A superdispersed Ag-CeO2 catalyst and its preparation method

Abstract

The application discloses an ultra-dispersed Ag-CeO2 catalyst, which is a nanorod structure catalyst with ultra-dispersed metal Ag loaded on CeO2; the XRD pattern of the Ag-CeO2 catalyst has no Ag characteristic peak, the TEM pattern of the Ag-CeO2 catalyst has no Ag particle at 5nm times, and the energy spectrum distribution diagram of the Ag-CeO2 catalyst has Ag in a dispersed state; wherein Ag represents silver, and CeO2 represents ceria. The application has the characteristics and beneficial effects that: by using the material and the preparation method, an Ag-CeO2 catalyst with an ultra-dispersed effect can be obtained by calcining at a low temperature in an oxygen atmosphere; the catalyst prepared by the application has a low reduction temperature, more oxygen vacancies, excellent catalytic performance, and important values in the fields of catalysis, energy, optics and the like.

Description

Technical Field

[0001] This invention relates to the field of nanomaterials technology, specifically to an ultradispersed Ag-CeO2 catalyst and its preparation method. Background Technology

[0002] Recent studies have demonstrated the excellent catalytic activity of supported catalysts. Compared to other noble metals, Ag-based catalysts have become more attractive and widely studied due to their higher stability, lower cost, and unique catalytic performance for various catalytic reactions. Cerium dioxide (CeO2), as an important rare earth oxide, has attracted much attention due to its high thermal stability, good oxygen storage capacity, redox properties, and strong metal-support interactions. It is widely used as a highly efficient and promising catalytic material, exhibiting excellent catalytic performance. It can better stabilize dispersed silver, leading to strong interactions between the metal and support. The geometric and electronic interactions at the metal-support interface affect the structure of the supported nanoparticles, giving them high metal dispersibility and catalytic activity. Therefore, Ag-CeO2 catalysts are promising catalysts with high catalytic activity and low cost commercial availability, and are widely used in catalysis, energy, optics, and other fields.

[0003] It is generally believed that the catalytic activity of Ag / CeO2 is mainly related to the morphology of the support, the dispersion of Ag, and the interaction between Ag and CeO2. Previous studies have shown that nanorod-structured CeO2 exhibits superior performance, as it is more effective at activating surface lattice oxygen, generating more oxygen vacancies, and promoting the catalytic activity of Ag / CeO2. Furthermore, smaller Ag particle size and higher dispersion result in higher catalytic activity, and the direction of electron transfer between Ag and the CeO2 support significantly affects the intrinsic catalytic activity of the catalyst. In existing technologies, heat treatment can significantly improve the catalytic activity of catalysts, but high temperatures easily lead to Ostwald ripening of the active component, causing sintering and growth of the active component particles and a decrease in catalyst activity. In most studies, Ag in Ag-CeO2 composites is supported on a CeO2 support, which can enhance interfacial interactions, but may reduce catalytic performance due to the sintering of Ag nanoparticles at high temperatures. Summary of the Invention

[0004] This invention addresses the problems in the prior art by disclosing an ultradispersed Ag-CeO2 catalyst and its preparation method. By designing an Ag-CeO2 catalyst structure with direct Ag-Ce bonding, this invention not only increases the silver loading (the mass ratio of Ag mass to the total mass of Ag and CeO2) but also overcomes the Ostwald ripening effect, refining large Ag particles into ultradispersed Ag, improving atom utilization, and enhancing catalytic activity.

[0005] This invention is achieved through the following technical solution:

[0006] This invention provides an ultradispersed Ag-CeO2 catalyst, wherein the Ag-CeO2 catalyst is a nanorod structure catalyst in which ultradispersed metallic Ag is supported on CeO2. The ultradispersed Ag-CeO2 catalyst has no Ag characteristic peaks in its XRD pattern, no Ag particles in its 5nm magnification TEM image, and Ag in a dispersed state in its energy dispersive spectroscopy distribution pattern; wherein Ag represents silver and CeO2 represents cerium dioxide.

