Monatomic flexible denitration catalyst with efficient water resistance and sulfur resistance and preparation method of monatomic flexible denitration catalyst

Abstract

The invention provides a monatomic flexible denitration catalyst. The monatomic flexible denitration catalyst comprises a graphene oxide / melamine sponge composite carrier and monatomic active components loaded on the composite carrier, the active component comprises manganese, cobalt, cerium or iron. According to the invention, the melamine sponge with a flexible net structure is used as a carrier, the shape and structure stability can be conveniently maintained in a complex reaction environment due to a unique porous structure and high flexibility, active metal sites can be effectively borne and dispersed, and the contact between the catalyst and reaction gas is enhanced; the monatomic structure has low poisoning sensitivity to sulfur and water molecules, and has excellent sulfur resistance and water resistance; the graphene oxide is used as a modifier, and the ZIF-8 is used as a monatomic framework, so that not only can the combination of the sponge and the active component be promoted, but also the microporous structure of the melamine sponge can be modified, the redox balance in the reaction atmosphere can be maintained, the selectivity and durability of the SCR reaction can be improved, and the damage of high-temperature calcination to the carrier structure can be avoided.

Description

Technical Field

[0001] The present invention belongs to the technical field of the preparation of single-atom flexible denitrification catalysts, and relates to a single-atom flexible denitrification catalyst and a preparation method thereof, in particular to a single-atom flexible denitrification catalyst with high water and sulfur resistance and a preparation method thereof. Background Art

[0002] Nitrogen oxides (NO x ) are one of the main sources of air pollution and pose a serious threat to the environment and human health. Selective Catalytic Reduction (SCR) technology is the most effective means of NO x control. NO generated by human activities x mainly comes from the combustion emissions of stationary sources such as coal-fired power plants and mobile sources such as diesel vehicles. The waste gases generated from these emission sources often have complex compositions, containing SO 2 , H 2 O and other components. However, traditional SCR catalysts face challenges from poisoning substances in practical applications. For example, the accumulation of sulfides and H 2 O will lead to a decrease in the activity of the catalyst, seriously affecting the conversion efficiency of NO x . Therefore, developing catalysts with stronger anti-poisoning ability has become the key to improving the efficiency of SCR technology.

[0003] In the field of heterogeneous catalysis, single-atom catalysts (SACs) have become an important research direction in the catalytic field due to their unique structural advantages. Currently, SACs are mainly defined as single metal atoms "supported" or "embedded" on solid supports through covalent bonds, coordination bonds or ionic bonds. The interaction between single atoms and the surface may have different properties. SACs often have highly dispersed active sites and high atomic utilization efficiency, and can provide excellent catalytic performance at low loadings. The metal atoms in metal nanoparticle catalysts usually exist in the form of clusters or nanoparticles, which means that many active sites are aggregated together. This may cause some active sites to be shielded or unable to participate in the reaction effectively. Single-atom catalysts can avoid the agglomeration phenomenon in traditional catalysts, and thus exhibit stronger anti-poisoning ability at high temperatures and in complex environments.

[0004] Due to the high metal utilization efficiency and superior catalytic performance of SACs, the benefits during long-term use may be even higher. Therefore, in the practical application of single-atom catalysts in the SCR field, the anti-poisoning performance and long-term stability of the catalyst are particularly important. A strong interaction (such as covalent bond or coordination bond) may form between the single atoms and the support. SACs usually have high thermal stability and chemical stability, and can maintain a long lifespan under harsh reaction conditions. However, due to the relatively large exposure of surface metal atoms in metal nanoparticle catalysts, metal nanoparticle catalysts are more sensitive to poisoning substances such as SO x and H 2 O, and are prone to losing activity.

[0005] Moreover, currently in the SCR reaction, sulfur-containing and water-containing environments can cause catalyst poisoning or inactivation. Due to the integrated structure of the monolithic catalyst, the active sites are not easily regenerated. When poisoned, it needs to be replaced or regenerated more frequently, resulting in increased maintenance costs and it is not easy to replace.

[0006] Therefore, how to design a more suitable catalyst with anti-poisoning ability to solve the above problems existing in the existing denitration catalysts has broad application prospects and is also one of the focuses widely concerned by many researchers in the industry. Summary of the Invention

[0007] In view of this, the technical problem to be solved by the present invention is to provide a single-atom flexible denitration catalyst and its preparation method, especially a single-atom flexible denitration catalyst with high water and sulfur resistance and its preparation method. The present invention loads the single-atom catalyst on the GO-modified melamine sponge, and uses the high specific surface area and three-dimensional sponge structure of graphene oxide to increase the exposure of active sites and improve the contact probability between NO x and the active sites, enhancing the catalytic activity of the SCR reaction. The hydrophilicity and anti-poisoning characteristics of GO modification and melamine sponge can reduce the strong adsorption of SO 2 and water vapor on the single atoms, thereby enhancing the sulfur and water resistance of the catalyst and extending its service life. Moreover, the preparation method is simple, the conditions are mild, and the controllability is strong, which is more suitable for the popularization and application of industrial production.

[0008] The present invention provides a single-atom flexible denitration catalyst, which includes a graphene oxide / melamine sponge composite support and a single-atom active component loaded on the composite support;

[0009] The active component includes manganese, cobalt, cerium or iron.

[0010] Preferably, the graphene oxide / melamine sponge composite support is specifically graphene oxide attached to the melamine sponge;

[0011] The specific single-atom active component is an active component complex in which the active component single atoms are supported on a nitrogen-doped carbon framework;

[0012] In the denitration catalyst, the content of the active component is 0.2 wt% to 5 wt%.

[0013] Preferably, in the graphene oxide / melamine sponge composite support, the loading amount of graphene oxide is 10 wt% to 50 wt%;

[0014] The mass of the active component complex is 20 wt% to 50 wt% of the mass of the graphene oxide / melamine sponge composite support;

[0015] The porosity of the melamine sponge is 90% to 99%;

[0016] The specific single-atom flexible denitration catalyst is a water- and sulfur-resistant single-atom flexible denitration catalyst.

[0017] Preferably, the nitrogen-doped carbon framework is obtained by calcining a metal-organic framework material;

[0018] The metal-organic framework material includes ZIF-8;

[0019] The temperature of the calcination is 600 to 1000 °C;

[0020] The time of the calcination is 1 to 4 h;

[0021] The single-atom flexible denitration catalyst is a catalyst for the NH 3 -SCR denitration system.

[0022] The present invention also provides a preparation method of a single-atom flexible denitration catalyst, comprising the following steps:

[0023] 1) Under a protective atmosphere, the metal-organic framework material loaded with the active component metal source is calcined to obtain an active component complex;

[0024] The melamine sponge is immersed in a graphene oxide suspension and dried to obtain a modified melamine sponge attached with graphene oxide;

[0025] 2) The modified melamine sponge is immersed in a solution of the active component complex, and heated and reacted to obtain a single-atom flexible denitration catalyst.

