Copper-manganese composite oxide catalyst and preparation method therefor and use thereof

Abstract

Provided are a copper-manganese composite oxide catalyst and a preparation method therefor and a use thereof. The catalyst contains copper oxide and manganese oxide, wherein the molar ratio of the copper element to the manganese element is Cu:Mn=2:1-1:5. A synthesis method for the catalyst comprises the steps of slurry forming, grinding, spray drying and heat treatment, and the catalyst can catalyze complete oxidative decomposition of hydrocarbons, especially propane, at a low temperature. The characteristics of simple synthesis method, easy industrial scale production and low production costs are achieved, high-cost noble metal components do not require to be used, and propane can be completely oxidized into carbon dioxide and water at the lowest temperature of 400°C, without generating other by-products.

Description

Copper-manganese composite oxide catalyst and its preparation method and application Technical Field

[0001] The present application relates to the field of catalysis, and more specifically to a copper-manganese composite oxide catalyst, a method for preparing the catalyst, and a method for catalytic combustion of hydrocarbon waste gas, especially propane waste gas, using the catalyst. Background Art

[0002] In recent years, with the country's increasingly stringent environmental protection requirements and stricter management of industrial exhaust emissions, various industries have developed different exhaust gas treatment technologies, such as thermal combustion, physical adsorption, chemical absorption, acid-base neutralization, and catalytic combustion. Catalytic combustion uses a catalyst to decompose organic waste into carbon dioxide and water at relatively low temperatures. It offers advantages such as high treatment efficiency and the absence of harmful byproducts. The most critical technical aspect of catalytic combustion technology is the development of catalysts that exhibit both low-temperature catalytic activity and long-term operational stability.

[0003] Common catalytic combustion catalysts mostly use catalysts based on precious metals, especially for hydrocarbon exhaust gases, because their molecular structure is relatively stable and difficult to oxidize, and only precious metal catalysts can decompose them at low temperatures. However, with the widespread use of automobile exhaust treatment devices with precious metals as active components worldwide, as well as the extensive use of precious metals in other fields, the prices of precious metals such as Pt, Pd, and Rh have increased significantly. The high cost has limited the promotion and application of precious metal catalysts. Therefore, finding alternatives to precious metal catalysts has always been a research hotspot. Transition metal oxide catalysts have attracted a lot of attention due to their low raw material costs. The transition metal oxides in this type of catalyst are in the form of single or combined forms, supplemented by various modification or loading processes. The preparation technology of the catalyst has a strong correlation with the performance of the catalyst. Technicians have developed preparation methods including precipitation method, hydrothermal method, solvent thermal method, solvent combustion method, solid grinding and mixing method, etc. However, these catalysts and their synthesis processes reported in the prior art all have insurmountable defects to varying degrees. The synthesis process is complex and the production process requirements are high, resulting in high production costs, complicated production operations, and the generation of large amounts of wastewater and exhaust gas during the production process, which brings additional process complexity and cost; the process repeatability is poor, resulting in performance fluctuations, further limiting its practical application; the catalytic performance of transition metal oxide catalysts is still not completely satisfactory, and the catalytic conversion efficiency of gaseous waste, especially alkane organic matter (such as propane) is insufficient. Other toxic and harmful byproducts (such as aldehyde byproducts) may also be generated during the conversion process.

[0004] In order to solve the above problems, many improvement measures have been proposed, such as further improving the catalyst composition formula or process conditions, but the degree of improvement is limited. Therefore, the art still hopes to develop an improved catalyst and synthesis process, using inexpensive transition metal oxide raw materials to synthesize a catalyst with excellent catalytic performance in a simple and low-cost manner, with good complete conversion ability for hydrocarbon organic pollutants, the conversion products are mainly harmless water and carbon dioxide, no other harmful by-products are generated, the process production has excellent repeatability, does not generate waste (such as wastewater or exhaust gas), and is easy to scale up for industrial production, thereby solving the above problems of the prior art.

[0005] Summary of the Invention

[0006] In response to the above problems, the inventors of the present application conducted in-depth research and successfully developed a copper-manganese composite oxide catalyst and a synthesis method thereof, thereby effectively solving the long-standing problem in the prior art that urgently needs to be solved.

[0007] The first aspect of the present application provides a copper-manganese composite oxide catalyst comprising copper, manganese, and oxygen, wherein the molar ratio of copper to manganese is Cu:Mn = 2:1 to 1:5. According to a preferred embodiment, the catalyst is composed of copper, manganese, and oxygen, and does not contain other metal elements, in particular, does not contain precious metal elements commonly used in the catalytic field, such as Pt, Pd, and Rh.