[0007] In the above-described design of this invention, Ag in the Ag-CeO2 catalyst is ultradispersed and supported on a nanorod structure on CeO2. No characteristic peaks of Ag were observed in the XRD pattern of the Ag-CeO2 catalyst, and no silver atom particle packing was observed in the TEM image at 5 nm magnification. Furthermore, Ag dispersion was observed in the energy dispersive spectroscopy (EDS) pattern, indicating that the Ag particles are sufficiently dispersed on CeO2. The degree of dispersion in terms of morphology, size, and packing is lower than that that can be detected and observed by XRD. TEM and HAADF also confirmed this. The ultradispersion of Ag gives the Ag-CeO2 catalyst excellent catalytic performance.

[0008] As a further embodiment, the Ag loading (in this invention, the Ag loading is the mass ratio of Ag to the total mass of Ag and CeO2) is no higher than 14%. The catalyst of this invention has a higher Ag loading than existing technologies. This catalyst not only overcomes the Ag agglomeration that may result from excessively high loading, but also ensures that Ag is sufficiently dispersed on CeO2, resulting in better catalytic activity.

[0009] As a further embodiment, the diameter of the nanorod is 10nm-20nm.

[0010] As a further embodiment, the Ag-CeO2 catalyst exhibits characteristic XRD diffraction peaks at 28°, 34°, 48°, 57°, 69°, and 77°; the XPS energy distribution of the Ag-CeO2 catalyst shows characteristic peaks at 368.1 eV and 374.1 eV. While no characteristic Ag diffraction peaks were found in the XRD pattern, the energy distribution confirms the presence of Ag in the catalyst, indicating that Ag is hyperdispersed and supported on CeO2.

[0011] The present invention also provides a method for preparing the Ag-CeO2 catalyst, the method comprising:

[0012] S1: Preparation of Ce x Ag y Al zAlloy strip, where x, y, and z correspond to the atomic percentages of each alloying element, Ce represents cerium, Al represents aluminum, and 0.80≤x≤0.95, 0.05≤y≤0.2, z=4, and x+y+z=5;

[0013] S2: Ce x Ag y Al z The alloy ribbon was chemically dealloyed in a 5 mol / L-10 mol / L sodium hydroxide solution.

[0014] S3: Ce x Ag y Al z The powder product obtained after the alloy strip is de-alloyed is taken out, cleaned and dried to obtain the Ag-CeO2 intermediate with a nanorod structure.

[0015] S4: The obtained nanorod-shaped Ag-CeO2 was calcined at a temperature not exceeding 350°C in an oxygen atmosphere to obtain an ultradispersed Ag-CeO2 catalyst.

[0016] In this method, the combined effects of the atomic percentages of each alloying element, the sodium hydroxide concentration, and the calcination temperature promote the formation of a highly dispersed Ag-CeO2 catalyst. Specifically, the atomic percentage of Al is four times the sum of the atomic percentages of Ce and Ag, and the atomic percentage of Ce is 4 to 19 times that of Ag, which can promote the formation of a highly dispersed Ag-CeO2 catalyst. x Ag y Al z During the dealloying process with 5 mol / L-10 mol / L sodium hydroxide, the alloy ribbon rapidly forms suitable channels for oxygen introduction, promoting the partial oxidation of Ce to form CeO2. After drying, a powdery Ag-CeO2 intermediate with a nanorod-like structure is initially formed. Calcination of this nanorod-like Ag-CeO2 intermediate under an oxygen atmosphere facilitates the acquisition of CeO2 with better crystallinity. Furthermore, the direct bonding microstructure of Ag-Ce in Ag-CeO2 promotes the refinement and dispersion of Ag particles at low temperatures (not exceeding 350℃), overcoming the Ostwald ripening phenomenon and obtaining a super-dispersed nanorod-like Ag-CeO2 catalyst, thereby improving its catalytic activity. Moreover, the dealloying method is simpler and lower in cost than other methods, suitable for large-scale preparation, and the preparation process is more efficient and controllable. The prepared nanorod-like Ag-CeO2 catalyst material has a high specific surface area and uniform structure.

