WO2021082140A1 - Cu-cha copper-containing molecular sieve, and catalyst and use thereof - Google Patents

Abstract

Disclosed are a Cu-CHA copper-containing molecular sieve, and a catalyst thereof and the use thereof in the treatment of diesel vehicle exhaust gas, belonging to the field of catalytic materials. The Cu-CHA copper-containing molecular sieve is composed of a zeolite with a CHA skeleton structure containing silicon, aluminum elements and 1.65-3.05 wt% of Cu, the Cu-CHA molecular sieve also comprises 0.5-1.5 wt% of boron, and the Cu-CHA molecular sieve has an acidity amount of 0.25-0.98 mmol/g. The Cu-CHA molecular sieve has an acid density as high as 0.25-0.98 mmol/g and a Cu content as low as 1.65-3.05 wt%. When used as a catalyst for the selective catalytic reduction of ammonia, same has an excellent NH₃ storage capacity, a good low-temperature activity, and no generation of a CuOx species in a high-temperature section, thus preventing a reduction in high-temperature activity caused by non-selective oxidation of NH₃. The Cu-CHA molecular sieve catalysts exhibit an excellent catalytic activity in a wider temperature window, have both a low temperature and high temperature activity, still exhibit a good catalytic activity after being subjected to a hydrothermal aging treatment, and have a significant performance advantage when applied to a diesel vehicle exhaust gas treatment process.

Description

Copper-containing molecular sieve Cu-CHA and its catalyst and application

This application claims the priority of a Chinese patent application filed with the Chinese Patent Office on October 29, 2019, the application number is 201911034501.0, and the invention title is "Cu-CHA and its catalyst and application", the entire content of which is incorporated by reference In this application.

Technical field

This application relates to a copper-containing molecular sieve Cu-CHA and a preparation method thereof, a catalyst containing copper-containing molecular sieve Cu-CHA, and the application of the catalyst in the exhaust gas treatment of motor vehicles, especially the application in the exhaust gas treatment of diesel vehicles. Material field.

Background technique

Diesel vehicle exhaust includes four major pollutants: carbon monoxide (CO), hydrocarbons (HC), particulate matter (PM) and nitrogen oxides (NOx). Among them, NOx may cause haze, photochemical smog and ozone layer destruction. In 2017, the number of vehicles in my country reached 208 million, and diesel vehicles accounted for only 9.4% of them. However, the NOx emitted by diesel vehicles is about 70% of the total NOx emitted by automobiles. Ammonia Selective Catalytic Reduction (NH ₃ -SCR) is currently recognized as a mainstream diesel vehicle exhaust NOx treatment technology.

The catalyst is _{the core of the NH 3} -SCR technology. Drawing on the successful experience in the field of stationary source denitration, the vanadium-based catalyst has become the first-generation diesel vehicle exhaust denitrification catalyst. Vanadium-based catalysts have many advantages such as high NO conversion rate, excellent sulfur resistance, and low cost. However, due to their narrow temperature window, poor high-temperature performance, and the biological toxicity of the active component vanadium, they have been unable to meet the National Phase VI emission standards. Claim. _{Transition metal-supported molecular sieve-based catalysts are considered to be ideal catalysts for diesel vehicle exhaust NH 3} -SCR technology in the National Phase VI due to their high activity, excellent thermal and hydrothermal stability, and no toxic components.

Zeolites are crystalline or quasi-crystalline aluminosilicates composed of repeated TO ₄ tetrahedral units (or combinations of tetrahedral units), where T is most commonly Si and Al. These units are connected together to form a molecular-sized framework with regular cavities and/or channels in the crystal. Many types of synthetic zeolites have been synthesized, and each has a unique framework based on a unique arrangement of tetrahedral units. In terms of rules, each topology type is assigned a unique three-letter code (such as "CHA") by the International Zeolite Association (IZA).

The Cu-exchanged CHA-type silico-alumina molecular sieve-based catalyst has been commercialized in the _{NH 3 -SCR process of diesel vehicle exhaust due to its good low-temperature activity and hydrothermal stability.} Generally, the exhaust gas temperature of a diesel vehicle under normal operating conditions is about 200-450°C, and the exhaust gas temperature in the cold start phase is lower than 200°C. When the front-end particulate filter (DPF) is regenerated, the instantaneous temperature of the exhaust gas entering the SCR module can reach 700°C. Therefore, it is one of the important performance indicators of the SCR catalyst to show a good NOx conversion rate in a wide range of temperature windows.

Aiming at the problem of improving low-temperature activity, the prior art strategy is to increase the Cu loading of CHA molecular sieve, but this approach often leads to a decrease in high-temperature activity of the catalyst. This is because some Cu species will be converted into CuOx under high temperature conditions under high loading conditions. These CuOx do not have catalytic activity for the conversion of NOx, but can catalyze _{the non-selective oxidation of NH 3} , thereby reducing the high temperature activity of the catalyst. . In addition, under high loading conditions, the Cu-CHA molecular sieve catalyst will irreversibly deactivate its catalytic activity due to the transformation of Cu species during use.

