Copper-manganese bimetallic oxide catalyst, preparation method thereof and application of copper-manganese bimetallic oxide catalyst in treatment of volatile organic compound waste gas

Abstract

The invention provides a copper-manganese bimetallic oxide catalyst, a preparation method thereof and application of the copper-manganese bimetallic oxide catalyst in treatment of volatile organic compound waste gas. Wherein the crystal structure of the copper-manganese bimetallic oxide catalyst is a monoclinic copper oxide phase, and manganese metal is embedded into a monoclinic copper oxide phase lattice in an ion form. The prepared copper-manganese bimetallic oxide catalyst has excellent catalytic activity, water resistance and stability, can realize deep degradation of volatile organic compounds including alkanes, olefins and aromatic hydrocarbons, and is beneficial to low-cost and efficient removal of the volatile organic compounds in actual industrial tail gas.

Description

Technical Field

[0001] The present disclosure belongs to the field of environmental catalysis technology, and in particular relates to a copper-manganese bimetallic oxide catalyst, a preparation method and application thereof, and more specifically relates to a copper-manganese bimetallic oxide catalyst, a preparation method and application thereof in degrading volatile organic compounds. Background Art

[0002] With the rapid development of economy and industry, the emissions of environmental pollutants, especially volatile organic compounds (VOCs), have increased significantly.

[0003] Among VOC treatment technologies, catalytic oxidation has become a research hotspot due to its cost-effectiveness and high efficiency. Catalysts used for VOC degradation are primarily classified into two categories: precious metal catalysts and transition metal oxide catalysts. While precious metal catalysts possess superior catalytic activity, their high cost limits their widespread application. In contrast, transition metal oxide catalysts have attracted attention due to their excellent stability and low cost. However, the catalytic activity of transition metal oxides in VOC degradation still needs to be further improved to achieve cost-effective and efficient VOC disposal. Summary of the Invention

[0004] In view of this, the main purpose of the present disclosure is to provide a copper-manganese bimetallic oxide catalyst and a preparation method and application thereof, in order to at least partially solve at least one of the above-mentioned technical problems.

[0005] To achieve the above objectives, the technical solutions disclosed herein are as follows:

[0006] In one aspect of the present disclosure, a copper-manganese bimetallic oxide catalyst is provided, wherein:

[0007] The crystal structure of the copper-manganese bimetallic monoclinic copper oxide phase catalyst is a monoclinic copper oxide phase, and manganese metal is embedded in the monoclinic copper oxide phase lattice in the form of ions.

[0008] In another aspect of the present disclosure, a method for preparing a copper-manganese bimetallic oxide catalyst is provided, comprising:

[0009] Copper salt and manganese salt are mixed in water in proportion to form a mixed solution, an alkaline solution is added to adjust the pH value of the mixed solution, and a precipitate is obtained after heating;

[0010] calcining the precipitate to obtain a copper-manganese bimetallic oxide catalyst;

[0011] The molar ratio of the copper salt to the manganese salt is 2-5:1, the pH value of the alkaline solution is 9.5-11.5, and the calcination temperature of the calcination treatment is 200-400°C.

[0012] In yet another aspect of the present disclosure, there is provided a use of the copper-manganese bimetallic oxide catalyst in the degradation of volatile organic compounds.

[0013] According to an embodiment of the present disclosure, a copper-manganese bimetallic oxide catalyst having a crystal structure of a monoclinic copper oxide phase is provided. In this case, manganese metal is embedded in the monoclinic copper oxide phase lattice in the form of ions to form Cu-O-Mn sites. The Cu-O-Mn sites construct new electron transfer pathways inside the catalyst, promoting the rapid and efficient transfer of electrons inside the catalyst, thereby optimizing the electronic structure of the catalyst, increasing the rate of the catalytic reaction and the oxidation capacity of the active oxygen species in the catalyst. In addition, the Cu-O-Mn sites also promote the redox reaction, accelerate the migration of oxygen species inside the catalyst, and help form a faster and more stable Mars-van-Krevelen (MvK) cycle, so that the active oxygen species can reach the reaction site more quickly and participate in the catalytic reaction, further improving the catalytic efficiency of the catalyst. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 is a scanning electron microscope image of the copper-manganese bimetallic oxide catalyst in Example 1;

[0015] Figure 1a is a transmission electron microscope elemental mapping image of the copper-manganese bimetallic oxide catalyst in Example 1;

[0016] Figure 1b is the X-ray diffraction pattern of the copper-manganese bimetallic oxide catalyst in Example 1;

[0017] Figure 2a This is a graph showing the degradation efficiency of cyclohexane at different temperatures for the copper-manganese bimetallic oxide catalyst in Example 1;

[0018] Figure 2b This is a graph showing the degradation efficiency of the copper-manganese bimetallic oxide catalyst for benzene at different temperatures in Example 1;

[0019] Figure 2c This is a graph showing the degradation efficiency of the copper-manganese bimetallic oxide catalyst for 1,3-butadiene at different temperatures in Example 1;

[0020] Figure 2d 1 is a graph showing the degradation efficiency of cyclohexane by the copper-manganese bimetallic oxide catalyst in Example 1 under dry conditions and different relative humidity conditions;

[0021] Figure 2e This is a graph showing the degradation efficiency of cyclohexane by the copper-manganese bimetallic oxide catalyst in Example 1 at 260°C within 48 hours.

[0022] Figure 3ais the X-ray diffraction pattern of the copper-manganese bimetallic oxide catalyst in Example 2;

[0023] Figure 3b is a graph showing the degradation efficiency of cyclohexane at different temperatures for the copper-manganese bimetallic oxide catalyst in Example 2;

[0024] Figure 4a This is the X-ray diffraction pattern of the copper-manganese bimetallic oxide catalyst in Comparative Example 1;

[0025] Figure 4b This is a graph showing the degradation efficiency of cyclohexane at different temperatures using the copper-manganese bimetallic oxide catalyst in Comparative Example 1;

[0026] Figure 5a This is the X-ray diffraction pattern of the copper-manganese bimetallic oxide catalyst in Comparative Example 2;

[0027] Figure 5b This is a graph showing the degradation efficiency of cyclohexane at different temperatures using the copper-manganese bimetallic oxide catalyst in Comparative Example 2;

[0028] Figure 6 This is a graph showing the degradation efficiency of cyclohexane by the copper single metal oxide catalyst at different temperatures in Comparative Example 3;

[0029] Figure 7 This is a graph showing the degradation efficiency of cyclohexane by the manganese single metal oxide catalyst in Comparative Example 4 at different temperatures;

[0030] Figure 8a This is the X-ray diffraction pattern of the copper-manganese bimetallic oxide catalyst in Comparative Example 5;

[0031] Figure 8b This is a graph showing the degradation efficiency of cyclohexane at different temperatures using the copper-manganese bimetallic oxide catalyst in Comparative Example 5;

[0032] Figure 9 This is the X-ray diffraction pattern of the copper-manganese bimetallic oxide catalyst in Comparative Example 6.

