Cu-based SAPO-17 monolithic catalyst, its preparation method and application

Abstract

The application discloses a Cu-based SAPO-17 monolithic catalyst and a preparation method and application thereof, relates to the technical field of preparation and application of molecular sieve-based monolithic catalysts, and specifically relates to a monolithic catalyst with pure phase and high denitration performance which is prepared by isomorphic silicon-aluminum type ERI seed induction and a simple one-pot hydrothermal method on a cheap cordierite support. The method can incorporate Cu species into the molecular sieve framework as an active component in a hydrothermal process, thereby avoiding the problems of limited active sites and low loading of the catalyst. The catalyst can be applied to selective catalytic reduction of NO by ammonia x and can achieve a denitration efficiency of more than 90% in a temperature range of 200-500 DEG C, has excellent H2O resistance and SO2 resistance, and is suitable for catalytic denitration in various environments such as coke oven gas and diesel engine exhaust.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of preparation and application of molecular sieve-based monolithic catalyst materials, and particularly relates to a Cu-based SAPO-17 monolithic catalyst, a preparation method and application thereof. BACKGROUND

[0002] NH3-SCR technology is currently the mainstream means for eliminating NOx. Small-pore molecular sieve catalysts have good hydrothermal stability, low-temperature catalytic activity and a wide active temperature conversion window, and thus exhibit excellent NOx catalytic efficiency in the denitration process, and thus become a highly potential NH3-SCR catalytic material. x x

[0003] SAPO-17 is a phosphorus-aluminum type molecular sieve with an Erionite (ERI) topological structure, which is formed by a four-membered ring and a double six-membered ring to form a three-dimensional eight-membered ring elliptical channel structure, and has an average effective pore size of 0.36 nm, which is close to that of the commercialized small-pore molecular sieve SSZ-13 (0.38 nm). Generally, SAPO-17 needs to be prepared by a hydrothermal synthesis method in an organic template system containing piperidine, cyclohexylamine, quinuclidine and other small-ring amines, and an intermediate phase is often formed in the synthesis process. Lohse et al. (Zeolites, 13 (1993) 549) and Zhou Rongfei (J Membr Sci, 520 (2016) 507) confirmed that SAPO-5 (AFI), SAPO-35 (LEV), SAPO-34 (CHA) and other impurity phases are easily generated in the target product. At the same time, the synthesis period of SAPO-17 is relatively long. Therefore, the harsh synthesis conditions of SAPO-17 make the related literature reports rare. In addition, the SAPO-17 molecular sieve in these literature reports is mainly applied as a catalyst, an adsorbent and a membrane material in the industrial catalysis, adsorption and separation fields such as methanol-to-light olefin (MTO) and gas separation. Froment et al. (Res Financial Mark, 9 (1992) 1) found that SAPO-17 has a mild acidity and a high selectivity for the conversion of methanol to light olefins, and thus is widely used in the MTO reaction. However, the SAPO-17 molecular sieve is rarely used in the field of NH3-SCR denitration. ​​Acid centers, suitable for catalyzing the conversion of methanol to light olefins. Xu Jun (Tianjin Chemical Industry, 30 (2016) 17) and Liu Songlin (Petroleum Chemical Industry, 51 (2022) 1263) and others investigated the influence of the silicon-aluminum ratio on the morphology and acid properties of SAPO-17 molecular sieves. After MTO testing, it was found that SAPO-17 had excellent catalytic performance and had potential commercial application value. Zhou Rongfei et al. (Micropor Mesopor Mater, 263 (2018) 11) obtained AlPO-17 and SAPO-17 membranes by seed induction method, and found that the prepared membranes showed high CO2 permeability and selectivity in CO2 / CH4 and CO2 / N2 separation. However, there are few reports on SAPO-17 molecular sieves used in NH3-SCR reactions.

[0004] Recently, Zhu et al. (J Catal, 391 (2020) 346) reported the high-temperature rapid synthesis of high-silicon ERI-type molecular sieves (silicon-aluminum type) with the same structure as SAPO-17. By ion exchange method, copper ions were doped into this molecular sieve. The Cu-ERI molecular sieve showed very high activity in NH3-SCR, even comparable to the catalytic performance of Cu-SSZ-13. Although the introduction of Cu active species into the molecular sieve by ion exchange is the most common method, the catalyst obtained by this method has uneven distribution of active sites, low loading capacity, and complicated process steps, resulting in low catalytic activity of the catalyst and large application limitations. Therefore, it is a key problem to be solved to develop a simple and efficient preparation method of Cu-SAPO-17 denitration catalyst materials.