[0017] As a further option, the Ce x Ag y Al zThe preparation process of alloy ribbons includes following Ce x Ag y Al z The target components, Ce, Ag, and Al, were weighed out and mixed evenly to obtain the smelting raw material. Smelting was carried out under an argon protective atmosphere. After the raw material melted, smelting continued, then heating was stopped, and the alloy was allowed to cool and solidify in the crucible. The crucible was then turned over, and the process was repeated until a homogeneous master alloy ingot was obtained. The master alloy ingot was broken into small pieces, which were then placed in a quartz tube. Using a vacuum spinning device under an argon atmosphere, the molten alloy was sprayed onto a copper roller in a high-speed rotating vacuum spinning device to prepare Ce. x Ag y Al z Amorphous alloy thin strip.

[0018] As a further refinement, the melting time of the raw material is 100-140 seconds, the melting temperature is 1800℃-2200℃, the melting is repeated 3-5 times, and the vacuum degree of the vacuum belt spinning equipment is no greater than 9×10⁻⁶. -4 Pa, the linear speed of the copper roller is 2300r / min-2700r / min.

[0019] As a further embodiment, in S2, the chemical dealloying condition is maintained at a temperature of 25°C-35°C for 19-21 hours.

[0020] As a further embodiment, in step S3, the drying conditions are vacuum drying, the drying temperature is 65℃-75℃, and the drying time is 23h-25h. Drying is beneficial for the initial formation of Ag-CeO2 intermediates with nanorod-like structures, providing the basic conditions for the formation of stable Ag-CeO2 with nanorod-like structures by low-temperature calcination.

[0021] The features and beneficial effects of this invention are as follows: Using the materials and preparation method provided by this invention, an Ag-CeO2 catalyst with super-dispersion effect can be obtained by calcination at a low temperature under an oxygen atmosphere. The catalyst prepared by this invention has a low reduction temperature, a large number of oxygen vacancies, and excellent catalytic performance, and has important value in catalysis, energy, optics and other fields. Attached Figure Description

[0022] To more clearly illustrate the Ag-CeO2 catalyst in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention.

[0023] Figure 1 The image shows the XRD pattern of the alloy strip prepared in Example 1 of this invention.

[0024] Figure 2 The XRD patterns of the Ag-CeO2 catalyst prepared by the method of this invention after heat treatment in an oxygen atmosphere at calcination temperatures of 300°C and 500°C.

[0025] Figure 3 The images shown are TEM images, HAADF images, and energy dispersive spectroscopy (EDS) images of the Ag-CeO2 catalyst prepared in Example 1 of this invention after heat treatment at 300°C. Figure 3 a is a TEM image of the Ag-CeO2-300 catalyst; Figure 3 b is the HAADF diagram of the Ag-CeO2-300 catalyst; Figure 3 c- Figure 3 f is the elemental energy dispersive spectroscopy (EDS) diagram of the Ag-CeO2-300 catalyst.

[0026] Figure 4 The image shows the XRD pattern of the catalyst of Comparative Example 1 of this invention.

[0027] Figure 5 XPS images of the catalysts prepared in Examples 1 and 2 of this invention.

[0028] Figure 6 The above are H-TPR diagrams of the catalysts prepared in Examples 1, 2 and Comparative Example 1 of this invention. Detailed Implementation

[0029] To facilitate understanding of the ultradispersed Ag-CeO2 catalyst and its preparation method of the present invention, a more comprehensive description of the ultradispersed Ag-CeO2 catalyst and its preparation method of the present invention will be given below, and embodiments of the present invention will be provided, but this does not limit the scope of the present invention.

[0030] The present invention compares the catalytic effect of the Ag-CeO2 catalyst prepared by the method of the present invention through the following examples and comparative examples.

