Regulation and verification method for location and occupation of rare earth ions in rare earth Y-type molecular sieve
Through the combination of ion exchange, thermal shock and low-dose 4D-STEM technology, the atomic precision regulation and verification of rare earth ions in rare earth Y-type molecular sieve is achieved, solving the problem of placement and placeholding of rare earth ions in rare earth Y-type molecular sieve, and improving catalyst performance and verification accuracy.
Patent Information
- Application Number
- CN202510744351.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-05
- Publication Date
- 2025-08-08
AI Technical Summary
It is difficult for the prior art to achieve atomic precise placement and placeholding regulation and verification of rare earth ions in rare earth Y-type molecular sieves. Traditional methods lack effective means, resulting in limited improvement in catalyst performance.
The regulation steps of ion exchange-gas purge-risking-efficient thermal shock-annealing treatment are adopted, and combined with the verification method of low-dose 4D-STEM acquisition-super-resolved stacked phase reconstruction-phase contrast statistical analysis, the precise placement and placeholding regulation of rare earth ions in the Y-type molecular sieve is achieved by controlling physical parameters.
It realizes atomic precision regulation of rare earth ions in Y-type molecular sieve, improves the structural order and functionality of the catalyst, shortens the material preparation cycle, improves the objective quantification ability and research credibility of verification results, and is suitable for a variety of rare earth modified molecular sieve systems.
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Figure CN120446114A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the field of molecular sieve modification and characterization technology, and in particular to a method for regulating and verifying the placement and occupancy of rare earth ions in rare earth Y-type molecular sieves. Background Art
[0002] Y-type molecular sieve is a crystalline aluminosilicate zeolite material with large pore size, which is widely used in petrochemical industry, environmental protection and other fields. Figure 1 As shown, Y-type zeolites are composed of supercages with the largest pores, sodalite cages with medium pores, and hexagonal prisms with the smallest pores. The sodalite cages and hexagonal prisms are collectively referred to as small cages. To further enhance their functionality and stability, Y-type zeolites are often modified by introducing rare earth elements. In the fluid catalytic cracking (FCC) process, Y-type zeolites (LaY) modified with the rare earth lanthanum (La) are widely used as the primary active component of the catalyst. The introduction of lanthanum not only enhances the acidity and catalytic activity of the zeolite but also significantly improves its thermal stability and resistance to hydrothermal aging. In addition to lanthanum, rare earth elements such as cerium (Ce) and neodymium (Nd) are also commonly used in Y-type zeolite modification research. Cerium, due to its excellent redox properties, helps improve the catalyst's resistance to carbon deposition, while neodymium further enhances the structural strength and high-temperature stability of the zeolite, thereby extending the catalyst's service life under harsh operating conditions.
[0003] The placement and occupancy of rare earth ions in the pores of rare earth Y-type zeolites determine the activity and stability of Y-type zeolite catalysts, but their control and verification methods are often very limited. Traditional catalyst control methods are often based on simple "matching" strategies, screening catalysts through a "combinatorial" research model, lacking the ability to precisely control the placement and occupancy of rare earth ions in the pores at the atomic level (placement refers to the specific area where rare earth ions are deposited or embedded in the material, and occupancy refers to the occupancy of rare earth ions in the crystal lattice at the location). A more important reason for the lack of such precise control methods comes from the challenge of precise atomic-level structural verification. Traditional infrared, Raman and other spectroscopic techniques cannot obtain direct and reliable structural information related to rare earth ions, while traditional transmission electron microscopy techniques are often unable to obtain atomic-level precise rare earth ion placement and occupancy information because the molecular sieve material is extremely susceptible to electron irradiation damage. Therefore, developing an integrated atomic-level control and verification method for rare earth ions in rare earth Y-type zeolites is the key to achieving precise control of rare earth placement and occupancy. Summary of the Invention
[0004] In view of the shortcomings of the existing technology, the present invention provides a method for regulating and verifying the placement and occupancy of rare earth ions in rare earth Y-type molecular sieves.
