A copper-based SSZ-39 molecular sieve catalyst, its preparation method and application

Abstract

The present invention discloses a copper-based SSZ-39 molecular sieve catalyst, its preparation method and application, belonging to the technical field of molecular sieves. The catalyst includes a carrier, the carrier is SSZ-39 molecular sieve, the active component is copper, and the promoter components are niobium and manganese; the catalyst is a cuboid with a grain side length of 0.4-0.6 μm and a height of 0.1-0.2 μm; based on the total mass of the catalyst, the mass fraction of the active component copper is 2.42-2.72 wt%, the mass fraction of the promoter component niobium is 0.27-0.37 wt%, and the mass fraction of the promoter component manganese is 1.21-1.33 wt%. The catalyst of the present invention has very excellent low-temperature denitration activity, and the lowest ignition temperature T 50 is lower than 90 °C, and the NO conversion rate reaches more than 90% in a wide temperature range of 128-500 °C.

Description

Technical Field

[0001] The present invention relates to a copper-based SSZ-39 molecular sieve catalyst, a preparation method thereof, and an application thereof, and belongs to the technical field of molecular sieves. Background Art

[0002] With the progress of society, it has become an urgent task to control air pollution to protect the blue sky and white clouds in our country. Among them, nitrogen oxides (NO x ) are one of the main air pollutants. It once triggered the infamous Los Angeles photochemical smog incident, causing great casualties and economic losses. At the same time, its large emissions will also cause many serious environmental problems such as acid rain and ozone depletion. Therefore, our country has formulated NO x emission standards for stationary sources and mobile sources. That is, according to the requirements of the national standard GB-13223-2011, the NO x emissions in the flue gas of newly built power plants and natural gas furnaces shall not exceed 100 mg / m 3 , and the NO x emissions in natural gas turbine units shall not exceed 50 mg / m 3 . In addition, according to the national standard GB-18352.6-2016, our country will implement more stringent motor vehicle exhaust emission standards in July 2023 (adjusted from 60 mg / km in 2020 to 35 mg / km). Therefore, the development of an efficient and stable denitration catalyst can bring great benefits to environmental protection and social development in our country.

[0003] Ammonia selective catalytic reduction technology (NH3-SCR) has become the most popular denitration technology in the market at present because of its wide reaction window temperature, high stability and selective conversion efficiency. The first batch of commercial NH3-SCR catalysts are vanadium-based oxide catalysts, but due to their poor low-temperature denitration performance, high-temperature stability and biological toxicity, they can no longer meet the increasingly strict environmental protection requirements of various countries. Copper-based small-pore molecular sieve-based NH3-SCR catalysts have attracted the attention of many researchers due to their large specific surface area, non-toxicity, wide reaction activity window, excellent high-temperature hydrothermal stability, and good anti-poisoning ability. At present, the small-pore molecular sieve catalysts used for NH3-SCR catalysis are mainly Cu-SSZ-13 molecular sieves with CHA configuration and Cu-SSZ-39 molecular sieves with AEI configuration. Among them, Cu-SSZ-13 molecular sieves have been used for the treatment of diesel vehicle exhaust in many countries and regions because of their excellent denitration performance. However, compared with Cu-SSZ-13 molecular sieves, the former has a more complex mirror arrangement of adjacent double six-membered rings than the parallel arrangement of adjacent double six-membered rings in the latter. Therefore, Cu-SSZ-39 has more excellent denitration catalytic activity and hydrothermal stability, which makes Cu-SSZ-39 have greater advantages as an NH3-SCR catalytic material.

[0004] Although Cu-SSZ-39 molecular sieves have many advantages for NH3-SCR catalytic reactions, the current NH3-SCR window temperature of Cu-SSZ-39 mainly focuses on 200°C to 500°C, and the denitration effect of low-temperature flue gas generated by cold start and long-term low-speed operation of fixed sources and mobile sources is not good, resulting in a more complex treatment system and poor effect. Therefore, many researchers have improved the low-temperature denitration performance of Cu-SSZ-39 by introducing a second metal element. Patent CN 114602544 A prepared a CHA-type molecular sieve containing metal oxides, rare earth elements and copper elements by multiple ion exchange methods and excessive impregnation, which has good low-temperature denitration performance. Patent CN107661776A discloses a method for preparing a Cu, Ag bimetal-containing SAPO molecular sieve by ion exchange. The prepared Cu, Ag bimetal-containing SAPO molecular sieve has better low-temperature activity compared with the SPAO molecular sieve with a single metal element. Patent CN114247467A discloses the preparation of a multi-metal modified USY-type molecular sieve catalyst by impregnation method, which broadens the reaction window temperature of denitration. However, most ion exchange methods require multiple ion exchanges, repeated washing, drying and calcination, with a long cycle, high energy consumption and a large amount of waste liquid. The metal species of the catalyst prepared by the impregnation method are prone to agglomeration and poor dispersion, which limits the improvement of the catalytic activity of the catalyst. Summary of the Invention

[0005] The object of the present invention is, in view of the above situation, to provide a copper-based SSZ-39 molecular sieve catalyst, which has very excellent low-temperature denitration activity, and the lowest ignition temperature T 50 is lower than 90 °C, and the NO conversion rate reaches more than 90% in a wide temperature range of 128-500 °C.

