Cerium-regulated potassium-manganese composite metal oxide catalyst with hollow nanotube structure and preparation method and application thereof

Abstract

The application discloses a cerium-regulated potassium-manganese composite metal oxide catalyst with a hollow nanotube structure, which is a cerium-regulated potassium-manganese composite metal oxide catalyst with a hollow nanotube structure and is composed of a composite metal potassium-manganese, potassium-manganese-cerium and oxygen. The application applies a centrifugal spinning method to the preparation of a morphology of a hollow nanotube metal oxide catalyst and catalytic combustion of carbon smoke. In the preparation method, low-cost metal nitrate and metal acetate are selected as metal precursors, polyvinylpyrrolidone is used as a template agent, and a cerium-regulated potassium-manganese composite metal oxide catalyst with a hollow nanotube structure is obtained through dissolution-centrifugal spinning-drying-calcination. The preparation method can be applied to the preparation of various composite metal oxide catalysts and has the advantages of simple preparation process, strong practicability, high efficiency, low cost and easy realization of large-scale production.

Description

Technical Field

[0001] This invention belongs to the field of catalyst material preparation technology, and particularly relates to a cerium-regulated potassium-manganese composite metal oxide catalyst with a hollow nanotube structure, its preparation method, and its application. Background Technology

[0002] Diesel engines, due to their advantages such as good economy, high fuel efficiency, and low carbon dioxide emissions, are widely used in heavy industries such as transportation, agriculture, and construction. However, the soot particles emitted from their exhaust are not only a major cause of smog but also pose a significant threat to the human respiratory, cardiovascular, and circulatory systems, making it one of the most important issues in air pollution control. In recent decades, aftertreatment technology has become the primary means of controlling diesel engine soot emissions. Diesel particulate filters (DPFs) capture soot particles that have not yet entered the atmosphere and regenerate them at relatively low operating temperatures. The design and preparation of soot combustion catalysts coated on the DPF surface have become a key aspect of aftertreatment technology. Therefore, developing novel catalysts with low cost and excellent catalytic performance is one of the main challenges in the application of aftertreatment technology, and research on the catalytic combustion of soot particles has significant environmental protection implications.

[0003] As a deep redox reaction involving gas (reactant gas) - solid (smoke particles) - solid (catalyst), the catalytic combustion of soot relies heavily on two key factors influencing catalyst performance: intrinsic activity and contact efficiency with soot. To enhance intrinsic activity, researchers have investigated various catalysts with different compositions. Among these, cerium-based catalysts from rare earth metals possess unique oxygen storage and release capabilities, while manganese-based catalysts from transition metals exhibit excellent redox capabilities due to their diverse and variable valence states. Both are considered to have broad application prospects in the study of catalytic combustion of soot. Meanwhile, to enhance the contact between the catalyst and soot, researchers have been working to synthesize catalysts with special morphologies using simple and easy preparation methods. Among them, hollow nanotube catalysts, due to their extraordinary aspect ratio and hollow structure, have shown advantages that other nanomaterials cannot match. Their high specific surface area allows the active sites of the catalyst to be fully exposed, and the pores and interconnected channels between the fibers can achieve high mass transfer efficiency. The interwoven network structure makes it easier for soot particles to be captured, thereby improving the contact efficiency between soot particles and catalysts, which has attracted the attention and research of researchers.

[0004] In summary, providing a simple, practical, and efficient method for preparing various composite metal oxide catalysts is a problem that urgently needs to be solved. Summary of the Invention

[0005] In view of this,

[0006] The technical solution provided by the present invention is as follows: Firstly, the present invention provides a cerium-regulated potassium-manganese composite metal oxide catalyst with a hollow nanotube structure. The catalyst is a cerium-regulated hollow nanotube structure potassium-manganese composite metal oxide catalyst, which is composed of composite metal potassium-manganese, potassium-manganese-cerium and oxygen.

[0007] Furthermore, the catalyst: K 0.3 MnO δ The molar ratio of K to Mn is 0.3:1; K 0.3x Mn x Ce 1-x O δ The molar ratio of K to Mn is 0.3:1, and the molar ratios of Mn to Ce are 1:9, 3:7, 5:5, 7:3, and 9:1, respectively.

[0008] Furthermore, the catalyst is K. 0.3 MnO δ K 0.03 Mn 0.1 Ce 0.9 O δ K 0.09 Mn 0.3 Ce 0.7 O δ K 0.15 Mn 0.5 Ce 0.5 O δ K 0.21 Mn 0.7 Ce 0.3 O δ K 0.27 Mn 0.9 Ce 0.1 O δ .

