A method for preparing SSZ-39 molecular sieve and metal composite SSZ-39 catalyst

Abstract

This invention belongs to the field of molecular sieve preparation technology, specifically relating to an SSZ-39 molecular sieve, its preparation method, and its applications. A first aluminum source is added to a strong alkaline aqueous solution to form an aluminate solution. Subsequently, a first silicon source is added, and the mixture is kept at 80-120°C for 12-48 hours to form an amorphous / low long-programmed aluminosilicate precursor seed suspension without the addition of an organic structure-directing agent. Then, a second silicon source is added, mixed thoroughly, and an organic structure-directing agent is added and mixed thoroughly again. The mixture is then transferred to a high-pressure hydrothermal synthesis reactor and reacted at 160-200°C for 2-6 days. After purification and drying, the SSZ-39 molecular sieve is obtained. A second aluminum source can be added simultaneously with the second silicon source to control the aluminum-silicon ratio, or a transition metal soluble salt can be added to load the active ingredient. This invention achieves selective crystallization of AEI topology in a continuous process without separating the precursor seed. Compared to the traditional process of "removing the seed for reuse," it has the advantages of shortening the induction period, widening the crystallization window, and improving batch-to-batch consistency and production efficiency.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of catalyst preparation, and particularly relates to a preparation method of SSZ-39 molecular sieve and metal composite SSZ-39 catalyst. BACKGROUND

[0002] As a member of the zeolite molecular sieve family, SSZ-39 molecular sieve has the characteristics of microporous structure and large specific surface area, and is suitable for adsorption and catalytic reaction. It can play a role in the fields of hydrocarbon conversion, gasoline cracking, catalytic cracking and selective catalytic reduction of nitrogen oxides by adjusting the pore size and chemical composition. At present, SSZ-39 molecular sieve has shown important application prospects in automobile exhaust treatment, industrial waste gas treatment and clean energy production, and provides a new solution for environmental protection and clean energy development.

[0003] For the synthesis of SSZ-39 molecular sieve supported metal catalyst, researchers currently use seed-assisted method and hydrothermal method to synthesize SSZ-39 molecular sieve, and need to add an organic structure directing agent, and then obtain the SSZ-39 molecular sieve supported metal catalyst through ion exchange method or impregnation method. The catalyst preparation steps are complicated and the preparation period is long. Hu et al. synthesized SSZ-39 molecular sieve seeds by using conventional hydrothermal method, and the raw materials were deionized water, silica sol LUDOX® AS-40, NaOH, TMPOH and USY zeolite. After calcination, the NH4 type zeolite was obtained by two times of ion exchange in 1 M NH4NO3 solution. The NH4 type zeolite was ion exchanged with 3% Cu(CH3COO)2·H2O solution at 90°C for 1 h to obtain Cu-SSZ-39.

[0004] Xu et al. used deionized water, Y-type zeolite (SiO2 / Al2O3=21.6), DPOH and NaOH as raw materials, and finally obtained the product SSZ-39-c through crystallization, filtration, washing, drying and calcination. The product was ion exchanged with 1 mol·L -1 NH4NO3 solution, and H-SSZ-39-c sample was obtained by calcination at 550°C for 4 h.

[0005] Mao et al. used 2,6-dimethylpiperidine as the starting material, and obtained N,N-diethyl-2,6-dimethylpiperidine base (DEDMP + OH -) structure directing agent. The SSZ-39 molecular sieve is prepared from N,N-diethyl-2,6-dimethylpiperidine base solution, NaOH, H2O, silica sol and HY molecular sieve as raw materials through crystallization, washing, drying and calcination. The catalysts M-SSZ-39, H-SSZ-39, Ce-SSZ-39, Sr-SSZ-39 and K-SSZ-39 molecular sieves are obtained by ion exchange with MNO3 aqueous solution (M = NH4, K, Ce, Sr) under hydrothermal conditions, and then through filtration, washing, drying and calcination.

[0006] These studies are of great significance for the development of efficient and low-cost metal-loaded SSZ-39 catalysts, and provide a feasible technical approach to improve environmental governance and energy utilization efficiency.

[0007] There are many technical problems in the synthesis of the SSZ-39 molecular sieve catalyst. First, the SSZ-39 molecular sieve synthesized by the hydrothermal method needs to use expensive structure directing agents, and the synthesis conditions are very strict. Moreover, after the synthesis of the SSZ-39 molecular sieve, a complicated metal loading step is needed, which increases the complexity and cost of synthesis. Second, the seed-assisted method for synthesizing the SSZ-39 molecular sieve challenges the rule that the initial zeolite material has a low framework density to a high zeolite framework density, and has a high requirement for the organic structure directing agent. It is difficult to realize the conversion between molecular sieves, and the yield is also low. In addition, the synthesis of the SSZ-39 currently needs to use expensive molecular sieve raw materials such as Y, ZSM-5 or Beta molecular sieve, which further increases the synthesis cost. SUMMARY

[0008] The present application provides a preparation method of SSZ-39 molecular sieve and metal composite SSZ-39 catalyst to reduce the cost of the catalyst with SSZ-39 molecular sieve as the carrier.