Summary of the invention

In order to solve the above problems, a copper-containing molecular sieve Cu-CHA and its catalyst and its application in diesel vehicle exhaust treatment are provided. The Cu-CHA molecular sieve of the present application has an acid density as high as 0.25-0.98mmol/g and a Cu content as low as 1.65-3.05wt%. As a catalyst for the selective catalytic reduction of ammonia (abbreviated as SCR), it has excellent NH ₃ storage capacity and Good low-temperature activity, and at the same time, there is no formation of CuOx species in the high-temperature section, which avoids the decrease in high-temperature activity caused by non-selective oxidation of _{NH 3.} The Cu-CHA molecular sieve catalyst exhibits excellent catalytic activity in a wide temperature window, taking into account low and high temperature activities, and still exhibits good catalytic activity after hydrothermal aging treatment. It is applied to the exhaust gas treatment process of diesel vehicles. Has significant performance advantages.

According to one aspect of the present application, there is provided a copper-containing molecular sieve Cu-CHA, which contains silicon element, aluminum element, and 1.65-3.05 wt% of Cu aluminosilicate zeolite including CHA framework structure, the Cu-CHA The molecular sieve also includes 0.5-1.5 wt% of boron, and the Cu-CHA molecular sieve has an acid content of 0.25-0.98 mmol/g. Further, the lower limit of the range of the acid amount of the Cu-CHA molecular sieve is selected from 0.3mmol/g, 0.35mmol/g, 0.4mmol/g, 0.45mmol/g, 0.5mmol/g, 0.55mmol/g, 0.6mmol /g, 0.65mmol/g, 0.7mmol/g, 0.75mmol/g, 0.8mmol/g, 0.85mmol/g, 0.9mmol/g or 0.95mmol/g, the upper limit is selected from 0.3mmol/g, 0.35mmol/g , 0.4mmol/g, 0.45mmol/g, 0.5mmol/g, 0.55mmol/g, 0.6mmol/g, 0.65mmol/g, 0.7mmol/g, 0.75mmol/g, 0.8mmol/g, 0.85mmol/g , 0.9mmol/g or 0.95mmol/g. Preferably, it contains 1.95-3.05wt% Cu of zeolite including CHA framework structure.

Optionally, the Cu content in the Cu-CHA molecular sieve is 1.95-3.02 wt%, and the acid content of the Cu-CHA molecular sieve is 0.65-0.96 mmol/g.

Optionally, the lower limit of the boron content range is selected from 0.7 wt%, 0.9 wt%, 1.1 wt%, or 1.3 wt%, and the upper limit is selected from 0.7 wt%, 0.9 wt%, 1.1 wt%, or 1.3 wt%.

Optionally, the boron atom is located on the framework of the zeolite.

Optionally, the molar ratio of silica to alumina in the Cu-CHA molecular sieve is 13-28.

Optionally, the molar ratio of silica to alumina in the Cu-CHA molecular sieve is 18-24. Further, the lower limit of the range of the molar ratio of silica to alumina is selected from 19, 20, 21, 22, or 23, and the upper limit is selected from 19, 20, 21, 22, or 23.

Optionally, the Cu-CHA molecular sieve further contains a metal that is not ion-exchanged with copper, and the content of the non-ion-exchanged metal is less than 1000 ppm; the non-ion-exchanged metal is selected from at least one of alkali metals. Further, the content of the non-ion-exchanged metal is less than 500 ppm. Furthermore, the content of the non-ion-exchanged metal is less than 100 ppm.

Preferably, the non-ion-exchanged metal is sodium or potassium. More preferably, the non-ion-exchanged metal is sodium.

Optionally, the crystal grain size of the Cu-CHA molecular sieve is 0.2-3 μm. Further, the crystal grain size of the Cu-CHA molecular sieve is 0.5-2.5 μm. Furthermore, the lower limit of the crystal grain size of the Cu-CHA molecular sieve is selected from 1 μm, 1.5 μm or 2 μm, and the upper limit of the crystal grain size of the Cu-CHA molecular sieve is selected from 1 μm, 1.5 μm or 2 μm.

Optionally, the specific surface area of the Cu-CHA molecular sieve is not less than 500 m ² /g. Further, the specific surface area of the Cu-CHA molecular sieve is greater than 500 m ² /g.

Optionally, the total pore volume of the Cu-CHA molecular sieve is not less than 0.25 cm ³ /g. Further, the total pore volume of the Cu-CHA molecular sieve is higher than 0.25 cm ³ /g.

Optionally, the method for testing the amount of acid is an ammonia temperature program desorption method.

According to another aspect of the present application, there is provided a method for preparing the copper-containing molecular sieve Cu-CHA, which includes the following steps:

1) Provide aluminosilicate zeolite with CHA framework structure as CHA molecular sieve;

2) The CHA molecular sieve is subjected to NH ₄ ⁺ or H ⁺ exchange to prepare a primary exchange CHA molecular sieve;

3) Using a liquid phase ion exchange method to introduce a copper source into the primary exchange CHA molecular sieve, drying and roasting, to obtain the Cu-CHA molecular sieve.