[0006] Meanwhile, the present invention provides a preparation method of a copper-based SSZ-39 molecular sieve catalyst. This method directionally regulates the location of copper ions through niobium ions, and then manganese is introduced for modification. The whole process is more precisely controllable. This method shortens the hydrothermal crystallization time of the molecular sieve from more than 48 h in the existing method to about 6 h, and increases the specific surface area of the molecular sieve from about 520 m 2 / g to about 625 m 2 / g, and reduces the crystal grain size of the molecular sieve to about 600 nm, which is beneficial to weakening the influence of internal diffusion in the catalyst, strengthening heat and mass transfer in the reaction process, and promoting the occurrence of the reaction.

[0007] Meanwhile, the present invention provides an application of a copper-based SSZ-39 molecular sieve catalyst in selective catalytic reduction denitration.

[0008] To solve the above technical problems, the technical solution adopted by the present invention is as follows:

[0009] A copper-based SSZ-39 molecular sieve catalyst includes a carrier, the carrier is SSZ-39 molecular sieve, the active component is copper, and the promoter components are niobium and manganese; the catalyst is a cuboid with a grain side length of 0.4-0.6 μm and a height of 0.1-0.2 μm; based on the total mass of the catalyst, the mass fraction of the active component copper is 2.42-2.72 wt%, the mass fraction of the promoter component niobium is 0.27-0.37 wt%, and the mass fraction of the promoter component manganese is 1.21-1.33 wt%.

[0010] A preparation method of a copper-based SSZ-39 molecular sieve catalyst includes the following steps:

[0011] Step 1, at 25 °C, first mix a copper source, a niobium source, an amine compound and deionized water to obtain a mixture one, then mix a molecular sieve seed crystal, a template agent and a silicon source to obtain a mixture two, and finally mix the mixture one and the mixture two and age them in a reaction kettle at 30 °C for 1-3 h to obtain an initial gel. The mass ratio of the mixture one to the mixture two is 1:(0.41-1.59); then use microwave-assisted heating to raise the temperature of the reaction kettle to 150-200 °C for hydrothermal crystallization for 6 h; after cooling to room temperature, filter and wash, and dry the filter cake at 80-100 °C for 8-12 h to obtain a crude product;

[0012] Within the first 3 h of hydrothermal crystallization, the microwave hydrothermal synthesis power is 450 - 600 W; within the subsequent 3 h of hydrothermal crystallization, the microwave hydrothermal synthesis power is 300 - 400 W.

[0013] Step 2: Stir the crude product obtained in Step 1, manganese source, ammonium source, and deionized water in a reaction kettle, and perform ion exchange at 70 - 90 °C for 5 - 10 h; after cooling to room temperature, filter, wash, dry the filter cake at 50 - 80 °C for 8 - 10 h, and then calcine at a temperature of 400 - 600 °C for 6 - 12 h to obtain a copper-based SSZ-39 molecular sieve catalyst.

[0014] In Step 1, the mass ratio of the copper source, niobium source, amine compound, and deionized water is 1:(0.11 - 0.20):(0.60 - 1.31):(20 - 50).

[0015] The copper source is one of copper sulfate, copper nitrate, and copper acetate; the niobium source is one of niobium chloride or ammonium oxalate niobate; the amine compound is one or a combination of diethylenetriamine, triethylenetetramine, and tetraethylenepentamine.

[0016] In Step 1, the mass ratio of the molecular sieve seed, template agent, and silicon source is 1:6.53:10.

[0017] The molecular sieve seed is a zeolite seed, and the zeolite seed is one of SSZ-39 molecular sieve, Y molecular sieve, or Beta molecular sieve; the template agent is one of N,N-dimethyl-3,5-dimethylpiperidinium hydroxide or N,N-diethyl-cis-2,6-dimethylpiperidinium hydroxide; the silicon source is one of tetraethyl orthosilicate, silica sol, and sodium silicate.

[0018] In Step 2, the mass ratio of the crude product, manganese source, ammonium source, and deionized water is 1:(0.25 - 0.49):(2.14 - 3.2):40.

[0019] The manganese source is one of manganese nitrate, manganese chloride, and manganese acetate tetrahydrate; the ammonium source is one of ammonium nitrate or ammonium chloride.

[0020] Application of a copper-based SSZ-39 molecular sieve catalyst in selective catalytic reduction denitration.