[0009] In order to achieve the above-mentioned application purposes, the present application provides the following technical solutions.

[0010] In a first aspect, the present application provides a preparation method of SSZ-39 molecular sieve, comprising the following steps:

[0011] adding a first aluminum source into a strong alkali aqueous solution to obtain a partial aluminate solution;

[0012] adding a first silicon source into the partial aluminate solution and mixing uniformly to obtain solution A; and keeping the solution A at 80-120 DEG C for 12-48 hours to obtain a precursor seed suspension;

[0013] adding a second silicon source to the precursor seed suspension and mixing uniformly, and then adding an organic structure directing agent (OSDA) and mixing uniformly to obtain solution B; transferring the solution B to a high-pressure hydrothermal synthesis kettle, and reacting at 160-200℃ for 2-6 days to obtain SSZ-39 molecular sieve crystals with an AEI topology structure, and sequentially performing purification and drying to obtain the SSZ-39 molecular sieve.

[0014] In some embodiments of the present application, the pH of the solution A is > 12, and the concentration of the first silicon source in the solution A is ≥ 10 wt% in terms of SiO2.

[0015] In some embodiments of the present application, the molar ratio of the first silicon source in terms of SiO2 to the first aluminum source in terms of Al2O3 is 1:0.01-0.30.

[0016] In some embodiments of the present application, the molar ratio of the second silicon source in terms of SiO2 to the organic structure directing agent is 1:0.3-0.80.

[0017] In some embodiments of the present application, the organic structure directing agent is 1,1,3,5-tetramethylpiperidinium hydroxide (TMPAOH).

[0018] In some embodiments of the present application, the mass ratio of the second silicon source to the first silicon source is 1.0-2.0:1 in terms of SiO2.

[0019] In some embodiments of the present application, a second aluminum source is added to the precursor seed suspension at the same time as the second silicon source, and the molar ratio of the second silicon source in terms of SiO2 to the second aluminum source in terms of Al2O3 is 1:0.01-0.2.

[0020] In some embodiments of the present application, a transition metal soluble salt is added to the precursor seed suspension at the same time as the second silicon source.

[0021] In a second aspect, the present application provides a SSZ-39 molecular sieve prepared by the above method for preparing a SSZ-39 molecular sieve.

[0022] In a third aspect, the present application provides use of the above SSZ-39 molecular sieve in the field of NH3-SCR catalysis.

[0023] Compared with the prior art, the present application has at least the following beneficial effects:

[0024] The application adds a silicon source to a high-concentration meta-aluminate solution, incubates at 80-120 DEG C to form a precursor seed suspension, then supplements a silicon source and / or an aluminum source to make the precursor seed grow directionally into SSZ-39 molecular sieve crystals, compared with the traditional method, the application shortens the synthesis period of the precursor seed, compared with the traditional method of taking out the precursor seed for treatment and then using, the application greatly improves the production efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative effort.

[0026] Figure 1 SEM image of SSZ-39-R1 prepared in Example 1.

[0027] Figure 2 XRD image of SSZ-39-R1 prepared in Example 1.

[0028] Figure 3 SEM image of Cu / SSZ-39-R2 prepared in Example 2.

[0029] Figure 4 XRD image of Cu / SSZ-39-R2 prepared in Example 2.

[0030] Figure 5 SEM image of Fe / SSZ-39-R3 prepared in Example 3.

[0031] Figure 6 XRD image of Fe / SSZ-39-R3 prepared in Example 3.

[0032] Figure 7 SEM image of Pd / SSZ-39-R4 prepared in Example 4.

[0033] Figure 8 XRD image of Pd / SSZ-39-R4 prepared in Example 4.

[0034] Figure 9 SEM image of Cu / SSZ-39-R5 prepared in Example 5.

[0035] Figure 10 XRD image of Cu / SSZ-39-R5 prepared in Example 5.

[0036] Figure 11 SEM image of Co / SSZ-39-R6 prepared in Example 6.

[0037] Figure 12 XRD pattern of Co / SSZ-39-R6 prepared in Example 6.

[0038] Figure 13 SEM image of SSZ-39-R7 prepared in Example 7.

[0039] Figure 14 SEM image of SSZ-39-R7 prepared in Example 7.

[0040] Figure 15 Example 2: The NO content of Cu / SSZ-39-R2 prepared in Example 2 and a commercially available Cu / SSZ-39 catalyst at high temperature. x Conversion rate comparison chart.

[0041] Figure 16 Comparison of the hydrothermal stability of Cu / SSZ-39-R2 prepared in Example 2 and commercially available Cu / SSZ-39 catalyst.

[0042] Figure 17 XRD pattern of the precursor seed obtained in Example 1. Detailed Implementation

[0043] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with the embodiments of this invention. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0044] For simplicity, this paper only explicitly discloses some numerical ranges. However, any lower limit can be combined with any upper limit to form an undefined range; and any lower limit can be combined with other lower limits to form an undefined range. Similarly, any upper limit can be combined with any other upper limit to form an undefined range. Furthermore, although not explicitly stated, every point or individual value between the endpoints of a range is included within that range. Therefore, each point or individual value can be used as its own lower or upper limit, combined with any other point or individual value, or combined with other lower or upper limits to form an undefined range.