Optionally, the Cu content in the Cu-CHA molecular sieve is 1.65-3.05 wt%.

Optionally, the preparation method of the CHA molecular sieve includes:

1) Mix the aluminum source, silicon source, boron source, template, alkali and deionized water to obtain an initial mixture;

2) The initial mixture obtained in step 1) is crystallized at 150-200°C for 12-96 h under autogenous pressure to obtain the CHA molecular sieve;

Wherein, the _{molar ratio of Al 2} O ₃ , SiO ₂ , B ₂ O ₃ , template, OH ^- and H ₂ O in the initial mixture is: 1:18-32:0.8-1.7:1.8-3.8: 2.4-6.5: 200-380;

The template is selected from at least one of N,N,N-trimethyladamantamine hydroxide, benzyltrimethylamine and choline.

Optionally, the preparation method of the initial exchange CHA molecular sieve includes: mixing the CHA molecular sieve in an ammonium solution or an acid solution at 70-95° C. for 0.5-20 h, solid-liquid separation, washing, and drying to obtain the initial exchange CHA molecular sieve.

Further, the initial mixture obtained in step 1) is crystallized at 160-170° C. for 48-60 h under autogenous pressure to obtain the CHA molecular sieve.

Further, the _{molar ratio of Al 2} O ₃ , SiO ₂ , B ₂ O ₃ , template, OH ^- and H ₂ O in the initial mixture is: 1:20-28:1.0-1.4:2.2-3.2 : 2.8-5.6: 280-320.

Further, the templating agent is N,N,N-trimethylamantadine hydroxide.

Optionally, the CHA molecular sieve is SSZ-13 molecular sieve.

Optionally, the copper source is selected from at least one of copper acetate, copper nitrate and copper sulfate.

Optionally, the temperature of the liquid phase ion exchange is 20-90°C. Further, the temperature of the liquid phase ion exchange is 50-80°C.

Optionally, the time of the liquid phase ion exchange is 0.5-24h. Further, the time of the liquid phase ion exchange is 2-7h.

According to another aspect of the present application, a catalyst is provided, which includes Cu-CHA molecular sieve;

The Cu-CHA molecular sieve is selected from at least one of any of the Cu-CHA molecular sieves and Cu-CHA molecular sieves prepared according to any of the methods.

Optionally, the catalyst includes the Cu-CHA molecular sieve deposited on the honeycomb substrate.

Preferably, the honeycomb substrate is selected from a wall-flow substrate or a flow-through substrate.

Optionally, the catalyst further includes a binder, and the binder is a zirconium dioxide-based binder.

According to another aspect of the present application, an application of the catalyst in the selective catalytic reduction of ammonia is provided.

According to another aspect of the present application, there is provided an exhaust gas treatment method, which includes contacting the NOx-containing combustion exhaust gas with any of the catalysts described in the present application.

According to another aspect of the present application, there is provided an exhaust gas treatment device, which includes the catalyst described in any one of the present application, wherein the exhaust gas is transported from a diesel engine to a location downstream of the exhaust device, where a reducing agent is added, and all The exhaust gas stream with the reducing agent is delivered to any of the catalysts described in this application.

In this application, "CHA" refers to the CHA topological type identified by the International Zeolite Association (IZA) Structure Committee, and the term "CHA" refers to the topological type chabazite. The term "comprising CHA framework" refers to materials whose main crystalline phase is CHA. Other crystalline states may also exist, but the main crystalline phase contains at least about 90% by weight of CHA, preferably at least about 95% by weight of CHA, and even more preferably at least about 97% by weight or At least about 99 wt% CHA or 100% CHA.

"Calcination" refers to heating a material in air, oxygen, or an inert atmosphere. Calcination is performed to decompose metal salts, promote metal ion exchange within the catalyst, bond the catalyst to the substrate, and remove the template from the micropores of the material prepared here.

"Zolite" refers to an aluminosilicate molecular sieve that includes a framework structured by alumina and silica (ie, repeating SiO ₄ and AlO ₄ tetrahedral units), and also includes doping with other elements in the framework structure. Under certain synthesis conditions, the zeolite can be "silicic", meaning that aluminum is only present as an impurity.

The beneficial effects of this application include but are not limited to:

1. According to the copper-containing molecular sieve Cu-CHA of the present application, due to its higher acid density and lower copper content, it has excellent NH ₃ storage capacity and good low temperature activity. At the same time, there is no CuOx species in the high temperature section. It is generated, avoiding the high-temperature activity reduction caused by the non-selective oxidation of _{NH 3.}

2. The Cu-CHA molecular sieve catalyst according to the present application has more optimized acid properties. Compared with the existing Cu-CHA molecular sieve, the number of weak acid sites has increased, the total acid content has increased, and the formation of CuOx under high temperature conditions It is significantly inhibited, and the thermal and hydrothermal stability of the Cu-CHA molecular sieve is improved.