[0005] To improve the catalytic activity of NH3-SCR catalyst, researchers have enhanced the reducibility of copper species by adjusting the loading amount, positioning in the molecular sieve framework, and dispersion. Ren et al. (Chem Commun, 47 (2011) 9789) designed a cheap, non-toxic and easily available copper amine complex (Cu-TEPA) as a new type of template for one-step hydrothermal synthesis of Cu-SSZ-13 molecular sieve catalyst. Compared with the traditional ion exchange method, Cu-TEPA as a template not only greatly reduces the cost of catalyst preparation, but also provides a large amount of active copper species. The prepared catalyst has high copper content and good dispersion, and has excellent denitration performance. On this basis, Zhong et al. (Chem Eng J, 420 (2021) 130425) synthesized Cu-SAPO-34 / SiC monolithic catalytic membrane by one-pot method, which solved the problem of metal dispersion and realized the purpose of removing NO and dust. Inspired by this, developing new monolithic catalysts is an effective way to solve the above problems. Monolithic NH3-SCR catalysts are rarely reported, and generally use coating or impregnation methods to cover the active component layer on the carrier (Appl Catal B: Environ, 187 (2016) 419). The binding force between the active layer and the carrier is weak; and the existing monolithic catalysts have a reaction temperature above 200℃, and further research is needed to apply them to low-temperature NH3-SCR. Therefore, growing a layer of copper-based molecular sieve membrane with catalytic performance on the surface of the carrier is the key to solving the above problems. Generally, seed layer induced synthesis method can obtain molecular sieve membrane with high crystallinity and high purity. In our previous work, we have successfully obtained silica-alumina ERI type molecular sieve (Mater Lett, 260 (2020) 126934 and Chinese invention patent ZL201910036344.0). Therefore, it is a simple and easy way to hydrothermally synthesize copper-based SAPO-17 molecular sieve membrane layer catalyst on the cordierite support by seed induction. SUMMARY

[0006] The present application aims to at least solve one of the technical problems existing in the prior art, and provide a molecular sieve-based monolithic catalyst for efficient NH3-SCR denitration and a preparation method thereof.

[0007] The technical solution of the present application is as follows:

[0008] A preparation method of a Cu-based SAPO-17 monolithic catalyst, comprising the following steps:

[0009] S1: Aluminum sec-butoxide is dissolved in tetraethylammonium hydroxide (TEAOH) to form an aluminum source. A silicon source is added dropwise to the aluminum source and stirred. After aging in an oil bath at 80–95°C for 18–24 hours, potassium hydroxide (KOH) solution and hexamethylammonium bromide (C) are added sequentially. 12 H 30 The Br2N2) solution was thoroughly mixed, and the reaction was carried out at 150-175℃ for 24-120 hours to obtain seed crystals; the obtained seed crystals were then prepared into an impregnation solution.

[0010] S2: Cu 2+ The copper amine complex was obtained by mixing the source and tetraethylenepentamine, and then mixed with cyclohexylamine (CHA) in sequence. The mixture was then poured into a mixture of aluminum isopropoxide and phosphoric acid and stirred at room temperature to form a gel.

[0011] S3: The cordierite support is immersed in the impregnation solution, removed, and then placed in the gel obtained in step S2. Finally, it is prepared hydrothermally in a reaction vessel.

[0012] As a preferred embodiment of the present invention, in step S1, the molar ratio of the obtained seed crystal sol is SiO2:0.03Al2O3:(0.08~0.10)KOH:0.82TEAOH:(0.12~0.15)C 12 H 30 Br2N2:25H2O.

[0013] As a preferred embodiment of the present invention, in step S1, the seed crystal is a nano-sized particle with a particle size of 200-300 nm.

[0014] As a preferred embodiment of the present invention, in step S2, the molar ratio of the obtained gel is (0.01-0.1) Cu-TEPA:1Al2O3:1.1P2O5:0.9CHA:45H2O.

