Vanadium-containing FER zeolite and use thereof

Abstract

Provided is a vanadium-containing FER zeolite, which at least comprises silicon, aluminum and oxygen as skeleton atoms, wherein the molar ratio of the silicon atom to the aluminum atom is 2-30 : 1; and the mass percentage content of vanadium is 0.1-3% based on the mass of the zeolite. When the zeolite is analyzed by 29Si solid-state nuclear magnetic resonance spectrum, the peak area in the chemical shift range of -110 - -90 ppm accounts for more than 23% and less than 85% of the peak area in the chemical shift range of -125 - -90 ppm. Further provided are a method for preparing the vanadium-containing FER zeolite and the use thereof as a catalyst in selective catalytic reduction and denitration with an alcohol as reducing agent.

Description

Vanadium-containing FER zeolite and its application

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This disclosure claims priority to and the benefit of Chinese Patent Application No. 202311563299.7, which is incorporated herein by reference in its entirety. Technical Field

[0003] The present disclosure relates to the field of denitration catalysts, and more specifically, to a vanadium-containing FER-type zeolite denitration catalyst, a preparation method thereof, and applications thereof. Background Art

[0004] Nitrogen oxides (NO x ) is highly irritating and corrosive, and can cause damage to human health. In addition, nitrogen oxides in the atmosphere are also prone to interact with other harmful compounds to generate harmful substances such as sulfates and nitrates, which are one of the main culprits of atmospheric haze. Selective catalytic reduction technology (SCR) is currently the main flue gas denitrification technology. It uses a reducing agent to selectively react with nitrogen oxides in the flue gas under the action of a catalyst to generate nitrogen and water, thereby removing nitrogen oxides. However, when treating industrial waste gas generated by high-sulfur fuel industries such as coal and heavy oil, such fuels will produce a certain amount of sulfur oxides in the industrial process. When using ammonia as a reducing agent in a flue gas denitrification process, sulfur oxides often react with the reducing agent ammonia to form ammonium sulfate by-products. Since ammonium sulfate is corrosive and sticky, it is easy to adhere to the surface of objects, which can cause problems such as catalyst deactivation and equipment failure.

[0005] Using lower alcohol compounds as reducing agents does not react with sulfur oxides to form deposits. Liquid lower alcohols as reducing agents (alcohol-SCR) are safer to store than aqueous ammonia and avoid the problem of urea precipitation at low temperatures, which can easily lead to pipeline blockage. For example, JP2022161381A discloses the use of Ag and Bi as active metal-loaded MFI or FER zeolites for denitrification using methanol as a reducing agent. Although the catalyst achieves good catalytic activity at 300°C, carbon deposition is prone to occur during the reaction, resulting in reduced catalytic activity. Furthermore, the document states that vanadium is not suitable as a metal active component for denitrification reactions using methanol as a reducing agent.

[0006] However, the supported denitrification catalysts in the art using lower alcohols as reducing agents generally have high reaction temperatures, for example, requiring a catalytic reaction temperature of more than 300°C, or have low denitrification efficiency, unstable structure, or deactivation or reduced activity due to coking or carbon deposition of organic matter during use. Summary of the Invention

[0007] The inventors of the present disclosure have conducted in-depth research on the technical problems existing in the field and found that one or more of the above technical problems can be solved by the following technical solutions.

[0008] According to a first aspect of the present disclosure, there is provided a vanadium-containing FER zeolite, the zeolite comprising at least silicon, aluminum, and oxygen as framework atoms, wherein the molar ratio of silicon atoms to aluminum atoms is 2 to 30:1, wherein the mass percentage of vanadium is 0.1 to 3% based on the mass of the zeolite, and the zeolite is treated with 29 When Si solid-state nuclear magnetic resonance spectroscopy is analyzed, the peak area in the chemical shift range of -110 to -90 ppm accounts for 23% or more and 85% or less of the peak area in the chemical shift range of -125 to -90 ppm.

[0009] In some embodiments, the zeolite is treated with 27 When A1 is analyzed by solid-state nuclear magnetic resonance spectrum, the peak area in the chemical shift range of -50 to 40 ppm accounts for less than 60% of the peak area in the chemical shift range of -50 to 150 ppm.

[0010] In some embodiments, the vanadium is within the framework of the zeolite and / or outside the framework of the zeolite, for example, outside the framework of the zeolite.

[0011] In some embodiments, cations are present outside the framework of the zeolite and include hydrogen or ammonium ions.

[0012] According to a second aspect of the present disclosure, a method for producing a vanadium-containing FER-type zeolite is provided, the method comprising: removing alkali metal ions from an FER-type zeolite raw material by an ion exchange method to obtain a treated zeolite, and then loading vanadium on the treated zeolite to obtain the vanadium-containing FER-type zeolite; or loading vanadium on an H-type or ammonium-type FER-type zeolite to obtain the vanadium-containing FER-type zeolite.

[0013] In some embodiments, the vanadium is provided by a vanadium source selected from ammonium metavanadate, sodium metavanadate, potassium metavanadate, sodium orthovanadate, vanadyl sulfate, vanadyl oxalate, vanadium tetrachloride, vanadium oxytrichloride, or any combination thereof. Preferably, the vanadium source is in the form of a solution, more preferably, the vanadium source is in the form of an aqueous solution.

[0014] Optionally, the mass ratio of vanadium source (calculated as elemental vanadium): H-type or ammonium-type FER zeolite is 0.0005-0.05 g V: 1 g H-type FER zeolite.

[0015] According to a third aspect of the present disclosure, a catalytic reactor for purifying nitrogen oxides is provided, wherein the catalytic reactor comprises the vanadium-containing FER zeolite described in the first aspect or the vanadium-containing FER zeolite prepared by the method described in the second aspect as a denitration catalyst.

[0016] According to a fourth aspect of the present disclosure, a nitrogen oxide purification system is provided, wherein the system is provided with the catalytic reactor for nitrogen oxide purification according to the third aspect.

[0017] According to a fifth aspect of the present disclosure, a denitration method is provided, comprising using the vanadium-containing FER zeolite described in the first aspect or the vanadium-containing FER zeolite prepared by the method described in the second aspect as a denitration catalyst, and using an alcohol containing 6 or less carbon atoms as a reducing agent to perform selective catalytic reduction denitration.

[0018] According to a sixth aspect of the present disclosure, there is provided a method for improving the low-temperature denitration performance and / or durability of an FER-type zeolite, the method comprising loading vanadium on the FER-type zeolite.

[0019] This disclosure addresses at least the issues of low catalyst activity and insufficient high-temperature hydrothermal stability in the temperature range below 300°C when using lower alcohols such as methanol as reducing agents for selective catalytic reduction denitration. This disclosure provides a lower alcohol-SCR denitration catalyst with high catalytic activity and high hydrothermal stability in the temperature range below 300°C, thereby addressing the denitration treatment of industrial flue gas at relatively low emission temperatures. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The embodiments illustrated herein are further described below with reference to the accompanying drawings, but the accompanying drawings are only for allowing those skilled in the art to better understand the present invention and are not intended to limit the scope of the present invention.

[0021] FIG1 is an XRD pattern of zeolite A prepared according to one embodiment of the present disclosure;

[0022] FIG. 2 is a diagram of zeolite A prepared according to one embodiment of the present disclosure. 29 Si solid-state NMR spectroscopy;

[0023] FIG3 is a diagram of zeolite A prepared according to one embodiment of the present disclosure. 29 Al solid-state NMR spectroscopy;

[0024] FIG4 is an XRD pattern of zeolite B prepared according to one embodiment of the present disclosure;

[0025] FIG. 5 is a diagram of zeolite B prepared according to one embodiment of the present disclosure. 29 Si solid-state NMR spectroscopy;

[0026] FIG. 6 is a diagram of zeolite B prepared according to one embodiment of the present disclosure. 27 Al solid-state NMR spectroscopy;

[0027] FIG7 is an XRD pattern of zeolite C prepared according to one embodiment of the present disclosure;

[0028] FIG8 is a diagram of zeolite C prepared according to one embodiment of the present disclosure. 29 Si solid-state NMR spectroscopy;

[0029] FIG. 9 is a diagram of zeolite C prepared according to one embodiment of the present disclosure. 27 Al solid-state NMR spectroscopy;

[0030] FIG10 is an XRD pattern of zeolite D prepared according to one embodiment of the present disclosure;

[0031] FIG. 11 is a diagram of zeolite D prepared according to one embodiment of the present disclosure. 29 Si solid-state NMR spectroscopy;

[0032] FIG. 12 is a diagram of zeolite D prepared according to one embodiment of the present disclosure. 27 Al solid-state NMR spectroscopy;

