One-step synthesis method and application of cu-ssz-13 molecular sieve

Abstract

The application relates to the technical field of catalyst preparation, and particularly discloses a one-step synthesis method and application of Cu-SSZ-13 molecular sieve, which comprises the following steps: S1: uniformly mixing inorganic alkali, deionized water, an aluminum source, a silicon source and a template agent to obtain solution A; S2: uniformly stirring the copper source into the solution A, and then placing the solution A in a hydrothermal reaction kettle to perform hydrothermal reaction, so as to obtain a copper-loaded silicoaluminate porous structure; and after washing and drying, performing calcination to decompose the template agent, thereby obtaining the Cu-SSZ-13 molecular sieve. The one-step synthesis method is simple in operation, significantly shortens the preparation period, is low in preparation cost, reduces pollution, is suitable for industrialized production, and the obtained Cu-SSZ-13 molecular sieve has excellent catalytic performance (especially low-temperature activity and hydrothermal stability), and has a wide application prospect in diesel vehicle nitrogen oxide tail gas purification.

Description

Technical Field

[0001] This invention relates to the field of catalyst preparation technology, and more specifically, to a one-step synthesis method and application of Cu-SSZ-13 molecular sieve. Background Technology

[0002] Cu-SSZ-13 molecular sieve is a copper-based aluminosilicate zeolite material with a CHA topology. Its unique eight-membered ring channel structure (pore size approximately 0.38 nm) and highly dispersed and stable activity endow it with excellent catalytic performance, particularly exhibiting outstanding low-temperature catalytic activity and hydrothermal stability in redox reactions. Therefore, Cu-SSZ-13 has broad application prospects in several important fields, including but not limited to: direct oxidation of methane to methanol, methanol-to-olefins (MTO), gas adsorption and separation, and especially as a selective catalytic reduction (SCR) catalyst for the removal of nitrogen oxides (NOx) from diesel vehicle exhaust, which has become a current research and application hotspot.

[0003] The traditional method for preparing Cu-SSZ-13 molecular sieves is the liquid-phase ion exchange method. This involves first synthesizing SSZ-13 molecular sieve crystals using a hydrothermal synthesis method, then obtaining H-type SSZ-13 molecular sieves through ammonium exchange, followed by copper ion exchange and calcination to obtain the Cu-SSZ-13 catalyst. While this method is mature and can yield catalysts with good performance, it suffers from drawbacks such as cumbersome steps and a long overall cycle. The reaction process includes SSZ-13 synthesis, ammonium exchange, copper exchange, washing and drying between each step, and final calcination, which typically takes 2-6 days to complete. This lengthy process significantly increases the preparation cost and greatly limits the large-scale industrial production and application of Cu-SSZ-13 molecular sieves.

[0004] To overcome the problem of long reaction cycles in liquid-phase ion exchange methods, existing technologies disclose a one-step hydrothermal synthesis method, which aims to directly introduce copper ions into the framework during the crystallization process of SSZ-13 molecular sieves, thereby simplifying the process and shortening the time. For example, Chinese Patent Publication No. CN119100415A discloses an economical and rapid method for synthesizing Cu-SSZ-13 molecular sieves, which involves mixing and aging copper salts, urea, aluminum source, alkali source, template agent, and silicon source, followed by hydrothermal crystallization. Although this method shortens the process, it has obvious drawbacks: (1) it requires the addition of urea as an auxiliary agent, increasing the cost of raw materials; (2) the copper salts used (such as copper sulfate, copper chloride, and copper nitrate) introduce sulfate ions ( ), chloride ions ( ), nitrate ( (3) The catalytic performance of the prepared Cu-SSZ-13 molecular sieve is relatively poor. Chinese Patent Publication No. CN112028086A discloses a nano Cu-SSZ-13 molecular sieve and its one-step synthesis method and application, which uses two specific template agents (the first template agent is such as adamantane hydrochloride, and the second template agent is such as choline phosphate) mixed with copper complex solution, silicon source and aluminum source for hydrothermal synthesis. Although the patent method shortens the process, it has the following problems: (1) Two different template agents must be used at the same time, which not only increases the complexity and cost of raw materials, but also makes the preparation process more complicated; (2) It also relies on the introduction of sulfate-containing ( ), chloride ions ( ), nitrate ( (3) The catalytic performance of the prepared Cu-SSZ-13 molecular sieve is relatively poor.