[0015] As a preferred embodiment of the present invention, in step S2, the mixing of the copper source and tetraethylenepentamine specifically involves stirring for 2 hours to form a copper-amine complex.

[0016] As a preferred embodiment of the present invention, in step S2, the molar ratio of the copper amine complex is n(Cu-TEPA) / n(Al2O3) = 0.01 to 0.1.

[0017] As a preferred embodiment of the present invention, in step S3, the concentration of the impregnation solution is 0.5-2wt%, the number of impregnations is 1-4, and the impregnation time for each impregnation is 30-90s.

[0018] As a preferred embodiment of the present invention, in step S3, the preparation method is a one-step hydrothermal synthesis method, the hydrothermal temperature is 190°C, and the synthesis time is 12-48h.

[0019] The application further discloses the Cu-based SAPO-17 monolithic catalyst prepared by the preparation method.

[0020] The application further discloses application of the Cu-based SAPO-17 monolithic catalyst as described above in selective catalytic reduction of NO x by ammonia.

[0021] The application has the following beneficial effects:

[0022] 1. The ERI type seed crystal prepared by the application is nanoscale crystal (200-300 nm) obtained through oil bath oscillation aging and crystallization, has an elliptical shape and uniform particle size, and has a simple preparation process and is convenient for industrial mass production.

[0023] 2. The application provides a preparation method of a Cu-based SAPO-17 monolithic catalyst, that is, a one-pot method is used to quickly grow a pure-phase and continuous SAPO-17 molecular sieve membrane layer on a cheap cordierite support as a catalyst, compared with related reported methods, the preparation process is greatly reduced, and the method has the advantages of simple process, low cost and good repeatability.

[0024] 3. The synthesis sol of the Cu-based SAPO-17 monolithic catalyst prepared by the application is a mixed gel containing Cu-TEPA, Cu-TEPA is introduced into the synthesis sol to introduce active Cu species, and the catalyst is loaded on the cordierite support to improve the denitration performance.

[0025] 4. The Cu-based SAPO-17 monolithic catalyst has high catalytic performance, has excellent catalytic performance, a wide catalytic activity window and H2O and SO2 resistance in the denitration test, and can be more effectively applied to a coke oven gas and a diesel engine tail gas aftertreatment system. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 (a) is an XRD spectrum of the seed crystal prepared in Example 1 of the application, and (b) is an SEM image of the seed crystal;

[0027] Figure 2 (a) is a standard diffraction peak of the SAPO-17 molecular sieve, (b) is a characteristic peak of the cordierite support, and (c), (d) and (e) are XRD spectra of the Cu-SAPO-17 / cordierite monolithic catalysts prepared by using 0.5wt%, 1.0wt% and 2.0wt% impregnation liquid concentrations, respectively;

[0028] Figure 3The catalytic activity diagrams of Cu-SAPO-17 / cordierite monolithic catalysts prepared with different seed crystal impregnation liquid concentrations of Examples 2-4 and Comparative Example 1 of the present application, (a) is 0.5wt%, (b) is 1.0wt%, (c) is 2.0wt%, and (d) is the NH3-SCR activity diagram of the Cu-SAPO-17 molecular sieve catalyst of Comparative Example;

[0029] Figure 4 The SEM diagrams of Cu-SAPO-17 / cordierite monolithic catalysts synthesized with different n(Cu-TEPA) / n(Al2O3) ratios of Examples 5-6 of the present application, (a, b) n(Cu-TEPA) / n(Al2O3) = 0.05, (c, d) n(Cu-TEPA) / n(Al2O3) = 0.01, and (e, f) n(Cu-TEPA) / n(Al2O3) = 0.1;

[0030] Figure 5 The XRD diagrams of Cu-SAPO-17 / cordierite monolithic catalysts synthesized with different n(Cu-TEPA) / n(Al2O3) ratios of Examples 5-6 of the present application, (a) is the standard diffraction peak of SAPO-17 molecular sieve, (b) is the characteristic peak of the cordierite support, (c) and (d) are respectively the XRD spectra of the monolithic catalysts prepared with n(Cu-TEPA) / n(Al2O3) ratios of 0.01 and 0.1;