[0008] The second aspect of the present application provides a method for synthesizing the copper-manganese composite oxide catalyst of the present invention, the method comprising:

[0009] Step 1: Provide copper raw materials and manganese raw materials;

[0010] Step 2: Dispersing the copper raw material and the manganese raw material in a liquid medium to form a slurry;

[0011] Step 3: grinding the slurry;

[0012] Step 4: spray drying the ground slurry to obtain a precursor; and

[0013] Step 5: heat-treating the precursor.

[0014] A third aspect of the present application provides a method for catalytically oxidizing and decomposing hydrocarbons, comprising reacting the hydrocarbons with oxygen in the presence of the copper-manganese composite oxide catalyst of the present invention to produce carbon dioxide and water. According to a preferred embodiment, the method does not produce products other than carbon dioxide and water. According to another preferred embodiment, the method can be carried out at a temperature of at least 400°C. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The following paragraphs discuss various embodiments of the present application with reference to the accompanying drawings. However, it should be noted that the embodiments shown in the drawings and described below are merely preferred embodiments of the present application. The scope of protection of the present application is defined by the claims and is not limited to these preferred embodiments. Furthermore, for the purpose of clarity, the reactors and components shown in the drawings are not drawn to scale.

[0016] FIG1 shows an XRD characterization diagram of a catalyst according to one embodiment of the present application. DETAILED DESCRIPTION

[0017] "Range" disclosed herein is in the form of a lower limit and an upper limit. It can be one or more lower limits, and one or more upper limits, respectively. A given range is defined by selecting a lower limit and an upper limit. The selected lower limit and upper limit define the boundaries of a particular range. All ranges that can be defined in this way are inclusive and combinable, i.e., any lower limit can be combined with any upper limit to form a range. For example, a range of 60-120 and 80-110 is listed for a particular parameter, and it is understood that a range of 60-110 and 80-120 is also expected. In addition, if the minimum range values ​​listed are 1 and 2, and if the maximum range values ​​listed are 3, 4, and 5, then the following ranges can all be expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5.

[0018] In this application, unless otherwise specified, the numerical range "ab" is an abbreviation for any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" are listed herein, and "0-5" is merely an abbreviation for these numerical combinations.

[0019] In this application, unless otherwise specified, all embodiments and preferred embodiments mentioned herein can be combined with each other to form a new technical solution.

[0020] In this application, unless otherwise specified, all technical features and preferred features mentioned herein can be combined with each other to form a new technical solution.

[0021] In this application, unless otherwise specified, the term "comprising" as used herein may be open-ended or closed-ended. For example, "comprising" may mean that other components not listed may also be included, or only the listed components may be included.

[0022] The catalyst of the present application is a copper-manganese composite oxide catalyst, which can also be written as a "Cu-Mn-O catalyst". According to one embodiment of the present application, the copper element and the manganese element in the catalyst of the present application can exist in any suitable valence state, for example, the copper element can be +1 valence, +2 valence, or both valence states exist at the same time; the manganese element can be +1 valence, +2 valence, +3 valence, +4 valence, +5 valence, +6 valence, +7 valence, or a combination of one or more of the above valence states; and the oxygen element exists in a valence of -2, and its content is such that the negative valence provided by oxygen is balanced with the positive valence provided by the metal cation, so that the catalyst remains electrically neutral. According to an exemplary embodiment, the copper element and the manganese element in the catalyst of the present application can exist in one or more of the following forms: CuMn2O4 (for example, spinel crystal form), copper-manganese solid solution, copper oxide, cuprous oxide, manganese monoxide, manganese trioxide, manganese dioxide, manganese tetraoxide, manganese pentoxide, manganese trioxide. Preferably, the copper and manganese elements in the catalyst of the present application may be present in one or more of the following forms: CuO, MnO, MnO2, Mn3O4, copper-manganese spinel (CuMn2O4), copper-manganese solid solution, and any combination thereof. In the present invention, "copper-manganese solid solution" refers to a solid solution formed by copper oxide and manganese oxide.

[0023] According to one embodiment of the present application, the catalyst of the present application does not contain any other metal elements besides the aforementioned copper, manganese, and oxygen, and in particular does not contain any precious metal elements commonly used in the catalytic field, such as platinum, ruthenium, and rhodium. According to another embodiment of the present application, the catalyst of the present application is composed of copper, manganese, and oxygen, and does not contain any other elements.

[0024] According to one embodiment of the present application, in the catalyst of the present application, the molar ratio of copper element to manganese element is Cu:Mn=2:1 to 1:5, for example, 1:1 to 1:4, or 1:1.5 to 1:3, or 1:1.25 to 1:2.5, or 1:2, or the molar ratio of copper and manganese can be within the numerical range obtained by combining any two of the above end values.