[0033] Figure 10 1 is a distribution diagram of by-products during the degradation of cyclohexane by the catalyst in Example 1 and Comparative Examples 1, 3, and 4;

[0034] Figure 11 Attached are the oxygen temperature-programmed desorption diagrams of the catalysts in Example 1, Example 2, Comparative Example 1, Comparative Example 2, Comparative Example 3 and Comparative Example 4. DETAILED DESCRIPTION

[0035] In order to make the objectives, technical solutions and advantages of the present disclosure more clearly understood, the present disclosure is further described in detail below in conjunction with specific embodiments.

[0036] The endpoints of the ranges and any values ​​disclosed in this disclosure are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be considered to be specifically disclosed in this disclosure.

[0037] The terms used herein are only for describing specific embodiments and are not intended to limit the present disclosure. The terms "comprise," "include," etc. used herein indicate the presence of the features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.

[0038] With the rapid development of the economy and industry, emissions of environmental pollutants, particularly volatile organic compounds (VOCs), have increased significantly. VOCs are organic compounds with boiling points between 50°C and 260°C at standard atmospheric pressure. As important precursors to secondary aerosols, ozone, and photochemical smog, they pose a significant threat to air quality and human health. Catalytic oxidation technology has become an effective approach for VOC removal due to its cost-effectiveness and high efficiency. However, current transition metal oxide catalysts still have limited catalytic activity, hindering their effectiveness in practical applications. Therefore, optimizing catalysts to enhance their catalytic activity and stability has become an urgent challenge to improve VOC degradation.

[0039] In the process of realizing the concept of the present disclosure, it was found that the copper-manganese bimetallic oxide catalyst is suitable for the catalytic degradation of volatile organic compounds due to its flexible valence characteristics between copper ions and manganese ions and good economic benefits. The copper-manganese bimetallic oxide catalyst has various types of crystal structures, including monoclinic copper oxide (CuO) phase, tetragonal manganese tetraoxide (Mn3O4) phase, cubic copper-manganese spinel (Cu 1.5 Mn 1.5 Further research found that different crystal structures have different effects on catalyst performance: copper-manganese bimetallic oxide catalysts with monoclinic copper oxide (CuO) phase showed higher catalytic activity, while those containing tetragonal manganese tetraoxide (Mn3O4) phase and cubic copper-manganese spinel (Cu 1.5 Mn 1.5O4) phase, the catalytic performance of the catalyst is relatively reduced. Therefore, the present invention regulates the preparation method of the copper-manganese bimetallic oxide catalyst so that it presents a monoclinic copper oxide phase crystal structure, which not only improves the stability and activity of the catalyst, but also provides a structural basis for the embedding of manganese metal ions. It is possible to embed manganese ions into the monoclinic copper oxide phase lattice to form Cu-O-Mn sites, thereby optimizing the electronic structure of the catalyst and improving the stability and activity of active oxygen species on the catalyst surface. In addition, the formation of Cu-O-Mn sites also enhances the migration ability of oxygen species within the catalyst, so that the copper-manganese bimetallic oxide catalyst exhibits excellent deep degradation ability when catalytically degrading volatile organic pollutants.

[0040] According to an embodiment of one aspect of the present disclosure, a copper-manganese bimetallic oxide catalyst is proposed, wherein:

[0041] The crystal structure of the copper-manganese bimetallic oxide catalyst is a monoclinic copper oxide phase, and manganese metal is embedded in the monoclinic copper oxide phase lattice in the form of ions.

[0042] According to an embodiment of the present disclosure, a copper-manganese bimetallic oxide catalyst having a monoclinic copper oxide phase crystal structure is provided, wherein manganese metal is embedded in the monoclinic copper oxide phase lattice in ionic form, forming Cu-O-Mn sites. The Cu-O-Mn sites establish new electron transfer pathways within the catalyst, promoting rapid and efficient electron transfer within the catalyst, thereby optimizing the electronic structure of the catalyst and improving the rate and effectiveness of the catalytic reaction. Secondly, the presence of the Cu-O-Mn sites enables active oxygen species to maintain a highly active state on the catalyst surface for a longer period of time, helping to stabilize the active oxygen species. In addition, due to the variable valence characteristics of manganese and copper ions, the Cu-O-Mn sites also promote the redox reaction, accelerate the migration of oxygen species within the catalyst, and help form a faster and more stable Mars-van-Krevelen (MvK) cycle, allowing active oxygen species to reach the reaction sites more quickly and participate in the catalytic reaction, further improving the catalytic efficiency of the catalyst.

[0043] According to an embodiment of the present disclosure, the copper-manganese bimetallic oxide catalyst morphology includes a nanosheet structure. The nanosheet structure has a large specific surface area, which helps increase the number of active sites, thereby improving the catalytic activity of the catalyst.

[0044] According to another embodiment of the present disclosure, a method for preparing the copper-manganese bimetallic oxide catalyst is provided, comprising:

[0045] A copper salt and a manganese salt are mixed in water in proportion to form a mixed solution, an alkaline solution is added to adjust the pH value of the mixed solution, and a precipitate is obtained after heating; the precipitate is calcined to obtain a copper-manganese bimetallic oxide catalyst; wherein the molar ratio of the copper salt to the manganese salt is 2-5:1, the pH value of the alkaline solution is 9.5-11.5, and the calcination temperature of the calcination treatment is 200-400°C.