3. According to the application of Cu-CHA molecular sieve catalyst in diesel vehicle exhaust treatment application, Cu-CHA molecular sieve catalyst exhibits excellent catalytic activity in a wide temperature window, taking into account low temperature and high temperature activity, and it is applied to Diesel vehicle exhaust has significant performance advantages in the process of exhaust gas treatment.

Description of the drawings

The drawings described here are used to provide a further understanding of the application and constitute a part of the application. The exemplary embodiments and descriptions of the application are used to explain the application, and do not constitute an improper limitation of the application. In the attached picture:

Figure 1 is an XRD spectrum of Cu-SSZ-13 molecular sieve 1-3# of Example 1-3 involved in the examples of this application.

Figure 2 is an XRD spectrum of the Cu-SSZ-13 molecular sieve D1-D3# of Comparative Example 1-3 involved in the examples of this application.

Figure 3 is an XRD spectrum of the Cu-MFI molecular sieve catalyst D4# of Comparative Example 4 involved in an embodiment of the application.

Detailed ways

The application is described in detail below in conjunction with the embodiments, but the application is not limited to these embodiments.

Unless otherwise specified, the raw materials in the examples of this application are all purchased through commercial channels.

The analysis method in the embodiment of this application is as follows:

Rigaku Ultima IV powder X-ray diffractometer was used to analyze the crystal form of the obtained sample.

The Rigaku ZSX Primus Ⅱ X-ray fluorescence spectrometer was used to analyze the silicon-to-aluminum ratio and B ₂ O ₃ content of the obtained samples.

The Cu content of the obtained sample was analyzed using the Varian 715-ES plasma emission spectrometer of Agilent Company in the United States.

The conversion rate in the examples of this application is calculated as follows:

Conversion rate of NO = (NO concentration at the reactor inlet-NO concentration at the reactor outlet) / (NO concentration at the reactor inlet) * 100%

In the examples of this application, the NO conversion rate is calculated based on the number of moles of nitrogen.

The examples of this application take Cu-SSZ-13 molecular sieve as an example to illustrate the performance of Cu-CHA molecular sieve, but it is not limited to Cu-SSZ-13 molecular sieve.

According to one embodiment of the present application, Na-SSZ-13 molecular sieve is first prepared by hydrothermal synthesis, and then ammonium exchange is performed to obtain NH ₄ -SSZ-13 molecular sieve, and finally, liquid phase ion exchange of copper is performed to obtain Cu -SSZ-13 molecular sieve.

Example 1 Cu-SSZ-13 molecular sieve 1#

Add 220.0 grams of 25wt% N,N,N-trimethylamantadine hydroxide to 215.0 grams of deionized water, mix well, then add 5.6 grams of sodium hydroxide to it, stir until fully dissolved, and then add 12.4 grams of hydrogen Alumina, mix well, then add 5.8 grams of boric acid to it, and finally add 100.0 grams of solid silica gel to it, and stir well for 2 hours. The above mixture was transferred to a stainless steel reaction vessel lined with polytetrafluoroethylene, placed in a 170°C oven for crystallization for 48 hours, taken out, quenched, and the crystallized product was subjected to solid-liquid separation, washing, drying and roasting to obtain Na-SSZ-13 molecular sieve 1#.

Then it was ammonium exchanged. The Na-SSZ-13 molecular sieve was exchanged at 90°C for 2h with 1mol/L ammonium chloride solution at a solid-to-liquid ratio of 1:10, followed by solid-liquid separation, washing, and drying to obtain Initial exchange of NH ₄ -SSZ-13 molecular sieve 1#.

Weigh 76.8g of Cu(NO ₃ ) ₂ ·H ₂ O and dissolve it in 1000 mL of deionized water to prepare a copper nitrate aqueous solution. Weigh 100g of the NH ₄ -SSZ-13 silicon-alumina molecular sieve obtained in the above steps and add it to the above copper nitrate solution Use nitric acid to adjust the pH value of the above mixture to between 4.5 and 5.0, then place the above mixture at 60°C and stir for 6 hours, suction and dry it, and finally calcinate in an air atmosphere at 550 to 600°C for 4 hours to obtain Cu-SSZ-13 Molecular sieve 1#.

The obtained Cu-SSZ-13 molecular sieve 1# has SiO ₂ /Al ₂ O ₃ = 19.8, copper content of Cu = 2.30 wt%, boron content of B ₂ O ₃ = 0.94 wt%, and acid content of 0.88 mmol/g.

Example 2 Cu-SSZ-13 molecular sieve 2#

Add 161.0 grams of 25wt% N,N,N-trimethylamantadine hydroxide into 269.4 grams of deionized water, mix well, then add 3.6 grams of sodium hydroxide to it, stir until fully dissolved, and then add 25.0 grams of partial Sodium aluminate, mix well, then add 2.4 grams of boric acid to it, and finally add 100.0 grams of solid silica gel to it, and stir well for 2 hours. The above mixture was transferred to a stainless steel reaction kettle lined with polytetrafluoroethylene, placed in a 160°C oven for crystallization for 60 hours, taken out, quenched, and the crystallized product was subjected to solid-liquid separation, washing, drying and roasting to obtain Na-SSZ-13 molecular sieve 2#.

