A catalyst for catalytic decomposition of N2O derived from Co-MOFs and a preparation method thereof

Abstract

The application relates to a Co-MOFs-derived catalyst for catalytic decomposition of N2O and a preparation method thereof, and belongs to the field of catalysis. Stable cobalt oxide catalysts are derived and synthesized by taking Co-MOFs as precursors and by regulating the types of precursors, the gas atmosphere of calcination, the temperature, the temperature rising rate, the time and the number of times. The catalyst is used for directly catalytically decomposing high-concentration N2O in tail gas discharged by enterprises such as nitric acid plants, adipic acid plants and caprolactam plants at medium and low temperatures, and has excellent N2O catalytic decomposition activity, thermal stability and tunability.

Description

Technical Field

[0001] This invention belongs to the field of catalyst materials and air pollution control technology, specifically relating to a catalyst derived from cobalt-based metal-organic frameworks (Co-MOFs) and its preparation method, which is used for the direct catalytic decomposition of high-concentration N2O in industrial tail gas emitted by nitric acid plants, adipic acid plants, caprolactam plants, etc. at medium and low temperatures, so as to achieve emission standards. Background Technology

[0002] Nitrous oxide (N₂O) is a colorless gas with a slightly sweet taste. Recent studies have found that N₂O is a significant greenhouse gas, with a global warming potential (GWP) 273 times that of CO₂ and 10 times that of CH₄. N₂O is the third largest greenhouse gas after CO₂ and CH₄. Its atmospheric lifetime is approximately 150 years. While chemically inert in the troposphere, although up to 90% can be decomposed in the stratosphere by photolysis from solar radiation, the remaining 10% can react with reactive atomic oxygen and be consumed, causing severe damage to the ozone layer. N₂O has become the leading ozone-depleting substance emitted by human activities. The reduction of N₂O and other greenhouse gases has received high attention and widespread concern.

[0003] Currently, N2O treatment methods mainly include cyclohexanol absorption oxidation, high-temperature thermal decomposition, direct catalytic decomposition, selective catalytic reduction, and one-step phenol production via benzene oxidation. Among these, direct catalytic decomposition is the most economical and effective technology due to its simple process route, low operating cost, high N2O conversion rate (>99%), and absence of secondary pollution. The catalyst is the core component of this technology.

[0004] Most of the catalysts reported in studies for the direct catalytic decomposition of N2O are cobalt-based catalysts with cobalt species as the main active component. Patent CN106964360A discloses a core-shell type catalyst for the catalytic decomposition of N2O. The active oxide core of this catalyst is composed of the active component Co3O4, accounting for 10–40 wt%, while the porous inert oxide shell is composed of SiO2-N. x O y , where N x O yIt is either ZrO2 or CeO2. Patent CN104624203B discloses a Pb-modified Co oxide-based N2O decomposition catalyst, wherein the catalyst is a composite of PbO and Co oxide matrix, with the PbO mass percentage ranging from 2.7 wt% to 21.7 wt%. Patent CN106799249A discloses a Co oxide / BaCO3 catalyst for N2O catalytic decomposition, using BaCO3 as a support, where Co oxides are mainly present on the surface of the BaCO3 support, forming a Co oxide-enriched shell. Patent CN102921454A discloses a monolithic BEA molecular sieve catalyst for the direct catalytic decomposition of N2O, using cordierite as a support and Fe and Co metal ion-modified BEA molecular sieves as the active component. In summary, the active components of the existing patented catalysts are mainly cobalt species, indicating that cobalt-based catalysts remain the mainstream direction for the direct catalytic decomposition of N2O. However, due to limitations in the types of cobalt precursors and preparation methods, the physicochemical properties of the prepared catalysts have not achieved a fundamental breakthrough, and their activity for the direct catalytic decomposition of N2O has not been significantly improved.