[0031] Figure 6 The NH3-SCR diagrams of Cu-SAPO-17 / cordierite monolithic catalysts synthesized with different n(Cu-TEPA) / n(Al2O3) ratios of Examples 5-6 of the present application, (a) and (b) are respectively the catalytic activity diagrams of the monolithic catalysts prepared with n(Cu-TEPA) / n(Al2O3) ratios of 0.01 and 0.1;

[0032] Figure 7 The NH3-SCR activity diagrams of Cu-SAPO-17 / cordierite obtained in the present application in (a) H2O-containing and (b) SO2-containing simulated flue gas systems;

[0033] Figure 8 The (a) XRD and (b) SEM diagrams of Cu-SAPO-17 powder catalyst obtained in Comparative Example 1. DETAILED DESCRIPTION

[0034] The application is committed to Cu-based high-efficiency NH3-SCR catalyst research from the carrier and preparation method of the catalyst, and a Cu-SAPO-17 / cordierite monolithic catalyst with high crystallinity and high deNOx catalytic performance is obtained by replacing the Cu species into the molecular sieve material through a one-pot method, so that the process flow of preparing the Cu-modified SAPO-17 is greatly reduced.

[0035] The first aspect of the object of the application provides a preparation method of a Cu-based SAPO-17 monolithic catalyst, comprising the following steps:

[0036] S1, self-prepared seed solution: aluminum sec-butoxide is dissolved in tetraethylammonium hydroxide (TEAOH) to form an aluminum source, and then silicon source is added dropwise into the aluminum source, and then the mixture is poured into a PP bottle and stirred, and then KOH solution, C 12 H 30 Br2N2 solution is fully mixed, and finally poured into a stainless steel reaction kettle for reaction at 150-175 DEG C for 24-120 h to obtain the seed crystal. The molar ratio of the obtained seed crystal sol is SiO2:0.03Al2O3:(0.08-0.10)KOH:0.82TEAOH:(0.12-0.15)C 12 H 30 Br2N2:25H2O. And the obtained silicon-aluminum type ERI type molecular sieve is prepared as a seed solution.

[0037] S2, synthesis of gel preparation: Cu 2+ source and TEPA are mixed to obtain a copper amine complex, and then cyclohexylamine is sequentially mixed, and then poured into a mixture of aluminum isopropyl alcohol and phosphoric acid, and then stirred at room temperature to prepare a gel, and the obtained ratio is (0.01-0.1)Cu-TEPA:1Al2O3:1.1P2O5:0.9CHA:45H2O.

[0038] S3, monolithic catalyst preparation: first, the seed crystal obtained in step S1 is prepared into an impregnation solution and loaded on a cordierite support (using an impregnation method), and then placed in the gel obtained in step S2, and finally the Cu-SAPO-17 / cordierite monolithic catalyst is prepared in a reaction kettle.

[0039] The application provides a preparation method of a Cu-based SAPO-17 monolithic catalyst, and a monolithic catalyst with excellent denitration performance is prepared on a cheap cordierite support by one-pot hydrothermal method.

[0040] Preferably, the crystal seeds in step S1 are nano-sized particles with a particle size of 200-300 nm.

[0041] Preferably, the Cu 2+ The Cu source (CuSO4 or Cu(NO3)2) and TEPA are mixed, and a copper amine complex is formed by stirring for 2 h.

[0042] Preferably, the molar ratio in the copper amine complex in step S2 is n(Cu-TEPA) / n(Al2O3) = 0.05-0.1.

[0043] Preferably, the preparation method in step S3 is one-pot method.

[0044] In a second aspect of the application, a Cu-based SAPO-17 monolithic catalyst is provided, which is prepared according to any one of the above preparation methods.

[0045] In a third aspect of the application, a use of the Cu-based SAPO-17 monolithic catalyst in denitration is provided.

[0046] The technical solutions in the embodiments of the application will be described clearly and completely below with reference to the drawings in the embodiments of the application. Obviously, the described embodiments are only some of the embodiments of the application, rather than all the embodiments of the application. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the application.

[0047] The stirring speed in the preferred embodiment of the present application is 350r, the centrifugal speed is 10000r / min, the time is 6min, and the volume of the stainless steel reactor is 100mL.

