Cobalt-containing zeolite, and preparation method therefor and use thereof

Abstract

Provided are a cobalt-containing zeolite, and a preparation method therefor and the use thereof. The cobalt-containing zeolite at least comprises silicon, aluminum and oxygen as framework atoms, wherein the molar ratio of silicon atoms to aluminum atoms is 2-100:1, and on the basis of the total mass of the cobalt-containing zeolite, the mass proportion of cobalt is greater than or equal to 0.1%. When the cobalt-containing zeolite is analyzed by means of 29Si solid-state nuclear magnetic resonance spectroscopy, the peak area in the chemical shift interval of -110 ppm to -90 ppm accounts for 35-85% of the peak area in the chemical shift interval of -125 ppm to -90 ppm. The present application at least solves the problem of the severe deactivation of a catalyst in a temperature interval of 300°C or lower when alcohol is used as a reducing agent for selective catalytic reduction denitration in a high-sulfur-content atmosphere, thereby solving the problem of a low denitration treatment efficiency of industrial flue gas at a relatively low discharge temperature in a high-sulfur-content atmosphere.

Description

Cobalt-containing zeolites, their preparation methods and applications

[0001] Cross-references to related applications

[0002] This application claims the benefit and priority of Chinese Patent Application No. 202510068903.1, filed with the China National Intellectual Property Administration on January 16, 2025, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This application belongs to the field of denitrification catalysis, specifically relating to a cobalt-containing zeolite, its preparation method, and its application. Background Technology

[0004] Nitrogen oxides (NO) x Nitrogen oxides (NOx) are highly irritating and corrosive, harming human health and readily interacting with other harmful compounds to form sulfates, nitrates, and other harmful substances, making them a major culprit in atmospheric smog. Selective catalytic reduction (SCR) is currently the primary flue gas denitrification technology. It utilizes a reducing agent, under the action of a catalyst, to selectively react with nitrogen oxides in flue gas to produce nitrogen and water, thereby removing nitrogen oxides. However, when treating industrial waste gas from high-sulfur fuel industries such as coal and heavy oil, these fuels generate a certain amount of sulfur oxides during industrial processes. In flue gas denitrification processes using ammonia as a reducing agent, sulfur oxides often react with the reducing agent ammonia to form ammonium sulfate byproducts. Because ammonium sulfate is corrosive and sticky, it easily adheres to surfaces, leading to catalyst deactivation and equipment malfunctions.

[0005] Using lower alcohols as reducing agents avoids the formation of deposits by reacting with sulfur oxides. Furthermore, liquid lower alcohols (alcohol-SCR) are easier to store safely than ammonia and do not cause pipeline blockages due to urea precipitation at low temperatures, as is the case with urea solutions. Although using alcohols instead of ammonia avoids ammonium sulfate formation, at low temperatures (below 300°C), sulfur oxides can easily adsorb onto or react with the active sites in the alcohol-SCR catalyst, leading to severe deactivation of the catalyst. Summary of the Invention

[0006] The inventors of this application have conducted in-depth research on the technical problems existing in this field and have discovered that one or more of the above-mentioned technical problems can be solved by the following technical solutions.

[0007] According to the first aspect of this application, a cobalt-containing zeolite is proposed, wherein the cobalt-containing zeolite contains at least silicon, aluminum, and oxygen as framework atoms, wherein the molar ratio of silicon atoms to aluminum atoms is 2 to 100:1, and based on the total mass of the cobalt-containing zeolite, the mass percentage of cobalt is greater than or equal to 0.1%. The cobalt-containing zeolite is treated with... 29 When analyzing the nuclear magnetic resonance spectrum of Si solid, the peak area in the chemical shift range of -110 ppm to -90 ppm accounts for 35%-85% of the peak area in the chemical shift range of -125 ppm to -90 ppm.

[0008] In some embodiments, the cobalt-containing zeolite is a cobalt-containing FER-type zeolite.

[0009] In some embodiments, the mass percentage of cobalt is 0.1%-7%, preferably 0.1%-5%, based on the total mass of the cobalt-containing zeolite.

[0010] According to the second aspect of this application, a method for preparing the cobalt-containing zeolite described in the first aspect of this application is proposed, comprising: mixing and heating a silicon source, an aluminum source, a cobalt source and an inorganic alkali to obtain crystalline zeolite; and removing alkali metal ions from the zeolite to obtain cobalt-containing zeolite.

[0011] In some embodiments, an organic template agent is added before heating the silicon source, the aluminum source, the cobalt source, and the inorganic base to obtain crystalline zeolite.

[0012] According to the third aspect of this application, another method for preparing the cobalt-containing zeolite described in the first aspect of this application is proposed, comprising: mixing and heating a silicon source, an aluminum source and an inorganic alkali to obtain crystalline zeolite; removing alkali metal ions from the zeolite by ion exchange, and then introducing cobalt ions into the zeolite after removing the alkali metal ions by ion exchange; mixing the zeolite with introduced cobalt ions with cobalt oxide to obtain cobalt-containing zeolite.

[0013] In some embodiments, an organic template agent is added before the silicon source, the aluminum source, and the inorganic base are mixed and heated to obtain crystalline zeolite.

[0014] According to the fourth aspect of this application, the use of cobalt-containing zeolite as described in the first aspect of this application or cobalt-containing zeolite obtained by the method described in the second or third aspect of this application as a denitrification catalyst in selective catalytic reduction denitrification using alcohol as a reducing agent is proposed.

[0015] In some embodiments, the alcohol contains 1-6 carbon atoms.

[0016] According to the fifth aspect of this application, a catalytic reactor for purifying nitrogen oxides is proposed, the catalytic reactor comprising a denitrification catalyst, the denitrification catalyst comprising the cobalt-containing zeolite described in the first aspect of this application or the cobalt-containing zeolite prepared according to the methods described in the second or third aspect of this application.

[0017] According to the sixth aspect of this application, a nitrogen oxide purification system is proposed, wherein the system is provided with the catalytic reactor for nitrogen oxide purification described in the fifth aspect of this application.

[0018] According to the seventh aspect of this application, a denitrification method is proposed, comprising using a denitrification catalyst to selectively catalytically reduce denitrification with an alcohol as a reducing agent, wherein the denitrification catalyst comprises the cobalt-containing zeolite described in the first aspect of this application or the cobalt-containing zeolite prepared according to the method described in the second or third aspect of this application.

[0019] This application at least solves the problem of severe catalyst deactivation in the temperature range below 300°C when selective catalytic reduction denitrification is carried out with alcohol as a reducing agent under high sulfur atmosphere, thereby solving the problem of low denitrification efficiency of industrial flue gas in high sulfur atmosphere and low emission temperature. Attached Figure Description

[0020] The embodiments illustrated herein are further described below with reference to the accompanying drawings, which are provided merely to enable those skilled in the art to better understand the invention and are not intended to limit the scope of the invention.

[0021] Figure 1 shows zeolite A prepared according to Example 1 of this application. 29 Si solid-state nuclear magnetic resonance spectrum;

[0022] Figure 2 is an XRD pattern of zeolite A prepared according to Example 1 of this application;

[0023] Figure 3 shows zeolite B prepared according to Example 2 of this application. 29 Si solid-state nuclear magnetic resonance spectrum;

[0024] Figure 4 is an XRD pattern of zeolite B prepared according to Example 2 of this application;

[0025] Figure 5 shows the zeolite C prepared according to Example 3 of this application. 29 Si solid-state nuclear magnetic resonance spectrum;

[0026] Figure 6 is an XRD pattern of zeolite C prepared according to Example 3 of this application;

[0027] Figure 7 shows zeolite D prepared according to Example 4 of this application. 29 Si solid-state nuclear magnetic resonance spectrum;

[0028] Figure 8 is an XRD pattern of zeolite D prepared according to Example 4 of this application;

[0029] Figure 9 shows zeolite E prepared according to Example 5 of this application. 29 Si solid-state nuclear magnetic resonance spectrum;

[0030] Figure 10 is an XRD pattern of zeolite E prepared according to Example 5 of this application;

[0031] Figure 11 shows zeolite F prepared according to Example 6 of this application. 29 Si solid-state nuclear magnetic resonance spectrum;