[0031] Example 1: According to Ce 0.81 Ag 0.19 The target composition of Al4 is obtained by weighing Ce, Ag, and Al, mixing them evenly to obtain the smelting raw material, with each element having a purity greater than 99.8%. The smelting raw material is placed in a vacuum arc melting furnace and smelted under an argon protective atmosphere. After the raw material melts, smelting continues for 2 minutes, then heating is stopped, allowing the alloy to cool and solidify with the crucible. The crucible is then turned over, and this smelting process is repeated 5 times. After cooling, a homogeneous master alloy ingot is obtained. The obtained master alloy ingot is broken into small pieces, and these pieces are placed in quartz tubes with an opening diameter of 1–2 mm and fixed within the induction coil of a vacuum belt spinning device. The distance between the quartz tube and the copper roller is adjusted, the cavity is closed, and the vacuum level of the cavity is ≤9 × 10⁻⁶. -4Pa is filled with inert argon gas as a protective atmosphere, and the pressure difference between the inside and outside of the cavity is adjusted. The alloy block is melted using induction melting, and the molten alloy liquid is then sprayed onto a copper roller at a line speed of 2500 r / min using the pressure difference to obtain an amorphous alloy strip. The melting temperature is approximately 2000℃. The obtained Ce... 0.81 Ag 0.19 Al4 alloy ribbons were placed in a 5 mol / L sodium hydroxide solution and left at 30°C for 20 hours for chemical dealloying. Ce... 0.81 Ag 0.19 The powder product obtained after dealloying Al4 alloy strips was taken out, repeatedly washed and dried to obtain an Ag-CeO2 intermediate with a silver loading of 13% in a nanorod structure. The dried Ag-CeO2 intermediate was calcined at 300℃ for 3h in an oxygen atmosphere to obtain the Ag-CeO2-300 catalyst. The 300 in Ag-CeO2-300 catalyst represents 300℃, which is to distinguish it from Ag-CeO2 catalysts prepared at other temperatures.

[0032] Example 2: According to Ce 0.81 Ag 0.19 The target composition of Al4 is obtained by weighing Ce, Ag, and Al, mixing them evenly to obtain the smelting raw material, with each element having a purity greater than 99.8%. The smelting raw material is placed in a vacuum arc melting furnace and smelted under an argon protective atmosphere. After the raw material melts, smelting continues for 2 minutes, then heating is stopped, allowing the alloy to cool and solidify with the crucible. The crucible is then turned over, and this smelting process is repeated 5 times. After cooling, a homogeneous master alloy ingot is obtained. The obtained master alloy ingot is broken into small pieces, and these pieces are placed in quartz tubes with an opening diameter of 1–2 mm and fixed within the induction coil of a vacuum belt spinning device. The distance between the quartz tube and the copper roller is adjusted, the cavity is closed, and the vacuum level of the cavity is ≤9 × 10⁻⁶. -4 Pa is filled with inert argon gas as a protective atmosphere, and the pressure difference between the inside and outside of the cavity is adjusted. The alloy block is melted using induction melting, and the molten alloy liquid is then sprayed onto a copper roller at a line speed of 2500 r / min using the pressure difference to obtain an amorphous alloy strip. The melting temperature is approximately 2000℃. The obtained Ce... 0.81 Ag 0.19 Al4 alloy ribbons were placed in a 5 mol / L sodium hydroxide solution and left at 30°C for 20 hours for chemical dealloying. Ce... 0.81 Ag 0.19 The powder product obtained after dealloying Al4 alloy strips was taken out, repeatedly washed and dried to obtain a nanorod-shaped Ag-CeO2 intermediate; the dried Ag-CeO2 intermediate was calcined at 500℃ for 3h in an oxygen atmosphere to obtain Ag-CeO2-500 catalyst.

[0033] Comparative Example 1:

[0034] The Ag / CeO2 catalyst was prepared by impregnation method. First, the CeO2 prepared by alloy strip preparation method of the present invention was used. 10 Al 90 The alloy strip is de-alloyed to remove Al. The dried material is then immersed in AgNO3 solution for 5 hours. After drying, the immersed material is calcined in a muffle furnace at 500°C for 1 hour to remove NO3. - Ag / CeO2 catalyst was obtained. The prepared catalyst was then calcined at 300°C in an oxygen atmosphere to obtain Ag / CeO2-300 catalyst.

[0035] We further compared the CO oxidation performance of the catalysts obtained by different methods. The specific operation process is as follows: The CO oxidation reaction performance of the Ag-CeO2 intermediate in Example 1, the Ag-CeO2-300 catalyst prepared in Example 1, the Ag-CeO2-500 catalyst prepared in Example 2, the Ag / CeO2 catalyst in Comparative Example 1, and the Ag / CeO2-300 catalyst prepared in Comparative Example 1 were tested. The test conditions consisted of 1% CO, 10% O2 (CO: 5 mL / min, O2: 50 mL / min, Ar: 50 mL / min, total 105 mL / min), and a space velocity of 315000 mL / (h·g).

