A nano SSZ-13 molecular sieve, its preparation method and application
The synthesis of nano-SSZ-13 molecular sieves via a one-step crystallization method solves the problems of high diffusion resistance and high cost of large-grain SSZ-13 molecular sieves, achieving high-efficiency catalytic performance and low-cost catalyst application.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- CHINA PETROLEUM & CHEMICAL CORP
- Filing Date
- 2022-10-10
- Publication Date
- 2026-06-30
AI Technical Summary
The existing SSZ-13 molecular sieve has large crystal grains, which leads to high diffusion resistance of reactants and products in catalytic reactions, easy carbon deposition, and affects catalyst life. In addition, the cost of organic structure directing agents is high.
Nano-SSZ-13 molecular sieves were synthesized using a one-step crystallization method, with the SiO2/Al2O3 molar ratio controlled at 7.6–28.0. A special aluminum source and a dual-organic structure directing agent were used to prepare nano-SSZ-13 molecular sieves with a particle size of 30–80 nm, avoiding the addition of seed crystals.
The catalytic performance of the catalyst was improved, with a NOx conversion rate of over 85%, and production costs were reduced.
Smart Images
Figure CN117902593B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of molecular sieve technology, specifically relating to a nano SSZ-13 molecular sieve, its preparation method, and its application. Background Technology
[0002] In industry, molecular sieve materials are widely used in catalysis, ion exchange, adsorption, and separation due to their open structure and large surface area. Subtle differences in the structure of these materials indicate differences in various observable properties used to characterize them, such as their morphology, specific surface area, pore size, and the variability of these dimensions. At the same time, it also means that they themselves have significant differences in catalytic and adsorption properties.
[0003] SSZ-13 is a small-pore molecular sieve with a CHA topology. It consists of AlO4 and SiO4 tetrahedra connected end-to-end by oxygen atoms, arranged in an orderly fashion into an ellipsoidal cage (0.73 nm × 1.2 nm) with an eight-membered ring structure and a three-dimensional intersecting channel structure, with a pore size of 0.38 nm × 0.38 nm. SSZ-13 molecular sieves possess characteristics such as a small pore size (0.38 nm), high specific surface area, good hydrothermal stability, adjustable acid centers, and excellent ion exchange capacity, making them suitable for removing NO from automotive exhaust. x It has shown excellent performance in fields such as (NH3-SCR), methanol conversion (MTH) and CO2 adsorption separation, and has been widely used in many industrial catalytic processes in recent years.
[0004] Patent CN108117089B discloses the synthesis of CHA-structured molecular sieves using alkylammonium hydroxide and adamantylammonium hydroxide as dual-organic structure directing agents, with a Si / Al molar ratio between 4 and 8 and a specific surface area of 400–800 m². 2 / g, with a crystallite size of 0.8–20 μm, exhibiting high separation performance in CO2 / N2 and N2 / O2 mixed gases. Patent CN114057208A discloses a method for synthesizing a CHA-type molecular sieve using a dual-organic structure directing agent and for preparing an SCR catalyst using it. The method employs N,N,N-trialkylcyclohexyl quaternary ammonium salt / base and N,N-dialkylpyrrolidine onium salt / base compounds to synthesize the CHA molecular sieve, with a crystallite size of 1–5 μm.
[0005] SSZ-13 molecular sieve is a microporous molecular sieve, usually prepared by hydrothermal crystallization. The large crystal size of the molecular sieve can cause significant resistance to the diffusion of reactants and products in catalytic reactions, easily leading to carbon deposition and affecting the service life of the catalyst. In addition, it uses a large amount of organic structure directing agent N,N,N-trimethyladamantane ammonium, resulting in high cost. Summary of the Invention
[0006] The technical problem to be solved by the present invention is to provide a new nano SSZ-13 molecular sieve, its preparation method and application. This molecular sieve is used as a catalyst and adsorbent in the field of diesel vehicle exhaust gas treatment (NH3-SCR reaction) and has significant performance advantages.
[0007] The first aspect of the present invention provides a nano SSZ-13 molecular sieve, wherein the crystal particle size of the nano SSZ-13 molecular sieve is 30-80 nm and the SiO2 / Al2O3 molar ratio is 7.6-28.0.
[0008] Furthermore, the crystal particle size of the nano SSZ-13 molecular sieve is 35-75 nm, and the SiO2 / Al2O3 molar ratio is 8.0-24.5, preferably 8.2-24.5.
[0009] Furthermore, the total specific surface area of the nano-SSZ-13 molecular sieve is not less than 550 m². 2 / gram, preferably 550-900 meters 2 / gram; external specific surface area not less than 50 m² 2 / gram, preferably 50-150 meters 2 / gram.
[0010] Furthermore, the total pore volume of the nano-SSZ-13 molecular sieve is not less than 0.30 cm³. 3 / gram, preferably 0.30 to 0.80 cm 3 / gram; micropore volume not less than 0.20 cm³ 3 / gram, preferably 0.20 to 0.30 cm 3 / gram.
[0011] A second aspect of this invention provides a method for preparing nano-SSZ-13 molecular sieves, comprising the following steps:
[0012] A silicon source, an aluminum source, an alkali source, organic structure directing agent a, organic structure directing agent b, and water are mixed and crystallized to obtain the nano SSZ-13 molecular sieve; and optionally, the obtained nano SSZ-13 molecular sieve is calcined.
[0013] Furthermore, the added silicon source is calculated as SiO2, the aluminum source as Al2O3, and the alkali source (as OH) - The mixture consists of SiO2, Al2O3, alkali source, SDA1, SDA2, and H2O, in a molar ratio of 1:0.036–0.130:0.20–0.40:0.08–0.20:0.005–0.035:12–50.
[0014] Furthermore, the added silicon source is calculated as SiO2, the aluminum source as Al2O3, and the alkali source (as OH) - The mixture consists of SiO2, Al2O3, alkali source, SDA1, SDA2, and H2O, in a molar ratio of 1:0.040–0.125:0.22–0.38:0.08–0.20:0.008–0.030:14–40.