[0045] It should be noted that in the description of the present document, unless otherwise specified, "above", "below" include the number, "a plurality of" in "one or more" means two or more. The relationship terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between the entities or operations. Moreover, the terms "include", "contain" or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or device including a series of elements not only includes those elements, but also includes other elements not explicitly listed or inherent to such process, method, article or device. Without more limitations, the element defined by the statement "including a" does not exclude the presence of other identical elements in the process, method, article or device including the element.

[0046] In the description of the present specification, the description of the terms "any embodiment / way", "one embodiment / way", "some embodiments / ways", "example", "specific example" or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment / way or example are included in at least one embodiment / way or example of the present application. In the present specification, the illustrative description of the above terms does not necessarily refer to the same embodiment / way or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any appropriate manner in any one or more embodiments / ways or examples. In addition, the skilled person in the art can combine and combine different embodiments / ways or examples described in the present specification and the features of different embodiments / ways or examples without contradiction.

[0047] The above summary of the present application is not intended to describe each disclosed embodiment or each implementation of the present application. The following description illustrates the exemplary embodiments in more detail. These embodiments can be used in various combinations. In each instance, the enumeration is only representative of a group and should not be interpreted as exhaustive.

[0048] The term "silicon aluminum ratio" in the present application, abbreviated as SAR, refers to the atomic number ratio of silicon atoms and aluminum atoms in the molecular sieve, which is determined by the proportion relationship of silicon oxygen tetrahedron and aluminum oxygen octahedron in the mineral structure. The higher the silicon aluminum ratio of the mineral, the smaller the isoelectric point pH value.

[0049] The preparation method of the SSZ-39 molecular sieve provided by the present application comprises the following steps:

[0050] The first aluminum source is added to the strong alkali aqueous solution to obtain a partial aluminate solution;

[0051] Add a first silicon source to the aluminate solution and mix thoroughly to obtain solution A; keep solution A at 80~120℃ for 12~48 hours to obtain a precursor seed suspension;

[0052] Add a second silicon source to the precursor seed suspension and mix well, then add an organic structure directing agent and mix well to obtain solution B;

[0053] The solution B was transferred to a high-pressure hydrothermal synthesis reactor and reacted at 160-200℃ for 2-6 days to obtain SSZ-39 molecular sieve crystals with AEI topology. The crystals were then purified and dried to obtain SSZ-39 molecular sieve.

[0054] This invention employs a synergistic mechanism of "template-free aging – two-step silicon replenishment – ​​template-oriented crystallization" to prepare AEI topological SSZ-39 molecular sieves. The principle is as follows:

[0055] First, the first aluminum source is added to an excess of a strong alkaline aqueous solution to form an aluminate solution, in which AlO2 is present. - It combines with water to form tetrahydroxyaluminate ions [Al(OH)4]. - (Reaction: AlO2) - + 2H₂O → [Al(OH)₄] - When the first silicon source is added in a strongly alkaline environment with pH > 12, the silicon source dissociates into silicon-oxygen species (such as Si(OH)4, [SiO(OH)3)) in the strongly alkaline solution. - ), silicon-oxygen species and [Al(OH)4] - Aluminosilicate oligomer network with Al-O-Si bond backbone is formed through hydroxyl dehydration condensation reaction. This network is further crosslinked and granulated under aging conditions of 80–120 °C for 12–48 h to obtain a precursor seed suspension without organic structure-directing agents: such as... Figure 17 As shown, the XRD pattern of the precursor seed only shows a diffuse background and does not show FAU / AEI crystal-resolved diffraction peaks, indicating that the precursor seed is a non-molecular sieve crystal product, but an amorphous or low-length-order phase. The silicon-oxygen species were not completely crystallized by keeping the solution A at 80~120℃ for 12~48 hours.

[0056] The application takes the precursor seed as a nucleation / structure induction center for subsequent crystallization to shorten the induction period and improve the AEI crystal growth selectivity: a second silicon source is added to the precursor seed suspension and uniformly dispersed, and then an organic structure directing agent 1,1,3,5-tetramethylpiperidinium ammonium hydroxide is introduced. Under the electrostatic / spatial steric matching effect of the OSDA, the silicon-aluminum framework is directionally rearranged and continuously polymerized on the seed interface, and under hydrothermal conditions (160-200 ℃, 2-6 days), the SSZ-39 crystal with AEI topology is preferentially grown. The two-step silicon supplementation design maintains a high flux of active silicon oxide species on the one hand, ensuring continuous nucleation-growth, and on the other hand, can cooperate with the second aluminum source added synchronously to refine the Si / Al distribution of the framework and modify defects, thereby improving the robustness of the crystallization window and the batch-to-batch repeatability of the sample. Without inhibiting AEI crystallization, the transition metal soluble salt (such as nitrate / chloride / acetic salt of Cu, Fe, Pd, etc.) added in step (3) can realize precursor complexation-site anchoring and dispersion control during the formation of the framework / pore, providing active centers or precursor sites for subsequent applications. In summary, through the process synergy of "OSDA-free amorphous precursor seed + two-step silicon supplementation + OSDA direction", the application realizes effective induction of AEI topology selective crystallization, and gives the material controllable framework composition and potential active site introduction capability.

