Preparation method of SCR catalyst raw powder Cu-SSZ-13 molecular sieve
By using the complex formed by tetraethylene pentamine and copper ions as template agents, Cu-SSZ-13 molecular sieve is directly synthesized, which solves the problem of insufficient low-temperature activity and hydrothermal stability of the catalyst, and achieves cost reduction and simplified preparation process. Effect.
Patent Information
- Application Number
- CN202411567603.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-05
- Publication Date
- 2025-02-14
AI Technical Summary
In the prior art, the low-temperature activity and hydrothermal aging resistance of the Cu-SSZ-13 catalyst are insufficient, and the traditional preparation method is costly.
The relatively cheap tetraethylene pentamine and copper ions form complex as the template agent, and the Cu-SSZ-13 molecular sieve is directly synthesized under the promotion of a certain proportion of seed crystals.
The low-temperature activity and hydrothermal stability of the catalyst are improved, the preparation cost is reduced, and the preparation process is simplified.
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Figure CN119425779A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of catalyst production, in particular to a method for preparing SCR catalyst raw powder Cu-SSZ-13 molecular sieve. Background Art
[0002] Cu-SSZ-13 is a material that loads copper metal onto SSZ-13 molecular sieve. It selectively catalyzes redox reactions (elimination of nitrogen oxides NO with NH3 as a reducing agent). x It has very good catalytic performance in the polluted NH3-SCR reaction), especially excellent low-temperature catalytic activity and hydrothermal stability.
[0003] The traditional method of loading metallic copper into SSZ-13 molecular sieve is liquid phase ion exchange method, which uses expensive templates and has high synthesis cost. In addition, there are solid-state ion exchange method, microwave radiation synthesis method, and in-situ hydrothermal synthesis method. Among them, the product obtained by in-situ hydrothermal synthesis method has better dispersibility of Cu, which significantly improves the economic efficiency of preparation. However, the Cu-SSZ-13 synthesized directly by conventional copper-ammonia complex as template has low silicon-aluminum ratio, and its low-temperature activity and anti-hydrothermal aging ability need to be further improved.
[0004] Therefore, there is an urgent need for a method for preparing SCR catalyst raw powder Cu-SSZ-13 molecular sieve to solve the above technical problems. Summary of the invention
[0005] The object of the present invention is to provide a method for preparing SCR catalyst raw powder Cu-SSZ-13 molecular sieve in view of the shortcomings of the prior art. The method adopts a relatively cheap tetraethylenepentamine and copper ion to form a complex as a template agent, and directly synthesizes the Cu-SSZ-13 molecular sieve under the promotion of a certain proportion of seed crystals.
[0006] To achieve the above object, the present invention is implemented according to the following technical solutions:
[0007] The method for preparing the SCR catalyst raw powder Cu-SSZ-13 molecular sieve comprises the following steps:
[0008] S1, mixing a silicon source, an aluminum source, an alkali source, a template agent, and water and crystallizing the mixture to prepare a seed crystal;
[0009] S2, mixing a silicon source, an aluminum source, an alkali source, a copper-ammonia complex, and water to obtain a mixture;
[0010] S3, mixing the mixture with seed crystals to obtain slurry, and then subjecting the slurry to crystallization and post-treatment to obtain SCR catalyst raw powder Cu-SSZ-13 molecular sieve.
[0011] Preferably, in step S1, the molar ratio of silicon source, aluminum source, alkali source, template agent and water is (9-14):1:(1-3):(2-5):(260-360);
[0012] The silicon source, aluminum source, alkali source, template agent and water are mixed evenly, stirred for 6 to 8 hours, and crystallized at 140 to 170° C. for 48 to 72 hours.
[0013] Further preferably, in step S1, the molar ratio of the silicon source, the aluminum source, the alkali source, the template and water is (9-12):1:(1-2):(2-4):(300-350).
[0014] The crystallization time of the seed crystal of the present invention is 48 to 72 hours, which is short, significantly saving time cost and increasing yield. Moreover, only a small amount of N, N, N-trimethyl-1-adamantane-ammonium hydroxide is used in the preparation of the seed crystal, and expensive N, N, N-trimethyl-1-adamantane-ammonium hydroxide is not needed in the subsequent preparation, further saving production cost.
[0015] Preferably, in step S2, the molar ratio of the silicon source, the aluminum source, the alkali source, the copper-ammonia complex and water is (3-6):1:(4-7):(1-3):(90-120).
[0016] Further preferably, in step S2, the molar ratio of the silicon source, the aluminum source, the alkali source, the copper-ammonia complex and water is (4-6):1:(4-6):(1-3):(90-110).