[0033] FIG13 is an XRD pattern of zeolite E prepared according to one embodiment of the present disclosure;

[0034] FIG. 14 is a diagram of zeolite E prepared according to one embodiment of the present disclosure. 29 Si solid-state NMR spectroscopy;

[0035] FIG. 15 is a diagram of zeolite E prepared according to one embodiment of the present disclosure. 27 Al solid-state NMR spectroscopy;

[0036] FIG16 is an XRD pattern of zeolite F prepared according to one embodiment of the present disclosure;

[0037] FIG. 17 is a diagram of zeolite F prepared according to one embodiment of the present disclosure. 29 Si solid-state NMR spectroscopy;

[0038] FIG. 18 is a diagram of zeolite F prepared according to one embodiment of the present disclosure. 27 Al solid-state NMR spectroscopy;

[0039] FIG19 is an XRD pattern of zeolite G prepared according to one embodiment of the present disclosure;

[0040] FIG. 20 is a diagram of zeolite G prepared according to one embodiment of the present disclosure. 29 Si solid-state NMR spectroscopy;

[0041] FIG. 21 is a diagram of zeolite G prepared according to one embodiment of the present disclosure. 27 Al solid-state NMR spectroscopy;

[0042] FIG22 is an XRD pattern of zeolite H prepared according to one embodiment of the present disclosure;

[0043] FIG. 23 is a diagram of zeolite H prepared according to one embodiment of the present disclosure. 29 Si solid-state NMR spectroscopy;

[0044] FIG. 24 is a diagram of zeolite H prepared according to one embodiment of the present disclosure. 27 Al solid-state NMR spectroscopy;

[0045] FIG25 is an XRD pattern of zeolite 1 prepared according to one embodiment of the present disclosure;

[0046] FIG. 26 is a diagram of zeolite 1 prepared according to one embodiment of the present disclosure. 29 Si solid-state NMR spectroscopy;

[0047] FIG. 27 is a diagram of zeolite 1 prepared according to one embodiment of the present disclosure. 27 Al solid-state NMR spectroscopy;

[0048] FIG28 is an XRD pattern of zeolite K prepared according to a comparative example of the present disclosure;

[0049] FIG. 29 is a graph showing a zeolite K prepared according to a comparative example of the present disclosure. 29 Si solid-state NMR spectroscopy;

[0050] FIG30 is a graph showing a zeolite K prepared according to a comparative example of the present disclosure. 27 Al solid-state NMR spectroscopy;

[0051] FIG31 is an XRD pattern of zeolite L prepared according to a comparative example of the present disclosure;

[0052] FIG32 is a diagram of zeolite L prepared according to a comparative example of the present disclosure. 29 Si solid-state NMR spectroscopy;

[0053] FIG. 33 is a diagram of zeolite L prepared according to one embodiment of the present disclosure. 27 Al solid-state NMR spectroscopy;

[0054] FIG34 is an XRD pattern of zeolite M prepared according to a comparative example of the present disclosure.

[0055] FIG35 is a diagram of zeolite M prepared according to a comparative example of the present disclosure. 29 Si solid-state NMR spectroscopy;

[0056] FIG36 is a diagram of zeolite M prepared according to a comparative example of the present disclosure. 27 Al solid-state NMR spectroscopy;

[0057] 37 is an XRD pattern of zeolite N prepared according to a comparative example of the present disclosure.

[0058] FIG38 is a graph showing a zeolite N prepared according to a comparative example of the present disclosure. 29 Si solid-state NMR spectroscopy;

[0059] FIG39 is a graph showing a zeolite N prepared according to a comparative example of the present disclosure. 27 Al solid-state NMR spectroscopy;

[0060] FIG40 is a graph showing a zeolite O prepared according to a comparative example of the present disclosure. 29 Si solid-state NMR spectroscopy;

[0061] FIG41 is a diagram of zeolite O prepared according to a comparative example of the present disclosure. 27 Al solid-state NMR spectrum.

[0062] Figure 42 is an illustration 29 Schematic diagram of the relationship between the chemical shift of Si and the state of Si in Si solid-state NMR spectrum. DETAILED DESCRIPTION

[0063] Hereinafter, the inventive concept of the present disclosure will be further described based on specific examples. However, the specific embodiments listed are for illustrative purposes only and are not intended to limit the scope of the present disclosure. Those skilled in the art will recognize that the specific features in any of the following embodiments can be used in any other embodiment as long as it does not deviate from the inventive concept described herein.

[0064] Vanadium-containing FER zeolite

[0065] The zeolites mentioned herein are all zeolites specified by the International Zeolite Association (hereinafter referred to as IZA), such as FER zeolite, MFI zeolite, FAU zeolite, etc. Zeolite is generally a regular mesh structure formed by the oxygen atoms at each vertex of the skeleton atom tetrahedron (such as SiO4 tetrahedron, AlO4 tetrahedron or PO4 tetrahedron) being connected by sharing, and the element atoms other than oxygen are usually referred to as non-oxygen atoms or T atoms. For FER zeolite, its structure can be determined by X-ray diffraction (XRD), and it is necessary to detect at least the interplanar spacing shown in Table 1 below. That is, if the zeolite has the interplanar spacing shown in Table 1 below, the zeolite may be an FER-type zeolite or an FER-type molecular sieve.

[0066] Table 1

[0067] The vanadium-containing FER zeolite provided herein contains at least oxygen, aluminum, and silicon as framework atoms, and a portion of the framework atoms may be substituted with one or more elements other than the aforementioned three elements. In one embodiment, the molar ratio of silicon atoms to aluminum atoms is 2 to 30:1, for example, 2:1, 5:1, 8:1, 10:1, 12:1, 15:1, 18:1, 20:1, or 25:1.

[0068] The vanadium-containing FER zeolite described herein is 29 When Si solid-state nuclear magnetic resonance spectrum is analyzed, its peak area in the chemical shift range of -110 to -90 ppm accounts for more than 23% and less than 85% of the peak area in the chemical shift range of -125 to -90 ppm, such as more than 25%, more than 28%, more than 30%, more than 35%, more than 40% or more than 45%, and less than 80%, less than 75%, less than 70%, less than 65% or less than 60%. After research, it was found that the zeolite with the above characteristics has high alcohol-SCR denitrification catalytic activity. It is generally believed that 29 The characteristic peaks in the -110 to -90 ppm chemical shift range in Si solid-state NMR spectra reflect information about framework silicon connected to framework Al. A higher percentage of the absorption peak area in this range indicates a greater number of characteristic acid active sites in the zeolite, leading to higher alcohol-SCR catalytic activity.

[0069] For FER zeolite, 29 The chemical shift of Si in the Si solid-state NMR spectrum reflects the local state of silicon atoms, that is, it can reflect the chemical form of Si in FER-type zeolite. Specifically, the applicant provides a schematic diagram to illustrate 29 The relationship between the chemical shift of Si and the state of Si in the Si solid-state NMR spectrum. As shown in Figure 42, the chemical environment of Si is represented by Qn(Q 0 -Q 4 ) represents that n is the number of oxygen atoms shared by each silicon-oxygen tetrahedron and its adjacent tetrahedron. 0 represents monomer, Q 1 Indicates the end of a dimer or long chain (with a shared oxygen atom), Q 2 Represents Si with two shared oxygen atoms in the middle of the silicon chain, Q 3 Represents Si, Q with three shared oxygen atoms on the silicon chain branch 4 In the Si NMR spectrum, Q 0 The corresponding chemical shift is -68~-76ppm, Q 1 The corresponding chemical shift is -76~-82ppm, Q 2 The corresponding chemical shift is -82~-88ppm, Q 3The corresponding chemical shift is -88~-98ppm, Q 4 The corresponding chemical shift is -98 to -129 ppm. 29 In the Si solid-state NMR spectrum, the size of the Si NMR signal area at different chemical shifts indicates the number of Si atoms with specific structures in the zeolite.

[0070] In some embodiments, the vanadium-containing FER zeolite comprises at least silicon, aluminum, and oxygen as framework atoms, and the zeolite further comprises vanadium, wherein the molar ratio of silicon atoms to aluminum atoms is 2 to 30:1, wherein the mass percentage of vanadium is 0.1 to 3% based on the mass of the zeolite, and wherein the vanadium content is 0.1 to 3% based on the mass of the zeolite. 29 When Si solid-state nuclear magnetic resonance spectroscopy is analyzed, the peak area in the chemical shift range of -110 to -90 ppm accounts for 23% or more and 85% or less of the peak area in the chemical shift range of -125 to -90 ppm.

