2 of the present invention. Detailed Implementation

[0017] To facilitate understanding of the present invention, it will be described in more detail below. However, it should be understood that the present invention can be implemented in many different forms and is not limited to the embodiments or examples described herein. Rather, these embodiments or examples are provided to make the disclosure of the present invention more thorough and complete.

[0018] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the specification of this invention is for the purpose of describing particular embodiments or examples only and is not intended to limit the invention. The optional range of the term "and / or" as used herein includes any one of two or more of the related listed items, as well as any and all combinations of the related listed items, including any two related listed items, any more related listed items, or a combination of all related listed items.

[0019] The following embodiments are provided for the purpose of illustrating various embodiments of the present invention and are not intended to limit the invention in any way. Those skilled in the art will understand that variations and other uses thereof, as defined in the claims, are included within the spirit and scope of the invention. In this invention, terms such as "first aspect," "second aspect," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or quantity, nor should they be construed as implicitly indicating the importance or quantity of the indicated technical features.

[0020] In this invention, the technical features described in an open-ended manner include both closed-ended technical solutions composed of the listed features and open-ended technical solutions that include the listed features.

[0021] Unless otherwise specified, the percentage content mentioned in this invention refers to mass percentage for solid-liquid mixtures and solid-phase-solid mixtures, and volume percentage for liquid-phase-liquid mixtures. Unless otherwise specified, the percentage concentration mentioned in this invention refers to the final concentration. The final concentration refers to the proportion of the added component in the system after its addition. Unless otherwise specified, the temperature parameters in this invention allow for both isothermal treatment and treatment within a certain temperature range. Isothermal treatment allows temperature fluctuations within the precision range controlled by the instrument.

[0022] As a first aspect of the present invention, the present invention provides a method for preparing a catalyst for the catalytic combustion of VOCs, comprising the following steps: (1) The cerium source, noble metal source, ligand, water and ethylene glycol are mixed evenly and heated at 50~100℃ for a first preset time. The solid-liquid separation is then performed to obtain the catalyst precursor. (2) The catalyst precursor is calcined at 400~500℃ for a second preset time to obtain the finished catalyst.

[0023] Based on the above preparation method, a one-step process is used to load noble metals onto a support, forming stable composite nanoparticles. This enhances the interaction between the noble metals and the support, thereby improving the catalytic effect. Specifically, the inventors unexpectedly discovered that, compared to catalysts synthesized via a two-step process of first preparing a cerium oxide support and then loading noble metals, the catalyst prepared in this invention exhibits significantly improved catalytic combustion performance for various types of VOCs (toluene, ethyl acetate, chlorobenzene, etc.).

[0024] Specifically, in step (1), the cerium source is a water-soluble cerium salt, which can be, for example, cerium nitrate, hydrated cerium nitrate (such as cerium nitrate hexahydrate, cerium ammonium nitrate dihydrate), cerium acetate, hydrated cerium acetate (such as cerium acetate tetrahydrate, cerium acetate sesquihydrate), cerium chloride, hydrated cerium chloride (such as cerium chloride hexahydrate, cerium chloride heptahydrate), cerium sulfate, cerium sulfate hydrate, cerium ammonium acetate, cerium ammonium sulfate, etc., but is not limited to these. Preferably, in some embodiments, the cerium source is selected from one or more of cerium nitrate, hydrated cerium nitrate, cerium acetate, hydrated cerium acetate, cerium chloride, and hydrated cerium chloride. More preferably, the cerium source is selected from cerium nitrate or cerium nitrate hexahydrate.

[0025] Specifically, in step (1), the precious metal source is selected from one or more of platinum, palladium, ruthenium, and rhodium, but is not limited thereto. The platinum source is selected from one or more of chloroplatinic acid, potassium chloroplatinate, sodium chloroplatinate, platinum nitrate or its hydrate, platinum sulfate or its hydrate, and tetraammineplatinum chloride, but is not limited thereto. Preferably, in some embodiments, the platinum source is selected from chloroplatinic acid, platinum nitrate, or platinum nitrate hydrate. More preferably, the platinum source is selected from platinum nitrate.

