SSZ-13 molecular sieve as well as preparation method and application thereof

Abstract

The invention relates to the field of molecular sieve preparation, and discloses an SSZ-13 molecular sieve as well as a preparation method and application thereof. The preparation method comprises the following steps: 1) performing a first crystallization reaction on a first mixture containing a first aluminum source, a first silicon source, a potassium source, an organic template agent and water to obtain a potassium type accelerant; (2) a mixture containing a second aluminum source, a second silicon source, an alkali source, an organic template agent, water and the potassium type accelerant is subjected to a second crystallization reaction, a crystallization product is obtained, in the potassium type accelerant, the molar ratio of SiO2 to Al2O3 to K2O to R to H2O is 1: (0.1-0.4): (0.6-1.5): (0.02-0.15): (60-140), and R is the organic template agent. According to the method, the production of the SSZ-13 molecular sieve can be stably realized, the prepared SSZ-13 molecular sieve has relatively dispersed micron-sized crystals which are approximately in a regular hexahedron shape, and a catalyst prepared from the molecular sieve has excellent catalytic activity and good hydrothermal stability at the same time.

Description

Technical Field

[0001] This invention relates to the field of molecular sieve preparation, specifically to an SSZ-13 molecular sieve, its preparation method, and its application. Background Technology

[0002] With rapid economic development, NO x Emissions are also growing at an unprecedented rate. Nitrogen oxides (NOx) from both mobile and stationary sources... x This will bring a series of environmental problems, such as NO. x In the atmosphere, it is oxidized into nitric acid, which is one of the causes of acid rain; NO x NO reacts photochemically with other pollutants in the atmosphere, causing photochemical smog pollution; x It can also reduce ozone in the stratosphere, thereby increasing the amount of ultraviolet radiation reaching Earth. In addition, NO... x It can also enter the deep parts of the lungs through respiration, causing diseases such as bronchitis or emphysema, and endangering human health.

[0003] NO x The issue of NO pollution control is urgent. Among these, the selective catalytic reduction of NO by ammonia is crucial. x (NH3-SCR) technology is an effective method for detecting NO. x Removal technology. Commercially available V2O5-WO3 / TiO2 catalysts have been widely used for stationary source denitrification and have shown excellent NO removal performance in the medium temperature range (300-400℃). x Removal efficiency. However, this catalyst exhibits some drawbacks, such as low high-temperature selectivity, narrow operating temperature range, and vanadium toxicity.

[0004] SSZ-13 molecular sieves are favored in NO due to their large specific surface area, abundant ion exchange sites, strong surface acidic sites, and molecular shape selectivity. x It is widely used in denitrification, especially in diesel vehicle denitrification. SSZ-13 molecular sieve was first prepared by American chemist Zones in the mid-1980s through hydrothermal synthesis. Since then, many studies have been carried out to optimize and improve the synthesis process of SSZ-13 molecular sieve. However, to date, there are very few companies that can mass-produce SSZ-13 molecular sieve powder. The main reason is that the crystal form of SSZ-13 molecular sieve is difficult to control, and it is difficult to achieve a balance between activity and stability in SSZ-13 catalysts that are further loaded with metals. For example, Cu-SSZ-13 catalysts with excellent activity usually have poor hydrothermal stability.

[0005] In this regard, Huawang Zhao et al. synthesized SSZ-13 molecular sieves using SAPO-34 microcrystals as seed crystals, and further prepared Cu-SSZ-13 catalysts. Compared with the products synthesized using SSZ-13 microcrystals as seed crystals, the hydrothermal stability of the obtained catalysts was significantly improved (Journal of Catalysis 377(2019):218-223,DOI:10.1016 / j.jcat.2019.07.023); For example, Yunzheng Wang et al. used SAPO-18 microcrystals as seed crystals to increase the aluminum pair content in low silica-alumina ratio SSZ-13 molecular sieves based on the "RNA" transcription mechanism, thereby effectively improving the hydrothermal stability of Cu-SSZ-13 catalysts (Angewandte62(2023):e202306174,DOI:10.1002 / anie.202306174). However, both of the above methods use phosphorus-containing seed crystals, which inevitably leads to a significant increase in the difficulty of treating production wastewater.

[0006] In addition, there are reports of using innovative methods such as the mixed template method to prepare SSZ-13 molecular sieves in the existing technology. However, such mixed template agents have not yet been industrialized, and the combination of multiple template agents is not conducive to the subsequent reuse of mother liquor, so it is not suitable for large-scale industrial production.

[0007] On the other hand, most of the SSZ-13 molecular sieves reported in current research are nanoscale aggregated irregular crystal particles, whose structure and performance are unstable, and their service application prospects are unclear.

[0008] Based on the current situation, developing an SSZ-13 molecular sieve with excellent activity and good hydrothermal stability is an important task that urgently needs to be completed. Summary of the Invention

[0009] The purpose of this invention is to overcome the difficulty in simultaneously achieving high activity and hydrothermal stability in existing SSZ-13 molecular sieves, and to provide an improved method for preparing SSZ-13 molecular sieves. This method does not require the introduction of substances such as phosphorus that significantly increase the difficulty of wastewater treatment, nor does it require the use of complex combined template agents. It can stably achieve the production of SSZ-13 molecular sieves, and the SSZ-13 molecular sieves prepared in this way have relatively dispersed micron-sized and nearly hexahedral crystals. The catalyst prepared by this molecular sieve has both excellent catalytic activity and good hydrothermal stability.

[0010] To achieve the above objectives, the present invention provides a method for preparing SSZ-13 molecular sieve, which includes the following steps:

[0011] 1) A first mixture containing a first aluminum source, a first silicon source, a potassium source, an organic template agent, and water is subjected to a first crystallization reaction to obtain a potassium-type accelerator;

[0012] 2) A mixture containing a second aluminum source, a second silicon source, an alkali source, an organic template agent, water, and the potassium-type accelerator is subjected to a second crystallization reaction to obtain a crystallized product.

[0013] In the potassium-type accelerator, the molar ratio of SiO2:Al2O3:K2O:R:H2O is 1:0.1-0.4:0.6-1.5:0.02-0.15:60-140, and R is an organic template agent.

[0014] Preferably, in step 2), a second mixture containing a second aluminum source, a second silicon source, an alkali source, an organic template agent, and water is contacted with the potassium-type promoter to carry out the second crystallization reaction.

[0015] Preferably, in the potassium-type accelerator, the molar ratio of SiO2:Al2O3:K2O:R:H2O is 1:0.1-0.3:0.6-1.2:0.02-0.10:60-120, where R is an organic template agent.

[0016] Preferably, in the second mixture, the molar ratio of the second silicon source (calculated as SiO2), the second aluminum source (calculated as Al2O3), the alkali source (calculated as metal oxide), the organic template R, and H2O is 1:0.02-0.17:0.05-0.5:0.01-0.15:5-90; more preferably, it is 1:0.04-0.08:0.2-0.4:0.04-0.05:30-40.