Then it was ammonium exchanged. The Na-SSZ-13 molecular sieve was exchanged at 90°C for 2h with 1mol/L ammonium chloride solution at a solid-to-liquid ratio of 1:10, followed by solid-liquid separation, washing, and drying to obtain Initial exchange of NH ₄ -SSZ-13 molecular sieve 2#.

Weigh 63.5g of Cu(CH ₃ COO) ₂ ·H ₂ O and dissolve 1000mL of deionized water to prepare a copper acetate aqueous solution. Weigh 100g of NH ₄ -SSZ-13 silicon aluminum molecular sieve obtained in the above steps, and add the above copper acetate solution The pH value of the above mixture was adjusted to between 4.5 and 5.0 with nitric acid, and then the above mixture was placed at 80 ℃ and stirred for 3 hours, suction filtered and dried, and finally calcined in an air atmosphere at 550 to 600 ℃ for 4 hours to obtain Cu-SSZ- 13 Molecular Sieve 2#.

The obtained Cu-SSZ-13 molecular sieve 2# has SiO ₂ /Al ₂ O ₃ =14.6, a copper content of Cu=3.02 wt%, a boron content of B ₂ O ₃ =0.82 wt%, and an acid content of 0.96 mmol/g.

Example 3 Cu-SSZ-13 molecular sieve 3#

Add 136.0 grams of 25wt% N,N,N-trimethylamantadine hydroxide solution into 20.0 grams of deionized water, mix well, then add 7.0 grams of sodium hydroxide to it, stir until fully dissolved, and then add 7.2 grams Pseudo-boehmite, mix thoroughly, then add 1.6 grams of boric acid to it, and finally add 320.0 grams of silica sol with a solid content of 30% to it, and fully stir for 2 hours. The above mixture was transferred to a stainless steel reaction kettle lined with polytetrafluoroethylene, placed in a 170°C oven for crystallization for 60 hours, taken out, quenched, and the crystallization product was subjected to solid-liquid separation, washing, drying and roasting to obtain Na-SSZ-13 molecular sieve 3#.

Then it was ammonium exchanged, and the Na-SSZ-13 molecular sieve 3# was exchanged at 90℃ for 2h with 1mol/L ammonium chloride solution at a solid-to-liquid ratio of 1:10, followed by solid-liquid separation, washing, and drying , Get the initial exchange NH ₄ -SSZ-13 molecular sieve 3#.

Weigh 78.9g CuSO ₄ ·5H ₂ O dissolved in 1000mL deionized water to prepare a copper sulfate aqueous solution, weigh 100g NH ₄ -SSZ-13 silica-alumina molecular sieve, add to the copper sulfate solution, use nitric acid to The pH value is adjusted to between 4.5 and 5.0, and then the above mixture is stirred at 80°C for 3 hours, filtered and dried by suction, and finally calcined in an air atmosphere at 550 to 600°C for 4 hours to obtain Cu-SSZ-13 molecular sieve 3#.

The obtained Cu-SSZ-13 molecular sieve 3# has SiO ₂ /Al ₂ O ₃ =27.2, the copper content is Cu=1.95 wt%, the boron content is B ₂ O ₃ =0.53 wt%, and the acid content is 0.65 mmol/g.

Example 4 Characterization of Cu-SSZ-13 molecular sieve 1-3#

The XRD pattern of Cu-SSZ-13 molecular sieve 1# prepared in Example 1 is shown as line 1 in Fig. 1, and the XRD pattern of Cu-SSZ-13 molecular sieve 2# prepared in Example 2 is shown as line 2 in Fig. 1. Implementation The XRD pattern of Cu-SSZ-13 molecular sieve 3# prepared in Example 3 is shown in line 3 in Figure 1. The XRD peak data of Cu-SSZ-13 molecular sieve 1-3# prepared in Example 1-3 are shown in Table 1. Show.

Table 1

It can be seen from Table 1 that the XRD results of Cu-SSZ-13 molecular sieve 1-3# prepared in Example 1-3 are in line with the characteristic peaks of the CHA framework structure, and no characteristic peaks attributed to copper oxides are found; with SiO ₂ /(Al ₂ O ₃ +B ₂ O ₃ ) increases, the 2theta position of the characteristic peak gradually decreases.

Comparative Example 1 Cu-SSZ-13 molecular sieve D1#

_{The initial exchange NH 4} -SSZ-13 molecular sieve D1# was synthesized according to the process described in Example 1, wherein the amount of aluminum hydroxide added was changed from 12.4 g to 20.2 g, and other conditions remained unchanged.

According to the process described in Example 1, the liquid phase ion exchange method was used to _{introduce Cu into the obtained primary exchange NH 4} -SSZ-13 molecular sieve D1#, and the experimental conditions were completely consistent with the conditions described in Example 1.