[0026] The palladium source is selected from one or more of palladium chloride or its hydrate, palladium acetate or its hydrate, palladium sulfate or its hydrate, and tetraamminepalladium chloride, but is not limited thereto. Preferably, in some embodiments, the palladium source is selected from palladium acetate or its hydrate, or palladium chloride or its hydrate. More preferably, the palladium source is selected from palladium acetate.

[0027] The ruthenium source is selected from one or more of ruthenium chlororuthenic acid, potassium chlororuthenate, sodium chlororuthenate, ruthenium chloride or its hydrate, ruthenium nitrate or its hydrate, and ruthenium acetate or its hydrate, but is not limited thereto. Preferably, in some embodiments, the ruthenium source is ruthenium chloride or its hydrate, or ruthenium chlororuthenic acid. More preferably, the ruthenium source is ruthenium chloride.

[0028] The rhodium source is selected from one or more of rhodium chloride or its hydrate, sodium hexachlororhodium, and potassium hexachlororhodium, but is not limited thereto. Preferably, in some embodiments, the rhodium source is rhodium chloride or its hydrate.

[0029] Specifically, in step (1), the ligand is selected from one or more of citric acid, citric acid monohydrate, sodium citrate, oxalic acid, tartaric acid, and oxalic acid, but is not limited thereto. Preferably, in some embodiments, the ligand is selected from citric acid or citric acid monohydrate.

[0030] Specifically, in step (1), the molar ratio of cerium source to ligand is 1:(1.5~3), exemplarily 1:1.8, 1:2, 1:2.4, 1:2.6 or 1:2.8, but not limited thereto. Preferably, the molar ratio of cerium source to ligand is 1:(1.5~2.5), more preferably 1:(1.8~2.2), and even more preferably 1:2.

[0031] Specifically, in step (1), the molar ratio of cerium in the cerium source to the volume of ethylene glycol is 2-20 mmol: 0.2-3 mL; exemplary ratios are 5 mmol: 0.7 mL, 9 mmol: 1.1 mL, 13 mmol: 1.5 mL, 13 mmol: 1.9 mL, 17 mmol: 2.3 mL, or 19 mmol: 2.7 mL. Preferably, the molar ratio of cerium in the cerium source to the volume of ethylene glycol is 3-10 mmol: 0.5-2 mL, more preferably 3-8 mmol: 0.5-1.5 mL; and even more preferably 5 mmol: 1 mL.

[0032] Specifically, in step (1), the molar ratio of cerium in the cerium source to the volume of water is 2~20 mmol: 5~20 mL; exemplary ratios are 3 mmol: 8 mL, 7 mmol: 12 mL, 9 mmol: 15 mL, 11 mmol: 18 mL or 19 mmol: 20 mL; preferably 3~10 mmol: 6~15 mL, more preferably 3~8 mmol: 8~12 mL; and even more preferably 5 mmol: 10 mL.

[0033] Specifically, in step (1), the weight of the precious metal element in the precious metal source is 0.05% to 1% of the weight of cerium in the cerium source; exemplary values ​​are 0.08%, 0.1%, 0.25%, 0.4%, 0.55%, 0.7%, or 0.85%, but not limited thereto. Preferably, in some embodiments, the weight of the precious metal element in the precious metal source is 0.4% to 0.8% of the weight of cerium in the cerium source, more preferably 0.4% to 0.7%, and even more preferably 0.4% to 0.5%.

[0034] For example, in step (1), the temperature of the heating reaction is 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C or 90°C, but is not limited thereto. Preferably it is 60°C to 90°C, more preferably it is 70°C to 85°C.

[0035] Specifically, in step (1), the first preset time is 5 to 15 hours, for example 6 hours, 8 hours, 10 hours, 12 hours or 14 hours; preferably 8 to 14 hours, more preferably 10 to 12 hours.