[0017] Preferably, in step 2), the amount of the potassium-type accelerator is 0.02-1% by weight of the second mixture, more preferably 0.05-0.1% by weight.

[0018] Preferably, in step 1), the first crystallization reaction is a dynamic crystallization reaction.

[0019] Preferably, the conditions for the first crystallization reaction include: a temperature of 20-120℃, a time of 5-50h, and a rotation speed of 50-500rpm; more preferably, the conditions for the first crystallization reaction include: reacting at a rotation speed of 100-300rpm at 30-90℃ for 2-30h, followed by reacting at 90-150℃ for 0.2-10h; even more preferably, the conditions for the first crystallization reaction include: reacting at a rotation speed of 150-200rpm at 40-80℃ for 5-30h, followed by reacting at 90-120℃ for 0.5-4h.

[0020] Preferably, in step 2), the conditions for the second crystallization reaction include: a temperature of 100-220°C and a time of 5-144h; more preferably, the conditions for the second crystallization reaction include: a temperature of 120-180°C and a crystallization time of 24-96h.

[0021] Preferably, the second crystallization reaction is a static crystallization reaction.

[0022] Preferably, the method further includes drying and calcining the crystallized product obtained in step 2).

[0023] Preferably, the drying conditions include a temperature of 50-150°C and a time of 8-24 hours.

[0024] Preferably, the calcination conditions include: a temperature of 400-700℃ and a time of 2-10h.

[0025] Preferably, the first aluminum source is selected from aluminum hydroxide and / or aluminum sulfate.

[0026] Preferably, the first silicon source is selected from one or more of silica sol, silica, and amorphous silica.

[0027] Preferably, the potassium source is selected from one or more of potassium hydroxide, potassium sulfate, potassium chloride, and potassium nitrate.

[0028] Preferably, the organic template agent is selected from one or more of N,N,N-trimethyl-adamantyl ammonium hydroxide, benzyltrimethyl ammonium hydroxide, N,N,N-dimethylethylcyclohexyl ammonium bromide, tetraethyl ammonium hydroxide, tetramethyl ammonium hydroxide and choline chloride; more preferably, it is N,N,N-trimethyl-adamantyl ammonium hydroxide.

[0029] Preferably, the second aluminum source is selected from one or more of aluminum hydroxide, aluminum sulfate, sodium aluminate, and aluminum oxide.

[0030] Preferably, the second silicon source is selected from one or more of silica sol, silica, water glass, sodium silicate, potassium silicate, and amorphous silica.

[0031] Preferably, the alkali source is selected from sodium hydroxide and / or potassium hydroxide.

[0032] A second aspect of the present invention provides an SSZ-13 molecular sieve, wherein the SSZ-13 molecular sieve is prepared by the method described in the first aspect of the present invention.

[0033] Preferably, the SSZ-13 molecular sieve has a near-hexahedral structure, and the size of the SSZ-13 molecular sieve is 0.5-1.5 μm, more preferably 0.8-1.2 μm.

[0034] Preferably, the silicon-to-aluminum ratio of the SSZ-13 molecular sieve is 9-25:1; more preferably, it is 14-22:1.

[0035] Preferably, the crystallinity of the SSZ-13 molecular sieve is 98-106%; more preferably, it is 104-106%.

[0036] A third aspect of the present invention provides a Cu-SSZ-13 molecular sieve catalyst, wherein the Cu-SSZ-13 molecular sieve catalyst contains the SSZ-13 molecular sieve described in the second aspect of the present invention.

[0037] The fourth aspect of this invention provides the application of the SSZ-13 molecular sieve described in the second aspect or the Cu-SSZ-13 molecular sieve catalyst described in the third aspect of this invention in denitrification.

[0038] This invention employs a unique potassium ion-modified crystallization promoter to assist in the crystallization and synthesis of SSZ-13 molecular sieves. This can effectively inhibit the formation of impurities during the preparation of SSZ-13 molecular sieves and accelerate the establishment of the CHA framework structure. Therefore, the resulting zeolite has high crystallinity and low impurity content.

[0039] The present invention uses a potassium ion-modified crystallization accelerator, which not only avoids the introduction of phosphorus and the use of combined template agents in the prior art, but also has a simple preparation method for the crystallization accelerator with strong reproducibility, which significantly reduces the production difficulty of the entire SSZ-13 molecular sieve process, including wastewater treatment. On the other hand, the SSZ-13 molecular sieve produced is of stable and reliable quality and is very suitable for large-scale industrial production.

[0040] Furthermore, unlike most nanoscale agglomerated irregular crystals synthesized by existing technologies, the SSZ-13 molecular sieve prepared by the method described in this invention has micron-sized near-cubic-hexahedral crystals with a more stable structure and a low degree of agglomeration. It is also less susceptible to damage. Therefore, the catalyst obtained by modifying the SSZ-13 molecular sieve provided by this invention with active metal ion exchange exhibits excellent catalytic activity and good hydrothermal stability, and its service life is significantly increased even when used in harsh environments. Attached Figure Description

[0041] Figure 1 This is a scanning electron microscope image of the SSZ-13 molecular sieve prepared in Example 1;

[0042] Figure 2 This is a scanning electron microscope image of the SSZ-13 molecular sieve prepared in Example 6;

[0043] Figure 3 This is a scanning electron microscope image of the SSZ-13 molecular sieve prepared in Comparative Example 1;

[0044] Figure 4 This is a scanning electron microscope image of the SSZ-13 molecular sieve prepared in Comparative Example 2;

[0045] Figure 5 This is a scanning electron microscope image of the SSZ-13 molecular sieve prepared in Comparative Example 3. Detailed Implementation

[0046] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0047] The first aspect of this invention provides a method for preparing SSZ-13 molecular sieve, the method comprising the following steps:

[0048] 1) A first mixture containing a first aluminum source, a first silicon source, a potassium source, an organic template agent, and water is subjected to a first crystallization reaction to obtain a potassium-type accelerator;

[0049] 2) A mixture containing a second aluminum source, a second silicon source, an alkali source, an organic template agent, water, and the potassium-type accelerator is subjected to a second crystallization reaction to obtain a crystallized product.

[0050] In the potassium-type accelerator, the molar ratio of SiO2:Al2O3:K2O:R:H2O is 1:0.1-0.4:0.6-1.5:0.02-0.15:60-140, and R is an organic template agent.

[0051] According to a first aspect of the present invention, by using a potassium-type promoter with a specific composition to regulate and promote the formation and growth of SSZ-13 molecular sieve crystals, the formation of impurity crystals during the preparation of SSZ-13 molecular sieve can be effectively suppressed, the establishment of the CHA framework structure can be accelerated, resulting in a relatively high crystallinity of the obtained zeolite, and the prepared SSZ-13 molecular sieve crystals have a micron-sized near-cubic hexahedral structure, and the crystals are relatively dispersed and do not agglomerate in large quantities. Such a molecular sieve structure is stable and not easily damaged during use. The catalyst prepared by further modification with active metal ion exchange not only ensures catalytic activity during application, but also has excellent hydrothermal stability.