[0048] Example 1

[0049] The molar ratio of the oxides of the components of the prepared crystal seeds is SiO2:0.03Al2O3:0.10KOH:0.82TEAOH:0.15C 12 H 30 Br2N2:25H2O. The experimental steps are as follows: aluminum isopropylate is added to TEAOH to form an aluminum source, and then silica sol is added dropwise to form a mixed solution, which is aged in an oil bath oscillation kettle at 90℃ for 20h. After aging, the solution is cooled to room temperature, and then KOH solution and hexamethonium bromide solution are added in sequence. After being fully stirred, the solution is poured into a stainless steel reactor, and then crystallized at 150℃ for 120h to obtain the final product. Finally, the obtained product is centrifuged to neutral, and then dried at 80℃ for 12h to obtain ERI molecular sieve.

[0050] Characterization results: Figure 1 The XRD characterization diagram of the product of the present embodiment is shown in (a) of FIG. 1, which has obvious ERI characteristic diffraction peaks, and no other impurity crystal phase, indicating that the molecular sieve prepared in the present embodiment is a pure phase ERI type molecular sieve. Figure 1 (b) of FIG. 1 shows the SEM characterization diagram of the synthesized ERI type molecular sieve. It can be found from the SEM diagram that the obtained molecular sieve is elliptical, and the particle size is about 200-300nm. Figure 1

[0051] Example 2

[0052] In deionized water, tetraethylenepentamine and CuSO4 are added, and after being fully stirred for 2h, Cu-TEPA is formed. Then cyclohexylamine is added and stirred for 2h to form a mixed solution. Finally, the mixed solution is poured into deionized water containing phosphoric acid and aluminum isopropylate, and after being fully stirred, a mixed sol is formed. The molar ratio of the oxides of the components is 0.05Cu-TEPA:1Al2O3:1.1P2O5:0.9CHA:45H2O. The crystal seeds obtained in Example 1 are configured into an impregnation solution with a mass fraction of 0.5wt%, and then cordierite is immersed in the impregnation solution for 90s to load the crystal seeds, and then dried in a blast drying oven at 80℃ for 1h. Finally, the above crystal seed-loaded cordierite and the mixed sol are placed in a stainless steel reactor at 190℃ for 24h. The obtained monolithic catalyst is washed with water to neutral, and then dried in a blast drying oven at 80℃ for standby.

[0053] Characterization results: Figure 2 ​(a) is the diffraction peak of standard SAPO-17 molecular sieve, (b) is the diffraction peak of the cordierite support, (c) is the XRD spectrum of the monolithic catalyst prepared in the seed solution, the spectrum has obvious SAPO-17 characteristic diffraction peaks and cordierite support diffraction peaks, and no other impurity crystal phase, indicating that the product prepared is pure SAPO-17 monolithic catalyst. The catalyst was tested for denitration, and the catalytic activity is shown in Figure 3 (a). It is found that the NO x conversion is poor at low temperature, and the catalytic activity is good at temperature > 400℃.

[0054] Example 3

[0055] Cu-TEPA was formed by adding tetraethylenepentamine and CuSO4 into deionized water and stirring for 2h, and then cyclohexylamine was added and stirred for 2h to form a mixed solution. Finally, the mixed solution was poured into deionized water containing phosphoric acid and aluminum isopropoxide, and after stirring, a mixed sol was formed. The molar ratio of the oxides of each component was 0.05 Cu-TEPA: 1 Al2O3: 1.1 P2O5: 0.9 CHA: 45 H2O. The seed crystals obtained in Example 1 were configured into an impregnation solution with a mass fraction of 1.0 wt%, and the cordierite was immersed in the impregnation solution for 60s to load the seed crystals, and then dried in a blast oven at 80℃ for 1h. Finally, the cordierite loaded with seed crystals and the mixed sol were placed in a stainless steel reaction kettle at 190℃ for 24h. The obtained monolithic catalyst was washed with water until neutral, and then dried in a blast oven at 80℃ for standby.

[0056] Characterization results: Figure 2 (d) is the XRD characterization spectrum of the obtained monolithic catalyst, the spectrum has obvious SAPO-17 and cordierite characteristic diffraction peaks, and no other impurity crystal phase, indicating that the catalyst prepared in this example is a standard SAPO-17 molecular sieve. The monolithic catalyst was tested for denitration, and the activity graph is shown in Figure 3 (b). It is found that it has 100% NO x conversion at 200-500℃, and the conversion at 500℃ is also more than 90%, proving that it has excellent denitration performance. Figure 4 (a) and (b) of the monolithic catalyst synthesized in this example represent the SEM characterization spectrum of the monolithic catalyst, and it can be found that the surface morphology of the obtained monolithic catalyst is a film layer formed by the close packing of cubic crystal blocks, and there are spherical bodies formed by the agglomeration of needle-shaped grains on the film layer, and the molecular sieve film layer is about 20μm thick. It is proved that the self-made seed crystals can successfully induce SAPO-17 molecular sieve.