[0057] In some embodiments of the application, the pH of the solution A is ≥10, and the concentration of the first silicon source in the solution A is ≥10 wt% in terms of SiO2. The pH of the solution A is >12 because the strong alkali aqueous solution is in excess relative to the total amount of the first aluminum source and the first silicon source, and the strong alkali aqueous solution can ensure that the first aluminum source can still exist in the form of [Al(OH)4] - after the first silicon source is added, while ensuring that the first silicon source is dissociated into silicon oxide species. The formation of the precursor seed suspension depends on the nucleation and growth of the aluminosilicate precursor particles, and the concentration of the first silicon source in the solution A is ≥10 wt%. The concentration of the first silicon source in the solution is high, and the probability of collision with the first aluminum source is high, so the nucleation efficiency is high, and because the first silicon source is sufficient to grow, a stable precursor seed suspension is formed. When the concentration of the first silicon source is too low, the nucleation efficiency is reduced, and the nucleus is difficult to grow due to the lack of the first silicon source, and thus it is difficult to form a stable precursor seed suspension.

[0058] In some embodiments of the application, the concentration of the first aluminum source in the met aluminate solution is 5wt%-10wt% in terms of Al2O3, and is preferably 7wt%. This concentration can ensure the formation of a stable precursor seed suspension.

[0059] In some embodiments of the present application, the concentration of the strong alkali aqueous solution is ≥ 8 wt%; preferably, the concentration of the strong alkali aqueous solution is ≥ 10 wt%; more preferably, the concentration of the strong alkali aqueous solution is ≥ 15 wt%. Preferably, the concentration of the strong alkali aqueous solution is 15 wt% to 20 wt%. In an embodiment of the present application, the concentration of the strong alkali aqueous solution is 16 wt%, and the strong alkali is sodium hydroxide. This concentration can quickly dissolve the first aluminum source.

[0060] In some embodiments of the present application, the molar ratio of the first silicon source calculated based on SiO2 to the first aluminum source calculated based on Al2O3 is 1:0.01 to 0.30. The aluminum species [Al(OH)4] - In the silicon-aluminum-oxygen oligomer, the silicon-oxygen species is connected to the aluminum species through Al-O-Si bonds, which are the crosslinking centers of the three-dimensional structure of the oligomer. If the number of aluminum species is too small, the density of Al-O-Si bonds is insufficient, and the silicon-oxygen species is prone to self-polymerization into pure silicon-oxygen oligomers without aluminum crosslinking through Si-O-Si bonds. Such oligomers have loose structures and lack the rigid support of aluminum sites, and thus cannot form stable precursor seed structures, which are prone to be converted into amorphous silica gels. If the proportion of aluminum species is too high, unstable Al-O-Al bonds are easily formed: the bond energy of Al-O-Al bonds is lower than that of Al-O-Si bonds, and Al-O-Al bonds are prone to hydrolysis and rupture in an alkaline solution, leading to the collapse of the oligomer structure and the inability to form a short-range ordered precursor seed structure.

[0061] In some embodiments of the present application, the molar ratio of the second silicon source calculated based on SiO2 to the organic structure-directing agent is 1:0.3 to 0.8. The mass ratio of the second silicon source to the first silicon source calculated based on SiO2 is 1.0 to 2.0:1. The second silicon source is used to supplement the silicon demand in the crystal growth stage. The silicon-aluminum ratio in the precursor seed is low, and the addition of the second silicon source can adjust the silicon-aluminum ratio of the SSZ-39 molecular sieve crystals to the designed ratio. In some embodiments of the present application, the designed silicon-aluminum ratio is 8 to 15.

[0062] In some embodiments of the present application, the second silicon source and the second aluminum source are added to the precursor seed suspension at the same time. The molar ratio of the second silicon source calculated based on SiO2 to the second aluminum source calculated based on Al2O3 is 1:0.01 to 0.2. The purpose of adding the second aluminum source is to regulate the silicon-aluminum ratio of the final SSZ-39. If the first aluminum source has met the total aluminum demand, the second aluminum source can not be added.

[0063] In some embodiments of the present application, the organic structure-directing agent is 1,1,3,5-tetramethylpiperidinium ammonium hydroxide. The 1,1,3,5-tetramethylpiperidinium ammonium hydroxide can induce the assembly of silicon-aluminum species around it into an AEI topology structure, ensuring that the product is pure SSZ-39 molecular sieve.

[0064] In some embodiments of the present application, the first aluminum source is one or more of aluminum isopropoxide, aluminum hydroxide, sodium metaaluminate, alumina, and pseudoboehmite; and / or, the strong base is at least one of NaOH, KOH, and LiOH.