[0036] Preferably, in some embodiments, in step (1), the cerium source, the noble metal source, the coordinating agent, the additive, water and ethylene glycol are mixed evenly; wherein, the additive is selected from one or more of sodium borohydride, potassium borohydride and lithium borohydride; by introducing boron-containing additives, the electron density of noble metals can be reduced by boron modification, and the ability to activate molecular oxygen can be enhanced, thereby improving the catalytic performance. Not only is the catalytic performance for a variety of VOCs improved, but the inventors also unexpectedly discovered that when boron-containing additives are introduced, the water resistance of the prepared catalyst is greatly enhanced, which makes the catalyst of the present invention suitable for the treatment of some high humidity industrial waste gases.

[0037] Preferably, in some embodiments, in step (1), the precious metal source is a platinum source and a palladium source, the platinum source is platinum nitrate, and the palladium source is palladium acetate; the weight ratio of platinum in the platinum source to the weight of palladium in the palladium source is 1:0.8~1.5. Alternatively, the precious metal source is a platinum source and a ruthenium source, the platinum source is platinum nitrate, and the ruthenium source is ruthenium chloride; the weight ratio of platinum in the platinum source to the weight of ruthenium in the ruthenium source is 1:0.8~1.5. By using the above-mentioned precious metal source, the conversion temperature (T0) of different volatile organic compounds can be reduced. 50 T 90 This invention simplifies the catalytic combustion process. It's important to note that traditional catalysts for catalytic combustion often focus on the conversion efficiency of a single VOC. However, the inventors discovered during experiments that different VOCs exhibit significant differences in reactivity on the same catalyst, leading to substantial differences in their conversion temperatures. For example, a certain catalyst has a T90 of 200°C for toluene but a T90 as high as 260°C for chlorobenzene. This large T90 difference makes it difficult to achieve simultaneous and efficient removal of multiple VOCs within a narrow temperature window during catalytic combustion. Either a lower combustion temperature (e.g., 200°C) results in high toluene removal but low chlorobenzene removal, or a higher combustion temperature (e.g., 260°C) leads to high removal rates for both but also high energy consumption and operating costs. In this invention, by using a boron-containing additive, a one-step synthesis method, and specific types and ratios of precious metals, the differences in T50 and T90 for different VOCs are effectively reduced, enabling simultaneous, low-energy removal of multiple VOCs within a narrower temperature window.

[0038] Specifically, in step (2), the calcination temperature is 400~500℃, exemplarily 420℃, 440℃, 460℃, 480℃ or 490℃, but not limited thereto. Preferably it is 440~500℃.

[0039] Specifically, in step (2), the second preset time is 2~8h, 2.5h, 4h, 5.5h, 7h or 7.5h, but is not limited to this. Preferably it is 2~5h, more preferably 4h.

[0040] Accordingly, as a second aspect of the present invention, a catalyst for the catalytic combustion of VOCs is also disclosed, which is prepared by the above-described preparation method. By directly mixing a cerium source, a noble metal source, a coordinating agent, water, and ethylene glycol, followed by heating and calcination, a one-step synthesis of the catalyst yields composite and stable nanoparticles, improving the catalytic effect and simplifying the preparation steps. Furthermore, the catalyst of the present invention significantly enhances the catalytic combustion performance of various types of VOCs (toluene, ethyl acetate, chlorobenzene, etc.).

[0041] Accordingly, as a third aspect of the present invention, the present invention also provides a method for combustion of industrial waste gas containing VOCs, which includes the step of mixing the above-mentioned catalyst with the industrial waste gas for catalytic combustion.

[0042] More specifically, the catalyst is first granulated into 40-60 mesh particles, and then mixed with industrial waste gas for catalytic combustion, but is not limited to this.