[0009] Secondly, the present invention provides a method for preparing the cerium-regulated potassium-manganese composite metal oxide catalyst, comprising: using metal nitrates and metal acetates as metal precursors, using polyvinylpyrrolidone as a template agent, and preparing the catalyst by centrifugal spinning.

[0010] Furthermore, the average molecular weight of the polyvinylpyrrolidone is 1,300,000, and K = 88-96.

[0011] Further, according to the stoichiometric ratio, metal nitrate and metal acetate were weighed and dissolved in ethanol and water. After obtaining a clear solution, polyvinylpyrrolidone was added, and the mixture was stirred in a water bath for 30 minutes and then collected as a homogeneous transparent sol-like precursor.

[0012] The collected precursor sol was slowly injected into the centrifuge of a centrifugal spinning device. After solvent evaporation and drying at 6000 rpm, the precursor fibers were collected at a distance of 13.5 cm from the centrifuge. The collected fibers were dried and then calcined to obtain hollow nanotube metal oxide catalysts.

[0013] Furthermore, the temperature of the water bath is 55°C.

[0014] Furthermore, the dried fibers are placed in a muffle furnace for calcination, wherein the muffle furnace is heated to 300°C at a heating rate of 2°C / min, maintained for 1 hour, then heated to 550°C within 20 minutes, and calcined at 550°C for 6 hours.

[0015] Thirdly, the present invention provides an application of the catalyst, wherein the catalyst is used in the catalytic combustion reaction of soot particles in diesel engine exhaust.

[0016] This invention provides a cerium-modified potassium-manganese composite metal oxide catalyst with a hollow nanotube structure, its preparation method, and its applications. The centrifugal spinning method is applied to the preparation of hollow nanotube metal oxide catalyst morphology and its use in catalytic combustion of carbon soot. The preparation method utilizes low-cost metal nitrates and metal acetates as metal precursors and polyvinylpyrrolidone as a template agent. The cerium-modified hollow nanotube structure potassium-manganese composite metal oxide catalyst is obtained through a process of dissolution-centrifugal spinning-drying-calcination. The preparation method provided by this invention can be applied to the preparation of various types of composite metal oxide catalysts, and has the advantages of simple preparation process, high practicality, high efficiency, low cost, and easy large-scale production.

[0017] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and do not limit the disclosure of the present invention. Attached Figure Description

[0018] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 The XRD pattern of the hollow nanotube structure single metal oxide catalyst provided in the embodiments of the present invention;

[0021] Figure 2 Scanning electron microscope (SEM) images of hollow nanotube-structured composite metal oxide catalysts provided in the embodiments of this invention;

[0022] Figure 3 K provided for the embodiments of the present invention 0.15 Mn 0.5 Ce 0.5 O δ Scanning electron microscope image of the catalyst. Detailed Implementation

[0023] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numerals in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. Rather, they are merely examples of systems consistent with some aspects of the invention as detailed in the appended claims.

[0024] This embodiment provides a method for preparing a cerium-modified hollow nanotube structure potassium-manganese composite metal oxide catalyst. Firstly, this series of materials are metal oxide catalysts with a composite structure, wherein the catalyst material is composed of composite metals (potassium manganese, potassium manganese cerium) and oxygen. The nanotube metal oxide catalyst mainly utilizes inexpensive metal nitrates and metal acetates as raw materials, and polyvinylpyrrolidone as a template agent. A carbon soot particle catalytic combustion catalyst with a special nanotube structure and high redox performance is obtained through centrifugal spinning. The preparation method involved in this invention has low equipment cost, a simple preparation environment, and the prepared nanotube structure metal oxide catalyst has the advantages of simple preparation process, high efficiency, low energy consumption, and easy large-scale production.

[0025] Specifically, it includes: a composite metal oxide catalyst having a hollow nanotube structure with uniformly distributed nanoneedles on its surface, composed of a composite metal (potassium manganese, potassium manganese cerium) and oxygen.

[0026] Composite metal oxide catalyst: K 0.3 MnO δ The molar ratio of K to Mn is 0.3:1, K 0.3x Mn x Ce 1-x O δIn this embodiment, the molar ratio of K:Mn is always kept at 0.3:1, and the molar ratio of Mn:Ce is 1:9, 3:7, 5:5, 7:3, and 9:1, respectively. Keeping the molar ratio of K:Mn at 0.3:1 ensures that the K-OMS-2 crystal form formed at this molar ratio has the best catalytic activity for the catalytic combustion of soot. At the same time, this embodiment explores how different manganese-cerium ratios can determine the optimal synergistic ratio between the K-OMS-2 crystal form and CeO2.