[0005] To achieve the above objectives, the present invention is implemented through the following technical solutions:
[0006] The present invention discloses a method for regulating and verifying the placement and occupancy of rare earth ions in a rare earth Y-type molecular sieve, comprising the following steps:
[0007] (1) performing ion exchange on a rare earth salt solution and a NaY type molecular sieve to obtain a Y type molecular sieve containing rare earth ions, and drying the resulting product to obtain a dry precursor;
[0008] (2) Place the dried precursor in a high-throughput electrothermal reaction platform, purge the sample with nitrogen, and circulate the gas at the same time; then start the plasma generator, set the ignition power to 50W, and the ignition time to 0-20min;
[0009] (3) Controlling the amplitude and width of the thermal vibration pulses of the high-throughput electrothermal reaction platform, as well as the relaxation time, to obtain rare earth Y-type molecular sieves under the cumulative bombardment of multiple thermal vibration pulses;
[0010] (4) annealing the rare earth Y-type molecular sieve and performing low-dose 4D-STEM acquisition after the annealing;
[0011] (5) Using electron stacking reconstruction technology to obtain phase contrast atomic-level electron microscopy images of rare earth Y-type molecular sieves;
[0012] (6) using a cross-correlation algorithm to obtain all regional images similar to the characteristic regional image in the electron microscope image, and superimposing all regional images to obtain a characteristic average image, and judging the placement of rare earth ions based on the contrast within the Y-type molecular sieve structural unit in the periodic characteristic average image;
[0013] The intensity of rare earth ions in the sodalite cage and hexagonal prism of the rare earth Y-type molecular sieve in the characteristic average image, as well as the intensity of the adjacent oxygen atom column, were measured respectively; based on this, the relative intensity I of the rare earth ions in the sodalite cage was calculated. 方 and the relative intensity of rare earth ions in the hexagonal prism I 六 ;
[0014] Based on the structural model, a series of electron microscope images of the placement and occupation of different numbers of rare earth ions in the rare earth Y-type molecular sieve sodalite cages and hexagonal prisms were simulated; the corresponding I 方 with I 六 , taking the occupancy of rare earth ions as the independent variable, the relative intensity I 方 with I 六 are the dependent variables, and I 方 with I 六 The fitting curve of the change of occupancy; Finally, the experimentally measured I 方 with I 六 Substituting them into the relative intensity fitting curve equation, the occupancy of rare earth ions can be obtained.
[0015] Preferably, in step (1), the mass ratio of the rare earth salt to the NaY molecular sieve powder is 0.5-2:1.
[0016] Preferably, in step (1), during the ion exchange process, the rare earth salt solution passes through the NaY molecular sieve at a uniform rate and circulates; the flow rate of the rare earth salt solution through the NaY molecular sieve is 20-40 ml / min, and the circulation time of the rare earth salt solution is 12-24 hours.
[0017] Preferably, in step (2), the flow rate of the circulating gas is 1-3 ml / s.
[0018] Preferably, in step (3), the amplitude of the thermal vibration pulse is 400-700°C, the width of the thermal vibration pulse is 2-4s, wherein the heating time period is 1s, the holding time and the cooling time are 1-3s in total; the relaxation time of the thermal vibration pulse is 0-10s, and the number of bombardments of the thermal vibration pulse is 3-7 times.
[0019] Preferably, in step (4), the annealing temperature is 20-700° C. and the annealing time is 0-96 hours.
[0020] Preferably, in step (6), the formula of the cross-correlation algorithm is as follows:
[0021]
[0022] in, is the mean of the feature region image, variables x and y are the pixel coordinates in the feature region image, is the mean of the sub-image of the electron microscope image at position (u, v). The output of the formula is [-1, 1], where 1 indicates a perfect match.
