Cu-doped lanthanum manganate perovskite catalyst as well as preparation method and application thereof

Abstract

The invention belongs to the field of catalyst material preparation, and discloses a Cu-doped lanthanum manganate perovskite catalyst as well as a preparation method and application thereof, and the chemical formula of the Cu-doped lanthanum manganate perovskite catalyst is LaMn < 1-x > CuxO < 3 >, wherein x ranges from 0.1 to 0.5. The preparation method of the Cu-doped lanthanum manganate perovskite catalyst comprises the following steps: weighing lanthanum nitrate, manganese acetate and copper nitrate according to the molar ratio of lanthanum to manganese to copper in the chemical formula LaMn1-xCuxO3; wherein x ranges from 0.1 to 0.5; dissolving lanthanum nitrate, manganese acetate, copper nitrate and citric acid in deionized water to obtain a mixed solution; and heating the mixed solution to obtain gel, drying the gel into solid powder, grinding the solid powder, and calcining to obtain the Cu-doped lanthanum manganate perovskite catalyst. The preparation process is simple and convenient, precious metal is not used, preparation conditions are mild, industrialization is facilitated, and the problems that a traditional catalyst is high in cost and poor in high temperature resistance, and active components are prone to sintering are solved.

Description

Technical Field

[0001] The invention belongs to the field of catalyst material preparation, and relates to a Cu-doped lanthanum manganate perovskite catalyst and a preparation method and application thereof. Background Art

[0002] Green ammonia blending is one of the three ways to reduce emissions from coal-fired power units. Ammonia, as a fuel without greenhouse gas emissions, has an energy density comparable to that of low-rank coal (22.5MJ / kg). Due to its many years of development and widespread application in agriculture and power plant denitrification, its mature production process and easy transportation provide a new way for the energy industry, especially the power industry, to achieve significant carbon reduction. In order to improve ammonia combustion performance and reduce nitrogen oxide emissions, catalytic combustion is a way with relatively low transformation costs.

[0003] At present, the research on ammonia combustion catalysts is still in its preliminary stage, and the relevant research results are relatively limited, and these studies mainly focus on application scenarios with low ammonia concentrations and low temperatures. In this field, although researchers have made many efforts, the existing technology still seems to be unable to cope with the challenges under high-temperature conditions. In particular, the current supported catalysts used for ammonia combustion often face the serious problem of easy sintering of active components under high-temperature environments. This sintering phenomenon will not only lead to a significant decrease in the activity of the catalyst, thereby affecting the combustion efficiency of ammonia, but also shorten the service life of the catalyst and increase operating costs. Summary of the invention

[0004] The purpose of the present invention is to overcome the shortcomings of the above-mentioned prior art and provide a Cu-doped lanthanum manganate perovskite catalyst and a preparation method and application thereof.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] In a first aspect of the present invention, a Cu-doped lanthanum manganate perovskite catalyst is provided, wherein the chemical formula of the Cu-doped lanthanum manganate perovskite catalyst is LaMn 1-x Cu x O 3 ; Wherein, x is 0.1~0.5.

[0007] In a second aspect of the present invention, a method for preparing a Cu-doped lanthanum manganate perovskite catalyst is provided, comprising: preparing a Cu-doped lanthanum manganate perovskite catalyst according to the chemical formula LaMn 1-x Cu x O 3The molar ratio of lanthanum, manganese and copper is as follows: lanthanum nitrate, manganese acetate and copper nitrate are weighed; wherein x is 0.1 to 0.5; lanthanum nitrate, manganese acetate, copper nitrate and citric acid are dissolved in deionized water to obtain a mixed solution; the mixed solution is heated to obtain a gel, and the gel is dried to a solid powder, and the solid powder is ground and calcined to obtain a Cu-doped lanthanum manganate perovskite catalyst.

[0008] Optionally, dissolving lanthanum nitrate, manganese acetate, copper nitrate and citric acid in deionized water to obtain a mixed solution includes: dissolving lanthanum nitrate, manganese acetate and copper nitrate in deionized water to obtain a first solution; dissolving citric acid in deionized water to obtain a second solution; and mixing the first solution and the second solution to obtain a mixed solution.

[0009] Optionally, the molar ratio of the total amount of the lanthanum nitrate, manganese acetate and copper nitrate to citric acid is 1:0.6-1.