[0015] Furthermore, the molar ratio of SDA1 to SDA2 is greater than 2:1 to 40:1, preferably 4:1 to 20:1.
[0016] Furthermore, the silicon source is silica sol; the aluminum source is sodium aluminate.
[0017] Furthermore, the sodium aluminate contains 38% to 43% Al2O3 by weight and 30% to 33% Na2O by weight.
[0018] Furthermore, the alkali source is selected from at least one inorganic alkali with alkali metal or alkaline earth metal as cation; wherein the alkali metal is selected from at least one of K and Na, and the alkaline earth metal is selected from at least one of Mg, Ba, and Ca.
[0019] Furthermore, the organic structure directing agent a (SDA1) is selected from at least one of tetraethylammonium hydroxide and methyltriethylammonium hydroxide.
[0020] Furthermore, the organic structure directing agent b (SDA2) is N,N,N-trimethyladamantane ammonium.
[0021] Furthermore, the crystallization conditions of the reaction mixture are crystallization at 130–180°C for 1.5–7.0 days, preferably at 140–170°C for 2.0–6.0 days.
[0022] Furthermore, the crystallization process of the reaction mixture is a dynamic crystallization by rotation or stirring, with a rotation or stirring speed of 10 to 300 rpm, preferably 10 to 150 rpm.
[0023] Furthermore, no seed crystals need to be added during the crystallization process of the molecular sieve.
[0024] Furthermore, the yield of the molecular sieve product exceeds 80%.
[0025] Furthermore, the crystallization can be carried out in any manner conventionally known in the art, such as by mixing the silicon source, aluminum source, alkali source, organic structure directing agent a, organic structure directing agent b and water in a predetermined ratio, and then heating the resulting mixture under crystallization conditions.
[0026] Furthermore, after the crystallization step, the obtained mixture can be processed to obtain the product by any conventionally known separation method. Examples of such separation methods include filtering, washing, and drying the obtained mixture. Here, the filtration, washing, and drying can be performed in any manner conventionally known in the art. Specifically, for example, the filtration can be performed by simply vacuum filtering the obtained product mixture. For example, washing can be performed using deionized water and / or ethanol. For example, the drying temperature can be 40–250°C, preferably 60–150°C, and the drying time can be 8–30 hours, preferably 10–20 hours. This drying can be carried out under normal pressure or under reduced pressure.
[0027] Furthermore, the nano-SSZ-13 molecular sieve obtained after the crystallization step can be further processed by calcination to obtain Na-SSZ-13 molecular sieve. The calcination can be carried out in any manner conventionally known in the art, for example, the calcination temperature is generally 300–800°C, preferably 400–650°C, and the calcination time is generally 1–10 hours, preferably 3–6 hours. In addition, the calcination is generally carried out in an oxygen-containing atmosphere, such as air or an oxygen atmosphere.
[0028] A third aspect of the present invention provides a nano-SSZ-13 molecular sieve prepared according to any of the preparation methods described in the second aspect above.
[0029] Furthermore, the crystal particle size of the nano-SSZ-13 molecular sieve is 30-80 nm, preferably 35-75 nm, and the SiO2 / Al2O3 molar ratio is 7.6-28.0, preferably 8.0-24.5.
[0030] Furthermore, the total specific surface area of the nano-SSZ-13 molecular sieve is not less than 550 m². 2 / gram, preferably 550-900 meters 2 / gram; external specific surface area not less than 50 m² 2 / gram, preferably 50-150 meters 2 / gram.
[0031] Furthermore, the total pore volume of the nano-SSZ-13 molecular sieve is not less than 0.30 cm³. 3 / gram, preferably 0.30 to 0.80 cm 3 / gram; micropore volume not less than 0.20 cm³ 3 / gram, preferably 0.20 to 0.30 cm 3 / gram.
[0032] The fourth aspect of the present invention also provides a nano SSZ-13 molecular sieve composition comprising a nano SSZ-13 molecular sieve prepared according to any of the preparation methods described in the first aspect or according to any of the preparation methods described in the second aspect, and a binder.
[0033] The fifth aspect of the present invention also provides the use of nano SSZ-13 molecular sieves prepared according to any of the methods described in the first aspect above, or nano SSZ-13 molecular sieves prepared according to any of the methods described in the second aspect above, or nano SSZ-13 molecular sieve compositions described in the fourth aspect above, as catalysts.
[0034] Furthermore, the nano SSZ-13 molecular sieve or the nano SSZ-13 molecular sieve composition is used as a catalyst in diesel vehicle exhaust gas treatment (NH3-SCR reaction).
[0035] Furthermore, in the aforementioned application, the Na-SSZ-13 molecular sieve is first subjected to NH4+ sequentially. + and Cu 2+ After exchange treatment and calcination, Cu-SSZ-13 molecular sieve catalyst is prepared for use.
[0036] Furthermore, the NH4 + After ion exchange at 30–80°C for 1–8 hours, the solid is separated, and the exchange process is repeated 0–2 times to obtain NH4-SSZ-13 molecular sieve. The ammonium salt used for exchange is selected from at least one of ammonium chloride, ammonium nitrate, ammonium carbonate, and ammonium sulfate; the concentration of ammonium ions in the ammonium salt solution is 0.1–1 mol / L, and the solid-liquid mass ratio of Na-SSZ-13 to the ammonium salt solution is 1:5–1:20.
[0037] Furthermore, the Cu 2+ After ion exchange at 40–90℃ for 4–24 h, the solid is separated and the exchange is repeated 0–2 times in the above manner to obtain Cu-SSZ-13 molecular sieve. The copper salt used for exchange is selected from at least one of divalent copper salts, namely copper nitrate, copper acetate, copper chloride, and copper sulfate; the concentration of copper ions in the copper salt solution is 0.01–0.1 mol / L, and the solid-liquid mass ratio of NH4-SSZ-13 to the copper salt solution is 1:5–1:20.
