A supported single atom / nanocluster composite noble metal catalyst and its preparation method and application

Abstract

The present invention discloses a supported single-atom / nanocluster composite noble metal catalyst, its preparation method, and application. The preparation of the catalyst comprises: 1) dissolving a noble metal M precursor in water, adding an organic complexing agent, stirring for a complex reaction, adding a carrier to the obtained noble metal M precursor complex solution, stirring thoroughly to load the complex onto the carrier, filtering, drying, and rapidly thermally shocking the solution in a Joule ultrafast heating device in an H2 atmosphere to produce a single-atom catalyst; and 2) loading the noble metal M nanocluster sol onto the single-atom catalyst by a sol impregnation method to produce a catalyst in which single atoms and nanoclusters of the noble metal M coexist. The preparation process of the catalyst of the present invention is simple, requiring only a single-step heat treatment, and can ensure that single atoms / nanoclusters in the catalyst are synthesized in a controlled manner in proportion. The preparation method of the present invention can precisely control the ratio of single atoms to nanoclusters according to the specific reaction, thereby achieving the preparation of a highly active catalyst.

Description

Technical Field

[0001] The invention relates to a supported single atom / nano cluster composite noble metal catalyst and a preparation method and application thereof. Background Art

[0002] Supported noble metal catalysts have been widely studied and applied due to their high activity, selectivity and stability in many reactions. In previous studies, researchers have been committed to highly dispersing noble metals to nanometers (2-10nm), sub-nanometers (<2nm) and even single atoms to improve the effective utilization of metal atoms and the reaction rate per unit active site. In some catalytic reactions, especially when two or more molecules are involved in adsorption and activation, single dispersed active species often cannot meet the requirements of simultaneous adsorption and activation of multiple molecules. Therefore, in recent years, single atom and nanoparticle composite catalysts have begun to receive attention and research. For example, the following literature discloses research content:

[0003] 1) J. Am. Chem. Soc. 2023, 145, 9540 reports a laser ablation strategy for preparing a catalyst containing both single atoms and nanoparticles for CO oxidation. Laser irradiation enables the redispersion of Pt nanoparticles, dispersing some Pt ​​particles into single atoms. This allows for full CO conversion at 250°C in the CO oxidation reaction.

[0004] 2) Reference J.Am.Chem.Soc.2024,146,35,24440 prepared Pd single atoms by ion exchange and Pd nanoclusters by photodeposition method for photocatalytic methanol dehydrogenation reaction.

[0005] 3) In the literature J.Energy Chem.2023,79,535, a dual-sized MOF-derived Co catalyst of single-atom Co and highly dispersed nanoparticle Co was prepared by in situ evaporation method for the cascade demethoxylation and dearomatization of lignin-derived o-methoxyphenol to cyclohexanol.

[0006] However, the methods disclosed in the aforementioned literature present the following technical challenges: the catalyst preparation steps are relatively complex, requiring high equipment requirements and typically requiring two or more heat treatments. The precious metals in the catalysts struggle to maintain structural stability, making it difficult to achieve a controlled dispersion scale. Furthermore, the support is not universally applicable, with some methods being applicable only to oxide supports and others only to carbon supports. Therefore, it is urgent to develop a method for preparing single-atom and nanoparticle composite catalysts that is universally applicable, has a controllable single-atom / nanoparticle ratio, is structurally stable, and undergoes mild, environmentally friendly preparation conditions. Summary of the Invention

[0007] In view of the problems existing in the prior art, the present invention provides a method for preparing a supported single atom / nanocluster composite catalyst, which has the characteristics of universal carrier and controllable single atom / nanocluster ratio. First, single atoms are loaded by ligand complexation coupled thermal shock method, and then nanoclusters are loaded by sol impregnation method. Since H2 is used for thermal shock to obtain a single-atom dispersed catalyst during the preparation process, and nanoclusters are obtained by alcohol-base reduction, secondary heat treatment and reduction steps are avoided, and the single atoms and nanoclusters in the catalyst are synthesized in proportion, and the structure is stable. Another technical problem solved by the present invention is that the single atom / nanocluster composite catalyst obtained by the preparation method of the present invention shows higher oxidation performance than pure single atoms and pure nanoclusters in CO oxidation reaction. Compared with the prior art, the preparation process of the present invention is simple, does not require secondary heat treatment and reduction treatment, is conducive to the synthesis of single atoms and nanoclusters in the catalyst in proportion, and has good carrier universality, and is applicable to both oxide carriers and carbon carriers.