[0065] In some embodiments of the present application, a soluble salt of the catalytically active component is added to the precursor seed suspension at the same time as the second silicon source is added. The present application can introduce the catalytically active component during the crystal growth stage, which can be incorporated into the molecular sieve channels or framework by ion exchange or in-situ doping, thereby improving the dispersibility of the catalytically active component.

[0066] In some embodiments of the present application, the catalytically active component is a transition metal, the transition metal M is selected from one or more of Cu, Fe, Pd, Co, Mn, Ni, Pt, and Ru, and the anion of the soluble salt is selected from one or more of nitrate, chloride, and acetate; the molar ratio of M to SiO2 in solution B is 1:10000-20, calculated based on the transition metal M. Preferably, M is one or more of Cu, Fe, and Pd.

[0067] In some embodiments of the present application, the purification comprises: centrifuging the sample in the high-pressure hydrothermal synthesis kettle, and washing the centrifuged product to neutral.

[0068] The present application also provides an SSZ-39 molecular sieve prepared by the above method for preparing SSZ-39 molecular sieve. As shown in Examples 8 and 9, the NH3-SCR catalytic activity and hydrothermal stability of the Cu / SSZ-39 molecular sieve catalyst obtained in Example 2 of the present application are significantly higher than those of a commercially available Cu / SSZ-39 catalyst.

[0069] The technical solutions of the present application are described in detail below through specific examples. The commercially available Cu / SSZ-39 catalyst used in the following examples or comparative examples was purchased from Tianjin Paixun New Material Technology Co., Ltd.

[0070] Example 1: Synthesis of a target product with a silicon-aluminum ratio of 9

[0071] S1. At room temperature, 0.75 g of sodium metaaluminate was dissolved in 6 mL of a 16 wt% NaOH aqueous solution, and stirred until the sodium metaaluminate was completely dissolved to obtain a metaaluminate solution;

[0072] S2. 8.6 g of silica sol (20 wt%) was added to the metaaluminate solution, and stirred again to obtain solution A; solution A was transferred into a stainless steel hydrothermal synthesis kettle with a polytetrafluoroethylene lining, and placed in a constant temperature oven for pre-crystallization at 100°C for 24 hours to obtain a precursor seed suspension (pH = 10); the precursor seed suspension was centrifuged, and the centrifuged product was washed to neutral and dried at 90°C to obtain a precursor seed, which was detected by an X-ray diffractometer (XRD), and the results are shown inFigure 17 ;

[0073] S3. Add 14 g of silica sol (20 wt% of SiO2) to the precursor seed suspension, stir at 100 ℃ for 30 min, add 4.8 g of TMPOH, continue to stir at 100 ℃ for 2 h to obtain solution B; transfer solution B to a high-pressure hydrothermal synthesis kettle, react at 180 ℃ for 4 days, after the reaction is completed, centrifuge the sample in the reaction kettle, wash the centrifuged product to neutral, and dry at 90 ℃ to obtain the target product, named SSZ-39-R1.

[0074] SSZ-39-R1 was detected by scanning electron microscopy (SEM) and X-ray diffractometry, respectively. As can be seen from the SEM image shown in FIG. 1, SSZ-39-R1 is a cubic crystal with a size of 500 nm. Figure 1 As can be seen from the XRD pattern shown in FIG. 2, the cubic crystal is SSZ-39 molecular sieve with AEI framework structure. Figure 2

[0075] Example 2: Synthesis of target product with a silicon-aluminum ratio of 9 and doped with Cu

[0076] S1. Dissolve 0.75 g of sodium metaaluminate in 6 mL of 16 wt% NaOH aqueous solution at room temperature, stir until the sodium metaaluminate is completely dissolved to obtain a metaaluminate solution;

[0077] S2. Add 8.6 g of silica sol (20 wt%) to the metaaluminate solution, and stir again to obtain solution A; transfer solution A into a stainless steel hydrothermal synthesis kettle with a polytetrafluoroethylene liner, and place it in a constant temperature oven for pre-crystallization at 80 ℃ for 16 h to obtain a precursor seed suspension (pH = 10);

[0078] S3. Add 9 g of silica sol (20 wt% of SiO2) to the precursor seed suspension, stir at 80 ℃ for 30 min, add 0.1987 g of Cu(NO3)2·3H2O and 4.8 g of TMPOH, continue to stir at 80 ℃ for 2 h to obtain solution B; transfer solution B to a high-pressure hydrothermal synthesis kettle, react at 170 ℃ for 5 days, after the reaction is completed, centrifuge the sample in the reaction kettle, wash the centrifuged product to neutral, and dry at 90 ℃ to obtain the target product, named Cu / SSZ-39-R2.

