Preparation method of high-dispersed pt-based catalyst and application of high-dispersed pt-based catalyst in removal of vocs

Abstract

This invention provides a method for preparing a highly dispersed Pt-based catalyst and its application in VOCs removal, belonging to the field of catalyst technology. The catalyst preparation method includes the following steps: dissolving copper salt and tin salt in dilute nitric acid solution to obtain solution A; adding an aqueous solution of chloroplatinic acid to solution A under stirring to obtain solution B; mixing solution B with titanium oxide uniformly, then drying and calcining to obtain solid A; reducing solid A under a hydrogen atmosphere to obtain the highly dispersed Pt-based catalyst. The Pt loading of the catalyst of this invention is as low as 0.01~0.04 wt% of titanium dioxide, which is an order of magnitude lower than that of ordinary platinum-based catalysts, and both exhibit excellent catalytic activity and stability. The catalyst provided by this invention has 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 highly dispersed Pt-based catalyst and its application in VOCs removal. Background Technology

[0002] Catalytic degradation of volatile organic compounds (VOCs) is a core technology for air pollution control. Platinum-based catalysts, due to their high activity, have become the mainstream materials in this field. However, precious metal resources are scarce and expensive, and improving their atom utilization rate is key to reducing the cost of VOCs treatment. Existing methods for improving the utilization rate of precious metals have significant drawbacks: controlling the positioning of nanoparticles easily leads to the waste of atoms within the particles; single-atom catalysts relying on strong metal-support interactions are prone to metal oxidation, resulting in non-uniform active sites and easy agglomeration at high temperatures. Pt-based catalysts used in industrial VOCs catalysis require maintaining a high loading to offset the activity loss caused by agglomeration and sintering. A large number of Pt atoms are embedded inside the particles and not utilized, resulting in low atom efficiency. Furthermore, the active sites of traditional catalysts are prone to structural reconstruction, leading to poor stability and increased operation and maintenance costs. Therefore, developing precious metal-based VOCs catalytic degradation catalysts with low loading, high atom utilization rate, and high stability is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0003] In view of this, the purpose of this invention is to provide a method for preparing a highly dispersed Pt-based catalyst and its application in VOCs removal.

[0004] To achieve the above objectives, the present invention provides the following technical solution: One of the technical solutions of this invention is a method for preparing a highly dispersed Pt-based catalyst, comprising the following steps: (1) Dissolve copper salt and tin salt in dilute nitric acid solution to obtain solution A; (2) Under stirring conditions, add an aqueous solution of chloroplatinic acid to solution A to obtain solution B; (3) Mix the solution B with titanium oxide until homogeneous, then dry and calcine to obtain solid A; (4) The solid A is reduced under a hydrogen atmosphere to obtain the highly dispersed Pt-based catalyst.

[0005] The second technical solution of the present invention is a highly dispersed Pt-based catalyst prepared by the above preparation method.

[0006] The third technical solution of the present invention is the application of the above-mentioned highly dispersed Pt-based catalyst in the catalytic oxidation of chlorobenzene.

[0007] The present invention discloses the following technical effects: This invention utilizes TiO2 as a support, loading platinum and copper, and introducing tin to prepare a PtSnCu trimetallic single-atom alloy catalyst via high-hydrogen reduction. Taking advantage of the larger atomic radius of Sn atoms compared to Cu, Sn atoms segregate to the surface of Cu nanoparticles. Simultaneously, leveraging the strong interaction between Pt and Sn, Pt single atoms embedded within the Cu lattice are extracted to the surface, achieving nearly 100% surface exposure of Pt atoms, with Pt existing stably in a metallic state. The Pt loading of this catalyst is as low as 0.01~0.04 wt% of titanium dioxide, an order of magnitude lower than that of ordinary platinum-based catalysts, while exhibiting excellent catalytic activity and stability. This provides a new method for the atomic-level efficient utilization of noble metal catalysts.