[0046] According to the embodiments of the present disclosure, a copper-manganese bimetallic oxide catalyst having a monoclinic copper oxide phase crystal structure is prepared by controlling the ratio of copper salt to manganese salt, the pH value of the alkaline solution, and the calcination temperature. The preparation method disclosed herein is simple, easy to implement, and low in cost, making it suitable for mass production.

[0047] According to embodiments of the present disclosure, the molar ratio of the copper salt to the manganese salt is 2 to 5:1, for example, 2:1, 3:1, 4:1, 5:1, etc. When the molar ratio of the copper salt to the manganese salt is controlled within the above range, the catalyst tends to form a monoclinic copper oxide (CuO) phase crystal structure. Conversely, when the amount of manganese salt exceeds the copper salt, the formed catalyst tends to exhibit a tetragonal manganese tetraoxide (Mn3O4) phase crystal structure. When the molar ratio of the copper salt to the manganese salt is close to 1:1, both monoclinic copper oxide and tetragonal manganese tetraoxide phase crystal structures coexist in the catalyst.

[0048] According to an embodiment of the present disclosure, the pH value of the alkaline solution is 9.5~11.5, for example, it can be 9.5, 10, 10.5, 11, 11.5, etc. When the pH value is within the range of 9.5~11.5, the hydroxide ions first react with the copper ions to form a precipitate, and then react with the manganese ions, which can provide a basis for the subsequent generation of a monoclinic copper oxide phase crystal structure, and for the embedding of manganese ions into the monoclinic copper oxide lattice. When the pH value is too high, a large amount of hydroxide ions will react rapidly with the copper ions and manganese ions, resulting in rapid precipitation, making it easy for copper and manganese to interact with each other, thereby tending to generate a spinel phase crystal structure. When the pH value is less than 9.5, it is difficult to meet the requirement of adjusting the pH value of the mixed solution to 9~11, and the copper ions and manganese ions cannot be completely precipitated, thereby affecting the formation of subsequent crystal structures.

[0049] According to the embodiments of the present disclosure, the calcination temperature is 200-400°C, for example, 200°C, 250°C, 300°C, 350°C, 400°C, etc. The appropriate calcination temperature can promote the formation of monoclinic copper oxide phase and improve the catalytic activity and stability of the catalyst. When the calcination temperature is too high, the catalyst tends to form cubic copper manganese spinel (Cu 1.5 Mn 1.5 O4) phase structure, and when the temperature is too low, the catalyst crystal structure may be unstable, which is not conducive to the catalytic reaction.

[0050] According to an embodiment of the present disclosure, the heating temperature for obtaining the precipitate is 60-90°C, for example, 60°C, 70°C, 80°C, 85°C, 90°C, etc., and the heating time is 2-6 hours, for example, 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, etc. The calcination atmosphere for the precipitate is air. The oxidizing environment during the calcination process helps to change the oxidation state of the metal in the catalyst, thereby adjusting the electronic structure and active sites of the catalyst. The calcination time is 3-6 hours, for example, 3 hours, 4 hours, 5 hours, 6 hours, etc.

[0051] According to the embodiments of the present disclosure, the copper salt and manganese salt are soluble salts selected from any one of nitrates, sulfates, and citrates. The soluble salts are readily soluble in water to form a uniform ionic solution, which facilitates uniform ion distribution during the preparation of the manganese-copper bimetallic oxide catalyst, thereby obtaining a catalyst with uniform performance. The alkaline solution is selected from any one of an aqueous ammonia solution, a carbonate solution, and a hydroxide solution. The pH value of the mixed solution ranges from 9 to 11, for example, the pH value can be 9, 9.5, 10, 10.5, 11, etc.

[0052] According to an embodiment of yet another aspect of the present disclosure, there is provided a use of the copper-manganese bimetallic oxide catalyst in the degradation of volatile organic compounds.

[0053] According to the embodiments of the present disclosure, in a copper-manganese bimetallic oxide catalyst having a monoclinic copper oxide phase crystal structure, manganese metal is embedded in the monoclinic copper oxide phase lattice in ionic form, forming Cu-O-Mn sites. This not only improves the electronic structure of the catalyst, but also significantly enhances the oxidizing ability of active oxygen species and the migration ability of oxygen species within the catalyst, forming a stable MvK cycle and achieving a higher redox capacity. This allows the copper-manganese bimetallic oxide catalyst to not only achieve more efficient and deeper degradation of volatile organic pollutants, but also reduces the generation of gaseous byproducts and improves the performance of completely oxidizing pollutants to carbon dioxide.

[0054] According to an embodiment of the present disclosure, the degradation method includes:

[0055] A copper-manganese bimetallic oxide catalyst and volatile organic compounds were placed in a reactor, and a mixed gas was introduced. The oxygen content in the mixed gas was controlled to be 5-20%, and the relative humidity was controlled to be 0-30%. The appropriate humidity simulates the reaction environment under actual working conditions, thus increasing the guarantee for the practical application of the catalyst. At the same time, the space velocity of the copper-manganese bimetallic oxide catalyst was controlled to be 30,000-100,000 mL·g -1 ·h -1The appropriate space velocity range ensures sufficient contact time between air and catalyst, allowing oxygen and volatile organic compounds to be effectively transferred to the catalyst surface, while avoiding the reactants being carried away without sufficient reaction due to excessive flow rate. Under heating conditions of 100~500℃, the copper-manganese bimetallic oxide catalyst is used to degrade volatile organic compound pollutants. The catalyst can be activated in a lower temperature range, allowing the catalyst to effectively promote the degradation reaction of volatile organic compounds. Among them, the volatile organic compound concentration can be, for example, 100~1000 ppm, and the amount of copper-manganese bimetallic oxide catalyst used is 50~200 mg. Adding a small amount of catalyst can achieve efficient degradation of pollutants. At the same time, the mild reaction conditions also significantly reduce energy consumption, making the copper-manganese bimetallic oxide catalyst show good application potential in environmental governance.