[0010] Optionally, heating the mixed solution to obtain a gel comprises: heating the mixed solution in a water bath at 50 to 60° C. and stirring for 1 to 2 hours to obtain a gel.

[0011] Optionally, drying the gel into solid powder includes: drying the gel at 60-80° C. for 18-20 hours to obtain solid powder.

[0012] Optionally, when the solid powder is ground and then calcined, the calcination heating rate is 10-15°C / min, and the calcination is continued at 800-1000°C for 5-6 hours before cooling to room temperature.

[0013] Optionally, the x is 0.3.

[0014] In a third aspect of the present invention, a Cu-doped lanthanum manganate perovskite catalyst is provided, which is prepared by the above-mentioned method for preparing the Cu-doped lanthanum manganate perovskite catalyst.

[0015] In a fourth aspect, the present invention provides a use of the Cu-doped lanthanum manganate perovskite catalyst as described above in ammonia catalytic combustion.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] The Cu-doped lanthanum manganate perovskite catalyst of the present invention dopes Cu with good activity and selectivity into the B position of lanthanum manganate, and utilizes the ability of the valence state of metal manganese at the B position to change between +3 and +4, so that Cu and manganese form a synergistic effect, improve the oxygen storage and release ability of the catalyst, and thus improve the performance of the catalyst in the ammonia catalytic combustion reaction. 1-x Cu x O 3The catalyst uses cheap transition metals as active sites and fully retains the high-temperature resistant ordered structure of the perovskite catalyst, allowing Cu to be doped into the B site of the perovskite for uniform dispersion, avoiding the problems of high cost, poor high-temperature resistance and easy sintering of active components of traditional catalysts.

[0018] The present invention discloses a method for preparing a Cu-doped lanthanum manganate perovskite catalyst, which cleverly uses lanthanum nitrate, manganese acetate, copper nitrate, citric acid and deionized water as main raw materials. This preparation process is not only simple in steps and easy to operate, but also significantly reduces production costs, because it avoids the use of precious metals, which is particularly important in the context of current resource scarcity and increasingly important cost control. During the preparation process, by accurately regulating the ratio and reaction conditions of each raw material, it is possible to promote effective reactions between raw materials in a mild environment to form a Cu-doped lanthanum manganate perovskite catalyst with a specific structure and performance. The requirement of this mild condition not only reduces energy consumption, but also makes the entire production process safer and more environmentally friendly, laying a solid foundation for subsequent large-scale production. In addition, the preparation method of the present invention also shows a high degree of repeatability and stability, ensuring that the quality of each batch of catalysts is consistent, which is crucial for the performance of the catalyst in practical applications. At the same time, by adjusting the proportion of the doping element Cu, the catalytic activity, selectivity and stability of the catalyst can be further optimized to meet the needs of different catalytic reactions and broaden its scope of application.

[0019] The application of the Cu-doped lanthanum manganate perovskite catalyst in ammonia catalytic combustion greatly improves the performance of ammonia combustion and has a high NH 3 Conversion rate and N 2 Selective. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 The X-ray diffraction patterns of the catalysts prepared in Examples 1 to 3 of the present invention and the comparative example are shown.

[0021] Figure 2 This is a field emission scanning electron microscope (SEM) image of the Cu-doped lanthanum manganate perovskite catalyst prepared in Example 1 of the present invention.

[0022] Figure 3 This is a La element mapping diagram in the element energy spectrum mapping (EDS mapping) diagram of the Cu-doped lanthanum manganate perovskite catalyst prepared in Example 1 of the present invention.

[0023] Figure 4 This is a Mn element mapping diagram in the element spectrum mapping diagram of the Cu-doped lanthanum manganate perovskite catalyst prepared in Example 1 of the present invention.

[0024] Figure 5This is a Cu element mapping diagram in the element spectrum mapping diagram of the Cu-doped lanthanum manganate perovskite catalyst prepared in Example 1 of the present invention.

[0025] Figure 6 It is a comparison diagram of O1s in the X-ray electron spectroscopy diffraction analysis spectra of the catalysts prepared in Examples 1 to 3 of the present invention and the comparative example.

[0026] Figure 7 It is a comparison chart of Mn2p in the X-ray electron spectroscopy diffraction analysis spectra of the catalysts prepared in Examples 1 to 3 of the present invention and the comparative example.