[0008] The catalyst of the present invention is a single-atom / nanocluster composite catalyst, in which the ratio of single atoms in the single-atom / nanocluster can be controlled within a range of 10 to 90%, and the nanocluster particle size is controlled to be 1 to 2 nm. In terms of preparation method, the single-atom catalyst is loaded with single atoms through a coordination complex coupled thermal shock method, while the nanoclusters are loaded through a sol-gel impregnation method.

[0009] The technical solution adopted in the present invention is as follows:

[0010] A method for preparing a supported noble metal catalyst, wherein the active component noble metal in the catalyst coexists in the form of single atoms and nanoclusters, and the single atom / nanocluster ratio is controllable, comprising the following steps:

[0011] 1) dissolving a noble metal M precursor in deionized water, adding an organic complexing agent, and stirring to carry out a complex reaction to obtain a noble metal M precursor complex solution;

[0012] 2) adding a carrier to the solution in step 1), stirring thoroughly to load the complex onto the carrier, filtering, drying, and placing the resulting solid product in a Joule ultrafast heating device in a H2 atmosphere for rapid thermal shock to produce a single-atom catalyst;

[0013] 3) loading the noble metal M nanocluster sol onto the single atom catalyst in step 2) by a sol impregnation method to obtain a catalyst in which single atoms and nanoclusters of the noble metal M coexist;

[0014] wherein the noble metal M is at least one of Pt, Rh, Ir, Ru, and Pd;

[0015] The molar amount of the noble metal M atoms in the catalyst accounts for 10-90% of the total amount of the noble metal M atoms and nanoclusters;

[0016] The loading amount of the noble metal M in the catalyst is 0.1-1%.

[0017] Furthermore, the organic complexing agent in step 1) is at least one of ethylenediamine, sodium ethylenediaminetetraacetate, triethylamine, monoethanolamine, diethylenetriamine, and tetraethylenepentamine, and the molar amount of the organic complexing agent is (5 to 20) × 10 of the molar amount of the noble metal M precursor. 3 times; step 1) stirring the complex reaction temperature is room temperature, the reaction time is 1 to 5h.

[0018] Furthermore, the carrier in step 2) is CeO2, TiO2 or MnO2, FeO x At least one of metal oxides and carbon carriers such as activated carbon and carbon nanotubes, preferably CeO2 or TiO2, and the stirring time in step 2) is 2 to 10 hours.

[0019] Furthermore, the rapid thermal shock in step 2) is achieved by Joule ultrafast heating, where the temperature is rapidly raised to a heat treatment temperature of 500-800° C. within 500 milliseconds, the heat treatment time is 10-600 seconds, and then the temperature is naturally lowered to room temperature.

[0020] Furthermore, the heat treatment temperature is 550-650° C., and the heat treatment time is 20-60 seconds.

[0021] Furthermore, the specific steps of step 3) are: diluting the nanocluster sol of the precious metal M with ethylene glycol, and adding the resulting solution dropwise to the single-atom catalyst while stirring evenly; then immersing at room temperature for 10 to 20 hours, and then drying the sample in a vacuum oven, and drying under vacuum to evaporate the solvent, thereby obtaining a catalyst in which single atoms and nanoclusters of the precious metal M coexist.

[0022] Furthermore, the molar amount of the noble metal M atoms in the catalyst accounts for 10 to 50% of the total amount of the noble metal M atoms and nanoclusters, preferably 10 to 30%.

[0023] Furthermore, the loading amount of the noble metal M in the catalyst is 0.1 to 0.5%.