[0032] Figure 12 is an XRD pattern of zeolite F prepared according to Example 6 of this application;

[0033] Figure 13 shows the zeolite G prepared according to Example 7 of this application. 29 Si solid-state nuclear magnetic resonance spectrum;

[0034] Figure 14 is an XRD pattern of zeolite G prepared according to Example 7 of this application;

[0035] Figure 15 shows the zeolite H prepared according to Example 8 of this application. 29 Si solid-state nuclear magnetic resonance spectrum;

[0036] Figure 16 is an XRD pattern of zeolite H prepared according to Example 8 of this application;

[0037] Figure 17 shows zeolite I prepared according to Example 9 of this application. 29 Si solid-state nuclear magnetic resonance spectrum;

[0038] Figure 18 is an XRD pattern of zeolite I prepared according to Example 9 of this application;

[0039] Figure 19 shows zeolite J prepared according to Example 10 of this application. 29 Si solid-state nuclear magnetic resonance spectrum;

[0040] Figure 20 is an XRD pattern of zeolite J prepared according to Example 10 of this application;

[0041] Figure 21 shows zeolite K prepared according to Comparative Example 1 of this application. 29 Si solid-state nuclear magnetic resonance spectrum;

[0042] Figure 22 is an XRD pattern of zeolite K prepared according to Comparative Example 1 of this application;

[0043] Figure 23 shows the zeolite L prepared according to Comparative Example 2 of this application. 29 Si solid-state nuclear magnetic resonance spectrum;

[0044] Figure 24 is the XRD pattern of zeolite L prepared according to Comparative Example 2 of this application;

[0045] Figure 25 shows zeolite M prepared according to Comparative Example 3 of this application. 29 Si solid-state nuclear magnetic resonance spectrum;

[0046] Figure 26 shows zeolite M prepared according to Comparative Example 3 of this application. 29 Si solid-state nuclear magnetic resonance spectrum;

[0047] Figure 27 shows the zeolite N prepared according to Comparative Example 4 of this application. 29 Si solid-state nuclear magnetic resonance spectrum;

[0048] Figure 28 is an XRD pattern of zeolite N prepared according to Comparative Example 4 of this application;

[0049] Figure 29 shows zeolite O prepared according to Comparative Example 5 of this application. 29 Si solid-state nuclear magnetic resonance spectrum;

[0050] Figure 30 is an XRD pattern of zeolite O prepared according to Comparative Example 5 of this application;

[0051] Figure 31 shows zeolite P prepared according to Comparative Example 6 of this application. 29 Si solid-state nuclear magnetic resonance spectrum;

[0052] Figure 32 is an illustration. 29 A schematic diagram showing the relationship between the chemical shift of Si and the state of Si in the nuclear magnetic resonance spectrum of Si solid. Detailed Implementation

[0053] The inventive concept of this application will be further described below with reference to specific embodiments. However, the specific embodiments listed are for illustrative purposes only and are not intended to limit the scope of this application. Those skilled in the art will recognize that specific features in any of the following embodiments can be used in any other embodiments, as long as they do not depart from the inventive concept described herein.

[0054] zeolite

[0055] The zeolites mentioned in this article refer to those defined by the International Zeolite Association (IZA), such as FER-type zeolites, MFI-type zeolites, and FAU-type zeolites. Zeolites are typically composed of a regular mesh-like structure formed by oxygen atoms at the vertices of framework tetrahedra (such as SiO4 tetrahedra, AlO4 tetrahedra, or PO4 tetrahedra) linked together. Elements other than oxygen are usually referred to as non-oxygen atoms or T atoms.

[0056] The cobalt-containing zeolite provided herein contains at least oxygen, aluminum, and silicon as atoms constituting the framework structure, and a portion of the framework atoms can be replaced by one or more elements other than the aforementioned three elements. In one embodiment of this application, the molar ratio of silicon atoms to aluminum atoms is 2 to 100:1, for example 2:1, 5:1, 10:1, 15:1, 20:1, 30:1, 40:1, 50:1, 60:1, 70:1, 80:1, 90:1, or 100:1, etc., or can be any range of the above values.

[0057] The cobalt-containing zeolite described in this article uses... 29 When analyzing the NMR spectrum of Si solid-state, the peak area in the -110 ppm to -90 ppm chemical shift range accounts for 35%-85% of the peak area in the -125 ppm to -90 ppm chemical shift range, for example, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, or 85%, etc., or any range of the above values. Studies have found that zeolites with the above characteristics maintain high catalytic activity in alcohol-SCR denitration under high sulfur atmospheres. It is generally believed that... 29 The characteristic peaks in the -110ppm to -90ppm chemical shift range of the Si solid-state NMR spectrum reflect information about the skeletal silicon connected to the framework Al phase. The higher the area of ​​the absorption peaks in this range, the more characteristic acid active sites the zeolite has, thus resulting in higher alcohol-SCR catalytic activity of cobalt-containing zeolites.

[0058] For cobalt-containing zeolites 29 The chemical shifts of Si in the solid-state NMR spectrum reflect the local state of silicon atoms, that is, they can reveal the chemical morphology of Si in cobalt-containing zeolites. Specifically, the applicant has provided a schematic diagram to illustrate this. 29 The relationship between the chemical shift of Si and the state of Si in the NMR spectrum of Si solid-state is shown in Figure 32. The chemical environment of Si is represented by Q. n (Q 0 -Q 4 ) represents the number of oxygen atoms shared by each silicon-oxygen tetrahedron with its adjacent tetrahedra. Q 0 Q represents a monomer. 1 Q represents the end of a dimer or long chain (with a shared oxygen atom). 2 This refers to Si, Q, which has two shared oxygen atoms in the middle of the silicon chain. 3 Si, Q represents a silicon chain branch with three shared oxygen atoms. 4 This indicates a network structure (with four shared oxygen atoms). In the Si NMR spectrum, Q 0 The corresponding chemical shift is -68ppm to -76ppm, Q 1The corresponding chemical shift is -76ppm to -82ppm, Q 2 The corresponding chemical shift is -82ppm to -88ppm, Q 3 The corresponding chemical shift is -88ppm to -98ppm, Q 4 The corresponding chemical shift is -98 ppm to -129 ppm. Therefore, cobalt-containing zeolites... 29 In the NMR spectrum of Si solid, the size of the Si NMR signal area at different chemical shifts indicates the amount of Si atoms with specific structures in the zeolite.

[0059] In the cobalt-containing zeolite described herein, the location and specific chemical valence state of cobalt within the zeolite are not particularly limited. Cobalt can be present in the zeolite framework or outside of it. In some embodiments of this application, cobalt is present outside the zeolite framework. In some embodiments of this application, based on the total mass of the cobalt-containing zeolite, the mass percentage of cobalt is greater than or equal to 0.1%, for example, 0.1%, 0.3%, 0.5%, 1%, 1.5%, 2.5%, 3%, 4%, 5%, 6%, 7%, 8%, or 10%. In other embodiments of this application, based on the total mass of the cobalt-containing zeolite, the mass percentage of cobalt is 0.1%-7%, further 0.1%-5%. Thus, by loading the cobalt-containing zeolite with the above-mentioned amounts of cobalt, the problem of severe deactivation during the denitrification process in the temperature range below 300°C can be significantly reduced.

[0060] In some embodiments of this application, the cobalt-containing zeolite is a cobalt-containing FER-type zeolite. Specifically, the structure of the cobalt-containing FER-type zeolite can be determined by X-ray diffraction (XRD), requiring at least the interplanar spacings shown in Table 1 below to be detected. That is, if the interplanar spacing is as shown in Table 1 below, the zeolite can be a cobalt-containing FER type zeolite.

[0061] Table 1

[0062] Methods for preparing cobalt-containing zeolites

[0063] This application provides a method for preparing the cobalt-containing zeolite described above, comprising mixing and heating a silicon source, an aluminum source, a cobalt source and an inorganic alkali to obtain crystalline zeolite, and then removing alkali metal ions from the zeolite to obtain cobalt-containing zeolite.