The obtained Cu-SSZ-13 molecular sieve D1# has SiO ₂ /Al ₂ O ₃ = 10.8, copper content of Cu = 2.18 wt%, boron content of B ₂ O ₃ = 0.89 wt%, and acid content of 1.07 mmol/g.

Comparative example 2 Cu-SSZ-13 molecular sieve D2#

_{The initial exchange NH 4} -SSZ-13 molecular sieve D2# was synthesized according to the process described in Example 1. The addition amount of boric acid was changed from 5.8 g to 0 g, and other conditions remained unchanged.

According to the process described in Example 1, the liquid phase ion exchange method was used to _{introduce Cu into the obtained primary exchange NH 4} -SSZ-13 molecular sieve D2#, and the experimental conditions were completely consistent with the conditions described in Example 1.

The obtained Cu-SSZ-13 molecular sieve D2# has SiO ₂ /Al ₂ O ₃ = 19.4, the copper content is Cu = 2.23 wt%, the boron content is B ₂ O ₃ = 0 wt%, and the acid content is 0.46 mmol/g.

Comparative example 3 Cu-SSZ-13 molecular sieve D3#

_{The initial exchange NH 4} -SSZ-13 molecular sieve 1# was synthesized according to the process described in Example 1, and the experimental conditions were completely consistent with those described in Example 1.

Weigh 127.0g of Cu(CH ₃ COO) ₂ ·H ₂ O and dissolve in 1000 mL of deionized water to prepare a copper acetate aqueous solution. Weigh 100g of NH ₄ -SSZ-13 silica-alumina molecular sieve synthesized in the above steps, and add the above acetic acid In the copper solution, the above mixture was stirred at 60°C for 6 hours, filtered and dried by suction, and finally calcined in an air atmosphere at 550-600°C for 4 hours to obtain Cu-SSZ-13 molecular sieve D3#.

The obtained Cu-SSZ-13 molecular sieve D3# has SiO ₂ /Al ₂ O ₃ = 19.2, the copper content is Cu = 3.24 wt%, the boron content is B ₂ O ₃ = 0.92 wt%, and the acid content is 0.56 mmol/g.

Comparative example 4 Cu-MFI molecular sieve D4#

Add 260.0 grams of 25wt% tetrapropyl ammonium hydroxide into 237.0 grams of deionized water, mix well, then add 13.5 grams of sodium metaaluminate, mix well, then add 5.8 grams of boric acid, and finally add 100.0 grams of solid to it Silica gel, stir well for 2h. The above mixture was transferred to a stainless steel reaction kettle lined with polytetrafluoroethylene, placed in a 170°C oven for crystallization for 72 hours, taken out, quenched, and the crystallization product was subjected to solid-liquid separation, washing, drying and roasting to obtain Na-MFI molecular sieve.

Then it was ammonium exchanged, and the Na-MFI molecular sieve was exchanged at 90℃ for 2h with 1mol/L ammonium chloride solution at a solid-to-liquid ratio of 1:10, followed by solid-liquid separation, washing, and drying to obtain NH ₄ -MFI molecular sieve;

Weigh 63.5g Cu(CH ₃ COO) ₂ ·H ₂ O and dissolve in 1000 mL deionized water to prepare a copper acetate aqueous solution. Weigh 100g of NH ₄ -MFI silica-alumina molecular sieve and add it to the copper acetate solution. The pH value of the mixture is adjusted to between 4.5-5.0, and then the above-mentioned mixture is stirred at 80°C for 3h, filtered and dried by suction, and finally calcined in an air atmosphere at 550-600°C for 4h to obtain Cu-MFI molecular sieve D4#.

The obtained Cu-MFI molecular sieve D4# has SiO ₂ /Al ₂ O ₃ =27.9, copper content of Cu = 2.28 wt%, boron content of B ₂ O ₃ =0.86 wt%, and acid content of 0.49 mmol/g.

Comparative example 5 Characterization of Cu-SSZ-13 molecular sieve D1-D3#

The XRD pattern of Cu-SSZ-13 molecular sieve D1# prepared in Comparative Example 1 is shown in line 1 in Figure 2, and the XRD pattern of Cu-SSZ-13 molecular sieve D2# prepared in Comparative Example 2 is shown in line 2 in Figure 2. The XRD pattern of Cu-SSZ-13 molecular sieve D3# prepared in Example 3 is shown in line 3 in Figure 2, and the XRD peak data of Cu-SSZ-13 molecular sieve D1-3# prepared in Comparative Example 1-3 are shown in Table 2. Show.

Table 2

It can be seen from Table 2 that the XRD results of Cu-SSZ-13 molecular sieve D1-3# prepared in Comparative Example 1-3 are consistent with the characteristic peaks of the CHA framework structure, and no characteristic peaks attributed to copper oxides are found; among them, molecular sieve D1 # SiO ₂ /(Al ₂ O ₃ +B ₂ O ₃ ) is the lowest, correspondingly the 2theta angle value of the characteristic peak is the largest, D2# SiO ₂ /(Al ₂ O ₃ +B ₂ O ₃ ) is the highest, corresponding to the characteristic The 2theta angle value of the peak is the smallest.