[0021] The present invention has the following beneficial effects:

[0022] 1. The present invention utilizes niobium ions and copper ions to combine with the above-mentioned amine compounds for coordination, ensuring the stability of the above-mentioned metal ions (niobium ions and copper ions) under the alkaline conditions of molecular sieve crystallization, preventing aggregation to form precipitates, and making their distribution in the molecular sieve system more dispersed. Meanwhile, a metal active precursor similar in size to the cage of SSZ-39 molecular sieve is obtained, which can play a structure-directing role. Therefore, the silicon source and aluminum source (the aluminum source in the present invention comes from molecular sieve seeds) can be better utilized to induce the generation of more single Al sites, which is beneficial to the excellent low-temperature denitrification activity of [Cu(OH)] + -Z species, where Z represents SSZ-39 molecular sieve. In addition, niobium ions with a smaller ionic radius have a greater advantage in preferentially occupying the six-membered rings in SSZ-39 molecular sieve. Therefore, more copper ions will enter the eight-membered rings in SSZ-39 molecular sieve to generate [Cu(OH)] + -Z species. Therefore, the introduction of niobium ions can generate more [Cu(OH)] + -Z species, thereby enhancing the low-temperature denitrification activity of the catalyst. In addition, the introduction of niobium will lead to the generation of some chemisorbed oxygen, which is beneficial to the generation of SCR reaction intermediates and thus beneficial to the improvement of the denitrification catalytic activity of the catalyst.

[0023] 2. The present invention further introduces manganese ions to modify the catalyst to further improve the low-temperature denitrification catalytic activity of the catalyst. Because the rich and variable metal valence states and strong redox ability of manganese are very beneficial to the low-temperature SCR reaction, the introduction of manganese can endow the catalyst with excellent low-temperature denitrification activity under the condition of relatively low Cu content, avoiding the generation of unnecessary copper oxide substances, which is not conducive to the high-temperature catalytic activity of the catalyst. At the same time, manganese ions can undergo electron transfer with [Cu(OH)] + -Z species, enhancing the redox ability of [Cu(OH)] + -Z, thereby reducing the reaction activation energy required for the generation of SCR reaction intermediates. In addition, the strong electrostatic interaction between manganese ions and [Cu(OH)] + -Z enhances the stability of [Cu(OH)] + -Z and can also inhibit the generation of copper oxide species, thereby enhancing the denitrification activity of the catalyst.

[0024] 3. In the prior art, the commonly used method for multi-metal loaded molecular sieve catalysts is the co-ion exchange method, that is, copper and manganese are introduced simultaneously, which will cause competition and exchange between copper and manganese, resulting in greater randomness and uncertainty and unable to control the specific location of copper ions. In the present invention, niobium ions are used to directionally regulate the location of copper ions, and then manganese is introduced for modification, making the whole process more precisely controllable.

[0025] 4. The present invention adopts a microwave-assisted method for the crystallization synthesis process of molecular sieves. Compared with the conventional hydrothermal crystallization method, the present invention shortens the hydrothermal crystallization time of molecular sieves from more than 48 hours to about 6 hours, increases the specific surface area of molecular sieves from about 520 m 2 / g to about 625 m 2 / g, and reduces the crystal grain size of molecular sieves to about 600 nm, which is beneficial to weakening the influence of internal diffusion in the catalyst, strengthening heat and mass transfer in the reaction process, and promoting the occurrence of the reaction.

[0026] 5. The present invention discloses a copper-based SSZ-39 molecular sieve catalyst, which has excellent low-temperature denitration activity. The lowest ignition temperature T 50 is lower than 90 °C, and the NO conversion rate reaches more than 90% in a wide temperature range of 128 - 500 °C. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is the SEM diagram of Example 1 of the present invention;

[0028] Figure 2 The XRD diagrams of the copper-based SSZ-39 molecular sieve catalysts in Examples 1 - 4 are shown;

[0029] Figure 3 The SCR activity test diagrams of the catalysts in Examples 1 - 4 and Comparative Examples 1 - 4 are shown;

[0030] Figure 4 The XRD diagrams of the molecular sieve catalysts in Comparative Examples 1 - 4 are shown. DETAILED DESCRIPTION OF THE INVENTION

[0031] The present invention will be further described in detail below with reference to the drawings and specific examples. The following examples are only used to illustrate the present invention and are not used to limit the scope of the present invention.

[0032] Example 1

[0033] A preparation method of a copper-based SSZ-39 molecular sieve catalyst includes the following steps:

[0034] At 25 °C, first, 2.21 g of copper acetate, 0.32 g of niobium chloride, 1.78 g of triethylenetetramine and 44.2 g of deionized water were mixed to obtain mixture one. Subsequently, 3.6 g of Y zeolite, 23.5 g of N,N-dimethyl-3,5-dimethylpiperidinium hydroxide and 36 g of tetraethyl orthosilicate were mixed to obtain mixture two. Finally, mixture one and mixture two were mixed and aged in a reaction kettle at 30 °C for 2 h to obtain an initial gel. Microwave-assisted heating was used to raise the temperature to 170 °C for hydrothermal crystallization for 6 h. The microwave hydrothermal synthesis power was 500 W in the first 3 h and 350 W in the last 3 h. After cooling to room temperature, filtration and washing were carried out, and the filter cake was dried at 80 °C for 8 h to obtain a crude product.

[0035] 0.98 g of manganese acetate tetrahydrate was weighed and completely dissolved in 80 mL of 1 mol / L ammonium chloride solution. Then, 2 g of the crude product prepared in step 1 was added to the reaction kettle, and after sufficient stirring, ion exchange was carried out at 70 °C for 8 h. After completion and cooling to room temperature, filtration and separation were carried out. The filter cake was washed with deionized water until neutral, dried at 80 °C for 10 h, and calcined at 550 °C for 10 h to obtain a copper-based SSZ-39 zeolite catalyst. The XRD pattern of the prepared copper-based SSZ-39 zeolite catalyst is shown in Figure 2 as follows.