[0043] The present invention will be further described below with reference to specific embodiments: Example 1 This embodiment provides a method for preparing a catalyst for the catalytic combustion of VOCs, comprising: 0.005 mol of cerium source (cerium nitrate hexahydrate) and platinum source (platinum nitrate) were dissolved in 10 mL of deionized water, followed by the addition of 0.01 mol of citric acid monohydrate and 1 mL of ethylene glycol. The mixture was stirred and mixed for 30 min, and then reacted at 80 °C for 12 h to obtain the catalyst precursor. The weight of platinum in platinum nitrate was 0.0407% of the weight of cerium in the cerium source (corresponding to 0.5 wt% of CeO2).

[0044] The catalyst precursor was placed in a muffle furnace and heated to 400°C at a heating rate of 5°C / min, and held at that temperature for 4 hours to obtain the finished catalyst.

[0045] Example 2 This embodiment provides a method for preparing a catalyst for the catalytic combustion of VOCs, comprising: 0.005 mol of cerium source (cerium nitrate hexahydrate) and platinum source (platinum nitrate) were dissolved in 10 mL of deionized water, followed by the addition of 0.01 mol of citric acid monohydrate and 1 mL of ethylene glycol. After dissolution, 0.5 mmol of sodium borohydride was added, and the mixture was stirred for 30 min. The reaction was then carried out at 80 °C for 12 h to obtain the catalyst precursor. The weight of platinum in platinum nitrate was 0.0407% of the weight of cerium in the cerium source (corresponding to 0.5 wt% of CeO2).

[0046] The catalyst precursor was placed in a muffle furnace and heated to 400°C at a heating rate of 5°C / min, and held at that temperature for 4 hours to obtain the finished catalyst.

[0047] Example 3 This embodiment provides a method for preparing a catalyst for VOCs combustion. The difference between this method and Example 2 is that the amount of sodium borohydride added is 0.2 mmol, while the rest is the same as in Example 2.

[0048] Example 4 This embodiment provides a method for preparing a catalyst for the catalytic combustion of VOCs. The difference between this method and Example 2 is that the amount of sodium borohydride added is 1 mmol, while the rest are the same as in Example 2.

[0049] Example 5 This embodiment provides a method for preparing a catalyst for the catalytic combustion of VOCs, comprising: 0.005 mol of cerium source (cerium nitrate hexahydrate) and palladium source (palladium nitrate) were dissolved in 10 mL of deionized water, followed by the addition of 0.01 mol of citric acid monohydrate and 1 mL of ethylene glycol. The mixture was stirred and mixed for 30 min, and then reacted at 80 °C for 12 h to obtain the catalyst precursor. The weight of palladium in the palladium nitrate was 0.0407% of the weight of cerium in the cerium source (corresponding to 0.5 wt% of CeO2).

[0050] The catalyst precursor was placed in a muffle furnace and heated to 400°C at a heating rate of 5°C / min, and held at that temperature for 4 hours to obtain the finished catalyst.

[0051] Example 6 This embodiment provides a method for preparing a catalyst for the catalytic combustion of VOCs, comprising: 0.005 mol of cerium source (cerium nitrate hexahydrate) and palladium source (palladium nitrate) were dissolved in 10 mL of deionized water, followed by the addition of 0.01 mol of citric acid monohydrate and 1 mL of ethylene glycol. After dissolution, 0.5 mmol of sodium borohydride was added, and the mixture was stirred for 30 min. The reaction was then carried out at 80 °C for 12 h to obtain the catalyst precursor. The weight of palladium in the palladium nitrate was 0.0407% of the weight of cerium in the cerium source (corresponding to 0.5 wt% of CeO2).

[0052] The catalyst precursor was placed in a muffle furnace and heated to 400°C at a heating rate of 5°C / min, and held at that temperature for 4 hours to obtain the finished catalyst.

[0053] Example 7 This embodiment provides a method for preparing a catalyst for the catalytic combustion of VOCs, comprising: 0.005 mol of cerium source (cerium nitrate hexahydrate) and ruthenium source (ruthenium chloride) were dissolved in 10 mL of deionized water, followed by the addition of 0.01 mol of citric acid monohydrate and 1 mL of ethylene glycol. After dissolution, 0.5 mmol of sodium borohydride was added, and the mixture was stirred for 30 min. The reaction was then carried out at 80 °C for 12 h to obtain the catalyst precursor. The weight of ruthenium in the ruthenium chloride was 0.0407% of the weight of cerium in the cerium source (corresponding to 0.5 wt% of CeO2).