[0071] In some embodiments, the vanadium-containing FER zeolite is 27 When A1 is analyzed by solid-state nuclear magnetic resonance spectrum, the peak area in the chemical shift range of -50 to 40 ppm accounts for less than 60% of the peak area in the chemical shift range of -50 to 150 ppm.

[0072] The location of vanadium in the zeolite and its specific chemical valence state are not specifically limited. Vanadium can be present within the zeolite framework, outside the zeolite framework, or both within and outside the zeolite framework. In some embodiments, the vanadium content is 0.1% to 3%, for example, 0.1% to 2%, or any value within the above range, for example, 0.2%, 0.3%, 0.5%, 0.7%, 1%, 1.5%, 2%, or 3%. When the vanadium content is less than 0.1%, the low-temperature activity tends to decrease, resulting in insufficient catalytic activity. When the vanadium content exceeds 3%, the acid sites of the zeolite are generally easily destroyed, resulting in reduced catalytic performance. The vanadium-containing FER zeolite may also contain other metal elements, such as one or more alkali metals, alkaline earth metals, rare earth metals, and transition metals, preferably one or more other elements selected from titanium, zirconium, cerium, chromium, manganese, iron, cobalt, zinc, gallium, germanium, bismuth, arsenic, tin, and boron. The location of the other metal elements in the zeolite and their specific chemical valence states are not specifically limited. The other metal elements may be present within the zeolite framework or outside the zeolite framework. Based on the mass of the zeolite, the content of the other metal elements may be 0.05% to 5%, for example, 0.1% to 3%, 0.5% to 1%, or any value within the above range, for example, 0.3%, 0.5%, 0.8%, 1%, 1.5%, 2%, 2.5%, or 3%. The content of the other metal atoms should be no more than 40%, preferably no more than 30%, and more preferably no more than 20%, of the total molar amount of the non-oxygen element atoms in the zeolite.

[0073] In some embodiments, the vanadium-containing FER zeolite of the present disclosure contains cations outside the framework. The cations include hydrogen ions or ammonium ions. In some embodiments, the cations outside the framework also include one or more alkali metal ions and alkaline earth metal ions, for example, one or more of lithium, sodium, potassium, rubidium, cesium, calcium, magnesium, strontium, and barium.

[0074] Preparation of Vanadium-Containing FER Zeolite

[0075] The present disclosure provides a method for preparing the vanadium-containing FER-type zeolite described above, comprising: loading a vanadium species into an FER-type zeolite raw material to obtain the vanadium-containing FER-type zeolite.

[0076] In some embodiments, the preparation method of vanadium-containing FER zeolite includes: removing alkali metal ions in the FER zeolite raw material through an ion exchange method to obtain a treated zeolite, and then loading vanadium on the treated zeolite to obtain the vanadium-containing FER zeolite; or loading vanadium on H-type or ammonium-type FER zeolite to obtain the vanadium-containing FER zeolite.

[0077] In some embodiments, a method for preparing a vanadium-containing FER zeolite comprises: mixing an FER zeolite raw material with a solution of a vanadium source, followed by separation, drying, grinding, and calcining to obtain the vanadium-containing FER zeolite. In some embodiments, the FER zeolite raw material is selected from one of NH4-type FER zeolite and H-type FER zeolite.

[0078] In some embodiments, the FER-type zeolite raw material is prepared by the following steps: (1) mixing a silicon raw material, an aluminum raw material, an optional inorganic base AOH, and water to obtain an aqueous gel; (2) subjecting the aqueous gel to a hydrothermal synthesis reaction, and obtaining a zeolite primary product as the FER-type zeolite raw material through separation, drying, and calcination.

[0079] When the zeolite raw material obtained in step (2) contains alkali metal ions, the zeolite raw product is subjected to ion exchange with ammonium salt to remove part or all of the alkali metal ions in the zeolite raw product, and then calcined to obtain the zeolite raw material.

[0080] In some embodiments, in step (1), the molar ratio of silicon raw material: aluminum raw material: optional inorganic base AOH: water is 2-50SiO2:1Al2O3:2-20A2O:200-2000H2O.

[0081] In some embodiments, the aluminum raw material may use one or more of aluminum sulfate, aluminum nitrate, sodium aluminate, sodium metaaluminate, aluminum oxide, aluminum hydroxide, boehmite, aluminum chloride, aluminum silicate gel, metallic aluminum, and the like.

[0082] In some embodiments, during the preparation of the aqueous gel, the aluminum raw material is prepared as an aluminum raw material solution, preferably by dissolving the aluminum raw material in water. The concentration of the aluminum raw material solution is preferably 5 to 50% by weight, particularly preferably 10 to 40% by weight, for ease of gel preparation and production efficiency.

[0083] It should be noted that the aluminum raw material solution contains substantially no silicon atoms. Here, "substantially no silicon atoms" means that the silicon content in the aluminum raw material solution is 1% by weight or less, and preferably contains no silicon atoms at all.

[0084] In some embodiments, the silicon raw material can be one or more of colloidal silica, amorphous silica, fumed silica, white carbon black, water glass (sodium silicate), trimethylethoxysilane, tetraethyl orthosilicate, aluminum silicate gel, etc., preferably colloidal silica.

[0085] In some embodiments, if the silicon raw material is a liquid, it can be used as long as it is prepared as a 5-60% by weight silica aqueous dispersion, such as silica gel. When preparing other liquids containing silicon raw material, it is preferably prepared as an aqueous solution or dispersion with a silicon raw material 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. As with the aluminum raw material solution, the silicon raw material liquid contains substantially no aluminum atoms. Here, "substantially no aluminum" means that the aluminum content in the silicon raw material liquid is 1% by weight or less, preferably completely absent.

[0086] In some embodiments, as an inorganic base, one or more of alkali metal hydroxides such as sodium hydroxide, potassium hydroxide, rubidium hydroxide, cesium hydroxide, the aluminate of the above-mentioned aluminum raw material, the alkali component in the silicate of the above-mentioned silicon raw material, or the alkali component in the silicate gel can be used. In some embodiments, the raw materials used also contain metal raw materials. In other embodiments, components with a crystallization-promoting effect such as seed crystals can also be added to the raw materials. In the manufacturing process of zeolite, as an alkali metal ion or alkaline earth metal ion, at least one metal ion selected from the group consisting of lithium, sodium, potassium, rubidium, cesium, calcium, magnesium, strontium and barium is preferably used for crystallization. By including these alkali metal ions, crystallization is easy to carry out and by-products (impurity crystals) are not easily generated. It should be noted that when calculating the molar ratio of the components in the gel, the corresponding oxide A2O of the inorganic base AOH is generally used to calculate the molar ratio.

[0087] In some embodiments, during the preparation of the aqueous gel, the inorganic base AOH is prepared into an inorganic base solution for use, preferably, the inorganic base is added to water to prepare the inorganic base solution.

[0088] In some embodiments, an organic template is added to the raw materials for synthesizing the aqueous gel. A template can be used to synthesize zeolites of a specific structure, and of course, FER-type zeolites can be synthesized without a template. In some embodiments, the organic template is selected from one or more of ethylenediamine, isopropylamine, butylamine, octanediamine, cycloheximide, tetramethylammonium hydroxide, pyrrolidine, morpholine, N-methylmorpholine, piperidine, piperazine, N,N'-dimethylpiperazine, 1,4-diazabicyclo(2,2,2)octane, N-methylpiperidine, 3-methylpiperidine, quinuclidine, N-methylpyrrolidone, hexamethyleneimine, methanol, ethanol, ethylene glycol, propanol, glycerol, and isopropanol.

[0089] In some embodiments, the aqueous gel is prepared by uniformly mixing a silicon raw material solution, an aluminum raw material solution, and an inorganic base solution. According to another embodiment, a gel-like mixture is prepared by uniformly mixing a silicon raw material solution, an aluminum raw material solution, an inorganic base solution, an organic template, and a solution containing a metal raw material to prepare the aqueous gel for the next reaction. During the preparation of the gel-like mixture, the rate of addition of the raw material solutions is not limited and can be appropriately selected based on the conditions of use.

[0090] In some embodiments, the water content in 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, from the perspective of the ease of zeolite crystal formation and manufacturing cost. The aqueous gel prepared as above can be hydrothermally synthesized immediately after preparation, but in order to obtain a zeolite with high crystallinity, it is preferably matured for a specific time under specified temperature conditions. The aging temperature is generally 100°C or less, preferably 80°C or less, more preferably 60°C or less, and its lower limit is not particularly limited, and is generally 0°C or more, preferably 10°C or more. For example, room temperature (25°C) can be selected for aging. The aging temperature can be constant or gradually changed during aging. The aging time is not particularly limited, and is generally 2 hours or more, 3 hours or more, 5 hours or more, 8 hours or more, or 12 hours or more, and is generally 30 days or less, 10 days or less, 4 days or less, 2 days or less, or 24 hours or less.

