Cu-KFI molecular sieve as well as preparation method and application thereof
By optimizing the preparation process of Cu-KFI molecular sieve, one-step crystallization is carried out under alkaline conditions, and a one-step post-treatment method is adopted to solve the problems of complex processes, high cost and insufficient catalytic performance, and the Cu-KFI molecular sieve with high catalytic activity and hydrothermal stability is achieved.
Patent Information
- Application Number
- CN202510103368.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-22
- Publication Date
- 2025-05-02
AI Technical Summary
The existing Cu-KFI molecular sieve preparation process is complex, the production cost is high, and the catalytic activity and hydrothermal stability are insufficient, resulting in limited catalytic performance.
By optimizing the mixing process of silicon source, aluminum source, copper source and template agent, one-step crystallization is carried out under alkaline conditions, and a one-step post-treatment method is adopted, including the treatment of acid solution and/or ammonium salt solution, simplifying the process flow and improving the activity and stability of the catalyst.
The high catalytic activity, excellent hydrothermal stability and uniform dispersion of Cu-KFI molecular sieve are achieved, which simplifies the preparation process and reduces production costs.
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Figure CN119911925A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the field of molecular sieves, and more specifically, to a Cu-KFI molecular sieve and a preparation method and application thereof. Background Art
[0002] Nitrogen oxides (NO x ) is PM 2.5 One of the key precursors of ozone generation, controlling NO x Emissions are of vital importance. NH3 selective catalytic reduction technology (NH3-SCR) is the mainstream NO x Catalytic purification technology is widely used in NO removal from mobile and stationary sources due to its excellent performance. x removal, among which the Cu-KFI molecular sieve catalyst showed excellent NH3-SCR performance.
[0003] In the prior art, Cu-KFI molecular sieves are usually crystallized under alkaline conditions, and the final catalyst is obtained by performing a multi-step ion exchange reaction on the prepared Na-type molecular sieve. The above method generally has a multi-step post-processing process, such as ammonium exchange and copper exchange, which is complex and has a high production cost. At the same time, another method for preparing Cu-KFI molecular sieves is to directly mix the raw materials with the template and then crystallize them, but the activity of the Cu-KFI molecular sieve catalyst obtained by this process still has room for improvement, and the copper material is easy to agglomerate during the preparation process, and the dispersion is poor, resulting in the catalyst performance being limited.
[0004] Therefore, it is urgent to optimize the synthesis process of Cu-KFI molecular sieve to simplify the preparation process and improve the catalytic performance of the catalyst, so as to solve the current technical bottleneck. Summary of the invention
[0005] The purpose of the present invention is to provide a Cu-KFI molecular sieve and a preparation method and application thereof, optimize the synthesis process, and significantly improve the preparation yield, catalytic activity and hydrothermal stability of the Cu-KFI molecular sieve, so as to solve the technical problems existing in the above-mentioned background technology.
[0006] The technical solution of the present invention provides a method for preparing Cu-KFI molecular sieve, comprising the following steps:
[0007] S1: mixing a silicon source, an aluminum source, an alkali source, a first template and a first solvent for a first time to obtain a solution A; mixing a copper source, a second template and a second solvent for a second time to obtain a solution B;
[0008] S2: Mixing solution A and solution B for the third time, and performing a post-treatment on the system after reaction crystallization to obtain a Cu-KFI molecular sieve; wherein the reagent for the post-treatment comprises an acid solution and / or an ammonium salt solution.
[0009] In a preferred embodiment, the first template in S1 is a quaternary ammonium salt organic template; the second template includes one or more of tetraethylenepentamine, triethylenetetramine, diethylenetriamine or ammonia water.
[0010] In a preferred embodiment, the silicon source in S1 includes one or more of silica sol, sodium silicate, fumed silica, silica gel, Y molecular sieve, Beta molecular sieve or ZSM-5 molecular sieve; the aluminum source includes one or more of sodium aluminate, aluminum hydroxide, aluminum sulfate, pseudo-boehmite, Y molecular sieve, Beta molecular sieve or ZSM-5 molecular sieve; the alkali source includes sodium hydroxide and / or potassium hydroxide; the copper source includes one or more of copper sulfate, copper acetate, copper nitrate or copper chloride.