[0038] Furthermore, in Cu 2+After the exchange process is complete, the product can be obtained from the mixture by any conventionally known separation method. Examples of such separation methods include filtering, washing, and drying the obtained mixture. Here, the filtration, washing, and drying can be performed in any manner conventionally known in the art. Specifically, for example, the filtration can be performed by simply vacuum filtering the obtained product mixture. For example, washing can be performed using deionized water and / or ethanol. For example, the drying temperature can be 40–250°C, preferably 60–150°C, and the drying time can be 8–30 hours, preferably 10–20 hours. This drying can be carried out under normal pressure or under reduced pressure.
[0039] Furthermore, the calcination can be carried out in any manner conventionally known in the art, for example, the calcination temperature is generally 300–800°C, preferably 400–650°C, and the calcination time is generally 1–10 hours, preferably 3–6 hours. In addition, the calcination is generally carried out in an oxygen-containing atmosphere, such as air or an oxygen atmosphere.
[0040] Compared with the prior art, the beneficial effects of the present invention are as follows:
[0041] The nano-SSZ-13 molecular sieve of this invention has a crystal particle size of 30–80 nm and a SiO2 / Al2O3 molar ratio of 7.6–28.0. The nano-Cu-SSZ-13 molecular sieve catalyst prepared using this sieve exhibits excellent catalytic performance, with NO reduction within a temperature window of 175–600 °C. x The conversion rate is higher than 85%.
[0042] This invention utilizes a special aluminum source and dual organic structure directing agents to prepare nano-SSZ-13 molecular sieves via a one-step crystallization method. The preparation process requires no seed crystals and involves controlling the ratio of the two organic structure directing agents. The synthesized nano-SSZ-13 molecular sieves exhibit high yield and pure crystalline phase. The synthesized nano-SSZ-13 molecular sieves demonstrate significant performance advantages as catalysts and adsorbents in the field of diesel vehicle exhaust treatment. Attached Figure Description
[0043] Figure 1 The X-ray diffraction (XRD) pattern of the sample in Example 1;
[0044] Figure 2 The image shown is a scanning electron microscope (SEM) image of the sample in Example 1.
[0045] Figure 3 The X-ray diffraction (XRD) pattern of the sample in Example 2;
[0046] Figure 4The image shown is a scanning electron microscope (SEM) image of the sample in Example 2.
[0047] Figure 5 The X-ray diffraction (XRD) pattern of the sample in Example 3;
[0048] Figure 6 The image shown is a scanning electron microscope (SEM) image of the sample in Example 3.
[0049] Figure 7 The X-ray diffraction (XRD) pattern of the sample in Example 4;
[0050] Figure 8 The image shown is a scanning electron microscope (SEM) image of the sample in Example 4.
[0051] Figure 9 The X-ray diffraction (XRD) pattern of the sample in Comparative Example 1 is shown.
[0052] Figure 10 The X-ray diffraction (XRD) pattern of the sample in Comparative Example 2 is shown.
[0053] Figure 11 The X-ray diffraction (XRD) pattern of the sample in Comparative Example 3 is shown.
[0054] Figure 12 The image shows a scanning electron microscope (SEM) image of the sample in Comparative Example 4.
[0055] Figure 13 The X-ray diffraction (XRD) pattern of the sample in Comparative Example 5 is shown. Detailed Implementation
[0056] In the context of this specification, the structure of the molecular sieve is determined by X-ray diffraction (XRD), which is measured using an X-ray powder diffractometer with a Cu-Kα ray source and a nickel filter. Before sample testing, the crystallinity of the molecular sieve sample is observed using a scanning electron microscope (SEM) to confirm that the sample contains only one type of crystal, i.e., the molecular sieve sample is a pure phase. XRD testing is then performed to ensure that there are no interfering peaks from other crystals in the diffraction pattern.
[0057] In the context of this specification, including in the following examples and comparative examples, the X-ray powder diffractometer used for the molecular sieves is a Panalytical X-PERPRO type X-ray powder diffractometer, used to analyze the phase composition of the samples, and a CuKα ray source. Nickel filter, 2θ scanning range 2~50°, operating voltage 40KV, current 40mA, scanning rate 10° / min.
[0058] In the context of this specification, including in the following examples and comparative examples, the scanning electron microscope (SEM) used for the molecular sieves is an S-4800II field emission scanning electron microscope. The molecular sieves were observed using this SEM at a magnification of 40,000x. A randomly selected field of view was used to calculate the average sum of the crystal sizes in that field of view, and this operation was repeated 10 times. The average sum of the 10 averages was taken as the crystal size.
[0059] In the context of this specification, including in the following examples and comparative examples, the pore volume, specific surface area, and external specific surface area of the molecular sieve were measured by the nitrogen physical adsorption-desorption method (BET method): the nitrogen physical adsorption-desorption isotherm of the molecular sieve was measured using a Micromeretic ASAP2020M physical adsorption instrument, and then calculated using the BET equation and t-plot equation. The experimental conditions for this molecular sieve were: measurement temperature -196°C; before measurement, the molecular sieve was heat-treated at 550°C in air for 6 hours, and then pretreated in vacuum at 350°C for 4 hours.
[0060] In the context of this specification, including in the following examples and comparative examples, the content of each element in the molecular sieve was determined by inductively coupled plasma atomic emission spectrometry (ICP) using a Varian 725-ES instrument. The analytical sample was dissolved in hydrofluoric acid prior to the test, and the elemental content was expressed in moles.
[0061] In the context of this specification, including in the following examples and comparative examples, the yield of molecular sieves refers to the percentage of the mass of the calcined sample relative to the sum of the masses of SiO2 and Al2O3 contained in the raw material.
[0062] In the context of this specification, including in the following examples and comparative examples, the catalyst performs the selective catalytic reduction of NO by NH3. x During the (NH3-SCR) reaction:
[0063] The weight hourly space velocity of the feedstock is 30,000–800,000 h⁻¹. 1 The feed mixture contains 500 ppm NO, 500 ppm NH3, 5% O2, 5% H2O, and N2 as a balance gas.
[0064] NO x The conversion rate % = (1 - (molar amount of NO in the effluent + molar amount of NO2 in the effluent) / (molar amount of NO in the feed + molar amount of NO2 in the feed)) × 100%.
