Catalyst la for catalytic combustion of low concentrations of methane 1-y Ce y Mn 1-x Fe x O 3+δ and a method for its production

Abstract

Embodiments of the present application provide a catalyst La 1‑y Ce y Mn 1‑x Fe x O 3+δ and a preparation method thereof, and belong to the field of catalytic combustion of methane. The catalyst La 1‑y Ce y Mn 1‑x Fe x O 3+δ has a perovskite structure of ABO3, wherein A is La and Ce elements, B is Mn and Fe elements, x is 0.05-0.3, y is 0.05-0.3, and δ represents a natural number of non-stoichiometric vacancies of oxygen. In the present application, by using a sol-gel method to respectively dope Ce and Fe into A and B site cations of the ABO3 type perovskite structure, the mole ratio of La to Ce and the mole ratio of Mn to Fe are adjusted to control the surface properties of the perovskite, so as to improve the catalytic activity of the perovskite type catalyst, and make it have excellent resistance to water vapor and sulfur resistance and anti-poisoning performance.

Description

[0001] Cross-references to related applications

[0002] This application claims priority to earlier application 202510033201.X, filed on January 9, 2025, which is incorporated herein by reference in its entirety. Technical Field

[0003] This invention belongs to the field of methane catalytic combustion, and particularly relates to a catalyst La for the catalytic combustion of low-concentration methane. 1-y Ce y Mn 1-x Fe x O 3+δ And its preparation method. Background Technology

[0004] In today's world, energy use remains dominated by the three traditional energy sources: oil, natural gas, and coal. These energy sectors account for approximately 40% of total methane emissions caused by human activities. Methane's greenhouse effect is 23 to 28 times that of carbon dioxide, and it is considered a "super greenhouse gas." In particular, low-concentration methane is produced during coal mining, with methane content ranging from 0.1% to 1%, but the amount emitted is enormous. If large quantities of methane are allowed to be directly released into the atmosphere, it will exacerbate global climate change and cause significant environmental damage. Therefore, to protect the environment, it is necessary to appropriately convert and utilize the low-concentration methane produced from coal mining.

[0005] One way to convert and utilize methane is through combustion, transforming it into harmless substances. Flame combustion and catalytic combustion are the two main methods of methane combustion. The activation energy of the CH bond within the methane molecule is as high as 435 kJ / mol, meaning that achieving complete combustion of methane requires a considerable amount of energy. However, traditional flame combustion exhibits problems such as extremely high combustion temperatures, high nitrogen oxide emissions, and low energy efficiency, failing to meet the requirements of current socio-economic development and environmental protection. Against this backdrop, catalytic combustion of methane has received extensive attention and research. Catalytic combustion of methane refers to the oxidation reaction of methane with oxygen at a relatively low temperature under the action of a catalyst, producing carbon dioxide and water and releasing a large amount of heat. Compared to traditional flame combustion, catalytic combustion of methane has advantages such as lower operating temperatures, higher combustion efficiency, lower pollutant emissions, lower methane concentration requirements, and a stable and controllable combustion process, thus being considered a highly attractive alternative to traditional flame combustion.

[0006] Catalyst is the core of methane catalytic combustion technology, and its performance directly affects the efficiency and stability of catalytic reaction. At present, the common methane catalytic combustion catalysts mainly include two categories of noble metal catalysts and non-noble metal oxide catalysts. The noble metal catalysts take Pd, Pt and Rh as active components, have excellent low-temperature activity, but also have disadvantages of easy deactivation, easy poisoning and high cost. The non-noble metal oxide catalysts take metal oxides or composite oxides as main components, such as perovskite, hexaaluminate, etc., have advantages of low cost and high stability, but have poor low-temperature activity. The low-concentration methane mixed gas generated in the process of coal mining has complex components, usually contains certain water vapor and sulfur components, which can significantly affect the activity of the catalyst and cause poisoning, which has a very adverse effect on the actual application. The perovskite catalyst with the chemical formula ABO3 as the intrinsic structure is considered as a potential substitute for the methane combustion catalyst due to its controllable coordination environment, surface properties and special structure. In the chemical formula ABO3, the A-site cation is usually a rare earth element, and the B-site cation is a transition metal element. In addition, the perovskite catalyst has the advantages of low cost and excellent stability in the actual treatment of low-concentration methane.

[0007] Mg 2+ can be introduced into LaMnO3 perovskite by a sol-gel method, wherein, due to the introduction of Mg 2+ , which replaces part of the Mn sites, it is beneficial to the activation and dissociation of the C-H bond of methane and accelerates the complete oxidation of methane. However, the complete conversion temperature of the above-mentioned perovskite catalyst for methane is still relatively high.

[0008] For another example, Chinese patent publication CN 107362791B discloses a non-stoichiometric perovskite-type Y 1-x In 1-y O 3+δ methane catalytic combustion catalyst, which increases the specific surface area, high-temperature thermal stability, defect sites and catalytic activity by controlling the burning and volatilization speed of glycine fuel and the non-stoichiometric doping at A or B sites, but does not consider the negative effects of water vapor and sulfides on the catalyst. Therefore, it is particularly important to realize the high low-temperature activity and anti-poisoning performance of the perovskite catalyst through a simple surface regulation method.

[0009] Therefore, the present application provides a new catalyst La 1- y Ce y Mn 1-x Fe x O 3+δ and a preparation method thereof. SUMMARY

[0010] To solve at least one aspect of the above problems and defects in the prior art, embodiments of the present application provide a catalyst La 1-y Ce y Mn 1-x Fe x O 3+δ and a preparation method thereof, which can be prepared by doping metal elements Ce and Fe into A and B site cations of an ABO3 type perovskite structure respectively by using a sol-gel method, and adjusting the molar ratio of metal elements La and Ce, and Mn and Fe, to regulate the surface properties of the perovskite, so as to improve the catalytic activity of the perovskite type catalyst, and make it have excellent resistance to water vapor and sulfur poisoning performance, thereby overcoming the problem that the catalytic activity of the methane catalytic combustion catalyst in the prior art is relatively high at low temperature, and it is difficult to consider the resistance to SO2 and water vapor poisoning performance.

[0011] According to an aspect of the present application, a catalyst La 1- y Ce y Mn 1-x Fe x O 3+δ is provided for catalytic combustion of low concentration methane. 1-y Ce y Mn 1-x Fe x O 3+δ is a perovskite type ABO3 structure, wherein A site is La and Ce element, B site is Mn and Fe element, x is 0.05-0.3, y is 0.05-0.3, and δ represents the natural number of non-stoichiometric vacancies of oxygen.