[0026] Preferably, the preparation method of the metal-organic framework material loaded with the active component metal source comprises the following steps:

[0027] a) The active component metal source and zinc nitrate hexahydrate are dissolved in a first solvent to obtain a solution A;

[0028] Dissolve the organic precursor of the metal-organic framework material in a second solvent to obtain solution B;

[0029] b) Mix solution A and solution B obtained in the above steps and react to obtain a metal-organic framework material loaded with an active component metal source.

[0030] Preferably, the metal source includes a soluble organometallic source and / or a soluble inorganic metal salt;

[0031] The organic precursor of the metal-organic framework material includes 2-methylimidazole;

[0032] The molar ratio of the active component metal source to zinc nitrate hexahydrate, based on the metal element, is 1:(1-5);

[0033] The molar ratio of the active component metal source, based on the metal element, to the organic precursor of the metal-organic framework material is 1:(5-20).

[0034] Preferably, the metal source includes a metal acetylacetonate compound and / or a metal nitrate;

[0035] The first solvent and the second solvent are each independently selected from methanol and / or ethanol;

[0036] In step b), the reaction temperature is 15-120 °C;

[0037] In step b), the reaction time is 3-12 h.

[0038] Preferably, the calcination temperature is 600-1000 °C;

[0039] The calcination time is 1-4 h;

[0040] In step 1), the immersion time is 30-120 min;

[0041] In the modified melamine sponge, graphene oxide is uniformly distributed in the melamine sponge.

[0042] Preferably, the solvent of the solution of the active component complex includes methanol and / or ethanol;

[0043] In step 2), after immersion, it further includes the step of repeatedly squeezing the modified melamine sponge;

[0044] The temperature of the heating reaction is 50-90 °C;

[0045] The time of the heating reaction is 2-12 h.

[0046] The present invention provides a single-atom flexible denitration catalyst, which comprises a graphene oxide / melamine sponge composite support and single-atom active components supported on the composite support; the active components include manganese, cobalt, cerium or iron. Compared with the prior art, the present invention believes that monolithic flexible catalysts usually adopt honeycomb, reticular or porous structures, enabling them to remain stable under high temperature, gas flow impact and vibration conditions, being not easily pulverized or broken, and prolonging the service life. Compared with rigid supports, flexible catalysts have good toughness and deformability, can adapt to the deformation of equipment and fluid impact during installation and use, and are suitable for complex industrial operation environments. Melamine sponge has a three-dimensional network structure with low density and high porosity, providing rich transmission channels for reaction gases. This structure increases the specific surface area, helps to evenly disperse the active sites, and improves the denitration efficiency of the catalyst. The sponge surface is easy to be chemically modified through simple methods, enabling it to carry active species such as single atoms or nanoparticles. Uniform loading can be achieved through simple impregnation or coating methods, thereby enhancing the denitration activity of the SCR catalyst. The surface-modified melamine sponge can have good water and sulfur resistance characteristics, helping to maintain the high efficiency of the catalyst in a humid and sulfur-containing atmosphere, and reducing the interference of gases such as SO 2 , H 2 O, etc. Moreover, the present invention finds that the oxygen-containing functional groups (such as carboxyl groups, hydroxyl groups, etc.) of graphene oxide (GO) can provide rich anchoring sites for single atoms, further disperse the single atoms, prevent their aggregation, ensure the exposure of high-active sites, and improve the catalytic performance and atomic utilization rate. The GO sheets have good electrical conductivity, forming a synergistic effect with the porous network of the melamine sponge, significantly enhancing the electron transfer rate. This characteristic plays a positive role in optimizing the reaction path of the single-atom catalyst in the SCR denitration reaction, promoting the efficient reduction of NO x , and increasing the reaction rate and denitration efficiency.

[0047] Based on this, the present invention creatively designs a single-atom flexible denitration catalyst with a specific composition and structure. The single-atom metal active component is loaded onto graphene-modified melamine sponge, which is an improved single-atom flexible denitration catalyst of melamine sponge with high efficiency in water and sulfur resistance. The present invention uses melamine sponge with a flexible network structure as the carrier, which has a unique porous structure and high flexibility, facilitating the maintenance of shape and structural stability in a complex reaction environment. At the same time, the sponge can effectively carry and disperse the active metal sites, enhancing the contact between the catalyst and the reaction gas. The single-atom structure has low sensitivity to the poisoning of sulfur and water molecules and has excellent sulfur and water resistance. In addition, by selecting appropriate additives, not only can the combination of the sponge and the active component be promoted, but the microporous structure of the modified melamine sponge helps to maintain the redox balance in the reaction atmosphere, improving the selectivity and durability of the SCR reaction. The present invention uses graphene oxide as an additive and ZIF-8 as a single-atom framework, and prepares the flexible denitration catalyst of melamine sponge by the impregnation method. It avoids the damage to the carrier structure caused by high-temperature calcination and has excellent water and sulfur resistance performance.

[0048] The flexible denitration catalyst with high efficiency in water and sulfur resistance provided by the present invention loads the single-atom catalyst on the GO-modified melamine sponge, and uses the high specific surface area and three-dimensional sponge structure of graphene oxide to increase the exposure of active sites and improve the contact probability between NO x and the active sites, enhancing the catalytic activity of the SCR reaction. The hydrophilicity and anti-poisoning characteristics of GO modification and melamine sponge can reduce the strong adsorption of SO 2 and water vapor on the single atom, thereby enhancing the sulfur and water resistance performance of the catalyst and prolonging the service life.

[0049] The present invention also provides a preparation method of a flexible denitration catalyst. In this preparation method, during the preparation process, the active component is calcined separately without high-temperature treatment of the flexible carrier. The present invention prepares a single-atom flexible denitration catalyst with high efficiency in water and sulfur resistance by a step-by-step method. First, high-temperature calcination is used to support the single-atom active component with ZIF-8 as the organic framework, and the impregnation synthesis method is used to prepare a flexible denitration catalyst containing a single-atom active component loaded on graphene-modified melamine sponge. This catalyst ensures the flexible characteristics of melamine sponge and has a high atomic utilization rate.