[0005] Metal-organic frameworks (MOFs) are a class of crystalline porous materials with a periodic network structure, formed by the self-assembly of inorganic metal centers (metal ions or metal clusters) and bridging organic ligands. Currently, tens of thousands of MOF materials with diverse topologies have been reported. These MOF materials possess a wide range of unique functions, characterized by large specific surface area, abundant porosity, ease of synthesis, good stability, ultra-low density, and flexibility. Using MOFs as precursors, calcination at high temperature and in a specific atmosphere can prepare MOF derivatives. This process not only retains the transition metal elements of the parent material and the essential elements for the catalytic system, such as C, H, O, and N, in its ligands, but also inherits the high specific surface area and abundant pore structure of its precursor MOFs. This is beneficial for the adsorption and catalysis of reactants, and the tunable pore size ensures high mass transfer and diffusion capabilities in the catalytic reaction. Furthermore, the diversity of MOF materials allows for the pre-selection or design of precursor MOF compositions and structures, effectively controlling the structure, morphology, and composition of derived metal oxides. This enables the regulation of their catalytic performance and the establishment of a structure-activity relationship between catalyst structure and properties. Moreover, metal oxides prepared using MOFs as precursors not only inherit the pore structure of the parent material, but their physicochemical properties, such as particle size, composition, specific surface area, pore volume, and low-temperature reduction performance, can be effectively controlled during the preparation process. Additionally, due to high-temperature treatment, these derivatives exhibit higher activity and stability, and can withstand more stringent reaction conditions.

[0006] Catalysts derived from cobalt-based metal-organic framework compounds with cobalt as the metal center have been applied in fields such as CO catalytic oxidation (Catalysis Communications, 2011, 12(10): 875-879), toluene catalytic oxidation (Industrial & Engineering Chemistry Research, 2020, 59(13): 5583-5590), organic pollutant degradation (Environmental Science & Technology, 2015, 49(4): 2350-2357), oxygen evolution reaction (Applied Surface Science, 2021, 560: 155035), and electrochemical energy storage (Coordination Chemistry Reviews, 2021, 438: 213872), but there are few reports on their application in the direct catalytic decomposition of N2O. Patent CN112138725A discloses a cobalt-based metal-organic framework-derived catalyst for the catalytic decomposition of N2O. A precursor with a zeolite imidazole ester framework structure is synthesized using 2-methylimidazole, a deprotonating agent, and a cobalt nitrate solution. The precursor is then pyrolyzed in an inert gas atmosphere to form a cobalt nanocomposite catalyst supported on porous carbon materials. However, this carbon-based catalyst is highly unstable in the N2O catalytic decomposition system because N2O catalytic decomposition generates O2. Under high-temperature conditions, O2 reacts with carbon, altering the physicochemical properties of the catalyst. Furthermore, the catalyst's properties change after use, and it may even become deactivated. In addition, if the catalyst is structurally molded, the reaction of O2 with carbon during use may destroy the carbon framework, causing the catalyst structure to collapse. Summary of the Invention

[0007] To address the technical problems existing in the prior art, this invention provides a method for preparing a catalyst for the catalytic decomposition of N2O derived from Co-MOFs. The catalyst prepared by this method can be used for the direct catalytic decomposition of high-concentration N2O in industrial exhaust gases emitted from nitric acid plants, adipic acid plants, caprolactam plants, etc., at medium and low temperatures, and exhibits excellent catalytic performance and strong stability.

[0008] This invention provides a method for preparing a catalyst derived from Co-MOFs for the catalytic decomposition of N2O, comprising the following steps:

[0009] (1) A certain amount of Co-MOF precursor is placed in a tube furnace and heated to a specific temperature at a certain heating rate under a certain gas atmosphere or vacuum conditions. It is then calcined at that temperature for a period of time, naturally cooled to room temperature, and the solid product is collected.

[0010] (2) The product of step (1) can be used directly as a catalyst; or the calcination conditions can be changed and multiple calcinations can be carried out to finally obtain N and C doped cobalt oxide catalyst.

[0011] In the above preparation method, the Co-MOF precursor in step (1) is a metal-organic framework compound with cobalt as the metal center. The metal-organic framework compound contains at least cobalt or other metals, and the ligand corresponding to the MOF contains N and C elements. The types of metal-organic framework compounds include, but are not limited to, isoreticular metal-organic frameworks, zeolitic imidazolate frameworks, metalials of institute lavoisier frameworks, pocket-channel frameworks, and coordination pillowed-layers.