Comparative Example 6 Characterization of Cu-MFI Molecular Sieve D4#

The XRD pattern of Cu-SSZ-13 molecular sieve D4# prepared in Comparative Example 4 is shown in Fig. 3, and the XRD peak data of Cu-SSZ-13 molecular sieve D4# is shown in Table 3.

table 3

It can be seen from Table 3 that the XRD results of the Cu-MFI molecular sieve D4# prepared in Comparative Example 4 are consistent with the characteristic peaks of the MFI framework structure, and no characteristic peaks attributed to copper oxides are found.

Example 5 Preparation of Cu-SSZ-13 molecular sieve catalyst 1-3#, Cu-SSZ-13 molecular sieve catalyst D1-D3#, and Cu-MFI molecular sieve catalyst D4#

The prepared Cu-SSZ-13 molecular sieve 1-3#, Cu-SSZ-13 molecular sieve D1-D3#, and Cu-MFI molecular sieve D4# were respectively ground and sieved, and the particle size of 80-100 mesh was taken as the catalyst sample. They are respectively marked as Cu-SSZ-13 molecular sieve catalyst 1-3#, Cu-SSZ-13 molecular sieve catalyst D1-D3#, and Cu-MFI molecular sieve catalyst D4#.

Example 6 The catalytic performance of Cu-SSZ-13 molecular sieve catalyst 1-3#, Cu-SSZ-13 molecular sieve catalyst D1-D3#, and Cu-MFI molecular sieve catalyst D4# were tested

_{The NH 3} -SCR catalytic performance of Cu-SSZ-13 molecular sieve catalyst 1-3#, Cu-SSZ-13 molecular sieve catalyst D1-D3#, and Cu-MFI molecular sieve catalyst D4# were tested, and the test temperature was 100-550℃. At normal pressure, the reaction space velocity is 35000h ^-1 , the _{concentration of NH 3} is 500 ppm, the concentration of NO is 500 ppm, and 5% O ₂ and N _{2 are} used as balance gas. The test results of the conversion rate of NO at different temperatures in _{the NH 3} -SCR reaction of Cu-SSZ-13 molecular sieve catalyst 1-3#, Cu-SSZ-13 molecular sieve catalyst D1-D3#, and Cu-MFI molecular sieve catalyst D4# are shown in the table 4 shown.

Table 4

It can be seen from Table 4 that the Cu-SSZ-13 molecular sieve D1# prepared according to Comparative Example 1 has a silicon-to-aluminum ratio SiO ₂ /Al ₂ O ₃ of 10.8 which is significantly lower than that of the Cu-SSZ-13 molecular sieve 1# prepared according to Example 1. ; Its acid content is 1.07mol/g, which is higher than Cu-SSZ-13 molecular sieve 1#; Cu-SSZ-13 molecular sieve catalyst D1# has a significantly lower NO conversion rate at 200℃ than Cu-SSZ-13 molecular sieve catalyst 1# .

It can be seen from Table 4 that the Cu-SSZ-13 molecular sieve D2# prepared according to Comparative Example 2 does not contain boron; its silicon-to-aluminum ratio SiO ₂ /Al ₂ O _{3 is the} same as that of the Cu-SSZ-13 molecular sieve prepared according to Example 1. # Is equivalent; its acid content is 0.46mol/g, which is significantly lower than Cu-SSZ-13 molecular sieve 1#; Cu-SSZ-13 molecular sieve catalyst D2# at 200 ℃, the NO conversion rate is significantly lower than Cu-SSZ-13 molecular sieve Catalyst 1#.

It can be seen from Table 4 that the Cu-SSZ-13 molecular sieve D3# prepared according to Comparative Example 3 has a silicon-to-aluminum ratio SiO ₂ /Al ₂ O ₃ equivalent to the Cu-SSZ-13 molecular sieve 1# prepared according to Example 1; its boron The content is equivalent to the Cu-SSZ-13 molecular sieve 1# prepared according to Example 1; the Cu content is 3.24wt%, which is significantly higher than the Cu-SSZ-13 molecular sieve 1#; the Cu-SSZ-13 molecular sieve catalyst D2# is at 200°C The conversion rate of NO at 550℃ is significantly lower than that of Cu-SSZ-13 molecular sieve catalyst 1#.

It can be seen from Table 4 that the Cu-MFI molecular sieve D4# prepared according to Comparative Example 4 has a framework structure of MFI that is different from the Cu-SSZ-13 molecular sieve 1# prepared according to Example 1. The Cu-MFI molecular sieve catalyst D4# is at 200°C and The conversion rate of NO at 550℃ is significantly lower than that of Cu-SSZ-13 molecular sieve 1#.

The above are only the embodiments of the present application, and the protection scope of the present application is not limited by these specific embodiments, but is determined by the claims of the present application. For those skilled in the art, this application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the technical ideas and principles of this application shall be included in the protection scope of this application.