[0050] The flexible denitration catalyst prepared by the present invention avoids problems such as the shedding of active centers, has characteristics such as high efficiency in water and sulfur resistance, shows high-efficiency selective catalytic reduction (SCR) denitration activity and excellent water and sulfur resistance performance, has a high selectivity for the target product nitrogen, and can be applied in the NH 3 -SCR denitration reaction, having good application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 SCR denitration activity diagram of the Mn-SA@MSGO catalyst sample prepared in Example 3 of the present invention;

[0052] Figure 2 N 2 selectivity diagram of the Mn-SA@MSGO catalyst sample prepared in Example 3 of the present invention;

[0053] Figure 3 SO 2 Catalyst activity diagram of the SO resistance test of the Mn-SA@MSGO catalyst sample prepared in Example 3 of the present invention;

[0054] Figure 4 H 2 Catalyst activity diagram of the H₂O resistance test of the Mn-SA@MSGO catalyst sample prepared in Example 3 of the present invention;

[0055] Figure 5 Catalyst activity diagram of the stability test of the Mn-SA@MSGO catalyst sample prepared in Example 3 of the present invention;

[0056] Figure 6 Fourier transform infrared spectrometer test diagram of the Mn-SA@MSGO catalyst sample prepared in Example 3 of the present invention, as well as Mn-ZIF8 and Mn-SA;

[0057] Figure 7 Raman spectrometer test diagram of the Mn-SA@MSGO catalyst sample prepared in Example 3 of the present invention, as well as Mn-SA;

[0058] Figure 8 Microscopic morphology diagram of the Mn-SA@MSGO catalyst sample prepared in Example 3 of the present invention. Detailed implementation manners

[0059] In order to further understand the present invention, the preferred implementation manners of the present invention will be described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention rather than limiting the claims of the present invention.

[0060] There are no particular restrictions on the sources of all raw materials of the present invention, and they can be purchased on the market or prepared by conventional methods well-known to those skilled in the art.

[0061] There are no particular restrictions on the purity of all raw materials of the present invention. The present invention preferably uses analytical pure or the purity conventional in the field of SCR denitration catalyst preparation.

[0062] The term "loading amount" in the present invention refers to the mass ratio of the active metal element to the catalyst.

[0063] In the present invention, melamine sponge is abbreviated as MS, and graphene oxide is abbreviated as GO.

[0064] The room temperature in the present invention generally refers to 15 - 30 °C.

[0065] The melamine sponge in the present invention is also called a melamine sponge, which is a material prepared by using melamine resin for invoice preparation and has a three-dimensional network structure.

[0066] In the melamine sponge of the present invention, the porosity of the sponge carrier is 90% - 99%, and the density is 8 - 11 mg / cm 3 。

[0067] The present invention provides a single-atom flexible denitration catalyst, which includes a graphene oxide / melamine sponge composite carrier and a single-atom active component supported on the composite carrier;

[0068] The active component includes manganese, cobalt, cerium or iron.

[0069] In the present invention, the graphene oxide / melamine sponge composite carrier is specifically preferably graphene oxide attached to the melamine sponge.

[0070] In the present invention, the single-atom active component is specifically preferably an active component composite in which the active component single atoms are supported on a nitrogen-doped carbon framework.

[0071] In the denitration catalyst of the present invention, the content of the active component is preferably 0.2 wt% - 5 wt%, more preferably 0.5 wt% - 4 wt%, and even more preferably 1 wt% - 3 wt%.

[0072] In the graphene oxide / melamine sponge composite carrier of the present invention, the loading amount of graphene oxide is preferably 10 wt% - 50 wt%, more preferably 15 wt% - 45 wt%, even more preferably 20 wt% - 40 wt%, and even more preferably 25 wt% - 35 wt%.

[0073] In the present invention, the mass of the active component composite is preferably 20% - 50 wt% of the mass of the graphene oxide / melamine sponge composite carrier, more preferably 25% - 45 wt%, and even more preferably 30% - 40 wt%.

[0074] In the present invention, the porosity of the melamine sponge is preferably 90% - 99%, more preferably 92% - 97%, and even more preferably 94% - 95%.

[0075] In the present invention, the single-atom flexible denitration catalyst is specifically preferably a water- and sulfur-resistant single-atom flexible denitration catalyst.

[0076] In the present invention, the nitrogen-doped carbon framework is preferably obtained by calcining a metal-organic framework material.

[0077] In the present invention, the metal-organic framework material preferably includes ZIF-8.

[0078] In the present invention, the calcination temperature is preferably 600-1000 °C, more preferably 700-980 °C, still more preferably 800-960 °C, and even more preferably 900-950 °C.

[0079] In the present invention, the calcination time is preferably 1-4 h, more preferably 1.5-3.5 h, and still more preferably 2-3 h.

[0080] In the present invention, the single-atom flexible denitration catalyst is specifically a catalyst for the NH 3 -SCR denitration system.

[0081] The present invention provides a method for preparing a single-atom flexible denitration catalyst, comprising the following steps:

[0082] 1) Under a protective atmosphere, the metal-organic framework material loaded with the active component metal source is calcined to obtain an active component composite;

[0083] The melamine sponge is immersed in the graphene oxide suspension, and after drying, a modified melamine sponge attached with graphene oxide is obtained;

[0084] 2) The modified melamine sponge is immersed in the solution of the active component composite, and heated and reacted to obtain a single-atom flexible denitration catalyst.

[0085] The present invention first calcines the metal-organic framework material loaded with the active component metal source under a protective atmosphere to obtain an active component composite;

[0086] The melamine sponge is immersed in the graphene oxide suspension, and after drying, a modified melamine sponge attached with graphene oxide is obtained.

[0087] In the present invention, the preparation method of the metal-organic framework material loaded with the active component metal source preferably includes the following steps:

[0088] a) The active component metal source and zinc nitrate hexahydrate are dissolved in a first solvent to obtain solution A;

[0089] The organic precursor of the metal-organic framework material is dissolved in a second solvent to obtain solution B;

[0090] b) The solution A and solution B obtained in the above steps are mixed and reacted to obtain a metal-organic framework material loaded with the active component metal source.

[0091] First, in the present invention, an active component metal source and zinc nitrate hexahydrate are dissolved in a first solvent to obtain solution A;

[0092] An organic precursor of a metal-organic framework material is dissolved in a second solvent to obtain solution B.

[0093] In the present invention, the metal source preferably includes a soluble organometallic source and / or a soluble inorganic metal salt.

[0094] In the present invention, the organic precursor of the metal-organic framework material preferably includes 2-methylimidazole.

[0095] In the present invention, the molar ratio of the active component metal source to zinc nitrate hexahydrate, based on the metal element, is preferably 1:(1 - 5), more preferably 1:(1.5 - 4.5), more preferably 1:(2 - 4), and even more preferably 1:(2.5 - 3.5).

[0096] In the present invention, the molar ratio of the active component metal source, based on the metal element, to the organic precursor of the metal-organic framework material is preferably 1:(5 - 20), more preferably 1:(8 - 17), and even more preferably 1:(11 - 14).

[0097] In the present invention, the metal source preferably includes a metal acetylacetonate compound and / or a metal nitrate, and more preferably a metal acetylacetonate compound or a metal nitrate.