[0012] In the above preparation method, the multiple calcinations mentioned in step (2) refer to calcinations performed once, twice, three times, etc., under different calcination conditions (including temperature and / or atmosphere, etc.), which is equivalent to a total of calcinations performed twice, three times, four times, etc.

[0013] In the above preparation method, the calcination gas atmosphere in step (1) or (2) is selected from one or more of vacuum conditions, inert gas, oxidizing gas, and reducing gas. The inert gas is selected from one or more of helium (He), argon (Ar), and nitrogen (N2); the oxidizing gas is selected from one or more of oxygen (O2), nitrogen dioxide (NO2), nitrous oxide (N2O), and carbon dioxide (CO2); and the reducing gas is selected from one or more of carbon monoxide (CO), hydrogen (H2), and ammonia (NH3).

[0014] In the above preparation method, at least one of the calcination cycles must be conducted in an atmosphere composed of inert and oxidizing gases, with the content of oxidizing gases ranging from 5% to 100%.

[0015] In the above preparation method, the heating rate ranges from 1 to 10 °C / min.

[0016] In the above preparation method, the calcination temperature range is 100–800℃.

[0017] In the above preparation method, the calcination time ranges from 0.5 to 10 hours.

[0018] Further optimization is needed for the single calcination: the calcination atmosphere is composed of inert and oxidizing gases, with the oxidizing gas content being 5-20%; the heating rate is 1-5℃ / min; the calcination temperature is 300-500℃; and the calcination time is 2-5 hours. For the double calcination: the first calcination atmosphere is inert gas or vacuum; the heating rate is 1-5℃ / min; the calcination temperature is 500-800℃; and the calcination time is 2-5 hours. The second calcination atmosphere is composed of inert and oxidizing gases, with the oxidizing gas content being 5-20%; the heating rate is 1-5℃ / min; the calcination temperature is 300-500℃; and the calcination time is 2-5 hours. For a total of 3 calcinations, the first calcination is carried out in an inert gas or vacuum environment, with a heating rate of 1–5 °C / min, a calcination temperature of 500–800 °C, and a calcination time of 2–5 hours. The second calcination is carried out in an atmosphere composed of inert and oxidizing gases, with the oxidizing gas content being 5–20%, with a heating rate of 1–5 °C / min, a calcination temperature of 300–500 °C, and a calcination time of 2–5 hours. The third calcination is carried out in an atmosphere composed of reducing and inert gases, with the reducing gas content being 5–20%, with a heating rate of 1–5 °C / min, a calcination temperature of 100–350 °C, and a calcination time of 0.5–2 hours.

[0019] It is used for the direct catalytic decomposition of high-concentration N2O in industrial tail gas emitted by nitric acid plants, adipic acid plants, caprolactam plants, etc. at medium and low temperatures. The reaction temperature range is 300-550℃, and the N2O treatment concentration is 1000ppm-50vol%. It also has anti-toxicity properties against impurity gases (NO, CO, O2, H2O) present in the tail gas.

[0020] The beneficial effects of this invention are as follows:

[0021] (1) The preparation method of the present invention is simple and the production process has good repeatability, which fully meets the requirements of industrial mass production.

[0022] (2) The preparation method of the present invention can make certain changes to the precursor (pure metal element Co or MOF containing other metals, the ligands corresponding to MOF contain N and C elements) and calcination conditions as needed, and can effectively control the elemental composition and morphological structure of the catalyst to meet more complex industrial use environments.

[0023] (3) The present invention has good activity at medium and low temperatures. For example, in Example 15, the conversion rate of N2O reaches more than 95% at 350°C on the prepared catalyst, and N2O can be completely eliminated at 400°C.

[0024] (4) The catalyst of the present invention has a wide range of applications and can handle a wide range of N2O concentrations, from 1000ppm to 50vol%. At the same time, it has a certain resistance to poisoning of impurity gases (such as NO, CO, O2, H2O) present in N2O tail gas, and the catalyst has good thermal stability and long life. Attached Figure Description

[0025] Figure 1 X-ray diffraction patterns of different cobalt precursors and the catalyst of Example 3;

[0026] Figure 2 Figures showing the conversion rate of N2O to temperature for catalysts prepared for different cobalt precursors in Examples 1-4.