[0005] In summary, existing Cu-SSZ-13 molecular sieve preparation technologies generally suffer from drawbacks such as long preparation cycles, high preparation costs, poor environmental friendliness, and the inability of the final product's catalytic performance (e.g., low-temperature activity, hydrothermal stability) to meet stringent application requirements. Based on the above, this invention proposes a one-step synthesis method for Cu-SSZ-13 molecular sieves and its applications. Summary of the Invention

[0006] To address the shortcomings of existing Cu-SSZ-13 molecular sieve preparation technologies, such as long preparation cycles, high preparation costs, poor environmental friendliness, and poor product performance, this invention provides a one-step synthesis method and application for Cu-SSZ-13 molecular sieves.

[0007] To achieve the above objectives, the present invention is implemented through the following technical solution: A one-step synthesis method for Cu-SSZ-13 molecular sieve includes the following steps: S1: Mix the inorganic alkali, deionized water, aluminum source, silicon source, and template agent evenly to obtain solution A; S2: Add copper source to solution A and stir until homogeneous. Then place the solution in a hydrothermal reactor for hydrothermal reaction to obtain a copper-loaded aluminosilicate porous structure. After washing and drying, calcine the structure to decompose the template agent and obtain Cu-SSZ-13 molecular sieve.

[0008] Preferably, sodium hydroxide is used in step S1.

[0009] Preferably, the aluminum source in step S1 is at least one of sodium aluminate, sodium tetrahydroxyaluminate, potassium aluminate, boehmite, boehmite, alumina, bauxite, and alunite.

[0010] Preferably, the silicon source in step S1 is at least one of silica sol, fumed silica, and tetraethyl orthosilicate.

[0011] Preferably, in step S1, the molar ratio of silicon in the silicon source to aluminum in the aluminum source is 5-50:1.

[0012] Preferably, in step S1, the molar ratio of silicon in the silicon source to aluminum in the aluminum source is 15-35:1.

[0013] Preferably, the template agent in step S1 is at least one of N,N,N-trimethyl-1-adamantane-ammonium hydroxide, benzyltrimethylammonium hydroxide, tetraethylammonium hydroxide, and Cu-tetraethylenepentamine.

[0014] Preferably, in step S1, the ratio of the amount of template agent to the amount of silicon in the silicon source is 0.05-2:1.

[0015] Preferably, in step S2, the copper source is a salt of monovalent copper ions.

[0016] Preferably, in step S2, the copper source is a mixture of salts of monovalent copper ions and salts of divalent copper ions.

[0017] Preferably, the copper source in step S2 is cuprous chloride or cuprous bromide.

[0018] Preferably, the copper source in step S2 is a mixture of cuprous chloride and copper chloride.

[0019] Preferably, the copper source in step S2 is a mixture of cuprous chloride and copper sulfate.

[0020] Preferably, the copper source in step S2 is a mixture of cuprous chloride and copper nitrate.

[0021] Preferably, the temperature of the hydrothermal reaction in step S2 is 120℃-200℃, and the time is 12h-240h.

[0022] Preferably, the calcination temperature in step S2 is 450℃-650℃, and the time is 4h-6h.

[0023] Preferably, the molar ratio of copper in the copper source to silicon in the silicon source is 0.01-1:1.

[0024] Preferably, the molar ratio of copper in the copper source to silicon in the silicon source is 0.2-0.5:1.

[0025] Application of Cu-SSZ-13 molecular sieve as a selective catalytic reduction catalyst for nitrogen oxides in diesel vehicle exhaust.

[0026] Preferably, the temperature of the catalytic reduction is 150℃-500℃.

[0027] Preferably, the temperature of the catalytic reduction is 160℃-250℃.

[0028] In summary, the present invention has the following beneficial effects: The present invention provides a one-step synthesis method for Cu-SSZ-13 molecular sieves, which is simple to operate, significantly shortens the preparation cycle, and has low preparation cost. The synthesis process minimizes or eliminates the introduction of harmful anions, making it environmentally friendly and suitable for industrial production. The resulting Cu-SSZ-13 molecular sieve has excellent catalytic performance (especially low-temperature activity and hydrothermal stability), which can meet the needs of large-scale industrial production and high-end applications.