[0017] Preferably, in step S3, the amount of seed crystals added is 5-10% of the mass of the mixture; the slurry is heated to 130-170° C. (crystallization temperature) and crystallized under self-increasing pressure for 24-72 hours (crystallization time).
[0018] More preferably, the slurry is heated to 140-170°C.
[0019] Still further preferably, in step S3, the amount of seed crystal added is 5-8% of the mass of the mixture; the crystallization temperature is 150-160° C., and the crystallization time is 48-72 h.
[0020] Preferably, in step S1 and step S2, the silicon source is at least one of silica sol, sodium silicate, diatomaceous earth, and white carbon black; the aluminum source is at least one of pseudo-boehmite, alumina, sodium aluminate, and aluminum isopropoxide; and the alkali source is at least one of potassium hydroxide and sodium hydroxide.
[0021] Further preferably, in step S1 and step S2, the silicon source is at least one of silica sol and sodium silicate; the aluminum source is at least one of pseudo-boehmite and sodium aluminate; and the alkali source is at least one of potassium hydroxide and sodium hydroxide.
[0022] Specifically, the molar amount of silica sol is calculated based on SiO2 in the silica sol; the molar amount of pseudo-boehmite is calculated based on Al2O3 in the pseudo-boehmite.
[0023] Preferably, in step S1, the template is N,N,N-trimethyl-1-adamantane-ammonium hydroxide;
[0024] In the step S2, the copper-ammine complex is at least one of a tetraethylenepentamine complex of copper nitrate, a tetraethylenepentamine complex of copper sulfate, and a tetraethylenepentamine complex of copper acetate.
[0025] More preferably, the copper-ammine complex is at least one of a tetraethylenepentamine complex of copper sulfate and a tetraethylenepentamine complex of copper acetate.
[0026] Specifically, the molar amount of the copper-ammonia complex is based on the Cu in the copper-ammonia complex. In the copper-ammonia complex, the molar ratio of Cu to tetraethylenepentamine is 1:1 to 1.5.
[0027] Preferably, in step S3, the post-treatment process includes filtration, washing, drying, ammonium exchange and roasting.
[0028] Preferably, in step S3, the ammonium exchange conditions are: using an ammonium chloride solution for exchange at 85-90° C. for 3-6 hours.
[0029] Specifically, the concentration of the ammonium chloride solution used is 1 mol / L, and the mass ratio of the solid for ammonium exchange to the ammonium chloride solution is 1:10.
[0030] Preferably, in step S3, the calcination temperature is 550-580° C., and the calcination time is 4-6 hours.
[0031] Beneficial effects:
[0032] The preparation method of the present invention is simple. Under the promotion of the seed crystal, the reaction system rapidly nucleates, the nucleation period is shortened, the crystallization rate becomes faster, the cost of the prepared catalyst raw powder is low, the silicon-aluminum ratio is appropriate, and the copper species is added in situ by using a copper-ammonia complex, so that the copper dispersion is high and the hydrothermal stability is high, and the catalyst can be directly applied to the NH3-SCR reaction. BRIEF DESCRIPTION OF THE DRAWINGS
[0033] Figure 1 XRD spectra of the Cu-SSZ-13 molecular sieves prepared in Example 1 (B) and Comparative Example 1 (A);
[0034] Figure 2 This is a comparison chart of the NH3-SCR reaction results of the Cu-SSZ-13 molecular sieve prepared in Example 1 and Comparative Example 1. DETAILED DESCRIPTION
[0035] The present invention is further described below with reference to specific embodiments. The illustrative embodiments and descriptions of the present invention are used to explain the present invention but are not intended to limit the present invention.
[0036] All raw materials of the present invention have no particular limitation on their sources, and can be purchased from the market or prepared according to conventional methods known to those skilled in the art.
[0037] There is no particular limitation on the purity of all raw materials in the present invention, and the present invention preferably adopts the conventional purity used in the art.
[0038] The devices used in the present invention are not particularly limited and can be any of the commonly used devices in the art.
[0039] Example 1
[0040] The method for preparing the SCR catalyst raw powder Cu-SSZ-13 molecular sieve comprises the following steps:
[0041] (1) 1.8 g of sodium hydroxide, 3.6 g of sodium aluminate (NaAlO2) and 90 g of N,N,N-trimethyl-1-adamantane-ammonium hydroxide (25% aqueous solution) were added to 240 g of water, and after stirring evenly, 90 g of silica sol with a solid content of 30 wt% (the amount of silica sol used was calculated based on the SiO2 contained therein) was added. After stirring for 8 h under sealing, the temperature was raised to 160° C. and crystallized for 72 h to obtain 425.4 g of SSZ-13 molecular sieve seed crystals.