[0052] According to a preferred embodiment of the present invention, in the potassium-type promoter, the molar ratio of SiO2:Al2O3:K2O:R:H2O is 1:0.1-0.3:0.6-1.2:0.02-0.10:60-120, and R is an organic template agent (i.e., the molar ratio of the first silicon source (based on SiO2), the first aluminum source (based on Al2O3), the potassium source (based on K2O), the organic template agent R, and H2O is 1:0.1-0.3:0.6-1.2:0.02-0.10:60-120). This can further improve the structural stability of the molecular sieve, thereby further improving the hydrothermal stability of the prepared catalyst.

[0053] In this invention, the near-cubic-hexahedral structure refers to the three-dimensional structure of a single grain being hexahedral and approximately regular hexahedral, wherein the ratio of the length of the longest edge to the shortest edge is 1-1.3:1, and the included angle between any two faces is 80-100°.

[0054] The preparation method of the SSZ-13 molecular sieve described in this invention will be described in detail below.

[0055] First, the preparation method of the potassium-type accelerator in step 1) will be described.

[0056] In step 1) of the present invention, a potassium-type promoter is prepared by subjecting a first mixture containing a first aluminum source, a first silicon source, a potassium source, an organic template agent and water to a first crystallization reaction.

[0057] According to step 1) of the present invention, the first aluminum source can be any aluminum source commonly used in the art for molecular sieve preparation, such as aluminum hydroxide, aluminum sulfate, sodium aluminate, and alumina, without particular limitation. However, the inventors of the present invention have found in experiments that, compared with other aluminum sources, when the first aluminum source is aluminum hydroxide and / or aluminum sulfate, the morphology of the SSZ-13 molecular sieve prepared by the potassium-type promoter participating in the crystallization reaction in the subsequent step 2) is more controllable, the crystal structure is more regular, and the performance of the Cu-SSZ-13 molecular sieve catalyst further prepared therefrom is also more stable and reliable. Therefore, preferably, the first aluminum source is selected from aluminum hydroxide and / or aluminum sulfate.

[0058] According to step 1) of the present invention, the first silicon source can be any silicon source commonly used in the art for molecular sieve preparation, without particular limitation. For example, the first silicon source can be silica sol, fumed silica, water glass, sodium silicate, potassium silicate, and amorphous silica, etc. However, the inventors of the present invention found in the experimental process that, compared with other silicon sources, when the first silicon source is selected from silica sol, fumed silica, and amorphous silica, the morphology of the SSZ-13 molecular sieve prepared by the potassium-type promoter participating in the crystallization reaction in the subsequent step 2) is more controllable and the crystal structure is more regular. The Cu-SSZ-13 molecular sieve catalyst prepared thereby is also more stable and reliable. Therefore, preferably, the first silicon source is selected from silica sol, fumed silica, and amorphous silica.

[0059] According to step 1) of the present invention, the potassium source can be any potassium source that can be used in the art to synthesize molecular sieves, without particular limitation. In order to further improve the morphological regularity of the prepared SSZ-13 molecular sieve and reduce the formation of impurities, preferably, the potassium source is selected from one or more of potassium hydroxide, potassium sulfate, potassium chloride and potassium nitrate, and more preferably potassium hydroxide.

[0060] According to step 1) of the present invention, the organic template agent is not particularly limited and can be any organic template agent conventionally used in the art. For example, the organic template agent can be one or more of N,N,N-trimethyl-1-adamantyl ammonium hydroxide, benzyltrimethyl ammonium hydroxide, N,N,N-dimethylethylcyclohexyl ammonium bromide, tetraethylammonium hydroxide ion, tetramethylammonium hydroxide, and choline chloride. Preferably, it is N,N,N-trimethyl-1-adamantyl ammonium hydroxide. This ensures the formation of the CHA framework structure, further improves the crystallinity of the prepared SSZ-13 molecular sieve, and reduces the formation of impurities.

[0061] In this invention, when the organic template agent is N,N,N-trimethyl-1-adamantyl ammonium hydroxide, its aqueous solution can be used. The content of N,N,N-trimethyl-1-adamantyl ammonium hydroxide in the aqueous solution can be 10-60% by weight, for example, 25% by weight.

[0062] Furthermore, in steps 1) and 2) of the first aspect of the present invention, there are no special requirements for the water used; it can be any type of water used in the art for molecular sieve synthesis. Preferably, the water used in steps 1) and 2) is deionized water to avoid interference from other ions on crystallization.

[0063] According to step 1) of the present invention, the order in which the first aluminum source, the first silicon source, the potassium source, the organic template agent, and water are added to the first mixture is not particularly limited, as long as the above components can be mixed to obtain the first mixture. For example, the first aluminum source, the first silicon source, the potassium source, and the organic template agent can be added to water to obtain the first mixture; or, the first aluminum source, the first silicon source, the potassium source, and the template agent can be respectively mixed with an appropriate amount of water in advance to prepare corresponding aqueous solutions, and then the respective aqueous solutions can be mixed to obtain the first mixture; or, the first aluminum source, the potassium source, the organic template agent, and water can be mixed, and then the first silicon source can be added to the resulting mixture to obtain the first mixture.

[0064] According to a preferred embodiment of the present invention, in step 1), when preparing the first mixture, the first aluminum source, potassium source, organic template agent and water are mixed and stirred thoroughly, and then the first silicon source is added to the resulting mixture. This ensures that all components in the obtained first mixture are thoroughly mixed, which is more conducive to preparing SSZ-13 molecular sieves with regular morphology, and the catalyst prepared thereby exhibits superior catalytic activity and hydrothermal stability.

[0065] More specifically, in step 1), the first aluminum source, potassium source, organic template agent, and water are mixed and stirred thoroughly until completely miscible, resulting in a colorless and transparent mixture. The temperature of the resulting mixture is then maintained at 15-30°C. Next, the first silicon source is added to the mixture at a flow rate of 0.005-0.015 mL / (min·g mixture) and stirred. After gelation occurs, stirring continues for 0.5-5 hours (while maintaining the slurry temperature at 15-30°C throughout). This prevents excessively high local concentrations of the silicon source, which could lead to uneven gel composition, effectively avoiding the formation of impurities and improving the crystallinity of the molecular sieve product.

[0066] According to a first aspect of the present invention, in step 1), a potassium-type promoter is prepared by subjecting a first mixture to a first crystallization reaction. The conditions for the first crystallization reaction are not particularly limited, as long as the crystallization of the first mixture is achieved. Preferably, the first crystallization reaction is a dynamic crystallization reaction, i.e., the first crystallization reaction is carried out under dynamic conditions. This allows the promoter crystallization process to maintain component homogeneity, generates more free molecular sieve multi-ring precursors, prevents excessive precursor development, and facilitates the promoter's participation in the subsequent crystallization reaction in step 2). The resulting SSZ-13 molecular sieve exhibits more controllable morphology and a more regular crystal structure, thus providing a more stable and reliable Cu-SSZ-13 molecular sieve catalyst.