[0012] Optionally, in the catalyst La 1-y Ce y Mn 1-x Fe x O 3+δ ,

[0013] x is 0.1, y is 0.05;

[0014] x is 0.1, y is 0.15;

[0015] x is 0.1, y is 0.2;

[0016] x is 0.1, y is 0.25; or

[0017] x is 0.1, y is 0.3.

[0018] In another aspect, the present application provides a preparation method of a catalyst La 1-y Cey Mn 1- x Fe x O 3+δ , wherein the method comprises the steps of:

[0019] La 1-y Ce y Mn 1-x Fe x O 3+δ a desired ratio of the molar amounts of the metal elements, wherein x is 0.05-0.3 and y is 0.05-0.3, nitrate salts of La, Ce, Mn and Fe are weighed respectively and dissolved in water to obtain a nitrate salt solution;

[0020] citric acid is weighed so that the total molar amount of all La, Ce, Mn and Fe ions: the molar amount of citric acid = 1:1.2;

[0021] the nitrate salt solution is heated at a constant temperature and stirred, then glycol and the citric acid are added to obtain a mixed solution, and then the mixed solution is heated, stirred and evaporated to form a gel;

[0022] the gel is dried to obtain an intermediate; and

[0023] the intermediate is calcined to obtain the catalyst La 1-y Ce y Mn 1-x Fe x O 3+δ .

[0024] In some embodiments, in the step of heating at a constant temperature and stirring, a water bath heating device can be used, the nitrate salt solution can be heated at a constant temperature and stirred uniformly at a temperature range of 70-90°C; the glycol and the citric acid can be added after uniform stirring for 5-15 min; and the mixed solution can be heated, stirred and evaporated at a temperature range of 70-90°C using the water bath heating device.

[0025] Further, in some embodiments, in the step of heating at a constant temperature and stirring, the nitrate salt solution can be heated at a constant temperature and stirred uniformly at 80°C; the glycol and the citric acid can be added after uniform stirring for 10 min; and the mixed solution can be heated, stirred and evaporated at 80°C.

[0026] In some embodiments, in the drying step, an oven can be used, and the gel can be dried at a temperature of 100-120°C for 10-15 h.

[0027] Further, in some embodiments, in the drying step, the gel can be dried at 110℃ for 12h.

[0028] In some embodiments, in the calcination step, the intermediate can be moved into a muffle furnace, heated from room temperature to 500℃-900℃ at a heating rate of 4.9-5.1℃ / min, and calcined for 5h.

[0029] Further, in some embodiments, in the calcination step, it can be heated from room temperature to 800℃ at a heating rate of 5℃ / min, and calcined for 5h.

[0030] In some embodiments, the method for preparing a catalyst La 1- y Ce y Mn 1-x Fe x O 3+δ of the present application for catalytic combustion of low-concentration methane, by using a sol-gel method to dope Ce and Fe into the A and B site cations of the ABO3 type perovskite structure, respectively, and adjusting the molar ratio of La to Ce, and Mn to Fe, to regulate the surface properties of the catalyst La 1-y Ce y Mn 1-x Fe x O 3+δ .

[0031] The catalyst La 1-y Ce y Mn 1-x Fe x O 3+δ for catalytic combustion of low-concentration methane according to the embodiments of the present application, and the method for preparing the same, at least has at least one of the following advantages or part of one advantage:

[0032] First, the catalyst La 1-y Ce y Mn 1-x Fe x O 3+δIn the application, since Ce and Fe are co-doped, La and Ce are in A position, and Mn and Fe are in B position, and x is 0.05-0.3 and y is 0.05-0.3, the catalytic activity of the perovskite catalyst is improved. In addition, by doping Fe and Ce, Ce can be used as a sacrificial agent to reduce the sulfation of active sites and improve the sulfur resistance of the catalyst. Moreover, the co-doping of Ce and Fe can inhibit the further adsorption and dissociation of water molecules, thereby improving the water resistance of the catalyst, and achieving good water vapor resistance, sulfur resistance and anti-poisoning performance. Therefore, the application at least solves the problem that the low-temperature catalytic activity, SO2 and water vapor resistance and catalytic activity of the existing methane catalytic combustion catalyst are difficult to be considered.

[0033] Secondly, by doping Ce and Fe elements into A and B positions of ABO3 perovskite structure respectively through a sol-gel method, and adjusting the molar ratio of metal elements La and Ce, and metal elements Mn and Fe, x is 0.05-0.3 and y is 0.05-0.3, the surface properties of the perovskite are regulated, and the obtained catalyst La 1-y Ce y Mn 1-x Fe x O 3+δ The catalyst has a large specific surface area, a high Mn 4+ / Mn 3+ ratio, more oxygen vacancies, enhanced oxygen mobility, optimized methane combustion performance, significantly reduced combustion temperature and activation, low-temperature catalytic oxidation reaction, good low-temperature activity, and improved catalytic activity of the perovskite catalyst. BRIEF DESCRIPTION OF DRAWINGS

[0034] These and / or other aspects and advantages of the present application will become apparent and be more readily understood from the following description, taken in conjunction with the accompanying drawings, in which:

[0035] Figure 1 A flow chart of a method for preparing a catalyst La 1-y Ce y Mn 1-x Fe x O 3+δ for low-concentration methane catalytic combustion according to one embodiment of the application is schematically shown;

[0036] Figure 2 The perovskite catalyst La 0.8 Ce 0.2 Mn 0.9 Fe 0.1 O3+δ The XRD diffraction patterns of the catalysts in Comparative Example 1 and Comparative Example 3 are shown.

[0037] Figure 3 Show respectively Figure 2 La, a perovskite-type catalyst 0.8 Ce 0.2 Mn 0.9 Fe 0.1 O 3+δ XPS Mn 2p spectra of the catalysts in Comparative Examples 1 and 3 are compared with those in Comparative Example 3.

[0038] Figure 4 Show Figure 2 La, a perovskite-type catalyst 0.8 Ce 0.2 Mn 0.9 Fe 0.1 O 3+δ The three-cycle performance graph;

[0039] Figure 5 Show Figure 2 La, a perovskite-type catalyst 0.8 Ce 0.2 Mn 0.9 Fe 0.1 O 3+δ Thermal stability test results at 600℃ for 72 hours;

[0040] Figure 6 Show Figure 2 La, a perovskite-type catalyst 0.8 Ce 0.2 Mn 0.9 Fe 0.1 O 3+δ Stability test results of the catalysts in Comparative Example 1 and Comparative Example 3 at 500 °C and 10 vol% water vapor conditions, respectively.

[0041] Figure 7 Show Figure 2 La, a perovskite-type catalyst 0.8 Ce 0.2 Mn 0.9 Fe 0.1 O 3+δ Stability test results of the catalysts in Comparative Example 1 and Comparative Example 3 at 500 °C and 100 ppm SO2, respectively.