[0054] The catalyst precursor was placed in a muffle furnace and heated to 400°C at a heating rate of 5°C / min, and held at that temperature for 4 hours to obtain the finished catalyst.

[0055] Example 8 This embodiment provides a method for preparing a catalyst for the catalytic combustion of VOCs, comprising: 0.005 mol of cerium source (cerium nitrate hexahydrate), platinum source (platinum nitrate), and palladium source (palladium nitrate) were dissolved in 10 mL of deionized water. Then, 0.01 mol of citric acid monohydrate and 1 mL of ethylene glycol were added. After dissolution, 0.5 mmol of sodium borohydride was added, and the mixture was stirred for 30 min. The reaction was then carried out at 80 °C for 12 h to obtain the catalyst precursor. The weight of platinum in platinum nitrate was 0.0203% of the weight of cerium in the cerium source, and the weight of palladium in palladium nitrate was 0.0203% of the weight of cerium in the cerium source.

[0056] The catalyst precursor was placed in a muffle furnace and heated to 400°C at a heating rate of 5°C / min, and held at that temperature for 4 hours to obtain the finished catalyst.

[0057] Example 9 This embodiment provides a method for preparing a catalyst for the catalytic combustion of VOCs, comprising: 0.005 mol of cerium source (cerium nitrate hexahydrate), platinum source (platinum nitrate), and ruthenium source (ruthenium chloride) were dissolved in 10 mL of deionized water. Then, 0.01 mol of citric acid monohydrate and 1 mL of ethylene glycol were added. After dissolution, 0.5 mmol of sodium borohydride was added, and the mixture was stirred for 30 min. The reaction was then carried out at 80 °C for 12 h to obtain the catalyst precursor. The weight of platinum in platinum nitrate was 0.0203% of the weight of cerium in the cerium source, and the weight of ruthenium in ruthenium chloride was 0.0203% of the weight of cerium in the cerium source.

[0058] The catalyst precursor was placed in a muffle furnace and heated to 400°C at a heating rate of 5°C / min, and held at that temperature for 4 hours to obtain the finished catalyst.

[0059] Comparative Example 1 This comparative example provides a method for preparing a catalyst, which specifically includes: (1) Dissolve 0.005 mol of cerium nitrate hexahydrate in 10 mL of deionized water, then add 0.01 mol of citric acid monohydrate and 1 mL of ethylene glycol, stir for 30 min, and after dissolution, react in an oil bath at 80 °C for 12 h. Place the obtained sample in a muffle furnace and calcine it at 400 °C for 4 h at a heating rate of 5 °C / min to obtain the cerium dioxide support.

[0060] (2) Take 0.8 g of the support prepared in step (1) and disperse it in 10 mL of platinum nitrate solution (the amount of platinum in the platinum nitrate is 0.5% of the mass of the cerium dioxide support), and stir for 30 min. Add 5 mL of 0.1 M sodium borohydride solution dropwise under stirring, and stir for 10 min. After washing and drying overnight, place the obtained sample in a muffle furnace and calcine it to 400 °C at a heating rate of 5 °C / min for 4 h to obtain the final cerium dioxide supported noble metal catalyst prepared by wet impregnation method.

[0061] Comparative Example 2 This comparative example provides a method for preparing a catalyst, which specifically includes: (1) Dissolve 0.005 mol of cerium nitrate hexahydrate in 10 mL of deionized water, then add 0.01 mol of citric acid monohydrate and 1 mL of ethylene glycol, stir for 30 min, and after dissolution, react in an oil bath at 80 °C for 12 h. Place the obtained sample in a muffle furnace and calcine at 400 °C for 4 h at a heating rate of 5 °C / min to obtain the cerium dioxide support.