[0079] Cu / SSZ-39-R2 was detected by scanning electron microscopy and X-ray diffractometry, respectively. As can be seen from the SEM image shown in FIG. 4, Cu / SSZ-39-R2 prepared by one-pot method is a crystal with a rough surface and a particle size of 1-2 μm. As can be seen from the XRD pattern shown in FIG. 5, the crystal is SSZ-39 molecular sieve with AEI framework structure. Figure 3 Figure 4 ​​The XRD pattern shown can see that the prepared sample is SSZ-39 molecular sieve with AEI framework structure.

[0080] Example 3: Synthesis of target product doped with Fe with a silicon-aluminum ratio of 9

[0081] S1. At room temperature, 0.938 g of sodium metaaluminate was dissolved in 6 mL of an aqueous NaOH solution with a concentration of 16 wt%, and stirred until the sodium metaaluminate was completely dissolved to obtain a metaaluminate solution;

[0082] S2. 8.6 g of silica sol (20 wt%) was added to the metaaluminate solution, and stirred again to obtain solution A; solution A was transferred into a stainless steel hydrothermal synthesis kettle with a polytetrafluoroethylene liner, and placed in a constant temperature oven for pre-crystallization at a temperature of 100°C for 24 hours to obtain a precursor seed suspension (pH = 10);

[0083] S3. 14 g of silica sol (20 wt% of silica) was added to the precursor seed suspension, and stirred at 100°C for 30 minutes, 0.3819 g of Fe(NO3)3·9H2O and 4.8 g of TMPOH were added, and stirring was continued at 100°C for 2 hours to obtain solution B; solution B was transferred into a high-pressure hydrothermal synthesis kettle, and reacted at 160°C for 6 days; after the reaction was completed, the sample in the reaction kettle was centrifuged, and the centrifuged product was washed to neutral, and dried at 90°C to obtain the target product, which was named Fe / SSZ-39-R3.

[0084] Fe / SSZ-39-R3 was ground into a powder, and was detected on a scanning electron microscope and an X-ray diffractometer, respectively. From the SEM pattern shown, Figure 5 The SEM pattern shown can see that the prepared Fe / SSZ-39-R3 is a sheet-shaped crystal with a size of 100 nm. From the XRD pattern shown, Figure 6 The XRD pattern shown can see that the prepared Fe / SSZ-39-R3 is SSZ-39 molecular sieve with AEI structure.

[0085] Example 4: Synthesis of target product doped with Pd with a silicon-aluminum ratio of 9

[0086] S1. At room temperature, 0.938 g of sodium metaaluminate was dissolved in 6 mL of an aqueous NaOH solution with a concentration of 16 wt%, and stirred until the sodium metaaluminate was completely dissolved to obtain a metaaluminate solution;

[0087] S2. 4.3 g of silica sol (40 wt%) was added to the metaaluminate solution, and stirred again to obtain solution A; solution A was transferred into a stainless steel hydrothermal synthesis kettle with a polytetrafluoroethylene liner, and placed in a constant temperature oven for pre-crystallization at a temperature of 100°C for 24 hours to obtain a precursor seed suspension (pH = 10);

[0088] S3. 4.55 g of silica sol (40 wt% of SiO2) was added into the precursor seed suspension, stirred at 100 ℃ for 30 min, 0.0661 g of Pd(NO3)2·2H2O and 0.01483 g of ethylenediamine (EDA, n(Pd(NO3)2·2H2O):n(ethylenediamine) = 1:1) were added, stirred for 30 min, 4.8 g of TMPOH was added, and the solution was aged again for 2 h to obtain solution B; solution B was transferred into a high-pressure hydrothermal synthesis kettle, and reacted at 180 ℃ for 4 days. After the reaction was completed, the sample in the reaction kettle was centrifuged, and the centrifuged product was washed to neutral and dried at 90 ℃ to obtain the target product, which was named as Pd / SSZ-39-R4.

[0089] The Pd / SSZ-39-R4 was ground into powder and detected on a scanning electron microscope and an X-ray diffractometer, respectively. Figure 7 As can be seen from the SEM image shown in FIG. 4, the prepared Pd / SSZ-39-R4 was a cubic crystal with a particle size of about 1 μm. Figure 8 As can be seen from the XRD image shown in FIG. 5, the prepared Pd / SSZ-39-R4 was a pure phase of SSZ-39 with AEI structure.

[0090] Example 5: Synthesis of a target product with a Si / Al ratio of 9 and doped with Cu

[0091] S1. At room temperature, 0.938 g of sodium metaaluminate was dissolved in 6 mL of an aqueous NaOH solution with a concentration of 16 wt%, and stirred until the sodium metaaluminate was completely dissolved to obtain a metaaluminate solution;

[0092] S2. 4.3 g of silica sol (40 wt%) was added into the metaaluminate solution, and stirred again to obtain solution A; solution A was transferred into a stainless steel hydrothermal synthesis kettle with a polytetrafluoroethylene liner, and placed in a constant temperature oven for pre-crystallization at 100 ℃ for 24 h to obtain a precursor seed suspension (pH = 10);

[0093] S3. 4.55 g of silica sol (40 wt% of SiO2) was added into the precursor seed suspension, stirred at 100 ℃ for 30 min, 4.8 g of TMPOH was added, and the solution was aged again for 2 h to obtain solution B; solution B was transferred into a high-pressure hydrothermal synthesis kettle, and reacted at 180 ℃ for 4 days.