[0098] In the present invention, the first solvent and the second solvent are each independently preferably selected from methanol and / or ethanol, and more preferably methanol or ethanol.

[0099] In the present invention, the solution A and solution B obtained in the above steps are then mixed and reacted to obtain a metal-organic framework material loaded with the active component metal source.

[0100] In the present invention, in step b), the reaction temperature is preferably 15 - 120°C, more preferably 65 - 120°C, even more preferably 115 - 120°C, and specifically can be 120°C.

[0101] In the present invention, in step b), the reaction time is preferably 3 - 12 h, more preferably 5 - 10 h, even more preferably 6 - 8 h, and specifically can be 6 h.

[0102] In the present invention, the calcination temperature is preferably 600 - 1000°C, more preferably 700 - 980°C, even more preferably 800 - 960°C, and even more preferably 900 - 950°C.

[0103] In the present invention, the calcination time is 1 to 4 h, more preferably 1.5 to 3.5 h, still more preferably 2 to 3 h, and specifically may be 3 h.

[0104] In the present invention, in step 1), the immersion time is preferably 30 to 120 min, more preferably 50 to 100 min, still more preferably 70 to 80 min.

[0105] Finally, the modified melamine sponge is immersed in a solution of the active component complex, and heated and reacted to obtain a single-atom flexible denitration catalyst.

[0106] In the present invention, in the modified melamine sponge, graphene oxide is uniformly distributed in the melamine sponge.

[0107] In the present invention, the solvent of the solution of the active component complex preferably includes methanol and / or ethanol, more preferably methanol or ethanol.

[0108] The present invention provides a preparation method of a highly efficient water-resistant and sulfur-resistant flexible single-atom SCR denitration catalyst. First, using ZIF-8 as the organic framework of the single-atom active component, the stable dispersion of single atoms is achieved through high-temperature calcination. On this basis, the single-atom active component is loaded onto the graphene-modified melamine sponge by the impregnation method, thereby preparing an SCR catalyst with flexible characteristics. This catalyst not only maintains the flexibility of the melamine sponge, ensuring its mechanical stability in industrial applications, but also significantly improves the atomic utilization rate of the catalyst due to the introduction of graphene and the reasonable distribution of single-atom sites. The finally prepared catalyst exhibits excellent SCR denitration activity, high nitrogen selectivity, as well as good water resistance and sulfur resistance. These characteristics enable this flexible catalyst to show a long service life in a complex industrial environment and have broad industrial application prospects.

[0109] To complete and refine the overall technical solution of the present invention, better ensure the composition and structure of the single-atom flexible denitration catalyst, and further improve the water and sulfur resistance, service life, and denitration efficiency of the single-atom flexible denitration catalyst, the above-mentioned single-atom flexible denitration catalyst with high water and sulfur resistance and its preparation method may specifically include the following content:

[0110] A flexible denitration catalyst, comprising: an active component, a melamine sponge, and graphene oxide, wherein the active component includes one of manganese, cobalt, cerium, and iron.

[0111] Specifically, the content of the active component is 0.2 wt% to 5 wt%.

[0112] Specifically, a suitable organic framework is selected to support the single-atom active sites;

[0113] Specifically, the organic framework is ZIF-8.

[0114] Specifically, the loading amount of graphene oxide relative to the melamine sponge is 10 wt% - 50 wt%.

[0115] The present invention provides a preparation method of the flexible denitration catalyst described in the above technical solution, including: dissolving one of the metal sources (M) and zinc nitrate hexahydrate in solution A, dissolving 2-methylimidazole in solution B, and stirring.

[0116] Mix solution A and solution B evenly, and heat for reaction. Centrifuge, wash, and dry to obtain M@ZIF-8.

[0117] Heat and calcine M@ZIF-8 in an inert gas atmosphere, and then cool to room temperature to obtain M-SA.

[0118] Immerse the melamine sponge (MS) in the graphene oxide suspension, take out the melamine sponge attached with graphene oxide (GO), and dry it to obtain MSGO; immerse MSGO in the solution containing M-SA, react under heating conditions, and then perform a drying treatment to obtain the flexible denitration catalyst.

[0119] Specifically, the temperature of the drying treatment is from room temperature to 90 °C.

[0120] Specifically, dissolve one of the metal sources (M) and zinc nitrate hexahydrate in solution A, and dissolve 2-methylimidazole in solution B.

[0121] Specifically, the solution is one of methanol or ethanol.

[0122] Specifically, the metal source (M) is selected as a soluble metal source; the metal source includes an organometallic source, an inorganic metal salt, and the elements include one of manganese, cobalt, cerium, and iron.

[0123] Specifically, the active component is an organometallic manganese source, and the molar ratio of the manganese source to zinc nitrate hexahydrate is 1:1 - 1:5.

[0124] Specifically, the molar ratio of the manganese source to 2-methylimidazole is 1:5 - 1:20.

[0125] Specifically, it also includes one of the elements cobalt, cerium, and iron.

[0126] Specifically, heat and calcine M@ZIF-8 in an inert gas atmosphere.

[0127] Specifically, the inert atmosphere is one of nitrogen or argon.

[0128] Specifically, the calcination temperature is 900 - 1000 °C, and the calcination time is 3 h.

[0129] Specifically, the mass ratio of melamine sponge to graphene oxide is 1:0.1 to 1:0.5.

[0130] Specifically, the melamine sponge is immersed in the graphene oxide suspension for 30 to 120 minutes.

[0131] Specifically, MSGO is immersed in a solution containing M-SA and reacted under heating conditions.

[0132] Specifically, the amount of the M-SA is 20%-50% of the mass of MSGO.

[0133] Specifically, MSGO containing M-SA is reacted under heating conditions and then dried.

[0134] Specifically, MSGO containing M-SA is reacted at 50-90° C. for 2-12 h.

[0135] Specifically, the drying is performed at room temperature to 90°C.

[0136] The present invention provides a flexible denitration catalyst as described in any one of the above technical solutions in NH 3 -Application in SCR denitrification system;

[0137] Specifically, in the reaction system, under the action of the above catalyst, nitrogen oxides and ammonia undergo redox reaction, and the reaction temperature is 150-300°C.

[0138] The flexible denitration catalyst provided by the present invention comprises: an active component, a melamine sponge and graphene oxide, wherein the active component comprises one of manganese, cobalt, cerium and iron. In the catalyst, the modified melamine sponge has good flexibility and high temperature stability, and can maintain the structural integrity of the catalyst under high temperature and severe flow rate fluctuations. GO has excellent electronic conductivity, which helps to promote the electron transfer process in the SCR reaction. Loading the single-atom catalyst on the conductive GO modified carrier can accelerate the catalytic reaction rate, improve the electron transfer process, and further improve the reaction efficiency and N 2 Selectivity. Can effectively inhibit SO 2 and H 2 The strong adsorption of O reduces the occupation of active sites by these molecules and maintains the activity of the catalyst. It not only reduces the loading amount of metal active components, but also effectively improves the reaction rate.