[0036] Results and Analysis

[0037] Table 1. Comparison of CO oxidation performance of catalysts prepared in the examples and comparative examples.

[0038]

[0039] We obtain Ce using the method of this invention. 0.81 Ag 0.19 Al4 alloy thin strip, such as Figure 1 As shown, Figure 1 For Ce 0.81 Ag 0.19 XRD pattern of Al4 alloy strip, Ce 0.81 Ag 0.19 Al4 alloy thin strips are mainly composed of Ag3Al 17A multiphase mixture of Ce5, CeAl4, and Ce was used to prepare an ultradispersed Ag-CeO2 catalyst (Ag-CeO2-300 catalyst) using a combination of dealloying and low-temperature calcination, as described in Example 1. In the catalyst preparation process of this invention, low-temperature calcination facilitates the ultradispersion of the Ag component supported on the CeO2 surface, thereby fully utilizing the catalyst's catalytic activity. Furthermore, the calcination temperature is a key factor affecting Ag dispersion. Higher calcination temperatures may lead to Ostwald ripening, resulting in Ag agglomeration and a decrease in catalyst activity. We further investigated the effects of different calcination temperatures on the activity and dispersibility of the final catalyst. As described in Example 2, we obtained the Ag-CeO2-500 catalyst using a calcination temperature of 500°C. We plotted the Ag-CeO2 intermediate prepared in Example 1, the Ag-CeO2-300 catalyst prepared in Example 1, and the Ag-CeO2-500 catalyst prepared in Example 2 in X-ray powder diffraction patterns expressed as diffraction angle 2θ, as shown below. Figure 2 As shown, we found that the Ag-CeO2 intermediate and the Ag-CeO2-500 catalyst prepared in Example 2 exhibited a characteristic Ag diffraction peak at 38°, while the Ag-CeO2-300 catalyst prepared in Example 1 did not show a characteristic Ag diffraction peak at 38°. We believe that Ag hyperdispersion occurred at a calcination temperature of 300°, with the hyperdispersion Ag loaded on CeO2; and that at too high a calcination temperature (500°), Ostwald ripening occurred, leading to Ag sintering. To further verify our hypothesis, the Ag-CeO2-300 catalyst prepared in Example 1 was characterized by transmission electron microscopy, and the TEM and HAADF images of the Ag-CeO2-300 catalyst were obtained, as shown below. Figure 3 As shown. From Figure 3 As can be seen from a, the prepared Ag-CeO2-300 catalyst sample has a nanorod structure. Figure 3 Further observation in b reveals that the stripe spacing in the photograph matches the interplanar spacing of CeO2, while no stripes matching the interplanar spacing of Ag were found. Figure 3 The elemental energy dispersive spectroscopy (EDS) diagram of the Ag-CeO2-300 catalyst (cf) further reveals the hyperdispersion of Ag in the catalyst, showing that Ag is hyperdispersed on CeO2 nanorod supports. It is evident that the Ag-CeO2 intermediate prepared by the method described in this invention undergoes reverse Ostwald ripening during low-temperature calcination, dispersing the active component Ag from nanoparticles into sub-nanometer hyperdispersed Ag clusters, thus obtaining hyperdispersed Ag supported on CeO2 nanorods.