[0027] Figure 8 This is a comparison diagram of Cu2p in the X-ray photoelectron spectroscopy diffraction analysis spectrum of the Cu-doped lanthanum manganate perovskite catalyst prepared in Examples 1 and 2 of the present invention.

[0028] Fig. 9 The NH3 combustion performance of ammonia under the catalysis of the catalysts prepared in Examples 1 to 3 of the present invention and the comparative examples and without the catalyst is shown in FIG. 3 Conversion rate comparison chart.

[0029] Fig.10 N is the ammonia combustion performance of the catalysts prepared in Examples 1 to 3 of the present invention and the comparative examples under catalysis and without catalyst. 2 Selective comparison chart. DETAILED DESCRIPTION

[0030] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0031] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0032] The present invention is further described in detail below in conjunction with the accompanying drawings:

[0033] In one embodiment of the present invention, a Cu-doped lanthanum manganate perovskite catalyst is provided, wherein the chemical formula of the Cu-doped lanthanum manganate perovskite catalyst is LaMn 1-x Cu x O 3 ; Wherein, x is 0.1~0.5.

[0034] The Cu-doped lanthanum manganate perovskite catalyst of the present invention dopes Cu with good activity and selectivity into the B position of lanthanum manganate, and utilizes the ability of the valence state of metal manganese at the B position to change between +3 and +4, so that Cu and manganese form a synergistic effect, improve the oxygen storage and release ability of the catalyst, and thus improve the performance of the catalyst in the ammonia catalytic combustion reaction. 1-x Cu x O 3 The catalyst uses cheap transition metals as active sites and fully retains the high-temperature resistant ordered structure of the perovskite catalyst, allowing Cu to be doped into the B site of the perovskite for uniform dispersion, avoiding the problems of high cost, poor high-temperature resistance and easy sintering of active components of traditional catalysts.

[0035] In another embodiment of the present invention, a method for preparing a Cu-doped lanthanum manganate perovskite catalyst is provided, comprising: 1-x Cu x O 3 The molar ratio of lanthanum, manganese and copper is as follows: lanthanum nitrate, manganese acetate and copper nitrate are weighed; wherein x is 0.1 to 0.5; lanthanum nitrate, manganese acetate, copper nitrate and citric acid are dissolved in deionized water to obtain a mixed solution; the mixed solution is heated to obtain a gel, and the gel is dried to a solid powder, and the solid powder is ground and calcined to obtain a Cu-doped lanthanum manganate perovskite catalyst.

[0036] In a possible embodiment, dissolving lanthanum nitrate, manganese acetate, copper nitrate and citric acid in deionized water to obtain a mixed solution includes: dissolving lanthanum nitrate, manganese acetate and copper nitrate in deionized water to obtain a first solution; dissolving citric acid in deionized water to obtain a second solution; and mixing the first solution and the second solution to obtain a mixed solution.

[0037] In a possible implementation manner, the molar ratio of the total amount of the lanthanum nitrate, manganese acetate and copper nitrate to citric acid is 1:0.6-1.

[0038] In a possible implementation, heating the mixed solution to obtain a gel comprises: heating the mixed solution in a water bath at 50 to 60° C. and stirring for 1 to 2 hours to obtain a gel.

[0039] In a possible implementation, drying the gel into solid powder includes: drying the gel at 60-80° C. for 18-20 hours to obtain solid powder.

[0040] In a possible implementation, when the solid powder is ground and then calcined, the calcination heating rate is 10-15° C. / min, and the calcination is continued at 800-1000° C. for 5-6 hours before cooling to room temperature.

[0041] The present invention discloses a method for preparing a Cu-doped lanthanum manganate perovskite catalyst, which cleverly uses lanthanum nitrate, manganese acetate, copper nitrate, citric acid and deionized water as main raw materials. This preparation process is not only simple in steps and easy to operate, but also significantly reduces production costs, because it avoids the use of precious metals, which is particularly important in the context of current resource scarcity and increasingly important cost control. During the preparation process, by accurately regulating the ratio and reaction conditions of each raw material, it is possible to promote effective reactions between raw materials in a mild environment to form a Cu-doped lanthanum manganate perovskite catalyst with a specific structure and performance. The requirement of this mild condition not only reduces energy consumption, but also makes the entire production process safer and more environmentally friendly, laying a solid foundation for subsequent large-scale production. In addition, the preparation method of the present invention also shows a high degree of repeatability and stability, ensuring that the quality of each batch of catalysts is consistent, which is crucial for the performance of the catalyst in practical applications. At the same time, by adjusting the proportion of the doping element Cu, the catalytic activity, selectivity and stability of the catalyst can be further optimized to meet the needs of different catalytic reactions and broaden its scope of application.