[0064] In some embodiments of this application, the method of mixing and heating silicon source, aluminum source, cobalt source and inorganic base can be a hydrothermal synthesis method. The raw materials are prepared into an aqueous gel with water and then placed in a reaction vessel for hydrothermal synthesis reaction to obtain crystalline zeolite.

[0065] The raw materials used in the manufacturing process of cobalt-containing zeolite described in this article mainly include silicon source, aluminum source, cobalt source, inorganic alkali, and water. Organic template agents may also be included. In addition, components with crystallization-promoting effects, such as seed crystals, may also be added.

[0066] In some embodiments of this application, the silicon source may be one or more of colloidal silica, amorphous silica, fumed silica, silica, water glass (sodium silicate), trimethylethoxysilane, tetraethyl orthosilicate, aluminum silicate gel, etc.

[0067] In some embodiments of this application, if the silicon source is liquid, it can be used as long as it is formulated into an aqueous dispersion of silica at approximately 5% to 60% by weight, similar to silica gel. When preparing other liquids containing a silicon source, it is preferable to prepare an aqueous solution or dispersion with a silicon source concentration of 5% by weight or more, particularly 10% by weight or more, and 60% by weight or less, particularly 50% by weight or less. This liquid silicon source substantially does not contain aluminum atoms. Here, "substantially does not contain" means that the aluminum content in the liquid containing the silicon source is 1% by weight or less, preferably completely absent.

[0068] In some embodiments of this application, the aluminum source may be one or more of aluminum sulfate, aluminum nitrate, sodium aluminate, sodium aluminate, alumina, aluminum hydroxide, boehmite, aluminum chloride, aluminum silicate gel, metallic aluminum, etc., preferably a water-soluble aluminum source.

[0069] In some embodiments of this application, when preparing the crystalline zeolite described above, the aluminum source can be prepared as a solution, preferably by dissolving the aluminum source in water. The concentration of the aluminum source solution can be 5% to 50% by weight, considering ease of gel preparation and production efficiency, for example, 5% by weight, 10% by weight, 15% by weight, 20% by weight, 25% by weight, 30% by weight, 35% by weight, 40% by weight, 45% by weight, or 50% by weight, or a range of any of the above values. Further, the concentration of the aluminum source solution is 10% by weight to 40% by weight.

[0070] It should be noted that this aluminum source solution does not actually contain silicon atoms. Here, "actually does not contain" means that the silicon content in the aluminum source solution is less than 1% by weight, preferably completely absent.

[0071] In some embodiments of this application, the cobalt source may be one or more of cobalt nitrate, cobalt sulfate, cobalt carbonate, cobalt chloride, cobalt hydroxide, cobalt oxalate, cobalt acetate, cobalt oxide, cobalt tetroxide, high cobalt oxide, high cobalt hydroxide, lithium cobalt oxide, sodium hexanitrocobaltate, etc.

[0072] In some embodiments of this application, when preparing the crystalline zeolite described above, the cobalt source can be prepared as a solution. For example, the cobalt source can be dissolved in a liquid to prepare a cobalt source solution, such as water, or an organic solvent, which may include one or more organic solvents such as methanol, ethanol, ethylene glycol, glycerol, and toluene. In some embodiments of this application, the pH value of the cobalt source solution is typically 1 to 14, for example, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, or 14, or any range of the above values. Further, the pH value of the cobalt source solution can be 1 to 13, and even further, 2 to 12. This is because cobalt source solutions with lower or higher pH values ​​are more likely to cause damage or collapse of the zeolite framework during mixing, resulting in reduced denitrification activity and thermal stability of the prepared cobalt-containing zeolite.

[0073] In some embodiments of this application, the metal cation of the inorganic base may include alkali metal ions and / or alkaline earth metal ions, preferably using at least one metal ion selected from the group consisting of lithium, sodium, potassium, rubidium, cesium, calcium, magnesium, strontium, and barium for crystallization. By using an inorganic base containing these alkali metal ions and / or alkaline earth metal ions, crystallization is easier and less likely to generate byproducts (impurity crystals). It should be noted that when calculating the molar ratio of components in the gel, the molar ratio is generally calculated using the corresponding oxide A2O of the inorganic base AOH. In some embodiments of this application, the inorganic base may be one or more of alkali metal hydroxides such as sodium hydroxide, potassium hydroxide, rubidium hydroxide, cesium hydroxide, the alkaline component in the aluminates of the aforementioned aluminum raw materials, the silicates of the aforementioned silicon raw materials, or the alkaline component in silicate gels.

[0074] In some embodiments of this application, an organic template agent may be added during the preparation of the crystalline zeolite described above. Specifically, an organic template agent is added before mixing and heating the silicon source, the aluminum source, the cobalt source, and the inorganic base to obtain the crystalline zeolite. For example, the organic template agent may include one or more of the following: ethylenediamine, isopropylamine, butylamine, octanediamine, cyclohexylimine, tetramethylammonium hydroxide, pyrrolidine, morpholine, N-methylmorpholine, piperidine, piperazine, N,N'-dimethylpiperazine, 1,4-diazabicyclo(2,2,2)octane, N-methylpiperidine, 3-methylpiperidine, quinine ring, N-methylpyrrolidone and hexamethyleneimine, methanol, ethanol, ethylene glycol, propanol, glycerol, and isopropanol.

[0075] In some embodiments of this application, an inorganic alkaline solution, a silicon source solution, an aluminum source solution, and a cobalt source solution can be uniformly mixed and heated to prepare an aqueous gel. In other embodiments of this application, an inorganic alkaline solution, a silicon source solution, an aluminum source solution, a cobalt source solution, and an organic template agent can be uniformly mixed and heated to prepare an aqueous gel. It should be noted that there is no limitation on the addition rate of each raw material solution during the preparation of the above-mentioned aqueous gel; it can be appropriately selected according to the usage conditions.

[0076] In some embodiments of this application, the water content of the aqueous gel supplied to the hydrothermal synthesis reaction is 20% by weight or more, particularly 30% by weight or more and 80% by weight or less, particularly 70% by weight or less, considering the ease of zeolite crystal formation and manufacturing cost. The aqueous gel prepared as described above can be hydrothermally synthesized immediately after preparation; however, to obtain zeolite with high crystallinity, it is preferable to mature it for a specific time under specified temperature conditions. The maturation temperature is typically below 100°C, preferably below 80°C, more preferably below 60°C, and its lower limit is not particularly limited, but is typically above 0°C, preferably above 10°C; for example, maturation can be carried out at room temperature (25°C). The maturation temperature can be constant or gradually varied during maturation. The maturation time is not particularly limited, but is typically 2 hours or more, 3 hours or more, 5 hours or more, 8 hours or more, or 12 hours or more, and typically less than 30 days, less than 10 days, less than 4 days, less than 2 days, or less than 24 hours.

[0077] In some embodiments of this application, hydrothermal synthesis can be carried out as follows: the aqueous gel obtained by the above operation is placed in a pressure-resistant container, and hydrothermal synthesis is carried out under self-generated pressure or gas pressure that does not hinder crystallization, under stirring conditions, or under conditions where the container is rotated or swung, or under a static state, while maintaining the temperature.

[0078] In some embodiments of this application, the reaction temperature during hydrothermal synthesis can be 90°C or higher, preferably 120°C or higher, more preferably 150°C or higher, and further, the reaction temperature during hydrothermal synthesis can be 300°C or lower, preferably 250°C or lower, and even more preferably 220°C or lower. The reaction time is not particularly limited and can be 2 hours or more, 6 hours or more, 12 hours or more, or 24 hours or more, and further, 30 days or less, 10 days or less, 7 days or less, 5 days or less, or 3 days or less. The reaction temperature can be constant or gradually varied during the reaction.

[0079] Following the hydrothermal synthesis described above, the zeolite product is separated from the hydrothermal synthesis reaction solution to obtain zeolite, which may contain one or more organic template agents and / or alkali metals within its pores. There are no particular limitations on the method for separating zeolite from the hydrothermal synthesis reaction solution; methods such as filtration, decantation, or direct drying are commonly used.

[0080] To remove organic templates and / or alkali metal ions used in the manufacturing process, the zeolite separated and recovered from the hydrothermal synthesis reaction solution can be washed with water and dried (e.g., dried at 80°C to 100°C for 1 to 12 hours) as needed for further removal of organic templates and / or alkali metal ions.