[0062] (2) Take 0.8 g of the cerium dioxide (CeO2) support prepared in step (1) and disperse it in 10 mL of palladium nitrate (the amount of palladium in palladium nitrate is 0.25% of the mass of the cerium dioxide support) and platinum nitrate (the amount of platinum in platinum nitrate is 0.25% of the mass of the cerium dioxide support) solution, and stir for 30 min. Under stirring conditions, add 5 mL of 0.1 M sodium borohydride solution dropwise and stir for 10 min. After washing and drying overnight, place the obtained sample in a muffle furnace and calcine it to 400 ℃ at a heating rate of 5 ℃ / min for 4 h to obtain the final cerium dioxide supported noble metal catalyst (denoted as Pt) prepared by wet impregnation method. 0.25 Pd 0.25 / CeO2-0.5-WI).

[0063] The catalysts obtained in Examples 1 to 9 and Comparative Examples 1 to 2 were tested using the following specific testing methods: The prepared catalyst powder was compressed into tablets and ground into 40-60 mesh particles. Catalytic combustion experiments were then conducted under the following conditions: 100 mg of catalyst was loaded into the reactor, and synthesis air (20 vol% O2, 80 vol% N2) with a VOCs (toluene / ethyl acetate / chlorobenzene) concentration of (1000 ppm / 1000 ppm / 500 ppm) was introduced at a flow rate of 100 mL / min. The mass hourly space velocity (WHSV) was 60000 mL / (g·h). The concentration of VOCs at the reactor outlet was measured, and the VOCs conversion rate was calculated. The VOCs conversion rate is defined as the volume percentage of VOCs entering the reactor that is converted, i.e., the difference in volume percentage of VOCs between the inlet and outlet gases relative to the volume percentage of VOCs in the inlet gas. Where T... 50 With T 90 The temperatures at which VOCs conversion rates are 50% and 90% are indicated. Specific test results are shown in the table below:

[0064] A comparison of Example 1 and Comparative Example 1 shows that the one-step synthesis method of this application can effectively improve the catalytic performance of the catalyst for various VOCs. A comparison of Examples 1-4 and Comparative Example 1 shows that introducing NaBH4 into the reactants not only effectively improves the catalytic performance (see Example 1). Figures 1-2 Furthermore, it improved the catalyst's water resistance (see...). Figures 3-4 Furthermore, SEM images showed that B and Pt were uniformly dispersed in the catalyst. A comparison of Examples 2 and 6-9 demonstrates that by employing multiple noble metal sources in specific proportions, the To ratio among various VOCs can be reduced. 90 This improves combustion efficiency.

[0065] The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as the combination of these technical features does not contradict each other, it should be considered within the scope of this specification. The above embodiments only illustrate several implementation methods of the present invention to facilitate a specific and detailed understanding of the technical solution of the present invention, but should not be construed as limiting the scope of protection of the invention patent. It should be noted that for those skilled in the art, several modifications and improvements can be made without departing from the concept of the present invention, and these all fall within the protection scope of the present invention.

[0066] It should be understood that any technical solutions obtained by those skilled in the art based on the technical solutions provided in this invention through logical analysis, reasoning, or limited experimentation are all within the scope of protection of the claims of this invention. Therefore, the scope of protection of this patent should be determined by the content of the appended claims, and the specification and drawings can be used to interpret the content of the claims.

Claims

1. A method for preparing a catalyst for the catalytic combustion of VOCs, characterized in that, Includes the following steps: (1) A cerium source, a noble metal source, a ligand, water and ethylene glycol are mixed evenly and heated at 50~100℃ for a first preset time. The solid and liquid are separated to obtain a catalyst precursor. The cerium source and the noble metal source are both soluble in water. (2) The catalyst precursor is calcined at 400~500℃ for a second preset time to obtain the finished catalyst product.