[0011] In a preferred embodiment, the molar ratio of the silicon source to the aluminum source in S1 is (1-50):1; the molar ratio of the silicon source to the alkali source is (1-30):1; the molar ratio of the silicon source to the first template is (1-30):1; the molar ratio of the copper source to the second template is (0.1-1.5):1; in the third mixing in S2, the molar ratio of the silicon source to the copper source is (1-1000):1.
[0012] In a preferred embodiment, the temperature ranges of the first mixing, the second mixing and the third mixing are 10-80°C respectively; the rotation speeds of the first mixing, the second mixing and the third mixing are 10-2000r / min; the time of the first mixing, the second mixing and the third mixing is 0.5-16h;
[0013] The reaction crystallization temperature in S2 is 120-200°C; the reaction crystallization time is 1-336h; the reaction crystallization is carried out under non-stirring closed conditions; the product after crystallization is cooled and separated.
[0014] In a preferred embodiment, the H+ concentration in the acid solution of the one-step post-treatment in S2 is 0.01-0.2 mol / L; the concentration of the ammonium salt solution is 0.01-0.5 mol / L; the treatment time is 1-24 h; the acid solution includes one or more of hydrochloric acid, nitric acid or sulfuric acid; the ammonium salt solution includes one or more of ammonium chloride, ammonium nitrate or ammonium sulfate.
[0015] In a preferred embodiment, the product after one-step post-treatment needs to be washed, dried and calcined to obtain a copper-based molecular sieve; and the drying temperature is 40-160°C; the calcination heating rate is 0.5-5°C / min; the calcination temperature is 500-900°C; and the calcination holding time is 5-10h.
[0016] The beneficial effects of the technical solution of the present invention are:
[0017] The Cu-KFI molecular sieve prepared by the invention has high catalytic activity, excellent hydrothermal stability and uniformly dispersed active copper species, and is particularly suitable for efficient conversion of nitrogen oxides.
[0018] By optimizing the mixing process of silicon source, aluminum source, copper source and template, as well as crystallizing under alkaline conditions and adopting one-step post-treatment, the method simplifies the process, reduces the complexity of multi-step ion exchange, and reduces production costs.
[0019] In general, the present invention optimizes the preparation and application of copper-based molecular sieves from the aspects of process and performance, and provides an efficient and economical solution. BRIEF DESCRIPTION OF THE DRAWINGS
[0020] Figure 1 The present invention is a graph showing the nitrogen oxide conversion rate before and after aging of the Cu-FKI molecular sieve prepared in Example 1-2 and Comparative Example 1-2 as a catalyst. DETAILED DESCRIPTION
[0021] The present invention is further described in detail below. The embodiments of the present invention are provided for the purpose of illustration and description, and are not intended to be exhaustive or to limit the present invention to the disclosed forms. Many modifications and variations will be apparent to those of ordinary skill in the art. The embodiments are selected and described to better illustrate the principles and practical applications of the present invention, and to enable those of ordinary skill in the art to understand the present invention and design various embodiments with various modifications suitable for specific uses.
[0022] The technical solution of the present invention provides a method for preparing a Cu-KFI molecular sieve, comprising the following steps:
[0023] S1: mixing a silicon source, an aluminum source, an alkali source, a first template and a first solvent for a first time to obtain a solution A; mixing a copper source, a second template and a second solvent for a second time to obtain a solution B;
[0024] S2: Mixing solution A and solution B for the third time, and performing a post-treatment on the system after reaction crystallization to obtain a Cu-KFI molecular sieve; wherein the reagent for the post-treatment comprises an acid solution and / or an ammonium salt solution.
[0025] The first template in S1 is a quaternary ammonium salt organic template, such as tetraethylammonium hydroxide; the second template includes one or more of tetraethylenepentamine, triethylenetetramine, diethylenetriamine or ammonia water.