[0057] Example 4

[0058] Cu-TEPA was formed by adding tetraethylenepentamine and CuSO4 into deionized water and stirring for 2 h, and then cyclohexylamine was added and stirred for 2 h to form a mixed solution. Finally, the mixed solution was poured into deionized water containing phosphoric acid and aluminum isopropyl alcohol, and a mixed sol was formed after stirring. The ratio of the oxides of the components (molar ratio) was 0.05 Cu-TEPA: 1 Al2O3: 1.1 P2O5: 0.9 CHA: 45 H2O. The seed crystals obtained in Example 1 were configured into an impregnation solution with a mass fraction of 2.0 wt%, and the cordierite was immersed in the impregnation solution for 30 s to load the seed crystals, and then dried in a blast oven at 80°C for 1 h. Finally, the cordierite loaded with the seed crystals and the mixed sol were placed in a stainless steel reaction kettle at 190°C for 24 h. The obtained monolithic catalyst was washed with water until neutral, and then dried in a blast oven at 80°C for standby use.

[0059] Characterization results: Figure 2 In (e), there are obvious SAPO-17 characteristic diffraction peaks and cordierite support diffraction peaks, and no other impurity crystal phases, indicating that the prepared product is a pure SAPO-17 monolithic catalyst. The catalyst was tested for denitration, and the activity was as shown in Figure 3 As shown in (c), the NO conversion rate can reach 100% in the temperature range of 250-400°C, but the catalytic activity decreases rapidly when the temperature is higher than 400°C.

[0060] Example 5

[0061] Cu-TEPA was formed by adding tetraethylenepentamine and CuSO4 into deionized water and stirring for 2 h, and then cyclohexylamine was added and stirred for 2 h to form a mixed solution. Finally, the mixed solution was poured into deionized water containing phosphoric acid and aluminum isopropyl alcohol, and a mixed sol was formed after stirring. The ratio of the oxides of the components (molar ratio) was 0.01 Cu-TEPA: 1 Al2O3: 1.1 P2O5: 0.9 CHA: 45 H2O. The seed crystals obtained in Example 1 were configured into an impregnation solution with a mass fraction of 1.0 wt%, and the cordierite was immersed in the impregnation solution for 90 s to load the seed crystals, and then dried in a blast oven at 80°C for 1 h. Finally, the cordierite loaded with the seed crystals and the mixed sol were placed in a stainless steel reaction kettle at 190°C for 24 h. The obtained monolithic catalyst was washed with water until neutral, and then dried in a blast oven at 80°C for standby use.

[0062] Characterization results: Figure 5 In (a), it is the diffraction peak of the standard SAPO-17 molecular sieve, (b) is the diffraction peak of the cordierite support, and (c) is the XRD spectrum of the monolithic catalyst prepared with n(Cu-TEPA) / n(Al2O3) of 0.01, which only has SAPO-17 characteristic diffraction peaks and cordierite support diffraction peaks, and no other impurity crystal phases, indicating that the prepared product is a pure SAPO-17 monolithic catalyst. Figure 4(c, d) are the SEM crystal morphology of the surface and section of the catalyst, from Figure 4 (c) it can be seen that the crystal is made up of cubic block grains of different sizes, and the film thickness is 30 μm. The catalyst was tested for denitration, and the activity is shown in Figure 5 (a) it can be seen that the catalyst has no performance at low temperature and only has good denitration activity at high temperature (400-600°C).