[0042] (2) Add 480g of copper sulfate pentahydrate and 480g of tetraethylenepentamine to 2900g of water to obtain a copper-ammonia complex, then add 310g of sodium hydroxide and 140g of sodium aluminate, then add 1500g of silica sol with a solid content of 30wt% and all the seeds prepared in the above step (1), stir for 6h, and then heat to 150°C for crystallization for 72h. After the product is filtered, washed and dried, the dry powder is exchanged with 1M ammonium chloride solution at a mass ratio of 1:10 at 85°C for 4h, and then dried at 110°C and calcined at 550°C for 6h to obtain Cu-SSZ-13 molecular sieve.
[0043] Example 2
[0044] The method for preparing the SCR catalyst raw powder Cu-SSZ-13 molecular sieve comprises the following steps:
[0045] (1) 2.2 g of sodium hydroxide, 3.4 g of sodium aluminate and 100 g of N,N,N-trimethyl-1-adamantane-ammonium hydroxide (25% aqueous solution) were added to 250 g of water, and after stirring evenly, 98 g of silica sol with a solid content of 30 wt% was added. After stirring for 7 h under sealing, the temperature was raised to 170° C. and crystallized for 70 h to obtain 453.6 g of SSZ-13 molecular sieve seed crystals.
[0046] (2) Add 390g of copper acetate monohydrate and 460g of tetraethylenepentamine to 2800g of water to obtain a copper-ammonia complex, then add 320g of sodium hydroxide and 120g of sodium aluminate, then add 1600g of silica sol with a solid content of 30wt% and all the seed crystals prepared in the above step (1), stir for 7h, then heat to 150°C for crystallization for 48h. After filtering, washing and drying the product, take the dry powder and 1M ammonium chloride solution in a mass ratio of 1:10 and exchange at 85°C for 6h, then dry at 110°C and calcine at 580°C for 4h to obtain Cu-SSZ-13 molecular sieve.
[0047] Example 3
[0048] The method for preparing the SCR catalyst raw powder Cu-SSZ-13 molecular sieve comprises the following steps:
[0049] (1) Add 2.0 g of sodium hydroxide, 3.1 g of sodium aluminate and 100 g of N,N,N-trimethyl-1-adamantane-ammonium hydroxide (25% aqueous solution) to 230 g of water, stir evenly, add 90 g of silica sol with a solid content of 30%, stir for 8 h under sealing, then heat to 170° C. and crystallize for 72 h to obtain 425.1 g of SSZ-13 molecular sieve seed crystals.
[0050] (2) Add 460g of copper sulfate pentahydrate and 460g of tetraethylenepentamine to 3100g of water to obtain a copper-ammonia complex, then add 320g of sodium hydroxide and 240g of pseudo-boehmite containing 67wt% of aluminum oxide, then add 1500g of silica sol with a solid content of 30wt% and all the seeds prepared in the above step (1), stir for 8h, then heat to 160°C for crystallization for 60h. After filtering, washing and drying the product, take the dry powder and 1M ammonium chloride solution in a mass ratio of 1:10 and exchange at 90°C for 3h, then dry at 110°C and calcine at 560°C for 5h to obtain Cu-SSZ-13 molecular sieve.
[0051] Comparative Example 1
[0052] Add 30 g of sodium hydroxide and 1500 g of N,N,N-trimethyl-1-adamantane-ammonium hydroxide (25% aqueous solution) to 3800 mL of water, stir evenly, add 50 g of sodium aluminate, slowly add 1500 g of silica sol with a solid content of 30 wt%, stir for 6 h under sealing, then heat to 160 ° C and crystallize for 72 h to obtain SSZ-13 molecular sieve, exchange with 1 mol / L ammonium chloride solution to obtain H-SSZ-13 molecular sieve, and then exchange with a certain concentration of copper ion solution to obtain Cu-SSZ-13 molecular sieve.
[0053] test
[0054] The Cu-SSZ-13 molecular sieve obtained in Example 1 and Comparative Example 1 was tested under the following experimental conditions:
[0055] The activity of the SCR catalyst was evaluated in a fixed bed reactor at normal pressure. The catalyst dosage was 20 g. The reaction gas composition was: N2 balance gas, O2 content was 10%, NH3 content was 1%, NO content was 1%, CO2 content was 5%, H2O content was 8%, and the gas space velocity was 48000 h -1 .