[0026] The silicon source in S1 includes one or more of silica sol, sodium silicate, fumed silica, silica gel, Y molecular sieve, Beta molecular sieve or ZSM-5 molecular sieve; the aluminum source includes one or more of sodium aluminate, aluminum hydroxide, aluminum sulfate, pseudo-boehmite, Y molecular sieve, Beta molecular sieve or ZSM-5 molecular sieve; the alkali source includes sodium hydroxide and / or potassium hydroxide; the copper source includes one or more of copper sulfate, copper acetate, copper nitrate or copper chloride.
[0027] The molar ratio of the silicon source to the aluminum source in S1 is (1-50):1, preferably (5-40):1, and more preferably (10-20):1; preferably (5-15):1, and more preferably (5-10):1; the molar ratio of the silicon source to the first template is (1-30):1, preferably (5-15):1, and more preferably (5-10):1; the molar ratio of the copper source to the second template is (0.1-1.5):1, and preferably (0.5-1):1; in the third mixing in step (2), the molar ratio of the silicon source to the copper source is (1-1000):1, preferably (5-100):1, and more preferably (10-50):1.
[0028] The temperature ranges of the first mixing, the second mixing and the third mixing are 10-80°C respectively; the rotation speeds of the first mixing, the second mixing and the third mixing are 10-2000r / min; the time of the first mixing, the second mixing and the third mixing is 0.5-16h;
[0029] The reaction crystallization temperature in S2 is 120-200°C; the reaction crystallization time is 1-336h; the reaction crystallization is carried out under non-stirring closed conditions; the product after crystallization is cooled and separated.
[0030] The H+ concentration in the acid solution of the post-treatment step in S2 is 0.01-0.2 mol / L; the concentration of the ammonium salt solution is 0.01-0.5 mol / L; the treatment time is 1-24h; the acid solution includes one or more of hydrochloric acid, nitric acid or sulfuric acid; the ammonium salt solution includes one or more of ammonium chloride, ammonium nitrate or ammonium sulfate.
[0031] The product after the one-step post-treatment needs to be washed, dried and calcined to obtain the copper-based molecular sieve; the drying temperature is 40-160°C; the calcination heating rate is 0.5-5°C / min; the calcination temperature is 500-900°C; and the calcination insulation time is 5-10h.
[0032] Example 1
[0033] This embodiment provides a method for preparing a copper-based molecular sieve, which specifically comprises the following steps:
[0034] (I) 5 g of Y molecular sieve (wherein the molar ratio of silicon element to aluminum element is 12:1) and 0.6 g of sodium hydroxide and 15 mL of tetraethylammonium hydroxide solution (with a concentration of 0.75 M) were stirred and mixed in 20 mL of deionized water solution for 1 h at a temperature of 70° C. and a speed of 500 r / min to obtain solution A;
[0035] 0.8 g of anhydrous copper sulfate and 1.2 g of tetraethylene pentamine were stirred and mixed in 20 mL of deionized water solution for 1 hour at a stirring temperature of 70° C. and a stirring speed of 500 r / min to obtain solution B;
[0036] (II) stirring and mixing the solution A and solution B prepared in step (I) at a temperature of 60° C. and a rotation speed of 300 r / min for 2 hours to obtain a mixed system, placing the mixed system in a sealed reaction kettle, reacting and crystallizing at 140° C. for 96 hours, and after the reaction is completed, cooling to 50° C., and separating by sedimentation to obtain a solid phase product;
[0037] (III) The solid phase product obtained in step (II) is immersed in a 0.1 mol / L hydrochloric acid solution for a one-step post-treatment for 6 hours, the solid phase product after the one-step post-treatment is taken out, washed with deionized water for 4 times, dried at 70°C for 12 hours, and then heated to 600°C in a muffle furnace at a heating rate of 5°C / min for calcination for 6 hours to obtain a Cu-KFI molecular sieve.
[0038] Example 2
[0039] The difference between this embodiment and embodiment 1 is that in step (I), anhydrous cupric sulfate is 0.4 g and tetraethylene pentamine is 0.6 g. The rest is the same as embodiment 1.