[0027] Figure 3 The conversion rate of N2O to catalysts prepared under different calcination conditions in Example 5-10 varies with temperature.

[0028] Figure 4 The graph shows the change in N2O conversion rate as a function of temperature for the catalysts prepared by multiple calcination in Examples 11-16.

[0029] Figure 5 The N2 adsorption and desorption curves before and after the catalyst reaction in Example 3 are shown.

[0030] Figure 6 The effect of impurity gases (such as NO, CO, O2, H2O) on the catalytic decomposition of N2O by the catalyst in Example 3. Detailed Implementation

[0031] The present invention will be further illustrated below by way of examples, but these examples in no way limit the scope of the present invention.

[0032] The activity of the catalyst in the catalytic decomposition of N2O was evaluated as follows: the prepared catalyst was placed in a micro fixed-bed quartz reactor, and 30% N2O / He was introduced at a gas flow rate of 100 mL / min and a volume hourly space velocity of 30,000 / h. The reaction temperature range was 300–550 °C. Online quantitative gas analysis was performed using a Nicolet Nexus 470 infrared spectrometer with a 2.4-meter optical path length gas analysis cell to obtain the N2O conversion rate. The catalytic products were nitrogen and oxygen.

[0033] Example 1:

[0034] Take 10 grams of cobalt precursor ZIF-67 and place it in a tube furnace. Purge the tube furnace with 50 ml / min of 10% O2 / N2 and purge at room temperature for 30 minutes. Then, heat the furnace from room temperature to 500°C at a rate of 5°C / min and calcine at a constant temperature for 2 hours. Finally, allow the furnace to cool naturally to room temperature under a 10% O2 / N2 atmosphere. Collect the calcined solid sample, which is the ZIF-67-500-O2 catalyst.

[0035] Example 2:

[0036] Take 10 grams of cobalt precursor ZIF-9 and place it in a tube furnace. Purge the tube furnace with 50 ml / min of 10% O2 / N2 and purge at room temperature for 30 minutes. Then, heat the furnace from room temperature to 500°C at a rate of 5°C / min and calcine at a constant temperature for 2 hours. Finally, allow the furnace to cool naturally to room temperature under a 10% O2 / N2 atmosphere. Collect the calcined solid sample, which is the ZIF-9-500-O2 catalyst.

[0037] Example 3:

[0038] Take 10 grams of cobalt precursor MOF-74 and place it in a tube furnace. Purge the tube furnace with 50 ml / min of 10% O2 / N2 and purge at room temperature for 30 minutes. Then, heat the furnace from room temperature to 500°C at a rate of 5°C / min and calcine at a constant temperature for 2 hours. Finally, allow the furnace to cool naturally to room temperature under a 10% O2 / N2 atmosphere. Collect the calcined solid sample, which is the MOF-74-500-O2 catalyst.

[0039] Example 4:

[0040] Take 10 grams of cobalt precursor MOF-71 and place it in a tube furnace. Purge the tube furnace with 50 ml / min of 10% O2 / N2 and purge at room temperature for 30 minutes. Then, heat the furnace from room temperature to 500°C at a rate of 5°C / min and calcine at a constant temperature for 2 hours. Finally, allow the furnace to cool naturally to room temperature under a 10% O2 / N2 atmosphere. Collect the calcined solid sample, which is the MOF-71-500-O2 catalyst.

[0041] Example 5:

[0042] Take 10 grams of cobalt precursor MOF-74 and place it in a tube furnace. Purge the tube furnace with 50 ml / min of 10% O2 / N2 and purge at room temperature for 30 minutes. Then, heat the furnace from room temperature to 500°C at a rate of 10°C / min and calcine at a constant temperature for 2 hours. Finally, allow the furnace to cool naturally to room temperature under a 10% O2 / N2 atmosphere. Collect the calcined solid sample, which is the MOF-74-500-10-O2 catalyst.