[0023] Preferably, in step (6), the selection of the characteristic region includes the positions of both sodalite cages and hexagonal prisms, and the adjacent oxygen atom columns are oxygen atom columns at the O2 position of the Y-type molecular sieve.
[0024] Preferably, in step (6), I 方 = intensity of rare earth ions on the rare earth Y-type molecular sieve sodalite cage / intensity of the adjacent oxygen atom column; I 六 =Intensity of rare earth ions on the hexagonal prism of rare earth Y-type molecular sieve / intensity of the adjacent oxygen atom column.
[0025] Preferably, the rare earth element in the rare earth salt solution is any one of La, Ce, and Nd.
[0026] The present invention has the following beneficial effects:
[0027] 1. The present invention is based on the rare earth ions (such as La3+ ) will migrate in super cages, sodalite cages and hexagonal prisms. Through the control steps of "ion exchange-gas purge-violent thermal shock-annealing treatment" and the verification steps of "low-dose 4D-STEM acquisition-super-resolution stacking phase reconstruction-phase contrast statistical analysis", the atomic-level rare earth (such as La) Y-type molecular sieve rare earth ions (such as La) are realized. 3+ ) in the pores. Physical parameters such as ion exchange concentration, thermal pulse amplitude and width, treatment atmosphere and flow rate, and plasma power were used to control the placement and occupancy ratio of rare earth ions in different locations within rare earth Y-type molecular sieve supercages, sodalite cages, and hexagonal prisms.
[0028] 2. The synthesis rate of the present invention is extremely fast and the process efficiency is high: the high-throughput electrothermal reaction platform can complete rapid heating of 400-700°C in a few seconds. Compared with traditional heat treatment methods, it greatly shortens the material preparation cycle, improves experimental efficiency and material response speed, and is more suitable for industrial rapid screening and mass production.
[0029] 3. The present invention can precisely regulate the placement and occupancy of rare earth ions: it can achieve fine regulation of the placement and occupancy behavior of rare earth ions in small cage positions (such as sodalite cages and hexagonal prisms) in the Y-type molecular sieve structure, thereby improving the structural orderliness and functionality of the material.
[0030] 4. This invention utilizes advanced imaging techniques, resulting in objective and quantifiable results: It effectively overcomes the limitations of conventional transmission electron microscope imaging of electron-beam-sensitive materials, improving image clarity and resolution. Furthermore, by quantifying the intensity of rare earth ions within the Y-type molecular sieve structure, the verification results are objectively quantifiable, enhancing research credibility and reproducibility.
[0031] 5. This method is highly scalable and applicable to other rare-earth-modified molecular sieve systems: This method is not only applicable to the study of LaY molecular sieves but can also be extended to the structural elucidation and control of other types of rare-earth-modified molecular sieves (such as CeY and NdY) or electron-beam-sensitive materials, demonstrating its versatility and scalability.