[0036] The low-temperature denitration AEI catalyst of this example was pressed and screened to 20 - 40 mesh, and the contents of each component of the SCR activity test gas were as follows: 500 ppm of NH3, 500 ppm of NO, 5 vol% of O2 and N2 balance gas. The SCR activity test of the catalyst was carried out at a temperature range of 80 - 500 °C, 1 standard atmosphere, and a gas volume space velocity of 60000 h -1 under the conditions, and the SCR activity curve of the AEI zeolite catalyst is shown in Figure 3 as follows.

[0037] After the SCR activity test, the AEI catalyst of this example has very excellent low-temperature denitration activity. The lowest ignition temperature T 50 is 82 °C, and the NO conversion rate reaches 90% in a wide temperature range of 128 - 500 °C. Furthermore, the NO conversion rate reaches 97% in a wide temperature range of 140 - 500 °C, as shown in Figure 1As shown, it is the SEM image of the copper-based SSZ-39 zeolite catalyst obtained in Example 1. The copper-based SSZ-39 zeolite catalyst includes a carrier, the carrier is SSZ-39 zeolite, the active component is copper, and the promoter components are niobium and manganese; the catalyst is a cuboid with a grain side length of 0.4 - 0.6 μm and a height of 0.1 - 0.2 μm; based on the total mass of the catalyst, the mass fraction of the active component copper is 2.53 wt%, the mass fraction of the promoter component niobium is 0.37 wt%, and the mass fraction of the promoter component manganese is 1.24 wt%.

[0038] Application of the copper-based SSZ-39 zeolite catalyst of this example in selective catalytic reduction denitration.

[0039] Example 2

[0040] A preparation method of a copper-based SSZ-39 zeolite catalyst includes the following steps:

[0041] At 25°C, first mix 2.95 g of copper acetate, 0.32 g of niobium chloride, 2.37 g of triethylenetetramine and 147.5 g of deionized water to obtain mixture one. Subsequently, mix 3.6 g of Y zeolite, 23.5 g of N,N-dimethyl-3,5-dimethylpiperidinium hydroxide and 36 g of tetraethyl orthosilicate to obtain mixture two. Finally, mix mixture one and mixture two and age in a reaction kettle at 30°C for 2 h to obtain an initial gel. Use microwave-assisted heating to raise the temperature to 170°C for hydrothermal crystallization for 6 h. The microwave hydrothermal synthesis power is 500 W in the first 3 h and 350 W in the last 3 h; after cooling to room temperature, filter, wash, and dry the filter cake at 80°C for 8 h to obtain a crude product.

[0042] Weigh 0.98 g of manganese acetate tetrahydrate and completely dissolve it in 80 mL of 1 mol / L ammonium chloride solution. Then add 2 g of the crude product prepared in step 1 to the reaction kettle, stir well, and perform ion exchange at 70°C for 8 h. After completion and cooling to room temperature, filter and separate, wash the filter cake with deionized water until neutral, dry at 80°C for 10 h, and calcine at 550°C for 10 h to obtain the copper-based SSZ-39 zeolite catalyst. The XRD pattern of the prepared copper-based SSZ-39 zeolite catalyst is given in Figure 2 it.

[0043] Press and screen the low-temperature denitration AEI catalyst of this example to 20 - 40 mesh. The contents of the components of the SCR activity test gas are as follows: 500 ppm of NH3, 500 ppm of NO, 5 vol% of O2 and N2 balance gas. The SCR activity test of the catalyst is carried out under the conditions of a temperature range of 80 - 500°C, 1 standard atmosphere, and a gas volume space velocity of 60000 h -1 -1, and the obtained SCR activity curve of the AEI zeolite catalyst is inFigure 3 is given in

[0044] After the SCR activity test, the AEI catalyst of this example has very excellent low-temperature denitration activity, and the lowest ignition temperature T 50 is 80 °C, and the NO conversion rate reaches 90% in the wide temperature range of 129-500 °C. Furthermore, the NO conversion rate reaches 95% in the wide temperature range of 137-402 °C.

[0045] The copper-based SSZ-39 zeolite catalyst obtained in this example includes a carrier, the carrier is SSZ-39 zeolite, the active component is copper, and the promoter components are niobium and manganese; the catalyst is a cuboid with a grain side length of 0.4-0.6 μm and a height of 0.1-0.2 μm; based on the total mass of the catalyst, the mass fraction of the active component copper is 2.72 wt%, the mass fraction of the promoter component niobium is 0.31 wt%, and the mass fraction of the promoter component manganese is 1.21 wt%.

[0046] Application of the copper-based SSZ-39 zeolite catalyst of this example in selective catalytic reduction denitration.