[0042] Figure 8 Show Figure 2 La, a perovskite-type catalyst 0.8 Ce 0.2 Mn 0.9 Fe0.1 O 3+δ Scanning electron micrograph of the sample. DETAILED DESCRIPTION

[0043] The technical solutions of the present application will be further described below through specific examples. The following description of the embodiments of the present application with reference to the accompanying drawings is intended to explain the general concept of the present application and should not be understood as a limitation of the present application.

[0044] At present, due to the characteristics of large air volume and drastic concentration change of low-concentration methane mixed gas generated in the process of coal mining, and the presence of a certain amount of water vapor and sulfide in the gas, these environmental factors can have a certain impact on the catalytic activity of the existing catalyst, resulting in the problem that the catalyst used for methane catalytic combustion in the prior art is difficult to balance the resistance to SO2, water vapor resistance and catalytic activity.

[0045] Therefore, the embodiments of the present application provide a new catalyst La 1- y Ce y Mn 1-x Fe x O 3+δ .

[0046] Further, the embodiments of the present application also provide a method for preparing the above-mentioned catalyst La 1-y Ce y Mn 1-x Fe x O 3+δ , which can be prepared by doping elements Ce and Fe into the A and B site cations of ABO3 type perovskite structure LaMnO3 respectively by using a sol-gel method, and adjusting the molar ratio of La to Ce and the molar ratio of Mn to Fe to control the surface properties of La 1-y Ce y Mn 1-x Fe x O 3+δ perovskite, optimize the methane combustion performance of the catalyst, significantly reduce the combustion temperature and activation, and be beneficial to the catalytic oxidation reaction at low temperature, have good low-temperature activity, improve the catalytic activity of the perovskite catalyst, and realize the improvement of the resistance to poisoning of the catalyst in terms of resistance to water vapor and resistance to sulfur. In addition, in this paper, "Ce and Fe co-doping" can be referred to as "Ce-Fe co-doping", and "Ce and Fe double doping" can be referred to as "Ce-Fe double doping".

[0047] Further, La is a rare earth element, as an A-site cation, it has a large ionic radius and an oxidation state of +3 (positive 3), which can effectively occupy the A-site of the perovskite structure of the catalyst La 1-y Ce y Mn 1-x Fe x O 3+δ , the relatively high electronegativity enables it to form stable compounds with oxygen in the reaction, enhancing the crystal stability of the catalyst. Mn is a common catalytically active component, with multiple oxidation states, such as Mn 2+ , Mn 3+ and Mn 4+ , its variable oxidation state enables it to exhibit excellent catalytic ability in redox reactions. The introduction of Mn not only improves the redox cycle efficiency of the catalyst, but also increases the active sites of the catalyst by promoting the reaction between oxygen and reactants. Fe, as a transition metal, has good electrical conductivity and multiple oxidation states, mainly +2 (positive 2) and +3 (positive 3), which can effectively promote electron transfer in catalytic reactions. After doping Fe, the electronic properties of the catalyst can be well regulated, improving the reaction rate and selectivity, and the presence of Fe helps to enhance the reaction activity of the catalyst. In addition, the wide application and low cost of Fe make it not only improve the performance of the catalyst, but also have good economic efficiency, suitable for industrial application. Ce, as a rare earth element, has excellent resistance to poisoning and good redox performance. In the presence of SO2, metal sulfates will inevitably form on the catalyst, and Ce can act as a sacrificial agent to reduce the sulfation of active sites, improving the sulfur resistance of the catalyst. In the presence of H2O, the main reason for the decrease in methane combustion activity on the catalyst surface is the competition between OH and gaseous adsorbed H2O for active sites, and doping with Fe and Ce can inhibit the further adsorption and dissociation of water molecules, thereby improving the water resistance of the catalyst. Therefore, the combination of La, Ce, Mn, and Fe can be suitable as a catalyst for low-concentration methane catalytic combustion.

[0048] According to one embodiment of the present application, a catalyst La 1- y Ce y Mn 1-x Fe x O 3+δ is provided for low-concentration methane catalytic combustion, wherein the catalyst La 1-y Ce y Mn 1-x Fe x O 3+δA site is La and Ce element, B site is Mn and Fe element, x is 0.05-0.3, y is 0.05-0.3, and δ represents a natural number of O (oxygen) non-stoichiometric vacancies.

[0049] Optionally, the catalyst La 1-y Ce y Mn 1-x Fe x O 3+δ , x is 0.1, y is 0.05; x is 0.1, y is 0.15; x is 0.1, y is 0.2; x is 0.1, y is 0.25; or x is 0.1, y is 0.3.

[0050] Referring to Figure 1 , a method for preparing a catalyst La 1-y Ce y Mn 1-x Fe x O 3+δ for low-concentration methane catalytic combustion according to another embodiment of the present application is shown, which includes the following steps:

[0051] According to the catalyst La 1-y Ce y Mn 1-x Fe x O 3+δ , the required molar ratio of metal elements, wherein x is 0.05-0.3, y is 0.05-0.3, the nitrate of La, Ce, Mn and Fe is weighed and dissolved in water to obtain a nitrate solution;

[0052] Citric acid is weighed so that the total molar amount of all La, Ce, Mn and Fe ions: citric acid = 1:1.2;

[0053] After constant temperature heating and stirring of the nitrate solution, ethylene glycol and the citric acid are added to obtain a mixed solution, and then the mixed solution is heated, stirred and evaporated to form a gel;

[0054] The gel is dried to obtain an intermediate; and

[0055] The intermediate is calcined to obtain the catalyst La 1-y Ce y Mn 1-x Fe x O 3+δ .

[0056] In some embodiments, in the step of constant temperature heating and stirring, a water bath heating device, such as a water bath kettle, can be used to heat and stir the nitrate solution at a constant temperature in the range of 70-90°C; the ethylene glycol and the citric acid can be added after 5-15 minutes of uniform stirring; and the mixed solution can be heated, stirred and evaporated at a temperature in the range of 70-90°C using the water bath heating device.

[0057] Further, in some embodiments, in the step of constant temperature heating and stirring, the nitrate solution can be heated at a constant temperature of 80°C while being stirred uniformly; the ethylene glycol and the citric acid can be added after 10 minutes of uniform stirring; and the mixed solution can be heated, stirred and evaporated at 80°C.

[0058] In some embodiments, in the step of drying, an oven can be used to dry the gel at a temperature in the range of 100-120°C for 10-15 hours.

[0059] Further, in some embodiments, in the step of drying, the gel can be dried at 110°C for 12 hours.

[0060] In some embodiments, in the step of calcination, the intermediate can be moved into a muffle furnace for calcination, heated from room temperature to 500-900°C at a heating rate of 4.9-5.1°C / min, and calcinated for 5 hours.