[0032] 6. This invention contributes to the development of high-performance catalytic materials: by precisely controlling the placement and occupancy of rare earth ions in the molecular sieve framework, it helps to further regulate the acidity, thermal stability and distribution of catalytic active sites of the material, providing an important structural basis for the development of new and efficient catalysts. BRIEF DESCRIPTION OF THE DRAWINGS
[0033] Figure 1 Schematic diagram of the structure of Y-type molecular sieve;
[0034] Figure 2 It is the technical roadmap of the present invention;
[0035] Figure 3 This is the XRD test result of LaY prepared in Example 1, proving the successful preparation of LaY;
[0036] Figure 4 This is an atomic-level electron microscope image of LaY prepared in Example 1;
[0037] Figure 5 is the feature area image in Example 1;
[0038] Figure 6 All region images similar to the characteristic region image are identified using a cross-correlation algorithm in the LaY atomic-scale electron microscope image in Example 1;
[0039] Figure 7 For simulation of different numbers of La based on the structural model 3+ Electron microscope images and corresponding intensity curves of the placement and occupation of sodalite cages and hexagonal prisms in LaY type molecular sieves;
[0040] Figure 8 For La 3+ The position of the independent variable is the relative strength I 方 with I 六 As the dependent variable, plot I 方 with I 六 Fitting curve and fitting equation with changes in space occupancy;
[0041] Figure 9 is the characteristic average image in Example 1 and the La in the sodalite cage and hexagonal prism 3+ Strength curve of
[0042] Figure 10 is the characteristic average image in Example 2 and the La in the sodalite cage and hexagonal prism 3+ Strength curve of
[0043] Figure 11 is the characteristic average image in Example 3 and the La in the sodalite cage and hexagonal prism 3+ Strength curve of
[0044] Figure 12 is the characteristic average image in Example 4 and the La in the sodalite cage and hexagonal prism 3+ Strength curve of
[0045] Figure 13 is the characteristic average image in Example 5 and the La in the sodalite cage and hexagonal prism 3+ Strength curve of
[0046] Figure 14 is the characteristic average image in Example 6 and the La in the sodalite cage and hexagonal prism 3+ The intensity curve. DETAILED DESCRIPTION
[0047] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.
[0048] Unless otherwise specified, the technical means used in the embodiments are conventional means well known to those skilled in the art.
[0049] refer to Figure 2 As shown, the present invention discloses a method for regulating and verifying the placement and occupancy of rare earth ions in an atomic-level precise rare earth Y-type molecular sieve, comprising the following steps:
[0050] (1) Ion exchange
[0051] (1.1) A rare earth salt is added to deionized water to prepare a rare earth salt solution. The rare earth element may be La, Ce, or Nd. For example, La has a rare earth salt of lanthanum chloride hexahydrate (LaCl3·6H2O).
[0052] (1.2) Evenly pack NaY molecular sieve powder into a glass exchange column and secure both ends with glass wool to prevent loss, ensuring a tight, bubble-free packing channel; use deionized water to pass through the glass column at a low flow rate to fully wet the molecular sieve; pass a prepared rare earth salt solution (such as LaCl3 solution) through the column containing the NaY molecular sieve at a uniform flow rate, ensuring that the solution flows slowly and steadily throughout the packing layer; keep the entire column warm in a water bath at approximately 85°C to enhance ion diffusion and exchange efficiency; use a peristaltic pump to circulate the rare earth salt solution for a certain period of time to increase the exchange rate;
[0053] The mass ratio of lanthanum chloride hexahydrate to NaY molecular sieve powder is 0.5-2:1. The rare earth salt solution is passed through the column containing the NaY molecular sieve at a uniform flow rate of 20-40 ml / min. The peristaltic pump circulates the rare earth salt solution for 12-24 hours.
[0054] (1.3) Disassemble the column and remove the rare earth ions (such as La 3+ ) was taken out, rinsed with deionized water and then collected; the obtained precursor sample was placed in an oven at 50° C. and dried for 12 hours to obtain a dry precursor;
[0055] (2) Gas purge
[0056] The dried precursor was placed in a high-throughput electrothermal reaction platform. The sample was purged with nitrogen and the chamber was set to a gas circulation mode. The plasma generator was then activated with a starting power of 50 W and a starting time of 0-20 minutes. The circulating gas flow rate was 1-3 ml / s.
[0057] (3) Severe thermal shock
[0058] Controlling the amplitude and width of the thermal pulses on the high-throughput electrothermal reaction platform, as well as the relaxation time, ultimately allows for the production of rare earth Y-type molecular sieves (such as LaY) through cumulative thermal pulse bombardment.
[0059] The thermal pulse amplitude is 400-700°C. The thermal pulse width is 2-4 seconds, with the heating period being 1 second, and the hold and cooling periods being 1-3 seconds in total. The thermal pulse relaxation time is 0-10 seconds, and the number of thermal pulse bombardments is 3-7.