[0091] In some embodiments, the hydrothermal synthesis reaction is carried out as follows: the aqueous gel prepared as described above is placed in a pressure-resistant container, and the temperature is maintained under autogenous pressure, or gas pressure to an extent that does not hinder crystallization, while stirring, or while rotating or shaking the container, or while it is stationary, thereby carrying out hydrothermal synthesis.

[0092] In some embodiments, the reaction temperature during hydrothermal synthesis is typically 90°C or higher, preferably 120°C or higher, more preferably 150°C or higher, and typically 300°C or lower, preferably 250°C or lower, and even more preferably 220°C or lower. The reaction time is not particularly limited, but is typically 2 hours or longer, 6 hours or longer, 12 hours or longer, or 24 hours or longer, and typically 30 days or shorter, 10 days or shorter, 7 days or shorter, 5 days or shorter, or 3 days or shorter. The reaction temperature may be constant or gradually varied during the reaction.

[0093] After the hydrothermal synthesis, the zeolite product is separated from the hydrothermal synthesis reaction solution to obtain the zeolite, which may contain one or more of an organic template or other alkali metals within its pores. The method for separating the zeolite from the hydrothermal synthesis reaction solution is not particularly limited, and typical methods include filtration, decantation, or direct drying.

[0094] In order to remove the organic template and / or alkali metal ions used in the manufacturing process, the zeolite containing the template, etc. separated and recovered from the hydrothermal synthesis reaction solution can be washed with water and dried (for example, dried at 80°C to 100°C for 1 to 12 hours) as needed, and then the template and alkali metal ions can be removed.

[0095] The removal of the template and / or alkali metal can be carried out by liquid phase treatment using an acidic solution, a chemical solution containing a template decomposition component, an ion exchange treatment using a resin, or a thermal decomposition treatment, or a combination of these treatments. Generally, the organic matter (template, etc.) contained can be removed by calcining in air or an inert gas atmosphere containing oxygen, or in an inert gas atmosphere at a temperature of 300°C to 1000°C, or by extraction using an organic solvent such as an ethanol aqueous solution.

[0096] From a manufacturing perspective, it is preferred to remove the template and other agents by calcination. The calcination temperature is preferably 400°C or higher, more preferably 450°C or higher, and even more preferably 500°C or higher, and preferably 900°C or lower, more preferably 850°C or lower, and even more preferably 800°C or lower. During the calcination process, an inert gas, such as nitrogen, may be used. Alternatively, an inert component such as water vapor (e.g., 5% to 10% water vapor) may be added to the gas.

[0097] For the removal of alkali metal ions, the ion exchange capacity of zeolite can be utilized to convert the alkali metal part into H type or NH4 type, and the method can adopt well-known technology. It can be treated with ammonium salts such as NH4NO3, NH4Cl, (NH4)2SO4 or acidic solutions such as hydrochloric acid at room temperature to 100°C and then washed with water. In some embodiments, NH4 type zeolite can be further converted into H type zeolite by roasting. The roasting temperature is preferably above 300°C, more preferably above 350°C, and further preferably above 400°C, preferably below 900°C, more preferably below 800°C, and further preferably below 600°C. Inert gas is introduced into the roasting process, and gases such as nitrogen can be used, or inert components such as water vapor (for example, 5% to 10% water vapor) can be added to the gas. Both NH4 type and H type FER type zeolites can be used to prepare vanadium-containing FER type zeolites.

[0098] In some embodiments, the vanadium source is selected from one or more of ammonium metavanadate, sodium metavanadate, potassium metavanadate, sodium orthovanadate, vanadyl sulfate, vanadyl oxalate, vanadium tetrachloride, vanadium oxytrichloride, and the like.

[0099] The vanadium source solution is prepared by dissolving the vanadium source in a liquid to form a vanadium-containing solution. The vanadium source can be dissolved in water or in an organic solvent, for example, one or more organic solvents such as methanol, ethanol, ethylene glycol, glycerol, and toluene. The pH value of the vanadium-containing solution is generally 1 to 14, preferably 1 to 13, and more preferably 2 to 12. This is because vanadium-containing solutions with low or high pH values ​​are prone to damage or collapse of the zeolite framework during mixing with the zeolite, resulting in reduced denitration activity and thermal stability of the prepared catalyst.

[0100] In some embodiments, the mass ratio of vanadium source (calculated as elemental vanadium): H-type or ammonium FER zeolite is 0.00-0.05 g V: 1 g H-type FER zeolite (for example, ammonium FER zeolite is converted to H-type FER zeolite).

[0101] There is no particular limitation on the mixing method of zeolite and vanadium-containing solution. Generally, stirring, ultrasound and the like can be used to uniformly mix the zeolite and vanadium-containing solution. The mixing temperature is generally between room temperature and 100°C, preferably between room temperature and 80°C, and more preferably between 50 and 80°C. There is no particular limitation on the method for separating the zeolite after mixing. Generally, methods such as filtration, rotary evaporation or direct drying can be cited. The dried zeolite is then calcined, and the calcination temperature is preferably above 300°C, more preferably above 350°C, more preferably above 400°C, preferably below 900°C, more preferably below 800°C, and more preferably below 600°C. The calcination time can be 1 hour to 6 hours, for example, 2 hours, 3 hours, 4 hours or 5 hours. Inert gas can be introduced into the calcination process. Gases such as nitrogen can be used, or inert components such as water vapor (for example, 5% to 10% water vapor) can be added to the gas.

[0102] The roasting equipment disclosed herein is not particularly limited, and common industrial kilns such as muffle furnaces, tunnel kilns, or rotary kilns can be used. From the perspective of the convenience of continuous production, a rotary kiln is preferably used.

[0103] Application of vanadium-containing FER zeolite

[0104] The vanadium-containing FER zeolite disclosed herein can be used directly in powder form or mixed with an adhesive to prepare a mixture containing zeolite. The adhesive used can generally be an inorganic adhesive such as silica, alumina, zirconium oxide, or a polysiloxane-based organic adhesive. A polysiloxane-based organic adhesive refers to an oligomer or polymer having a polysiloxane bond in the main chain, and also includes substances in which a portion of the substituents in the main chain of the polysiloxane bond are hydrolyzed to form hydroxyl groups. The amount of adhesive used is not particularly limited and can generally be 1 to 20% by weight, and in view of the strength during molding, 2 to 15% by weight.

[0105] The vanadium-containing FER-type zeolite disclosed herein or a mixture containing the zeolite can also be used after granulation or molding. The method of granulation or molding is not particularly limited and can be carried out by various well-known methods. Usually, the zeolite mixture is shaped and used as a molded body. The shape of the molded body can be various. For example, when the zeolite disclosed herein is used as a catalyst for purifying nitrogen oxides in exhaust gas from mobile sources (vehicles, ships, etc.), the method of applying the zeolite can be a coating method or a molding method to shape the zeolite into a honeycomb catalyst. The coating method is usually to mix the zeolite with an inorganic adhesive such as silica, alumina or zirconia to make a slurry, and then apply it to the surface of a honeycomb made of an inorganic material such as cordierite, and then dry and burn it. The molding method is usually to mix the zeolite with an inorganic adhesive such as silica, alumina or inorganic fibers such as alumina fiber and glass fiber, and shape it into a honeycomb shape by extrusion or compression, and then dry and burn it.

[0106] In some embodiments, the present disclosure provides a catalytic reactor for purifying nitrogen oxides, which includes the vanadium-containing FER-type zeolite described in any of the aforementioned embodiments or the vanadium-containing FER-type zeolite prepared according to the method described in any of the aforementioned embodiments as a denitration catalyst.

[0107] In some embodiments, the present disclosure provides a nitrogen oxide purification system comprising the aforementioned catalytic reactor for nitrogen oxide purification.

[0108] In some embodiments, the present disclosure provides a denitrification method, comprising using the vanadium-containing FER zeolite described in any of the preceding embodiments or the vanadium-containing FER zeolite prepared according to the method described in any of the preceding embodiments as a denitrification catalyst, and using an alcohol containing 6 or less carbon atoms as a reducing agent to perform selective catalytic reduction denitrification.

[0109] In some embodiments, the present disclosure provides use of the vanadium-containing FER-type zeolite described in any of the aforementioned embodiments or the vanadium-containing FER-type zeolite prepared according to the method described in any of the aforementioned embodiments as a catalyst in selective catalytic reduction denitration.