[0056] For example, the oxygen content in the mixed gas is 5-20%, for example, 5%, 8%, 10%, 15%, 20%, etc. An appropriate amount of oxygen can ensure the progress of the catalytic reaction, and oxygen interacts with the active sites on the catalyst surface to generate active oxygen species to promote the redox reaction; the relative humidity is 0-30%, for example, 0%, 5%, 8%, 10%, 15%, 20%, 30%, etc. When treating volatile organic pollutants under different relative humidity conditions, the copper-manganese bimetallic oxide catalyst can exhibit good water resistance; the catalyst space velocity is 30,000-100,000 mL·g -1 ·h -1 , for example, it can be 30000 mL·g -1 ·h -1 , 50000 mL·g -1 ·h -1 、70000 mL·g -1 ·h -1 , 90000 mL·g -1 ·h -1 、100000 mL·g -1 ·h -1 etc.; the heating temperature during the degradation process is 100~500℃, for example, it can be 100℃, 150℃, 200℃, 250℃, 300℃, 400℃, 500℃, etc., and different degradation reaction temperatures can be selected according to different volatile organic compounds. The copper-manganese bimetallic oxide catalyst has better low-temperature activity.

[0057] According to embodiments of the present disclosure, volatile organic compounds include any one of C1-C8 alkanes, alkenes, and aromatic hydrocarbons. Examples of alkane volatile organic compounds include cyclohexane, n-hexane, and propane; examples of olefin volatile organic compounds include 1,3-butadiene, ethylene, propylene, and styrene; and examples of aromatic hydrocarbon volatile organic compounds include benzene, toluene, and xylene.

[0058] In order to make the purpose, technical solutions and advantages of the present disclosure more clearly understood, the present disclosure is further described in detail below in conjunction with specific examples and drawings. Where specific techniques or conditions are not specified in the examples, they are all conventional methods and can be carried out according to the techniques or conditions described in the literature in the field or according to the product instructions. It should be noted that the methods provided in the present disclosure are all conventional methods unless otherwise specified, and the reactants and reagents can be obtained from public commercial channels unless otherwise specified.

[0059] Example 1:

[0060] This embodiment 1 provides a method for preparing a copper-manganese bimetallic oxide catalyst, and the specific steps are as follows:

[0061] Weigh 2.1744 g of copper nitrate trihydrate and 1.0737 g of 50 wt.% manganese nitrate solution and add them to a 250 mL round-bottom flask along with 150 mL of deionized water. Add a magnetic stirrer and place the mixture in an oil bath at 90°C for 5 minutes to ensure complete dissolution and a homogeneous mixture.

[0062] Gradually add ammonia solution with a pH of 10.5 to adjust the pH of the mixed solution to 10. Continue heating and stirring the reaction for 3 hours to form a precipitate. After the flask cools to room temperature, wash the precipitate several times with deionized water and then dry it at 60°C for 12 hours to obtain a dried precipitate.

[0063] The dried precipitate was calcined in a tube furnace at 300°C for 6 h under air atmosphere to obtain a copper-manganese bimetallic oxide catalyst (abbreviated as Cu3Mn1) with a copper-manganese molar ratio of 3:1.

[0064] The copper-manganese bimetallic oxide catalyst prepared in Example 1 was subjected to structural characterization and activity testing. Figure 1 1 is a scanning electron microscope image of the copper-manganese bimetallic oxide catalyst in Example 1, wherein a is a scanning electron microscope image of the copper-manganese bimetallic oxide catalyst in Example 1 at a scale of 500 nm, and b is a scanning electron microscope image of the copper-manganese bimetallic oxide catalyst in Example 1 at a scale of 200 nm; Figure 1a is a transmission electron microscope elemental mapping image of the copper-manganese bimetallic oxide catalyst in Example 1; Figure 1b This is the X-ray diffraction pattern of the copper-manganese bimetallic oxide catalyst in Example 1.

[0065] like Figure 1 As shown, the copper-manganese bimetallic oxide catalyst prepared in Example 1 exhibits a nanosheet structure. Figure 1a As shown, copper and manganese elements are evenly distributed in the catalyst prepared in Example 1. Figure 1b As shown, the crystal structure of the catalyst prepared in Example 1 is a monoclinic copper oxide (CuO) phase.

[0066] The effect of the copper-manganese bimetallic oxide catalyst prepared in Example 1 in degrading alkane volatile organic compounds was tested. The copper-manganese bimetallic oxide catalyst prepared in Example 1 was used to degrade cyclohexane, comprising the following steps:

[0067] 100 mg of the copper-manganese bimetallic oxide catalyst prepared in Example 1 and 500 ppm of cyclohexane were placed in a glass tube and introduced at a total flow rate of 80 mL min -1 The mixed gas has an oxygen content of 5%, a relative humidity of 5%, and a catalyst space velocity of 48000 mL·g -1 ·h -1 , N2 is used as the balance gas. The treatment experiment of cyclohexane was carried out at a reaction temperature of 100~300℃. The specific test results are as follows Figure 2a shown.

[0068] Figure 2a This is a graph showing the degradation efficiency of cyclohexane by the copper-manganese bimetallic oxide catalyst in Example 1 at different temperatures.

[0069] like Figure 2a As shown, the degradation rate of cyclohexane is 10% at about 128°C, and the degradation rate of cyclohexane reaches 90% at about 219°C. It can be observed that the copper-manganese bimetallic oxide catalyst in Example 1 exhibits high degradation activity for cyclohexane.

[0070] Furthermore, the effect of the copper-manganese bimetallic oxide catalyst prepared in Example 1 in degrading aromatic volatile organic compounds was tested. The copper-manganese bimetallic oxide catalyst prepared in Example 1 was used to degrade benzene. The specific degradation process is as follows:

[0071] 100 mg of the copper-manganese bimetallic oxide catalyst prepared in Example 1 and 500 ppm of benzene were placed in a glass tube and introduced at a total flow rate of 80 mL min -1 The mixed gas has an oxygen content of 5%, a relative humidity of 5%, and a catalyst space velocity of 48000 mL·g -1 ·h -1Benzene treatment experiments were conducted at reaction temperatures of 100-300°C. The specific test results are as follows: Figure 2b shown.

[0072] Figure 2b This is a graph showing the degradation efficiency of the copper-manganese bimetallic oxide catalyst for benzene at different temperatures in Example 1.