[0065] N2 selectivity % = (1 - (molar amount of NO2 in the effluent + 2 × molar amount of N2O in the effluent) / (molar amount of NO in the feed + molar amount of NH3 in the feed - molar amount of NO in the effluent - molar amount of NH3 in the effluent)) × 100%.
[0066] The present invention will be further described in detail below with reference to the embodiments, but the present invention is not limited to these embodiments.
[0067] Example 1
[0068] 28.87 g of deionized water, 3.868 g of sodium aluminate (containing 40.5 wt% Al₂O₃ and 30.6 wt% Na₂O), 0.036 g of sodium hydroxide, 8.19 g of methyltriethylammonium hydroxide solution (containing 25.00 wt% methyltriethylammonium hydroxide) (organic structure directing agent a), 1.29 g of N,N,N-trimethyladamantane ammonium solution (containing 25.12 wt% N,N,N-trimethyladamantane ammonium) (organic structure directing agent b), and 23.07 g of silica sol (containing 40.0 wt% SiO₂) were stirred at room temperature for 4 hours to obtain a mixture. The final material ratio (molar ratio) was:
[0069] SiO2 / Al2O3 = 10;
[0070] NaOH / SiO2 = 0.24;
[0071] Methyltriethylammonium hydroxide / SiO2 = 0.10;
[0072] N,N,N-trimethyladamantane ammonium / SiO2 = 0.010;
[0073] H2O / SiO2 = 18.
[0074] The mixture was placed in a stainless steel reactor and heated to 160°C at 20 rpm for 3 days for crystallization. After crystallization, the mixture was filtered, washed, dried overnight in a 100°C oven, and then calcined in air at 550°C for 6 hours. The XRD pattern of the product is shown below. Figure 1 The sample shown is an SSZ-13 molecular sieve with a CHA structure and a yield of 88 wt%. The SiO2 / Al2O3 molar ratio of the molecular sieve was determined to be 9.6 using inductively coupled plasma atomic emission spectrometry (ICP). SEM images of the sample are shown below. Figure 2 As shown, the crystals exhibit a nanoparticle morphology with a size of 40 nm. The specific surface area of the sample is 753 m². 2 / gram, with an external specific surface area of 65 m² measured by the BET method. 2 / g; Total pore volume 0.42cm 3 / gram, micropore volume is 0.24 cm³ 3 / gram.
[0075] Example 2
[0076] 23.40 g of deionized water, 3.508 g of sodium aluminate (containing 40.5 wt% Al₂O₃ and 33 wt% Na₂O), 0.042 g of sodium hydroxide, 11.14 g of methyltriethylammonium hydroxide solution (containing 25.00 wt% methyltriethylammonium hydroxide) (organic structure directing agent a), 1.17 g of N,N,N-trimethyladamantane ammonium solution (containing 25.12 wt% N,N,N-trimethyladamantane ammonium) (organic structure directing agent b), and 20.93 g of silica sol (containing 40.0 wt% SiO₂) were stirred at room temperature for 4 hours to obtain a mixture. The final material ratio (molar ratio) was:
[0077] SiO2 / Al2O3 = 10;
[0078] NaOH / SiO2 = 0.26;
[0079] Methyltriethylammonium hydroxide / SiO2 = 0.15;
[0080] N,N,N-trimethyladamantane ammonium / SiO2 = 0.010;
[0081] H2O / SiO2 = 18.
[0082] The mixture was placed in a stainless steel reactor and heated at 160°C and 20 rpm for 3.5 days to crystallize. After crystallization, the mixture was filtered, washed, dried overnight in an oven at 100°C, and then calcined in air at 550°C for 6 hours. The XRD pattern of the product is shown below. Figure 3 The sample shown is an SSZ-13 molecular sieve with a CHA structure and a yield of 90 wt%. The SiO2 / Al2O3 molar ratio of the molecular sieve was determined to be 9.8 using inductively coupled plasma atomic emission spectrometry (ICP). The SEM image of the sample is shown below. Figure 4 As shown, the crystals exhibit a nanoparticle morphology with a size of 45 nm. The specific surface area of the sample is 762 m². 2 / gram, with an external specific surface area of 66 m² measured by the BET method. 2 / g; Total pore volume 0.41cm 3 / gram, micropore volume is 0.25 cm³ 3 / gram.
[0083] Example 3
[0084] 16.54 g of deionized water, 3.491 g of sodium aluminate (containing 40.5 wt% Al₂O₃ and 30.6 wt% Na₂O), 0.144 g of sodium hydroxide, 12.25 g of tetraethylammonium hydroxide solution (containing 25.00 wt% tetraethylammonium hydroxide) (organic structure directing agent a), 2.33 g of N,N,N-trimethyladamantane ammonium solution (containing 25.12 wt% N,N,N-trimethyladamantane ammonium) (organic structure directing agent b), and 20.83 g of silica sol (containing 40.0 wt% SiO₂) were stirred at room temperature for 4 hours to obtain a mixture. The final material ratio (molar ratio) was:
[0085] SiO2 / Al2O3 = 10;
[0086] NaOH / SiO2 = 0.26;
[0087] Tetraethylammonium hydroxide / SiO2 = 0.15;
[0088] N,N,N-Trimethyladamantaneammonium / SiO2 = 0.020;
[0089] H2O / SiO2 = 16.
[0090] The mixture was placed in a stainless steel reactor and heated at 160°C and 20 rpm for 2.5 days to crystallize. After crystallization, the mixture was filtered, washed, dried overnight in an oven at 100°C, and then calcined in air at 550°C for 6 hours. The XRD pattern of the product is shown below. Figure 5 The sample shown is an SSZ-13 molecular sieve with a CHA structure and a yield of 86 wt%. The SiO2 / Al2O3 molar ratio of the molecular sieve was determined to be 10.1 using inductively coupled plasma atomic emission spectrometry (ICP). The SEM image of the sample is shown below. Figure 6 As shown, the crystals exhibit a nanoparticle morphology with a size of 50 nm. The specific surface area of the sample is 733 m². 2 / gram, with an external specific surface area of 61 m² measured by the BET method. 2 / g; Total pore volume 0.45cm 3 / gram, micropore volume is 0.24 cm³ 3 / gram.