[0094] The gel composition was 10 SiO2:0.7758 Al2O3:3.814 NaOH:1.277 template 1,1,3,5-tetramethylpiperidinium hydroxide (TMPOH):114.35 H2O. The product was collected by vacuum filtration, washed thoroughly, and dried at 80 ℃. The molar ratio of Si / Al was about 8-9.

[0095] H-SSZ-39 was obtained by calcination at 600 °C for 6 hours, followed by ion exchange in 1 M NH4Cl solution, ion exchange at 80 °C for 8 hours, centrifugation and oven drying of the product, and calcination at 550 °C for 8 h. Subsequently, a solution containing 4% Cu (0.1588 g CuSO4·5H2O and 0.8 mL H2O) was added dropwise to a grinding of the H-type zeolite (1 g). The resulting product was calcined at 550 °C for 5 h to obtain the fresh target product, designated Cu / SSZ-39-R5.

[0096] Cu / SSZ-39-R5 was detected by scanning electron microscope and X-ray diffractometer, respectively. The SEM image shown in Fig. 1 shows that the prepared Cu / SSZ-39-R5 is a cubic crystal with a size of about 0.5-1 μm. Figure 9 The SEM image shown in Fig. 1 shows that the prepared Cu / SSZ-39-R5 is a cubic crystal with a size of about 0.5-1 μm. Figure 10 The XRD pattern shown in Fig. 2 shows that the prepared Cu / SSZ-39-R5 has complete AEI crystal structure characteristic peaks, indicating that the synthesized sample is a Cu-doped SSZ-39 zeolite molecular sieve sample.

[0097] Example 6: Synthesis of a target product with a silicon-aluminum ratio of 9 and doped with Co

[0098] S1. At room temperature, 0.72 g of sodium metaaluminate was dissolved in 6 mL of an aqueous NaOH solution with a concentration of 16 wt%, and stirred until the sodium metaaluminate was completely dissolved to obtain a metaaluminate solution;

[0099] S2. 4.3 g of silica sol (40 wt% of silica) was added to the metaaluminate solution, and stirred again to obtain solution A; solution A was transferred into a stainless steel hydrothermal synthesis tank with a polytetrafluoroethylene liner, and placed in a constant temperature oven for pre-crystallization at a temperature of 100 °C for 24 hours to obtain a precursor seed suspension (pH = 10);

[0100] S3. 4.55 g of silica sol (40 wt% concentration of SiO2) was added to the precursor seed suspension, stirred at 100 °C for 30 minutes, 4.8 g of TMPOH was added, and stirring was continued at 100 °C for 2 hours to obtain solution B; solution B was transferred to a high-pressure hydrothermal synthesis kettle, and reacted at 180 °C for 4 days. The initial gel composition was 10 SiO2: 0.7758 Al2O3: 3.814 NaOH: 1.277 TMPOH: 114.35 H2O. The product was collected by vacuum filtration, thoroughly washed, and dried at 80 °C to produce SSZ-39. The molar ratio of Si / Al was about 8-9. After calcination at 600 °C for 6 hours, ion exchange was carried out in 1 M NH4Cl solution at 80 °C for 8 hours, the product was centrifuged and dried, and H-SSZ-39 was obtained after calcination at 550 °C for 8 h. Subsequently, 4% Co source (0.2005 g of Co(NO3)2·6H2O and 0.8 mL of H2O) was added dropwise to the H-type zeolite (1 g) and ground. The resulting product was calcined at 550 °C for 5 h to obtain fresh Co / SSZ-39 zeolite, which was named Co / SSZ-39-R6.

[0101] Co / SSZ-39-R6 was detected by scanning electron microscopy and X-ray diffractometry, respectively, from which Figure 11 As can be seen from the SEM image shown in FIG. 1, the prepared Co / SSZ-39-R6 is a cubic crystal of about 0.5-1 um, from which Figure 12 As can be seen from the XRD pattern shown in FIG. 2, the prepared Co / SSZ-39-R6 has complete AEI crystal structure characteristic peaks, indicating that the synthesized sample is a Cu-doped SSZ-39 zeolite molecular sieve sample.

[0102] Example 7: Synthesis of a target product with a silicon-aluminum ratio of 15

[0103] S1. At room temperature, 0.72 g of pseudo-boehmite was dissolved in 6 mL of 16 wt% NaOH aqueous solution, and stirred until the sodium aluminates were completely dissolved to obtain a sodium aluminate solution;

[0104] S2. 8.6 g of silica sol (20 wt%) was added to the sodium aluminate solution, and stirred again to obtain solution A; solution A was transferred to a stainless steel hydrothermal synthesis kettle with a polytetrafluoroethylene liner, and placed in a constant temperature oven for pre-crystallization at 100 °C for 24 hours to obtain a precursor seed suspension (pH = 10);

[0105] S3. Add 22g of silica sol (silica concentration of 20wt%) to the precursor seed suspension, stir at 100℃ for 30 minutes, add 4.8g of TMPOH, and continue stirring at 100℃ for 2 hours to obtain solution B; transfer solution B to a high-pressure hydrothermal synthesis reactor, react at 180℃ for 4 days, after the reaction is completed, centrifuge the sample in the reactor, wash the centrifuged product until neutral, and dry at 90℃ to obtain the target product, named SSZ-39-R7.

