High-performance two-dimensional platinum-cerium cluster catalyst as well as preparation method and application thereof
Synthesizing high-performance two-dimensional platinum cerium cluster catalysts by solution combustion method solves the problems of low efficiency and high cost of existing catalysts at low temperatures, and achieves efficient selective catalytic reduction of ammonia and excellent water resistance.
Patent Information
- Application Number
- CN202411627714.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-14
- Publication Date
- 2025-02-21
AI Technical Summary
The existing ammonia slip catalysts have low efficiency in selective catalytic reduction of nitrogen oxides at low temperatures, and are costly and have poor water resistance.
The solution combustion method is used to synthesize high-performance two-dimensional platinum cerium cluster catalysts. By adjusting the molar ratio of the precursor and the amount of combustion aid, the efficient distribution of platinum load on the CeO2 carrier is achieved, forming a flat cluster structure.
The thermal stability and catalytic performance of the catalyst are improved, the low-temperature activation and selective catalytic reduction efficiency of ammonia are enhanced, and the water resistance is excellent.
Smart Images
Figure CN119488904A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of catalysts, and in particular relates to a high-performance two-dimensional platinum-cerium cluster catalyst and a preparation method and application thereof. Background Art
[0002] Ammonia (NH3) is a significant air pollutant that poses a threat to human health, including damage to the eyes, skin, and respiratory system. It also promotes the formation of secondary inorganic aerosols, leading to environmental issues such as eutrophication and particulate matter formation. NH3 plays an important role as a reducing agent in the selective catalytic reduction (SCR) of nitrogen oxides (NOx) in fixed flue gas denitrification systems and diesel engine exhaust. The ammonia slip catalyst (ASC) is located at the end of the SCR reactor and catalytically removes excess NH3, thereby mitigating these environmental impacts. Since the ASC is usually located in an area with lower exhaust temperature, the development of efficient NH3 oxidation catalysts to selectively convert NH3 into nitrogen (N2) and water (H2O) at low temperatures is key to reducing harmful emissions and improving air quality.
[0003] Ceria (CeO2) is widely used in environmental catalysis due to its unique properties. It is well-known for its excellent redox performance and strong interaction with platinum group metals (PGMs), especially platinum (Pt). These catalysts are of great significance for controlling the cost of precious metals. However, there are some shortcomings in the current commercial industrial catalysts, such as: (1) the use of precious metals is high and the cost is high; (2) the ignition temperature is high and a certain ignition temperature must be reached to achieve the best catalytic performance; (3) the water resistance is poor, and the selectivity of NH3 selective oxidation is low.
[0004] Therefore, it is urgent to develop an efficient, low-cost, and environmentally friendly ASC catalyst. Summary of the invention
[0005] The first purpose of the present invention is to propose a method for preparing a high-performance two-dimensional platinum-cerium cluster catalyst, which greatly simplifies the complicated process of traditional catalysts, has simple preparation steps, and can achieve large-scale mass production.
[0006] The second object of the present invention is to provide a high-performance two-dimensional platinum-cerium cluster catalyst having high thermal stability and excellent catalytic performance.
[0007] The third purpose of the present invention is to propose a high-performance two-dimensional platinum-cerium cluster catalyst for use in ASC, which exhibits excellent catalytic performance.
[0008] In order to solve the above problems, the technical solution adopted by the present invention is as follows:
[0009] A method for preparing a high-performance two-dimensional platinum-cerium cluster catalyst, using (NH4)2Ce(NO3)6 and Pt(NO3)2 as precursors and dihydrazine oxalate as a combustion aid, and loading Pt on a CeO2 carrier through a solution combustion method to obtain a FC-Pt / CeO2 catalyst.
[0010] Furthermore, the molar ratio of (NH4)2Ce(NO3)6 and Pt(NO3)2 is 97-99:1-3.
[0011] Furthermore, the dosage of dihydrazine oxalate is 0.1 mol.
[0012] Furthermore, the solution combustion method requires a temperature of 400° C. and a time of 10 minutes.