[0081] In some embodiments of this application, the removal of organic template agents and / or alkali metals can be achieved using acidic solutions, liquid-phase treatment with chemical solutions containing decomposition components of the organic template agent, ion exchange treatment using resins, thermal decomposition treatment, or a combination of these treatments. Generally, the organic matter (organic template agent) can be removed by calcination in air or an oxygen-containing inert gas atmosphere, or by extraction using organic solvents such as aqueous ethanol solutions.

[0082] In some embodiments of this application, calcination can be used to remove organic template agents, etc., wherein the calcination temperature is preferably 400°C or higher, more preferably 450°C or higher, further preferably 500°C or higher, preferably 900°C or lower, more preferably 850°C or lower, and further preferably 800°C or lower. During the calcination process, an inactive gas can be introduced, such as nitrogen, or inactive components such as water vapor (e.g., 5% to 10% by volume of water vapor) can be added to the gas.

[0083] In some embodiments of this application, another method for preparing the cobalt-containing zeolite described above is provided, comprising mixing and heating a silicon source, an aluminum source and an inorganic alkali to obtain crystalline zeolite; removing alkali metal ions from the zeolite by ion exchange, and then introducing cobalt ions into the zeolite after removing the alkali metal ions by ion exchange; mixing the zeolite with introduced cobalt ions with cobalt oxide to obtain cobalt-containing zeolite.

[0084] In some embodiments of this application, an organic template agent may be added during the preparation of the crystalline zeolite described above. Specifically, a silicon source, an aluminum source, and an inorganic base are mixed and heated, and an organic template agent is added to obtain crystalline zeolite.

[0085] In some embodiments of this application, the removal of alkali metal ions from zeolite can be achieved by utilizing the ion exchange capacity of zeolite to remove the alkali metals, while simultaneously transforming the zeolite into H-type or ammonium-type zeolite. This can be accomplished using known techniques. For example, ammonium salts such as NH4NO3, NH4Cl, or (NH4)2SO4 can be mixed with zeolite at room temperature to 100°C and then washed with water to obtain ammonium-type zeolite; alternatively, acidic solutions such as hydrochloric acid can be mixed with zeolite at room temperature to 100°C and then washed with water to obtain H-type zeolite.

[0086] In some embodiments of this application, ammonium-type zeolite can be further converted into H-type zeolite through calcination. The calcination temperature is preferably 300°C or higher, more preferably 350°C or higher, even more preferably 400°C or higher, preferably 900°C or lower, more preferably 800°C or lower, and even more preferably 600°C or lower. An inactive gas is introduced during the calcination process; gases such as nitrogen can be used, or inactive components such as water vapor (e.g., 5% to 10% by volume of water vapor) can be added to the gas. Both ammonium-type and H-type zeolite can be used to prepare cobalt-containing FER zeolite.

[0087] In some embodiments of this application, the introduction of cobalt ions into zeolite after the removal of alkali metal ions via ion exchange is obtained by mixing a cobalt source solution with the zeolite after the removal of alkali metal ions. The cobalt source solution is prepared by dissolving the cobalt source in a liquid to form a cobalt-containing solution. The cobalt source can be dissolved in water or in an organic solvent, such as one or more of methanol, ethanol, ethylene glycol, glycerol, toluene, etc. The pH value of the cobalt-containing solution is typically 1–14, preferably 1–13, and more preferably 2–12. This is because cobalt-containing solutions with low or high pH values ​​are prone to causing damage or collapse of the zeolite framework during mixing, resulting in reduced denitrification activity and thermal stability of the prepared catalyst.

[0088] In some embodiments of this application, the mixing method between the zeolite after alkali metal ion removal and the cobalt-containing solution is not particularly limited. Stirring, ultrasonication, or other methods can typically be used to ensure uniform mixing. The mixing temperature is usually between room temperature and 100°C, preferably between room temperature and 80°C, and more preferably between 50°C and 80°C. The method for separating the zeolite after mixing is not particularly limited; filtration, rotary evaporation, or direct drying are commonly used.

[0089] In some embodiments of this application, the zeolite incorporating cobalt ions may or may not be calcined after separation. Preferably, the zeolite incorporating cobalt ions is calcined after separation. The calcination temperature is preferably 300°C or higher, more preferably 350°C or higher, further preferably 400°C or higher, preferably 900°C or lower, more preferably 800°C or lower, and further preferably 600°C or lower. The calcination time can be from 1 hour to 6 hours, for example, 2 hours, 3 hours, 4 hours, or 5 hours. An inactive gas, such as nitrogen, may be introduced during the calcination process, or inactive components such as water vapor (e.g., 5% to 10% by volume of water vapor) may be added to the gas.

[0090] In some embodiments of this application, zeolite incorporating cobalt ions is mixed with cobalt oxide to obtain cobalt-containing zeolite. Cobalt oxide helps to further reduce nitrogen oxides from carbon monoxide generated in the alcohol-SCR reaction, thereby enhancing the denitrification activity of the catalyst.

[0091] In some embodiments of this application, the method of mixing the cobalt ion-introduced zeolite with the cobalt oxide is not particularly limited. For example, the cobalt ion-introduced zeolite powder and the cobalt oxide powder can be ground separately and then physically mixed; alternatively, they can be physically mixed and then ground. Binders such as silicon oxide, aluminum oxide, or zirconium oxide can also be added during the mixing process. The cobalt oxide can include one or more of cobalt oxide, cobalt trioxide, and cobalt tetroxide.

[0092] It should be noted that the amount of cobalt oxide added is based on the mass percentage of cobalt element in the final cobalt-containing zeolite being higher than or equal to 0.1%, preferably 0.1%-7%, and more preferably 0.1%-5%.

[0093] The roasting equipment used in this application is not particularly limited, and common industrial kilns such as muffle furnaces, tunnel kilns, or rotary kilns can be used. Considering the convenience of continuous production, rotary kilns are preferred.

[0094] It should be noted that the above-mentioned methods for selecting silicon sources, aluminum sources, cobalt sources, inorganic bases, and organic template agents, as well as the removal of organic template agents, are also applicable to this method for preparing cobalt-containing zeolites, and will not be repeated here.

[0095] Applications of cobalt-containing zeolites

[0096] The cobalt-containing zeolite of this application can be used directly in powder form or mixed with an adhesive to form a mixture containing cobalt-containing zeolite for use. The adhesive used typically includes inorganic adhesives such as silica, alumina, and zirconium oxide, or polysiloxane-based organic adhesives. Polysiloxane-based organic adhesives refer to oligomers or polymers with polysiloxane bonds in their main chain, and also include substances in which a portion of the substituents in the main chain of the polysiloxane bonds is hydrolyzed to form hydroxyl groups. The amount of adhesive used is not particularly limited. For example, based on the total mass of the adhesive and the cobalt-containing zeolite, the amount of adhesive can be 1% to 20% by weight, such as 1%, 5%, 10%, 15%, 20%, etc., or it can be any range of the above values. Considering the strength during molding, the amount of adhesive is 2% to 15% by weight of the total mass of the adhesive and the cobalt-containing zeolite.

[0097] The cobalt-containing zeolite or mixtures thereof of this application can also be used after granulation or molding. There are no particular limitations on the granulation or molding method; various known methods can be employed. Typically, the cobalt-containing zeolite mixture is molded and used as a molded body. The shape of the molded body can be varied. For example, when the cobalt-containing zeolite of this application is used as a catalyst for purifying nitrogen oxides in exhaust gas from mobile sources (vehicles, ships, etc.), the method of applying the cobalt-containing zeolite can be a coating method or a molding method to mold the cobalt-containing zeolite into a honeycomb catalyst. The coating method typically involves mixing the cobalt-containing zeolite with inorganic binders such as silica, alumina, or zirconium oxide to form a slurry, then coating it onto the surface of a honeycomb structure made of inorganic materials such as cordierite, followed by drying and firing. The molding method typically involves mixing the cobalt-containing zeolite with inorganic binders such as silica and alumina, or inorganic fibers such as alumina fibers or glass fibers, molding it into a honeycomb structure by extrusion or compression, and then drying and firing.