[0027] The preparation process uses metal nitrates and metal acetates as raw materials and polyvinylpyrrolidone as a template agent. The nanotube structure metal oxide catalyst is obtained through dissolution-centrifugal spinning-drying-calcination.

[0028] The average molecular weight of polyvinylpyrrolidone in the raw material is 1,300,000, and K = 88-96, which increases the viscosity of the precursor solution to facilitate centrifugal spinning.

[0029] The preparation method of the above-mentioned material specifically includes the following steps:

[0030] A certain amount of metal nitrate and metal acetate were weighed according to stoichiometric ratio and dissolved in a certain amount of ethanol and water. After obtaining a clear solution, polyvinylpyrrolidone was added, and the mixture was stirred for 30 minutes in a water bath (55℃) to obtain a homogeneous transparent sol-like precursor, which was collected using a medical registration device. The collected precursor sol was slowly injected into the centrifuge of a centrifugal spinning device. At a speed of 6000 rpm, the precursor sol was ejected from a small hole on the side of the rotor under centrifugal force. After solvent evaporation and drying and solidification, the precursor fibers were collected at a distance of 13.5 cm from the centrifuge using a collecting rod. The collected fibers were dried in an oven at 80℃ for 24 hours. The dried fibers were then calcined in a muffle furnace to obtain a hollow nanotube metal oxide catalyst.

[0031] The muffle furnace was heated to 300℃ at a heating rate of 2℃ / min, maintained for 1 hour, then heated to 550℃ within 20 minutes, and calcined at 550℃ for 6 hours.

[0032] In existing technologies, the preparation of fibrous composite metal oxide catalysts using centrifugal spinning has not been widely applied, mainly due to two limitations: the viscosity of the precursor sol and the temperature and humidity of the preparation environment. The high temperature and humidity provided in this embodiment are conducive to the success of centrifugal spinning. The process of preparing fibrous composite metal oxide catalysts using centrifugal spinning avoids the high temperature, high pressure, and high voltage requirements of the preparation environment, and has advantages such as simple equipment, low energy consumption, and process safety. At the same time, the centrifugal spinning process has high preparation efficiency, and the diameter of the prepared fibers can be appropriately adjusted by controlling the centrifugal speed and jet orifice diameter.

[0033] To better illustrate the technical means and product effects of the present invention, the preferred embodiments of the present invention will be described below.

[0034] Example 1

[0035] Preparation of K 0.3 MnO δ Nanotube-structured catalysts

[0036] 0.5888 g of potassium acetate and 4.9018 g of manganese acetate tetrahydrate were dissolved in a mixed solution of 8 mL of ethanol and 2 mL of water. After obtaining a homogeneous and transparent solution, 2 g of polyvinylpyrrolidone (Kw = 1300000) was dissolved in the above solution. The mixture was magnetically stirred for 30 min in a water bath at 55 °C to obtain a homogeneous sol-like precursor. After sonication for 10 min, the precursor was transferred to a medical syringe. A commercial cotton candy machine was used, and the speed was adjusted to 6000 rpm at room temperature. The precursor sol from the medical syringe was slowly and uniformly pushed into the rotor. Under the action of centrifugal force, the precursor fibers were ejected from a small hole on the side of the rotor and collected with a collecting rod at a distance of 13.5 cm from the rotor. The collected fibers were dried at 80℃ for 12 hours, then calcined in a muffle furnace under air atmosphere. The temperature was increased from room temperature to 300℃ at a rate of 2℃ / min. After calcination for 1 hour, the temperature was increased to 550℃ over 20 minutes, and then calcined at 550℃ for 6 hours before being cooled to room temperature to obtain K. 0.3 MnO δ Nanotube-structured metal oxide catalysts.

[0037] K 0.3 MnO δ XRD pattern of hollow nanotube catalyst as shown in Figure Figure 1 As shown in the figure, the catalyst exhibits a clear cryptopotassium manganese oxide-type Ka. 2-x Mn8O 16 Characteristic diffraction peaks of the sodium manganite type K2Mn4O8 crystal form. Its SEM image is shown below. Figure 2 As shown, the catalyst exhibits a hollow nanotube structure with uniformly distributed nanoneedle-like structures on its surface. The activity of this catalyst in catalyzing the combustion of soot particles is shown in Table 1.