[0024] The present invention also discloses the use of the supported noble metal catalyst with controllable single atom / nano cluster ratio in catalyzing CO oxidation reaction.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] 1) The present invention uses a coordination complex coupled thermal shock method and sol-gel impregnation method to load single atoms and nanoclusters onto a support, respectively, successfully preparing a catalyst in which single atoms and nanoclusters coexist. This preparation method eliminates the need for secondary heat treatment, which helps maintain the stability of the single-atom and nanocluster structures in the catalyst. Furthermore, the preparation method is easy to control, has mild preparation conditions, has a strong support universality, requires low synthesis equipment, and reduces preparation costs. The catalyst exhibits excellent activity in the CO oxidation reaction.

[0027] 2) The catalyst prepared by the coordination complex coupled thermal shock method-sol impregnation method adopted in the present invention realizes noble metal reduction during the preparation process without the need for other reduction steps, ensuring that the ratio of single atoms and nanoclusters in the catalyst is controllable and the structure is stable.

[0028] 3) The catalyst preparation process is simple, requiring only a single heat treatment step. This ensures the controlled synthesis of single atoms and nanoclusters in the catalyst, with the nanoclusters uniformly distributed in size between 1 and 2 nm. In the CO oxidation reaction, a 4:1 ratio of single atoms to nanoclusters exhibits the highest oxidation performance. This method allows for precise control of the single-atom to nanocluster ratio based on the specific reaction, resulting in the preparation of a highly active catalyst.

[0029] 4) The catalyst of the present invention can achieve complete CO conversion at lower temperatures, which not only reduces energy consumption and improves catalytic reaction safety, but also helps avoid carbon deposition on the catalyst at high temperatures or oxidation and deactivation of platinum species, greatly extending the service life of the catalyst. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 0.02Pt10.08Pt prepared in Example 1 and Comparative Examples 1 and 2 of the present invention NP / CeO2, 0.1Pt1 / CeO2 and 0.1Pt NP / CeO2 catalyst CO oxidation reaction performance test diagram.

[0031] Figure 2 This is a test diagram of the CO oxidation reaction performance of catalysts with different ratios of single atoms and nanoclusters prepared in Example 1 and Examples 2-6 of the present invention.

[0032] Figure 3 0.02X10.08X prepared by different precious metals prepared in Examples 1, 7-10 of the present invention NP CO oxidation reaction performance test diagram of / CeO2 (X is Pt, Rh, Ir, Ru, Pd) catalyst.

[0033] Figure 4 0.02Pt10.08Y prepared in Examples 1, 11-14 of the present inventionNP CO oxidation reaction performance test diagram of / CeO2 (Y is Pt, Rh, Ir, Ru, Pd) catalyst.

[0034] Figure 5 This is a test chart of the CO oxidation reaction performance of catalysts with different Pt loadings prepared in Examples 1, 15, and 16 of the present invention.

[0035] Figure 6 This is a test chart of CO oxidation reaction performance of different supported catalysts prepared in Examples 1, 17, 18, and 19 of the present invention.

[0036] Figure 7 This is a test diagram of the CO oxidation reaction performance of the catalyst prepared in Example 1 and Comparative Example 3 of the present invention.

[0037] Figure 8 This is a test diagram of the CO oxidation reaction performance of the catalysts prepared in Example 1 and Comparative Example 4 of the present invention.

[0038] Figure 9 AC-HAADF-STEM electron micrographs of the catalysts prepared in Example 1(a), Comparative Example 1(b), and Comparative Example 2(c) of the present invention (the red circles represent Pt nanoclusters, and the yellow circles represent Pt single atoms).

[0039] Figure 10 0.02Pt10.08Pt prepared in Example 1 NP / CeO2 catalyst CO oxidation reaction stability performance test diagram. DETAILED DESCRIPTION

[0040] The technical solutions in the embodiments of the present invention will be described clearly and completely below with reference to the accompanying drawings in the embodiments of the present invention.