[0067] In the first crystallization reaction, the dynamic conditions can be provided by a reactor equipped with a mechanical stirring device, or the first crystallization reaction can be carried out in a reactor capable of rotation. For example, a homogeneous reactor or a mechanically stirred reactor can be used, or other reactors conventional in the art capable of realizing dynamic material movement can be used. Those skilled in the art can make appropriate choices, and the present invention does not impose any particular limitations on this.

[0068] In this invention, the conditions for the first crystallization reaction may include: a temperature of 20-120°C, a time of 5-50 hours, and a rotation speed of 50-500 rpm.

[0069] Regarding the conditions of the first crystallization reaction, the inventors of this invention discovered during extensive experiments that by carrying out the first crystallization reaction in stages, the potassium-type promoter prepared can better regulate the subsequent crystal growth of SSZ-13 molecular sieve, resulting in crystals with more regular morphology and a higher degree of dispersion among them.

[0070] Therefore, in a preferred embodiment of the present invention, the conditions for the first crystallization reaction include: reacting at a speed of 100-300 rpm for 2-30 h at 30-90 °C, and then reacting at 90-150 °C for 0.2-10 h.

[0071] In a particularly preferred embodiment of the present invention, the conditions for the first crystallization reaction include: reacting at a rotation speed of 150-200 rpm and at 40-80°C for 5-30 h, followed by continuing the reaction at 90-120°C for 0.5-4 h.

[0072] By subjecting the first mixture to the first crystallization reaction described above, the potassium-type accelerator of the present invention can be prepared.

[0073] In this invention, the content of each component in the potassium-type accelerator is calculated by the amount of feed.

[0074] Next, in step 2), a mixture containing a second aluminum source, a second silicon source, an alkali source, an organic template agent, water, and the potassium-type promoter is subjected to a second crystallization reaction to obtain a crystallized product.

[0075] According to step 2) of the present invention, the second aluminum source can be any aluminum source conventional in the art, without particular limitation. Preferably, the second aluminum source is selected from one or more of aluminum hydroxide, aluminum sulfate, sodium aluminate, and aluminum oxide.

[0076] According to step 2) of the present invention, the second silicon source can be any silicon source commonly used in the art, without any particular limitation. Preferably, the second silicon source is selected from one or more of silica sol, silica, water glass, sodium silicate, potassium silicate, and amorphous silica.

[0077] According to step 2) of the present invention, the alkali source can be any of the various alkali sources commonly used in the art for synthesizing molecular sieves, without particular limitation. Preferably, the alkali source is selected from sodium hydroxide and / or potassium hydroxide.

[0078] According to step 2) of the present invention, the organic template agent is not particularly limited and can be any organic template agent conventionally used in the art. For example, the organic template agent can be one or more of N,N,N-trimethyl-1-adamantyl ammonium hydroxide, benzyltrimethyl ammonium hydroxide, N,N,N-dimethylethylcyclohexyl ammonium bromide, tetraethyl ammonium hydroxide, tetramethyl ammonium hydroxide, and choline chloride. Preferably, it is N,N,N-trimethyl-1-adamantyl ammonium hydroxide. This ensures the formation of the CHA framework structure, further improves the crystallinity of the prepared SSZ-13 molecular sieve, and reduces the formation of impurities.

[0079] According to a first aspect of the invention, preferably, the organic template agent in step 1) is the same type as the organic template agent in step 2).

[0080] According to step 2) of the present invention, the order in which the second aluminum source, the second silicon source, the alkali source, the organic template agent, water, and the potassium-type accelerator are added is not particularly limited. For example, the second aluminum source, the second silicon source, the alkali source, the organic template agent, and the potassium-type accelerator can be added to water to obtain a mixture; or, the second aluminum source, the second silicon source, the alkali source, and the template agent can be mixed with an appropriate amount of water in advance to prepare corresponding aqueous solutions, and then each aqueous solution can be mixed with the potassium-type accelerator to obtain a mixture; or, the second aluminum source, the alkali source, the organic template agent, and water can be mixed, the second silicon source can be added to the resulting mixture, and then the potassium-type accelerator can be added to obtain the mixture.

[0081] According to a preferred embodiment of the present invention, in step 2), a second mixture containing a second aluminum source, a second silicon source, an alkali source, an organic template agent and water is contacted with the potassium-type promoter to carry out the second crystallization reaction.

[0082] More preferably, in step 2), after mixing the second aluminum source, alkali source, organic template agent and water, a second silicon source is added to the resulting mixture, and then the potassium-type promoter obtained in step 1) is added. This ensures that the gel components formed by the second mixture are uniform and that the potassium-type promoter plays a better role, resulting in a molecular sieve with high crystallinity, few impurities and good stability.

[0083] More specifically, in step 2), the second aluminum source, alkali source, organic template agent and water are mixed and stirred thoroughly until completely miscible, and the mixture is colorless and transparent. Then, the temperature of the resulting mixture is maintained at 15-30°C. Next, the second silicon source is added to the mixture at a flow rate of 0.005-0.015 mL / (min·g mixture) and stirred. After gelation occurs, stirring is continued for 0.5-5 h to obtain a slurry (the temperature of the slurry is always maintained at 15-30°C). Then, the potassium-type accelerator obtained in step 1) is added to the slurry and stirred thoroughly (e.g., stirring for 10-120 min).

[0084] This ensures that all components in the resulting mixture are thoroughly mixed, which is more conducive to the potassium-type promoter controlling the crystal morphology of SSZ-13 molecular sieve, and the catalyst prepared in this way has better catalytic activity and hydrothermal stability.

[0085] According to the present invention, in step 2), the amounts of the second aluminum source, the second silicon source, the alkali source, the organic template agent, and water are not particularly limited and can be conventional choices for preparing SSZ-13 molecular sieves in the art. For example, in the present invention, the molar ratio of the second silicon source (based on SiO2), the second aluminum source (based on Al2O3), the alkali source (based on metal oxide), the organic template R, and H2O can be 1:0.02-0.17:0.05-0.5:0.01-0.15:5-90. Preferably, the molar ratio of the second silicon source (based on SiO2), the second aluminum source (based on Al2O3), the alkali source (based on metal oxide), the organic template R, and H2O can be 1:0.04-0.1:0.2-0.4:0.04-0.08:20-70; more preferably, the molar ratio of the second silicon source (based on SiO2), the second aluminum source (based on Al2O3), the alkali source (based on metal oxide), the organic template R, and H2O can be 1:0.04-0.08:0.2-0.4:0.04-0.05:30-40.

[0086] By limiting the amount of each component in step 2) within the above range, SSZ-13 molecular sieve with a suitable silicon-to-aluminum ratio, perfect crystal morphology, and excellent activity and stability can be obtained.