[0047] Example 3

[0048] A preparation method of a copper-based SSZ-39 zeolite catalyst, comprising the following steps:

[0049] At 25 °C, first mix 2.08 g of copper nitrate, 0.36 g of ammonium niobium oxalate, 1.26 g of diethylenetriamine and 41.6 g of deionized water to obtain mixture one. Subsequently, mix 3.6 g of SSZ-39 zeolite, 23.5 g of N,N-diethyl-cis-2,6-dimethylpiperidine hydroxide and 36 g of sodium silicate to obtain mixture two. Finally, mix mixture one and mixture two and age in a reaction kettle at 30 °C for 1 h to obtain an initial gel. Use microwave-assisted heating to raise the temperature to 150 °C for hydrothermal crystallization for 6 h. The microwave hydrothermal synthesis power is 450 W in the first 3 h and 300 W in the last 3 h; after cooling to room temperature, filter, wash, and dry the filter cake at 100 °C for 12 h to obtain a crude product.

[0050] Weigh 0.72 g of manganese nitrate and completely dissolve it in 80 mL of 1 mol / L ammonium nitrate solution. Then add 2 g of the crude product prepared in step 1 to the reaction kettle, stir well, and perform ion exchange at 90 °C for 5 h. After completion, filter and separate after cooling to room temperature. Wash the filter cake with deionized water until neutral, dry it at 50 °C for 8 h, and calcine it at 400 °C for 6 h to obtain the copper-based SSZ-39 zeolite catalyst.

[0051] The low-temperature denitration AEI catalyst of this example was tableted and sieved to 20-40 mesh, and the contents of the components of the SCR activity test gas were as follows: 500 ppm of NH3, 500 ppm of NO, 5 vol% of O2 and N2 balance gas. The SCR activity test of the catalyst was carried out at a temperature range of 80-500 °C, 1 standard atmosphere, and a gas hourly space velocity of 60,000 h -1 under the conditions, and the SCR activity curve of the AEI molecular sieve catalyst obtained was given in Figure 3 .

[0052] After the SCR activity test, the AEI catalyst of this example has very excellent low-temperature denitration activity. The lowest ignition temperature T 50 is 87 °C, and the NO conversion rate reaches 90% in a wide temperature range of 128-500 °C. Furthermore, the NO conversion rate reaches 96% in a wide temperature range of 142-500 °C.

[0053] The copper-based SSZ-39 molecular sieve catalyst obtained in this example includes a carrier, the carrier is SSZ-39 molecular sieve, the active component is copper, and the promoter components are niobium and manganese; the catalyst is a cuboid with a grain side length of 0.4-0.6 μm and a height of 0.1-0.2 μm; based on the total mass of the catalyst, the mass fraction of the active component copper is 2.42 wt%, the mass fraction of the promoter component niobium is 0.29 wt%, and the mass fraction of the promoter component manganese is 1.31 wt%.

[0054] Application of the copper-based SSZ-39 molecular sieve catalyst in selective catalytic reduction denitration.

[0055] Example 4

[0056] A preparation method of a copper-based SSZ-39 molecular sieve catalyst includes the following steps:

[0057] At 25 °C, first mix 1.76 g of copper sulfate, 0.36 g of ammonium niobium oxalate, 2.30 g of tetraethylenepentamine and 35.2 g of deionized water to obtain mixture one. Subsequently, mix 3.6 g of Beta molecular sieve, 23.5 g of N,N-diethyl-cis-2,6-dimethylpiperidine hydroxide and 36 g of silica sol to obtain mixture two. Finally, mix mixture one and mixture two and age in a reaction kettle at 30 °C for 3 h to obtain an initial gel. Use microwave-assisted heating to raise the temperature to 200 °C for hydrothermal crystallization for 6 h. The microwave hydrothermal synthesis power is 600 W in the first 3 h and 400 W in the last 3 h; after cooling to room temperature, filter and wash, and dry the filter cake at 90 °C for 11 h to obtain a crude product.

[0058] Weigh 0.50 g of manganese chloride and completely dissolve it in 80 mL of 1 mol / L ammonium nitrate solution. Then add 2 g of the crude product prepared in Step 1 to the reaction kettle, stir well, conduct ion exchange at 80 °C for 10 h. After completion and waiting for it to cool to room temperature, filter and separate. Wash the filter cake with deionized water until it is neutral, dry it at 60 °C for 9 h, and calcine it at 600 °C for 12 h to obtain a copper-based SSZ-39 molecular sieve catalyst.

[0059] Press and screen the low-temperature denitration AEI catalyst of this example to 20 - 40 mesh. The contents of each component of the SCR activity test gas are as follows: 500 ppm of NH3, 500 ppm of NO, 5 vol% of O2, and N2 as the balance gas. The SCR activity test of the catalyst is carried out under the conditions of a temperature range of 80 - 500 °C, 1 standard atmosphere, and a gas volume space velocity of 60000 h -1 under the condition, and the SCR activity curve of the obtained AEI molecular sieve catalyst is given in Figure 3 it.

[0060] Through the SCR activity test, the AEI catalyst of this example has very excellent low-temperature denitration activity. The lowest ignition temperature T 50 is 90 °C, and the NO conversion rate reaches 90% in the wide temperature range of 128 - 500 °C. Furthermore, the NO conversion rate reaches 96% in the wide temperature range of 138 - 500 °C.