[0042] In summary, the preparation method of the Cu-doped lanthanum manganate perovskite catalyst of the present invention not only has readily available raw materials, simple process, and high cost-effectiveness, but also has excellent product performance and strong adjustability. It has extremely high industrialization potential and market application value, and has made important contributions to technological progress and green and sustainable development in the field of catalysis.

[0043] In another embodiment of the present invention, a Cu-doped lanthanum manganate perovskite catalyst is used in ammonia catalytic combustion to greatly improve the performance of ammonia combustion, with a high NH 3 Conversion rate and N 2 Selective.

[0044] The preparation method of the Cu-doped lanthanum manganate perovskite catalyst of the present invention is described below in conjunction with specific Examples 1 to 3 and Comparative Examples.

[0045] Example 1

[0046] A method for preparing a Cu-doped lanthanum manganate perovskite catalyst comprises the following steps:

[0047] 1. According to the chemical formula LaMn 1-x Cu x O 3 The molar ratio between lanthanum, manganese and copper is 0.5. Weigh lanthanum nitrate, manganese acetate and copper nitrate; where x is 0.5. Measure two 5mL portions of deionized water, add them to a beaker, and start stirring; add 5mmol of lanthanum nitrate, 2.5mmol of copper nitrate, and 2.5mmol of manganese acetate to one portion, and add 6mmol of citric acid to another portion, and stir for 10min respectively until completely dissolved.

[0048] 2. Mix the two solutions in step 1 and stir for 10 minutes until they are completely mixed to obtain a mixed solution.

[0049] 3. Transfer the mixed solution obtained in step 2 to a water bath, adjust the water bath temperature to 50°C, and stir continuously for 2 hours to obtain a gel.

[0050] 4. Transfer the gel obtained in step 3 to an oven, adjust the oven temperature to 80°C, dry for 18 hours, and fully grind the obtained solid powder for later use.

[0051] 5. Place the solid powder obtained in step 4 in a muffle furnace, adjust the heating rate of the muffle furnace to 10°C / min, stay at 800°C for 5 hours and then cool to room temperature to obtain a Cu-doped lanthanum manganate perovskite catalyst.

[0052] Example 2

[0053] A method for preparing a Cu-doped lanthanum manganate perovskite catalyst comprises the following steps:

[0054] 1. According to the chemical formula LaMn 1-x Cu x O 3 The molar ratio between lanthanum, manganese and copper is 0.3. Weigh lanthanum nitrate, manganese acetate and copper nitrate; where x is 0.3. Measure two 5mL portions of deionized water, add them to a beaker, and start stirring; add 5mmol of lanthanum nitrate, 1.5mmol of copper nitrate, and 3.5mmol of manganese acetate to one portion, and add 8mmol of citric acid to another portion, and stir for 10min respectively until completely dissolved.

[0055] 2. Mix the two solutions in step 1 and stir for 10 minutes until they are completely mixed to obtain a mixed solution.

[0056] 3. Transfer the mixed solution obtained in step 2 to a water bath, adjust the water bath temperature to 60°C, and stir continuously for 1.5 hours to obtain a gel.

[0057] 4. Transfer the gel obtained in step 3 to an oven, adjust the oven temperature to 70°C, dry for 18 hours, and fully grind the obtained solid powder for later use.

[0058] 5. The solid powder obtained in step 4 was placed in a muffle furnace, and the heating rate of the muffle furnace was adjusted to 13°C / min. After staying at 900°C for 5.5 hours, the mixture was cooled to room temperature to obtain a Cu-doped lanthanum manganate perovskite catalyst.

[0059] Example 3

[0060] A method for preparing a Cu-doped lanthanum manganate perovskite catalyst comprises the following steps:

[0061] 1. According to the chemical formula LaMn 1-x Cu x O 3 The molar ratio between lanthanum, manganese and copper is 0.1. Weigh lanthanum nitrate, manganese acetate and copper nitrate; where x is 0.1. Measure 5mL of deionized water in two portions, add them to a beaker, and start stirring; add 5mmol of lanthanum nitrate, 0.5mmol of copper nitrate, 4.5mmol of manganese acetate to one portion, and add 10mmol of citric acid to another portion, and stir for 10min respectively until completely dissolved.