[0073] like Figure 2b As shown, the degradation rate of cyclohexane is 10% at about 159°C, and the degradation rate of cyclohexane reaches 90% at about 237°C. It can be observed that the copper-manganese bimetallic oxide catalyst in Example 1 exhibits high degradation activity for benzene.

[0074] The effect of the copper-manganese bimetallic oxide catalyst prepared in Example 1 in degrading olefin volatile organic compounds was tested. The copper-manganese bimetallic oxide catalyst prepared in Example 1 was used to degrade 1,3-butadiene. The specific degradation process is as follows:

[0075] 100 mg of the copper-manganese bimetallic oxide catalyst prepared in Example 1 and 500 ppm of 1,3-butadiene were weighed and placed in a glass tube. The total flow rate was 80 mL min -1 The mixed gas has an oxygen content of 5%, a relative humidity of 5%, and a catalyst space velocity of 48000 mL·g -1 ·h -1 , N2 is used as the balance gas. The treatment experiment of 1,3-butadiene was carried out at a reaction temperature of 100~260℃. The specific test results are as follows Figure 2c shown.

[0076] Figure 2c This is a graph showing the degradation efficiency of the copper-manganese bimetallic oxide catalyst for 1,3-butadiene at different temperatures in Example 1.

[0077] like Figure 2c As shown, the degradation rate of 1,3-butadiene is 10% at about 129°C, and the degradation rate of 1,3-butadiene is 90% at about 178°C. It can be observed that the copper-manganese bimetallic oxide catalyst in Example 1 exhibits high degradation activity for 1,3-butadiene.

[0078] The copper-manganese bimetallic oxide catalyst prepared in Example 1 was subjected to a water resistance test, and the specific degradation process was as follows:

[0079] 100 mg of the copper-manganese bimetallic oxide catalyst prepared in Example 1 and 500 ppm of cyclohexane were placed in a glass tube and introduced at a total flow rate of 80 mL min -1 The mixed gas has an oxygen content of 5% and a catalyst space velocity of 48000 mL·g-1 ·h -1 The cyclohexane treatment experiments were conducted at reaction temperatures ranging from 100°C to 300°C, with N2 as the balance gas. The relative humidity was adjusted to 0%, 5%, and 10%, respectively.

[0080] Figure 2d This is a graph showing the degradation efficiency of cyclohexane by the copper-manganese bimetallic oxide catalyst in Example 1 under dry conditions and different relative humidity conditions.

[0081] like Figure 2d As shown, it can be observed that under dry conditions, 5% and 10% relative humidity, the degradation rate of cyclohexane by the catalyst is almost the same, indicating that the copper-manganese bimetallic oxide catalyst in Example 1 has good water resistance and has excellent catalytic effect under different relative humidity environments.

[0082] Furthermore, the copper-manganese bimetallic oxide catalyst prepared in Example 1 was subjected to a stability test. The specific test process is as follows:

[0083] 100 mg of the copper-manganese bimetallic oxide catalyst prepared in Example 1 and 500 ppm of cyclohexane were placed in a glass tube and introduced at a total flow rate of 80 mL min -1 The mixed gas has an oxygen content of 5%, a relative humidity of 5%, and a catalyst space velocity of 48000 mL·g -1 ·h -1 The cyclohexane treatment experiment was carried out at a reaction temperature of 260°C for 48 hours.

[0084] Figure 2e This is a graph showing the degradation efficiency of cyclohexane by the copper-manganese bimetallic oxide catalyst in Example 1 at 260°C within 48 hours.

[0085] like Figure 2e As shown, it can be observed that the degradation rate of cyclohexane by the copper-manganese bimetallic oxide catalyst in Example 1 is maintained at about 99% within 48 h, showing good stability.

[0086] Example 2

[0087] This Example 2 provides a method for preparing a copper-manganese bimetallic oxide catalyst. This method differs from Example 1 in that 1.9328 g of copper nitrate trihydrate and 1.4316 g of a 50 wt.% manganese nitrate solution are weighed in Example 2. All other steps are the same as in Example 1, yielding a copper-manganese bimetallic oxide catalyst (abbreviated as Cu2Mn1) with a copper-manganese molar ratio of 2:1.

[0088] The copper-manganese bimetallic oxide catalyst prepared in Example 2 was subjected to structural characterization and activity testing. Figure 3aThis is the X-ray diffraction pattern of the copper-manganese bimetallic oxide catalyst in Example 2.

[0089] like Figure 3a As shown, the crystal structure of the catalyst prepared in Example 2 is a monoclinic copper oxide phase.

[0090] The effect of the copper-manganese bimetallic oxide catalyst prepared in Example 2 in degrading alkane volatile organic compounds was tested. Cyclohexane was degraded using the copper-manganese bimetallic oxide catalyst prepared in Example 2. The specific test process is as follows:

[0091] 100 mg of the copper-manganese bimetallic oxide catalyst prepared in Example 2 and 500 ppm of cyclohexane were placed in a glass tube and introduced at a total flow rate of 80 mL min -1 The mixed gas has an oxygen content of 5%, a relative humidity of 5%, and a catalyst space velocity of 48000 mL·g -1 ·h -1 The cyclohexane treatment experiment was carried out at a reaction temperature of 100-300℃.

[0092] Figure 3b This is a graph showing the degradation efficiency of cyclohexane by the copper-manganese bimetallic oxide catalyst in Example 2 at different temperatures.

[0093] like Figure 3b As shown, the degradation rate of cyclohexane is 10% at about 132°C, and the degradation rate of cyclohexane is 90% at about 227°C. It can be observed that the copper-manganese bimetallic oxide catalyst in Example 2 exhibits higher degradation activity for cyclohexane.

[0094] Comparative Example 1

[0095] This comparative example 1 provides a method for preparing a copper-manganese bimetallic oxide catalyst, and the specific steps are as follows:

[0096] The difference from Example 1 is that in Comparative Example 1, 0.7248 g of copper nitrate trihydrate and 3.2211 g of a 50 wt.% manganese nitrate solution were weighed. All other steps were the same as in Example 1, yielding a copper-manganese bimetallic oxide catalyst (abbreviated as Cu1Mn3) with a copper-manganese molar ratio of 1:3.