[0061] Further, in some embodiments, in the step of calcination, the intermediate can be heated from room temperature to 800°C at a heating rate of 5°C / min, and calcinated for 5 hours.

[0062] In some embodiments, the method for preparing a catalyst La 1- y Ce y Mn 1-x Fe x O 3+δ of the present application for low-concentration methane catalytic combustion can control the surface properties of the catalyst La 1-y Ce y Mn 1- x Fe x O 3+δ by doping Ce and Fe into the A and B site cations of the ABO3-type perovskite structure respectively using a sol-gel method, and adjusting the molar ratio of La to Ce and Mn to Fe.

[0063] In some embodiments, the water can include deionized water.

[0064] In some embodiments, after the drying step, the dried intermediate can be ground using a grinder.

[0065] In some embodiments, after the heating and calcination step, the catalyst La 1-y Ce y Mn 1- x Fe x O 3+δ , for example air cooling.

[0066] The following illustrates, by way of specific examples and comparative examples, a method for preparing a catalyst La 1-y Ce y Mn 1-x Fe x O 3+δ for catalytic combustion of low concentration methane.

[0067] Comparative Example One:

[0068] At room temperature, 0.01 mol of La(N03)3-6H20 and 0.01 mol of Mn(N03)2-4H20 were dissolved in 27 mL of deionized water to form a nitrate solution; then, the nitrate solution was transferred to a water bath at 80°C and heated and stirred for 10 min to ensure that the metal ions were fully dispersed in the solution. Next, citric acid was weighed so that the total molar amount of all La and Mn ions: citric acid = 1 : 1.2, and then the above-mentioned citric acid solid was slowly added to the nitrate solution, and an appropriate amount of ethylene glycol was added to reduce the segregation of metal ions and ensure uniform perovskite composition. Next, the mixed solution was continuously heated and stirred at 80°C until a solution was formed and further formed a gel; next, the obtained gel was placed in an oven at 110°C and dried for 12 h to obtain a dried intermediate. Finally, the above-mentioned dried intermediate was placed in a muffle furnace and heated from room temperature to 800°C at a heating rate of 5°C / min, and calcined at this temperature for 5 h to obtain a catalyst LaMn03.

[0069] Comparative Example Two:

[0070] At room temperature, 0.01 mol of La(N03)3-6H20, 0.0095 mol of Mn(N03)2-4H20 and 0.0005 mol of Fe(N03)3-9H20 were dissolved in 27 mL of deionized water to form a nitrate solution; then, the nitrate solution was transferred to a water bath at 80°C and heated and stirred for 10 min to ensure that the metal ions were fully dispersed in the solution. Next, citric acid was weighed so that the total number of moles of all La, Mn and Fe ions: citric acid = 1 : 1.2, and then the above-mentioned citric acid solid was slowly added to the nitrate solution, and an appropriate amount of ethylene glycol was added to reduce the segregation of metal ions, ensuring uniform composition in the perovskite. Next, the mixed solution was continuously heated and stirred at 80°C and evaporated until a solution was formed and further formed into a gel; next, the obtained gel was placed in an oven at 110°C and dried for 12 h to obtain a dried intermediate. Finally, the above-mentioned dried intermediate was placed in a muffle furnace, heated from room temperature to 800°C at a heating rate of 5°C / min, and calcined at this temperature for 5 h to obtain a catalyst LaMn 0.95 Fe 0.05 O 3+δ .

[0071] Comparative Example Three:

[0072] At room temperature, 0.01 mol of La(N03)3-6H20, 0.0095 mol of Mn(N03)2-4H20 and 0.0005 mol of Fe(N03)3-9H20 were dissolved in 27 mL of deionized water to form a nitrate solution; then, the nitrate solution was transferred to a water bath at 80°C and heated and stirred for 10 min to ensure that the metal ions were fully dispersed in the solution. Next, citric acid was weighed so that the total number of moles of all La, Mn and Fe ions: citric acid = 1 : 1.2, and then the above-mentioned citric acid solid was slowly added to the nitrate solution, and an appropriate amount of ethylene glycol was added to reduce the segregation of metal ions, ensuring uniform composition in the perovskite. Next, the mixed solution was continuously heated and stirred at 80°C and evaporated until a solution was formed and further formed into a gel; next, the obtained gel was placed in an oven at 110°C and dried for 12 h to obtain a dried intermediate. Finally, the above-mentioned dried intermediate was placed in a muffle furnace, heated from room temperature to 800°C at a heating rate of 5°C / min, and calcined at this temperature for 5 h to obtain a catalyst LaMn 0.9 Fe 0.1 O 3+δ .

[0073] Comparative Example Four:

[0074] At room temperature, 0.01 mol of La(N03)3-6H20, 0.0085 mol of Mn(N03)2-4H20 and 0.0015 mol of Fe(N03)3-9H20 were dissolved in 27 mL of deionized water to form a nitrate solution; then, the nitrate solution was transferred to a water bath at 80 °C and heated and stirred for 10 min to ensure that the metal ions were fully dispersed in the solution. Next, citric acid was weighed so that the total number of moles of all La, Mn and Fe ions: citric acid = 1 : 1.2, and then the above-mentioned citric acid solid was slowly added to the nitrate solution, and an appropriate amount of ethylene glycol was added to reduce the segregation of metal ions, ensuring uniform composition in the perovskite. Next, the mixed solution was continuously heated and stirred at 80 °C and evaporated until a solution was formed and further formed into a gel; next, the obtained gel was placed in an oven at 110 °C and dried for 12 h to obtain a dried intermediate. Finally, the above-mentioned dried intermediate was placed in a muffle furnace, heated from room temperature to 800 °C at a heating rate of 5 °C / min, and calcined at this temperature for 5 h to obtain a catalyst LaMn 0.85 Fe 0.15 O 3+δ .

[0075] Comparative Example Five:

[0076] At room temperature, 0.01 mol of La(N03)3-6H20, 0.0085 mol of Mn(N03)2-4H20 and 0.0015 mol of Fe(N03)3-9H20 were dissolved in 27 mL of deionized water to form a nitrate solution; then, the nitrate solution was transferred to a water bath at 80 °C and heated and stirred for 10 min to ensure that the metal ions were fully dispersed in the solution. Next, citric acid was weighed so that the total number of moles of all La, Mn and Fe ions: citric acid = 1 : 1.2, and then the above-mentioned citric acid solid was slowly added to the nitrate solution, and an appropriate amount of ethylene glycol was added to reduce the segregation of metal ions, ensuring uniform composition in the perovskite. Next, the mixed solution was continuously heated and stirred at 80 °C and evaporated until a solution was formed and further formed into a gel; next, the obtained gel was placed in an oven at 110 °C and dried for 12 h to obtain a dried intermediate. Finally, the above-mentioned dried intermediate was placed in a muffle furnace, heated from room temperature to 800 °C at a heating rate of 5 °C / min, and calcined at this temperature for 5 h to obtain a catalyst LaMn 0.8 Fe 0.2 O 3+δ .