[0062] 2. Mix the two solutions in step 1 and stir for 10 minutes until they are completely mixed to obtain a mixed solution.

[0063] 3. Transfer the mixed solution obtained in step 2 to a water bath, adjust the water bath temperature to 55°C, and stir continuously for 1.5 hours to obtain a gel.

[0064] 4. Transfer the gel obtained in step 3 to an oven, adjust the oven temperature to 60°C, dry for 18 hours, and fully grind the obtained solid powder for later use.

[0065] 5. Place the solid powder obtained in step 4 in a muffle furnace, adjust the heating rate of the muffle furnace to 15°C / min, stay at 1000°C for 6 hours, and then cool to room temperature to obtain a Cu-doped lanthanum manganate perovskite catalyst.

[0066] Comparative Example

[0067] The difference from Example 1 is that no copper is doped, that is, no copper nitrate is added to the raw material. The other processes are the same as those in Example 1, and finally a lanthanum manganate perovskite catalyst is obtained.

[0068] The Cu-doped lanthanum manganate perovskite catalysts obtained in Examples 1 to 3 and the lanthanum manganate perovskite catalysts obtained in the comparative example were used in a fixed bed ammonia catalytic combustion test, and the test conditions were 20% ammonia concentration and 77 to 1077°C.

[0069] See also Figure 1It can be seen that all samples are highly consistent with the diffraction peaks of PDF card #97-015-0260, which are monoclinic crystals with no impurity peaks, indicating that copper doping does not destroy the perovskite structure of lanthanum manganate, but is doped into the lattice rather than the surface, and has good crystallinity.

[0070] See also Figures 2 to 5 It can be seen that the Cu-doped lanthanum manganate perovskite catalyst of Example 1 presents a porous bridge structure, which is conducive to the adsorption of gas and the occurrence of catalytic reaction.

[0071] Elemental scanning analysis shows that La, Mn and O, as A / B components and active sites of perovskite, are evenly distributed in the entire space, and Cu also shows the same distribution pattern, which indicates that the location of Cu doping is in the perovskite lattice structure of lanthanum manganate, which is consistent with the conclusion of XRD, and further illustrates the advantage of loading copper active site catalysts in the form of doping, which can avoid the problem of agglomeration of active sites of traditional supported catalysts, thereby impairing performance.

[0072] See also Figure 6 , it can be seen that LaMn 1-x Cu x O 3 The oxygen species of the material are mainly concentrated in lattice oxygen and oxygen vacancies, and the proportion of oxygen vacancies is greater than 25%, which indicates that the Cu-doped lanthanum manganate perovskite catalyst has good oxidation performance.

[0073] Referring to Table 1, the distribution of Mn element species detected in the XPS spectra of the Cu-doped lanthanum manganate perovskite catalysts of Examples 1 to 3 is shown.

[0074] Table 1

[0075] Example <![CDATA[Mn 3+ Proportion]]> <![CDATA[Mn 4+ Proportion]]> <![CDATA[Mn 4+ / Mn 3+ ]]> Comparative Example 39.94％ 60.06％ 1.50 Example 3 31.09％ 68.91％ 2.22 Example 2 28.04％ 71.96％ 2.57 Example 1 19.14％ 80.86％ 4.22

[0076] See also Figure 7 , Figure 8 As can be seen from Table 1, LaMn 1-x Cu x O 3 Mn in the material is mainly Mn 3+ and Mn 4+ Cu was only detected in Example 1 and Example 2 with higher doping levels, mainly in the form of Cu 2+ With the gradual increase of Cu doping amount, the valence distribution of Mn and Cu elements in Cu-doped lanthanum manganate perovskite catalysts changed significantly, indicating that there is a synergistic effect between Cu and Mn. 4+ The proportion of species gradually increased, and the Mn 4+Since cations are more easily reduced to a lower oxidation state, they can accelerate the reaction and help improve the catalytic activity.

[0077] The catalysts of Examples 1-3 and the comparative example were subjected to a fixed bed catalytic combustion test, with a catalyst dosage of 0.2 g and a total gas volume of 300 mL min. -1 ; Ammonia concentration: 20%; O 2 Concentration: By equivalent ratio Calculation: The test was carried out under the reaction temperature of 77-1027℃.