[0025] According to one embodiment of the present application, based on the total weight of the catalyst of the present application, the content of copper (calculated as CuO) is 5-50 weight %, for example, 10-45 weight %, or 15-42 weight %, or 18-40 weight %, or 20-38 weight %, or 25-36 weight %, or 30-35 weight %, or 32-34.2 weight %, or can be within the numerical range obtained by combining any two of the above end values. According to another embodiment of the present application, based on the total weight of the catalyst of the present application, the content of manganese (calculated as Mn3O4) is 50-95 weight %, for example, 55-90 weight %, or 58-85 weight %, or 60-80 weight %, or 62-75 weight %, or 64-70 weight %, or 65-68 weight %, or can be within the numerical range obtained by combining any two of the above end values. It should be noted here that, when describing the respective weight contents of copper and manganese in the catalyst above, for the purpose of convenience, the weight content of copper is calculated in the form of CuO, and the weight content of manganese is calculated in the form of Mn3O4. However, this does not mean that copper and manganese exist in the catalyst in the form of CuO and Mn3O4, respectively. The possible existence forms of copper and manganese are as described above.

[0026] According to one embodiment of the present application, the catalyst of the present application is in the form of powder or fine particles. For example, the particle size of the catalyst can be 20 nanometers to 100 microns, for example, 40 nanometers to 50 microns, or 50 nanometers to 20 microns, or 80 nanometers to 10 microns, or 100 nanometers to 5 microns, or 120 nanometers to 2 microns, or 150 nanometers to 1 micron, or 100 nanometers to 800 nanometers, or 100 nanometers to 600 nanometers, or 100 nanometers to 500 nanometers, or 150 nanometers to 400 nanometers, or 180 nanometers to 300 nanometers, or 150-200 nanometers, or can be within the numerical range obtained by combining any two of the above end values.

[0027] According to some embodiments of the present application, the particle size of the catalyst, the raw material used to synthesize the catalyst, or the solid particles in the slurry can be measured by any suitable technique, such as microscopy, the Fresnel method, sedimentation, laser diffraction, etc. For example, according to a specific embodiment of the present application, the powder particle size described in the present application is measured by laser diffraction.

[0028] According to one embodiment of the present application, the copper-manganese composite oxide catalyst of the present application can be synthesized by a method comprising the following steps:

[0029] Step 1: Provide copper raw materials and manganese raw materials;

[0030] Step 2: Dispersing the copper raw material and the manganese raw material in a liquid medium to form a slurry;

[0031] Step 3: grinding the slurry;

[0032] Step 4: spray drying the ground slurry to obtain a precursor; and

[0033] Step 5: heat-treating the precursor.

[0034] According to one embodiment of the present application, in the step one, the copper raw material is one or more copper oxides, for example, the copper raw material can be selected from copper oxide, cuprous oxide, or a combination thereof. According to one embodiment of the present application, in the step one, the manganese raw material is one or more manganese oxides, for example, the manganese raw material can be selected from manganese monoxide, manganese trioxide, manganese dioxide, manganese tetraoxide, manganese pentoxide, manganese trioxide, or a combination thereof. According to one embodiment of the present application, various commercially available copper oxides and manganese oxides can be directly used as raw materials for preparing the catalyst of the present application. According to another embodiment of the present application, raw materials containing other metals are not used in the process of synthesizing the catalyst of this application, especially raw materials containing precious metals such as Pt, Pd, Ru, etc. are not used. According to a specific embodiment of the present application, the copper raw material is CuO and the manganese raw material is Mn3O4. According to one embodiment of the present application, the molar ratio of the copper element in the copper raw material to the manganese element in the manganese raw material is Cu:Mn=2:1 to 1:5, for example, 1:1 to 1:4, or 1:1.5 to 1:3, or 1:1.25 to 1:2.5, or 1:2, or the molar ratio of copper to manganese can be within the numerical range obtained by combining any two of the above end values.

[0035] According to one embodiment of the present application, the copper raw material and the manganese raw material are dispersed in a liquid medium to form a stable slurry. According to one embodiment of the present application, the liquid medium can be: (i) water; (ii) an organic solvent comprising one or more of the following: methanol, ethanol, isopropanol, benzene, toluene, xylene, pentane, hexane, octane, cyclohexane, cyclohexanone, toluene cyclohexanone, chlorobenzene, dichlorobenzene, dichloromethane, ethyl ether, methyl ether, methyl ethyl ether, propylene oxide, methyl acetate, ethyl acetate, propyl acetate, acetone, methyl butyl ketone, methyl isobutyl ketone, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, etc., acetonitrile, pyridine, phenol, styrene, perchloroethylene, trichloroethylene, ethylene glycol ether, triethanolamine; or (iii) a mixture of water and one or more of the organic solvents. According to a preferred embodiment of the present application, the liquid medium is an aqueous liquid medium, more preferably the liquid medium is pure water, for example, tap water, distilled water, double distilled water, deionized water, etc., preferably distilled water. According to some embodiments of the present application, based on the total weight of the slurry, the solid content of the slurry [(total weight of copper oxide and manganese oxide) ÷ total weight of slurry × 100%] can be 15-50% by weight, for example, 18-45% by weight, or 20-42% by weight, or 22-40% by weight, or 25-28% by weight, or can be within the numerical range obtained by combining any two of the above end values.