[0091] Example 4
[0092] 12.42 g of deionized water, 1.760 g of sodium aluminate (containing 42.5 wt% Al₂O₃ and 30.6 wt% Na₂O), 0.135 g of sodium hydroxide, 8.65 g of tetraethylammonium hydroxide solution (containing 25.00 wt% tetraethylammonium hydroxide) (organic structure directing agent a), 1.23 g of N,N,N-trimethyladamantane ammonium solution (containing 25.12 wt% N,N,N-trimethyladamantane ammonium) (organic structure directing agent b), and 11.02 g of silica sol (containing 40.0 wt% SiO₂) were stirred at room temperature for 4 hours to obtain a mixture. The final material ratio (molar ratio) was:
[0093] SiO2 / Al2O3 = 10;
[0094] NaOH / SiO2 = 0.28;
[0095] Tetraethylammonium hydroxide / SiO2 = 0.20;
[0096] N,N,N-Trimethyladamantaneammonium / SiO2 = 0.020;
[0097] H2O / SiO2 = 20.
[0098] The mixture was placed in a stainless steel reactor and heated to 160°C at 20 rpm for 3 days for crystallization. After crystallization, the mixture was filtered, washed, dried overnight in a 100°C oven, and then calcined in air at 550°C for 6 hours. The XRD pattern of the product is shown below. Figure 7 The sample shown is an SSZ-13 molecular sieve with a CHA structure and a yield of 87 wt%. The SiO2 / Al2O3 molar ratio of the molecular sieve was determined to be 9.8 using inductively coupled plasma atomic emission spectrometry (ICP). The SEM image of the sample is shown below. Figure 8 As shown, the crystals exhibit a nanoparticle morphology with a size of 50 nm. The specific surface area of the sample is 743 m². 2 / gram, with an external specific surface area of 68 m² measured by the BET method. 2 / g; Total pore volume 0.48cm 3 / gram, micropore volume is 0.25 cm³ 3 / gram.
[0099] Example 5
[0100] 7.66 g of deionized water, 2.201 g of sodium aluminate (containing 40.5 wt% Al₂O₃ and 30.6 wt% Na₂O), 0.021 g of sodium hydroxide, 3.73 g of methyltriethylammonium hydroxide solution (containing 25.00 wt% methyltriethylammonium hydroxide) (organic structure directing agent a), 1.18 g of N,N,N-trimethyladamantane ammonium solution (containing 25.12 wt% N,N,N-trimethyladamantane ammonium) (organic structure directing agent b), and 10.51 g of silica sol (containing 40.0 wt% SiO₂) were stirred at room temperature for 4 hours to obtain a mixture. The final material ratio (molar ratio) was:
[0101] SiO2 / Al2O3 = 8;
[0102] NaOH / SiO2 = 0.30;
[0103] Methyltriethylammonium hydroxide / SiO2 = 0.10;
[0104] N,N,N-Trimethyladamantaneammonium / SiO2 = 0.020;
[0105] H2O / SiO2 = 14.
[0106] The mixture was placed in a stainless steel reactor and heated to crystallize at 160°C and 10 rpm for 4 days. After crystallization, the mixture was filtered, washed, dried overnight in an oven at 100°C, and then calcined in air at 550°C for 6 hours. The XRD pattern of the obtained product was similar to... Figure 1 Similarly, the SSZ-13 molecular sieve has a CHA structure, with a yield of 85 wt%. The SiO2 / Al2O3 molar ratio of the molecular sieve was determined to be 8.2 using inductively coupled plasma atomic emission spectrometry (ICP). The SEM image of the sample is similar to... Figure 2 Similarly, the crystals exhibit a nanoparticle morphology with a size of 50 nm. The specific surface area of the sample is 703 m². 2 / gram, with an external specific surface area of 58 m² measured by the BET method. 2 / g; Total pore volume 0.43cm 3 / gram, micropore volume is 0.25 cm³ 3 / gram.
[0107] Example 6
[0108] 273.29 g of deionized water, 24.872 g of sodium aluminate (containing 40.5 wt% Al₂O₃ and 30.6 wt% Na₂O), 7.821 g of sodium hydroxide, 104.75 g of tetraethylammonium hydroxide solution (containing 25.00 wt% tetraethylammonium hydroxide) (organic structure directing agent a), 14.96 g of N,N,N-trimethyladamantane ammonium solution (containing 25.12 wt% N,N,N-trimethyladamantane ammonium) (organic structure directing agent b), and 178.07 g of silica sol (containing 40.0 wt% SiO₂) were stirred at room temperature for 4 hours to obtain a mixture. The final material ratio (molar ratio) was:
[0109] SiO2 / Al2O3 = 12;
[0110] NaOH / SiO2 = 0.36;
[0111] Tetraethylammonium hydroxide / SiO2 = 0.15;
[0112] N,N,N-trimethyladamantane ammonium / SiO2 = 0.015;
[0113] H2O / SiO2 = 22.
[0114] The mixture was placed in a stainless steel reactor and heated at 160°C and 100 rpm for 5 days to crystallize. After crystallization, it was filtered, washed, dried overnight in a 100°C oven, and then calcined in air at 550°C for 6 hours. The XRD pattern of the product obtained was similar to... Figure 1 Similarly, the SSZ-13 molecular sieve, with a CHA structure, was obtained in a yield of 91 wt%. Inductively coupled plasma atomic emission spectrometry (ICP) determined the SiO2 / Al2O3 molar ratio of the molecular sieve to be 11.7. The SEM image of the sample is similar to... Figure 2 Similarly, the crystals exhibit a nanoparticle morphology with a size of 55 nm. The sample has a specific surface area of 682 m². 2 / gram, with an external specific surface area of 72 m² measured by the BET method. 2 / g; Total pore volume 0.45cm 3 / gram, micropore volume is 0.23 cm³ 3 / gram.