[0087] Furthermore, in this invention, the amount of the potassium-type promoter relative to the mixture of the second aluminum source, second silicon source, alkali source, organic template agent, and water in the second mixture (i.e., step 2) is not particularly limited. The amount of the potassium-type promoter can be appropriately determined according to the amount of the second mixture. For example, in step 2), the amount of the potassium-type promoter is 0.02-1% by weight of the second mixture, preferably 0.02-0.2% by weight, and more preferably 0.05-0.1% by weight. If the amount of the potassium-type promoter is lower than the above range, the ability to control subsequent crystallization is limited, making it difficult to obtain SSZ-13 molecular sieves with regular morphology, uniform size, and good dispersion. If the amount of the potassium-type promoter is higher than the above range, the size of the crystals will be reduced, resulting in smaller crystals and increased agglomeration between individual crystals, thereby affecting the catalytic activity and hydrothermal stability of the catalyst prepared subsequently.

[0088] Furthermore, the potassium-type accelerator and the second mixture are preferably thoroughly mixed under stirring. For example, they can be stirred for 10-60 minutes, preferably 10-20 minutes.

[0089] According to a first aspect of the present invention, in step 2), the conditions for the second crystallization reaction are not particularly limited, and crystallization conditions commonly used in the art for preparing SSZ-13 molecular sieves can be adopted. For example, in step 2), the conditions for the second crystallization reaction may include: a temperature of 100-220°C and a time of 5-144 h; preferably, the conditions for the second crystallization reaction include: a temperature of 120-180°C and a crystallization time of 24-96 h. This results in a higher crystallinity and a more uniform and regular morphology of the prepared SSZ-13 molecular sieve.

[0090] Furthermore, to promote the stable and rapid growth of SSZ-13 molecular sieve crystals, preferably, the second crystallization reaction is a static crystallization reaction, that is, the second crystallization reaction is carried out under static conditions. Here, the static crystallization reaction can be carried out in various reaction vessels commonly used in the art to achieve static crystallization, and the present invention does not particularly limit it.

[0091] Thus, the crystallized product is prepared through a second crystallization reaction.

[0092] To further prepare SSZ-13 molecular sieve, the method described in the first aspect of the present invention may further include the steps of solid-liquid separation, washing, drying and calcination of the crystallized product.

[0093] In this invention, the solid-liquid separation is not particularly limited and can be performed using various methods conventional in the art. In a preferred embodiment of this invention, the solid-liquid separation is performed using vacuum filtration or high-speed centrifugation. Specific operating methods are well known to those skilled in the art and will not be described in detail here.

[0094] In this invention, the washing method is not particularly limited, and conventional washing methods in the art can be used. Deionized water is preferred for washing.

[0095] In a preferred embodiment of the present invention, the washing is carried out until the pH of the washing solution is 7-9.

[0096] Furthermore, in this invention, the drying method can be carried out according to conventional drying methods in the art. For example, the drying conditions may include: a temperature of 50-150°C and a time of 8-24 hours; preferably, the drying conditions include: a temperature of 80-120°C and a time of 10-16 hours.

[0097] Furthermore, in this invention, the roasting method can be carried out according to conventional roasting methods in the art. For example, the roasting conditions may include: a temperature of 400-700℃ and a time of 2-10h; preferably, the roasting conditions include: a temperature of 450-600℃ and a time of 4-8h.

[0098] By drying and calcining under the above conditions, the organic template agent in the SSZ-13 molecular sieve cage can be completely eliminated, and the SSZ-13 molecular sieve skeleton structure can be kept intact, thereby improving the quality of the SSZ-13 molecular sieve.

[0099] According to the method described in the first aspect of the present invention, by employing a unique potassium ion-modified crystallization promoter to assist in the crystallization and synthesis of SSZ-13 molecular sieves, the formation of impurities during the preparation of SSZ-13 molecular sieves can be effectively suppressed, and the establishment of the CHA framework structure can be accelerated. The resulting zeolite has high crystallinity and low impurity content. Furthermore, the SSZ-13 molecular sieve prepared by the method of the present invention has micron-sized near-cubic-hexahedral crystals, with a more stable structure that is not easily damaged. Therefore, the catalyst obtained by modifying the SSZ-13 molecular sieve provided by the present invention after active metal ion exchange exhibits excellent catalytic activity and good hydrothermal stability, and its service life is significantly increased even when used in harsh environments.

[0100] A second aspect of the present invention provides an SSZ-13 molecular sieve, which is prepared by the method described in the first aspect of the present invention.

[0101] In this invention, the SSZ-13 molecular sieve has a near-hexahedral structure, and the size of the SSZ-13 molecular sieve is 0.5-2 μm, preferably 0.6-1.5 μm, and more preferably 0.8-1.2 μm.

[0102] According to a second aspect of the present invention, the silica-alumina molar ratio of the SSZ-13 molecular sieve can be 9-25:1; preferably 14-22:1. By controlling the silica-alumina ratio of the SSZ-13 molecular sieve within the above range, the molecular sieve can simultaneously possess high activity and framework stability.

[0103] In this invention, the silicon-to-aluminum ratio refers to the molar ratio of SiO2 to Al2O3.

[0104] During the experiment, the inventors of this invention discovered that, under the same silicon-to-aluminum ratio, the SSZ-13 molecular sieve with micron-sized dispersed near-cubic hexahedral grains provided by this invention has significantly better hydrothermal stability. Compared with most existing SSZ-13 molecular sieves with nano-sized agglomerated irregular grains, the SSZ-13 molecular sieve with the morphology described in this invention has both excellent hydrothermal stability and reactivity.

[0105] In this invention, the preparation method of SSZ-13 molecular sieve described in the second aspect is the same as that described in the first aspect of this invention, and will not be repeated here.

[0106] A third aspect of the present invention provides a Cu-SSZ-13 molecular sieve catalyst, wherein the Cu-SSZ-13 molecular sieve catalyst contains the SSZ-13 molecular sieve described in the second aspect of the present invention.

[0107] According to a third aspect of the present invention, the Cu-SSZ-13 molecular sieve catalyst contains the SSZ-13 molecular sieve described in the second aspect of the present invention, which has both excellent hydrothermal stability and catalytic activity, and can maintain efficient denitrification catalytic performance for a long time even under harsh treatment conditions.

[0108] According to a third aspect of the present invention, in the Cu-SSZ-13 molecular sieve catalyst, the content of SSZ-13 molecular sieve is 95-99% by weight, preferably 96-98.5% by weight; the content of Cu is 1-5% by weight, preferably 1.5-4% by weight. By controlling the content of SSZ-13 molecular sieve and the content of active metal Cu within the above ranges, the denitrification performance of the obtained Cu-SSZ-13 molecular sieve catalyst is more excellent.

[0109] In addition, regarding the preparation method of the Cu-SSZ-13 molecular sieve catalyst described in the third aspect of the present invention, apart from using the SSZ-13 molecular sieve described in this application as a raw material, the rest can be prepared according to the conventional Cu-SSZ-13 molecular sieve catalyst preparation methods in the art.

[0110] For example, conventional methods in the art, such as the two-stage exchange and two-stage calcination, can be used to prepare it. More specifically, for example, SSZ-13 molecular sieves can first undergo ammonium exchange and a first calcination to obtain hydrogen-form SSZ-13 molecular sieves, and then copper ion exchange and a second calcination can be performed to prepare Cu-SSZ-13 molecular sieve catalysts. Such preparation methods are well known to those skilled in the art and will not be described in detail here.