[0056] like Figure 1 The XRD spectra of the Cu-SSZ-13 molecular sieves prepared in Example 1 (B) and Comparative Example 1 (A) are shown. The XRD spectra of the Cu-SSZ-13 molecular sieve prepared in Example 1 are represented by B, and the XRD spectra of the Cu-SSZ-13 molecular sieve prepared in Comparative Example 1 are represented by A.
[0057] like Figure 2 Shown is a comparison chart of the NH3-SCR reaction results of the Cu-SSZ-13 molecular sieves prepared in Example 1 and Comparative Example 1.
[0058] Depend on Figure 1 It can be seen that the prepared molecular sieve has typical characteristic diffraction peaks of SSZ-13 (2θ=9.5°, 14.0°, 16.1°, 17.7°, 20.8°, 25.0°, 30.9°), indicating that the target product with good crystal structure and high crystallinity has been prepared.
[0059] Depend on Figure 2 It can be seen that the Cu-SSZ-13 molecular sieve obtained in Example 1 is better than the Cu-SSZ-13 molecular sieve obtained in Comparative Example 1 in eliminating nitrogen oxides NO with NH3 as the reducing agent. x The polluted NH3-SCR reaction has a higher NO conversion rate in the entire temperature range.
[0060] The technical solution of the present invention is not limited to the above-mentioned specific embodiments. All technical variations made according to the technical solution of the present invention fall within the protection scope of the present invention.
Claims
1. The preparation method of SCR catalyst raw powder Cu-SSZ-13 molecular sieve is characterized by: The following steps are involved: S1, mixing a silicon source, an aluminum source, an alkali source, a template agent, and water and crystallizing the mixture to prepare a seed crystal; S2, mixing a silicon source, an aluminum source, an alkali source, a copper ammonia complex, and water to obtain a mixture; S3, mixing the mixture with seed crystals to obtain slurry, and then subjecting the slurry to crystallization and post-treatment to obtain SCR catalyst raw powder Cu-SSZ-13 molecular sieve.
2. The method for preparing the Cu-SSZ-13 molecular sieve as the SCR catalyst raw powder according to claim 1, characterized in that: In the step S1, the molar ratio of silicon source, aluminum source, alkali source, template agent and water is (9-14):1:(1-3):(2-5):(260-360); The silicon source, aluminum source, alkali source, template agent and water are mixed evenly, stirred for 6 to 8 hours, and crystallized at 140 to 170° C. for 48 to 72 hours.
3. The method for preparing the SCR catalyst raw powder Cu-SSZ-13 molecular sieve according to claim 1, characterized in that: In step S2, the molar ratio of the silicon source, the aluminum source, the alkali source, the copper-ammonia complex, and water is (3-6):1:(4-7):(1-3):(90-120).
4. The method for preparing the SCR catalyst raw powder Cu-SSZ-13 molecular sieve according to claim 1, characterized in that: In the step S3, the amount of seed crystal added is 5-10% of the mass of the mixture; the slurry is heated to 130-170° C. and crystallized under self-increasing pressure for 24-72 hours.
5. The method for preparing the SCR catalyst raw powder Cu-SSZ-13 molecular sieve according to claim 1, characterized in that: In step S1 and step S2, the silicon source is at least one of silica sol, sodium silicate, diatomaceous earth, and white carbon black; the aluminum source is at least one of pseudo-boehmite, alumina, sodium aluminate, and aluminum isopropoxide; and the alkali source is at least one of potassium hydroxide and sodium hydroxide.
6. The method for preparing the Cu-SSZ-13 molecular sieve as the SCR catalyst raw powder according to claim 1, characterized in that: In step S1, the template agent is N,N,N-trimethyl-1-adamantane-ammonium hydroxide; In the step S2, the copper-ammine complex is at least one of a tetraethylenepentamine complex of copper nitrate, a tetraethylenepentamine complex of copper sulfate, and a tetraethylenepentamine complex of copper acetate.
7. The method for preparing the SCR catalyst raw powder Cu-SSZ-13 molecular sieve according to claim 1, characterized in that: In step S3, the post-treatment process includes filtering, washing, drying, ammonium exchange, and roasting.
8. The method for preparing the Cu-SSZ-13 molecular sieve as the SCR catalyst raw powder according to claim 7, characterized in that: In step S3, the ammonium exchange conditions are: using an ammonium chloride solution for exchange at 85-90° C. for 3-6 hours.
9. The method for preparing the Cu-SSZ-13 molecular sieve as the SCR catalyst raw powder according to claim 7, characterized in that: In the step S3, the calcination temperature is 550-580° C. and the calcination time is 4-6 hours.