[0061] The copper-based SSZ-39 molecular sieve catalyst obtained in this example includes a carrier, the carrier is SSZ-39 molecular sieve, the active component is copper, and the promoter components are niobium and manganese; the catalyst is a cuboid with a grain side length of 0.4 - 0.6 μm and a height of 0.1 - 0.2 μm; based on the total mass of the catalyst, the mass fraction of the active component copper is 2.45 wt%, the mass fraction of the promoter component niobium is 0.27 wt%, and the mass fraction of the promoter component manganese is 1.33 wt%.

[0062] Application of the copper-based SSZ-39 molecular sieve catalyst of this example in selective catalytic reduction denitration.

[0063] Comparative Example 1 (the difference between this comparative example and Example 1 is only that: it does not contain manganese)

[0064] A preparation method of a copper-based SSZ-39 molecular sieve catalyst includes the following steps:

[0065] At 25 °C, first, 2.21 g of copper acetate, 0.32 g of niobium chloride, 1.78 g of triethylenetetramine, and 442 g of deionized water were mixed to obtain Mixture 1. Subsequently, 3.6 g of Y zeolite, 23.5 g of N,N-dimethyl-3,5-dimethylpiperidinium hydroxide, and 36 g of tetraethyl orthosilicate were mixed to obtain Mixture 2. Finally, Mixture 1 and Mixture 2 were mixed and aged in a reaction kettle at 30 °C for 2 h to obtain an initial gel. Microwave-assisted heating was used to raise the temperature to 170 °C for hydrothermal crystallization for 6 h. The microwave hydrothermal synthesis power was 500 W in the first 3 h and 350 W in the last 3 h. After cooling to room temperature, filtration and washing were carried out, and the filter cake was dried at 80 °C for 8 h to obtain a crude product.

[0066] 2 g of the crude product prepared in Step 1 and 80 mL of 1 mol / L ammonium chloride solution were fully stirred in a reaction kettle and then subjected to ion exchange at 70 °C for 8 h. After completion and cooling to room temperature, filtration and separation were carried out. The filter cake was washed with deionized water until neutral, dried at 80 °C for 10 h, and calcined at 550 °C for 10 h to obtain a copper-based SSZ-39 zeolite catalyst. The XRD pattern of the prepared copper-based SSZ-39 zeolite catalyst is shown in Figure 4 the following.

[0067] The copper-based SSZ-39 zeolite catalyst of this comparative example was pressed and sieved to 20 - 40 mesh, and the contents of the components of the SCR activity test gas were as follows: 500 ppm of NH3, 500 ppm of NO, 5 vol% of O2, and N2 balance gas. The SCR activity test of the catalyst was carried out under the conditions of a temperature range of 80 - 500 °C, 1 standard atmosphere, and a gas hourly space velocity of 60000 h -1 The SCR activity curve of the obtained AEI zeolite catalyst is shown in Figure 3 the following.

[0068] After the SCR activity test, the lowest light-off temperature T 50 of the AEI catalyst in this comparative example was 105 °C, and the NO conversion rate reached 90% in the temperature range of 147 - 392 °C.

[0069] Comparative Example 2 (The difference between this comparative example and Example 1 is only that: it does not contain manganese and no ion exchange is carried out)

[0070] A preparation method of a copper-based SSZ-39 zeolite catalyst includes the following steps:

[0071] At 25 °C, first, 2.21 g of copper acetate, 0.32 g of niobium chloride, 1.78 g of triethylenetetramine, and 442 g of deionized water were mixed to obtain Mixture 1. Subsequently, 3.6 g of Y zeolite, 23.5 g of N,N-dimethyl-3,5-dimethylpiperidinium hydroxide, and 36 g of tetraethyl orthosilicate were mixed to obtain Mixture 2. Finally, Mixture 1 and Mixture 2 were mixed and aged in a reaction kettle at 30 °C for 2 h to obtain an initial gel, and hydrothermal crystallization was carried out at 170 °C for 6 h using microwave assistance. The microwave hydrothermal synthesis power was 500 W in the first 3 h and 350 W in the last 3 h; after cooling to room temperature, filtration and washing were carried out, and the filter cake was dried at 80 °C for 8 h and calcined at 550 °C to obtain Cu-SSZ-39 zeolite. The XRD pattern of the prepared zeolite catalyst is shown in Figure 4 is given below.

[0072] The zeolite catalyst of this comparative example was pressed and sieved to 20 - 40 mesh, and the contents of the components of the SCR activity test gas were as follows: 500 ppm of NH3, 500 ppm of NO, 5 vol% of O2, and N2 as the balance gas. The SCR activity test of the catalyst was carried out at a temperature range of 80 - 500 °C, 1 standard atmosphere, and a gas hourly space velocity of 60000 h -1 under the condition, and the obtained SCR activity curve is shown in Figure 3 is given below.

[0073] After the SCR activity test, the lowest light-off temperature T 50 of the AEI catalyst in this comparative example was 116 °C, and the NO conversion reached 90% in a wide temperature range of 149 - 380 °C.