[0097] The copper-manganese bimetallic oxide catalyst prepared in Comparative Example 1 was subjected to structural characterization and activity testing. Figure 4a This is the X-ray diffraction pattern of the copper-manganese bimetallic oxide catalyst in Comparative Example 1.

[0098] like Figure 4a As shown, the crystal structure of the catalyst prepared in Comparative Example 1 is a tetragonal manganese tetraoxide (Mn3O4) phase.

[0099] The effect of the copper-manganese bimetallic oxide catalyst prepared in Comparative Example 1 in degrading alkane volatile organic compounds was tested. Cyclohexane was degraded using the copper-manganese bimetallic oxide catalyst prepared in Comparative Example 1. The specific test process is as follows:

[0100] 100 mg of the copper-manganese bimetallic oxide catalyst prepared in Comparative Example 1 and 500 ppm of cyclohexane were placed in a glass tube and introduced at a total flow rate of 80 mL min -1 The mixed gas has an oxygen content of 5%, a relative humidity of 5%, and a catalyst space velocity of 48000 mL·g -1 ·h -1 The cyclohexane treatment experiment was carried out at a reaction temperature of 100-300℃.

[0101] Figure 4b This is a graph showing the degradation efficiency of cyclohexane by the copper-manganese bimetallic oxide catalyst in Comparative Example 1 at different temperatures.

[0102] like Figure 4b As shown, the degradation rate of cyclohexane is 10% at about 168°C, and the degradation rate of cyclohexane is 90% at about 273°C. It can be observed that the copper-manganese bimetallic oxide catalyst in Comparative Example 1 exhibits poor degradation activity for cyclohexane.

[0103] Comparative Example 2

[0104] This comparative example 2 provides a method for preparing a copper-manganese bimetallic oxide catalyst, and the specific steps are as follows:

[0105] Comparative Example 2 differs from Example 1 in that 1.4496 g of copper nitrate trihydrate and 2.1474 g of a 50 wt.% manganese nitrate solution were weighed. All other steps were the same as in Example 1, yielding a copper-manganese bimetallic oxide catalyst (abbreviated as Cu1Mn1) having a copper-manganese molar ratio of 1:1.

[0106] The copper-manganese bimetallic oxide catalyst prepared in Comparative Example 2 was subjected to structural characterization and activity testing. Figure 5a This is the X-ray diffraction pattern of the copper-manganese bimetallic oxide catalyst in Comparative Example 2.

[0107] like Figure 5a As shown, the crystal structure of the catalyst prepared in Comparative Example 2 includes cubic copper manganese spinel (Cu 1.5 Mn 1.5 O4) phase and monoclinic copper oxide phase, the main phase is Cu 1.5 Mn 1.5 O4 phase.

[0108] The effect of the copper-manganese bimetallic oxide catalyst prepared in Comparative Example 2 in degrading alkane volatile organic compounds was tested. Cyclohexane was degraded using the copper-manganese bimetallic oxide catalyst prepared in Comparative Example 2. The specific test process is as follows:

[0109] 100 mg of the copper-manganese bimetallic oxide catalyst prepared in Comparative Example 2 and 500 ppm of cyclohexane were placed in a glass tube and introduced at a total flow rate of 80 mL min -1 The mixed gas has an oxygen content of 5%, a relative humidity of 5%, and a catalyst space velocity of 48000 mL·g -1 ·h -1 The cyclohexane treatment experiment was carried out at a reaction temperature of 100-300℃.

[0110] Figure 5b This is a graph showing the degradation efficiency of cyclohexane by the copper-manganese bimetallic oxide catalyst in Comparative Example 2 at different temperatures.

[0111] like Figure 5b As shown, the degradation rate of cyclohexane is 10% at about 144°C, and the degradation rate of cyclohexane is 90% at about 256°C. It can be observed that the copper-manganese bimetallic oxide catalyst in Comparative Example 2 exhibits poor degradation activity for cyclohexane.

[0112] Comparative Example 3

[0113] This comparative example 3 provides a method for preparing a copper single metal oxide catalyst, and the specific steps are as follows:

[0114] The difference from Example 1 is that only 2.8992 g of copper nitrate trihydrate was weighed for catalyst preparation in Comparative Example 3. The other steps were the same as in Example 1 to prepare a copper monometallic oxide catalyst (abbreviated as CuO).

[0115] The effect of the copper-manganese bimetallic oxide catalyst prepared in Comparative Example 3 in degrading alkane volatile organic compounds was tested, and the copper monometallic oxide catalyst prepared in Comparative Example 3 was used to degrade cyclohexane. The specific test process is as follows:

[0116] 100 mg of the copper monometallic oxide catalyst prepared in Comparative Example 3 and 500 ppm of cyclohexane were weighed and placed in a glass tube. The total flow rate was 80 mL min. -1 The mixed gas has an oxygen content of 5%, a relative humidity of 5%, and a catalyst space velocity of 48000 mL·g -1 ·h -1 The cyclohexane treatment experiment was carried out at a reaction temperature of 100-300℃.

[0117] Figure 6 This is a graph showing the degradation efficiency of cyclohexane by the copper single metal oxide catalyst in Comparative Example 3 at different temperatures.

[0118] like Figure 6 As shown, the degradation rate of cyclohexane is 10% at about 214°C, and the degradation rate of cyclohexane is 90% at about 299°C. It can be observed that the copper single metal oxide catalyst in Comparative Example 3 has poor activity in degrading cyclohexane.

[0119] Comparative Example 4

[0120] This comparative example 4 provides a method for preparing a manganese single metal oxide catalyst, and the specific steps are as follows:

[0121] The difference from Example 1 is that in Comparative Example 4, only 4.24948 g of 50 wt.% manganese nitrate solution was weighed for catalyst preparation. All other steps were the same as in Example 1 to prepare a manganese monometallic oxide catalyst (abbreviated as Mn3O4).

[0122] The effect of the copper-manganese bimetallic oxide catalyst prepared in Comparative Example 4 in degrading alkane volatile organic compounds was tested, and the manganese monometallic oxide catalyst prepared in Comparative Example 4 was used to degrade cyclohexane. The specific test process is as follows:

[0123] 100 mg of the manganese monometallic oxide catalyst prepared in Comparative Example 4 and 500 ppm of cyclohexane were weighed and placed in a glass tube. The total flow rate was 80 mL min -1 The mixed gas has an oxygen content of 5%, a relative humidity of 5%, and a catalyst space velocity of 48000 mL·g -1 ·h -1 The cyclohexane treatment experiment was carried out at a reaction temperature of 100-300℃.