[0041] Example 1: 0.02Pt10.08Pt NP / CeO2 catalyst preparation:

[0042] (1) Preparation of single-atom Pt1 / CeO2 catalyst by coordination complex coupling thermal shock method: 27 μL of H2PtCl6 aqueous solution with a Pt element concentration of 7.46 mg / mL was measured and added to 50 mL of deionized water for dilution. 1.0 g of ethylenediamine reagent was added and stirred for 3 h. 1.0 g of CeO2 was added and stirred for 5 h. The catalyst precursor was filtered and washed, and placed in a vacuum oven at 80 ° C and dried for 12 h to obtain a catalyst precursor. The catalyst precursor was then placed in a Joule ultrafast heating device and heated under a flowing 30 mL·min -1 In a pure hydrogen atmosphere, the catalyst was heated from room temperature to 600°C within 200 milliseconds, heat treated for 30 seconds, and then naturally cooled to room temperature to obtain a Pt1 / CeO2 catalyst with a Pt single atom load of 0.02 wt%.

[0043] (2) Preparation of precious metal sol by alcohol-base reduction method: Taking Pt sol as an example, Pt sol was prepared by ethylene glycol reduction method. A certain amount of chloroplatinic acid ethylene glycol solution and an appropriate amount of sodium hydroxide ethylene glycol solution were mixed in a three-necked flask, and then reduced in an inert atmosphere at an oil bath temperature of 160°C to obtain Pt sol: Specifically, 1g H2PtCl6·6H2O was dissolved in 50mL ethylene glycol, and 50mL of 0.25mol L -1 The sodium hydroxide ethylene glycol solution was stirred at room temperature for 1 hour and then transferred to a 160°C oil bath. The mixture was stirred under argon atmosphere for 1 hour to obtain a dark brown transparent Pt sol (Pt mass concentration 3.76 mg mL -1 ).

[0044] (3) Sol impregnation method for loading nanoclusters: Weigh 1 g of single-atom Pt1 / CeO2 catalyst dried in a 120°C oven for 2 h in a 20 mL beaker, measure 213 μL of Pt sol with a Pt element concentration of 3.76 mg / mL, add 2 mL of ethylene glycol to dilute it, and then add it dropwise to the Pt1 / CeO2 catalyst while stirring evenly; then impregnate it at room temperature for 12 h, and then dry the sample in a vacuum oven at 120°C for 12 h to obtain a catalyst 0.02Pt10.08Pt in which single-atom Pt and nanoclusters Pt coexist. NP / CeO2, the total Pt loading of the catalyst is 0.1wt%.

[0045] Example 2-6:

[0046] The preparation method of the catalyst of Example 2-6 is the same as that of Example 1, with the only difference being that the added volume of the H2PtCl6 aqueous solution in step (1) and the added volume of the Pt sol in step (3) are changed, while the other conditions remain unchanged. This allows the total Pt loading of the catalyst of Example 2-6 to remain unchanged at 0.1 wt%, while the ratio of Pt single atoms and nanoclusters changes.

[0047] The specific volumes of H2PtCl6 aqueous solution and Pt sol added during the catalyst preparation process of Examples 2-6, as well as the ratios of Pt single atoms and nanoclusters in the catalysts, are shown in Table 1.

[0048] Table 1

[0049]

[0050] Examples 7-10:

[0051] The preparation methods of the catalysts of Examples 7-10 were the same as those of Example 1, differing only in the type of precious metal. The mass of the precious metal element in steps (1), (2), and (3) remained unchanged, and all other conditions remained unchanged. The total precious metal loading of the catalysts of Examples 7-10 remained unchanged at 0.1 wt%, and the ratio of single noble metal atoms to nanoclusters remained unchanged.

[0052] The types of noble metals, single atom precursors, and nanoclusters used in the catalyst preparation processes of Examples 7-10 are shown in Table 2.

[0053] Table 2

[0054]

[0055] Examples 11-14: The catalyst preparation process was the same as in Example 1, differing only in the type of precious metal nanoclusters used in the catalyst preparation. The mass of the precious metal elements in steps (2) and (3) remained unchanged, and all other conditions remained unchanged. The total precious metal loading of the catalysts in Examples 11-14 remained unchanged at 0.1 wt%, and the ratio of single precious metal atoms to nanoclusters remained unchanged. The specific conditions for varying the type of precious metal nanoclusters are shown in Table 3.