[0115] Example 7
[0116] A mixture was prepared by stirring 457.76 g of deionized water, 25.450 g of sodium aluminate (containing 40.5 wt% Al₂O₃ and 30.6 wt% Na₂O), 9.944 g of sodium hydroxide, 71.45 g of tetraethylammonium hydroxide solution (containing 25.00 wt% tetraethylammonium hydroxide) (organic structure directing agent a), 10.21 g of N,N,N-trimethyladamantane ammonium solution (containing 25.12 wt% N,N,N-trimethyladamantane ammonium) (organic structure directing agent b), and 227.75 g of silica sol (containing 40.0 wt% SiO₂) at room temperature for 4 hours. The final material ratio (molar ratio) was:
[0117] SiO2 / Al2O3 = 15;
[0118] NaOH / SiO2 = 0.32;
[0119] Tetraethylammonium hydroxide / SiO2 = 0.08;
[0120] N,N,N-Trimethyladamantaneammonium / SiO2 = 0.008;
[0121] H2O / SiO2 = 24.
[0122] The mixture was placed in a stainless steel reactor and heated to crystallize at 165°C and 80 rpm for 3 days. After crystallization, it was filtered, washed, dried in an oven at 100°C overnight, and then calcined in air at 550°C for 6 hours. The XRD pattern of the product obtained was similar to... Figure 1 Similarly, the SSZ-13 molecular sieve, with a CHA structure, was obtained in a yield of 84 wt%. The SiO2 / Al2O3 molar ratio of the molecular sieve was determined to be 15.2 using inductively coupled plasma atomic emission spectrometry (ICP). The SEM image of the sample is similar to... Figure 2 Similarly, the crystals exhibit a nanoparticle morphology with a size of 60 nm. The sample has a specific surface area of 705 m². 2 / gram, with an external specific surface area of 76 m² measured by the BET method. 2 / g; Total pore volume 0.48cm 3 / gram, micropore volume is 0.25 cm³ 3 / gram.
[0123] Example 8
[0124] A mixture was prepared by stirring 523.12 g of deionized water, 37.631 g of sodium aluminate (containing 40.5 wt% Al₂O₃ and 30.6 wt% Na₂O), 7.049 g of sodium hydroxide, 254.90 g of methyltriethylammonium hydroxide solution (containing 25.00 wt% methyltriethylammonium hydroxide) (organic structure directing agent a), 24.15 g of N,N,N-trimethyladamantane ammonium solution (containing 25.12 wt% N,N,N-trimethyladamantane ammonium) (organic structure directing agent b), and 359.22 g of silica sol (containing 40.0 wt% SiO₂) at room temperature for 4 hours. The final material ratio (molar ratio) was:
[0125] SiO2 / Al2O3 = 16;
[0126] NaOH / SiO2 = 0.22;
[0127] Methyltriethylammonium hydroxide / SiO2 = 0.20;
[0128] N,N,N-trimethyladamantane ammonium / SiO2 = 0.012;
[0129] H2O / SiO2 = 22.
[0130] The mixture was placed in a stainless steel reactor and heated at 155°C and 120 rpm for 4.5 days to crystallize. After crystallization, the mixture was filtered, washed, dried overnight in an oven at 100°C, and then calcined in air at 550°C for 6 hours. The XRD pattern of the product obtained was similar to... Figure 1 Similarly, the SSZ-13 molecular sieve, with a CHA structure, was obtained in a yield of 88 wt%. Inductively coupled plasma atomic emission spectrometry (ICP) determined the SiO2 / Al2O3 molar ratio of the molecular sieve to be 16.3. SEM images of the samples are shown below. Figure 2 Similarly, the crystals exhibit a nanoparticle morphology with a size of 45 nm. The sample has a specific surface area of 694 m². 2 / gram, with an external specific surface area of 59 m² measured by the BET method. 2 / g; Total pore volume 0.47cm 3 / gram, micropore volume is 0.24 cm³ 3 / gram.
[0131] Example 9
[0132] 18.94 g of deionized water, 0.629 g of sodium aluminate (containing 38.5 wt% Al₂O₃ and 30.6 wt% Na₂O), 0.271 g of sodium hydroxide, 2.53 g of methyltriethylammonium hydroxide solution (containing 25.00 wt% methyltriethylammonium hydroxide) (organic structure directing agent a), 0.72 g of N,N,N-trimethyladamantane ammonium solution (containing 25.12 wt% N,N,N-trimethyladamantane ammonium) (organic structure directing agent b), and 7.13 g of silica sol (containing 40.0 wt% SiO₂) were stirred at room temperature for 4 hours to obtain a mixture. The final material ratio (molar ratio) was:
[0133] SiO2 / Al2O3 = 20;
[0134] NaOH / SiO2 = 0.26;
[0135] Methyltriethylammonium hydroxide / SiO2 = 0.10;
[0136] N,N,N-trimethyladamantane ammonium / SiO2 = 0.018;
[0137] H2O / SiO2 = 30.
[0138] The mixture was placed in a stainless steel reactor and heated at 170°C and 20 rpm for 2.5 days to crystallize. After crystallization, it was filtered, washed, dried overnight in an oven at 100°C, and then calcined in air at 550°C for 6 hours. The XRD pattern of the product obtained was similar to... Figure 1 Similarly, the SSZ-13 molecular sieve, with a CHA structure, was obtained in a yield of 87 wt%. Inductively coupled plasma atomic emission spectrometry (ICP) determined the SiO2 / Al2O3 molar ratio of the molecular sieve to be 20.4. The SEM image of the sample is shown below. Figure 2 Similarly, the crystals exhibit a nanoparticle morphology with a size of 40 nm. The sample has a specific surface area of 781 m². 2 / gram, with an external specific surface area of 72 m² measured by the BET method. 2 / g; Total pore volume 0.46cm 3 / gram, micropore volume is 0.23 cm³ 3 / gram.