[0124] Figure 7 This is a graph showing the degradation efficiency of cyclohexane by the manganese single metal oxide catalyst in Comparative Example 4 at different temperatures.

[0125] like Figure 7 As shown, the degradation rate of cyclohexane is 10% at about 199°C, and the degradation rate of cyclohexane is 90% at about 289°C. It can be observed that the manganese single metal oxide catalyst in Comparative Example 4 has poor activity in degrading cyclohexane.

[0126] Comparative Example 5

[0127] Comparative Example 5 provides a method for preparing a copper-manganese bimetallic oxide catalyst. This method differs from Example 1 in that, in Comparative Example 5, an aqueous ammonia solution having a pH of 12 is gradually added to adjust the pH of the mixed solution to 10. The remaining steps are the same as in Example 1, yielding a copper-manganese bimetallic oxide catalyst having a copper-manganese molar ratio of 3:1 (referred to as Cu3Mn1-spinel).

[0128] The copper-manganese bimetallic oxide catalyst prepared in Comparative Example 5 was subjected to structural characterization and activity testing. Figure 8a This is the X-ray diffraction pattern of the copper-manganese bimetallic oxide catalyst in Comparative Example 5.

[0129] like Figure 8a As shown, the main phase of the crystal structure of the catalyst prepared in Comparative Example 5 is a monoclinic copper oxide phase, but a cubic copper-manganese spinel miscellaneous phase also exists.

[0130] The effect of the copper-manganese bimetallic oxide catalyst prepared in Comparative Example 5 in degrading alkane volatile organic compounds was tested. Cyclohexane was degraded using the copper-manganese bimetallic oxide catalyst prepared in Comparative Example 5. The specific test process is as follows:

[0131] 100 mg of the copper-manganese bimetallic oxide catalyst prepared in Comparative Example 5 and 500 ppm of cyclohexane were placed in a glass tube and introduced at a total flow rate of 80 mL min -1 The mixed gas has an oxygen content of 5%, a relative humidity of 5%, and a catalyst space velocity of 48000 mL·g -1 ·h -1 The cyclohexane treatment experiment was carried out at a reaction temperature of 100-300℃.

[0132] Figure 8b This is a graph showing the degradation efficiency of cyclohexane at different temperatures using the copper-manganese bimetallic oxide catalyst in Comparative Example 5.

[0133] like Figure 8b As shown, the degradation rate of cyclohexane is 10% at about 150°C, and the degradation rate of cyclohexane is 90% at about 258°C. It can be observed that the degradation activity of the copper-manganese bimetallic oxide catalyst in Comparative Example 5 for cyclohexane is lower than that of the copper-manganese bimetallic oxide catalyst in Example 1, and a higher temperature is required to achieve efficient degradation of cyclohexane.

[0134] Comparative Example 6

[0135] Comparative Example 6 provides a method for preparing a copper-manganese bimetallic oxide catalyst. This method differs from Example 1 in that the dried precipitate is calcined in a tube furnace at 500°C for 6 hours. All other steps are the same as in Example 1, yielding a copper-manganese bimetallic oxide catalyst having a copper-manganese molar ratio of 3:1 (abbreviated as Cu3Mn1-500°C).

[0136] The copper-manganese bimetallic oxide catalyst prepared in Comparative Example 6 was structurally characterized. Figure 9 This is the X-ray diffraction pattern of the copper-manganese bimetallic oxide catalyst in Comparative Example 6.

[0137] like Figure 9 As shown, the main phase of the crystal structure of the catalyst prepared in Comparative Example 6 is a monoclinic copper oxide phase, but a cubic copper-manganese spinel miscellaneous phase also exists.

[0138] By comparing the crystal structures of the copper-manganese bimetallic oxide catalysts of Example 1, Example 2 and Comparative Examples 1, 2, 5 and 6, it can be found that only by reasonably selecting the molar ratio of copper and manganese, the pH value of the alkaline solution and the calcination temperature can the crystal structure of the catalyst be controlled to be a monoclinic copper oxide (CuO) phase.

[0139] By comparing the volatile organic compound degradation activity of the catalysts in Example 1, Example 2 and Comparative Examples 1, 2, 3, 4 and 5, it can be found that the catalytic activity of the copper-manganese bimetallic oxide catalyst for cyclohexane is higher than that of the single metal oxide catalyst, indicating that the interaction between copper and manganese metals can improve the activity of the catalyst.

[0140] By comparing the volatile organic compound degradation activity of the catalysts in Example 1, Example 2 and Comparative Examples 1, Comparative Example 2, and Comparative Example 5, it can be found that among the copper-manganese bimetallic oxide catalysts, the catalyst activity with a crystal structure of monoclinic copper oxide phase is higher than the catalyst activity with a crystal structure of spinel phase.

[0141] The byproducts of the catalysts in Example 1 and Comparative Examples 1, 3, and 4 during the degradation of cyclohexane were quantitatively analyzed, the steps comprising:

[0142] The tail gases generated during the degradation of cyclohexane by the four catalysts were collected separately, and the by-products in the tail gases were qualitatively and quantitatively analyzed by gas chromatography-flame ionization detector / mass spectrometry detector (GC-FID / MSD).

[0143] Figure 10 1 is a diagram showing the distribution of by-products during the degradation of cyclohexane by the catalyst in Example 1 and Comparative Examples 1, 3, and 4.

[0144] like Figure 10As shown, when cyclohexane was degraded using the catalysts in Example 1 and Comparative Examples 1, 3, and 4, a total of 23 by-products were detected in the tail gas. The catalyst in Example 1 significantly reduced the total amount of by-products generated compared to the catalysts in Comparative Examples 1, 3, and 4, indicating that the copper-manganese bimetallic oxide catalyst having a crystal structure of monoclinic copper oxide phase in Example 1 has excellent deep oxidation performance, and can more thoroughly oxidize cyclohexane into carbon dioxide and water, reducing the generation of by-products. It further confirms that the copper-manganese bimetallic oxide catalyst of monoclinic copper oxide phase prepared in Example 1 has a strong catalytic oxidation ability and can efficiently degrade volatile organic compounds.