[0056] Table 3

[0057]

[0058]

[0059] Examples 15-16: The catalyst preparation method was the same as that of Example 1, except that the volume of the H₂PtCl₆ aqueous solution added in step (1) and the volume of the Pt sol added in step (3) were changed. All other conditions remained unchanged, resulting in a change in the total Pt loading of the catalyst. Specific condition changes are shown in Table 4.

[0060] Table 4

[0061]

[0062] Examples 17-19: The catalyst preparation method is the same as that of Example 1, except that the catalyst support is different. Other conditions remain unchanged. Specific changes in the catalyst support are shown in Table 5.

[0063] Table 5

[0064]

[0065] Comparative Example 1: A single-atom dispersed 0.1Pt1 / CeO2 catalyst was prepared by a coordination complex coupled thermal shock method, wherein the Pt loading was 0.1wt%. The specific steps were as follows: 134μL of an H2PtCl6 aqueous solution with a Pt element mass concentration of 7.46mg / mL was taken as a Pt source, added to 50mL of deionized water for dilution, 1.0g of ethylenediamine reagent was added, stirred for 3h, and then 1.0g of CeO2 was added, stirred for 5h, filtered and washed, placed in a vacuum oven at 80℃, dried for 12h to obtain a catalyst precursor, and then placed the precursor in a Joule ultrafast heating device under a flowing 30mL min -1 In a pure hydrogen atmosphere, the catalyst was heated from room temperature to 600°C within 200 milliseconds, heat treated for 30 seconds, and then naturally cooled to room temperature to obtain a 0.1Pt1 / CeO2 catalyst with a Pt single atom load of 0.1wt%.

[0066] Comparative Example 2: Preparation of 0.1Pt by sol impregnation method NP / CeO2 catalyst, wherein the Pt loading amount is 0.1wt%, and the specific steps are as follows: weigh 1g of CeO2 dried in a 120℃ oven for 2h and put it into a 20mL beaker, measure 266μL of Pt sol with a Pt element concentration of 3.76mg / mL (for the preparation of Pt sol, see step (2) of Example 1), add 2mL of ethylene glycol to dilute it, and then add it dropwise to CeO2 while stirring evenly; then immerse it at room temperature for 12h, and then dry the sample in a vacuum oven at 120℃ for 12h to obtain 0.1Pt NP / CeO2 catalyst.

[0067] Comparative Example 3: The preparation process is the same as that of Example 1. Compared with Example 1, the difference is that the Pt single atom load is prepared by a tube furnace heating method. The specific steps are: 27 μL of H2PtCl6 aqueous solution with a Pt element concentration of 7.46 mg / mL is measured as a Pt source, added to 50 mL of deionized water for dilution, 1.0 g of ethylenediamine reagent is added, stirred for 3 h, and then 1.0 g of CeO2 is added, stirred for 5 h, filtered and washed, placed in a vacuum oven at 80 ° C, and dried for 12 h to obtain a catalyst precursor, which is placed in a tube furnace and slurried in a flowing 30 mL min -1 In H2 atmosphere, the temperature was raised from room temperature to 600℃ at a rate of 10℃ / min. After 30s of heat treatment, the heating was terminated and the mixture was naturally cooled to room temperature. The subsequent steps were consistent with the steps (2)-(3) of Example 1 to obtain 0.02Pt10.08Pt NP / CeO2-Tube catalyst.

[0068] Comparative Example 4: The specific preparation method of the catalyst is the same as that of Example 1, except that "ethylenediamine reagent is not added in step (1)", and the other conditions remain unchanged. The final catalyst is marked as 0.02Pt10.08Pt NP / CeO2-without complexing agent, in which the Pt loading amount is 0.1wt%.

[0069] Application examples:

[0070] In order to evaluate the catalytic performance of the prepared catalyst, the CO oxidation reaction performance test was carried out. A fixed bed reactor was used, 60-100 mg of catalyst was weighed and loaded into a U-shaped reaction tube, and the flow rate was 30 mL min -1 The reaction gas composition is 1 vol% CO + 1 vol% O2, Ar is the balance gas, and the mass space velocity is 1.8×10 4 ~3.0×10 4 mL·g cat -1 h -1 , record the peak areas of CO, O2, and CO2 at the outlet of the chromatographic detection reactor. The CO conversion rate is calculated as follows:

[0071] CO Conversion (%) = ([CO] in -[CO] out ) / [CO] in ×100%;

[0072] Where: [CO] in is the chromatographic peak area corresponding to CO at the reactor inlet;

[0073] [CO] out is the chromatographic peak area corresponding to CO at the reactor outlet at different reaction temperatures.