[0110] In some embodiments, the present disclosure provides the use of the vanadium-containing FER zeolite described in any of the foregoing embodiments or the vanadium-containing FER zeolite prepared according to the method described in any of the foregoing embodiments as a catalyst in a selective catalytic reduction denitrification process using an alcohol containing 6 or less carbon atoms as a reducing agent.

[0111] In some embodiments, the present disclosure provides a method for improving the low-temperature denitration performance and / or durability of an FER-type zeolite, the method comprising loading vanadium on the FER-type zeolite.

[0112] When the vanadium-containing FER zeolite of the present disclosure is used as a catalyst, the zeolite purifies nitrogen oxides by contacting with exhaust gas containing nitrogen oxides. The nitrogen oxides to be purified include nitrogen monoxide, nitrogen dioxide, nitrous oxide, etc. In this article, purifying nitrogen oxides means allowing nitrogen oxides to react on the catalyst and convert into nitrogen and oxygen, etc. At this time, the nitrogen oxides can react directly or coexist with a reducing agent in the catalyst for the purpose of improving the purification efficiency. When a reducing agent is used, the zeolite described herein can make the purification reaction of nitrogen oxides easier to proceed. The alcohol used as the reducing agent can be any compound that has reducing ability at the temperature of the reduction treatment of industrial waste gas. It is preferred to use an alcohol with a carbon number of 6 or less as the reducing agent, such as one or more selected from methanol, ethanol, ethylene glycol, propanol, glycerol, isopropanol, butanol, etc. In a preferred embodiment, the selected alcohol is methanol or ethanol. When the vanadium-containing FER-type zeolite provided in this article is used as a catalyst, it can purify nitrogen oxides contained in various exhaust gases discharged 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.

[0113] Example

[0114] The following examples are provided to facilitate a better understanding of the embodiments of the present disclosure, but are not intended to limit them in any way. The experimental methods used in the following examples are conventional methods unless otherwise specified, and the materials and reagents used are all commercially available unless otherwise specified.

[0115] Solid-state nuclear magnetic resonance (NMR) determination

[0116] The solid-state nuclear magnetic resonance instrument was Bruker Avance III HD 400WB. 27 The Al NMR test had a resonance frequency of 104.3 MHz, a repetition time of 0.1 s, and a rotation frequency of 10 kHz. 29 The Si NMR test was performed with a resonance frequency of 79.5 MHz, a repetition time of 6 s, and a rotation frequency of 5 kHz.

[0117] X-ray diffraction (XRD) determination

[0118] The X-ray diffraction instrument used was a Rigaku MiniFlex 600, 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 zeolite was determined by X-ray diffraction: the ground sample powder was added to a square hole on a glass plate, which was then inserted into the axis of the goniometer. Under the Cu Kα light source, the probe was rotated at a speed of 2θ / min. θ (°) Chemical shift (ppm)

[0119] Catalyst activity evaluation method

[0120] The prepared zeolite was pressed into shape, crushed, and granulated. The granulated zeolite (2 ml) was placed into a fixed-bed flow-through reactor at atmospheric pressure. A gas containing the composition shown in Table 2 was passed over the catalyst layer at 1000 ml / min (space velocity SV = 30,000 / hour) while the catalyst layer was heated. The NOx removal activity of the catalyst was evaluated based on the outlet NO concentration, N2O concentration, and NO2 concentration at different temperatures using the following equation.

[0121] (NO conversion rate) = {(inlet NO concentration) - (outlet NO concentration)} / (inlet NO concentration)

[0122] Table 2

[0123] Hydrothermal aging test

[0124] The prepared zeolite was pressed, crushed, and granulated. The granulated zeolite (2 ml) was placed into a fixed-bed flow reactor at atmospheric pressure, and the catalyst layer was heated to 600°C. Air containing 10% water vapor was circulated over the catalyst layer at 1000 ml / min (space velocity SV = 30,000 / hour) for 12 hours.

[0125] Example 1

[0126] NH4 type FER type zeolite (HSZ-720NHA, SiO2 / Al2O3 molar ratio 18) produced by TOSOH Company of Japan was calcined at 500℃ in air for 2 hours to obtain H type FER type zeolite. In a water bath at 60℃, 0.0345g of ammonium metavanadate was dissolved in 10.8g of water to prepare an ammonium metavanadate aqueous solution, followed by adding 3g of the H type FER type zeolite obtained by the above calcination and stirring evenly. After rotary evaporation at 60℃, the water was removed and the obtained powder was placed in a vacuum drying oven at 100℃ and dried for 12h. After grinding evenly, it was transferred to a muffle furnace and calcined at 500℃ for 4h to obtain zeolite A. The XRD measurement results of zeolite A are shown in Figure 1, which is a FER type zeolite. Zeolite A 29 The Si solid state NMR spectrum is shown in Figure 2. The peak area in the chemical shift range of -110 to -90 ppm accounts for 31% of the peak area in the chemical shift range of -125 to -90 ppm. 27The Al solid-state NMR spectrum is shown in Figure 3. The peak area in the chemical shift range of -50 to 40 ppm accounts for 18% of the total peak area in the chemical shift range of -50 to 150 ppm. Zeolite A has a vanadium content of 0.5 wt%. The methanol-SCR catalytic activity results of zeolite A are shown in Table 3. The methanol-SCR catalytic activity results of zeolite A after hydrothermal aging are shown in Table 4.

[0127] Example 2

[0128] NH4 type FER type zeolite (HSZ-720NHA, SiO2 / Al2O3 molar ratio 18) produced by TOSOH Company of Japan was calcined at 500℃ in air for 2 hours to obtain H type FER type zeolite. Under the condition of 60℃ water bath, 0.052g ammonium metavanadate was dissolved in 10.8g water to prepare ammonium metavanadate aqueous solution, and then 3g of the H type FER type zeolite obtained by the above calcination was added and stirred evenly. After rotary evaporation at 60℃, the water was removed. The obtained powder was placed in a vacuum drying oven at 100 degrees and dried for 12 hours, then ground evenly, transferred to a muffle furnace and calcined at 500℃ for 4 hours to obtain zeolite B. The XRD measurement results of zeolite B are shown in Figure 4, which is a FER type zeolite. Zeolite B 29 The Si solid state NMR spectrum is shown in Figure 5. The peak area in the chemical shift range of -110 to -90 ppm accounts for 34% of the peak area in the chemical shift range of -125 to -90 ppm. 27 The Al solid-state NMR spectrum is shown in Figure 6 . The peak area in the chemical shift range of -50 to 40 ppm accounts for 11% of the peak area in the chemical shift range of -50 to 150 ppm. The vanadium content of zeolite B is 0.75 wt %. The catalytic activity results of zeolite B in methanol-SCR are shown in Table 3.

[0129] Example 3

[0130] NH4 type FER type zeolite (HSZ-720NHA, SiO2 / Al2O3 molar ratio 18) produced by TOSOH Company of Japan was calcined at 500℃ in air for 2 hours to obtain H type FER type zeolite. In a water bath at 60℃, 0.069g of ammonium metavanadate was dissolved in 10.8g of water to prepare an ammonium metavanadate aqueous solution, followed by adding 3g of the H type FER type zeolite obtained by the above calcination and stirring evenly. After rotary evaporation at 60℃, the water was removed. The obtained powder was placed in a vacuum drying oven at 100 degrees and dried for 12 hours, then ground evenly, transferred to a muffle furnace and calcined at 500℃ for 4 hours to obtain zeolite C. The XRD measurement results of zeolite C are shown in Figure 7, which is a FER type zeolite. Zeolite C 29 The Si solid state NMR spectrum is shown in Figure 8. The peak area in the chemical shift range of -110 to -90 ppm accounts for 32% of the peak area in the chemical shift range of -125 to -90 ppm. 27The Al solid-state NMR spectrum is shown in Figure 9 . The peak area in the chemical shift range of -50 to 40 ppm accounts for 18% of the peak area in the chemical shift range of -50 to 150 ppm. Zeolite C has a vanadium content of 1 wt %. The catalytic activity results of zeolite C for methanol-SCR are shown in Table 3.