[0013] Furthermore, the preparation method of any of the above-mentioned high-performance two-dimensional platinum-cerium cluster catalysts comprises the following steps:
[0014] First, (NH4)2Ce(NO3)6 and Pt(NO3)2 were dissolved in 200 mL of deionized water at a molar ratio of 99:1 to obtain a solution; then, 0.1 mol of dihydrazine oxalate was added to the solution under vigorous stirring at 400 rpm to obtain a mixture; the mixture was then transferred to a corundum crucible, and the corundum crucible containing the mixture was placed in a muffle furnace preheated to 400°C for combustion. After the combustion was completed, the corundum crucible containing the mixture was cooled to room temperature to obtain a solid, and after grinding into 800 mesh powder, the FC-Pt / CeO2 catalyst was obtained.
[0015] Furthermore, the mixture is burned in the muffle furnace for 10 minutes.
[0016] Furthermore, the time for cooling the corundum crucible containing the mixture to room temperature does not exceed 20 minutes.
[0017] Furthermore, a high-performance two-dimensional platinum-cerium cluster catalyst is prepared by any of the above methods.
[0018] Furthermore, the loading amount of platinum in the high-performance two-dimensional platinum-cerium cluster catalyst is 1 at%.
[0019] Furthermore, the high performance two-dimensional platinum-cerium cluster catalyst is used in ASC.
[0020] Compared with the prior art, the advantages of the present invention are as follows:
[0021] 1) The novel Pt-CeO2 catalyst synthesized by the solution combustion method of the present invention has a unique flat cluster (FC) structure. Different from the traditional bulk cluster (BC) catalyst, the FC structure provides a wider reaction interface, promotes the desorption of NH3 and its products, and greatly improves the NH3 oxidation activity of Pt on CeO2.
[0022] 2) The catalyst prepared by the present invention not only optimizes the low-temperature activation of NH3, but also effectively converts the generated nitrous oxide (N2O) into nitric oxide (NO), thereby participating in the enhanced selective catalytic reduction process to generate N2, thereby improving the overall NH3 oxidation efficiency. At the same time, compared with existing commercial catalysts, it has excellent water resistance.
[0023] 3) The method for preparing high-performance two-dimensional platinum-cerium cluster catalysts of the present invention is simple and fast and can be realized in large-scale production. BRIEF DESCRIPTION OF THE DRAWINGS
[0024] Figure 1 This is the XRD result of the support of high-performance two-dimensional platinum-cerium cluster catalyst.
[0025] Figure 2 This is the result of the NH3 oxidation reaction of the high-performance two-dimensional platinum-cerium cluster catalyst.
[0026] Figure 3 AC-STEM-HAADF image of high-performance two-dimensional platinum-cerium cluster catalyst.
[0027] Figure 4 This is the XAS characterization result of the high-performance two-dimensional platinum-cerium cluster catalyst. DETAILED DESCRIPTION
[0028] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with specific embodiments.
[0029] Example 1
[0030] A method for preparing a high-performance two-dimensional platinum-cerium cluster catalyst, comprising the following steps:
[0031] First, (NH4)2Ce(NO3)6 and Pt(NO3)2 were dissolved in 200 mL of deionized water at a molar ratio of 99:1 to obtain a solution; then, dihydrazine oxalate (the dosage of dihydrazine oxalate was 0.1 mol) was added to the solution under vigorous stirring (400 rpm) to obtain a mixture; then, the mixture was transferred to a corundum crucible, and the corundum crucible containing the mixture was placed in a muffle furnace preheated to 400°C. After vigorous burning for 10 minutes, the crucible was allowed to cool to room temperature within 20 minutes to obtain a solid. After grinding into 800 mesh powder, a FC-Pt / CeO2 catalyst with a platinum loading of 1at% was obtained.
[0032] The FC-Pt / CeO2 catalyst well maintains the cubic fluorite structure of CeO2. The corresponding XRD results are as follows: Figure 1 As shown. Figure 1 It can be seen that the crystal structure of the catalyst has not changed and is still a cubic fluorite structure.