[0077] Comparative Example Six:

[0078] At room temperature, 0.01 mol of La(N03)3-6H20, 0.007 mol of Mn(N03)2-4H20 and 0.003 mol of Fe(N03)3-9H20 were dissolved in 27 mL of deionized water to form a nitrate solution; then, the nitrate solution was transferred to a water bath at 80°C and heated and stirred for 10 min to ensure that the metal ions were fully dispersed in the solution. Next, citric acid was weighed so that the total number of moles of all La, Mn and Fe ions: citric acid = 1 : 1.2, and then the above-mentioned citric acid solid was slowly added to the nitrate solution, and an appropriate amount of ethylene glycol was added to reduce the segregation of metal ions, ensuring uniformity of the perovskite composition. Next, the mixed solution was continuously heated and stirred at 80°C and evaporated until a solution was formed and further formed into a gel; next, the obtained gel was placed in an oven at 110°C and dried for 12 h to obtain a dried intermediate. Finally, the above-mentioned dried intermediate was placed in a muffle furnace, heated from room temperature to 800°C at a heating rate of 5°C / min, and calcined at this temperature for 5 h to obtain a catalyst LaMn 0.7 Fe 0.3 O 3+δ .

[0079] Example One:

[0080] At room temperature, 0.0095 mol of La(N03)3-6H20, 0.0005 mol of Ce(N03)3-6H20, 0.009 mol of Mn(N03)2-4H20 and 0.001 mol of Fe(N03)3-9H20 were dissolved in 27 mL of deionized water to form a nitrate solution; then, the nitrate solution was transferred to a water bath at 80°C and heated and stirred for 10 min to ensure that the metal ions were fully dispersed in the solution. Next, citric acid was weighed so that the total number of moles of all La, Ce, Mn and Fe ions: citric acid = 1 : 1.2, and then the above-mentioned citric acid solid was slowly added to the nitrate solution, and an appropriate amount of ethylene glycol was added to reduce the segregation of metal ions, ensuring uniformity of the perovskite composition. Next, the mixed solution was continuously heated and stirred at 80°C and evaporated until a solution was formed and further formed into a gel; next, the obtained gel was placed in an oven at 110°C and dried for 12 h to obtain a dried intermediate. Finally, the above-mentioned dried intermediate was placed in a muffle furnace, heated from room temperature to 800°C at a heating rate of 5°C / min, and calcined at this temperature for 5 h to obtain a catalyst La 0.95 Ce 0.05 Mn 0.9 Fe 0.1 O 3+δ .

[0081] Example Two:

[0082] At room temperature, 0.009 mol of La(N03)3-6H20, 0.001 mol of Ce(N03)3-6H20, 0.009 mol of Mn(N03)2-4H20, and 0.001 mol of Fe(N03)3-9H20 were dissolved in 27 mL of deionized water to form a nitrate solution; then, the nitrate solution was transferred to a water bath at 80 °C and heated and stirred for 10 min to ensure that the metal ions were well dispersed in the solution. Next, citric acid was weighed so that the total number of moles of all La, Ce, Mn, and Fe ions: citric acid = 1 : 1.2, and then the above-mentioned citric acid solid was slowly added to the nitrate solution, and an appropriate amount of ethylene glycol was added to reduce the segregation of metal ions and ensure uniform perovskite composition. Next, the mixed solution was continuously heated and stirred at 80 °C and evaporated until a solution was formed and further formed into a gel; next, the obtained gel was placed in an oven at 110 °C and dried for 12 h to obtain a dried intermediate. Finally, the above-mentioned dried intermediate was placed in a muffle furnace, heated from room temperature to 800 °C at a heating rate of 5 °C / min, and calcined at this temperature for 5 h to obtain a catalyst La 0.9 Ce 0.1 Mn 0.9 Fe 0.1 O 3+δ .

[0083] Example Three:

[0084] At room temperature, 0.009 mol of La(N03)3-6H20, 0.001 mol of Ce(N03)3-6H20, 0.009 mol of Mn(N03)2-4H20, and 0.001 mol of Fe(N03)3-9H20 were dissolved in 27 mL of deionized water to form a nitrate solution; then, the nitrate solution was transferred to a water bath at 80 °C and heated and stirred for 10 min to ensure that the metal ions were well dispersed in the solution. Next, citric acid was weighed so that the total number of moles of all La, Ce, Mn, and Fe ions: citric acid = 1 : 1.2, and then the above-mentioned citric acid solid was slowly added to the nitrate solution, and an appropriate amount of ethylene glycol was added to reduce the segregation of metal ions and ensure uniform perovskite composition. Next, the mixed solution was continuously heated and stirred at 80 °C and evaporated until a solution was formed and further formed into a gel; next, the obtained gel was placed in an oven at 110 °C and dried for 12 h to obtain a dried intermediate. Finally, the above-mentioned dried intermediate was placed in a muffle furnace, heated from room temperature to 800 °C at a heating rate of 5 °C / min, and calcined at this temperature for 5 h to obtain a catalyst La 0.85 Ce 0.15 Mn 0.9 Fe 0.1 O3+δ .

[0085] Example Four:

[0086] At room temperature, 0.008 mol of La(N03)3-6H20, 0.002 mol of Ce(N03)3-6H20, 0.009 mol of Mn(N03)2-4H20 and 0.001 mol of Fe(N03)3-9H20 were dissolved in 27 mL of deionized water to form a nitrate solution; then, the nitrate solution was transferred to a water bath at 80 °C and heated and stirred for 10 min to ensure that the metal ions were fully dispersed in the solution. Next, citric acid was weighed so that the total number of moles of all La, Ce, Mn and Fe ions: citric acid = 1 : 1.2, and then the above-mentioned citric acid solid was slowly added to the nitrate solution, and an appropriate amount of ethylene glycol was added to reduce the segregation of metal ions and ensure uniform perovskite composition. Next, the mixed solution was continuously heated and stirred at 80 °C and evaporated until a solution was formed and further formed into a gel; next, the obtained gel was placed in an oven at 110 °C and dried for 12 h to obtain a dried intermediate. Finally, the above-mentioned dried intermediate was placed in a muffle furnace, heated from room temperature to 800 °C at a heating rate of 5 °C / min, and calcined at this temperature for 5 h to obtain a catalyst La 0.8 Ce 0.2 Mn 0.9 Fe 0.1 O 3+δ .