[0131] Example 4

[0132] 1.0988g of NaAlO2, 0.2656g of NaOH, and 0.7496g of KOH were dissolved in 54g of water and stirred thoroughly to obtain a clear, transparent solution. 6g of fumed silica was then added to the solution while stirring, and the mixture was stirred thoroughly to obtain a gel. The gel composition was 1SiO2: 0.067Al2O3: 0.0332Na2O: 0.0668K2O: 30H2O. After stirring and aging at room temperature for 12 hours, the gel was placed in a heat- and pressure-resistant container and subjected to hydrothermal synthesis at 165°C for 72 hours. The reaction solution was then cooled. The resulting powder was recovered by filtration, dried at 100°C for 2 hours, and then transferred to a muffle furnace and calcined at 600°C in air for 6 hours to obtain zeolite D1.

[0133] 1.3 g of ammonium chloride was dissolved in 13 g of water, and then 4 g of the FER zeolite obtained above was added to form a slurry. The mixture was reacted at 80°C for 2 hours to perform ion exchange. The reaction solution was cooled, filtered, and the resulting powder was recovered and dried at 100°C for 2 hours. After repeating the ion exchange process twice more, the resulting powder was calcined in air at 500°C for 2 hours to obtain H-type zeolite D2.

[0134] In a 60°C water bath, 0.0345g of ammonium metavanadate was dissolved in 10.8g of water to prepare an ammonium metavanadate aqueous solution. Subsequently, 3g of the H-type zeolite D2 obtained by calcination was added and stirred evenly. After rotary evaporation at 60°C, the water was removed. The resulting powder was placed in a vacuum drying oven at 100°C for 12 hours and then ground evenly. It was transferred to a muffle furnace and calcined at 500°C for 4 hours to obtain zeolite D. The XRD measurement results of zeolite D are shown in Figure 10, indicating that it is an FER type zeolite. Zeolite D 29 The Si solid state NMR spectrum is shown in Figure 11. The peak area in the chemical shift range of -110 to -90 ppm accounts for 42% of the peak area in the chemical shift range of -125 to -90 ppm. 27 The Al solid-state NMR spectrum is shown in Figure 12 . The peak area in the chemical shift range of -50 to 40 ppm accounts for 16% of the peak area in the chemical shift range of -50 to 150 ppm. Zeolite D has a SiO₂ / Al₂O₃ molar ratio of 17 and a vanadium content of 0.5 wt%. The catalytic activity results for methanol-SCR of zeolite D are shown in Table 3.

[0135] Example 5

[0136] After calcining NH4-type FER-type zeolite (HSZ-720NHA, SiO2 / Al2O3 molar ratio 18) produced by TOSOH Company of Japan at 500°C in air for 2 hours, H-type FER-type zeolite was obtained. 0.103g of ammonium metavanadate and 0.221g of oxalic acid were dissolved in 10.8g of water to prepare a vanadium-containing solution. Subsequently, 3g of the calcined H-type FER-type zeolite was added, stirred evenly, and filtered to remove moisture. The obtained powder was placed in a vacuum drying oven at 100 degrees Celsius and dried for 12 hours. After grinding, it was transferred to a muffle furnace and calcined at 500°C for 4 hours to obtain zeolite E. The XRD measurement results of zeolite E are shown in Figure 13, which shows that it is a FER-type zeolite. Zeolite E 29 The Si solid state NMR spectrum is shown in Figure 14. The peak area in the chemical shift range of -110 to -90 ppm accounts for 36% of the peak area in the chemical shift range of -125 to -90 ppm. 27 The Al solid-state NMR spectrum is shown in Figure 15 . The peak area in the chemical shift range of -50 to 40 ppm accounts for 12% of the total peak area in the chemical shift range of -50 to 150 ppm. Zeolite E has a vanadium content of 0.5 wt %. The methanol-SCR catalytic activity results of zeolite E are shown in Table 3. The methanol-SCR catalytic activity results of zeolite E after hydrothermal aging are shown in Table 4.

[0137] Example 6

[0138] A mixed solution of 1.367g solid sodium metaaluminate (Al2O3 ≥ 45%) and 0.896g potassium hydroxide was dissolved in 40g deionized water. 20g of silica sol was then added dropwise to the stirred solution and stirred thoroughly to produce an aqueous gel. The composition of the aqueous gel was: 17SiO2:1Al2O3:1.39Na2O:1.32K2O:510H2O. After stirring and aging at room temperature for 12 hours, the aqueous gel was placed in a heat- and pressure-resistant container and subjected to hydrothermal synthesis at 180°C for 48 hours. The reaction solution was then cooled. The resulting powder was recovered by filtration and dried at 100°C for 2 hours to obtain zeolite F1.

[0139] Dissolve 1.39g of ammonium chloride in 15g of water, then add 5g of zeolite F1 to form a slurry. Ion exchange is performed at 80°C for 2 hours. The reaction mixture is cooled, filtered, and the resulting powder is recovered and dried at 100°C for 2 hours. Repeat this ion exchange process twice more, and then calcine the resulting powder in air at 500°C for 2 hours to obtain H-type zeolite F2.

[0140] In a 60°C water bath, 0.052g of ammonium metavanadate was dissolved in 10.8g of water to prepare an ammonium metavanadate aqueous solution. Subsequently, 3g of the calcined zeolite F2 was added and mixed for 2h under the same conditions. The water was removed by rotary evaporation at 60°C. The resulting powder was placed in a vacuum drying oven at 100°C for 12h and then ground evenly. It was transferred to a muffle furnace and calcined at 500°C for 4h to obtain zeolite F. The XRD measurement results of zeolite F are shown in Figure 16, indicating that it is an FER type zeolite. Zeolite F 29 The Si solid state NMR spectrum is shown in Figure 17. The peak area in the chemical shift range of -110 to -90 ppm accounts for 47% of the peak area in the chemical shift range of -125 to -90 ppm. 27 The Al solid-state NMR spectrum is shown in Figure 18 . The peak area in the chemical shift range of -50 to 40 ppm accounts for 32% of the peak area in the chemical shift range of -50 to 150 ppm. The vanadium content of the zeolite is 0.5 wt %. Zeolite F has a SiO2 / Al2O3 molar ratio of 12 and a vanadium content of 0.75 wt %. The catalytic activity results of zeolite F for methanol-SCR are shown in Table 3. The catalytic activity results of zeolite F for methanol-SCR after hydrothermal aging are shown in Table 4.

[0141] Example 7

[0142] 1.367g of solid sodium metaaluminate (Al2O3 ≥ 45%) and 0.896g of potassium hydroxide were dissolved in 40g of deionized water to form a mixed solution. 20g of silica sol was then added dropwise to the stirred solution and stirred thoroughly to produce an aqueous gel. The aqueous gel composition was: 17SiO2:1Al2O3:1.39Na2O:1.32K2O:510H2O. After stirring and aging at room temperature for 12 hours, the aqueous gel was placed in a heat- and pressure-resistant container and subjected to hydrothermal synthesis at 180°C for 48 hours. The reaction solution was then cooled. The resulting powder was recovered by filtration and dried at 100°C for 2 hours to obtain zeolite G1.

[0143] Dissolve 1.39g of ammonium chloride in 15g of water, then add 5g of zeolite G1 to form a slurry. Ion exchange is performed at 80°C for 2 hours. The reaction mixture is cooled, filtered, and the resulting powder is recovered and dried at 100°C for 2 hours. Repeat this ion exchange process twice more, and then calcine the resulting powder in air at 500°C for 2 hours to obtain H-type zeolite G2.

[0144] In a 60°C water bath, 0.069g of ammonium metavanadate was dissolved in 10.8g of water to prepare an ammonium metavanadate aqueous solution. Subsequently, 3g of the calcined zeolite G2 was added and mixed for 2h under the same conditions. The water was removed by rotary evaporation at 60°C. The obtained powder was placed in a vacuum drying oven at 100°C for 12h and then ground evenly. It was transferred to a muffle furnace and calcined at 500°C for 4h to obtain zeolite G. The XRD measurement results of zeolite G are shown in Figure 19, which shows that it is an FER type zeolite. Zeolite G 29 The Si solid state NMR spectrum is shown in Figure 20. The peak area in the chemical shift range of -110 to -90 ppm accounts for 48% of the peak area in the chemical shift range of -125 to -90 ppm. 27 The Al solid-state NMR spectrum is shown in Figure 21 . The peak area in the chemical shift range of -50 to 40 ppm accounts for 36% of the peak area in the chemical shift range of -50 to 150 ppm. Zeolite G has a SiO₂ / Al₂O₃ molar ratio of 12 and a vanadium content of 1 wt%. The catalytic activity results for methanol-SCR using zeolite G are shown in Table 3.