[0043] Example 6:

[0044] Take 10 grams of cobalt precursor MOF-74 and place it in a tube furnace. Purge the tube furnace with 50 ml / min of 10% O2 / N2 and purge at room temperature for 30 minutes. Then, heat the furnace from room temperature to 500°C at a rate of 1°C / min and calcine at a constant temperature for 2 hours. Finally, allow the furnace to cool naturally to room temperature under a 10% O2 / N2 atmosphere. Collect the calcined solid sample, which is the MOF-74-500-1-O2 catalyst.

[0045] Example 7:

[0046] Take 10 grams of cobalt precursor MOF-74 and place it in a tube furnace. Purge the tube furnace with 50 ml / min of pure O2. After purging at room temperature for 30 minutes, heat the furnace from room temperature to 500°C at a rate of 1°C / min. After calcining at a constant temperature for 2 hours, allow it to cool naturally to room temperature under a pure O2 atmosphere. Collect the calcined solid sample, which is the MOF-74-500-pure O2 catalyst.

[0047] Example 8:

[0048] Take 10 grams of cobalt precursor MOF-74 and place it in a tube furnace. Purge the tube furnace with 50 ml / min of 10% O2 / N2 and purge at room temperature for 30 minutes. Then, heat the furnace from room temperature to 300°C at a rate of 5°C / min and calcine at a constant temperature for 2 hours. Finally, allow the furnace to cool naturally to room temperature under a 10% O2 / N2 atmosphere. Collect the calcined solid sample, which is the MOF-74-300-O2 catalyst.

[0049] Example 9:

[0050] Take 10 grams of cobalt precursor MOF-74 and place it in a tube furnace. Purge the tube furnace with 50 ml / min of 10% O2 / N2 and purge at room temperature for 30 minutes. Then, heat the furnace from room temperature to 700°C at a rate of 5°C / min and calcine at a constant temperature for 2 hours. Finally, allow the furnace to cool naturally to room temperature under a 10% O2 / N2 atmosphere. Collect the calcined solid sample, which is the MOF-74-700-O2 catalyst.

[0051] Example 10:

[0052] Take 10 grams of cobalt precursor MOF-74 and place it in a tube furnace. Purge the tube furnace with 50 ml / min of 10% N2O / N2. After purging at room temperature for 30 minutes, heat the furnace from room temperature to 500°C at a rate of 1°C / min. After calcining at this temperature for 2 hours, allow it to cool naturally to room temperature under a 10% N2O / N2 atmosphere. Collect the calcined solid sample, which is the MOF-74-500-N2O catalyst.

[0053] Example 11:

[0054] 10 g of cobalt precursor MOF-74 was placed in a tube furnace. N2 was introduced into the tube furnace at a rate of 50 mL / min. After purging at room temperature for 30 minutes, the temperature was increased from room temperature to 500°C at a rate of 5°C / min. After calcination at this temperature for 2 hours, the temperature was naturally cooled to room temperature under an N2 atmosphere. The gas introduced was changed to 10% O2 / N2. After purging at room temperature for 30 minutes, the temperature was increased from room temperature to 300°C at a rate of 5°C / min. After calcination at this temperature for 2 hours, the temperature was naturally cooled to room temperature under a 10% O2 / N2 atmosphere. The calcined solid sample was collected as the MOF-74-(500-N2)-(300-O2) catalyst.

[0055] Example 12:

[0056] 10 g of cobalt precursor MOF-74 was placed in a tube furnace. N2 was introduced into the tube furnace at a rate of 50 mL / min. After purging at room temperature for 30 minutes, the temperature was increased from room temperature to 600°C at a rate of 5°C / min. After calcination at this temperature for 2 hours, the temperature was naturally cooled to room temperature under an N2 atmosphere. The gas introduced was changed to 10% O2 / N2. After purging at room temperature for 30 minutes, the temperature was increased from room temperature to 300°C at a rate of 5°C / min. After calcination at this temperature for 2 hours, the temperature was naturally cooled to room temperature under a 10% O2 / N2 atmosphere. The calcined solid sample was collected as the MOF-74-(600-N2)-(300-O2) catalyst.