[0029] The Cu-SSZ-13 molecular sieve of this invention exhibits strong catalytic activity, high catalytic efficiency, strong hydrothermal stability and resistance to sulfur poisoning, and possesses a wide temperature window ranging from 160℃ to 500℃. Conversion rate of 92% or higher, T 90 The temperature window width can reach 340℃; within the range of 200℃-450℃, With a conversion rate as high as 99%, it has broad application prospects in the purification of nitrogen oxide exhaust gas from diesel vehicles. Attached Figure Description

[0030] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the embodiments of the invention to explain the invention and do not constitute a limitation thereof.

[0031] Figure 1 This is the XRD pattern of the Cu-SSZ-13 molecular sieve sample prepared in Example 1.

[0032] Figure 2 This is the XRD pattern of the Cu-SSZ-13 molecular sieve sample prepared in Comparative Example 1.

[0033] Figure 3 This is a scanning electron microscope image of the Cu-SSZ-13 molecular sieve sample prepared in Example 1. Detailed Implementation

[0034] The technical solution of the present invention will be further described in detail below with reference to specific embodiments. It should be understood that the following embodiments are merely illustrative and explanatory of the present invention, and should not be construed as limiting the scope of protection of the present invention. All technologies implemented based on the above content of the present invention are covered within the scope of protection intended by the present invention.

[0035] Examples 1-3 and Comparative Example 1 provide a one-step synthesis method for Cu-SSZ-13 molecular sieves. Example 1 A one-step synthesis method for Cu-SSZ-13 molecular sieve includes the following steps: S1: In a three-necked flask, add 4g of sodium hydroxide and 60g of deionized water, stir to dissolve, then add 3g of sodium aluminate, stir at 100r / min for 30min, and then add 30g of silica sol. (Content 40%), then add 48g of 25% N,N,N-trimethyl-1-adamantane ammonium hydroxide aqueous solution, and continue to stir thoroughly for 30min to obtain solution A; S2: Under rapid stirring at 800 r / min, 2.97 g of solid cuprous chloride (CuCl) was added to solution A, the temperature was raised to 50℃, and the mixture was stirred for 3 h. The material was then poured into a high-pressure reactor, sealed, and heated to 160℃ for hydrothermal reaction for 24 h. The material was then removed, allowed to stand, filtered, and the filter cake was washed with deionized water until neutral. The washed filter cake was dehydrated and dried, then placed in a muffle furnace and calcined at 550℃ for 5 h. After washing with water, it was dried at 150℃ for 12 h to obtain the Cu-SSZ-13 molecular sieve catalyst.

[0036] Example 2 A one-step synthesis method for Cu-SSZ-13 molecular sieve includes the following steps: S1: In a three-necked flask, add 4g of sodium hydroxide and 60g of deionized water, stir to dissolve, then add 3g of sodium aluminate, stir at 100r / min for 30min, and then add 30g of silica sol. (Content 40%), then add 48g of 25% N,N,N-trimethyl-1-adamantane ammonium hydroxide aqueous solution, and continue to stir thoroughly for 30min to obtain solution A; S2: Under rapid stirring at 800 r / min, 4.0 g of solid cuprous bromide (CuBr) was added to solution A, the temperature was raised to 50℃, and the mixture was stirred for 3 h. The material was then poured into a high-pressure reactor, sealed, and heated to 160℃ for hydrothermal reaction for 24 h. The material was then removed, allowed to stand, filtered, and the filter cake was washed with deionized water until neutral. The washed filter cake was dehydrated and dried, then placed in a muffle furnace and calcined at 550℃ for 5 h. After washing with water, it was dried at 150℃ for 12 h to obtain the Cu-SSZ-13 molecular sieve catalyst.