[0111] The fourth aspect of this invention provides the application of the SSZ-13 molecular sieve described in the second aspect or the Cu-SSZ-13 molecular sieve catalyst described in the third aspect of this invention in denitrification.

[0112] According to the present invention, denitrification using the SSZ-13 molecular sieve or Cu-SSZ-13 molecular sieve catalyst provided by the present invention not only has excellent denitrification performance, but also can be carried out in harsh hydrothermal environments, possessing both excellent hydrothermal stability and denitrification catalytic activity.

[0113] The present invention will be described in detail below through embodiments.

[0114] In the following embodiments, the analysis methods for each parameter are as follows:

[0115] The crystal form and crystallinity of SSZ-13 molecular sieve were tested using a Rigaku Smart Lab Se X-ray diffractometer (Japan).

[0116] The silica and alumina content of SSZ-13 molecular sieve was tested using a Perkin Elmer Avio 200 inductively coupled plasma atomic emission spectrometer.

[0117] The morphology of SSZ-13 molecular sieve was observed using a Thermo Fisher Scientific FEI Talos F200X scanning electron microscope.

[0118] Example 1

[0119] 1) Aluminum sulfate, potassium hydroxide, N,N,N-trimethyl-1-adamantyl ammonium hydroxide (TMAdaOH, 25% wt% aqueous solution) and deionized water were mixed and stirred until the mixture was colorless and transparent. Then, silica sol was added to it at a flow rate of 0.01 mL / (min·g mixture) and stirred. After gelation, stirring was continued for 1 h to obtain the first mixture. The amount of each component added was such that the molar ratio of SiO2:Al2O3:K2O:TMAdaOH:H2O in the first mixture was 1:0.15:0.9:0.06:90.

[0120] 2) The first mixture obtained in step 1) was subjected to a first crystallization reaction in a mechanically stirred tank at a stirring speed of 200 rpm. During the first crystallization reaction, the mixture was first reacted at 60°C for 7 hours, and then the temperature was raised to 100°C and the reaction was continued for 2 hours to obtain a potassium-type accelerator.

[0121] 3) Aluminum sulfate, sodium hydroxide, N,N,N-trimethyl-1-adamantyl ammonium hydroxide (TMAdaOH, 25% wt% aqueous solution) and deionized water were mixed and stirred until the mixture was colorless and transparent. Then, silica sol was added to it at a flow rate of 0.01 mL / (min·g mixture) and stirred. After gelation, stirring was continued for 1 h to obtain a second mixture. The amount of each component added was such that the molar ratio of SiO2:Al2O3:Na2O:TMAdaOH:H2O in the second mixture was 1:0.05:0.28:0.04:30.

[0122] 4) Add the potassium-type accelerator obtained in step 2) to the second mixture obtained in step 3). The amount of potassium-type accelerator is 0.1% by weight of the second mixture. After stirring and mixing for 15 minutes, a mixed slurry is obtained.

[0123] 5) The mixed slurry obtained in step 4) is subjected to a second crystallization reaction in a constant temperature static reactor at a reaction temperature of 155℃ for 48h to obtain a second crystallization product. Then, the reaction system is cooled to 25℃ by a cold water bath, and the second crystallization product is vacuum filtered to obtain a filter cake. The filter cake is washed with deionized water until the pH of the washing liquid is 8. The obtained solid material is then dried at 100℃ for 12h and calcined at 600℃ for 5h to obtain SSZ-13 molecular sieve S1.

[0124] The scanning electron microscope image of S1 is as follows: Figure 1 As shown, by Figure 1 It can be seen that the S1 grains have a near-hexahedral structure, with a grain size between 0.8 and 1.2 μm, and low agglomeration rate and good dispersion.

[0125] The crystal form, crystallinity, grain morphology, and silicon-aluminum ratio of S1 are shown in Table 1.

[0126] Example 2

[0127] The method is carried out according to Example 1, with the following difference:

[0128] In step 1), the amount of each component fed is such that the molar ratio of SiO2:Al2O3:K2O:TMAdaOH:H2O in the first mixture is 1:0.1:1.2:0.02:60;

[0129] In step 2), during the first crystallization reaction, the reaction is first carried out at 40°C for 30 hours, and then the temperature is raised to 90°C and the reaction continues for 4 hours.

[0130] In step 3), potassium hydroxide is used as the alkali source, and the amount of each component added is such that the molar ratio of SiO2:Al2O3:K2O:TMAdaOH:H2O in the second mixture is 1:0.07:0.35:0.04:30;

[0131] In step 4), the amount of potassium-type accelerator used is 0.05% by weight of the second mixture;

[0132] In step 5), the reaction temperature of the second crystallization reaction is 175℃ and the reaction time is 24h.

[0133] SSZ-13 molecular sieve S1 was obtained.

[0134] The scanning electron microscope (SEM) images of S2 are similar to those of S1. The SEM images of S2 show that the grains of S2 have a near-hexahedral structure, with grain sizes ranging from 0.8 to 1.2 μm, and exhibit low agglomeration and good dispersion.

[0135] The crystal form, crystallinity, grain morphology, and silicon-aluminum ratio of S2 are shown in Table 1.

[0136] Example 3

[0137] The method is carried out according to Example 1, with the following difference:

[0138] In step 1), the amount of each component fed is such that the molar ratio of SiO2:Al2O3:K2O:TMAdaOH:H2O in the first mixture is 1:0.3:0.6:0.10:120;

[0139] In step 2), during the first crystallization reaction, the reaction is first carried out at 80°C for 5 hours, and then the temperature is raised to 120°C and the reaction continues for 0.5 hours.

[0140] In step 3), potassium hydroxide is used as the alkali source, and the amount of each component added is such that the molar ratio of SiO2:Al2O3:K2O:TMAdaOH:H2O in the second mixture is 1:0.045:0.22:0.05:40;

[0141] In step 4), the amount of potassium-type accelerator used is 0.75% by weight of the second mixture;

[0142] In step 5), the reaction temperature of the second crystallization reaction is 140℃ and the reaction time is 96h.

[0143] SSZ-13 molecular sieve S3 was obtained.

[0144] The scanning electron microscope (SEM) images of S3 are similar to those of S1. The SEM images of S3 show that the grains of S3 have a near-hexahedral structure, with grain sizes ranging from 0.8 to 1.2 μm, and exhibit low agglomeration and good dispersion.

[0145] The crystal form, crystallinity, grain morphology, and silicon-aluminum ratio of S3 are shown in Table 1.

[0146] Example 4

[0147] The method is carried out according to Example 1, with the following difference:

[0148] In step 4), the amount of potassium-type accelerator used is 0.2% by weight of the second mixture;

[0149] SSZ-13 molecular sieve S4 was obtained.

[0150] The scanning electron microscope image of S4 shows that the grains of S4 have a near-cubic structure, with a grain size of about 0.5-0.8 μm. The grains have a low agglomeration rate and good dispersion.