[0033] The prepared high-performance two-dimensional platinum-cerium cluster catalyst was characterized by X-ray diffraction (XRD), spherical aberration corrected transmission electron microscopy (AC-STEM), X-ray absorption spectroscopy, X-ray fine structure spectroscopy (XAS) and catalytic performance test (NH3 selective catalytic oxidation reaction) to evaluate its bulk structure, surface structure, reduction properties and catalytic performance. The results are shown in Figure 1-4 . XRD results show that the CeO2 mentioned in the present invention is a cubic fluorite crystal, and the crystal structure does not change before and after loading Pt. Electron microscopy characterization proves that the surface-loaded Pt active species also show obvious structural differences, which are mainly reflected in: Electron microscopy results show that the Pt clusters on the FC-Pt / CeO2 surface are planned to present a two-dimensional morphology of lying down. Compared with conventional three-dimensional cluster catalysts, the contact surface is larger, which represents better catalytic performance. XAS test results show that the FC structure has more Pt-O interface sites than the ordinary BC structure, which is mainly related to the valence state of its carrier surface, strong interaction and excellent reduction performance.
[0034] Example 2
[0035] The same as Example 1, the only difference is that the amount of Pt(NO3)2 added is such that the loading amount of Pt nanoparticles in the cerium oxide-supported platinum catalyst is 2at%, thereby obtaining a Pt(2at%) / CeO2 catalyst.
[0036] A method for preparing a high-performance two-dimensional platinum-cerium cluster catalyst, comprising the following steps:
[0037] First, (NH4)2Ce(NO3)6 and Pt(NO3)2 were dissolved in 200 mL of deionized water at a molar ratio of 98:2 to obtain a solution; then, dihydrazine oxalate (the dosage of dihydrazine oxalate was 0.1 mol) was added to the solution under vigorous stirring (400 rpm) to obtain a mixture; then, the mixture was transferred to a corundum crucible, and the corundum crucible containing the mixture was placed in a muffle furnace preheated to 400°C. After vigorous combustion for 10 minutes, the crucible was allowed to cool to room temperature within 20 minutes to obtain a solid. After grinding into 800 mesh powder, a FC-Pt / CeO2 catalyst with a platinum loading of 2at% was obtained.
[0038] Example 3
[0039] The same as Example 1, the only difference is that the amount of Pt(NO3)2 added is such that the loading amount of Pt nanoparticles in the cerium oxide-supported platinum catalyst is 3at%, thereby obtaining a Pt(3at%) / CeO2 catalyst.
[0040] A method for preparing a high-performance two-dimensional platinum-cerium cluster catalyst, comprising the following steps:
[0041] First, (NH4)2Ce(NO3)6 and Pt(NO3)2 were dissolved in 200 mL of deionized water at a molar ratio of 97:3 to obtain a solution; then, dihydrazine oxalate (the dosage of dihydrazine oxalate was 0.1 mol) was added to the solution under vigorous stirring (400 rpm) to obtain a mixture; then, the mixture was transferred to a corundum crucible, and the corundum crucible containing the mixture was placed in a muffle furnace preheated to 400°C. After vigorous burning for 10 minutes, the crucible was allowed to cool to room temperature within 20 minutes to obtain a solid. After grinding into 800 mesh powder, a FC-Pt / CeO2 catalyst with a platinum loading of 3at% was obtained.
[0042] The cluster catalysts prepared in Examples 1 to 3 all present a two-dimensional flat state, in sharp contrast to the traditional three-dimensional cluster catalysts.
[0043] Example 4
[0044] The high-performance two-dimensional platinum-cerium cluster catalyst prepared in Example 1 of the present invention was applied to the selective catalytic oxidation reaction of NH3 and showed good catalytic performance. Figure 2 . In this experiment, the samples were purged with 50 mL / min of Ar gas at 200°C for 40 min before the activity test. The activity test used a fixed bed reactor, and the tail gas was quantified by an infrared spectrometer (Thermo IS10) equipped with an MCT detector. The raw gas introduced was 500 ppm NH3, 5% O2, with Ar as the balance, and the flow rate was 100 mL / min. 60 mg of catalyst was used.