[0040] We further investigated the preparation of Ag / CeO2 catalysts using the impregnation method. The obtained Ag / CeO2 catalysts were calcined at the calcination temperature of this invention, as shown in Comparative Example 1, to verify whether the calcination temperature of this invention can also promote the hyperdispersion of Ag on CeO2 in catalysts obtained by other preparation methods. We compared the X-ray powder diffraction patterns of the Ag / CeO2 catalyst before low-temperature calcination (300℃) in Comparative Example 1 and the Ag / CeO2-300 catalyst prepared in Comparative Example 1, expressed in terms of diffraction angle 2θ, as shown in the diagram. Figure 4 As shown, it can be found that the Ag / CeO2 catalyst and the Ag / CeO2-300 catalyst prepared in Comparative Example 1 still have the characteristic Ag diffraction peak at 38°. This shows that the ultradispersed Ag obtained in this invention is not only related to the calcination temperature. In traditional methods, such as the impregnation method in Comparative Example 1, Ag / CeO2 catalysts are prepared by direct Ag-O bonding, with electrons transferring from Ag to O. However, in the preparation process of this invention, within the atomic percentage range of each alloying element in the alloy strip design, a ternary alloy solid solution material with uniform Ag, Ce, and Al can be obtained first through high-temperature melting, where Ag-Ce are bonded by metallic bonds. Then, the Al element in the ternary alloy is removed by dealloying to obtain an Ag-CeO2 intermediate with direct Ag-Ce bonding, where electrons transfer from Ce to Ag. The enrichment of negative charges on the Ag surface promotes the exchange and diffusion of surface oxygen and subsurface oxygen in Ag, which may lead to the superdispersion of Ag particles during low-temperature calcination (not exceeding 350℃), resulting in a more stable nanorod-shaped superdispersed Ag-CeO2 catalyst, thereby improving the catalytic activity of the Ag-CeO2 catalyst. All of these factors are inseparable from the atomic percentages of the alloying elements and the concentration of sodium hydroxide we select. Only with appropriate atomic percentages and sodium hydroxide concentrations can the nanorod-like Ag-CeO2 intermediate be formed, which is conducive to achieving ultra-dispersion of Ag particles under low-temperature calcination.

[0041] We further compared the CO oxidation performance of the various catalysts prepared above, and the results are shown in Table 1. As can be seen from Table 1, the Ag-CeO2-300 catalyst prepared in this invention exhibits better catalytic performance than other catalysts, with a higher To for CO oxidation. 50 The T value of the Ag / CeO2 catalyst obtained by the conventional impregnation method for CO oxidation is 80℃. 50 The temperature is 160℃; the catalyst prepared in this invention catalyzes the oxidation of CO at a T value of 160℃. 100 The T value for CO oxidation catalyzed by the Ag / CeO2 catalyst obtained by the conventional method is 130℃. 100The temperature was 182℃. It is evident that the catalyst prepared in this invention exhibits significantly higher activity. To investigate the reason for the increased catalytic activity, the XPS diagram of the Ag-CeO2-300 catalyst prepared in this invention was analyzed. Figure 5 As shown in the figure, the binding energies of Ag 3d5 / 2 and Ag 3d3 / 2 orbitals in the Ag-CeO2 intermediate, Ag-CeO2-300, and Ag-CeO2-500 all differ by 6 eV, indicating that Ag exists in a metallic state in these materials. Furthermore, the Ag 3d5 / 2 binding energy of the Ag-CeO2 intermediate is 367.9 eV, lower than the standard value of 368.2 eV, indicating that Ag gains electrons, indirectly proving the formation of Ag-Ce bonds. In addition, the Ag 3d5 / 2 orbital binding energy of the Ag-CeO2-300 catalyst increases to 368.1 eV, closer to the standard value, due to the hyperdispersion of Ag promoting the formation of more Ag-O bonds, thus increasing the Ag 3d orbital electron binding energy. This invention also conducted characterization tests on H2-TPR, such as... Figure 6 As shown, the Ag-CeO2-300 catalyst has a lower reduction temperature and better activity of surface oxygen species. This is attributed to the fact that the ultra-dispersed Ag better promotes the reduction of the reduction temperature. Under the combined influence of these factors, the catalytic activity of the Ag-CeO2-300 catalyst is improved.

[0042] In summary, the Ag-CeO2 catalyst prepared by this invention has ultra-dispersed Ag supported on CeO2 nanorods, resulting in a lower reduction temperature, more oxygen vacancies, and excellent catalytic performance, which is of great value in catalysis, energy, optics and other fields.