[0040] Example 3
[0041] The difference between this embodiment and embodiment 1 is that the crystallization temperature in step (II) is 160 degrees and the crystallization time is 2 days. The rest is the same as embodiment 1.
[0042] Example 4
[0043] The difference between this embodiment and embodiment 1 is that the calcination temperature in step (III) is 700 degrees and the heating rate is 10 degrees / minute. The rest is the same as embodiment 1.
[0044] Comparative Example 1
[0045] The only difference between this embodiment and embodiment 1 is that no second template is added in step (I), and the rest is the same as embodiment 1.
[0046] Comparative Example 2
[0047] The only difference between this embodiment and embodiment 1 is that the calcination temperature in step (II) is 400 degrees, and the rest is the same as embodiment 1.
[0048] Comparative Example 3
[0049] The only difference between this embodiment and embodiment 1 is that the crystallization temperature in step (III) is 120 degrees, and the rest is the same as embodiment 1.
[0050] Performance Test:
[0051] (1) Yield test: Yield = mass of sample after drying and calcination / (mass of SiO2+Al2O3 in raw materials) × 100. The results are shown in Table 1.
[0052] (2) Test of catalytic performance: The copper-based molecular sieves prepared in the above examples and comparative examples were pressed into tablets and sieved, and molecular sieves with a mesh size of 40-600 were used as catalysts for experiments or treatments.
[0053] The obtained molecular sieve was placed in a mixture of [NO] = [NH3] = 500 ppm, [O2] = [H2O] = 5 vol%, N2 as the balance gas, and a total flow rate of 500 ml / min. The air velocity was 400,000 h -1 The catalytic reaction test was carried out under the conditions of , and the results are shown in Table 1:
[0054] Table 1
[0055]
[0056] From the test results in Table 1 above, we can see that:
[0057] (1) It can be seen from Examples 1 to 4 that the present invention optimizes the synthesis method of Cu-KFI molecular sieve by regulating the mixing process, and adopting the crystallization process and the one-step post-treatment process. At the same time, it effectively improves the preparation yield of Cu-KFI molecular sieve, and improves the catalytic activity and hydrothermal stability of the obtained Cu-KFI molecular sieve.
[0058] Figure 1 A nitrogen oxide conversion rate curve diagram of the copper-based molecular sieve prepared in Example 1 as a catalyst is shown. It can be seen from the figure that the Cu-KFI molecular sieve prepared in Example 1 has excellent catalytic activity.
[0059] (2) It can be seen from Example 1 and Example 2 that in the present invention, if the content of the Cu source and the second template added is reduced, it may result in less active Cu species in the product and poor low-temperature catalytic activity.
[0060] (3) By comparing Example 1 with Examples 3 and 4, it can be seen that if the crystallization temperature or calcination time is adjusted, the yield of Cu-KFI may be affected and the nitrogen oxide conversion efficiency of the catalyst may be affected.
[0061] (4) By comparing Example 1 with Comparative Example 1, it can be seen that if the second template is not added in the present invention, the active Cu species cannot enter the molecular sieve pores during the crystallization process, and the obtained catalyst activity is poor.
[0062] (5) By comparing Example 1 and Comparative Example 2, it can be seen that if the calcination temperature is too low, the template agent cannot be calcined completely, affecting the catalyst activity.
[0063] (6) By comparing Example 1 and Comparative Example 3, it can be seen that if the crystallization temperature is too low, the catalyst yield will be too low, affecting the nitrogen oxide conversion efficiency.
[0064] In summary, the present invention obtains copper-based molecular sieves by crystallization under alkaline environment, omits the cumbersome process of multi-step ion exchange reaction, reduces the preparation process, saves production cost, and prepares copper-based molecular sieves with excellent catalytic activity and hydrothermal stability. Secondly, the present invention helps to disperse and dissolve each substance in the raw material by regulating the mixed process of silicon source, aluminum source, copper source and template agent in the raw material, improves the crystallization rate and the crystallinity of the product molecular sieve, and effectively improves the yield of preparing copper-based molecular sieves. Furthermore, the present invention uses an acid solution or an ammonium salt solution to treat the reaction system after crystallization by a one-step post-treatment, regulates the existence state of Cu species in the molecular sieve, on the one hand, improves the dispersibility of Cu species in the molecular sieve, and on the other hand, improves the activity of copper-based molecular sieves, thereby further improving the catalytic performance of the molecular sieve.