2. The method for preparing the catalyst for VOCs catalytic combustion as described in claim 1, characterized in that, The cerium source is selected from one or more of cerium nitrate, hydrated cerium nitrate, cerium acetate, hydrated cerium acetate, cerium chloride, hydrated cerium chloride, cerium sulfate, cerium ammonium acetate, and cerium ammonium sulfate. The ligand is selected from one or more of citric acid, citric acid monohydrate, sodium citrate, oxalic acid, tartaric acid, and oxalic acid. The precious metal source is selected from one or more of platinum, palladium, and ruthenium sources; The platinum source is selected from one or more of chloroplatinic acid, potassium chloroplatinate, sodium chloroplatinate, platinum nitrate, platinum sulfate, and tetraammineplatinum chloride. The palladium source is selected from one or more of palladium chloride, palladium acetate, palladium sulfate, and tetraamminepalladium chloride; The ruthenium source is selected from one or more of ruthenium chlororuthenium acid, potassium ruthenium chlororuthenium, sodium ruthenium chlororuthenium, ruthenium chloride, ruthenium nitrate, and ruthenium acetate.

3. The method for preparing the catalyst for VOCs catalytic combustion as described in claim 1, characterized in that, The cerium source is selected from cerium nitrate and / or hydrated cerium nitrate; The ligand is selected from citric acid and / or citric acid monohydrate; The precious metal source is selected from one or more of platinum, palladium, and ruthenium sources; The platinum source is selected as platinum nitrate; The palladium source is palladium acetate; The ruthenium source is ruthenium chloride.

4. The method for preparing the catalyst for VOCs catalytic combustion as described in claim 1, characterized in that, The molar ratio of the cerium source to the ligand is 1:1.5~3; The molar ratio of cerium in the cerium source to the volume of ethylene glycol is 2~20 mmol: 0.2~3 mL; The molar ratio of cerium in the cerium source to the volume of water is 2~20 mmol: 5~20 mL; The weight of the precious metal element in the precious metal source is 0.05% to 1% of the weight of cerium in the cerium source; The first preset time is 5~15 hours; The second preset time is 2~8 hours.

5. The method for preparing the catalyst for VOCs catalytic combustion as described in claim 1, characterized in that, The molar ratio of the cerium source to the ligand is 1:2; The molar ratio of cerium in the cerium source to the volume of ethylene glycol is 5 mmol: 1 mL; The molar amount of cerium in the cerium source is in the ratio of the volume of water to 5 mmol: 10 mL. The weight of the precious metal element in the precious metal source is 0.4% to 0.8% of the weight of cerium in the cerium source; The first preset time is 12 hours; The second preset time is 4 hours.

6. The method for preparing the catalyst for VOCs catalytic combustion according to any one of claims 1 to 5, characterized in that, In step (1), the cerium source, the noble metal source, the complexing agent, the additive, the water and the ethylene glycol are mixed evenly; The additive is selected from one or more of sodium borohydride, potassium borohydride, and lithium borohydride; The molar ratio of cerium in the cerium source to the molar ratio of the additive is 2~20:0.1~2.

7. The method for preparing the catalyst for VOCs catalytic combustion as described in claim 6, characterized in that, The additive used is sodium borohydride; The molar ratio of cerium in the cerium source to the molar ratio of the additive is 5:0.2~0.

5.

8. The method for preparing the catalyst for VOCs catalytic combustion as described in claim 1, characterized in that, The precious metal source is selected from platinum and palladium sources. The platinum source is selected from platinum nitrate and the palladium source is selected from palladium acetate. The weight ratio of platinum in the platinum source to palladium in the palladium source is 1:0.8~1.

5.

9. The method for preparing the catalyst for VOCs catalytic combustion as described in claim 1, characterized in that, The precious metal source is selected from platinum and ruthenium sources. The platinum source is selected from platinum nitrate and the ruthenium source is selected from ruthenium chloride. The weight ratio of platinum in the platinum source to the weight of ruthenium in the ruthenium source is 1:0.8~1.

5.

10. A catalyst for the catalytic combustion of VOCs, characterized in that, It is prepared by the method for preparing a catalyst for catalytic combustion of VOCs as described in any one of claims 1 to 8.

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