[0145] The catalysts prepared in Example 1, Example 2, Comparative Example 1, Comparative Example 2, Comparative Example 3, and Comparative Example 4 were subjected to an oxygen temperature-programmed desorption (O2-TPD) test to explore the oxygen species migration ability in the catalysts. The specific test process is as follows:

[0146] 50 mg of the catalyst prepared in Example 1, Example 2, Comparative Example 1, Comparative Example 2, Comparative Example 3, and Comparative Example 4 were weighed and introduced into the catalyst at a total flow rate of 30 mL·min at 300°C. -1 The sample was pretreated under 5% O2 / He gas flow for 2 h, and then cooled to 50 °C. The sample was purged under helium (He) atmosphere for 1 h to remove the oxygen physically adsorbed on the surface. After the baseline was stable, 30 mL min -1 Helium, at 10℃·min -1 The temperature was raised to 800 °C at a rate of 100 ℃, and the amount of desorbed oxygen was monitored in real time using a thermal conductivity detector (TCD).

[0147] Figure 11 Attached are the oxygen temperature-programmed desorption diagrams of the catalysts in Example 1, Example 2, Comparative Example 1, Comparative Example 2, Comparative Example 3 and Comparative Example 4.

[0148] like Figure 11 As shown, the lattice oxygen desorption peak temperature of the catalyst surface prepared in Example 1 and Example 2 is lower than that in Comparative Example 1, Comparative Example 2, Comparative Example 3 and Comparative Example 4, indicating that the copper-manganese bimetallic oxide catalyst with a monoclinic copper oxide phase crystal structure in Example 1 and Example 2 has a strong oxygen species mobility ability, which is beneficial to the continuous replenishment of oxygen during the catalytic reaction.

[0149] Furthermore, compared with the single metal oxide catalysts in Comparative Examples 3 and 4, the activity of the copper-manganese bimetallic oxide catalysts in Comparative Examples 1 and 2 was improved, but the effect was limited. The copper-manganese bimetallic oxide catalysts in Comparative Examples 1 and 2 had electron transfer between copper and manganese:

[0150]

[0151] The electronic interaction between copper and manganese improves the redox ability of the catalyst to a certain extent. In the copper-manganese bimetallic oxide catalyst with a crystal structure of monoclinic copper oxide phase in Example 1 and Example 2, manganese ions can be embedded in the lattice of the monoclinic copper oxide phase, forming a special Cu-O-Mn site, thereby changing the electronic structure of the catalyst and enhancing the redox ability of the material. Compared with the performance improvement brought about by electron transfer between copper and manganese, the enhancement effect of the Cu-O-Mn site is more prominent. In addition, the Cu-O-Mn site also promotes the migration ability of oxygen species, thereby enhancing the oxidation ability of active oxygen species, improving the activation efficiency of oxygen, and enabling the catalyst to exhibit more abundant acidic sites, promoting the formation of a faster and more stable Mars-van-Krevelen (MvK) cycle, thereby achieving efficient degradation of volatile organic compounds.

[0152] Therefore, the copper-manganese bimetallic oxide catalyst with a monoclinic copper oxide phase crystal structure has excellent catalytic activity, water resistance and stability, and can achieve efficient degradation of volatile organic compounds including alkanes, alkenes and aromatic hydrocarbons, which is beneficial to the removal of volatile organic compounds in actual industrial exhaust gas.

[0153] The specific embodiments described above further illustrate the purpose, technical solutions and beneficial effects of the present disclosure. It should be understood that the above are only specific embodiments of the present disclosure and are not intended to limit the present disclosure. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present disclosure should be included in the scope of protection of the present disclosure.

Claims

1. A copper-manganese bimetallic oxide catalyst, characterized in that: The crystal structure of the copper-manganese bimetallic oxide catalyst is a monoclinic copper oxide phase. The manganese metal is embedded in the monoclinic copper oxide phase lattice in the form of ions.

2. The catalyst according to claim 1, characterized in that The copper-manganese bimetallic oxide catalyst has a morphology including a nanosheet structure.

3. A method for preparing the copper-manganese bimetallic oxide catalyst according to any one of claims 1 to 2, comprising: Mixing copper salt and manganese salt in water in proportion to form a mixed solution, adding an alkaline solution to adjust the pH value of the mixed solution, and heating to obtain a precipitate; calcining the precipitate to obtain the copper-manganese bimetallic oxide catalyst; The molar ratio of the copper salt to the manganese salt is 2-5:1, the pH value of the alkaline solution is 9.5-11.5, and the calcination temperature of the calcination treatment is 200-400°C.

4. The preparation method according to claim 3, characterized in that: The copper salt and manganese salt are soluble salts, selected from any one of nitrate, sulfate and citrate; The alkaline solution is selected from any one of an aqueous ammonia solution, a carbonate solution, and a hydroxide solution; The pH value of the mixed solution is in the range of 9 to 11.

5. The preparation method according to claim 3, characterized in that: The calcination atmosphere is air atmosphere, and the calcination time is 3~6 h; The heating temperature is 60-90° C., and the heating time is 2-6 h.

6. Use of the copper-manganese bimetallic oxide catalyst as claimed in any one of claims 1 to 2 in the degradation of volatile organic compounds.

7. The use according to claim 6, characterized in that: The degradation method comprises: The copper-manganese bimetallic oxide catalyst and the volatile organic matter are placed in a reactor, a mixed gas is introduced, and the volatile organic matter is degraded under heating conditions.

8. The use according to claim 6, characterized in that: The volatile organic compounds include any one of alkane, olefin and aromatic hydrocarbon volatile organic compounds.

9. The use according to claim 7, characterized in that: The oxygen content in the mixed gas is 5-20%; The space velocity of the copper-manganese bimetallic oxide catalyst is 30,000-100,000 mL·g -1 ·h -1 ; The heating temperature is 100-500°C.

10. The use according to claim 7, characterized in that: The relative humidity of the mixed gas is 0-30%.

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