[0098] In some embodiments of this application, this application provides the use of the above-mentioned cobalt-containing zeolite or the cobalt-containing zeolite prepared according to the above method as a denitrification catalyst in selective catalytic reduction denitrification using alcohol as a reducing agent.

[0099] In some embodiments of this application, a catalytic reactor for purifying nitrogen oxides is provided. The catalytic reactor includes a denitrification catalyst, which includes cobalt-containing zeolite as described in any of the foregoing embodiments or cobalt-containing zeolite prepared according to the method described in any of the foregoing embodiments.

[0100] In some embodiments of this application, a nitrogen oxide purification system is provided, which includes the aforementioned catalytic reactor for nitrogen oxide purification.

[0101] In some embodiments of this application, this application provides a denitrification method, including the use of a denitrification catalyst to selectively catalytically reduce denitrification with an alcohol as a reducing agent, wherein the denitrification catalyst includes the cobalt-containing zeolite described in any of the foregoing embodiments or the cobalt-containing zeolite prepared according to the method described in any of the foregoing embodiments.

[0102] The cobalt-containing zeolite of this application can purify nitrogen oxides by contacting them with waste gas containing nitrogen oxides. The nitrogen oxides to be purified in this document include nitric oxide, nitrogen dioxide, and nitrous oxide. Purifying nitrogen oxides in this document refers to reacting them on a catalyst to convert them into nitrogen and oxygen. At this time, the nitrogen oxides can react directly, or, for the purpose of improving purification efficiency, they can coexist with a reducing agent in the catalyst. When using a reducing agent, the cobalt-containing zeolite described herein facilitates the purification reaction of nitrogen oxides. The alcohol used as the reducing agent can be any compound with reducing ability at the temperature required for reducing industrial waste gas treatment; preferably, alcohols with 6 or fewer carbon atoms are used as reducing agents, such as one or more of methanol, ethanol, ethylene glycol, propanol, glycerol, isopropanol, and butanol. In a preferred experimental method, the selected alcohol may include methanol and / or ethanol. When the cobalt-containing zeolite of this application is used as a denitrification catalyst, nitrogen oxides contained in various exhaust gases emitted from diesel vehicles, gasoline vehicles, stationary power generation, ships, agricultural machinery, construction machinery, two-wheeled or three-wheeled motor vehicles, various gasoline and diesel engines used in aircraft, boilers, gas turbines, etc. can be purified.

[0103] Example

[0104] The following embodiments are provided to facilitate a better understanding of the implementation schemes of this application, but are not intended to limit them in any way. Unless otherwise specified, the experimental methods used in the following embodiments are conventional methods, and the materials and reagents used are commercially available.

[0105] Solid-state nuclear magnetic resonance (NMR) measurement

[0106] The solid-state NMR instrument used was a Bruker Avance III HD 400WB. 27 The resonance frequency of the Al NMR test was 104.3 MHz, the repetition time was 0.1 s, and the rotation frequency was 10 kHz. 29 The resonance frequency of the Si NMR test was 79.5 MHz, the repetition time was 6 s, and the rotation frequency was 5 kHz.

[0107] X-ray diffraction (XRD) measurement

[0108] The X-ray diffraction instrument used was a Rigaku MiniFlex600, with a Cu Kα light source, a tube voltage of 40 kV, a tube current of 40 mA, a detection angle range of 3-55°, and a scanning speed of 8° / min. The phase structure of the synthesized cobalt-containing zeolite was determined by X-ray diffraction: the ground sample powder was added into a square hole in a glass plate, which was then inserted into the axis of the goniometer. Under Cu Kα light source illumination, the probe rotated at a speed of 2θ / min.

[0109] Methods for evaluating catalyst activity

[0110] The prepared cobalt-containing zeolite was stamped, crushed, and granulated. The granulated cobalt-containing zeolite (2 mL) was then packed into a fixed-bed flow-through reactor at atmospheric pressure. A gas containing the composition shown in Table 2 was circulated over the catalyst bed at a rate of 1000 mL / min (space velocity SV = 30000 / h), while the catalyst bed was simultaneously heated. At different temperatures, the nitrogen oxide removal activity of the catalyst was evaluated based on the outlet NO concentration, N2O concentration, and NO2 concentration using the following formula. (NO...) x Conversion rate) = {(Entry NO)} x Concentration)―(Export NO x Concentration)} / (Inlet NO x concentration)

[0111] Table 2

[0112] Example 1

[0113] 1.48 g of sodium aluminate and 1.12 g of potassium hydroxide were dissolved in 40 g of water, and 6.52 g of silica was added and stirred until homogeneous to obtain an aqueous gel with the following composition: 13SiO2:1Al2O3:1Na2O:1.3K2O:390H2O. Subsequently, 0.14 g of cobalt nitrate hexahydrate was dissolved in 14 g of water and added to the gel. After stirring and maturing at room temperature for 12 hours, the aqueous gel was placed in a temperature- and pressure-resistant container and hydrothermally synthesized at 180°C for 48 hours. The reaction solution was then cooled. The resulting powder was filtered and dried at 100°C for 2 hours to obtain zeolite Al.

[0114] 1.95g of ammonium chloride was dissolved in 21g of water, and then 7g of zeolite A1 was added to form a slurry. The mixture was reacted at 80℃ for 2 hours for ion exchange. The reaction solution was cooled, filtered, and the resulting powder was collected and dried at 100℃ for 2 hours. The resulting powder was calcined in air at 500℃ for 2 hours to obtain zeolite A. Zeolite A... 29The Si solid-state NMR spectrum is shown in Figure 1. Its peak area in the -90ppm to -110ppm chemical shift range accounts for 48% of the peak area in the -90ppm to -125ppm chemical shift range. The XRD results of zeolite A are shown in Figure 2, indicating it is a FER-type zeolite. The Co content of zeolite A is 0.3wt%. The denitrification rate of zeolite A under a high sulfur atmosphere is shown in Table 3.

[0115] Example 2

[0116] 1.48 g of sodium aluminate and 1.12 g of potassium hydroxide were dissolved in 40 g of water, and 6.52 g of silica were added and stirred until homogeneous to obtain an aqueous gel with the following composition: 13SiO2:1Al2O3:1Na2O:1.3K2O:390H2O. Subsequently, 0.24 g of cobalt nitrate hexahydrate was dissolved in 14 g of water and added to the gel. After stirring and maturing at room temperature for 12 hours, the aqueous gel was placed in a temperature- and pressure-resistant container and hydrothermally synthesized at 180°C for 48 hours. The reaction solution was then cooled. The resulting powder was filtered and dried at 100°C for 2 hours to obtain zeolite B1.

[0117] 1.95g of ammonium chloride was dissolved in 21g of water, and then 7g of zeolite B1 was added to form a slurry. The mixture was reacted at 80℃ for 2 hours for ion exchange. The reaction solution was cooled, filtered, and the resulting powder was collected and dried at 100℃ for 2 hours. The resulting powder was calcined in air at 500℃ for 2 hours to obtain zeolite B. Zeolite B... 29 The Si solid-state NMR spectrum is shown in Figure 3. Its peak area in the -90ppm to -110ppm chemical shift range accounts for 48% of the peak area in the -90ppm to -125ppm chemical shift range. The XRD results of zeolite B are shown in Figure 4, indicating it is an FER-type zeolite. The Co content of zeolite B is 0.5wt%. The denitrification rate of zeolite B under a high sulfur atmosphere is shown in Table 3.

[0118] Example 3

[0119] 1.48 g of sodium aluminate and 1.12 g of potassium hydroxide were dissolved in 40 g of water, and 6.52 g of silica were added and stirred until homogeneous to obtain an aqueous gel with the following composition: 13SiO2:1Al2O3:1Na2O:1.3K2O:390H2O. Subsequently, 0.33 g of cobalt nitrate hexahydrate was dissolved in 14 g of water and added to the gel. After stirring and maturing at room temperature for 12 hours, the aqueous gel was placed in a temperature- and pressure-resistant container and hydrothermally synthesized at 180°C for 48 hours. The reaction solution was then cooled. The resulting powder was filtered and dried at 100°C for 2 hours to obtain zeolite C1.