[0074] Comparative Example 3 (The difference between this comparative example and Example 1 is only that oven heating was used instead of microwave-assisted heating)

[0075] A preparation method of a copper-based SSZ-39 zeolite catalyst, comprising the following steps:

[0076] At 25 °C, first, 2.21 g of copper acetate, 0.32 g of niobium chloride, 1.78 g of triethylenetetramine, and 442 g of deionized water were mixed to obtain Mixture 1. Subsequently, 3.6 g of Y zeolite, 23.5 g of N,N-dimethyl-3,5-dimethylpiperidinium hydroxide, and 36 g of tetraethyl orthosilicate were mixed to obtain Mixture 2. Finally, Mixture 1 and Mixture 2 were mixed and aged in a reaction kettle at 30 °C for 2 h to obtain an initial gel, and hydrothermal crystallization was carried out at 170 °C for 48 h in an oven; after cooling to room temperature, filtration and washing were carried out, and the filter cake was dried at 80 °C for 8 h to obtain a crude product.

[0077] Weigh 0.98 g of manganese acetate tetrahydrate and completely dissolve it in 80 mL of 1 mol / L ammonium chloride solution. Then add 2 g of the crude product prepared in Step 1 to the reaction kettle, stir well, and perform ion exchange at 70 °C for 8 h. After completion and waiting for it to cool to room temperature, filter and separate. Wash the filter cake with deionized water until neutral, dry it at 80 °C for 10 h, and calcine it at 550 °C for 10 h to obtain a copper-based SSZ-39 zeolite catalyst. The XRD pattern of the prepared copper-based SSZ-39 zeolite catalyst is shown in Figure 4 as follows.

[0078] For the AEI catalyst of this comparative example, it was pressed and sieved to 20 - 40 mesh, and the contents of each component of the SCR activity test gas were as follows: 500 ppm of NH3, 500 ppm of NO, 5 vol% of O2, and N2 as the balance gas. The SCR activity test of the catalyst was carried out under the conditions of a temperature range of 80 - 500 °C, 1 standard atmosphere, and a gas hourly space velocity of 60000 h -1 to obtain the SCR activity curve of the AEI zeolite catalyst as shown in Figure 3 as follows.

[0079] After the SCR activity test, the lowest light-off temperature T 50 of the AEI catalyst in this comparative example was 98 °C, and the NO conversion rate reached 90% in the wide temperature range of 147 - 448 °C.

[0080] Comparative Example 4 (The difference between this comparative example and Example 1 is only that: the microwave-assisted heating is at a constant power)

[0081] A preparation method of a copper-based SSZ-39 zeolite catalyst, comprising the following steps:

[0082] At 25 °C, first mix 2.21 g of copper acetate, 0.32 g of niobium chloride, 1.78 g of triethylenetetramine, and 442 g of deionized water to obtain Mixture 1. Subsequently, mix 3.6 g of Y zeolite, 23.5 g of N,N-dimethyl-3,5-dimethylpiperidinium hydroxide, and 36 g of tetraethyl orthosilicate to obtain Mixture 2. Finally, mix Mixture 1 and Mixture 2 and age them in the reaction kettle at 30 °C for 2 h to obtain an initial gel, and directly heat it to 170 °C by microwave-assisted heating method for hydrothermal crystallization for 6 h; after cooling to room temperature, filter and wash, and dry the filter cake at 80 °C for 8 h to obtain a crude product.

[0083] Weigh 0.98 g of manganese acetate tetrahydrate and completely dissolve it in 80 mL of 1 mol / L ammonium chloride solution. Then add 2 g of the crude product prepared in Step 1 to the reaction kettle, stir well, and conduct ion exchange at 70 °C for 8 h. After completion and waiting for it to cool to room temperature, filter and separate. Wash the filter cake with deionized water until neutral, dry it at 80 °C for 10 h, and calcine it at 550 °C for 10 h to obtain the copper-based SSZ-39 molecular sieve catalyst. The XRD pattern of the prepared copper-based SSZ-39 molecular sieve catalyst is shown in Figure 4 as follows.

[0084] Press and screen the AEI catalyst of this comparative example to 20 - 40 mesh. The contents of each component of the SCR activity test gas are as follows: 500 ppm of NH3, 500 ppm of NO, 5 vol% of O2, and N2 as the balance gas. The SCR activity test of the catalyst is carried out under the conditions of a temperature range of 80 - 500 °C, 1 standard atmosphere, and a gas volume space velocity of 60000 h -1 The SCR activity curve of the AEI molecular sieve catalyst obtained is shown in Figure 3 as follows.

[0085] After the SCR activity test, the lowest ignition temperature T 50 of the AEI catalyst in this comparative example is 91 °C, and the NO conversion rate reaches 90% in a wide temperature range of 137 - 454 °C.

[0086] The specific surface areas and pore sizes of the catalysts obtained in Examples 1 - 4 and Comparative Examples 1 - 4 are shown in Table 1 below.