[0036] The copper raw material and the manganese raw material can be dispersed in a liquid medium to form the slurry using any conventional dispersion technology in the chemical industry, and non-limiting examples of the dispersion technology for the synthetic slurry can include a magnetic stirrer, a paddle stirrer, and various dispersers. According to one embodiment of the present application, a high-speed disperser equipped with a dispersion disc can be used to prepare the slurry of the present application. The design and structure of the high-speed disperser equipped with a dispersion disc are known in the art, wherein one or more (preferably two or more) dispersion discs are installed on the main shaft of the high-speed disperser, and when the main shaft of the disperser runs at high speed, the upper and lower parts of the dispersion disc are in a rotating state, and a turbulent zone is formed at the edge. The upper and lower serrations of the dispersion disc shear, impact, crush, and disperse the copper raw material, manganese raw material, and liquid medium at high speed, so as to achieve a state of rapid mixing, dissolution, dispersion, and refinement. According to one embodiment of the present application, the dispersion disk can be a circular or annular disk-shaped component made of metal (e.g., steel, aluminum alloy, ceramic material, etc.), and its interior or edge portion can be provided with various serrated, wavy, circular, elliptical, rectangular, polygonal or any other shaped perforations, notches, edge protrusions or depressions, protrusions or depressions above or below the dispersion disk, and other geometric shapes as needed. The specific types and various designs of dispersion disks are known in the art, and may include, for example, flat disc serrated dispersion disks, three-paddle dispersion disks, dish dispersion disks, multi-tooth dispersion disks, three-tooth dispersion disks, single-sided tooth dispersion disks, double-sided tooth dispersion disks, peripheral tooth dispersion disks, etc.

[0037] According to one embodiment of the application, in step three, the solid particles in the slurry are ground to a particle size of less than 300 nanometers. In this step three, the grinding can be carried out using any technology and equipment suitable for grinding the solid particles in the slurry known in the chemical industry. For example, various grinders or sand mills known in the art can be used, such as vertical sand mills, three-roll grinders, horizontal grinders, basket grinders, planetary grinders, etc., disc grinders, rotary shaft grinders, etc. For example, a suitable sand mill can be used to grind the solid particles in the slurry under the condition of grinding beads or grinding balls. According to one embodiment of the application, the grinding lasts for a specific time, such as 30 minutes to 24 hours, such as 1-16 hours, or 1.5-12 hours, or 2-6 hours, or 2.5-4 hours, or 3 hours, or the duration of the grinding can be within the numerical range obtained by combining any two of the above-mentioned end values. According to one embodiment of the present application, after grinding, the particle size of the solid particles in the slurry can be less than 300 nanometers, for example, 10-300 nanometers, or ≤290 nanometers, or ≤280 nanometers, or ≤260 nanometers, or ≤250 nanometers, or ≤220 nanometers, or ≤200 nanometers, or ≤190 nanometers, or ≤150 nanometers, or ≤130 nanometers, or 50-300 nanometers, or 80-300 nanometers, or 100-300 nanometers, or 120-300 nanometers, or the particle size range can be within the numerical range obtained by combining any two of the above end values.

[0038] According to one embodiment of the present application, the ground slurry is spray-dried to obtain a precursor. The spray drying can be performed using a spray dryer known in the art. In the spray dryer, the slurry prepared in step 3 is sprayed into a drying chamber in a mist form; at the same time, air is filtered and heated before evenly entering the drying chamber; the misted slurry droplets come into contact with the hot air in the drying chamber of the spray dryer, causing the droplets to dry, thereby obtaining a precursor in a fine particle state. The particle size of the precursor is basically as described above, and the particle size can be less than 300 nanometers, for example, 10-300 nanometers, or ≤290 nanometers, or ≤280 nanometers, or ≤260 nanometers, or ≤250 nanometers, or ≤220 nanometers, or ≤200 nanometers, or ≤190 nanometers, or ≤150 nanometers, or ≤130 nanometers, or 50-300 nanometers, or 80-300 nanometers, or 100-300 nanometers, or 120-300 nanometers, or the particle size range can be within the numerical range obtained by combining any two of the above end values. According to one embodiment of the present application, the air inlet temperature (i.e., the temperature of the hot air flowing into the drying chamber) during spray drying is 200-350°C, for example, 220-320°C, or 250-300°C, or 270-290°C, or within the numerical range obtained by combining any two of the above end values; the air outlet temperature (i.e., the temperature of the hot air leaving the drying chamber) is 80-150°C, for example, 100-120°C, or within the numerical range obtained by combining any two of the above end values.