[0120] 1.95g of ammonium chloride was dissolved in 21g of water, and then 7g of zeolite C1 was added to form a slurry. The mixture was reacted at 80℃ for 2 hours for ion exchange. The reaction solution was cooled, filtered, and the resulting powder was collected and dried at 100℃ for 2 hours. The resulting powder was calcined in air at 500℃ for 2 hours to obtain zeolite C. The zeolite C... 29 The Si solid-state NMR spectrum is shown in Figure 5. Its peak area in the -90ppm to -110ppm chemical shift range accounts for 49% of the peak area in the -90ppm to -125ppm chemical shift range. The XRD results of zeolite C are shown in Figure 6, indicating it is a FER-type zeolite. The Co content of zeolite C is 0.7wt%. The denitrification rate of zeolite C under a high sulfur atmosphere is shown in Table 3.

[0121] Example 4

[0122] 1.1663 g of sodium aluminate and 1.12 g of potassium hydroxide were dissolved in 40 g of water, and 6.52 g of silica was added and stirred until homogeneous to obtain an aqueous gel with the following composition: 16.5 SiO2:1 Al2O3:1 Na2O:1.3 K2O:390 H2O. Subsequently, 0.24 g of cobalt nitrate hexahydrate was dissolved in 14 g of water and added to the gel. After stirring and maturing at room temperature for 12 hours, the aqueous gel was placed in a temperature- and pressure-resistant container and hydrothermally synthesized at 180 °C for 48 hours. The reaction solution was then cooled. The resulting powder was filtered and dried at 100 °C for 2 hours to obtain zeolite D1.

[0123] 1.95g of ammonium chloride was dissolved in 21g of water, and then 7g of zeolite D1 was added to form a slurry. The mixture was reacted at 80℃ for 2 hours for ion exchange. The reaction solution was cooled, filtered, and the resulting powder was dried at 100℃ for 2 hours. The resulting powder was calcined in air at 500℃ for 2 hours to obtain zeolite D. Zeolite D... 29 The Si solid-state NMR spectrum is shown in Figure 7. Its peak area in the -90ppm to -110ppm chemical shift range accounts for 40% of the peak area in the -90ppm to -125ppm chemical shift range. The XRD results of zeolite D are shown in Figure 8, indicating it is an FER-type zeolite. The Co content of zeolite D is 0.4wt%. The denitrification rate of zeolite D in methanol-SCR under a high sulfur atmosphere is shown in Table 3.

[0124] Example 5

[0125] 1.48 g of sodium aluminate and 1.12 g of potassium hydroxide were dissolved in 40 g of water, and 6.52 g of silica were added and stirred until homogeneous to obtain an aqueous gel with the following composition: 13SiO2:1Al2O3:1Na2O:1.3K2O:390H2O. Subsequently, 0.04 g of cobalt nitrate hexahydrate was dissolved in 14 g of water and added to the gel. After stirring and maturing at room temperature for 12 hours, the aqueous gel was placed in a temperature- and pressure-resistant container and hydrothermally synthesized at 180°C for 48 hours. The reaction solution was then cooled. The resulting powder was filtered and dried at 100°C for 2 hours to obtain zeolite E1.

[0126] 1.95g of ammonium chloride was dissolved in 21g of water, and then 7g of zeolite E1 was added to form a slurry. The mixture was reacted at 80℃ for 2 hours for ion exchange. The reaction solution was cooled, filtered, and the resulting powder was collected and dried at 100℃ for 2 hours. The resulting powder was calcined in air at 500℃ for 2 hours to obtain zeolite E. Zeolite E... 29 The Si solid-state NMR spectrum is shown in Figure 9. Its peak area in the -90ppm to -110ppm chemical shift range accounts for 58% of the peak area in the -90ppm to -125ppm chemical shift range. The XRD results of zeolite E are shown in Figure 10, indicating it is an FER-type zeolite. The Co content of zeolite E is 0.1wt%. The denitrification rate of zeolite E under a high sulfur atmosphere is shown in Table 3.

[0127] Example 6

[0128] 1.48 g of sodium aluminate and 1.12 g of potassium hydroxide were dissolved in 40 g of water, and 6.52 g of silica were added and stirred until homogeneous to obtain an aqueous gel with the following composition: 13SiO2:1Al2O3:1Na2O:1.3K2O:390H2O. Subsequently, 0.4 g of cobalt nitrate hexahydrate was dissolved in 14 g of water and added to the gel. After stirring and maturing at room temperature for 12 hours, the aqueous gel was placed in a temperature- and pressure-resistant container and hydrothermally synthesized at 180°C for 48 hours. The reaction solution was then cooled. The resulting powder was filtered and dried at 100°C for 2 hours to obtain zeolite F1.

[0129] 1.95g of ammonium chloride was dissolved in 21g of water, and then 7g of zeolite F1 was added to form a slurry. The mixture was reacted at 80℃ for 2 hours for ion exchange. The reaction solution was cooled, filtered, and the resulting powder was dried at 100℃ for 2 hours. The resulting powder was calcined in air at 500℃ for 2 hours to obtain zeolite F. Zeolite F... 29The Si solid-state NMR spectrum is shown in Figure 11. Its peak area in the -90ppm to -110ppm chemical shift range accounts for 51% of the peak area in the -90ppm to -125ppm chemical shift range. The XRD results of zeolite F are shown in Figure 12, indicating it is an FER-type zeolite. The Co content of zeolite F is 1 wt%. The denitrification rate of zeolite F under a high sulfur atmosphere is shown in Table 3.

[0130] Example 7

[0131] 1.48 g of sodium aluminate and 1.12 g of potassium hydroxide were dissolved in 54 g of water, and 6.52 g of silica was added and stirred until homogeneous to obtain an aqueous gel with the following composition: 13SiO2:1Al2O3:1Na2O:1.3K2O:390H2O. After stirring and maturing at room temperature for 12 hours, the aqueous gel was placed in a temperature- and pressure-resistant container and hydrothermally synthesized at 180°C for 48 hours. The reaction solution was then cooled. The obtained powder was filtered and dried at 100°C for 2 hours to obtain zeolite G1.

[0132] 1.95g of ammonium chloride was dissolved in 21g of water, and then 7g of zeolite G1 was added to form a slurry. The mixture was reacted at 80℃ for 2 hours for ion exchange. The reaction solution was cooled, filtered, and the resulting powder was dried at 100℃ for 2 hours to obtain zeolite G2. 0.015g of cobalt nitrate hexahydrate was dissolved in 12g of water, and then 3g of zeolite G2 was added to form a slurry. The mixture was reacted at 80℃ for 2 hours for ion exchange. The reaction solution was cooled, filtered, and the resulting powder was dried at 100℃ for 2 hours. The resulting powder was calcined in air at 500℃ for 4 hours to obtain zeolite G3. 1g of zeolite G3 was physically ground and mixed with 0.04g of cobalt tetroxide powder to obtain zeolite G. The zeolite G... 29 The Si solid-state NMR spectrum is shown in Figure 13. Its peak area in the -90ppm to -110ppm chemical shift range accounts for 54% of the peak area in the -90ppm to -125ppm chemical shift range. The XRD results of zeolite G are shown in Figure 14, indicating it is an FER-type zeolite. The Co content of zeolite G is 3wt%. The denitrification rate of zeolite G under a high sulfur atmosphere is shown in Table 3.

[0133] Example 8

[0134] 1.48 g of sodium aluminate and 1.12 g of potassium hydroxide were dissolved in 54 g of water, and 6.52 g of silica was added and stirred until homogeneous to obtain an aqueous gel with the following composition: 13SiO2:1Al2O3:1Na2O:1.3K2O:390H2O. After stirring and maturing at room temperature for 12 hours, the aqueous gel was placed in a temperature- and pressure-resistant container and hydrothermally synthesized at 180°C for 48 hours. The reaction solution was then cooled. The obtained powder was collected by filtration and dried at 100°C for 2 hours to obtain zeolite H1.