[0139] Example 10
[0140] 34.69 g of deionized water, 1.128 g of sodium aluminate (containing 40.5 wt% Al₂O₃ and 30.6 wt% Na₂O), 0.613 g of sodium hydroxide, 5.73 g of methyltriethylammonium hydroxide solution (containing 25.00 wt% methyltriethylammonium hydroxide) (organic structure directing agent a), 2.26 g of N,N,N-trimethyladamantane ammonium solution (containing 25.12 wt% N,N,N-trimethyladamantane ammonium) (organic structure directing agent b), and 16.15 g of silica sol (containing 40.0 wt% SiO₂) were stirred at room temperature for 4 hours to obtain a mixture. The final material ratio (molar ratio) was:
[0141] SiO2 / Al2O3 = 24;
[0142] NaOH / SiO2 = 0.24;
[0143] Methyltriethylammonium hydroxide / SiO2 = 0.10;
[0144] N,N,N-Trimethyladamantaneammonium / SiO2 = 0.025;
[0145] H2O / SiO2 = 26.
[0146] The mixture was placed in a stainless steel reactor and heated to crystallize at 160°C and 30 rpm for 3 days. After crystallization, it was filtered, washed, dried in an oven at 100°C overnight, and then calcined in air at 550°C for 6 hours. The XRD pattern of the obtained product was similar to... Figure 1 Similarly, the SSZ-13 molecular sieve has a CHA structure, with a yield of 90 wt%. The SiO2 / Al2O3 molar ratio of the molecular sieve was determined to be 24.1 using inductively coupled plasma atomic emission spectrometry (ICP). The SEM image of the sample is similar to... Figure 2 Similarly, the crystals exhibit a nanoparticle morphology with a size of 35 nm. The sample has a specific surface area of 713 m². 2 / gram, with an external specific surface area of 95 m² measured by the BET method. 2 / g; Total pore volume 0.40 cm³ 3 / gram, micropore volume is 0.25 cm³ 3 / gram.
[0147] Comparative Example 1
[0148] The material ratio is the same as in Example 1, except that N,N,N-trimethyladamantane ammonium (SDA2) is not added. The final material ratio (molar ratio) is:
[0149] SiO2 / Al2O3 = 10;
[0150] NaOH / SiO2 = 0.24;
[0151] Methyltriethylammonium hydroxide / SiO2 = 0.10;
[0152] N,N,N-Trimethyladamantaneammonium / SiO2=0;
[0153] H2O / SiO2 = 18.
[0154] The mixture was placed in a stainless steel reactor and heated at 160°C and 20 rpm for 3 days to crystallize. After crystallization, the mixture was filtered, washed, and dried overnight in an oven at 100°C. The XRD pattern of the obtained product is shown below. Figure 9 As shown, the sample has a MOR structure, not a CHA structure molecular sieve.
[0155] Comparative Example 2
[0156] The material ratio is the same as in Example 1, except that methyltriethylammonium hydroxide or tetraethylammonium hydroxide (SDA1) is not added, and tetramethylammonium hydroxide is added as SDA1. The final material ratio (molar ratio) is:
[0157] SiO2 / Al2O3 = 10;
[0158] NaOH / SiO2 = 0.24;
[0159] Tetramethylammonium hydroxide / SiO2 = 0.10;
[0160] N,N,N-Trimethyladamantaneammonium / SiO2=0.01;
[0161] H2O / SiO2 = 18.
[0162] The mixture was placed in a stainless steel reactor and heated at 160°C and 20 rpm for 3 days to crystallize. After crystallization, the mixture was filtered, washed, and dried overnight in an oven at 100°C. The XRD pattern of the obtained product is shown below. Figure 10 As shown, the sample is an Omega molecular sieve, not a CHA structure molecular sieve.
[0163] Comparative Example 3
[0164] The material ratio is the same as in Example 1, except that a larger amount of sodium aluminate is used. The final material ratio (molar ratio) is:
[0165] SiO2 / Al2O3 = 6;
[0166] NaOH / SiO2 = 0.38;
[0167] Methyltriethylammonium hydroxide / SiO2 = 0.10;
[0168] N,N,N-Trimethyladamantaneammonium / SiO2=0.01;
[0169] H2O / SiO2 = 18.
[0170] The mixture was placed in a stainless steel reactor and heated at 160°C and 20 rpm for 3 days to crystallize. After crystallization, the mixture was filtered, washed, and dried overnight in an oven at 100°C. The XRD pattern of the obtained product is shown below. Figure 11 As shown, the sample is a symbiotic structure of CHA molecular sieve and P zeolite, and is not a pure phase CHA molecular sieve.
[0171] Comparative Example 4
[0172] The material ratio is the same as in Example 1, except that methyltriethylammonium hydroxide or tetraethylammonium hydroxide (SDA1) is not added, and N,N,N-trimethyladamantane ammonium (SDA1) in the same molar amount as in Example 1 is added. The final material ratio (molar ratio) is:
[0173] SiO2 / Al2O3 = 10;
[0174] NaOH / SiO2 = 0.24;
[0175] N,N,N-Trimethyladamantaneammonium / SiO2 = 0.11;
[0176] H2O / SiO2 = 18.
[0177] The mixture was placed in a stainless steel reactor and heated to 160°C at 20 rpm for 3 days for crystallization. After crystallization, the mixture was filtered, washed, dried overnight in a 100°C oven, and then calcined in air at 550°C for 6 hours. The XRD pattern of the obtained product was similar to... Figure 1 Similarly, the SSZ-13 molecular sieve has a CHA structure. The SEM image of the sample is shown below. Figure 12 As shown, the crystals are relatively large, with an average particle size of 500 nm. The specific surface area of the sample is 623 m². 2 / gram, with an external specific surface area of 16 m² measured by the BET method. 2 / g; Total pore volume 0.29 cm³ 3 / gram, micropore volume is 0.25 cm³ 3 / gram.
[0178] Comparative Example 5
[0179] The material ratio is the same as in Example 1, except that the added sodium aluminate contains different contents of Al2O3 and Na2O (containing 45.6% by weight of Al2O3 and 36.2% by weight of Na2O). The raw materials are prepared in the same amount of substances.