[0078] See also Fig. 9 and 10 It can be seen that the introduction of the catalyst greatly improves the performance of ammonia combustion, reducing the ignition point of ammonia from about 800°C to 200-300°C, fully demonstrating the LaMn 1-x Cu x O material has good catalytic activity; in the entire test temperature range of 100-1000℃, the catalyst performance remains stable, reflecting the advantage of using high temperature resistant lanthanum manganate perovskite as a carrier to protect the active sites. Example 2 with x of 0.3 has the best comprehensive performance, and can reach more than 90% NH 3 Conversion rate, more than 95% N 2 Selective.

[0079] In summary, the present invention provides a Cu-doped lanthanum manganate perovskite catalyst and a preparation method thereof, and the Cu-doped lanthanum manganate perovskite catalyst is applied to ammonia catalytic combustion at high ammonia concentration and high temperature. The preparation process is simple and convenient, and no precious metals are used. The prepared catalyst retains the high-temperature resistant structure of the perovskite while uniformly dispersing Cu, thereby avoiding the problem of easy sintering of the active components of the traditional catalyst. Under the high ammonia concentration of 20% and the high temperature test conditions of 77-1077°C, this Cu-doped perovskite material performs well, and the best performing sample can achieve more than 90% NH at 300°C. 3 Conversion rate, more than 95% N 2 Selective.

[0080] The above contents are only for explaining the technical idea of ​​the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. A Cu-doped lanthanum manganate perovskite catalyst, characterized in that: The chemical formula of the Cu-doped lanthanum manganate perovskite catalyst is LaMn 1-x Cu x O3; wherein x is 0.1 to 0.

5.

2. A method for preparing a Cu-doped lanthanum manganate perovskite catalyst, characterized in that: include: According to the chemical formula LaMn 1-x Cu x The molar ratio between lanthanum, manganese and copper in O3 is as follows: lanthanum nitrate, manganese acetate and copper nitrate are weighed; wherein x is 0.1 to 0.5; Dissolving lanthanum nitrate, manganese acetate, copper nitrate and citric acid in deionized water to obtain a mixed solution; The mixed solution is heated to obtain a gel, the gel is dried to obtain a solid powder, and the solid powder is ground and calcined to obtain a Cu-doped lanthanum manganate perovskite catalyst.

3. The method for preparing a Cu-doped lanthanum manganate perovskite catalyst according to claim 2, characterized in that: The method of dissolving lanthanum nitrate, manganese acetate, copper nitrate and citric acid in deionized water to obtain a mixed solution comprises: dissolving lanthanum nitrate, manganese acetate and copper nitrate in deionized water to obtain a first solution; dissolving citric acid in deionized water to obtain a second solution; and mixing the first solution and the second solution to obtain a mixed solution.

4. The method for preparing a Cu-doped lanthanum manganate perovskite catalyst according to claim 2 or 3, characterized in that: The molar ratio of the total amount of the lanthanum nitrate, manganese acetate and copper nitrate to citric acid is 1:0.6-1.

5. The method for preparing a Cu-doped lanthanum manganate perovskite catalyst according to claim 2, characterized in that: The step of heating the mixed solution to obtain a gel comprises: The mixed solution is heated in a water bath at 50-60° C. and stirred for 1-2 hours to obtain a gel.

6. The method for preparing a Cu-doped lanthanum manganate perovskite catalyst according to claim 2, characterized in that: The step of drying the gel into a solid powder comprises: The gel is dried at 60-80° C. for 18-20 hours to obtain a solid powder.

7. The method for preparing a Cu-doped lanthanum manganate perovskite catalyst according to claim 2, characterized in that: When the solid powder is ground and then calcined, the heating rate of the calcination is 10-15°C / min, and the calcination is continued at 800-1000°C for 5-6 hours before cooling to room temperature.

8. The method for preparing a Cu-doped lanthanum manganate perovskite catalyst according to claim 2, characterized in that: The x is 0.

3.

9. A Cu-doped lanthanum manganate perovskite catalyst, characterized in that: The catalyst is prepared by the method for preparing the Cu-doped lanthanum manganate perovskite catalyst according to any one of claims 2 to 8.

10. Use of the Cu-doped lanthanum manganate perovskite catalyst as claimed in claim 1 or 9 in ammonia catalytic combustion.

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