[0008] The catalyst provided by this invention has excellent low-temperature catalytic oxidation activity and stability of chlorobenzene. Attached Figure Description

[0009] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0010] Figure 1 The XRD patterns are of the catalysts obtained in Examples 1-3 and Comparative Example 1 of this invention. Figure 2 The conversion rates of chlorobenzene (CB) catalytic oxidation by the catalysts obtained in Examples 1-3 and Comparative Example 1 of this invention at different temperatures are shown. Figure 3 The stability curves of the catalysts obtained in Examples 1-3 and Comparative Example 1 of this invention are shown. Figure 4 The carbon dioxide yield of the catalysts obtained in Examples 1-3 and Comparative Example 1 of this invention at different temperatures. Detailed Implementation

[0011] 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.

[0012] 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. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, is also included within the scope of this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0013] 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.

[0014] 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 apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0015] 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.

[0016] Chlorinated volatile organic compounds (Cl-VOCs) are a class of typical air pollutants with high toxicity and poor degradation characteristics, 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, precious metal catalysts suffer from problems such as high cost, easy agglomeration, and weak resistance to chlorine poisoning. Therefore, this invention provides a preparation process for a highly efficient functional catalyst for degrading chlorobenzene that solves the agglomeration problem.

[0017] The first aspect of this invention provides a method for preparing a highly dispersed Pt-based catalyst, comprising the following steps: (1) Dissolve copper salt and tin salt in dilute nitric acid solution to obtain solution A; (2) Under stirring conditions, add an aqueous solution of chloroplatinic acid to solution A to obtain solution B; (3) Mix the solution B with titanium oxide until homogeneous, then dry and calcine to obtain solid A; (4) The solid A is reduced under a hydrogen atmosphere to obtain the highly dispersed Pt-based catalyst.

[0018] In a preferred embodiment of the present invention, the copper salt is copper nitrate trihydrate; the tin salt is tin chloride dihydrate; and the concentration of the dilute nitric acid solution is 2 mol / L.

[0019] More preferably, the ratio of copper salt, tin salt and dilute nitric acid solution is 0.3-0.5g:10-13mg:5mL.

[0020] In a preferred embodiment of the present invention, the concentration of the copper salt and chloroplatinic acid aqueous solution is 1 mg / mL; the ratio of the amount of copper salt and chloroplatinic acid aqueous solution used is 0.369 g: (0.1-1.1) mL.

[0021] More preferably, the concentration of the copper salt and chloroplatinic acid aqueous solution is 1 mg / mL; the ratio of the amount of copper salt and chloroplatinic acid aqueous solution is 0.369 g: 0.265 mL, 0.369 g: 0.531 mL, 0.369 g: 0.796 mL or 0.369 g: 1.06 mL.

[0022] In a preferred embodiment of the present invention, the titanium oxide is titanium dioxide; the mass ratio of the copper salt to titanium dioxide is 0.3-0.5:1.

[0023] In a preferred embodiment of the present invention, the drying temperature is 60℃-70℃ and the drying time is 8-14h.

[0024] In a preferred embodiment of the present invention, the calcination temperature in step (3) is 400-600℃, the time is 1-3h, and the heating rate is 3-6℃ / min.

[0025] More preferably, the calcination temperature in step (3) is 400℃, 450℃, 500℃, 550℃ or 600℃, the time is 1h, 1.5h, 2h, 2.5h or 3h, and the heating rate is 3℃ / min, 4℃ / min, 5℃ / min or 6℃ / min.

[0026] In a preferred embodiment of the present invention, the reduction temperature in step (4) is 300-500°C, the time is 0.5-1.5h, and the hydrogen concentration is 8%-11% (v / v).

[0027] More preferably, the reduction temperature in step (4) is 300°C, 350°C, 400°C, 450°C or 500°C, the time is 0.5h, 1h or 1.5h, and the hydrogen concentration is 8%, 9%, 10% or 11% (v / v).