[0038] Example 2

[0039] Preparation of K 0.03 Mn 0.1 Ce 0.9 O δ Nanotube-structured catalysts

[0040] 0.0329 g of potassium acetate, 0.2737 g of manganese acetate tetrahydrate, and 4.3633 g of cerium nitrate hexahydrate were dissolved in a mixed solution of 8 mL ethanol and 2 mL water. After obtaining a homogeneous and transparent solution, 1.65 g of polyvinylpyrrolidone (Kw = 1300000) was dissolved in the above solution. The mixture was magnetically stirred for 30 min in a water bath at 55 °C to obtain a homogeneous sol-like precursor. After sonication for 10 min, the precursor was transferred to a medical syringe. A commercial cotton candy machine was used, and the speed was adjusted to 6000 rpm at room temperature. The precursor sol from the medical syringe was slowly and uniformly pushed into the rotor. Under centrifugal force, the precursor fibers were ejected from a small hole on the side of the rotor and collected with a collecting rod at a distance of 13.5 cm from the rotor. The collected fibers were dried at 80℃ for 12 hours, then calcined in a muffle furnace under air atmosphere. The temperature was increased from room temperature to 300℃ at a rate of 2℃ / min. After calcination for 1 hour, the temperature was increased to 550℃ over 20 minutes, and then calcined at 550℃ for 6 hours before being cooled to room temperature to obtain K. 0.03 Mn 0.1 Ce 0.9 O δ Nanotube-structured metal oxide catalysts.

[0041] K 0.03 Mn 0.1 Ce 0.9 O δ XRD pattern of hollow nanotube catalyst as shown in Figure Figure 1 As shown in the figure, the catalyst exhibits obvious characteristic diffraction peaks of the CeO2 crystal form. Its SEM image is shown below. Figure 2 As shown, the catalyst exhibits a porous fibrous structure with an average diameter of 4.32 μm. The activity of this catalyst in catalyzing the combustion of soot particles is shown in Table 1.

[0042] Example 3

[0043] Preparation of K 0.09 Mn 0.3 Ce 0.7 O δ Nanotube-structured catalysts

[0044] 0.0932 g of potassium acetate, 0.7758 g of manganese acetate tetrahydrate, and 3.2069 g of cerium nitrate hexahydrate were dissolved in a mixed solution of 8 mL ethanol and 2 mL water. After obtaining a homogeneous and transparent solution, 1.7 g of polyvinylpyrrolidone (Kw = 1300000) was dissolved in the above solution. The mixture was magnetically stirred for 30 min in a water bath at 55 °C to obtain a homogeneous sol-like precursor. After sonication for 10 min, the precursor was transferred to a medical syringe. A commercial cotton candy machine was used, and the speed was adjusted to 6000 rpm at room temperature. The precursor sol from the medical syringe was slowly and uniformly pushed into the rotor. Under centrifugal force, the precursor fibers were ejected from a small hole on the side of the rotor and collected with a collecting rod at a distance of 13.5 cm from the rotor. The collected fibers were dried at 80℃ for 12 hours, then calcined in a muffle furnace under air atmosphere. The temperature was increased from room temperature to 300℃ at a rate of 2℃ / min. After calcination for 1 hour, the temperature was increased to 550℃ over 20 minutes, and then calcined at 550℃ for 6 hours before being cooled to room temperature to obtain K. 0.09 Mn 0.3 Ce 0.7 O δ Nanotube-structured metal oxide catalysts.

[0045] K 0.09 Mn 0.3 Ce 0.7 O δ XRD pattern of hollow nanotube catalyst as shown in Figure Figure 1 As shown in the figure, the catalyst exhibits obvious characteristic diffraction peaks of the CeO2 crystal form. Its SEM image is shown below. Figure 2 As shown, the catalyst exhibits a beaded fibrous structure, and its activity in catalyzing the combustion of soot particles is shown in Table 1.