[0087] Example Five:

[0088] At room temperature, 0.0075 mol of La(N03)3-6H20, 0.0025 mol of Ce(N03)3-6H20, 0.009 mol of Mn(N03)2-4H20 and 0.001 mol of Fe(N03)3-9H20 were dissolved in 27 mL of deionized water to form a nitrate solution; then, the nitrate solution was transferred to a water bath at 80 °C and heated and stirred for 10 min to ensure that the metal ions were fully dispersed in the solution. Next, citric acid was weighed so that the total number of moles of all La, Ce, Mn and Fe ions: citric acid = 1 : 1.2, and then the above-mentioned citric acid solid was slowly added to the nitrate solution, and an appropriate amount of ethylene glycol was added to reduce the segregation of metal ions and ensure uniform perovskite composition. Next, the mixed solution was continuously heated and stirred at 80 °C and evaporated until a solution was formed and further formed into a gel; next, the obtained gel was placed in an oven at 110 °C and dried for 12 h to obtain a dried intermediate. Finally, the above-mentioned dried intermediate was placed in a muffle furnace, heated from room temperature to 800 °C at a heating rate of 5 °C / min, and calcined at this temperature for 5 h to obtain a catalyst La0.75 Ce 0.25 Mn 0.9 Fe 0.1 O 3+δ .

[0089] Example Six:

[0090] At room temperature, 0.007 mol of La(N03)3-6H20, 0.003 mol of Ce(N03)3-6H20, 0.009 mol of Mn(N03)2-4H20 and 0.001 mol of Fe(N03)3-9H20 were dissolved in 27 mL of deionized water to form a nitrate solution; then, the nitrate solution was transferred to a water bath at 80 °C and heated and stirred for 10 min to ensure that the metal ions were well dispersed in the solution. Next, citric acid was weighed so that the total molar amount of all La, Ce, Mn and Fe ions: citric acid = 1 : 1.2, and then the above-mentioned citric acid solid was slowly added to the nitrate solution, and an appropriate amount of ethylene glycol was added to reduce the segregation of metal ions and ensure uniform perovskite composition. Next, the mixed solution was continuously heated and stirred at 80 °C and evaporated until a solution was formed and further formed into a gel; next, the obtained gel was placed in an oven at 110 °C and dried for 12 h to obtain a dried intermediate. Finally, the above-mentioned dried intermediate was placed in a muffle furnace and heated from room temperature to 800 °C at a heating rate of 5 °C / min, and calcined at this temperature for 5 h to obtain a catalyst La 0.7 Ce 0.3 Mn 0.9 Fe 0.1 O 3+δ .

[0091] Then, the performance of the obtained above-mentioned catalysts was tested. For example, the catalytic performance can be tested in a normal pressure fixed bed reactor, and 400 mg of catalyst can be used, for example, 40-60 mesh. Before each test, the reactor can be heated to 300 °C at a heating rate of 10 °C / min and kept for 30 min under the atmosphere of N2 input at a flow rate of 200 mL / min to remove water and impurities that can be adsorbed on the catalyst. Then, the reaction gas including 1% CH4, 20% O2 and balance N2 can be introduced into the reactor at a flow rate of 100 mL / min. In order to record the ignition curve, the catalyst bed can be further heated to 700 °C at a heating rate of 10 °C / min. The outlet gas can be monitored online by an infrared methane online monitor, for example, FQ-1150E.

[0092] After testing, the catalyst La 1-y Ce y Mn1-x Fe x O 3+δ The comparative results of the catalytic combustion activity tests of the catalysts La 10 Ce 50 Mn 90 Fe 100 O 10 and the comparative examples 1 to 6 are shown in Table 1. In Table 1, T 50 , T 90 , T 100 and T 1-y are defined as the temperatures corresponding to the methane conversion rates of 10%, 50%, 90% and 100%, respectively. As shown in Table 1, according to the temperature comparison of T y , T 1-x , T x , T 3+δ , the catalytic combustion temperature of the catalyst La 10 Ce 0.8 Mn 0.2 Fe 0.9 O 0.1 in the examples 1 to 6 is obviously lower than that in the comparative examples 1 to 6, and the catalytic combustion activity of the former is relatively stronger. For example, when T 3+δ is 351℃, which is obviously lower than the catalytic combustion temperature of 377℃ to 395℃ using the catalysts in the comparative examples 1 to 6. For another example, when T 100 is 500℃, which is obviously lower than the catalytic combustion temperature of 542℃ to 648℃ using the catalysts in the comparative examples 1 to 6. The comparative results are shown in Table 1. 0.8 Ce 0.2 Mn 0.9 Fe 0.1 O 3+δ

[0093] The comparative results of the catalytic combustion activity of the catalysts La

[0094]

[0095] Hereinafter, the performance tests of the catalyst La 1-y Ce y Mn 1-x Fe x O 3+δ are further illustrated in detail by taking the example 4 in an embodiment of the present application as an example. ​

[0096] Figure 2 Catalyst La according to Example 4 of the present invention is shown respectively. 0.8 Ce 0.2 Mn 0.9 Fe 0.1 O 3+δ The XRD diffraction patterns of the catalysts are compared with those of Comparative Example 1 and Comparative Example 3. For example... Figure 2 As shown, the perovskite catalyst La according to Example 4 above of the present invention 0.8 Ce 0.2 Mn 0.9 Fe 0.1 O 3+δ Peak performance ratio of perovskite catalysts LaMnO3 and LaMn 0.9 Fe 0.1 O 3+δ The size is small, therefore, according to the perovskite-type catalyst La of Example 4 above, the present invention... 0.8 Ce 0.2 Mn 0.9 Fe 0.1 O 3+δ The crystallinity is higher than that of perovskite catalysts LaMnO3 and LaMn 0.9 Fe 0.1 O 3+δ The crystallinity is low, but the catalytic activity is strong. As some studies have shown, particles with lower crystallinity can improve catalytic performance. As the A and B sites of the catalyst LaMnO3 are gradually substituted, the crystallinity not only decreases, but the grain size also gradually decreases, and the CH4 catalytic activity gradually increases. This is because catalysts with smaller grain sizes have a larger surface area, thus providing more active sites and promoting more CH4 adsorption and cracking. Similarly, tests have shown that the perovskite-type catalysts LaMnO3 in Examples 1 to 3 and Examples 5 and 6 of some embodiments of the present invention exhibit high crystallinity. 1-y Ce y Mn 1-x Fe x O 3+δ They also exhibit similar performance trends. Therefore, the above examples demonstrate that the perovskite-type catalyst La according to the present invention... 1-y Ce y Mn 1- x Fe x O 3+δ Due to the co-doping of Ce and Fe, with La and Ce elements at the A site and Mn and Fe elements at the B site, the catalytic activity of the perovskite catalyst is improved under the conditions that x is 0.05–0.3 and y is 0.05–0.3.