[0074] The CO oxidation reaction performance evaluation conditions are: flow rate 30 mL min -1 The gas composition is 1vol% CO + 1vol% O2, Ar is the balance gas, and the mass space velocity is 1.8×10 4 mL·g cat -1 h -1 During the evaluation of CO oxidation reaction performance, the catalyst was subjected to a temperature programmed activity test. The test temperature range was 20-200°C, with a starting temperature of 20°C. Each temperature was maintained for 20 minutes and a sample was taken for analysis. Then, the temperature was adjusted at 2°C min. -1 The temperature is raised to the next temperature evaluation point at a rate of

[0075] The catalyst stability evaluation conditions are: flow rate 30 mL min -1The reaction temperature was 120 °C, the gas composition was 1 vol% CO + 1 vol% O2, Ar was the balance gas, and the mass space velocity was 3.0 × 10 4 mL·g cat -1 h -1 .

[0076] The CO oxidation performance test comparison results of the catalysts of Example 1 of the present invention and Comparative Examples 1 and 2 are shown in Figure 1 , Figure 1 The results show that the CO conversion rate on 0.1Pt1 / CeO2 catalyst is below 50% in the temperature range of 20-200℃, which is low. NP / CeO2 catalyst, the CO conversion rate was only 38.3% at 140℃, and reached 100% at 160℃; 0.02Pt10.08Pt NP / CeO2 catalyst has the best activity, with a CO conversion rate of 29% at 20℃ and full CO conversion at 120℃.

[0077] The CO oxidation reaction performance test comparison results of the catalysts of Example 1 and Examples 2-6 of the present invention are shown in Figure 2 , Figure 2 It shows that when the ratio of single atoms to nanoclusters is 4:1, that is, 0.08Pt10.02Pt NP / CeO2 catalyst, CO full conversion was not achieved in the temperature range of 20-200℃; when the ratio of single atoms to nanoclusters was 7:3, that is, 0.07Pt10.03Pt NP / CeO2 catalyst, CO oxidation activity was improved; when the ratio of single atoms to nanoclusters was 1:1, the CO oxidation activity was improved in the case of 0.05Pt10.05Pt NP / CeO2 catalyst, CO can be completely converted at 200 ° C; further increase the ratio of Pt clusters, that is, when the ratio of single atoms to nanoclusters is 1:4, the conversion rate of 0.02Pt10.08Pt NP / CeO2, the CO full conversion temperature decreased to 120 ° C; when the Pt cluster ratio increased to 90%, that is, when the ratio of single atoms to nanoclusters was 1:9, the CO oxidation activity decreased, and the CO full conversion temperature was 140 ° C; the results show that when the nanocluster ratio was 80% (0.02Pt10.08Pt NP / CeO2), which has the best catalytic oxidation effect and significantly improved CO oxidation performance, indicating that single atoms and nanoclusters have a synergistic effect in the CO oxidation process.

[0078] The CO oxidation reaction performance test comparison results of the catalysts of Examples 1, 7-10 of the present invention are shown in Figure 3 , Figure 3The results show that the single-atom catalyst was prepared by the coordination complex coupled thermal shock method of the present invention, and then the clusters were loaded by the sol impregnation method to obtain a series of catalysts 0.02X10.08X NP / CeO2 (Rh, Pd, Ir, Pt, Ru), in the CO oxidation reaction, the activity order is 0.02Pt10.08Pt NP / CeO2>0.02Rh10.08Rh NP / CeO2>0.02Ir10.08Ir NP / CeO2>0.02Ru10.08Ru NP / CeO2>0.02Pt10.08Pd NP / CeO2, indicating that the Pt-based catalyst has higher CO oxidation performance.