[0037] Example 3 A one-step synthesis method for Cu-SSZ-13 molecular sieve includes the following steps: S1: In a three-necked flask, add 4g of sodium hydroxide and 60g of deionized water, stir to dissolve, then add 3g of sodium aluminate, stir at 100r / min for 30min, and then add 30g of silica sol. (Content 40%), then add 48g of 25% N,N,N-trimethyl-1-adamantane ammonium hydroxide aqueous solution, and continue to stir thoroughly for 30min to obtain solution A; S2: Under rapid stirring at 800 r / min, add 1.0 g of copper sulfate pentahydrate to solution A, stir for 30 min, then add 2.3 g of solid cuprous chloride (CuCl), heat to 50℃, and stir for 3 h; then pour the material into an autoclave, seal and heat to 160℃, and perform hydrothermal reaction for 24 h. Remove the material, let it stand, filter, wash the filter cake with deionized water until neutral, remove water from the washed filter cake and dry it, then place it in a muffle furnace and calcine at 550℃ for 5 h, then wash with water and dry at 150℃ for 12 h to obtain Cu-SSZ-13 molecular sieve catalyst.

[0038] Comparative Example 1 Comparative Example 1 is the same as Example 1, except that solid cuprous chloride (CuCl) is replaced with an equal amount of copper chloride (CuCl). ).

[0039] Catalytic performance test: The NO content of the Cu-SSZ-13 molecular sieve catalysts prepared in Examples 1-3 and Comparative Example 1 of this invention was tested using a Synthetic Catalyst Activity Tester (SCAT) apparatus. X Conversion rate.

[0040] The specific test conditions were as follows: 500 ppm NO, 500 ppm NH3, 10% O2, 10% H2O, and balance N2; and a space velocity of 80,000 rpm. The conversion temperatures were successively 150℃, 160℃, 180℃, 200℃, 250℃, 350℃, 450℃, and 500℃. X The conversion rate test results are shown in Table 1 below.

[0041] Table 1: As shown in Table 1, the Cu-SSZ-13 molecular sieves prepared in Examples 1-3 of this invention exhibit excellent catalytic activity, NO X The conversion rate is high, and the overall performance is far superior to that of Comparative Example 1. The Cu-SSZ-13 molecular sieve prepared in Example 3 of this invention has a wide temperature window, with NO content significantly reduced within the range of 160℃-500℃. X Conversion rate of 92% or higher, T 90 The temperature window width can reach 340℃; within the range of 200℃-450℃, NO X With a conversion rate as high as 99%, it has broad application prospects in the purification of nitrogen oxide exhaust gas from diesel vehicles.

[0042] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details of the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention. Furthermore, various different embodiments of the present invention can be arbitrarily combined, as long as they do not violate the spirit of the present invention, they should also be considered as the content disclosed by the present invention.

Claims

1. A one-step synthesis method for Cu-SSZ-13 molecular sieve, characterized in that, Includes the following steps: S1: Mix the inorganic alkali, deionized water, aluminum source, silicon source, and template agent evenly to obtain solution A; S2: Add copper source to solution A and stir evenly. Then place it in a hydrothermal reactor for hydrothermal reaction to obtain a copper-loaded aluminosilicate porous structure. After washing and drying, calcine to decompose the template agent and obtain Cu-SSZ-13 molecular sieve. In step S1, the template agent is at least one of N,N,N-trimethyl-1-adamantane-ammonium hydroxide, benzyltrimethylammonium hydroxide, tetraethylammonium hydroxide, and Cu-tetraethylenepentamine. In step S2, the copper source is a salt of monovalent copper ions, or a mixture of salts of monovalent copper ions and salts of divalent copper ions. The molar ratio of copper in the copper source to silicon in the silicon source is 0.01-1:

1.

2. The one-step synthesis method of Cu-SSZ-13 molecular sieve according to claim 1, characterized in that, In step S1, the aluminum source is at least one of sodium aluminate, sodium tetrahydroxyaluminate, potassium aluminate, boehmite, boehmite, alumina, bauxite, and alunite.

3. The one-step synthesis method of Cu-SSZ-13 molecular sieve according to claim 1, characterized in that, In step S1, the silicon source is at least one of silica sol, fumed silica, and tetraethyl orthosilicate.

4. The one-step synthesis method of Cu-SSZ-13 molecular sieve according to claim 1, characterized in that, In step S1, the molar ratio of silicon in the silicon source to aluminum in the aluminum source is 5-50:

1.

5. The one-step synthesis method of Cu-SSZ-13 molecular sieve according to claim 1, characterized in that, In step S1, the ratio of the amount of template agent to the amount of silicon in the silicon source is 0.05-2:1.

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