[0097] Furthermore, Figure 3 Show respectively Figure 2perovskite catalyst La 0.8 Ce 0.2 Mn 0.9 Fe 0.1 O 3+δ XPS Mn 2p spectra of the catalysts of Example 1 and Comparative Examples 1 and 3. The surface Mn 4+ / Mn 3+ ratio trends for La 0.8 Ce 0.2 Mn 0.9 Fe 0.1 O 3+δ (0.41)>LaMn 0.9 Fe 0.1 O 3+δ (0.17)>LaMnO3(0.15), wherein the Mn 0.8 Ce 0.2 Mn 0.9 Fe 0.1 O 3+δ of La 4+ / Mn 3+ ratio is 0.41, the Mn 0.9 Fe 0.1 O 3+δ of LaMn 4+ / Mn 3+ ratio is 0.17, and the Mn 4+ / Mn 3+ ratio of LaMnO3is 0.15. Compared with LaMnO3, the content of Mn 0.9 Fe 0.1 O 3+δ of La 4+ Mn 0.8 Ce 0.2 Mn 0.9 Fe 0.1 O 3+δ has the highest Mn 4+ / Mn 3+ ratio, which not only indicates that doping an appropriate amount of Fe is conducive to the formation of Mn 4+ , but also may be because Ce has the effect of weakening the Mn-O bond, generating unstable Mn 3+ , thereby again promoting the generation of Mn 4+ . Higher surface Mn 4+ / Mn 3+ ratio is conducive to enhancing the Mn 3+ and Mn 4+oxidation-reduction cycle process, increases oxygen vacancies in the catalyst, which is conducive to the adsorption and activation of oxygen in the gas phase and the migration of lattice oxygen, thereby improving the catalytic activity of methane combustion. Similarly, tests show that the perovskite-type catalysts La 1-y Ce y Mn 1-x Fe x O 3+δ also exhibit similar performance trends. Therefore, the above examples further demonstrate that the perovskite-type catalysts La 1-y Ce y Mn 1-x Fe x O 3+δ Since Ce and Fe co-doping is used, in which the A site is La and Ce elements and the B site is Mn and Fe elements, under the condition that x is 0.05-0.3 and y is 0.05-0.3, the catalytic activity of the perovskite-type catalyst is improved.

[0098] Figure 4 show Figure 2 the perovskite-type catalyst La 0.8 Ce 0.2 Mn 0.9 Fe 0.1 O 3+δ after three cycles. As Figure 4 shown, the catalyst La 0.8 Ce 0.2 Mn 0.9 Fe 0.1 O 3+δ of Example Four of the present application does not show a downward trend in catalytic performance after three cycles, indicating that the catalyst has good cycle stability; moreover, the catalyst La 0.8 Ce 0.2 Mn 0.9 Fe 0.1 O 3+δ achieved complete conversion of methane at 500°C. Further, tests show that the inventors found that the activation energy of the catalyst of Example Four is 96.51 kJ / mol, which is lower than the activation energy of 109.60 kJ / mol of Comparative Example One and 105.64 kJ / mol of Comparative Example Three. Similarly, tests show that the perovskite-type catalysts according to Examples One to Three and Examples Five and Six in the embodiments of the present application also exhibit similar performance trends.

[0099] In summary, through research and testing of Fe and Ce doping of LaMnO3-based perovskite, the inventors found that, compared to the prior art, the catalyst La 1-y Ce y Mn1-x Fe x O 3+δ , the perovskite catalysts have good cycle stability.

[0100] Figure 5 The perovskite catalyst La Figure 2 0.8 Ce 0.2 Mn 0.9 Fe 0.1 O 3+δ The thermal stability test diagram under the condition of 600℃ and 72h. As shown in Figure 5 0.8 Ce 0.2 Mn 0.9 Fe 0.1 O 3+δ During the process of heating at high temperature of 600℃ for 72h, the generally horizontal straight line shows that the conversion rate remains stable and almost no obvious change occurs, which shows good thermal stability. Similarly, it is tested that the perovskite catalysts La 1-y Ce y Mn 1-x Fe x O 3+δ , the perovskite catalysts have good thermal stability.

[0101] Figure 6 The perovskite catalyst La Figure 2 0.8 Ce 0.2 Mn 0.9 Fe 0.1 O 3+δ The stability test diagram of the catalysts in Comparative Example One and Comparative Example Three under the condition of 500℃ and 10vol% water vapor respectively. In Figure 6 , “10vol% H2O on” means that the water vapor of 10vol% H2O is started to be introduced, and “10vol% H2O off” means that the water vapor of 10vol% H2O is closed or ended to be introduced. Compared with the activity under dry condition, the catalytic activity of the perovskite catalyst LaMnO3 is reduced by about 20%, the catalytic activity of the perovskite catalyst LaMn 0.9 Fe 0.1 O 3+δ is reduced by 5%, and the catalytic activity of the perovskite catalyst La​​​0.8 Ce 0.2 Mn 0.9 Fe 0.1 O 3+δ The catalytic activity remained essentially unchanged. Similarly, tests showed that the perovskite catalysts in Examples 1 to 3 and Examples 5 and 6 of the embodiments of the present invention also exhibited similar performance. Therefore, the test results demonstrate that the Ce-Fe dual-doped perovskite catalyst La 1-y Ce y Mn 1-x Fe x O 3+δ When the A site is occupied by La and Ce elements, the B site by Mn and Fe elements, and the x and y values ​​are 0.05–0.3 and 0.05–0.3 respectively, it exhibits good resistance to water vapor.

[0102] Figure 7 Show Figure 2 La, a perovskite-type catalyst 0.8 Ce 0.2 Mn 0.9 Fe 0.1 O 3+δ Stability test results of the catalysts in Comparative Examples 1 and 3 at 500℃ and 100ppm SO2, respectively. Figure 5 As shown, the catalytic activity of the perovskite catalyst LaMnO3 decreased by approximately 43% after 20 hours. 0.9 Fe 0.1 O 3+δ The catalytic activity decreased by 12% after 20 hours, while the perovskite catalyst La 0.8 Ce 0.2 Mn 0.9 Fe 0.1 O 3+δ The decrease was only 8%. Similarly, tests conducted on the perovskite catalysts in Examples 1 to 3 and Examples 5 and 6 according to the embodiments of the present invention also showed similar performance. Therefore, the test results demonstrate that the catalyst La... 1-y Ce y Mn 1-x Fe x O 3+δ Under the conditions that the A site is composed of La and Ce elements, the B site is composed of Mn and Fe elements, and x is 0.05–0.3 and y is 0.05–0.3, Ce-Fe dual doping can improve the performance of perovskite catalysts La. 1-y Ce y Mn 1-x Fe x O 3+δ It has a positive effect on sulfur resistance.