[0079] The CO oxidation performance test comparison results of the catalysts of Examples 1 and 11-14 of the present invention are shown in Figure 4 , Figure 4 The results showed that Y NP (Y is Rh, Pd, Ir, Pt, Ru), the order of CO oxidation catalytic performance is 0.02Pt10.08Pt NP / CeO2>0.02Pt10.08Rh NP / CeO2>0.02Pt10.08Ir NP / CeO2>0.02Pt10.08Ru NP / CeO2>0.02Pt10.08Pd NP / CeO2, indicating that in the CO oxidation reaction, the synergistic effect of single-atom Pt and nanocluster Pt is the best.

[0080] The CO oxidation performance test comparison results of the catalysts of Examples 1, 15 and 16 of the present invention are shown in Figure 5 , Figure 5 The results show that the ratio of single atoms to nanoclusters is kept at 4:1, and the total Pt loading is changed from 0.002Pt to 10.008Pt. NP / CeO2 catalyst, CO conversion was not achieved in the temperature range of 20-200℃. When the total Pt loading was increased to 0.5wt%, that is, 0.1Pt10.4Pt NP / CeO2 catalyst, full CO conversion can be achieved at 40℃.

[0081] The CO oxidation reaction performance test comparison results of the catalysts of Examples 1, 17, 18 and 19 of the present invention are shown in Figure 6 , Figure 6The results show that Pt single atom and nanocluster coexisting catalysts loaded with different carriers (MnO2, TiO2, CNT) were prepared by the method of the present invention, and it was found that all of them had high CO oxidation performance, indicating that the catalyst preparation method of the present invention has universal applicability.

[0082] The CO oxidation reaction performance test comparison results of the catalysts of Example 1 and Comparative Example 3 are shown in Figure 7 . Figure 7 The results show that the 0.02Pt10.08Pt prepared in Example 1 NP / CeO2 catalyst prepared in Comparative Example 3, 0.02Pt10.08Pt NP The catalytic performance of the CeO2-Tube catalyst in the CO oxidation reaction decreased significantly, and CO could only be completely converted at 180°C, which further illustrates the excellent performance of the catalyst prepared by the method of the present invention.

[0083] The CO oxidation reaction performance test comparison results of the catalysts of Example 1 and Comparative Example 4 are shown in Figure 8 . Figure 8 The results show that compared with 0.02Pt10.08Pt in Example 1 NP Compared with the 0.02Pt10.08Pt / CeO2 catalyst without adding complexing agent, NP The catalytic performance of the CeO2-complexing agent-free catalyst in the CO oxidation reaction decreased significantly, and complete CO conversion was not achieved within the tested temperature range. This indicates that the addition of organic complexing ligands helps the formation of Pt single atoms, which synergizes with Pt clusters in the catalyst to promote CO oxidation.

[0084] The AC-HAADF-STEM images of the catalysts of Example 1, Comparative Example 1 and Comparative Example 2 are shown in FIG. Figure 9 Figures a, b and c of . Figure 9 The results show that if Figure 9 As shown in Figure a, at 0.02Pt10.08Pt NP On the / CeO2 catalyst, the dispersion of Pt nanoclusters and Pt single atoms can be observed simultaneously; Figure 9 As shown in Figure b, on the 0.1Pt1 / CeO2 catalyst, Pt is highly dispersed on the support in the form of single atoms, without the appearance of clusters or nanoparticles; Figure 9 As shown in Figure c, at 0.1Pt NP On the / CeO2 catalyst, Pt is dispersed in the form of nanoclusters, and no single Pt atoms are observed. Figure 9 In Figure a, the diameter of a single Pt atom is less than 0.1 nm, and the diameter of a Pt nanocluster is about 2 nm.

[0085] The CO oxidation reaction stability performance test results of Example 1 of the present invention are shown in Figure 10 . Figure 10 The results show that 0.02Pt10.08Pt NP / CeO2 catalyst at high space velocity 3.0×10 4 mL·g cat -1 h -1 Under the conditions of 40 ℃ and 80 ℃, the reaction mixture showed good stability within 24 h, and the conversion rate was stable at about 80%.