[0046] Example 4

[0047] Preparation of K 0.15 Mn 0.5 Ce 0.5 O δ Nanotube-structured catalysts

[0048] 0.2944 g of potassium acetate, 2.4509 g of manganese acetate tetrahydrate, and 4.3422 g of cerium nitrate hexahydrate were dissolved in a mixed solution of 8 mL ethanol and 2 mL water. After obtaining a homogeneous and transparent solution, 1.8 g of polyvinylpyrrolidone (Kw = 1300000) was dissolved in the above solution. The mixture was magnetically stirred for 30 min in a water bath at 55 °C to obtain a homogeneous sol-like precursor. After sonication for 10 min, the precursor was transferred to a medical syringe. A commercial cotton candy machine was used, and the speed was adjusted to 6000 rpm at room temperature. The precursor sol from the medical syringe was slowly and uniformly pushed into the rotor. Under centrifugal force, the precursor fibers were ejected from a small hole on the side of the rotor and collected with a collecting rod at a distance of 13.5 cm from the rotor. The collected fibers were dried at 80℃ for 12 hours, then calcined in a muffle furnace under air atmosphere. The temperature was increased from room temperature to 300℃ at a rate of 2℃ / min. After calcination for 1 hour, the temperature was increased to 550℃ over 20 minutes, and then calcined at 550℃ for 6 hours before being cooled to room temperature to obtain K. 0.15 Mn 0.5 Ce 0.5 O δ Nanotube-structured metal oxide catalysts.

[0049] K 0.15 Mn 0.5 Ce 0.5 O δ XRD pattern of hollow nanotube catalyst as shown in Figure Figure 1 As shown in the figure, the catalyst exhibits obvious CeO2 and crypto-potassium manganese oxide-type K2O. 2-x Mn8O 16 Characteristic diffraction peaks of the crystal form. Its SEM image is as follows: Figure 2 As shown, the catalyst exhibits a hollow nanotube structure with uniformly distributed nanoneedle-like structures on its surface, with an average diameter of 1.52 μm. The activity of this catalyst in catalyzing the combustion of soot particles is shown in Table 1.

[0050] Example 5

[0051] Preparation of K 0.21 Mn 0.7 Ce 0.3 O δ Nanotube-structured catalysts

[0052] 0.3917 g of potassium acetate, 3.2611 g of manganese acetate tetrahydrate, and 2.4761 g of cerium nitrate hexahydrate were dissolved in a mixed solution of 8 mL ethanol and 2 mL water. After obtaining a homogeneous and transparent solution, 1.9 g of polyvinylpyrrolidone (Kw = 1300000) was dissolved in the above solution. The mixture was magnetically stirred for 30 min in a water bath at 55 °C to obtain a homogeneous sol-like precursor. After sonication for 10 min, the precursor was transferred to a medical syringe. A commercial cotton candy machine was used, and the speed was adjusted to 6000 rpm at room temperature. The precursor sol from the medical syringe was slowly and uniformly pushed into the rotor. Under centrifugal force, the precursor fibers were ejected from a small hole on the side of the rotor and collected with a collecting rod at a distance of 13.5 cm from the rotor. The collected fibers were dried at 80℃ for 12 hours, then calcined in a muffle furnace under air atmosphere. The temperature was increased from room temperature to 300℃ at a rate of 2℃ / min. After calcination for 1 hour, the temperature was increased to 550℃ over 20 minutes, and then calcined at 550℃ for 6 hours before being cooled to room temperature to obtain K. 0.21 Mn 0.7 Ce 0.3 O δ Nanotube-structured metal oxide catalysts.

[0053] K 0.21 Mn 0.7 Ce 0.3 O δ XRD pattern of hollow nanotube catalyst as shown in Figure Figure 1 As shown in the figure, the catalyst exhibits obvious CeO2 and crypto-potassium manganese oxide-type K2O. 2-x Mn8O 16 Characteristic diffraction peaks of the crystal form. Its SEM image is as follows: Figure 2 As shown, the catalyst exhibits a hollow nanotube structure with uniformly distributed nanoneedle-like structures on its surface, with an average diameter of 1.92 μm. The activity of this catalyst in catalyzing the combustion of soot particles is shown in Table 1.

[0054] Example 6

[0055] Preparation of K 0.27 Mn 0.9 Ce 0.1 O δ Nanotube-structured catalysts

[0056] 0.4799 g of potassium acetate, 3.9948 g of manganese acetate tetrahydrate, and 0.7864 g of cerium nitrate hexahydrate were dissolved in a mixed solution of 8 mL ethanol and 2 mL water. After obtaining a homogeneous and transparent solution, 2.0 g of polyvinylpyrrolidone (Kw = 1300000) was dissolved in the above solution. The mixture was magnetically stirred for 30 min in a water bath at 55 °C to obtain a homogeneous sol-like precursor. After sonication for 10 min, the precursor was transferred to a medical syringe. A commercial cotton candy machine was used, and the speed was adjusted to 6000 rpm at room temperature. The precursor sol from the medical syringe was slowly and uniformly pushed into the rotor. Under centrifugal force, the precursor fibers were ejected from a small hole on the side of the rotor and collected with a collecting rod at a distance of 13.5 cm from the rotor. The collected fibers were dried at 80℃ for 12 hours, then calcined in a muffle furnace under air atmosphere. The temperature was increased from room temperature to 300℃ at a rate of 2℃ / min. After calcination for 1 hour, the temperature was increased to 550℃ over 20 minutes, and then calcined at 550℃ for 6 hours before being cooled to room temperature to obtain K. 0.27 Mn 0.9 Ce 0.1 O δ Nanotube-structured metal oxide catalysts.