Claims (22)

1. A copper-containing molecular sieve Cu-CHA, which is characterized in that it contains silicon element, aluminum element and 1.65-3.05wt% of Cu including CHA framework structure zeolite, and the Cu-CHA molecular sieve also includes 0.5-1.5wt% The amount of the Cu-CHA molecular sieve acid is 0.25-0.98mmol/g.
2. The copper-containing molecular sieve Cu-CHA according to claim 1, wherein the Cu content in the Cu-CHA molecular sieve is 1.95-3.02 wt%, and the acid content of the Cu-CHA molecular sieve is 0.65-0.96 mmol/ g.
3. The copper-containing molecular sieve Cu-CHA according to claim 1, wherein the boron atom is located on the framework of the zeolite.
4. The copper-containing molecular sieve Cu-CHA according to claim 1, wherein the molar ratio of silica to alumina in the Cu-CHA molecular sieve is 13-28.
5. The copper-containing molecular sieve Cu-CHA according to claim 1, wherein the Cu-CHA molecular sieve further contains metals that are not exchanged with copper ions, and the content of the metals that are not ion-exchanged is less than 1000 ppm;

   The metal that is not ion-exchanged is selected from at least one of alkali metals.
6. The Cu-CHA copper-containing molecular sieve according to claim 1, wherein the crystal grain size of the Cu-CHA molecular sieve is 0.2-3 μm.
7. The copper-containing molecular sieve Cu-CHA according to claim 1, wherein the specific surface area of the Cu-CHA molecular sieve is not less than 500 m ² /g.
8. The copper-containing molecular sieve Cu-CHA according to claim 1, wherein the total pore volume of the Cu-CHA molecular sieve is not less than 0.25 cm ³ /g.
9. The copper-containing molecular sieve Cu-CHA according to claim 1, wherein the method for testing the amount of acid is an ammonia temperature programmed desorption method.
10. The method for preparing copper-containing molecular sieve Cu-CHA according to any one of claims 1-9, characterized in that it comprises the following steps:

    1) Provide aluminosilicate zeolite with CHA framework structure as CHA molecular sieve;

    2) The CHA molecular sieve is subjected to NH ₄ ⁺ or H ⁺ exchange to prepare a primary exchange CHA molecular sieve;

    3) Using a liquid phase ion exchange method to introduce a copper source into the primary exchange CHA molecular sieve, drying and roasting, to obtain the Cu-CHA molecular sieve.
11. The preparation method according to claim 10, wherein the content of copper in the Cu-CHA molecular sieve is 1.65-3.05 wt%.
12. The preparation method according to claim 10, wherein the preparation method of the CHA molecular sieve comprises:

    1) Mix the aluminum source, silicon source, boron source, template, alkali and deionized water to obtain an initial mixture;

    2) The initial mixture obtained in step 1) is crystallized at 150-200°C for 12-96 h under autogenous pressure to obtain the CHA molecular sieve;

    Wherein, the _{molar ratio of Al 2} O ₃ , SiO ₂ , B ₂ O ₃ , template, OH ^- and H ₂ O in the initial mixture is: 1:18-32:0.8-1.7:1.8-3.8: 2.4-6.5: 200-380;

    The template is selected from at least one of N,N,N-trimethyladamantamine hydroxide, benzyltrimethylamine and choline.
13. The preparation method according to claim 10, wherein the CHA molecular sieve is SSZ-13 molecular sieve.
14. The preparation method according to claim 10, wherein the copper source is selected from at least one of copper acetate, copper nitrate and copper sulfate.
15. The preparation method according to claim 10, wherein the temperature of the liquid phase ion exchange is 20-90°C.
16. The preparation method according to claim 10, wherein the time of the liquid phase ion exchange is 0.5-24h.
17. A catalyst, characterized in that it comprises Cu-CHA molecular sieve;

    The Cu-CHA molecular sieve is selected from at least one of the Cu-CHA molecular sieve according to any one of claims 1-9 and the Cu-CHA molecular sieve prepared by the method according to any one of claims 10-16 Kind.
18. The catalyst according to claim 17, characterized in that it comprises the Cu-CHA molecular sieve deposited on the honeycomb substrate, and the honeycomb substrate is selected from a wall-flow substrate or a flow-through substrate .
19. The catalyst according to claim 17, characterized in that it further comprises a binder, and the binder is a zirconium dioxide-based binder.
20. The use of the catalyst of any one of claims 17-19 in the selective catalytic reduction of ammonia.
21. An exhaust gas treatment method, comprising contacting NOx-containing combustion exhaust gas with the catalyst according to any one of claims 17-19.
22. An exhaust gas treatment device, characterized in that it comprises the catalyst according to any one of claims 17-19, wherein the exhaust gas is transported from the diesel engine to a position downstream of the exhaust gas device, where a reducing agent is added, and the added The exhaust gas stream of reducing agent is delivered to the catalyst of claims 17-19.

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