[0028] A second aspect of the present invention provides a highly dispersed Pt-based catalyst prepared by the above-described preparation method.

[0029] A third aspect of the present invention provides the application of the above-mentioned highly dispersed Pt-based catalyst in the catalytic oxidation of chlorobenzene.

[0030] In a preferred embodiment of the present invention, the highly dispersed Pt-based catalyst is used in the catalytic oxidation of chlorobenzene at a reaction temperature of 275-400°C, more preferably 340-400°C.

[0031] This invention employs a simple and low-cost preparation method. Based on the strong interaction between Pt and Sn, Pt single atoms embedded in the Cu lattice are extracted to the surface, achieving nearly 100% surface exposure of Pt atoms, thus forming a highly efficient Cl-VOCs catalyst. This catalyst exhibits high efficiency at 30000 mL·g⁻¹. -1 ·h -1 At a space velocity of 500 ppm chlorobenzene, a 90% conversion rate was achieved at 340℃ and a 50% conversion rate was achieved at 275℃, demonstrating excellent catalytic oxidation performance of chlorobenzene.

[0032] In this invention, uniform mixing is achieved by stirring for 20-40 minutes. The stirring speed has no particular effect on the performance of the catalyst; therefore, this invention does not impose specific limitations on the stirring speed and adopts stirring speeds commonly used by those skilled in the art. The purpose of stirring, in addition to achieving uniform mixing, is to accelerate dissolution.

[0033] Unless otherwise specified, the technical solutions described in this invention are all conventional solutions in the field, and the reagents or raw materials used are all purchased from commercial channels or are publicly available unless otherwise specified.

[0034] To better understand the present invention, the following embodiments further illustrate the content of the present invention, but the content of the present invention is not limited to the following embodiments.

[0035] In the examples, the formula for calculating the Pt loading in the catalyst is: loading = Pt mass / TiO2 mass × 100%.

[0036] Example 1 (1) Dissolve 0.369g of copper nitrate trihydrate in 5mL of 2mol / L dilute nitric acid, and then add 11.6mg of tin dichloride dihydrate to obtain solution A; (2) Under stirring conditions, 0.796 mL of 1 mg / mL chloroplatinic acid hexahydrate solution was added to solution A to obtain solution B; (3) Add the solution B obtained in step (2) dropwise to 1g of titanium dioxide, stir until uniformly moistened, then put it in an oven at 60℃ and dry for 12h, then put it in a muffle furnace at 500℃ for 2h (heating rate is 3℃ / min) to obtain solid A; (4) Solid A was calcined at 500°C for 1.5 h in a hydrogen environment (hydrogen concentration of 11% (v / v)) to obtain a highly dispersed Pt-based catalyst.

[0037] The Pt loading in this highly dispersed Pt-based catalyst is 0.03 wt%.

[0038] Example 2 Same as in Example 1, except that 0.796 mL of 1 mg / mL chloroplatinic acid hexahydrate solution was replaced with 0.531 mL of 1 mg / mL chloroplatinic acid hexahydrate solution.

[0039] The Pt loading in this highly dispersed Pt-based catalyst is 0.02 wt%.

[0040] Example 3 Same as in Example 1, except that 0.796 mL of 1 mg / mL chloroplatinic acid hexahydrate solution was replaced with 1.06 mL of 1 mg / mL chloroplatinic acid hexahydrate solution.

[0041] The Pt loading in this highly dispersed Pt-based catalyst is 0.04 wt%.