[0087] Table 1 Specific surface areas and pore sizes of the catalysts

[0088]

[0089] It should be understood that, in order to streamline this disclosure and assist in understanding one or more of the various inventive aspects, in the above description of the exemplary embodiments of the present invention, the various features of the present invention are sometimes grouped together into a single embodiment, figure, or description thereof. However, the disclosed method should not be construed as reflecting the intention that the claimed invention requires more features than are expressly recited in each claim. Rather, as reflected in the claims, the inventive aspects lie in less than all the features of the previously disclosed embodiments. Thus, the claims following the detailed description are hereby expressly incorporated into the detailed description, where each claim itself serves as a separate embodiment of the present invention.

[0090] Although the present invention has been described based on a limited number of embodiments, those skilled in the art in this technical field will understand that other embodiments can be envisioned within the scope of the present invention thus described. In addition, it should be noted that the language used in this specification is mainly selected for the purpose of readability and teaching, rather than for the purpose of explaining or limiting the subject matter of the present invention. Therefore, many modifications and variations will be obvious to those of ordinary skill in this technical field without departing from the scope and spirit of the appended claims. For the scope of the present invention, the disclosure of the present invention is illustrative rather than restrictive, and the scope of the present invention is defined by the appended claims.

[0091] The above are only the preferred embodiments of the present invention. It should be pointed out that for those of ordinary skill in the art in this technical field, without departing from the principle of the present invention, several improvements and refinements can still be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A copper-based SSZ-39 molecular sieve catalyst, characterized in that, It includes a carrier, the carrier is SSZ-39 molecular sieve, the active component is copper, and the promoter components are niobium and manganese; the catalyst is a cuboid with a grain side length of 0.4 - 0.6 μm and a height of 0.1 - 0.2 μm; based on the total mass of the catalyst, the mass fraction of the active component copper is 2.42 - 2.72 wt%, the mass fraction of the promoter component niobium is 0.27 - 0.37 wt%, and the mass fraction of the promoter component manganese is 1.21 - 1.33 wt%. It includes the following preparation steps: Step 1, at 25 °C, first mix a copper source, a niobium source, an amine compound, and deionized water to obtain mixture one, then mix a molecular sieve seed, a template agent, and a silicon source to obtain mixture two, and finally mix mixture one and mixture two and age in a reaction kettle at 30 °C for 1 - 3 h to obtain an initial gel; Subsequently, use microwave-assisted heating to raise the temperature of the reaction kettle to 150 - 200 °C for hydrothermal crystallization for 6 h; after cooling to room temperature, filter, wash, and dry the filter cake at 80 - 100 °C for 8 - 12 h to obtain a crude product; within the first 3 h of hydrothermal crystallization, the microwave hydrothermal synthesis power is 450 - 600 W; within the last 3 h of hydrothermal crystallization, the microwave hydrothermal synthesis power is 300 - 400 W; Step 2, stir the crude product obtained in Step 1, a manganese source, an ammonium source, and deionized water in a reaction kettle, and perform ion exchange at 70 - 90 °C for 5 - 10 h; after cooling to room temperature, filter, wash, dry the filter cake at 50 - 80 °C for 8 - 10 h, and then calcine at a temperature of 400 - 600 °C for 6 - 12 h to obtain a copper-based SSZ-39 molecular sieve catalyst.

2. The copper-based SSZ-39 molecular sieve catalyst according to claim 1, characterized in that, The mass ratio of mixture one to mixture two is 1:(0.41 - 1.59).

3. The copper-based SSZ-39 molecular sieve catalyst according to claim 1, characterized in that, In Step 1, the mass ratio of the copper source, the niobium source, the amine compound, and deionized water is 1:(0.11 - 0.20):(0.60 - 1.31):(20 - 50).

4. The copper-based SSZ-39 molecular sieve catalyst according to claim 1, characterized in that, The copper source is one of copper sulfate, copper nitrate, and copper acetate; the niobium source is one of niobium chloride or ammonium oxalate niobate; the amine compound is one or a combination of diethylenetriamine, triethylenetetramine, and tetraethylenepentamine.

5. The copper-based SSZ-39 molecular sieve catalyst according to claim 1, characterized in that, In Step 1, the mass ratio of the molecular sieve seed, the template agent, and the silicon source is 1:6.53:

10.

6. The copper-based SSZ-39 molecular sieve catalyst according to claim 1, characterized in that, The molecular sieve seed is a zeolite seed, and the zeolite seed is one of SSZ-39 molecular sieve, Y molecular sieve, and Beta molecular sieve; the template agent is one of N,N-dimethyl-3,5-dimethylpiperidinium hydroxide or N,N-diethyl-cis-2,6-dimethylpiperidinium hydroxide; the silicon source is one of tetraethyl orthosilicate, silica sol, and sodium silicate.

7. The copper-based SSZ-39 molecular sieve catalyst according to claim 1, characterized in that, In Step 2, the mass ratio of the crude product, the manganese source, the ammonium source, and deionized water is 1:(0.25 - 0.49):(2.14 - 3.2):

40.

8. The copper-based SSZ-39 molecular sieve catalyst according to claim 1, characterized in that, The manganese source is one of manganese nitrate, manganese chloride, and manganese acetate tetrahydrate; the ammonium source is one of ammonium nitrate and ammonium chloride.

9. Application of the copper-based SSZ-39 molecular sieve catalyst according to claim 1 in selective catalytic reduction denitration.

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