[0135] 1.95g of ammonium chloride was dissolved in 21g of water, and then 7g of zeolite H1 was added to form a slurry. The mixture was reacted at 80℃ for 2 hours for ion exchange. The reaction solution was cooled, filtered, and the resulting powder was dried at 100℃ for 2 hours to obtain zeolite H2. 0.015g of cobalt nitrate hexahydrate was dissolved in 12g of water, and then 3g of zeolite H2 was added to form a slurry. The mixture was reacted at 80℃ for 2 hours for ion exchange. The reaction solution was cooled, filtered, and the resulting powder was dried at 100℃ for 2 hours. The resulting powder was calcined in air at 500℃ for 4 hours to obtain zeolite H3. 1g of zeolite H3 was physically ground and mixed with 0.07g of cobalt tetroxide powder to obtain zeolite H. The composition of zeolite H... 29 The Si solid-state NMR spectrum is shown in Figure 15. Its peak area in the -90ppm to -110ppm chemical shift range accounts for 53% of the peak area in the -90ppm to -125ppm chemical shift range. The XRD results of zeolite H are shown in Figure 16, indicating it is an FER-type zeolite. The Co content of zeolite H is 5wt%. The denitrification rate of zeolite H under a high sulfur atmosphere is shown in Table 3.

[0136] Example 9

[0137] 1.48 g of sodium aluminate and 1.12 g of potassium hydroxide were dissolved in 54 g of water, and 6.52 g of silica was added and stirred until homogeneous to obtain an aqueous gel with the following composition: 13SiO2:1Al2O3:1Na2O:1.3K2O:390H2O. After stirring and maturing at room temperature for 12 hours, the aqueous gel was placed in a temperature- and pressure-resistant container and hydrothermally synthesized at 180°C for 48 hours. The reaction solution was then cooled. The obtained powder was filtered and dried at 100°C for 2 hours to obtain zeolite I1.

[0138] 1.95g of ammonium chloride was dissolved in 21g of water, and then 7g of zeolite I1 was added to form a slurry. The mixture was reacted at 80℃ for 2 hours for ion exchange. The reaction solution was cooled, filtered, and the resulting powder was dried at 100℃ for 2 hours to obtain zeolite I2. 0.015g of cobalt nitrate hexahydrate was dissolved in 12g of water, and then 3g of zeolite I2 was added to form a slurry. The mixture was reacted at 80℃ for 2 hours for ion exchange. The reaction solution was cooled, filtered, and the resulting powder was dried at 100℃ for 2 hours. The resulting powder was calcined in air at 500℃ for 4 hours to obtain zeolite I3. 1g of zeolite I3 was physically ground and mixed with 0.1g of cobalt tetroxide powder to obtain zeolite I. Zeolite I... 29 The Si solid-state NMR spectrum is shown in Figure 17. Its peak area in the -90ppm to -110ppm chemical shift range accounts for 51% of the peak area in the -90ppm to -125ppm chemical shift range. The XRD results of zeolite I are shown in Figure 18, indicating it is a FER-type zeolite. The Co content of zeolite I is 7wt%. The denitrification rate of zeolite I under a high sulfur atmosphere is shown in Table 3.

[0139] Example 10

[0140] 1.48 g of sodium aluminate and 1.12 g of potassium hydroxide were dissolved in 54 g of water, and 6.52 g of silica was added and stirred until homogeneous to obtain an aqueous gel with the following composition: 13SiO2:1Al2O3:1Na2O:1.3K2O:390H2O. After stirring and maturing at room temperature for 12 hours, the aqueous gel was placed in a temperature- and pressure-resistant container and hydrothermally synthesized at 180°C for 48 hours. The reaction solution was then cooled. The obtained powder was filtered and dried at 100°C for 2 hours to obtain zeolite J1.

[0141] 1.95g of ammonium chloride was dissolved in 21g of water, and then 7g of zeolite J1 was added to form a slurry. The mixture was reacted at 80℃ for 2 hours for ion exchange. The reaction solution was cooled, filtered, and the resulting powder was dried at 100℃ for 2 hours to obtain zeolite J2. 0.015g of cobalt nitrate hexahydrate was dissolved in 12g of water, and then 3g of zeolite J2 was added to form a slurry. The mixture was reacted at 80℃ for 2 hours for ion exchange. The reaction solution was cooled, filtered, and the resulting powder was dried at 100℃ for 2 hours. The resulting powder was calcined in air at 500℃ for 4 hours to obtain zeolite J3. 1g of zeolite J3 was physically ground and mixed with 0.11g of cobalt tetroxide powder to obtain zeolite J. The composition of zeolite J... 29 The Si solid-state NMR spectrum is shown in Figure 19. Its peak area in the -90ppm to -110ppm chemical shift range accounts for 51% of the peak area in the -90ppm to -125ppm chemical shift range. The XRD results of zeolite J are shown in Figure 20, indicating it is an FER-type zeolite. The Co content of zeolite J is 8 wt%. The denitrification rate of zeolite J under a high sulfur atmosphere is shown in Table 3.

[0142] Comparative Example 1

[0143] 1.1663 g of sodium aluminate and 1.12 g of potassium hydroxide were dissolved in 40 g of water, and 6.52 g of silica were added and stirred until homogeneous to obtain an aqueous gel with the following composition: 16.5 SiO2:1 Al2O3:1 Na2O:1.3 K2O:390 H2O. Subsequently, 0.14 g of cobalt nitrate hexahydrate was dissolved in 14 g of water and added to the gel. After stirring and maturing at room temperature for 12 hours, the aqueous gel was placed in a temperature- and pressure-resistant container and hydrothermally synthesized at 180°C for 48 hours. The reaction solution was then cooled. The resulting powder was filtered and dried at 100°C for 2 hours to obtain zeolite K1.

[0144] 1.95 g of ammonium chloride was dissolved in 21 g of water, and then 7 g of zeolite K1 was added to form a slurry. The mixture was reacted at 80 °C for 2 hours for ion exchange. The reaction solution was cooled, filtered, and the resulting powder was dried at 100 °C for 2 hours. The powder was then mixed with 140 mL of 0.1 mol / L barium nitrate solution and stirred at room temperature for 8 hours. The resulting powder was filtered and dried at 100 °C for 2 hours. Finally, the obtained powder was calcined in air at 500 °C for 2 hours to obtain zeolite K. (The text abruptly ends here, likely due to an incomplete sentence or missing information.) 29 The Si solid-state NMR spectrum is shown in Figure 21. Its peak area in the -90ppm to -110ppm chemical shift range accounts for 48% of the peak area in the -90ppm to -125ppm chemical shift range. The XRD results of zeolite K are shown in Figure 22, indicating it is an FER-type zeolite. Zeolite K has a Co content of 0.3wt% and a barium content of 1.1wt%. The denitrification rate of zeolite K under a high sulfur atmosphere is shown in Table 3.

[0145] Comparative Example 2

[0146] TOSOH Corporation of Japan calcined NH4-type FER zeolite (HSZ-720NHA, SiO2 / Al2O3 molar ratio 18) in air at 500°C for 2 hours to obtain zeolite L1. 0.015 g of cobalt nitrate hexahydrate was dissolved in 12 g of water, and then 3 g of zeolite L1 was added to form a slurry. The slurry was reacted at 80°C for 2 hours for ion exchange. The reaction solution was cooled, filtered, and the resulting powder was dried at 100°C for 2 hours. The resulting powder was then calcined in air at 500°C for 4 hours to obtain zeolite L. Zeolite L... 29 The Si solid-state NMR spectrum is shown in Figure 23. Its peak area in the -90ppm to -110ppm chemical shift range accounts for 33% of the peak area in the -90ppm to -125ppm chemical shift range. The XRD results of zeolite L are shown in Figure 24, indicating it is an FER-type zeolite. The Co content of zeolite L is 0.1wt%. The denitrification rate of zeolite L under a high sulfur atmosphere is shown in Table 3.

[0147] Comparative Example 3

[0148] FER-type zeolite M was obtained according to the preparation method in Example 5 of patent document WO2013146729A1. Zeolite M... 29 The Si solid-state NMR spectrum is shown in Figure 25. Its peak area in the -110 ppm to -90 ppm chemical shift range accounts for 29% of the peak area in the -125 ppm to -90 ppm chemical shift range. The XRD results of zeolite M are shown in Figure 26, indicating it is an FER-type zeolite. The Co content of zeolite M is 0.1 wt%. The denitrification rate of zeolite M under a high sulfur atmosphere is shown in Table 3.