[0065] Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field and related fields without creative work should fall within the scope of protection of the present invention. The structures, devices and operating methods not specifically described and explained in the present invention are implemented according to the conventional means in the field unless otherwise specified and limited.
Claims
1. A method for preparing Cu-KFI molecular sieve, characterized in that: The steps include: S1: mixing a silicon source, an aluminum source, an alkali source, a first template and a first solvent for a first time to obtain a solution A; mixing a copper source, a second template and a second solvent for a second time to obtain a solution B; S2: Mixing solution A and solution B for the third time, and performing a post-treatment on the system after reaction crystallization to obtain a Cu-KFI molecular sieve; wherein the reagent for the post-treatment comprises an acid solution and / or an ammonium salt solution.
2. The method for preparing a Cu-KFI molecular sieve according to claim 1, characterized in that: The first template in S1 is a quaternary ammonium salt organic template; the second template includes one or more of tetraethylenepentamine, triethylenetetramine, diethylenetriamine or ammonia water.
3. The method for preparing a Cu-KFI molecular sieve according to claim 1, characterized in that: The silicon source in S1 includes one or more of silica sol, sodium silicate, fumed silica, silica gel, Y molecular sieve, Beta molecular sieve or ZSM-5 molecular sieve; the aluminum source includes one or more of sodium aluminate, aluminum hydroxide, aluminum sulfate, pseudo-boehmite, Y molecular sieve, Beta molecular sieve or ZSM-5 molecular sieve; the alkali source includes sodium hydroxide and / or potassium hydroxide; the copper source includes one or more of copper sulfate, copper acetate, copper nitrate or copper chloride.
4. The method for preparing a Cu-KFI molecular sieve according to claim 1, characterized in that: The molar ratio of the silicon source to the aluminum source in S1 is (1-50):1; the molar ratio of the silicon source to the alkali source is (1-30):1; the molar ratio of the silicon source to the first template is (1-30):1; the molar ratio of the copper source to the second template is (0.1-1.5):1; in the third mixing in S2, the molar ratio of the silicon source to the copper source is (1-1000):
1.
5. The method for preparing a Cu-KFI molecular sieve according to claim 1, characterized in that: The temperature ranges of the first mixing, the second mixing and the third mixing are 10-80°C respectively; the rotation speeds of the first mixing, the second mixing and the third mixing are 10-2000r / min; the time of the first mixing, the second mixing and the third mixing is 0.5-16h; The reaction crystallization temperature in S2 is 120-200°C; the reaction crystallization time is 1-336h; the reaction crystallization is carried out under non-stirring closed conditions; the product after crystallization is cooled and separated.
6. The method for preparing a Cu-KFI molecular sieve according to claim 1, characterized in that: The H+ concentration in the acid solution of the post-treatment step in S2 is 0.01-0.2 mol / L; the concentration of the ammonium salt solution is 0.01-0.5 mol / L; the treatment time is 1-24h; the acid solution includes one or more of hydrochloric acid, nitric acid or sulfuric acid; the ammonium salt solution includes one or more of ammonium chloride, ammonium nitrate or ammonium sulfate.
7. The method for preparing a Cu-KFI molecular sieve according to claim 1, characterized in that: The product after the one-step post-treatment needs to be washed, dried and calcined to obtain the copper-based molecular sieve; the drying temperature is 40-160°C; the calcination heating rate is 0.5-5°C / min; the calcination temperature is 500-900°C; and the calcination insulation time is 5-10h.
8. A Cu-KFI molecular sieve, characterized in that The method is prepared by any one of claims 1 to 7.
9. Use of the Cu-KFI molecular sieve according to claim 8 in nitrogen oxide conversion.