[0103] Figure 8 A scanning electron microscope image of the perovskite catalyst La 0.8 Ce 0.2 Mn 0.9 Fe 0.1 O 3+δ A scanning electron microscope image of the perovskite catalyst La 0.8 Ce 0.2 Mn 0.9 Fe 0.1 O 3+δ The perovskite presents a rough and wrinkle-covered surface, has more pore channel structures, and produces abundant mesopore-macropore structures, increasing the specific surface area.

[0104] In summary, the catalyst La 1-y Ce y Mn 1- x Fe x O 3+δ and the preparation method thereof have at least one or part of the following advantages:

[0105] First, in the catalyst La 1-y Ce y Mn 1-x Fe x O 3+δ , since Ce and Fe co-doping is adopted, in which the A site is La and Ce elements, and the B site is Mn and Fe elements, and under the condition that x is 0.05-0.3 and y is 0.05-0.3, the catalytic activity of the perovskite catalyst is improved; and by doping the double metal elements Fe and Ce, not only can Ce act as a sacrificial agent to reduce the sulfation of active sites and improve the sulfur resistance of the catalyst, but also the double doping of the metal elements Ce and Fe can inhibit the further adsorption and dissociation of water molecules, thereby improving the water resistance of the catalyst, so as to achieve good water vapor and sulfur resistance and anti-poisoning performance, so that the present application at least overcomes the problem that the relative low-temperature catalytic activity of the methane catalytic combustion catalyst in the prior art is difficult to be compatible with the anti-poisoning performance and catalytic activity of SO2 and water vapor.

[0106] Second, by doping the elements Ce and Fe into the A and B site cations of the ABO3 type perovskite structure respectively by using the sol-gel method, and adjusting the molar ratio of the metal elements La and Ce, and the metal elements Mn and Fe, so that x is 0.05-0.3 and y is 0.05-0.3, the surface properties of the perovskite are regulated, so that the catalyst La 1-y Ce y Mn 1-x Fex O 3+δ The catalyst has a large specific surface area, a high Mn 4+ / Mn 3+ The ratio produces more oxygen vacancies, enhances the oxygen mobility, optimizes the methane combustion performance of the catalyst, significantly reduces the combustion temperature and activation, is conducive to the catalytic oxidation reaction at low temperature, has good low-temperature activity, and effectively improves the catalytic activity of the perovskite catalyst.

[0107] Although some embodiments of the general inventive concept have been exemplarily shown and described above, it will be understood by those of ordinary skill in the art that changes, substitutions and additions can be made to these embodiments without departing from the principles and spirit of the general inventive concept, and the scope of protection of the present application is defined by the claims and their equivalents.

Claims

1. A catalyst La 1-y Ce y Mn 1-x Fe x O 3+δ for use in catalytic combustion of low-concentration methane, characterized in that, The catalyst La 1-y Ce y Mn 1-x Fe x O 3+δ is a perovskite type AB03 structure, wherein A site is La and Ce element, B site is Mn and Fe element, x is 0.05~0.3, y is 0.05~0.3, and δ represents a natural number of oxygen non-stoichiometric vacancies. The catalyst La 1-y Ce y Mn 1-x Fe x O 3+δ The preparation method comprises the following steps: According to the catalyst La 1-y Ce y Mn 1-x Fe x O 3+δ The required molar ratio of metal elements, respectively, take the nitrate of La, Ce, Mn and Fe and dissolve in water to obtain a nitrate solution; The citric acid is weighed so that the total molar amount of all La, Ce, Mn and Fe ions: molar amount of citric acid = 1 : 1.2; After constant temperature heating and stirring of the nitrate solution, ethylene glycol and the citric acid are added to obtain a mixed solution, and then the mixed solution is heated, stirred and evaporated to form a gel; The gel is dried to obtain an intermediate; and calcining said intermediate, thereby obtaining said catalyst La 1-y Ce y Mn 1-x Fe x O 3+δ .

2. The catalyst of claim 1, wherein La 1-y Ce y Mn 1-x Fe x O 3+δ application in catalytic combustion of low concentration methane, characterized in that, In the catalyst La 1-y Ce y Mn 1-x Fe x O 3+δ among them, x is 0.1, y is 0.05; x is 0.1, y is 0.15; x is 0.1, y is 0.2; x is 0.1, y is 0.25; or x is 0.1, y is 0.

3.

3. The catalyst of claim 2, wherein La 1-y Ce y Mn 1-x Fe x O 3+δ application in catalytic combustion of low concentration methane, characterized in that, In the step of constant temperature heating and stirring, the nitrate solution is heated at a constant temperature and stirred uniformly at a temperature ranging from 70°C to 90°C by using a water bath heating device; After uniform stirring for 5-15 min, the ethylene glycol and the citric acid are added; The mixed solution is heated, stirred and evaporated at a temperature ranging from 70°C to 90°C by using the water bath heating device.

4. The catalyst of claim 3, wherein La 1-y Ce y Mn 1-x Fe x O 3+δ application in catalytic combustion of low concentration methane, characterized in that, In the step of constant temperature heating and stirring, the nitrate solution is heated at a constant temperature and stirred uniformly at 80°C; After uniform stirring for 10 min, the ethylene glycol and the citric acid are added; The mixed solution is heated, stirred and evaporated at 80°C.

5. The catalyst of claim 2, wherein La 1-y Ce y Mn 1-x Fe x O 3+δ application in catalytic combustion of low concentration methane, characterized in that, In the step of drying, the gel is dried at a temperature ranging from 100°C to 120°C for 10-15 h by using an oven.

6. The catalyst of claim 5, wherein La 1-y Ce y Mn 1-x Fe x O 3+δ application in catalytic combustion of low concentration methane, characterized in that, In the step of drying, the gel is dried at 110°C for 12 h.

7. The catalyst of claim 2, wherein La 1-y Ce y Mn 1-x Fe x O 3+δ application in catalytic combustion of low concentration methane, characterized in that, In the step of calcining, the intermediate is moved into a muffle furnace to be calcined, heated from room temperature to 500°C-900°C at a heating rate of 4.9-5.1°C / min, and calcined for 5 h.

8. The catalyst of claim 7, wherein La 1-y Ce y Mn 1-x Fe x O 3+δ application in catalytic combustion of low concentration methane, characterized in that, In the step of calcining, heated from room temperature to 800°C at a heating rate of 5°C / min, and calcined for 5 h.

9. The catalyst La according to any one of claims 1 to 8 1-y Ce y Mn 1-x Fe x O 3+δ application in catalytic combustion of low-concentration methane, characterized in that, The surface properties of the catalyst La 1-y Ce y Mn 1-x Fe x O 3+δ are regulated by doping Ce and Fe into the A and B site cations of the ABO3 type perovskite structure using a sol-gel method, and adjusting the molar ratio of La to Ce and Mn to Fe.

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