[0057] Example 13:

[0058] 10 g of cobalt precursor MOF-74 was placed in a tube furnace. N2 was introduced into the tube furnace at a rate of 50 mL / min. After purging at room temperature for 30 minutes, the temperature was increased from room temperature to 700°C at a rate of 5°C / min. After calcination at this temperature for 2 hours, the temperature was naturally cooled to room temperature under an N2 atmosphere. The gas introduced was changed to 10% O2 / N2. After purging at room temperature for 30 minutes, the temperature was increased from room temperature to 300°C at a rate of 5°C / min. After calcination at this temperature for 2 hours, the temperature was naturally cooled to room temperature under a 10% O2 / N2 atmosphere. The calcined solid sample was collected as the MOF-74-(700-N2)-(300-O2) catalyst.

[0059] Example 14:

[0060] 10 g of cobalt precursor MOF-74 was placed in a tube furnace. He was introduced into the tube furnace at a rate of 50 mL / min. After purging at room temperature for 30 minutes, the temperature was increased from room temperature to 600°C at a rate of 5°C / min. After calcination at this temperature for 2 hours, the temperature was naturally cooled to room temperature under a He atmosphere. The gas introduced was changed to 10% O2 / He. After purging at room temperature for 30 minutes, the temperature was increased from room temperature to 300°C at a rate of 5°C / min. After calcination at this temperature for 2 hours, the temperature was naturally cooled to room temperature under a 10% O2 / hE atmosphere. The calcined solid sample was collected as the MOF-74-(600-He)-(300-O2) catalyst.

[0061] Example 15:

[0062] Ten grams of cobalt precursor MOF-74 were placed in a tube furnace. The tube furnace was evacuated for 2 hours to achieve a vacuum level of less than -0.06 MPa. The temperature was increased from room temperature to 600°C at a rate of 5°C / min, and calcined at this temperature for 2 hours. Then, the temperature was allowed to cool naturally to room temperature under vacuum. The gas introduced was changed to 10% O2 / N2, and the furnace was purged at room temperature for 30 minutes. The temperature was then increased from room temperature to 300°C at a rate of 5°C / min, and calcined at this temperature for 2 hours. Finally, the temperature was allowed to cool naturally to room temperature under a 10% O2 / N2 atmosphere. The calcined solid sample was collected as the MOF-74-(600-vacuum)-(300-O2) catalyst.

[0063] Example 16:

[0064] 10 g of cobalt precursor MOF-74 was placed in a tube furnace. N2 was introduced into the tube furnace at a rate of 50 mL / min. After purging at room temperature for 30 minutes, the temperature was increased from room temperature to 600°C at a rate of 5°C / min. After calcination at this temperature for 2 hours, the temperature was naturally cooled to room temperature under an N2 atmosphere. The gas introduced was changed to 10% O2 / N2. After purging at room temperature for 30 minutes, the temperature was increased from room temperature to 300°C at a rate of 5°C / min. After calcination at this temperature for 2 hours, the temperature was naturally cooled to room temperature under a 10% O2 / N2 atmosphere. The gas introduced was changed to 10% H2 / N2. After purging at room temperature for 30 minutes, the temperature was increased from room temperature to 300℃ at a rate of 5℃ / min. After calcination at a constant temperature for 1 hour, the solid sample was naturally cooled to room temperature under a 10% H2 / N2 atmosphere and collected. This solid sample is the MOF-74-(600-N2)-(300-O2)-(300-H2) catalyst.

[0065] like Figure 2 As shown, the catalysts prepared in Examples 1-4 have different effects on N2O purification. Among them, the catalyst (MOF-74-500-O2) prepared in Example 3 using MOF-74 as a precursor showed the best N2O conversion rate in Examples 1-4. At 500°C, the catalytic decomposition N2O conversion rate exceeded 95%.

[0066] like Figure 3 As shown, different gas atmospheres and calcination conditions have a significant impact on the catalytic activity of the prepared catalysts. The catalyst prepared in Example 8 exhibits excellent N2O purification effect, with an N2O conversion rate of 83% at 350°C and 99% at 400°C.

[0067] like Figure 4 As shown, by controlling the gas atmosphere and calcination conditions, the catalysts prepared by multiple calcinations all have good catalytic activity. Among them, the catalyst prepared in Example 15 has the best catalytic activity, with an N2O conversion rate of over 95% at 350°C and 100% complete N2O conversion at 400°C.