[0139] The preparation method of the flexible denitration catalyst provided by the present invention includes: dissolving one of the metal sources (M) and zinc nitrate hexahydrate in solution A, dissolving 2-methylimidazole in solution B, and stirring. Mix solution A and solution B evenly and heat for reaction. A precipitate is formed by the reaction, and after centrifugation, washing and drying, M@ZIF-8 is obtained; M@ZIF-8 is heated and calcined in an inert gas atmosphere and then cooled to room temperature to obtain M-SA; the melamine sponge (MS) is immersed in the graphene oxide suspension, and the melamine sponge attached with graphene oxide (GO) is taken out and dried to obtain MSGO; MSGO is immersed in the solution containing M-SA and reacted under heating conditions, and then dried to obtain the flexible denitration catalyst. The flexible denitration catalyst is a single-atom metal active component loaded onto the graphene-modified melamine sponge. The flexible denitration catalyst prepared by the present invention avoids problems such as the shedding of active centers and has characteristics such as high-efficiency water and sulfur resistance.

[0140] Furthermore,

[0141] The flexible denitration catalyst of the present invention includes: an active component, a melamine sponge, and graphene oxide, and the active component includes one of manganese, cobalt, cerium, and iron.

[0142] In some embodiments, the active component in the catalyst is manganese.

[0143] The organic framework supporting the manganese single-atom active component is ZIF-8.

[0144] Preferably, the content of the active component manganese is 0.5 wt% - 3 wt%.

[0145] Graphene oxide can be prepared by all methods disclosed in the prior art.

[0146] As a preferred scheme, the method for preparing graphene oxide includes: 1) adding concentrated sulfuric acid to graphite powder and sodium nitrate to obtain a first mixture; 2) adding potassium permanganate to the first mixture at low temperature, and heating and reacting to obtain a second mixture; 3) adding water to the second mixture at low temperature, and then heating and reacting to obtain a third mixture; 4) adding hydrogen peroxide to the third mixture, cooling to room temperature, and then washing and drying to obtain graphene oxide.

[0147] In step 2), the low temperature refers to 0 - 5 °C.

[0148] Preferably, in step 2), the first mixture and potassium permanganate are maintained below 20 °C during the reaction.

[0149] In step 3), the reaction temperature is about 95 °C.

[0150] In step 3), hydrogen peroxide is added to the third mixture when it is cooled to about 60 °C.

[0151] More preferably, the method for preparing graphene oxide includes:

[0152] Concentrated sulfuric acid is added to graphite powder and sodium nitrate to obtain a first mixture, and the first mixture is stirred in an ice bath at 0 - 5°C; potassium permanganate is added to the first mixture under the condition of an ice bath at 0 - 5°C, and the temperature of the mixture is always maintained below 20°C, and the reaction is stirred for 3 h to obtain a second mixture; deionized water is added to the second mixture under the condition of an ice bath at 0 - 5°C, and the temperature of the mixture is always maintained below 50°C. After adding all the deionized water, it is transferred to a water bath at 95°C and stirred for 1 h to obtain a third mixture; when the temperature of the third mixture drops to 60°C, hydrogen peroxide is added, and it is cooled to room temperature; then it is washed with deionized water until neutral and dried to obtain graphene oxide (GO).

[0153] In some embodiments, the melamine sponge (MS) is immersed in the graphene oxide (GO) suspension. The mass ratio of the melamine sponge to the graphene oxide is 1:0.1 - 1:0.5. The graphene oxide can be uniformly distributed in the melamine sponge.

[0154] The time for the melamine sponge to be immersed in the graphene oxide suspension is not limited, as long as the loading amount of the graphene oxide can be satisfied.

[0155] Preferably, the time for the melamine sponge to be immersed in the graphene oxide suspension is 30 - 120 minutes.

[0156] The temperature for the drying treatment is room temperature - 90°C.

[0157] In some embodiments, the loading amount of the graphene oxide relative to the melamine sponge is 10 wt% - 50 wt%.

[0158] A reasonable amount of GO can effectively increase the specific surface area of the melamine sponge, provide more contact areas for SCR reactants, and increase the adsorption probability of NO x molecules. However, too much GO may block the pores of the sponge, affect the gas mass transfer process, and limit the diffusion and reaction efficiency of NO x .

[0159] The denitration catalyst provided by the present invention has good electronic conductivity. An appropriate amount of GO can significantly improve the electronic transfer ability of the overall catalyst, accelerate the charge transfer in the SCR reaction process, and improve the reaction rate and N 2 selectivity.

[0160] The preparation method of the flexible denitration catalyst provided by the present invention includes: dissolving one of the metal sources (M) and zinc nitrate hexahydrate in solution A, dissolving 2-methylimidazole in solution B, and stirring. Mix solution A and solution B evenly and heat for reaction. A precipitate is formed by the reaction, and after centrifugation, washing and drying, M@ZIF-8 is obtained; M@ZIF-8 is heated and calcined in an inert gas atmosphere, and then cooled to room temperature to obtain M-SA; the melamine sponge (MS) is immersed in the graphene oxide suspension, and the melamine sponge attached with graphene oxide (GO) is taken out and dried to obtain MSGO; MSGO is immersed in the solution containing M-SA and reacted under heating conditions, and then dried to obtain the flexible denitration catalyst;

[0161] In some embodiments, the preferred solution is one of anhydrous methanol or anhydrous ethanol.

[0162] The metal source can be a soluble organic metal source or an inorganic metal salt, such as manganese acetylacetonate, cobalt nitrate, etc.

[0163] Preferably, the active component is an organic metal manganese source, and the molar ratio of the manganese source to nitric acid hexahydrate is 1:1 to 1:5.

[0164] More preferably, the molar ratio of the manganese source to 2-methylimidazole is 1:5 to 1:20.

[0165] Preferably, it also contains one of cobalt, cerium, and iron elements.

[0166] During the preparation process, M@ZIF-8 is separately calcined at high temperature to obtain M-SA, and M-SA is loaded on MSGO, avoiding the damage to the flexible carrier caused by high temperature. The microstructure of the melamine sponge carrier is a porous and loose network morphology structure, and the macroscopic structure is an integral block, with good flexibility and resilience.

[0167] In some embodiments, M@ZIF-8 is placed in a tube furnace and heated and calcined in an inert gas atmosphere

[0168] Preferably, the inert atmosphere is one of nitrogen or argon, the calcination temperature is 900 - 1000 °C, and the calcination time is 3 h.