[0039] According to one embodiment of the present application, in step five, the precursor prepared in step four is heat-treated to obtain the catalyst of the present application. The heat treatment can be carried out in any suitable heating equipment, for example, it can be carried out in a heating oven, a muffle furnace, a tube furnace and the like. The heat treatment can be carried out in any suitable atmosphere, such as an air atmosphere, an oxidizing atmosphere (such as an oxygen atmosphere), an inert atmosphere (such as a nitrogen atmosphere, an argon atmosphere), a vacuum atmosphere, etc. According to one embodiment of the present application, the heat treatment is carried out in an air atmosphere.

[0040] According to one embodiment of the present application, the heat treatment is carried out at a temperature of 400-600°C, for example, 450-580°C, or 480-560°C, or 500-550°C, or 550-580°C, or 520-540°C, or the temperature of the heat treatment can be within the numerical range obtained by combining any two of the above end values. The duration of the heat treatment can be 1-24 hours, for example, 2-20 hours, or 3-16 hours, or 4-12 hours, or 4-8 hours, or 4-6 hours, or the duration of the heat treatment can be within the numerical range obtained by combining any two of the above end values.

[0041] According to one embodiment of the present application, the catalyst of the present invention can be used to catalytically oxidize and decompose hydrocarbons, so that the hydrocarbons react with oxygen to generate carbon dioxide and water.

[0042] According to an embodiment of the application, the hydrocarbons can include alkane, alkene or aromatic hydrocarbons of straight chain or branched chain.Preferably, the hydrocarbons can for example include one to sixteen carbon atoms (i.e. C1-C16), for example, can include one to twelve carbon atoms, or can include one to eight carbon atoms, or can include one to six carbon atoms, or can include one to four carbon atoms, or can include one to three carbon atoms.For example, the example of the hydrocarbons can include methane, ethane, propane, butane, ethene, propylene, cyclohexane, benzene, toluene etc.According to an embodiment of the application, the catalytic oxidation reaction can not generate the product except carbon dioxide and water.

[0043] According to one embodiment of the present application, the catalytic oxidative decomposition of alkanes is carried out in the presence of the catalyst of the present invention at a temperature of at least 400° C. For example, the catalytic oxidative decomposition of alkanes can achieve an alkane conversion rate of ≥95% at a temperature of ≤400° C., or an alkane conversion rate of ≥95% at a temperature of ≤390° C., or an alkane conversion rate of ≥95% at a temperature of ≤380° C., or an alkane conversion rate of ≥95% at a temperature of ≤360° C., or an alkane conversion rate of ≥95% at a temperature of ≤350° C., or an alkane conversion rate of ≥95% at a temperature of ≤340° C., or an alkane conversion rate of ≥95% at a temperature of ≤330° C., or an alkane conversion rate of ≥95% at a temperature of ≤320° C., or an alkane conversion rate of ≥95% at a temperature as low as 310° C.

[0044] According to one embodiment of the present application, the lowest temperature at which the catalyst can achieve different conversion rates of hydrocarbons (such as propane) can be used to characterize the reactivity of the catalyst, and the conversion rate of the hydrocarbons can be calculated using the following formula:

[0045] Conversion rate of hydrocarbons (%) = [(amount of hydrocarbons before reaction - amount of hydrocarbons after reaction) / amount of hydrocarbons before reaction] × 100%

[0046] According to one embodiment of the present application, propane is used as an exemplary hydrocarbon to characterize the catalytic performance of the catalyst of the present application. In this case, the conversion rate of propane can be calculated using the following formula:

[0047] Conversion rate of propane (%) = [(amount of propane before reaction - amount of propane after reaction) / amount of propane before reaction] × 100%

[0048] According to one embodiment of the present application, the catalytic activity of the catalyst can be represented by the lowest temperature T10 (called the initial reaction temperature), T50 (called the characteristic reaction temperature) and T95 (called the complete conversion temperature) at which the conversion rate of alkanes (such as propane) can reach 10%, 50% and 95%. The lower the temperature value, the better the activity of the catalyst. In addition, ΔT (ΔT = T95-T10) is also related to the performance of the catalyst. The smaller the value, the more suitable the performance of the catalyst for practical application. According to one embodiment of the present application, when the conversion rate of hydrocarbons (such as propane) reaches 95%, it is considered that the hydrocarbons have been completely converted, and therefore T95 is referred to as the complete conversion temperature.