[0180] The mixture was placed in a stainless steel reactor and heated to crystallize at 160°C with a stirring speed of 20 rpm for 3 days. After crystallization, the mixture was filtered, washed, and dried overnight in an oven at 100°C. The XRD pattern of the obtained product is shown below. Figure 13 As shown, the sample is not a pure-phase CHA structure, but a mixture of CHA and GIS molecular sieves.
[0181] Examples n to 20
[0182] The sodium-type SSZ-13 molecular sieves synthesized in Examples 1-10 were subjected to ammonium ion exchange with 0.2 mol / L NH4NO3 solution (mass ratio 1:20) at 65°C for 3 hours, followed by centrifugation and washing. The ammonium ion exchange was repeated once. The resulting samples were then subjected to copper ion exchange with 0.02 mol / L Cu(NO3)2 solution (mass ratio 1:20) at 80°C for 12 hours, followed by centrifugation and washing. The copper ion exchange was repeated once. The samples were dried overnight in an oven at 100°C and then calcined in air at 550°C for 6 hours to obtain the Cu-SSZ-13 molecular sieve samples.
[0183] The calcined Cu-SSZ-13 molecular sieve powder sample was crushed, and 1.0 g of the 20-40 mesh particle size fraction was sieved and placed into a fixed-bed reactor to evaluate the catalyst activity at a space velocity of 200,000 h⁻¹. 1 The NH3-SCR reaction activity of the catalyst was tested at 150–600 °C. Table 1 shows the NO content of the catalyst at different reaction temperatures. x The conversion rate of NO in the catalyst within a temperature window of 175–600 °C x The conversion rate is higher than 85%, and the selectivity of the product N2 exceeds 98%.
[0184] Comparative Examples 5-6
[0185] Similar to Examples 11-20, the catalysts obtained after treating the molecular sieves synthesized in Comparative Examples 4 and 5 were subjected to the NH3-SCR reaction. The catalyst activities are shown in Table 1. The NO content of the catalysts was measured within a temperature window of 500-600°C. x The conversion rate is less than 85%.
[0186] Table 1. Catalyst performance results for Examples 11-20 and Comparative Examples 5-6
[0187]
[0188]
[0189] The specific embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combining the various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.
Claims
1. A nano-SSZ-13 molecular sieve, characterized in that, The nano-SSZ-13 molecular sieve has a crystal particle size of 30~80nm and a SiO2 / Al2O3 molar ratio of 7.6~28.0; the total specific surface area of the nano-SSZ-13 molecular sieve is not less than 550 m². 2 / gram, external specific surface area not less than 50 m² 2 / g; the total pore volume of the nano-SSZ-13 molecular sieve is not less than 0.30 cm³. 3 / gram, micropore volume not less than 0.20 cm³ 3 / gram.
2. The nano-SSZ-13 molecular sieve according to claim 1, characterized in that, The nano-SSZ-13 molecular sieve has a crystal particle size of 35~75nm and a SiO2 / Al2O3 molar ratio of 8.0~24.
5.
3. The nano-SSZ-13 molecular sieve according to claim 1, characterized in that, The total specific surface area of the nano-SSZ-13 molecular sieve is 550~900 m². 2 / gram; external specific surface area is 50~150 m² 2 / g; and / or, the total pore volume of the nano-SSZ-13 molecular sieve is 0.30~0.80 cm³. 3 / g; micropore volume is 0.20~0.30 cm³. 3 / gram.
4. A method for preparing the nano-SSZ-13 molecular sieve according to any one of claims 1-3, comprising the following steps: A silicon source, an aluminum source, an alkali source, organic structure directing agent a, organic structure directing agent b, and water are mixed and crystallized to obtain the nano-SSZ-13 molecular sieve; and optionally, the obtained nano-SSZ-13 molecular sieve is calcined; wherein the aluminum source is sodium aluminate, and the content of Al2O3 in the sodium aluminate is 38%~43% by weight, and the content of Na2O is 30%~33% by weight; The added silicon source (SiO2), aluminum source (Al2O3), alkali source, organic structure directing agent a (SDA1), organic structure directing agent b (SDA2), and water are in a molar ratio of SiO2:Al2O3:alkali source:SDA1:SDA2:H2O = 1:0.036~0.130:0.20~0.40:0.08~0.20:0.005~0.035:12~50. The organic structure directing agent a is selected from at least one of tetraethylammonium hydroxide and methyltriethylammonium hydroxide; the organic structure directing agent b is N,N,N-trimethyladamantane ammonium.
5. The preparation method according to claim 4, characterized in that, The molar ratio is SiO2:Al2O3:alkali source:SDA1:SDA2:H2O=1:0.040~0.125:0.22~0.38:0.08~0.20:0.008~0.030:14~40.
6. The preparation method according to claim 4, characterized in that, The silicon source is silica sol; the alkali source is selected from at least one inorganic alkali with alkali metal or alkaline earth metal as cations.
7. The preparation method according to claim 4, characterized in that, The reaction mixture was crystallized at 130-180°C for 1.5-7.0 days.
8. The preparation method according to claim 7, characterized in that, The reaction mixture was crystallized at 140-170°C for 2.0-6.0 days.
9. The preparation method according to claim 4, characterized in that, The crystallization process of the reaction mixture is a dynamic crystallization by rotation or stirring, with a rotation or stirring speed of 10~300 rpm.
10. The preparation method according to claim 9, characterized in that, The rotation or stirring speed is 10~150 rpm.
11. A nano-SSZ-13 molecular sieve composition, characterized in that, The nano SSZ-13 molecular sieve composition comprises nano SSZ-13 molecular sieve prepared according to any one of claims 1 to 3 or according to any one of claims 4 to 10, and a binder.
12. The use of the nano SSZ-13 molecular sieve according to any one of claims 1 to 3, or the nano SSZ-13 molecular sieve prepared according to any one of claims 4 to 10, or the nano SSZ-13 molecular sieve composition according to claim 11 as a catalyst.
13. The application according to claim 12, characterized in that, The application of the nano SSZ-13 molecular sieve as a catalyst in diesel vehicle exhaust treatment.