[0151] The crystal form, crystallinity, grain morphology, and silicon-aluminum ratio of S4 are shown in Table 1.

[0152] Example 5

[0153] The method is carried out according to Example 1, with the following difference:

[0154] In step 1), the amount of each component fed is such that the molar ratio of SiO2:Al2O3:K2O:TMAdaOH:H2O in the first mixture is 1:0.4:1.5:0.15:140;

[0155] SSZ-13 molecular sieve S5 was obtained.

[0156] The scanning electron microscope image of S5 shows that the grains of S5 have a near-hexahedral structure, with a grain size between 0.6 and 1 μm, and low agglomeration rate and good dispersion.

[0157] The crystal form, crystallinity, grain morphology, and silicon-aluminum ratio of S5 are shown in Table 1.

[0158] Example 6

[0159] The method is carried out according to Example 1, with the following difference:

[0160] In step 2), during the first crystallization reaction, the reaction is first carried out at 90°C for 7 hours, and then the temperature is raised to 140°C and the reaction continues for 2 hours.

[0161] SSZ-13 molecular sieve S6 was obtained.

[0162] The scanning electron microscope image of S6 is shown below. Figure 2 As shown.

[0163] The scanning electron microscope images of S6 show that the grains of S6 have a near-hexahedral structure, with a grain size between 1 and 1.3 μm, and the grains have a low agglomeration rate and good dispersion.

[0164] The crystal form, crystallinity, grain morphology, and silica-alumina ratio of S6 are shown in Table 1.

[0165] Example 7

[0166] The method is carried out according to Example 1, with the following difference:

[0167] In step 2), the first crystallization reaction is carried out at 90°C for 9 hours.

[0168] SSZ-13 molecular sieve S7 was obtained.

[0169] The scanning electron microscope images of S7 show that the grains of S7 have a near-cubic structure, with a grain size between 0.8 and 1.1 μm, and low agglomeration rate and good dispersion.

[0170] The crystal form, crystallinity, grain morphology, and silicon-aluminum ratio of S7 are shown in Table 1.

[0171] Comparative Example 1

[0172] The method is carried out according to Example 1, with the following difference:

[0173] Skip steps 1-2) and proceed directly to step 3), and do not add potassium-type accelerator to the second mixture in step 4).

[0174] SSZ-13 molecular sieve D1 was obtained.

[0175] The scanning electron microscope image of D1 is as follows: Figure 3 As shown.

[0176] As can be seen from the scanning electron microscope image of D1, the grain structure of D1 is irregular, with a large number of grains agglomerated and stacked, resulting in poor dispersion.

[0177] The crystal form, crystallinity, grain morphology, and silica-alumina ratio of D1 are shown in Table 1.

[0178] Comparative Example 2

[0179] The method is carried out according to Example 1, with the following difference:

[0180] In step 1), sodium hydroxide is used instead of potassium hydroxide in equal molar amounts.

[0181] SSZ-13 molecular sieve D2 was obtained.

[0182] The scanning electron microscope image of D2 is as follows: Figure 4 As shown.

[0183] The scanning electron microscope images of D2 show that the grains of D2 are irregular in shape, with a grain size between 0.2 and 0.5 μm, and the grains have a high agglomeration rate and poor dispersibility.

[0184] The crystal form, crystallinity, grain morphology, and silica-alumina ratio of D2 are shown in Table 1.

[0185] Comparative Example 3

[0186] The method is carried out according to Example 1, with the following difference:

[0187] In step 1), the amount of each component fed is such that the molar ratio of SiO2:Al2O3:K2O:TMAdaOH:H2O in the first mixture is 1:0.5:0.4:0.20:150;

[0188] SSZ-13 molecular sieve D3 was obtained.

[0189] The scanning electron microscope image of D3 is shown below. Figure 5 As shown.

[0190] The scanning electron microscope images of D3 show that the grains of D3 are irregular in shape, with a grain size between 2 and 5 μm, and the grains have a high agglomeration rate and poor dispersibility.

[0191] The crystal form, crystallinity, grain morphology, and silica-alumina ratio of D3 are shown in Table 1.

[0192] Table 1

[0193] Molecular sieve number Crystal form Crystallinity Grain morphology Silicon-to-aluminum ratio S1 CHA 105.6％ Nearly hexahedral, well dispersed 20.3 S2 CHA 105.3％ Nearly hexahedral, well dispersed 14.9 S3 CHA 104.9％ Nearly hexahedral, well dispersed 21.8 S4 CHA 102.5％ Nearly hexahedral, well dispersed 20.1 S5 CHA 102.4％ Nearly hexahedral, well dispersed 19.4 S6 CHA 99.2％ Nearly hexahedral, well dispersed 20.2 S7 CHA 98.7％ Nearly hexahedral, well dispersed 20.4 D1 CHA, MOR 90.3％ Irregular, large-scale stacking 17.9 D2 CHA 93.3％ No rules, high reunion rate 21.4 D3 CHA 102.4％ Unregulated, large-scale reunions 19.4

[0194] As can be seen from the results in Table 1, the SSZ-13 molecular sieve prepared by the method provided in this invention has high crystallinity, all of which are CHA crystals, and the crystals have a near-cubic-hexahedral morphology with good dispersion between crystals.

[0195] Preparation Example

[0196] This preparation example illustrates the preparation of Cu-SSZ-13 molecular sieve catalysts.

[0197] The SSZ-13 molecular sieves prepared in the above examples and comparative examples were respectively prepared into corresponding Cu-SSZ-13 molecular sieve catalysts according to the following methods:

[0198] 1) Place 3.5g of SSZ-13 molecular sieve in 100mL of ammonium sulfate aqueous solution (ammonium sulfate concentration is 2.75mol / L) and perform ion exchange at 80℃ for 2h;

[0199] 2) Repeat step 1) 3 times. After the ion exchange product is thoroughly washed, it is dried at 80°C for 12 hours and then calcined in a muffle furnace at 550°C for 4 hours to obtain hydrogen-form SSZ-13 molecular sieve.

[0200] 3) Add 1.5g of the hydrogen-form SSZ-13 molecular sieve obtained in step 2) to 2.25mL of copper acetate aqueous solution (copper acetate concentration is 0.314mol / L), and perform copper ion exchange at 75℃ for 4h. Then, raise the temperature to 100℃, evaporate all the water, and transfer the remaining powder to a muffle furnace for calcination at 600℃ for 2h to obtain a Cu-SSZ-13 molecular sieve catalyst with a Cu content of 3% by weight.

[0201] The Cu-SSZ-13 molecular sieve catalysts prepared using the SSZ-13 molecular sieves obtained in Examples 1-7 and Comparative Examples 1-3 were named Cu-S1~Cu-S7 and Cu-D1~Cu-D3, respectively.

[0202] Test case

[0203] The following test examples are used to test the performance of catalysts Cu-S1 to Cu-S7 and Cu-D1 to Cu-D3.