[0169] At an appropriate calcination temperature, the ZIF-8 matrix decomposes to form active sites containing Mn single atoms. Low-temperature calcination may lead to incomplete decomposition of the ZIF-8 structure, making it difficult for Mn species to be fully dispersed and restricting the formation of active sites; while too high a calcination temperature may cause Mn atoms to agglomerate to form oxides or metal clusters, weakening the single-atom dispersion and affecting the catalyst activity. ZIF-8 contains a rich nitrogen source, and different forms of nitrogen species (such as pyridine nitrogen and graphitic nitrogen) can be introduced into the carbon-based material by controlling the calcination temperature. These nitrogen species can provide a stable coordination environment for Mn single atoms, enhancing the water and sulfur resistance of the catalyst. High-temperature calcination may cause the removal of nitrogen elements, thus reducing the role of nitrogen coordination and weakening the stability of single atoms.

[0170] In some embodiments, the amount of M-SA is 20% - 50 wt% of the mass of the MSGO sample.

[0171] In some embodiments, MSGO is immersed in a solution containing M-SA and reacted at 50 - 90 °C for 2 - 12 h; drying is carried out at room temperature to 90 °C.

[0172] The flexible denitration catalyst provided by the present invention is applied to the NH 3 -SCR denitration system and has good catalytic performance. In the reaction system, under the action of the above catalyst, nitrogen oxides and ammonia undergo an oxidation-reduction reaction, and the reaction temperature is 150 - 300 °C. Even in a complex environment (such as containing water and sulfur), the catalyst can maintain good catalytic effects in the denitration reaction and has good water and sulfur resistance.

[0173] The above content of the present invention provides a single-atom flexible denitration catalyst with high water and sulfur resistance and its preparation method. The single-atom flexible denitration catalyst designed by the present invention, with a specific composition and structure, has a single-atom metal active component loaded onto graphene-modified melamine sponge, which is a modified single-atom flexible denitration catalyst of melamine sponge with high water and sulfur resistance. The present invention uses melamine sponge with a flexible network structure as the carrier, which has a unique porous structure and high flexibility, facilitating the maintenance of shape and structural stability in a complex reaction environment. At the same time, the sponge can effectively carry and disperse active metal sites, enhancing the contact between the catalyst and reaction gases. The single-atom structure has low poisoning sensitivity to sulfur and water molecules and has excellent sulfur and water resistance. In addition, by selecting appropriate additives, not only can the combination of the sponge and the active component be promoted, but the microporous structure of the modified melamine sponge helps to maintain the oxidation-reduction balance in the reaction atmosphere, improving the selectivity and durability of the SCR reaction. The present invention uses graphene oxide as an additive and ZIF-8 as a single-atom framework, and prepares a flexible denitration catalyst for melamine sponge by an impregnation method. It avoids the damage to the carrier structure caused by high-temperature calcination and has excellent water and sulfur resistance.

[0174] The flexible denitration catalyst with high-efficiency water resistance and sulfur resistance provided by the present invention loads a single-atom catalyst on GO-modified melamine sponge, and utilizes the high specific surface area and three-dimensional sponge structure of graphene oxide to increase the exposure of active sites and improve the contact probability between NO x and the active sites, enhancing the catalytic activity of the SCR reaction. The hydrophilicity and anti-poisoning characteristics of GO modification and melamine sponge can reduce the strong adsorption of SO 2 and water vapor on the single atoms, thereby enhancing the sulfur and water resistance of the catalyst and prolonging the service life.

[0175] The present invention also provides a preparation method of a flexible denitration catalyst. In this preparation method, during the preparation process, the active component is calcined separately without high-temperature treatment of the flexible carrier. The present invention prepares a single-atom flexible denitration catalyst with high-efficiency water resistance and sulfur resistance by a step-by-step method. First, high-temperature calcination is used to support the single-atom active component with ZIF-8 as the organic framework, and an impregnation synthesis method is used to prepare a flexible denitration catalyst containing a single-atom active component loaded on graphene-modified melamine sponge. This catalyst ensures the flexible characteristics of the melamine sponge and has a high atomic utilization rate.

[0176] The flexible denitration catalyst prepared by the present invention avoids problems such as the shedding of active centers, has characteristics such as high-efficiency water resistance and sulfur resistance, shows high-efficiency selective catalytic reduction (SCR) denitration activity and excellent water and sulfur resistance, has a high selectivity for the target product nitrogen, and can be used in the NH 3 -SCR denitration reaction, having good application prospects.

[0177] In order to further illustrate the present invention, the following describes in detail a single-atom flexible denitration catalyst and its preparation method provided by the present invention in combination with examples. However, it should be understood that these examples are implemented on the premise of the technical solution of the present invention, and the detailed implementation methods and specific operation processes are given only to further illustrate the features and advantages of the present invention, rather than a limitation on the claims of the present invention. The protection scope of the present invention is not limited to the following examples.

[0178] Example 1

[0179] Step 1: Weigh manganese acetylacetonate (1.27 g) and zinc nitrate hexahydrate (2.38 g) and dissolve them in methanol (50 ml), and stir for 10 min; dissolve 2-methylimidazole in methanol (75 ml) and stir for 10 min; mix the two evenly and pour them into a stainless steel autoclave with a Teflon liner. The reaction temperature is 120 °C and the reaction time is 6 h. Cool to room temperature, wash with methanol by centrifugation to obtain a precipitate, and dry to obtain Mn@ZIF-8.

[0180] Step 2: Place the prepared Mn@ZIF-8 in a porcelain boat and put it into a tubular furnace. Under N 2 atmosphere, calcine at 950 °C for 1 h, cool to room temperature, and obtain Mn-SA(1h).

[0181] Step 3: Weigh graphite powder (5 g) and sodium nitrate (3 g) and place them in a 1 L beaker; measure concentrated sulfuric acid (120 mL) and add it to the beaker, stir for half an hour under ice bath conditions; weigh potassium permanganate (20 g) and slowly add it under low temperature conditions, stir at 35 °C for 3 h. Slowly add deionized water (600 mL), and use ice bath when adding water. After adding all the deionized water, transfer it to a water bath at 95 °C and stir for 1 h. When the temperature drops to 60 °C, add 30% hydrogen peroxide (15 mL), and gradually wait until it cools to room temperature. Then centrifuge and wash with deionized water until neutral, and freeze-dry;

[0182] Step 4: Weigh 0.05 g of freeze-dried graphene oxide and ultrasonically disperse it in 8 ml of deionized water to form a uniform graphene oxide suspension. Then, completely immerse 0.1 g of melamine sponge in the graphene oxide suspension for 30 minutes, take it out and dry it at 50 °C to obtain MSGO;

[0183] Step 5: According to a loading amount of 60% of the foam sample mass, ultrasonically disperse Mn-SA(1h) in 8 ml of methanol solution;

[0184] Step 6: Immerse the MSGO prepared in Step 4 into the solution in Step 5, squeeze repeatedly, impregnate for 4 h, and then dry to obtain a flexible denitration catalyst Mn-SA(1h)@MSGO modified with manganese single-atom loaded graphene oxide on melamine sponge.