[0145] Example 8

[0146] 1.23g of liquid sodium metaaluminate (Al2O3 ≥ 50%) and 0.896g of potassium hydroxide were dissolved in 40g of deionized water to form a mixed solution. 20g of silica sol was then added dropwise to the stirred solution and stirred thoroughly to produce an aqueous gel. The composition of the aqueous gel was: 17SiO2:1Al2O3:1.24Na2O:1.32K2O:510H2O. After stirring and aging at room temperature for 12 hours, the aqueous gel was placed in a heat- and pressure-resistant container and subjected to hydrothermal synthesis at 180°C for 48 hours. The reaction solution was then cooled. The resulting powder was recovered by filtration and dried at 100°C for 2 hours to obtain zeolite H1.

[0147] Dissolve 1.39g of ammonium chloride in 15g of water, then add 5g of zeolite H1 to form a slurry. Ion exchange is performed at 80°C for 2 hours. The reaction mixture is cooled, filtered, and the resulting powder is recovered and dried at 100°C for 2 hours. Repeat this ion exchange process twice more, and then calcine the resulting powder in air at 500°C for 4 hours to obtain H-type zeolite H2.

[0148] Under the condition of a 60°C water bath, 0.0345g of ammonium metavanadate was dissolved in 10.8g of water to prepare an ammonium metavanadate aqueous solution. Subsequently, 3g of the zeolite H2 obtained by calcination was added under the same conditions and mixed for 2h. After removing the water by rotary evaporation at 60°C, the obtained powder was placed in a vacuum drying oven at 100°C for 12h and then ground evenly. After being transferred to a muffle furnace and calcined at 500°C for 4h, zeolite H was obtained. The XRD measurement results of zeolite H are shown in Figure 22, which shows that it is an FER type zeolite. Zeolite H 29The Si solid state NMR spectrum is shown in Figure 23. The peak area in the chemical shift range of -110 to -90 ppm accounts for 41% of the peak area in the chemical shift range of -125 to -90 ppm. 27 The Al solid-state NMR spectrum is shown in Figure 24 . The peak area in the chemical shift range of -50 to 40 ppm accounts for 22% of the peak area in the chemical shift range of -50 to 150 ppm. Zeolite H has a SiO2 / Al2O3 molar ratio of 12 and a vanadium content of 0.5 wt%. The catalytic activity of zeolite H in methanol-SCR is shown in Table 3.

[0149] Example 9

[0150] 1.16g of solid sodium metaaluminate (Al2O3 ≥ 53%) and 0.896g of potassium hydroxide were dissolved in 37.9g ​​of deionized water to form a mixed solution. 20g of silica sol was then added dropwise to the stirred solution and stirred thoroughly to produce an aqueous gel. The aqueous gel composition was: 17SiO2:1Al2O3:1.17Na2O:1.32K2O:510H2O. After stirring and aging at room temperature for 12 hours, the aqueous gel was placed in a heat- and pressure-resistant container and subjected to hydrothermal synthesis at 180°C for 48 hours. The reaction solution was then cooled. The resulting powder was recovered by filtration and dried at 100°C for 2 hours to obtain zeolite I1.

[0151] Dissolve 1.39g of ammonium chloride in 15g of water, then add 5g of zeolite I1 to form a slurry. Ion exchange is performed at 80°C for 2 hours. The reaction mixture is cooled, filtered, recovered, and dried at 100°C for 2 hours. Repeat this ion exchange process twice more, and then calcine the resulting powder in air at 500°C for 4 hours to obtain H-type zeolite I2.

[0152] In a 60°C water bath, 0.0345g of ammonium metavanadate was dissolved in 10.8g of water to prepare an ammonium metavanadate aqueous solution. Subsequently, 3g of the zeolite I2 obtained by calcination was added under the same conditions and mixed for 2h. The water was removed by rotary evaporation at 60°C. The obtained powder was placed in a vacuum drying oven at 100°C for 12h and then ground evenly. It was transferred to a muffle furnace and calcined at 500°C for 4h to obtain zeolite I. The XRD measurement results of zeolite I are shown in Figure 25, which is an FER type zeolite. Zeolite I 29 The Si solid state NMR spectrum is shown in Figure 26. The peak area in the chemical shift range of -110 to -90 ppm accounts for 42% of the peak area in the chemical shift range of -125 to -90 ppm. 27The Al solid-state NMR spectrum is shown in Figure 27 . The peak area in the chemical shift range of -50 to 40 ppm accounts for 27% of the peak area in the chemical shift range of -50 to 150 ppm. Zeolite I has a SiO2 / Al2O3 molar ratio of 12 and a vanadium content of 0.5 wt%. The catalytic activity results for methanol-SCR of zeolite I are shown in Table 3.

[0153] Example 10

[0154] 1.39 g of ammonium chloride was dissolved in 15 g of water, and then 5 g of zeolite I1 prepared in Example 9 was added to form a slurry. The mixture was reacted at 80°C for 2 hours to perform ion exchange. The reaction solution was cooled, filtered, recovered, and dried at 100°C for 2 hours to obtain ammonium zeolite J2.

[0155] Under the condition of 60℃ water bath, 0.0345g ammonium metavanadate was dissolved in 10.8g water to prepare ammonium metavanadate aqueous solution, and then 3g ammonium type zeolite J2 was added and mixed for 2h. After rotary evaporation at 60℃, the water was removed. The obtained powder was placed in a vacuum drying oven at 100℃ and dried for 12h. After grinding, it was transferred to a muffle furnace and calcined at 500℃ for 4h to obtain zeolite J. The XRD measurement results of zeolite J showed that it was FER type zeolite. 29 The results of Si solid state nuclear magnetic resonance spectrum test show that the peak area in the chemical shift range of -110 to -90 ppm accounts for 42% of the peak area in the chemical shift range of -125 to -90 ppm. 27 Al solid-state nuclear magnetic resonance spectroscopy results show that the peak area in the chemical shift range of -50 to 40 ppm accounts for 27% of the peak area in the chemical shift range of -50 to 150 ppm. Zeolite J has a SiO2 / Al2O3 molar ratio of 12 and a vanadium content of 0.5 wt%. The catalytic activity of zeolite J in methanol-SCR is shown in Table 3.

[0156] Comparative Example 1

[0157] After calcining NH4 type FER type zeolite (HSZ-720NHA, SiO2 / Al2O3 molar ratio 18) in air at 500℃ for 2 hours, zeolite K was obtained. The XRD measurement results of zeolite K are shown in Figure 28, which shows that it is an FER type zeolite. 29 The Si solid state NMR spectrum is shown in Figure 29. The peak area in the chemical shift range of -110 to -90 ppm accounts for 23% of the peak area in the chemical shift range of -125 to -90 ppm. 27 The Al solid-state NMR spectrum is shown in Figure 30 , where the peak area in the chemical shift range of -50 to 40 ppm accounts for 4% of the peak area in the chemical shift range of -50 to 150 ppm. The catalytic activity results of zeolite K for methanol-SCR are shown in Table 3.

[0158] Comparative Example 2

[0159] NH4 type FAU type zeolite (Tianjin Nanhua Catalyst Co., Ltd., SiO2 / Al2O3 molar ratio 5.2) was calcined at 500°C in air for 2 hours to obtain H type FAU type zeolite. In a water bath at 60°C, 0.0345g of ammonium metavanadate was dissolved in 10.8g of water to prepare an ammonium metavanadate aqueous solution, followed by adding 3g of the H type FAU type zeolite obtained by the above calcination and stirring evenly. After rotary evaporation at 60°C, the water was removed and the obtained powder was placed in a vacuum drying oven at 100°C for 12 hours and then ground evenly. It was transferred to a muffle furnace and calcined at 500°C for 4 hours to obtain zeolite L. The XRD measurement results of zeolite L are shown in Figure 31, which is a FAU type zeolite. Zeolite L 29 The Si solid state NMR spectrum is shown in Figure 32. The peak area in the chemical shift range of -110 to -90 ppm accounts for 86% of the peak area in the chemical shift range of -125 to -90 ppm. 27 The Al solid-state NMR spectrum is shown in Figure 33 . The peak area in the chemical shift range of -50 to 40 ppm accounts for 30% of the peak area in the chemical shift range of -50 to 150 ppm. Zeolite L has a vanadium content of 0.5 wt %. The catalytic activity results for methanol-SCR using zeolite L are shown in Table 3.