[0045] The calculation method of NH3 conversion rate is:
[0046]
[0047] Depend on Figure 2 It can be seen that the catalyst of the two-dimensional cluster has better catalytic performance and has the best catalytic performance compared with the traditional three-dimensional cluster PtCe catalyst. Compared with the traditional commercial Pt / Al catalyst, it has better N2 selectivity and water resistance.
[0048] Comparative Example 1
[0049] The synthesis method "solution combustion method" in Example 1 was replaced by "wet impregnation method", and the proportions of other elements were the same as in Example 1. It was found that during the preparation of the catalyst, the surface of the catalyst prepared by the wet impregnation method showed a three-dimensional cluster state ( Figure 3 b) The prepared catalyst was tested for its performance in catalyzing NH3 oxidation. The results showed that the catalytic efficiency at 180°C was only 32%.
[0050] Comparative Example 2
[0051] The combustion agent "oxalyl dihydrazide" in Example 1 was replaced by "ethanol", and the rest was the same as Example 1. The prepared catalyst had an uneven morphology and structure.
[0052] Comparative Example 3
[0053] The combustion temperature "400° C." in Example 1 was replaced by "250° C.", and the rest was the same as Example 1. The prepared catalyst had a large amount of unburned carbon residue attached to its surface.
[0054] Comparative Example 4
[0055] The carrier "CeO2" in Comparative Example 1 was replaced by "Al2O3", and the rest was the same as Example 1. The commercial catalyst currently widely used was prepared, and the low-temperature performance of the catalyst was similar to that of Example 1, but the selectivity was greatly different, and the water resistance was significantly reduced.
[0056] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.
Claims
1. A method for preparing a high-performance two-dimensional platinum-cerium cluster catalyst, characterized in that: Using (NH4)2Ce(NO3)6 and Pt(NO3)2 as precursors and dihydrazine oxalate as a combustion aid, Pt was loaded on the CeO2 carrier through a solution combustion method to obtain the FC-Pt / CeO2 catalyst.
2. The method for preparing a high-performance two-dimensional platinum-cerium cluster catalyst according to claim 1, characterized in that: The molar ratio of (NH4)2Ce(NO3)6 and Pt(NO3)2 is 97-99:1-3.
3. The method for preparing a high-performance two-dimensional platinum-cerium cluster catalyst according to claim 1, characterized in that: The dosage of the dihydrazine oxalate is 0.1 mol.
4. The method for preparing a high-performance two-dimensional platinum-cerium cluster catalyst according to claim 1, characterized in that: The solution combustion method requires a temperature of 400° C. and a time of 10 minutes.
5. The method for preparing a high-performance two-dimensional platinum-cerium cluster catalyst according to any one of claims 1 to 4, characterized in that: Here are the steps: First, (NH4)2Ce(NO3)6 and Pt(NO3)2 were dissolved in 200 mL of deionized water at a molar ratio of 99:1 to obtain a solution; then, 0.1 mol of dihydrazine oxalate was added to the solution under vigorous stirring at 400 rpm to obtain a mixture; the mixture was then transferred to a corundum crucible, and the corundum crucible containing the mixture was placed in a muffle furnace preheated to 400°C for combustion. After the combustion was completed, the corundum crucible containing the mixture was cooled to room temperature to obtain a solid, and after grinding into 800 mesh powder, the FC-Pt / CeO2 catalyst was obtained.
6. The method for preparing a high-performance two-dimensional platinum-cerium cluster catalyst according to claim 5, characterized in that: The mixture was burned in the muffle furnace for 10 min.
7. The method for preparing a high-performance two-dimensional platinum-cerium cluster catalyst according to claim 5, characterized in that: The time for cooling the corundum crucible containing the mixture to room temperature does not exceed 20 minutes.
8. A high-performance two-dimensional platinum-cerium cluster catalyst prepared by the method as described in any one of claims 1 to 7.
9. The high-performance two-dimensional platinum-cerium cluster catalyst according to claim 8, characterized in that: The loading amount of platinum was 1 at%.
10. The application of the high-performance two-dimensional platinum-cerium cluster catalyst in ASC according to claim 9.