[0106] SSZ-39-R7 was examined using a scanning electron microscope and an X-ray diffractometer, respectively. Figure 13 The SEM image shown indicates that the prepared crystal is a 500nm cubic crystal. From... Figure 14 The XRD pattern shown indicates that the crystal is an SSZ-39 molecular sieve with an AEI framework structure.

[0107] Example 8: NH3-SCR Catalytic Activity Test

[0108] The Cu / SSZ-39-R2 prepared in Example 2 and a commercially available Cu / SSZ-39 catalyst were tested for their NH3-SCR catalytic activity in a fixed-bed quartz reactor with an inner diameter of 6 mm. 0.1 g of catalyst with a particle size of 40–60 mesh was placed in the tubular reactor.

[0109] The test conditions were: 500 ppm NH3, 5 vol.% O2, and a balance gas N2. The total flow rate was 500 mL / min, and the weight hourly space velocity (WHSV) was approximately 60,000 mL·g. -1 ·h -1 The composition of the inlet and outlet gases was monitored using an FTIR spectrometer (MKS, MultiGas 2030HS). The NOx conversion rate was calculated using the following formula:

[0110]

[0111] like Figure 15 As shown, the Cu / SSZ-39-R2 prepared in Example 2 exhibits higher NO content at high temperatures compared to the commercially available Cu / SSZ-39 catalyst. x The better conversion rate indicates that the Cu / SSZ-39-R2 prepared in Example 2 of this invention exhibits superior DeNOx content. x Activity (100% conversion rate).

[0112] Example 9: Hydrothermal Aging Treatment of Catalyst

[0113] Cu / SSZ-39-R2 prepared in Example 2 of the present application and a commercial Cu / SSZ-39 catalyst were hydrothermally aged in flowing air containing 10% H2O by volume at 750 ℃ for 16 hours, named as sample-HTA. Then the NH3-SCR activity was tested to investigate the hydrothermal stability of the catalysts, and the results are shown in Figure 16 As shown in the figure, after hydrothermal treatment, the hydrothermal stability of Cu / SSZ-39-R2 prepared in Example 2 of the present application is significantly better than that of the commercial Cu / SSZ-39 catalyst, and still maintains a high activity (99%) after hydrothermal aging, showing excellent hydrothermal resistance.

[0114] The above description is merely that of a specific implementation of the present application, which enables a person skilled in the art to understand or implement the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to these embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method of making a SSZ-39 molecular sieve, characterized by, The method comprises the following steps: adding a first aluminum source into a strong alkali aqueous solution to obtain a meta-aluminate solution; adding a first silicon source into the meta-aluminate solution and mixing uniformly to obtain solution A, wherein the pH of the solution A is greater than or equal to 10, the concentration of the first silicon source in the solution A is greater than or equal to 10 wt% in terms of SiO2, and the molar ratio of the first silicon source in terms of SiO2 to the first aluminum source in terms of Al2O3 is 1:0.01-0.30; and the solution A is incubated at 80-120 ℃ for 12-48 hours to obtain a precursor seed suspension; adding a second silicon source into the precursor seed suspension and mixing uniformly, and then adding an organic structure directing agent 1,1,3,5-tetramethylpiperidinium ammonium hydroxide and mixing uniformly to obtain solution B; and transferring the solution B into a high-pressure hydrothermal synthesis kettle, reacting at 160-200 ℃ for 2-6 days to obtain SSZ-39 molecular sieve crystals with AEI topology, and sequentially performing purification and drying to obtain the SSZ-39 molecular sieve.

2. The method of making the SSZ-39 molecular sieve of claim 1, wherein: The molar ratio of the second silicon source in terms of SiO2 to the organic structure directing agent is 1:0.6-1.

60.

3. The method of making the SSZ-39 molecular sieve of claim 1, wherein: The mass ratio of the second silicon source to the first silicon source in terms of SiO2 is 1.0-2.0:

1.

4. The method of making the SSZ-39 molecular sieve of claim 1, wherein: The second aluminum source is added into the precursor seed suspension at the same time as the second silicon source, and the molar ratio of the second silicon source in terms of SiO2 to the second aluminum source in terms of Al2O3 is 1:0.01-0.

2.

5. The method of making the SSZ-39 molecular sieve of claim 1, wherein: The soluble salt of the catalytically active component is added into the precursor seed suspension at the same time as the second silicon source.

6. A SSZ-39 molecular sieve characterized by: The SSZ-39 molecular sieve is prepared by the method according to any one of claims 1-5.

7. The use of the SSZ-39 molecular sieve according to claim 6 in the field of NH3-SCR catalysis.

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