[0160] Comparative Example 3

[0161] NH4 type MFI type zeolite (Tianjin Nanhua Catalyst Co., Ltd., SiO2 / Al2O3 molar ratio 38) was calcined at 500°C in air for 2 hours to obtain H type MFI type zeolite. Under 60°C water bath conditions, 0.0345g of ammonium metavanadate was dissolved in 10.8g of water to prepare an ammonium metavanadate aqueous solution, followed by adding 3g of the H type MFI type zeolite obtained by the above calcination and stirring evenly. After rotary evaporation at 60°C, the water was removed and the obtained powder was placed in a vacuum drying oven at 100°C for 12 hours and then ground evenly. It was transferred to a muffle furnace and calcined at 500°C for 4 hours to obtain zeolite M. The XRD measurement results of zeolite M are shown in Figure 34, which is an MFI type zeolite. Zeolite M 29 The Si solid state NMR spectrum is shown in Figure 35. The peak area in the chemical shift range of -110 to -90 ppm accounts for 21% of the peak area in the chemical shift range of -125 to -90 ppm. 27 The Al solid-state NMR spectrum is shown in Figure 36 . The peak area in the chemical shift range of -50 to 40 ppm accounts for 19% of the peak area in the chemical shift range of -50 to 150 ppm. Zeolite M has a vanadium content of 0.5 wt %. The methanol-SCR catalytic activity results of zeolite M are shown in Table 3.

[0162] Comparative Example 4

[0163] 1.23g of solid sodium metaaluminate (Al2O3 ≥ 50%) and 0.896g of potassium hydroxide were dissolved in 40g of deionized water to form a mixed solution. 20g of silica sol was then added dropwise to the stirred solution and stirred thoroughly to produce an aqueous gel. The aqueous gel composition was: 17SiO2:1Al2O3:1.4Na2O:1.32K2O:510H2O. After stirring and aging at room temperature for 12 hours, the aqueous gel was placed in a heat- and pressure-resistant container and subjected to hydrothermal synthesis at 180°C for 48 hours. The reaction solution was then cooled. The resulting powder was recovered by filtration and dried at 100°C for 2 hours to obtain zeolite N1.

[0164] Dissolve 1.3g of ammonium chloride in 13g of water, then add 4g of zeolite N1 to form a slurry and react at 80℃ for 2 hours to perform ion exchange. Cool the reaction solution, filter and recover the resulting powder, and dry it at 100℃ for 2 hours. Repeat the above ion exchange twice, and then calcine the resulting powder in air at 500℃ for 2 hours to obtain zeolite N. The XRD measurement results of zeolite N are shown in Figure 37, which shows that it is an FER type zeolite. Zeolite N 29 The Si solid state NMR spectrum is shown in Figure 38. The peak area in the chemical shift range of -110 to -90 ppm accounts for 44% of the peak area in the chemical shift range of -125 to -90 ppm. 27 The Al solid-state NMR spectrum is shown in Figure 39 . The peak area in the chemical shift range of -50 to 40 ppm accounts for 13% of the peak area in the chemical shift range of -50 to 150 ppm. The SiO2 / Al2O3 molar ratio of zeolite N is 12. The methanol-SCR catalytic activity results of zeolite N are shown in Table 3.

[0165] Comparative Example 5

[0166] FER type zeolite O was obtained according to the preparation method of Example 2 in patent document WO2021 / 114208A1. 29 The Si solid state NMR spectrum is shown in Figure 40. The peak area in the chemical shift range of -110 to -90 ppm accounts for 36% of the peak area in the chemical shift range of -125 to -90 ppm. 27 The Al solid-state NMR spectrum is shown in Figure 41 , where the peak area in the chemical shift range of -50 to 40 ppm accounts for 23% of the peak area in the chemical shift range of -50 to 150 ppm. The catalytic activity results of zeolite O for methanol-SCR are shown in Table 3.

[0167] The catalytic activity results of zeolite O for methanol-SCR after hydrothermal aging test are shown in Table 4.

[0168] Comparative Example 6

[0169] 0.28 g of oxalic acid was dissolved in 6 g of water, 0.13 g of ammonium metavanadate and 0.54 g of ammonium metatungstate were added, and the mixture was evenly mixed. Then, 10 g of anatase-type titanium dioxide powder was added and stirred for 2 h. The mixture was placed in a drying oven at 110 ° C and ground evenly while being dried. The mixture was transferred to a muffle furnace and calcined at 500 ° C for 4 h to obtain vanadium-based oxide P with a vanadium content of 1 wt%.

[0170] Table 3

[0171] Table 4

[0172] From the results of the above examples and comparative examples, it can be seen that all the embodiments of the vanadium-containing FER zeolite denitration catalyst of the present disclosure adopt 29 When analyzed by Si solid-state nuclear magnetic resonance spectroscopy, the peak area in the chemical shift range of -110 to -90 ppm accounts for more than 23% and less than 85% of the peak area in the chemical shift range of -125 to -90 ppm. Compared with the vanadium-free zeolite (Comparative Examples 1 and 4) whose peak area in the chemical shift range of -110 to -90 ppm accounts for more than 23% and less than 85% of the peak area in the chemical shift range of -125 to -90 ppm, and the vanadium-containing zeolite (Comparative Examples 2 and 3) whose peak area in the chemical shift range of -110 to -90 ppm accounts for more than 85% and less than 23% of the peak area in the chemical shift range of -125 to -90 ppm, the embodiments of the present disclosure all exhibited superior methanol-SCR denitrification performance at low temperatures (225 to 275°C). Compared with the vanadium-free zeolite prepared in Example 2 disclosed in patent document WO2021114208A1 (Comparative Example 5), the embodiments of the present disclosure can also achieve better methanol-SCR denitrification performance under low temperature conditions (225-275°C).

[0173] Although the embodiments described herein are described with reference to specific embodiments, it should be understood that various modifications and variations can be made thereto by those skilled in the art without departing from the scope and spirit of the present disclosure.

Claims

1. A vanadium-containing FER zeolite, characterized in that: The zeolite contains at least silicon, aluminum and oxygen as framework atoms, The molar ratio of silicon atoms to aluminum atoms is 2 to 30:

1. wherein the mass percentage of vanadium is 0.1 to 3% based on the mass of the zeolite, and The zeolite is treated 29 When analyzing the Si solid nuclear magnetic resonance spectrum, the peak area in the chemical shift range of -110 to -90 ppm accounts for 23% or more and 85% or less of the peak area in the chemical shift range of -125 to -90 ppm.

2. The vanadium-containing FER zeolite according to claim 1, wherein The zeolite is treated 27 When A1 solid state nuclear magnetic resonance spectrum is analyzed, the peak area in the chemical shift range of -50 to 40 ppm accounts for less than 60% of the peak area in the chemical shift range of -50 to 150 ppm.

3. The vanadium-containing FER-type zeolite according to claim 1 or 2, wherein: The vanadium is in the framework of the zeolite and / or outside the framework of the zeolite, for example outside the framework of the zeolite.

4. The vanadium-containing FER zeolite according to any one of claims 1 to 3, wherein There are cations outside the framework of the zeolite, for example, the cations are hydrogen ions or ammonium ions.

5. A method for preparing the vanadium-containing FER zeolite according to any one of claims 1 to 4, characterized in that: The method comprises: removing alkali metal ions in a FER zeolite raw material by an ion exchange method to obtain a treated zeolite, and then loading vanadium on the treated zeolite to obtain the vanadium-containing FER zeolite; or loading vanadium on an H-type or ammonium-type FER zeolite to obtain the vanadium-containing FER zeolite.

6. The method according to claim 5, wherein: The vanadium is provided by a vanadium source, and the vanadium source is selected from ammonium metavanadate, sodium metavanadate, potassium metavanadate, sodium orthovanadate, vanadyl sulfate, vanadyl oxalate, vanadium tetrachloride, vanadium oxytrichloride or any combination thereof. Preferably, the vanadium source is in the form of a solution, and more preferably, the vanadium source is in the form of an aqueous solution; Optionally, the mass ratio of vanadium source: H-type or ammonium-type FER zeolite is 0.0005-0.05 g V: 1 g H-type FER zeolite.

7. A catalytic reactor for purifying nitrogen oxides, characterized in that: The catalytic reactor comprises the vanadium-containing FER-type zeolite according to any one of claims 1 to 4 or the vanadium-containing FER-type zeolite prepared according to the method of claim 5 or 6 as a denitration catalyst.

8. A nitrogen oxide purification system, characterized in that: The system is provided with the catalytic reactor for purifying nitrogen oxides as claimed in claim 7.

9. A denitration method, characterized in that: The method comprises using the vanadium-containing FER zeolite according to any one of claims 1 to 4 or the vanadium-containing FER zeolite prepared according to the method of claim 5 or 6 as a denitration catalyst, and using an alcohol containing 6 or less carbon atoms as a reducing agent for selective catalytic reduction denitration.

10. A method for improving the low-temperature denitration performance and / or durability of FER-type zeolite, characterized in that: The method includes loading vanadium onto the FER-type zeolite.

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