[0204] Test Example 1 - Reactivity Test

[0205] The Cu-SSZ-13 molecular sieve catalyst prepared in the above preparation example was loaded into a fixed-bed denitrification reactor to test its ability to treat nitrogen-containing waste gas. Specifically,

[0206] The reaction temperature is 100-550℃, and the reaction gas is simulated vehicle exhaust gas (NO content 500ppm, NH3 500ppm, O2 10% by volume, H2O 5% by volume, balance N2), with a volume hourly space velocity of 360,000 h⁻¹. -1 Calculate the NO conversion rate (C) of each catalyst at 200℃ using the following formula. 200 ):

[0207]

[0208] Among them, [NO x ] inThis refers to the NO at the inlet of the fixed-bed denitrification reactor. x Content (ppm), [NO x ] out This refers to the NO at the outlet of a fixed-bed denitrification reactor. x Content (ppm), NO x It represents NO and NO2.

[0209] Test Example 2 - Hydrothermal Stability Test

[0210] The Cu-SSZ-13 molecular sieve catalyst was placed in flowing air with a water vapor content of 10% by volume and an air flow rate of 100 mL / min, and hydrothermally aged at 750℃ for 20 h.

[0211] Then, it was loaded into a fixed-bed denitrification reactor, and the conversion rate (AC) of NO at 200℃ for each Cu-SSZ-13 molecular sieve catalyst was calculated according to the method and formula described in Test Example 1. 200 ).

[0212] The test results for Test Example 1 and Test Example 2 are shown in Table 2.

[0213] Table 2

[0214] serial number Cu-S1 Cu-S2 Cu-S3 Cu-S4 Cu-S5 Cu-S6 Cu-S7 Cu-D1 Cu-D2 Cu-D3 [C 200 ]]> 100％ 100％ 100％ 98.8％ 99.7％ 98.8％ 97.9％ 90.1％ 94.2％ 95.2％ <![CDATA[AC 200 ]]> 100％ 100％ 100％ 98.4％ 98.2％ 98.8％ 97.7％ 85.9％ 89.9％ 90.3％

[0215] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for preparing SSZ-13 molecular sieve, characterized in that, The preparation method includes the following steps: 1) A first mixture containing a first aluminum source, a first silicon source, a potassium source, an organic template agent, and water is subjected to a first crystallization reaction to obtain a potassium-type accelerator; 2) A mixture containing a second aluminum source, a second silicon source, an alkali source, an organic template agent, water, and the potassium-type accelerator is subjected to a second crystallization reaction to obtain a crystallized product. In the potassium-type accelerator, the molar ratio of SiO2:Al2O3:K2O:R:H2O is 1:0.1-0.4:0.6-1.5:0.02-0.15:60-140, and R is an organic template agent.

2. The preparation method according to claim 1, wherein, In step 2), the second mixture containing the second aluminum source, the second silicon source, the alkali source, the organic template agent and water is brought into contact with the potassium-type promoter to carry out the second crystallization reaction; Preferably, in the potassium-type accelerator, the molar ratio of SiO2:Al2O3:K2O:R:H2O is 1:0.1-0.3:0.6-1.2:0.02-0.10:60-120, where R is an organic template agent; Preferably, in the second mixture, the molar ratio of the second silicon source (calculated as SiO2), the second aluminum source (calculated as Al2O3), the alkali source (calculated as metal oxide), the organic template R, and H2O is 1:0.02-0.17:0.05-0.5:0.01-0.15:5-90; more preferably, it is 1:0.04-0.08:0.2-0.4:0.04-0.05:30-40. Preferably, in step 2), the amount of the potassium-type accelerator is 0.02-1% by weight of the second mixture, more preferably 0.05-0.1% by weight.

3. The preparation method according to claim 1, wherein, In step 1), the first crystallization reaction is a dynamic crystallization reaction; Preferably, the conditions for the first crystallization reaction include: a temperature of 20-120°C, a time of 5-50 hours, and a rotation speed of 50-500 rpm. Preferably, the conditions for the first crystallization reaction include: reacting at a rotation speed of 100-300 rpm and at 30-90°C for 2-30 h, followed by reacting at 90-150°C for 0.2-10 h. More preferably, the conditions for the first crystallization reaction include: reacting at a rotation speed of 150-200 rpm and at 40-80°C for 5-30 h, followed by reacting at 90-120°C for 0.5-4 h.

4. The preparation method according to claim 1, wherein, In step 2), the conditions for the second crystallization reaction include: a temperature of 100-220℃ and a time of 5-144h; Preferably, the conditions for the second crystallization reaction include: a temperature of 120-180°C and a crystallization time of 24-96 hours; Preferably, the second crystallization reaction is a static crystallization reaction.

5. The preparation method according to any one of claims 1-4, wherein, The method further includes: The crystallized product obtained in step 2) is dried and calcined; Preferably, the drying conditions include: a temperature of 50-150°C and a time of 8-24 hours; Preferably, the calcination conditions include: a temperature of 400-700℃ and a time of 2-10h.

6. The preparation method according to any one of claims 1-4, wherein, The first aluminum source is selected from aluminum hydroxide and / or aluminum sulfate; Preferably, the first silicon source is selected from one or more of silica sol, silica, and amorphous silica; Preferably, the potassium source is selected from one or more of potassium hydroxide, potassium sulfate, potassium chloride, and potassium nitrate; Preferably, the organic template agent is selected from one or more of N,N,N-trimethyl-adamantyl ammonium hydroxide, benzyltrimethyl ammonium hydroxide, N,N,N-dimethylethylcyclohexyl ammonium bromide, tetraethyl ammonium hydroxide, tetramethyl ammonium hydroxide, and choline chloride; more preferably, it is N,N,N-trimethyl-adamantyl ammonium hydroxide. Preferably, the second aluminum source is selected from one or more of aluminum hydroxide, aluminum sulfate, sodium aluminate, and aluminum oxide; Preferably, the second silicon source is selected from one or more of silica sol, silica fume, water glass, sodium silicate, potassium silicate, and amorphous silica; Preferably, the alkali source is selected from sodium hydroxide and / or potassium hydroxide.

7. An SSZ-13 molecular sieve, characterized in that, The SSZ-13 molecular sieve is prepared by the method described in any one of claims 1-6.

8. The SSZ-13 molecular sieve according to claim 7, wherein, The SSZ-13 molecular sieve has a near-hexahedral structure, and the size of the SSZ-13 molecular sieve is 0.5-1.5 μm, preferably 0.8-1.2 μm; Preferably, the silica-alumina ratio of the SSZ-13 molecular sieve is 9-25:1; more preferably, it is 14-22:

1. Preferably, the crystallinity of the SSZ-13 molecular sieve is 98-106%; more preferably, it is 104-106%.

9. A Cu-SSZ-13 molecular sieve catalyst, characterized in that, The Cu-SSZ-13 molecular sieve catalyst contains the SSZ-13 molecular sieve as described in claim 7 or 8.

10. The application of the SSZ-13 molecular sieve of claim 7 or 8 or the Cu-SSZ-13 molecular sieve catalyst of claim 9 in denitrification.

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