[0043] It should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A superdispersed Ag-CeO2 catalyst, characterized in that, The Ag-CeO2 catalyst is a nanorod structure catalyst in which ultradispersed metallic Ag is supported on CeO2. The XRD pattern of the ultradispersed Ag-CeO2 catalyst has no characteristic Ag peaks, and no Ag particles are present in the TEM image at 5 nm magnification. Moreover, Ag is in a dispersed state in the energy spectrum distribution. Where Ag represents silver and CeO2 represents cerium dioxide; The preparation method of the ultradispersed Ag-CeO2 catalyst includes: S1: Preparation of Ce x Ag y Al z Alloy strip, where x, y, and z correspond to the atomic percentages of each alloying element, Ce represents cerium, Al represents aluminum, and 0.80≤x≤0.95, 0.05≤y≤0.2, z=4, and x+y+z=5; S2: Ce x Ag y Al z The alloy ribbon was chemically dealloyed in a 5 mol / L-10 mol / L sodium hydroxide solution. S3: Ce x Ag y Al z The powder product formed after the alloy strip is de-alloyed is taken out, cleaned and dried to obtain the Ag-CeO2 intermediate with a nanorod structure. S4: The obtained nanorod-shaped Ag-CeO2 was calcined at a temperature not exceeding 350°C in an oxygen atmosphere to obtain an ultradispersed Ag-CeO2 catalyst.

2. The ultradispersed Ag-CeO2 catalyst according to claim 1, characterized in that, The Ag loading is no more than 14%.

3. The ultradispersed Ag-CeO2 catalyst according to claim 1, characterized in that, The diameter of the nanorods is 10 nm-20 nm.

4. The ultradispersed Ag-CeO2 catalyst according to claim 1, characterized in that, The Ag-CeO2 catalyst has characteristic XRD diffraction peaks at 28°, 34°, 48°, 57°, 69°, and 77°; the XPS energy spectrum of the Ag-CeO2 catalyst has characteristic peaks at 368.1 eV and 374.1 eV.

5. The method for preparing the ultradispersed Ag-CeO2 catalyst according to any one of claims 1-4, characterized in that, The method includes: S1: Preparation of Ce x Ag y Al z Alloy strip, where x, y, and z correspond to the atomic percentages of each alloying element, Ce represents cerium, Al represents aluminum, and 0.80≤x≤0.95, 0.05≤y≤0.2, z=4, and x+y+z=5; S2: Ce x Ag y Al z The alloy ribbon was chemically dealloyed in a 5 mol / L-10 mol / L sodium hydroxide solution. S3: Ce x Ag y Al z The powder product formed after the alloy strip is de-alloyed is taken out, cleaned and dried to obtain the Ag-CeO2 intermediate with a nanorod structure. S4: The obtained nanorod-shaped Ag-CeO2 was calcined at a temperature not exceeding 350°C in an oxygen atmosphere to obtain an ultradispersed Ag-CeO2 catalyst.

6. The preparation method according to claim 5, characterized in that, The preparation of S1 Ce x Ag y Al z The process of alloying thin strips includes following Ce x Ag y Al z The target components, Ce, Ag, and Al, were weighed out and mixed evenly to obtain the smelting raw material. Smelting was carried out under an argon protective atmosphere. After the raw material melted, smelting continued, then heating was stopped, and the alloy was allowed to cool and solidify in the crucible. The crucible was then turned over, and the process was repeated until a homogeneous master alloy ingot was obtained. The master alloy ingot was broken into small pieces, which were then placed in a quartz tube. Using a vacuum spinning device under an argon atmosphere, the molten alloy was sprayed onto a copper roller in a high-speed rotating vacuum spinning device to prepare Ce. x Ag y Al z Alloy strip.

7. The preparation method according to claim 6, characterized in that, The raw material is melted and then continuously smelted for 100-140 seconds at a temperature of 1800℃-2200℃. The smelting process is repeated 3-5 times, and the vacuum degree of the vacuum belt spinning equipment is no greater than 9×10⁻⁶. -4 Pa, the linear speed of the copper roller is 2300 r / min-2700 r / min.

8. The preparation method according to claim 5, characterized in that, In S2, the chemical dealloying condition is maintained at 25℃-35℃ for 19-21 h.

9. The preparation method according to claim 5, characterized in that, In step S3, the drying conditions are vacuum drying, the drying temperature is 65℃-75℃, and the drying time is 23 h-25 h.

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