Claims

1. A method for preparing a supported noble metal catalyst with a controllable single atom / nanocluster ratio, characterized in that: The active component noble metal in the catalyst coexists in the form of single atoms and nanoclusters, and the single atom / nanocluster ratio is controllable, including the following steps: 1) Dissolving the precursor of the noble metal M in deionized water, adding an organic complexing agent, and stirring to carry out a complex reaction to obtain a noble metal M precursor complex solution; The organic complexing agent in step 1) is at least one of ethylenediamine, sodium ethylenediaminetetraacetate, triethylamine, monoethanolamine, diethylenetriamine, and tetraethylenepentamine; In step 1), the molar amount of the organic complexing agent is (5 to 20) × 10 3 times; 2) adding a carrier to the solution in step 1), stirring thoroughly to load the complex onto the carrier, filtering, drying, and placing the resulting solid product in a Joule ultrafast heating device in a H2 atmosphere for rapid thermal shock to produce a single-atom catalyst; In step 2), the rapid thermal shock is achieved by Joule ultrafast heating, which rapidly raises the temperature to a heat treatment temperature of 500-800°C within 500 milliseconds, with a heat treatment time of 10-60 seconds, and then naturally cools to room temperature. 3) loading the noble metal M nanocluster sol onto the single atom catalyst in step 2) by a sol impregnation method to obtain a catalyst in which single atoms and nanoclusters of the noble metal M coexist; wherein the noble metal M is at least one of Pt, Rh, Ir, Ru, and Pd; The molar amount of noble metal M atoms in the catalyst accounts for 10-90% of the total amount of noble metal M atoms and nanoclusters; The loading amount of the noble metal M in the catalyst is 0.1 ~ 1%.

2. The method for preparing a supported noble metal catalyst with a controllable single atom / nanocluster ratio according to claim 1, wherein: Step 1) The temperature of the stirring complexation reaction is room temperature, and the reaction time is 1 to 5 hours.

3. The method for preparing a supported noble metal catalyst with a controllable single atom / nanocluster ratio according to claim 1, wherein: In step 2), the carrier is a metal oxide or a carbon carrier, and the metal oxide is CeO2, TiO2, MnO2, FeO x The carbon carrier is at least one of activated carbon and carbon nanotubes, and the stirring time in step 2) is 2 to 10 hours.

4. The method for preparing a supported noble metal catalyst with a controllable single atom / nanocluster ratio according to claim 3, wherein: The carrier is CeO2 or TiO2.

5. The method for preparing a supported noble metal catalyst with a controllable single atom / nanocluster ratio according to claim 1, wherein: The heat treatment temperature is 550-650°C, and the heat treatment time is 20-60 seconds.

6. The method for preparing a supported noble metal catalyst with a controllable single atom / nanocluster ratio according to claim 1, wherein: The specific steps of step 3) are as follows: diluting the nanocluster sol of the noble metal M with ethylene glycol, and adding the resulting solution dropwise to the single-atom catalyst while stirring evenly; then immersing the solution at room temperature for 10 to 20 hours, and then drying the sample in a vacuum oven to obtain a catalyst in which single atoms and nanoclusters of the noble metal M coexist.

7. The method for preparing a supported noble metal catalyst with a controllable single atom / nanocluster ratio according to claim 1, wherein: The molar amount of noble metal M atoms in the catalyst accounts for 10 to 50% of the total amount of noble metal M atoms and nanoclusters.

8. The method for preparing a supported noble metal catalyst with a controllable single atom / nanocluster ratio according to claim 7, wherein: The molar amount of noble metal M atoms in the catalyst accounts for 10 to 30% of the total amount of noble metal M atoms and nanoclusters.

9. The method for preparing a supported noble metal catalyst with a controllable single atom / nanocluster ratio according to claim 1, wherein: The loading amount of the noble metal M in the catalyst is 0.1 ~ 0.5%.

10. A supported noble metal catalyst with a controllable single atom / nanocluster ratio prepared by the preparation method according to any one of claims 1 to 9.

11. Use of the supported noble metal catalyst with controllable single atom / nanocluster ratio as claimed in claim 10 in catalyzing CO oxidation reaction.

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