[0185] Example 2

[0186] The method and parameters for preparing the denitration catalyst in Example 2 refer to Example 1, the difference being the calcination time in Step 2. The calcination time in Step 2 of this example is 2 h. The obtained catalyst is denoted as Mn-SA(2h)@MSGO.

[0187] Example 3

[0188] The method and parameters for preparing the denitration catalyst in Example 3 refer to Example 1, the difference being the calcination time in Step 2. The calcination time in Step 2 of this example is 3 h. The obtained catalyst is denoted as Mn-SA(3h)@MSGO.

[0189] Example 4

[0190] The method for preparing the denitration catalyst in Example 4 and the parameters refer to Example 1, except that the calcination time in Step 2 is different. The calcination time in Step 2 of this example is 4 h. The obtained catalyst is denoted as Mn-SA(4h)@MSGO.

[0191] Detection Example

[0192] SCR activity tests were carried out on the catalyst samples Mn-SA@MSGO prepared by the preparation methods of Examples 1 to 4 to explore the influence of different calcination temperatures on SCR activity.

[0193] The simulated gas contains no water and no sulfur. The test conditions 1 are as follows: the reaction temperature is 150 - 300 °C, the test time at each temperature is 1 hour, the gas flow rate is 100 mL / min, the NO concentration is 500 ppm, and the NH 3 concentration is 500 ppm, and the O 2 concentration is 5%, with N 2 as the balance gas and the space velocity of 30000 h -1 .

[0194] SCR denitration activity tests were carried out on the catalysts prepared in Examples 1 to 4 of the present invention. The nitrogen oxide removal rate and nitrogen selectivity are shown in Table 1.

[0195] Table 1 SCR denitration activity and selectivity (%) of Examples 1 - 4 under different experimental conditions

[0196]

[0197]

[0198] See Figure 1 , Figure 1 is the SCR denitration activity diagram of the Mn-SA@MSGO catalyst sample prepared in Example 3 of the present invention.

[0199] As Figure 1 shown, the catalyst prepared by the method provided by the present invention has good denitration activity with a wide temperature window at 180 - 300 °C. Especially at 240 °C, the conversion rate of nitrogen oxides is 99%. At the same time, the catalyst has excellent nitrogen selectivity, and the nitrogen selectivity is above 80% below 270 °C.

[0200] See Figure 2 , Figure 2 is the N 2 selectivity diagram of the Mn-SA@MSGO catalyst sample prepared in Example 3 of the present invention.

[0201] The SCR activity test was carried out on the catalyst sample Mn-SA(3h)@MSGO prepared in Example 3. The simulated gas contained no water and contained sulfur. The test conditions 2 were as follows: the reaction temperature was 240 °C, the reaction time was 12 hours, the gas flow rate was 100 mL / min, the NO concentration was 500 ppm, and the NH 3 concentration was 500 ppm, and the SO 2 concentration was 100 ppm, and the O 2 concentration was 5%, and N 2 was used as the balance gas, and the space velocity was 30000 h -1 .

[0202] See Figure 3 , Figure 3 which is the catalyst activity diagram for the SO 2 resistance test of the Mn-SA@MSGO catalyst sample prepared in Example 3 of the present invention.

[0203] The results are as shown in the appendix Figure 3 and indicate that the catalyst has excellent SO 2 resistance. The conversion rate of NOx was 96% and the selectivity for nitrogen was 85% during the 12-hour monitoring.

[0204] The SCR activity test was carried out on the catalyst sample Mn-SA(3h)@MSGO prepared in Example 3. The simulated gas contained no sulfur and contained water. The test conditions 3 were as follows: the reaction temperature was 240 °C, the reaction time was 12 hours, the gas flow rate was 100 mL / min, the NO concentration was 500 ppm, and the NH 3 concentration was 500 ppm, and the H 2 O volume concentration was 8%, and the O 2 concentration was 5%, and N 2 was used as the balance gas, and the space velocity was 30000 h -1 .

[0205] See Figure 4 , Figure 4 which is the catalyst activity diagram for the H 2 O resistance test of the Mn-SA@MSGO catalyst sample prepared in Example 3 of the present invention.

[0206] The results are as shown in the appendix Figure 4 and indicate that the catalyst has excellent H 2 O resistance. The conversion rate of NO x was 95% and the selectivity for nitrogen was 83% during the 12-hour monitoring.

[0207] The SCR activity of the catalyst sample Mn-SA(3h)@MSGO prepared in Example 3 was tested. The simulated gas contained no water and no sulfur, and a stability test was carried out. Test condition 4 was: reaction temperature 200 °C, reaction time 60 hours, gas flow rate 100 mL / min, NO concentration 500 ppm, NH 3 concentration 500 ppm, O 2 concentration 5%, N 2 as the balance gas, space velocity 30000 h -1 .

[0208] See Figure 5 , Figure 5 which is the catalyst activity diagram of the stability test of the Mn-SA@MSGO catalyst sample prepared in Example 3 of the present invention.

[0209] The results are as shown in the appendix Figure 5 . Under the conditions of no water and no sulfur, a stability test was carried out. Under the monitoring of 60 hours, the conversion rate of NO x was 95%, and the selectivity of nitrogen was 84.5%. The results show that the catalyst has excellent long-term stability.

[0210] According to the above results, the single-atom loaded graphene modified melamine sponge flexible denitration catalyst prepared by the present invention shows good SCR denitration activity (150-300 °C) in the wide temperature window under the anhydrous and sulfur-free conditions of Experimental Example 1, and has excellent nitrogen selectivity. Under the conditions of no water and sulfur-containing, the catalyst can still ensure 96% NO x conversion rate after 12 hours of reaction, and the nitrogen selectivity is 85%. Under the conditions of water-containing and sulfur-free, the catalyst can still maintain 95% NO x conversion rate, and the nitrogen selectivity is 83%. Under the conditions of no water and no sulfur, a stability test was carried out, the reaction time was 24 hours, and the NO x conversion rate was 97%, and the nitrogen selectivity was 84%. The results show that the catalyst has relatively excellent water and sulfur resistance performance and good stability.

[0211] The preparation process of Example 3 of the present invention and the prepared catalyst were characterized.

[0212] Fourier transform infrared analysis was carried out on the catalysts Mn-SA(3h)@MSGO, Mn@ZIF-8, and Mn-SA prepared in this Example 3. See Figure 6 , Figure 6 which is the Fourier transform infrared spectrometer test diagram of the Mn-SA@MSGO catalyst sample prepared in Example 3 of the present invention and Mn-ZIF8, Mn-SA.