[0063] Example 6

[0064] Cu-TEPA was formed by adding tetraethylenepentamine (TEPA) and CuSO4 into deionized water and stirring for 2 h, and then cyclohexylamine was added and stirred for 2 h to form a mixed solution. Finally, the mixed solution was poured into deionized water containing phosphoric acid and aluminum isopropyl alcohol, and stirred thoroughly to form a mixed sol. The molar ratio of the oxides of each component was 0.1 Cu-TEPA: 1 Al2O3: 1.1 P2O5: 0.9 CHA: 45 H2O. The seed crystals obtained in Example 1 were used to prepare an impregnation solution with a mass fraction of 1.0 wt%, and the cordierite was immersed in the impregnation solution for 60 s to load the seed crystals, and then dried in a blast oven at 80°C for 1 h. Finally, the cordierite loaded with seed crystals and the mixed sol were placed in a stainless steel reaction kettle and reacted at 190°C for 48 h. The obtained monolithic catalyst was washed with water until neutral, and then dried in a blast oven at 80°C for standby.

[0065] Characterization results: Figure 5 (d) only SAPO-17 characteristic diffraction peaks and cordierite support diffraction peaks were observed, and no other impurity crystal phases were observed, indicating that the product prepared was a pure SAPO-17 monolithic catalyst. The Figure 4 (e, f) SEM observation showed that the surface morphology of the catalyst was a close-packed rod-shaped crystal grain with a size of 50 μm, and the film thickness was 25 μm. The catalyst was tested for denitration, and the activity is shown in Figure 6 (b) it can be seen that compared with Example 2, the catalytic activity window is in a narrower medium-high temperature range (250-400°C), which may be due to the high content of Cu species in the catalyst inhibiting the high-temperature catalytic activity of the catalyst.

[0066] Example 7

[0067] Cu-TEPA was formed by adding tetraethylenepentamine and Cu(N03)2into deionized water and stirring for 2 h, and then cyclohexylamine was added and stirred for 2 h to form a mixed solution. Finally, the mixed solution was poured into deionized water containing phosphoric acid and aluminum isopropyl alcohol, and a mixed sol was formed after stirring. The ratio of each component in oxide form (molar ratio) was 0.05 Cu-TEPA: 1 Al203: 1.1 P205: 0.9 CHA: 45 H20. The seed crystals obtained in Example 1 were configured into an impregnation solution with a mass fraction of 1.0 wt%, and the cordierite was immersed in the impregnation solution for 90 s to load the seed crystals, and then dried in a blast oven at 80°C for 1 h. Finally, the cordierite loaded with the seed crystals and the mixed sol were placed in a stainless steel reaction kettle at 190°C for 24 h. The obtained monolithic catalyst was washed with water until neutral, and then dried in a blast oven at 80°C for standby.

[0068] Characterization results: In order to test the resistance of the catalyst to H20 and SO2, the H20 and SO2 resistance stability tests were carried out. Figure 7 and Figure 8 The figure shows the NH3-SCR performance of the obtained Cu-SAPO-17 / cordierite monolithic catalyst in a simulated flue gas system containing H20 and SO2. It can be seen from the figure that the addition of water throughout the process has no effect on the activity of the catalyst, and after the introduction of SO2 for 3.5 h, the NO x conversion rate of the catalyst begins to decrease, and only decreases to 94% at 7 h; after the removal of SO2, the activity of the catalyst is restored after 1 h. This indicates that the Cu-SAPO-17 / cordierite monolithic catalyst has excellent water and sulfur resistance stability.

[0069] Comparative Example 1

[0070] Cu-TEPA was formed by adding tetraethylenepentamine and CuSO4into deionized water and stirring for 2 h, and then cyclohexylamine was added and stirred for 2 h to form a mixed solution. Finally, the mixed solution was poured into deionized water containing phosphoric acid and aluminum isopropyl alcohol, and a mixed sol was formed after stirring. The ratio of each component in oxide form (molar ratio) was 0.05 Cu-TEPA: 1 Al203: 1.1 P205: 0.9 CHA: 45 H20. 0.5 wt% of the seed crystals obtained in Example 1 were added to the sol, and crystallization was carried out at 190°C for 24 h. Finally, the obtained product was boiled, centrifuged, dried, and ground for standby.

[0071] Characterization results: Figure 8 The XRD and SEM figures of the synthesized Cu-SAPO-17 catalyst in powder form are shown, and it can be seen from the comparison with the standard characteristic peaks that the product is a SAPO-17 molecular sieve. No diffraction peaks of Cu species were found in the XRD spectrum, which may be due to the uniform distribution of Cu species in the crystal. The denitration test was carried out on the sample, and the results are shown in Figure 3(d) as shown, the highest conversion rate of the catalyst is 55% at 350°C. It is far lower than the NH3-SCR catalytic performance of the monolithic catalyst.