[0068] The samples in Example 3 before and after the catalyst reaction were characterized and analyzed using a surface area analyzer, such as... Figure 5 The changes in specific surface area, total pore volume, and mesopore volume of the samples before and after the reaction were minor and within the experimental error range. This indicates that the structure of the catalyst in Example 3 remained essentially unchanged before and after the reaction, and that the catalyst exhibits good structural stability.

[0069] The effects of adding different impurity gases (NO, CO, O2, H2O) to the reaction gas on the catalytic decomposition of N2O by the catalyst in Example 3 were investigated. Figure 6 Experimental results show that NO and CO have a certain promoting effect on the decomposition of N2O; while the addition of O2 and H2O weakens the catalytic decomposition activity of N2O, but T 50 (Temperature at 50% conversion rate), T 90 The temperature rise (at which 90% conversion is achieved) does not exceed 25°C, indicating that O2 and H2O have a relatively small inhibitory effect on the catalytic performance of the catalyst in Example 3. The catalyst in Example 3 also exhibits a certain degree of resistance to poisoning by impurity gases.

[0070] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for preparing a catalyst derived from Co-MOFs for the catalytic decomposition of N2O, characterized in that, Includes the following steps: A certain amount of Co-MOF precursor was placed in a tube furnace and heated to a specific temperature at a certain heating rate under a certain gas atmosphere. The product was then calcined at that temperature for a period of time, naturally cooled to room temperature, and the solid product was collected. The obtained product was used directly as a catalyst. The calcination atmosphere is composed of inert and oxidizing gases, wherein the content of oxidizing gas is 5-20%, the heating rate is 1-5℃ / min, the calcination temperature is 300-500℃, and the calcination time is 2-5 hours; the Co-MOF precursor is one of ZIF-67, ZIF-9, MOF-74, and MOF-71. Or may include the following steps: (1) A certain amount of Co-MOF precursor is placed in a tube furnace and heated to a specific temperature at a certain heating rate under a certain gas atmosphere or vacuum conditions. The product is then calcined at that temperature for a period of time, naturally cooled to room temperature, and the solid product is collected. (2) Changing the calcination conditions and continuing to calcinate once or twice is equivalent to a total of two or three calcinations, and finally obtaining N and C doped cobalt oxide catalyst; The Co-MOF precursor is one of ZIF-67, ZIF-9, MOF-74, and MOF-71; When calcining twice in total, the first calcination atmosphere is inert gas or vacuum, the heating rate is 1~5℃ / min, the calcination temperature is 500~800℃, and the calcination time is 2~5 hours. The second calcination atmosphere is composed of inert gas and oxidizing gas, with the oxidizing gas content being 5~20%, the heating rate is 1~5℃ / min, the calcination temperature is 300~500℃, and the calcination time is 2~5 hours. When calcining three times in total, the first calcination atmosphere is inert gas or vacuum, the heating rate is 1~5℃ / min, and the calcination time is... The first calcination is carried out at a temperature of 500-800℃ for 2-5 hours. The second calcination is carried out at an atmosphere composed of inert and oxidizing gases, with the content of oxidizing gases being 5-20%. The heating rate is 1-5℃ / minute, the calcination temperature is 300-500℃, and the calcination time is 2-5 hours. The third calcination is carried out at an atmosphere composed of reducing and inert gases, with the content of reducing gases being 5-20%. The heating rate is 1-5℃ / minute, the calcination temperature is 100-350℃, and the calcination time is 0.5-2 hours.

2. The catalyst prepared according to the preparation method of claim 1.

3. The application of the catalyst prepared according to the preparation method of claim 1, characterized in that, It can be directly used for the medium- and low-temperature direct catalytic decomposition of high-concentration N2O in industrial tail gas emitted by nitric acid plants, adipic acid plants, or caprolactam plants. The reaction temperature range is 300~550℃, and the N2O treatment concentration is 1000 ppm~50 vol%. It also has anti-toxicity properties against impurity gases NO, CO, O2, and H2O present in the tail gas.

Images