[0213] As shown in the appendixFigure 6 As shown, before calcination, Mn-ZIF8 contains a large number of organic functional groups, including C-H, C-O, C-N, C=O bonds, etc. Among them, the metal coordination structure belongs to the Zn-N bond and the Mn-O bond in manganese acetylacetonate. With high-temperature calcination, the Zn-N bond is destroyed by high temperature, Zn volatilizes, and Mn coordinates with nitrogen-containing functional groups to form Mn-N bonds. At the same time, the organic functional groups are carbonized during high-temperature calcination. Mn-N bonds are commonly found in coordination compounds or single-atom catalysts supported on nitrogen-doped materials (such as nitrogen-doped carbon materials, nitrogen ligands). The presence of Mn-N bonds not only provides a stable coordination structure but also can regulate the electron density of Mn, enhancing the adsorption and activation of NO x The adsorption and activation effect. Compared with the Mn-O bond, the Mn-N bond is less sensitive to sulfur oxides because sulfur oxides tend to react with oxygen to form sulfates. Due to the presence of Mn-N bonds, the SO 2 adsorption on the oxide surface can be reduced, so the sulfur resistance of the catalyst can be improved to a certain extent.

[0214] Raman spectroscopy tests were carried out on the catalysts Mn-SA(3h)@MSGO and Mn-SA prepared in Example 3. See Figure 7 , Figure 7 This is the Raman spectrometer test diagram of the Mn-SA@MSGO catalyst sample and Mn-SA prepared in Example 3 of the present invention.

[0215] As shown in the appendix Figure 7 The catalyst sample prepared by the present invention simultaneously has the characteristic peaks of the original melamine sponge and graphene oxide. Compared with Mn-SA, Mn-SA@MSGO has a higher G peak position, indicating that it is loaded on the MSGO support and has a higher degree of graphitization. High graphitization means efficient electron transfer and electrochemical performance, which also promotes the redox process in SCR.

[0216] Scanning electron microscopy analysis was carried out on Mn-SA(3h)@MSGO prepared in Example 3. See Figure 8 , Figure 8 This is the micrograph of the Mn-SA@MSGO catalyst sample prepared in Example 3 of the present invention.

[0217] As shown in the appendix Figure 8 The graphene oxide is evenly loaded on the melamine sponge framework, and the metal active component particles are evenly distributed on its surface.

[0218] The above has provided a detailed introduction to a single-atom flexible denitration catalyst with high efficiency in water and sulfur resistance and its preparation method. In this article, specific examples are used to elaborate on the principle and implementation manner of the present invention. The description of the above embodiments is only used to help understand the method and its core idea of the present invention, including the best mode, and also enables any person skilled in the art to practice the present invention, including manufacturing and using any device or system, and implementing any combined method. It should be noted that for those of ordinary skill in the art in the technical field, without departing from the principle of the present invention, several improvements and modifications can be made to the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention. The protection scope of the present invention patent is defined by the claims and may include other embodiments that can be conceived by those skilled in the art. If these other embodiments have structural elements that are not different from the literal description of the claims, or if they include equivalent structural elements that have no substantial difference from the literal description of the claims, then these other embodiments should also be included within the scope of the claims.

Claims

1. A single-atom flexible denitration catalyst, characterized in that: It includes a graphene oxide / melamine sponge composite carrier and a single-atom active component loaded on the composite carrier; The active components include manganese, cobalt, cerium or iron.

2. The denitration catalyst according to claim 1, characterized in that: The graphene oxide / melamine sponge composite carrier is specifically graphene oxide attached to melamine sponge; The single-atom active component is specifically an active component complex in which a single atom of the active component is supported on a nitrogen-doped carbon framework; In the denitration catalyst, the content of active components is 0.2wt% to 5wt%.

3. The denitration catalyst according to claim 2, characterized in that: In the graphene oxide / melamine sponge composite carrier, the loading amount of graphene oxide is 10wt% to 50wt%; The mass of the active component composite is 20% to 50wt% of the mass of the graphene oxide / melamine sponge composite carrier; The porosity of the melamine sponge is 90% to 99%; The single-atom flexible denitration catalyst is specifically a single-atom flexible denitration catalyst that is resistant to water and sulfur.

4. The denitration catalyst according to claim 2, characterized in that: The nitrogen-doped carbon framework is obtained by calcining a metal organic framework material; The metal organic framework material includes ZIF-8; The calcination temperature is 600-1000°C; The calcination time is 1 to 4 hours; The single-atom flexible denitration catalyst is a catalyst used in an NH3-SCR denitration system.

5. A method for preparing a single-atom flexible denitration catalyst, characterized in that: The following steps are involved: 1) Under a protective atmosphere, calcining a metal organic framework material loaded with an active component metal source to obtain an active component composite; The melamine sponge is immersed in a graphene oxide suspension, and after drying, a modified melamine sponge with graphene oxide attached is obtained; 2) The modified melamine sponge is immersed in a solution of the active component complex and heated to react to obtain a single-atom flexible denitrification catalyst.

6. The preparation method according to claim 5, characterized in that: The method for preparing the metal organic framework material loaded with an active component metal source comprises the following steps: a) dissolving an active component metal source and zinc nitrate hexahydrate in a first solvent to obtain a solution A; dissolving an organic precursor of a metal organic framework material in a second solvent to obtain a solution B; b) The solution A and the solution B obtained in the above step are mixed and reacted to obtain a metal organic framework material loaded with an active component metal source.

7. The preparation method according to claim 6, characterized in that: The metal source includes a soluble organic metal source and / or a soluble inorganic metal salt; The organic precursor of the metal organic framework material includes 2-methylimidazole; The molar ratio of the active component metal source to zinc nitrate hexahydrate, calculated as metal elements, is 1:(1-5); The molar ratio of the active component metal source, calculated as metal element, to the organic precursor of the metal organic framework material is 1:(5-20).

8. The preparation method according to claim 6, characterized in that: The metal source includes acetylacetonate metal compound and / or metal nitrate; The first solvent and the second solvent are each independently selected from methanol and / or ethanol; In the step b), the reaction temperature is 15 to 120°C; In the step b), the reaction time is 3 to 12 hours.

9. The preparation method according to claim 5, characterized in that: The calcination temperature is 600-1000°C; The calcination time is 1 to 4 hours; In the step 1), the immersion time is 30 to 120 minutes; In the modified melamine sponge, graphene oxide is evenly distributed in the melamine sponge.

10. The preparation method according to claim 5, characterized in that: The solvent of the solution of the active component complex includes methanol and / or ethanol; In the step 2), after immersing, the modified melamine sponge is further subjected to repeated squeezing; The temperature of the heating reaction is 50-90°C; The heating reaction time is 2 to 12 hours.

Images