[0072] The catalytic performance test conditions of the above-mentioned examples 2-7 monolithic catalysts are: 500 ppm NO, 500 ppm NH3, 5% volume of O2, and N2 as the reaction equilibrium gas. The total flow rate of the reaction gas is fixed at 100 mL min -1 , and the space velocity (WHSV) is 60,000 h -1 For the comparative example 1, the powder catalyst is pressed into granules and sieved, the catalyst with a particle size of 40-60 mesh is selected, and 0.1 g of the catalyst sample is loaded into the U-shaped reaction tube, and then the test is carried out according to the above test conditions.

[0073] The above-mentioned examples only express the preferred embodiments of the present application, and the description is more specific and detailed, but it should not be understood as a limitation on the scope of the patent of the present application. It should be noted that for ordinary skilled persons in the art, other various corresponding changes and deformations can be made according to the above-described technical solutions and concepts, and all these changes and deformations should belong to the protection scope of the claims of the present application.

Claims

1. A method for preparing a Cu-based SAPO-17 monolithic catalyst, characterized in that, Includes the following steps: S1: Aluminum sec-butoxide is dissolved in tetraethylammonium hydroxide (TEAOH) to form an aluminum source. A silicon source is added dropwise to the aluminum source and stirred. After aging in an oil bath at 80-95 °C for 18-24 h with shaking, potassium hydroxide (KOH) solution and hexamethylammonium bromide (C) are added sequentially. 12 H 30 The Br2N2 solution was thoroughly mixed, and the reaction was carried out at 150~175℃ for 24~120 h to obtain seed crystals, and the obtained seed crystals were prepared into an impregnation solution. S2: Cu 2+ The source and tetraethylenepentamine (TEPA) were mixed to obtain Cu-TEPA copper amine complex, which was then mixed with cyclohexylamine (CHA) in sequence and poured into a mixture of aluminum isopropoxide and phosphoric acid. The mixture was stirred at room temperature to form a gel. S3: The cordierite support is immersed in the impregnation solution, removed, and then placed in the gel obtained in step S2. Finally, it is prepared hydrothermally in a reaction vessel. In step S1, the molar ratio of the sol-gel of the obtained seed crystals is SiO2 : 0.03, Al2O3 : (0.08~0.10), KOH : 0.82, TEAOH : (0.12~0.15), C. 12 H 30 Br2N2 :25 H2O.

2. The method for preparing the Cu-based SAPO-17 monolithic catalyst according to claim 1, characterized in that, In step S1, the seed crystals are nano-sized particles with a particle size of 200~300 nm.

3. The method for preparing the Cu-based SAPO-17 monolithic catalyst according to claim 1, characterized in that, In step S2, the molar ratio of the resulting gel (0.01-0.1) is Cu-TEPA : 1 Al2O3 : 1.1 P2O5 : 0.9 CHA : 45 H2O.

4. The method for preparing the Cu-based SAPO-17 monolithic catalyst according to claim 1, characterized in that, In step S2, the Cu 2+ The source and tetraethylenepentamine were mixed and stirred for 2 hours to form a copper amine complex.

5. The method for preparing the Cu-based SAPO-17 monolithic catalyst according to claim 1, characterized in that, In step S2, the molar ratio of the copper amine complex is: n (Cu-TEPA) / n (Al2O3) = 0.01~0.

1.

6. The method for preparing the Cu-based SAPO-17 monolithic catalyst according to claim 1, characterized in that, In step S3, the concentration of the impregnation solution is 0.5~2 wt%, the number of impregnations is 1~4, and the impregnation time for each impregnation is 30~90 s.

7. The method for preparing the Cu-based SAPO-17 monolithic catalyst according to claim 1, characterized in that, In step S3, the preparation method is a one-step hydrothermal synthesis method, with a hydrothermal temperature of 190℃ and a synthesis time of 12~48 h.

8. A Cu-based SAPO-17 monolithic catalyst, characterized in that, It is prepared by any one of claims 1 to 7.

9. A Cu-based SAPO-17 monolithic catalyst as described in claim 8 for the selective catalytic reduction of NO by ammonia. x Applications on [platform name].

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