[0049] According to one embodiment of the present application, hydrocarbons can be mixed with an oxygen-containing gas (such as air or pure oxygen) to form a reaction mixture, and the reaction mixture is allowed to flow through a reactor equipped with a catalyst of the present invention at a reaction temperature, so that hydrocarbons (such as propane) react with oxygen under the catalytic action of the catalyst of the present invention, so that hydrocarbons (such as propane) are oxidized and decomposed to produce products CO2 and water, and substantially no other by-products are generated, preferably no other by-products are generated at all. The temperature of the hydrocarbon catalytic oxidation decomposition reaction is as described above, and can be ≤400°C, or ≤390°C, or ≤380°C, or ≤360°C, or ≤350°C, or ≤340°C, or ≤330°C, or ≤320°C, or ≥310°C. The temperature of the hydrocarbon catalytic oxidation decomposition reaction can be within the numerical range obtained by combining any two of the above end values.

[0050] The present application is described below in the form of specific examples for the purpose of providing a better understanding of the present application. It should be understood that these examples are merely illustrative and non-restrictive. The reagents used in the examples are all commercially available unless otherwise specified. The methods and conditions used in the examples are conventional methods and conditions unless otherwise specified.

[0051] Example

[0052] In the following examples, the catalyst of the present invention was synthesized and its catalytic activity was investigated using propane as an example. However, it should be noted that the following examples are merely specific examples of the present application, and the technical features of the present application are not limited thereto. Any simple variations, equivalent substitutions, or other modifications based on the present application that solve essentially the same technical problems and achieve essentially the same technical effects are encompassed within the scope of protection of the present application.

[0053] The raw materials used in the following examples were all commercially purchased analytically pure samples and were used directly without further purification or treatment.

[0054] Example 1

[0055] In this Example 1, the catalyst of the present application was synthesized by the following steps. 79.5 grams of CuO and 152.7 grams of Mn3O4 were weighed and poured into a stainless steel barrel. 600 grams of distilled water was then added thereto. A high-speed disperser equipped with a dispersion disc on the main shaft was used to disperse the mixture for 2 hours to form a stable slurry. The resulting slurry was then added to a Langling NT-V1 sand mill. Grinding beads were added to the sand mill and the machine was started for 3 hours of grinding. The solid particle size after grinding, as measured by laser diffraction, was 250 nanometers. The ground slurry was transported to an Okawahara OADB-8 spray dryer and dried by spray drying. The inlet air temperature in the spray dryer was 250°C and the outlet air temperature was 100°C. The dried precursor was placed in a muffle furnace and heat-treated at 550°C for 4 hours in an air atmosphere. It was then naturally cooled to obtain the catalyst of the present invention.

[0056] The XRD spectrum of the catalyst prepared in Example 1 is shown in FIG1 , and the results show that the crystal phase in the prepared catalyst is mainly a spinel crystal phase.

[0057] Example 2

[0058] In Example 2, the same equipment as in Example 1 was used to synthesize the catalyst of the present invention.

[0059] Specifically, in Example 2, 79.5 g of CuO and 152.7 g of Mn3O4 were weighed and poured into a stainless steel barrel. 600 g of distilled water was then added thereto. A high-speed disperser equipped with a dispersion disc on the main shaft was used to disperse the mixture for 2 hours to form a stable slurry. The resulting slurry was then added to a sand mill, grinding beads were added to the sand mill, and the machine was started for 5 hours of grinding. The solid particle size after grinding, measured by laser diffraction, was 183 nm. The ground slurry was transported to a spray dryer and dried by spray drying. The inlet air temperature in the spray dryer was 250°C and the outlet air temperature was 100°C. The dried precursor was placed in a muffle furnace and heat treated at 550°C for 4 hours in an air atmosphere. It was then naturally cooled to obtain the catalyst of the present invention.

[0060] Example 3

[0061] In Example 3, the same equipment as in Example 1 was used to synthesize the catalyst of the present invention.

[0062] Specifically, in Example 3, 79.5 g of CuO and 152.7 g of Mn3O4 were weighed and poured into a stainless steel barrel. 600 g of distilled water was then added thereto. A high-speed disperser equipped with a dispersion disc on the main shaft was used to disperse the mixture for 2 hours to form a stable slurry. The resulting slurry was then added to a sand mill, grinding beads were added to the sand mill, and the machine was started for 8 hours of grinding. The solid particle size after grinding, measured by laser diffraction, was 122 nm. The ground slurry was transported to a spray dryer and dried by spray drying. The inlet air temperature in the spray dryer was 320°C and the outlet air temperature was 120°C. The dried precursor was placed in a muffle furnace and heat treated at 500°C for 4 hours in an air atmosphere. It was then naturally cooled to obtain the catalyst of the present invention.

[0063] Example 4

[0064] In Example 4, the same equipment as in Example 1 was used to synthesize the catalyst of the present invention.