[0149] Comparative Example 4

[0150] 1.48 g of sodium aluminate and 1.12 g of potassium hydroxide were dissolved in 40 g of water, and 6.52 g of silica was added and stirred until homogeneous to obtain an aqueous gel with the following composition: 13SiO2:1Al2O3:1Na2O:1.3K2O:390H2O. Subsequently, 0.24 g of cobalt nitrate hexahydrate was dissolved in 14 g of water and added to the gel. After stirring and maturing at room temperature for 12 hours, the aqueous gel was placed in a temperature- and pressure-resistant container and hydrothermally synthesized at 180°C for 48 hours. The reaction solution was then cooled. The resulting powder was filtered and dried at 100°C for 2 hours to obtain zeolite N1.

[0151] 1.95 g of ammonium chloride was dissolved in 21 g of water, and then 7 g of zeolite N1 was added to form a slurry. The mixture was reacted at 80 °C for 2 hours for ion exchange. The reaction solution was cooled, filtered, and the resulting powder was dried at 100 °C for 2 hours. The powder was then mixed with 28 mL of a 4% vanadium oxysulfate solution and stirred at room temperature for 8 hours. The resulting powder was filtered and dried at 100 °C for 2 hours. Finally, the obtained powder was calcined in air at 500 °C for 2 hours to obtain zeolite N. (The text abruptly ends here, likely due to an incomplete sentence or missing information.) 29 The Si solid-state NMR spectrum is shown in Figure 27. Its peak area in the -90ppm to -110ppm chemical shift range accounts for 43% of the peak area in the -90ppm to -125ppm chemical shift range. The XRD results of zeolite N are shown in Figure 28, indicating it is an FER-type zeolite. The V content of zeolite N is 0.1wt%, and the Co content is 0.5wt%. The denitrification rate of zeolite N under a high sulfur atmosphere is shown in Table 3.

[0152] Comparative Example 5

[0153] Zeolite O1 was obtained by calcining NH4-type FER-type zeolite (HSZ-720NHA, SiO2 / Al2O3 molar ratio 18) in air at 500°C for 2 hours from TOSOH Corporation of Japan. An ammonium metavanadate aqueous solution was prepared by dissolving 0.0345 g of ammonium metavanadate in 10.8 g of water under a 60°C water bath. Then, 3 g of the calcined zeolite O1 was added and stirred until homogeneous. The solution was then removed by rotary evaporation at 60°C. The resulting powder was dried in a vacuum drying oven at 100°C for 12 hours, ground until homogeneous, and then calcined in a muffle furnace at 500°C for 4 hours to obtain zeolite O. (The text abruptly ends here, likely due to an incomplete sentence or missing information.) 29 The Si solid-state NMR spectrum is shown in Figure 29. Its peak area in the -90ppm to -110ppm chemical shift range accounts for 31% of the peak area in the -90ppm to -125ppm chemical shift range. The XRD results of zeolite O are shown in Figure 30, indicating it is a FER-type zeolite. The V content of zeolite O is 0.5wt%. The denitrification rate of zeolite O under a high sulfur atmosphere is shown in Table 3.

[0154] Comparative Example 6

[0155] FER-type zeolite P was obtained according to the preparation method in Example 2 of patent document WO2021 / 114208A1. Zeolite P... 29 The Si solid-state NMR spectrum is shown in Figure 31. Its peak area in the -110ppm to -90ppm chemical shift range accounts for 36% of the peak area in the -125ppm to -90ppm chemical shift range. The denitrification rate of zeolite P in methanol-SCR under a high sulfur atmosphere is shown in Table 3.

[0156] Table 3

[0157] As shown in Table 3, the cobalt-containing zeolite used in Examples 1-10 was... 29 When analyzed by Si solid-state NMR spectroscopy, the peak area in the -110ppm to -90ppm chemical shift range accounted for more than 35% and less than 85% of the peak area in the -125ppm to -90ppm chemical shift range. Furthermore, the cobalt-containing zeolite did not support vanadium or other metals such as barium, but only cobalt, with a cobalt mass percentage higher than or greater than 0.1%. Compared to the zeolite of Comparative Example 1, which simultaneously supported cobalt and barium, and the cobalt-containing zeolite prepared by ion exchange in Comparative Example 2, the cobalt-containing zeolite in the published patent of Comparative Example 3, the zeolite of Comparative Example 4 containing both cobalt and vanadium, the zeolite of Comparative Example 5 containing only vanadium and no cobalt, and the zeolite of Comparative Example 6 containing no cobalt, the cobalt-containing zeolites of Examples 1-10 all exhibited superior denitrification activity under conditions of low temperature (275°C) and sulfur content of 1200ppm. This demonstrates that when using the cobalt-containing zeolite of this application as a denitrification catalyst and alcohol as a reducing agent for selective catalytic reduction denitrification, the problem of severe deactivation in the temperature range below 300°C can be solved, thereby addressing the issue of low denitrification efficiency in industrial flue gas with high sulfur content and low emission temperature.

[0158] The above description is merely a specific embodiment of the invention covered by this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A cobalt-containing zeolite, characterized in that, It contains at least silicon, aluminum, and oxygen as framework atoms, with a molar ratio of silicon to aluminum atoms of 2 to 100:

1. Based on the total mass of the cobalt-containing zeolite, the mass percentage of cobalt is greater than or equal to 0.1%. The cobalt-containing zeolite was treated with 29 When analyzing the nuclear magnetic resonance spectrum of Si solid, the peak area in the chemical shift range of -110 ppm to -90 ppm accounts for 35%-85% of the peak area in the chemical shift range of -125 ppm to -90 ppm.

2. The cobalt-containing zeolite according to claim 1, characterized in that, The cobalt-containing zeolite is a cobalt-containing FER-type zeolite.

3. The cobalt-containing zeolite according to claim 1 or 2, characterized in that, Based on the total mass of the cobalt-containing zeolite, the mass percentage of cobalt is 0.1%-7%, preferably 0.1%-5%.

4. A method for preparing the cobalt-containing zeolite according to any one of claims 1-3, characterized in that, include: A silicon source, an aluminum source, a cobalt source, and an inorganic alkali are mixed and heated to obtain crystalline zeolite; The alkali metal ions in the zeolite are removed to obtain cobalt-containing zeolite.

5. The method according to claim 4, characterized in that, Before mixing and heating the silicon source, the aluminum source, the cobalt source and the inorganic base, an organic template agent is added to obtain crystalline zeolite.

6. A method for preparing the cobalt-containing zeolite according to any one of claims 1-3, characterized in that, include: A silicon source, an aluminum source, and an inorganic alkali are mixed and heated to obtain crystalline zeolite; Alkali metal ions in zeolite are removed by ion exchange, and then cobalt ions are introduced into the zeolite after the alkali metal ions have been removed by ion exchange. By mixing cobalt ions-introduced zeolite with cobalt oxide, cobalt-containing zeolite is obtained; Optionally, an organic template agent is added before heating the silicon source, the aluminum source, and the inorganic base to obtain crystalline zeolite.

7. The use of the cobalt-containing zeolite according to any one of claims 1-3 or the cobalt-containing zeolite prepared by any one of claims 4-6 as a denitrification catalyst in selective catalytic reduction denitrification using alcohol as a reducing agent; Optionally, the alcohol contains 1-6 carbon atoms.

8. A catalytic reactor for purifying nitrogen oxides, characterized in that, The catalytic reactor includes a denitrification catalyst, which includes cobalt-containing zeolite according to any one of claims 1-3 or cobalt-containing zeolite prepared by any one of claims 4-6.

9. A nitrogen oxide purification system, characterized in that, The system is equipped with the catalytic reactor for nitrogen oxide purification as described in claim 8.

10. A denitrification method, characterized in that, This includes using a denitrification catalyst to selectively catalytically reduce denitrification with an alcohol as a reducing agent, wherein the denitrification catalyst comprises any one of the cobalt-containing zeolites according to claims 1-3 or cobalt-containing zeolites prepared by the method according to any one of claims 4-6.

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