[0042] Comparative Example 1 (1) Dissolve 0.369 g of copper nitrate trihydrate in 5 mL of 2 mol / L dilute nitric acid to obtain solution A; (2) Under stirring conditions, 0.796 mL of 1 mg / mL chloroplatinic acid hexahydrate solution was added to solution A to obtain solution B; (3) Add the solution B obtained in step (2) dropwise to 1g of titanium dioxide, stir until uniformly moistened, then put it in an oven at 60℃ and dry for 12h, then put it in a muffle furnace at 500℃ for 2h (heating rate is 3℃ / min) to obtain solid A; (4) Solid A was calcined at 500°C for 1.5 h in a hydrogen environment (hydrogen concentration of 11% (v / v)) to obtain the catalyst.

[0043] Figure 1 The XRD patterns of the catalysts prepared in Examples 1-3 and Comparative Example 1 show that TiO2 characteristic peaks are mainly exposed in all samples, indicating that the samples were successfully prepared.

[0044] Effect verification: The catalytic oxidation activity of the catalysts prepared in Examples 1-3 and Comparative Example 1 was tested. The test method was 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 2The figures show the conversion rates of chlorobenzene (CB) oxidized by the catalysts prepared in Examples 1-3 and Comparative Example 1 at different temperatures. As can be seen from Figure 2, the catalysts prepared in this invention exhibit excellent chlorobenzene oxidation capabilities, with the catalyst prepared in Example 1 showing the best performance, achieving a chlorobenzene conversion rate of 90% at 340℃. When the introduction of tin is omitted during catalyst preparation, the catalytic performance of the resulting catalyst decreases significantly.

[0045] Figure 3 The figures show the stability curves of the catalysts prepared in Examples 1-3 and Comparative Example 1 of this invention. As can be seen from the figures, the catalysts prepared in this invention exhibit excellent chlorobenzene oxidation ability and good stability.

[0046] Figure 4 The carbon dioxide yield of the catalysts prepared in Examples 1-3 and Comparative Example 1 of this invention at different temperatures. Figure 4 As can be seen, the catalyst prepared by this invention has a high carbon dioxide yield, indicating that the catalyst has excellent performance in catalytic oxidation of chlorobenzene.

[0047] 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 highly dispersed Pt-based catalyst, characterized in that, Includes the following steps: (1) Dissolve copper salt and tin salt in dilute nitric acid solution to obtain solution A; (2) Under stirring conditions, add an aqueous solution of chloroplatinic acid to solution A to obtain solution B; (3) Mix the solution B with titanium oxide until homogeneous, then dry and calcine to obtain solid A; (4) The solid A is reduced under a hydrogen atmosphere to obtain the highly dispersed Pt-based catalyst.

2. The preparation method according to claim 1, characterized in that, The copper salt is copper nitrate trihydrate; the tin salt is tin chloride dihydrate; and the concentration of the dilute nitric acid solution is 2 mol / L.

3. The preparation method according to claim 2, characterized in that, The ratio of copper salt, tin salt, and dilute nitric acid solution used is 0.3-0.5g:10-13mg:5mL.

4. The preparation method according to claim 1, characterized in that, The concentration of the copper salt and chloroplatinic acid aqueous solution is 1 mg / mL; the ratio of the amount of copper salt and chloroplatinic acid aqueous solution used is 0.369 g: (0.1-1.1) mL.

5. The preparation method according to claim 1, characterized in that, The titanium oxide is titanium dioxide; the mass ratio of the copper salt to titanium dioxide is 0.3-0.5:

1.

6. The preparation method according to claim 1, characterized in that, The drying temperature is 60℃-70℃, and the time is 8-14 hours.

7. The preparation method according to claim 1, characterized in that, The calcination temperature in step (3) is 400-600℃, the time is 1-3h, and the heating rate is 3-6℃ / min.

8. The preparation method according to claim 1, characterized in that, The reduction temperature in step (4) is 300-500℃, the time is 0.5-1.5h, and the hydrogen concentration is 8%-11%.

9. A highly dispersed Pt-based catalyst prepared by the preparation method according to any one of claims 1-8.

10. The application of the highly dispersed Pt-based catalyst of claim 9 in the catalytic oxidation of chlorobenzene.

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