[0065] Specifically, in Example 4, 79.5 g of CuO and 152.7 g of Mn3O4 were weighed and poured into a stainless steel barrel. 600 g of distilled water was then added thereto. A high-speed disperser equipped with a dispersion disc on the main shaft was used to disperse the mixture for 2 hours to form a stable slurry. The resulting slurry was then added to a sand mill, grinding beads were added to the sand mill, and the machine was started for 8 hours of grinding. The solid particle size after grinding, measured by laser diffraction, was 122 nm. The ground slurry was transported to a spray dryer and dried by spray drying. The inlet air temperature in the spray dryer was 350°C and the outlet air temperature was 100°C. The dried precursor was placed in a muffle furnace and heat treated at 580°C for 8 hours in an air atmosphere. It was then naturally cooled to obtain the catalyst of the present invention.

[0066] Comparative Example 1

[0067] In Comparative Example 1, the same equipment as in Example 1 was used to synthesize a comparative catalyst. However, in Comparative Example 1, the slurry was not ground but directly spray-dried.

[0068] Specifically, in Comparative Example 1, 79.5 g of CuO and 152.7 g of Mn₃O₄ were weighed and poured into a stainless steel barrel. 600 g of distilled water was then added. The mixture was dispersed for 2 hours using a high-speed disperser equipped with a dispersion disc on its main shaft to form a stable slurry. The resulting slurry was then transferred to a spray dryer and dried by spray drying at an inlet air temperature of 350°C and an outlet air temperature of 100°C. The dried precursor was placed in a muffle furnace and heat treated at 580°C for 8 hours in an air atmosphere. The mixture was then naturally cooled to obtain the catalyst of Comparative Example 1.

[0069] Comparative Example 2

[0070] In this Comparative Example 2, a comparative catalyst was synthesized using the same equipment as in Example 1, but only Mn 3 O 4 raw material was used without using CuO.

[0071] Specifically, in Comparative Example 2, 152.7 g of Mn3O4 was weighed and poured into a stainless steel barrel. 600 g of distilled water was then added. A high-speed disperser equipped with a dispersion disc on the main shaft was used to disperse the mixture for 2 hours to form a stable slurry. The resulting slurry was then added to a sand mill, grinding beads were added to the sand mill, and the machine was started for 8 hours of grinding. The solid particle size after grinding, measured by laser diffraction, was 134 nm. The ground slurry was transferred to a spray dryer and dried by spray drying. The inlet air temperature in the spray dryer was 350°C and the outlet air temperature was 100°C. The dried precursor was placed in a muffle furnace and heat treated at 580°C for 8 hours in an air atmosphere. It was then naturally cooled to obtain the catalyst of Comparative Example 2.

[0072] Comparative Example 3

[0073] In Comparative Example 3, a comparative catalyst was synthesized using the same equipment as in Example 1, but using only CuO raw material without using Mn3O4.

[0074] Specifically, in Comparative Example 2, 79.5 g of CuO was weighed and poured into a stainless steel barrel. 600 g of distilled water was then added. A high-speed disperser equipped with a dispersion disc on the main shaft was used to disperse the mixture for 2 hours to form a stable slurry. The resulting slurry was then added to a sand mill, grinding beads were added to the sand mill, and the machine was started for 8 hours of grinding. The solid particle size after grinding, measured by laser diffraction, was 89 nm. The ground slurry was transferred to a spray dryer and dried by spray drying. The inlet air temperature in the spray dryer was 350°C and the outlet air temperature was 100°C. The dried precursor was placed in a muffle furnace and heat treated at 580°C for 8 hours in an air atmosphere. It was then naturally cooled to obtain the catalyst of Comparative Example 3.

[0075] Example 5: Catalyst Performance Characterization

[0076] In this example, the catalysts of Examples 1-4 and Comparative Examples 1-3 were used to carry out the catalytic oxidation decomposition of propane. Specifically, a quartz tube with an inner diameter of 6 mm was used as a reactor. 100 mg of the catalyst was loaded into the tube. The reaction section of the tube was inserted into a tube furnace. After heating to the target reaction temperature, a mixture of propane and air was introduced into the tube. The total space velocity of the mixture was 60,000 h / min.-1 The propane concentration was 3000 ppm. The tail gas exiting the quartz tube was analyzed online using gas chromatography. For each catalyst, its T10, T50, and T95 for propane were measured as described in this specification, and ΔT was calculated. The results are summarized in Table 1 below. Product types were also analyzed based on signal peaks in the gas chromatogram.

[0077] Table 1: Test results of Examples 1-4 and Comparative Examples 1-3, where the values ​​are in °C

[0078] The above experimental results demonstrate that the copper-manganese composite oxide catalysts prepared in Examples 1-4 of the present application exhibit excellent catalytic activity, significantly outperforming the catalysts in Comparative Examples 1-3. The catalyst in Example 3 exhibited the best performance, achieving a propane conversion rate of 95% at 310°C, demonstrating excellent practical application value. Furthermore, it can be seen that Examples 1-4 achieve excellent catalytic performance without requiring prolonged grinding of the particles or requiring significant particle size reduction.