[0057] K 0.27 Mn 0.9 Ce 0.1 O δ XRD pattern of hollow nanotube catalyst as shown in Figure Figure 1 As shown in the figure, the catalyst exhibits obvious CeO2 and crypto-potassium manganese oxide-type K2O. 2-x Mn8O 16 Characteristic diffraction peaks of the crystal form. Its SEM image is as follows: Figure 2 As shown, the catalyst exhibits a hollow nanotube structure with uniformly distributed nanoneedle-like structures on its surface, with an average diameter of 1.93 μm. The activity of this catalyst in catalyzing the combustion of soot particles is shown in Table 1.

[0058] Table 1 Performance of Nanotube-structured Single Metal Oxide Catalysts in Catalytic Combustion of Carbon Particles

[0059]

[0060] Other embodiments of the invention will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of the invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of the invention are indicated by the claims.

Claims

1. A cerium-regulated potassium-manganese composite metal oxide catalyst with a hollow nanotube structure, characterized in that, The catalyst is: K 0.15 Mn 0.5 Ce 0.5 O δ Nanotube-structured metal oxide catalysts or K 0.21 Mn 0.7 Ce 0.3 O δ Nanotube-structured metal oxide catalysts or K 0.27 Mn 0.9 Ce 0.1 O δ Nanotube-structured metal oxide catalysts; The K 0.15 Mn 0.5 Ce 0.5 O δ The nanotube-structured metal oxide catalyst exhibits hollow nanotubes with uniformly distributed nanoneedle structures on its surface, with an average diameter of 1.52 μm; it possesses CeO2 and crypto-potassium manganese oxide-type K... 2-x Mn8O 16 Characteristic diffraction peaks of the crystal form; The K 0.21 Mn 0.7 Ce 0.3 O δ The nanotube-structured metal oxide catalyst exhibits hollow nanotubes with uniformly distributed nanoneedle structures on its surface, with an average diameter of 1.92 μm. It possesses CeO2 and crypto-potassium manganese oxide-type K+. 2-x Mn8O 16 Characteristic diffraction peaks of the crystal form; The K 0.27 Mn 0.9 Ce 0.1 O δ The nanotube-structured metal oxide catalyst exhibits hollow nanotubes with uniformly distributed nanoneedle structures on its surface, with an average diameter of 1.93 μm. It possesses CeO2 and crypto-potassium manganese oxide-type K+. 2-x Mn8O 16 Characteristic diffraction peaks of the crystal form.

2. A method for preparing the cerium-regulated potassium-manganese composite metal oxide catalyst as described in claim 1, characterized in that, include: Weigh out potassium acetate, manganese acetate tetrahydrate, and cerium nitrate hexahydrate according to the stoichiometric ratio, dissolve them in a mixed solution of ethanol and water, and after obtaining a clear solution, add polyvinylpyrrolidone. Then, heat the solution at 55°C. o After stirring in a water bath for 30 minutes, the homogeneous transparent sol-like precursor was collected. The sol-like precursor was collected and slowly injected into the centrifuge of a centrifugal spinning device. After solvent evaporation and drying at 6000 rpm, the precursor fibers were collected at a distance of 13.5 cm from the centrifuge. The collected fibers were dried in an oven at 80 °C for 24 h, and the dried fibers were calcined in a muffle furnace to obtain a hollow nanotube metal oxide catalyst. The muffle furnace is heated to 300°C at a heating rate of 2°C / min, maintained for 1 hour, then heated to 550°C within 20 minutes, and calcined at 550°C for 6 hours.

3. The method according to claim 2, characterized in that, The average molecular weight of the polyvinylpyrrolidone is 1,300,000, and K = 88-96.

4. The application of a cerium-regulated potassium-manganese composite metal oxide catalyst with a hollow nanotube structure as described in claim 1, characterized in that, The catalyst is used in the catalytic combustion reaction of soot particles in diesel engine exhaust.

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