[0079] Furthermore, based on gas chromatographic signal peaks, it can be determined that the products of the propane catalytic oxidation reaction in Examples 1-4 of the present application are solely CO and water, with no other byproducts generated. In contrast, in Comparative Examples 1-3, small amounts of CO and acrolein were observed as byproducts. CO and acrolein are produced as incomplete propane oxidation products and are harmful to the environment.

[0080] Example 6

[0081] In Example 6, the applicant repeated the synthesis steps of Example 1 ten times to synthesize ten catalyst samples, and the performance of these catalyst samples was tested according to the steps of Example 5. The results showed that the T10, T50, T95, and ΔT values ​​of all ten catalyst samples were essentially the same as those of the catalyst in Example 1. This demonstrates that the catalyst synthesis process of the present application has excellent reproducibility, and each batch of catalyst synthesized can demonstrate stable and excellent catalytic performance, with no performance fluctuations between different batches.

[0082] The catalyst of this application has at least the following advantages:

[0083] The catalyst and preparation method of the present invention do not use precious metals, are low-cost, and have a simple synthesis method. Compared with the synthesis methods of the prior art, the raw materials are cheap and readily available, no waste gas or wastewater is generated, the environmental cost is low, and it is easy to scale up for industrial production. The prepared catalyst has better activity than catalysts prepared by conventional precipitation methods, solvent combustion methods, and solid grinding methods, and has good process stability and product batch stability. In addition, compared with other non-precious metal catalysts in the prior art, the catalyst of the present invention can significantly reduce the ignition temperature and complete conversion temperature of propane catalytic combustion, and propane can be completely oxidized to carbon dioxide and water without generating other byproducts.

Claims

1. A copper-manganese composite oxide catalyst, comprising copper, manganese and oxygen, wherein the molar ratio of copper to manganese is Cu:Mn=2:1 to 1:

5.

2. The copper-manganese composite oxide catalyst according to claim 1, characterized in that The copper element and the manganese element in the catalyst exist separately or in combination in one or more states selected from the following: CuMn2O4 spinel, copper-manganese solid solution, copper oxide, cuprous oxide, manganese monoxide, manganese trioxide, manganese dioxide, manganese tetraoxide, manganese pentoxide, and manganese trioxide.

3. The copper-manganese composite oxide catalyst according to claim 1 or 2, characterized in that The catalyst is composed of copper, manganese and oxygen.

4. A method for synthesizing the copper-manganese composite oxide catalyst as claimed in any one of claims 1 to 3, the method comprising: Step 1: Provide copper raw materials and manganese raw materials; Step 2: dispersing the copper raw material and the manganese raw material in a liquid medium to form a slurry; Step 3: grinding the slurry; Step 4: spray drying the ground slurry to obtain a precursor; as well as Step five: heat-treating the precursor.

5. The method according to claim 4, characterized in that In step 1, the copper raw material is selected from cupric oxide, cuprous oxide, or a combination thereof; the manganese raw material is selected from manganese monoxide, manganese trioxide, manganese dioxide, manganese tetraoxide, manganese pentoxide, manganese trioxide, or a combination thereof; and the molar ratio of the copper element in the copper raw material to the manganese element in the manganese raw material is 2:1 to 1:

5.

6. The method according to claim 4, characterized in that In the step 2, the liquid medium is (i) water; (ii) an organic solvent comprising one or more of the following: methanol, ethanol, isopropanol, benzene, toluene, xylene, pentane, hexane, octane, cyclohexane, cyclohexanone, toluene cyclohexanone, chlorobenzene, dichlorobenzene, dichloromethane, ethyl ether, methyl ether, methyl ethyl ether, propylene oxide, methyl acetate, ethyl acetate, propyl acetate, acetone, methyl butyl ketone, methyl isobutyl ketone, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, etc., acetonitrile, pyridine, phenol, styrene, perchloroethylene, trichloroethylene, ethylene glycol ether, triethanolamine; or (iii) a mixture of water and one or more of the organic solvents; The solid content of the slurry is 15-50 wt % based on the total weight of the slurry.

7. The method according to claim 4, characterized in that In step three, the solid particles in the slurry are ground to a particle size less than 300 nanometers.

8. The method according to claim 4, characterized in that In step 4, the inlet air temperature of the spray drying is 200-350°C, and the outlet air temperature is 80-150°C; In step five, heat treatment is performed at a temperature of 400-600° C. for 1-24 hours.

9. A method for catalytically oxidizing and decomposing hydrocarbons, the method comprising reacting hydrocarbons with oxygen to produce carbon dioxide and water in the presence of a copper-manganese composite oxide catalyst as claimed in any one of claims 1 to 3.

10. The method according to claim 9, characterized in that The process does not generate products other than carbon dioxide and water; and the process can be carried out at a temperature as low as 400°C.

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