[0060] (4) Annealing
[0061] The obtained rare earth Y-type molecular sieve (such as LaY) is annealed, and the rare earth (such as La) is jointly regulated by steps (3) and (3). 3+ ) The placement and occupation of ions; the annealing temperature is 20-700°C and the time is 0-96 hours.
[0062] (5) Low-dose 4D-STEM acquisition
[0063] (5.1) Ultrasonic dispersion of the prepared rare earth Y molecular sieve powder sample in a volatile solvent such as ethanol;
[0064] (5.2) The sample is then evenly distributed on a carbon film-supported copper grid using a drop coating method. After drying naturally, it is placed in the sample holder of a transmission electron microscope and inserted into the microscope chamber.
[0065] (5.3) Select an empty area without sample interference to align the center of the transmitted electron beam spot with the direct electron detector. Adjust the lens system and camera parameters to ensure that the center of the transmitted electron beam spot is accurately aligned with the center of the detector.
[0066] (5.4) After alignment is completed, move the field of view to the rare earth Y-type molecular sieve sample area and select a representative area with clear crystals as the 4D-STEM scanning range;
[0067] (5.5) Strictly control the electron beam conditions to avoid radiation damage to the sample during the collection process. The total electron beam dose is controlled to less than The low dose range is used to ensure data quality while preserving the original structure of the sample as much as possible.
[0068] (6) Super-resolution stacked phase reconstruction
[0069] After obtaining the 4D-STEM data of the rare earth Y-type molecular sieve, the phase contrast atomic-level electron microscope image of the rare earth Y-type molecular sieve was obtained using the multi-layer electron stacking reconstruction technique.
[0070] The 4D-STEM data of the rare earth Y-type molecular sieve is a four-dimensional data cube I (x, y, kx, ky), which includes both a two-dimensional spatial scanning position (x, y) and a two-dimensional diffraction pattern (kx, ky).
[0071] The specific steps of the super-resolution stack phase reconstruction include: 1) modeling of multi-layer material function and probe function: considering that the sample has a finite thickness, in the multi-layer electron stack reconstruction algorithm, the sample is discretized into several thin layers along the electron beam propagation direction (z-axis), and each layer is approximately a two-dimensional complex amplitude transmission function; 2) forward propagation: the propagation process of the electron wave adopts far-field propagation; 3) wavefront modulation and reverse propagation: the diffraction pattern collected in the experiment is used to modulate the electron wavefront while using reverse far-field propagation; 4) using the gradient descent method to update the material function; 5) using the gradient descent method to update the probe function; 6) using the gradient descent method to correct the probe position.
[0072] (7) Rare earth ions (such as La 3+ ) Statistical analysis of placement and occupancy
[0073] 1) A representative periodic region image in a phase contrast atomic-level electron microscope image of a rare earth Y-type molecular sieve is intercepted as a characteristic region image; the characteristic region is selected to include a position containing both a sodalite cage and a hexagonal prism.
[0074] 2) Using the cross-correlation algorithm, all the regional images similar to the characteristic regional image in the electron microscope image are obtained, and all the regional images are superimposed to obtain the periodic characteristic average image. The rare earth ions (such as La) are judged according to the contrast within the Y-type molecular sieve structural unit in the periodic characteristic average image. 3+ ) placement of ions;
[0075] 3) Use intensity extraction tools (such as DigitalMicrograph software) to measure the rare earth ions (such as La) in the rare earth Y-type molecular sieve sodalite cage and hexagonal prism positions in the periodic feature average image. 3+ ) (respectively denoted as I1 and I2), and the intensity of the adjacent oxygen atom column (denoted as I3). The adjacent oxygen atom column is the oxygen atom column at the O2 position of the Y-type molecular sieve.
[0076] 4) Based on this, calculate the rare earth ions (such as La3+ ) in the sodalite cage relative strength I 方 =I1 / I3 and La in the hexagonal prism 3+ The relative strength I 六 =I2 / I3;
[0077] 5) Based on the structural model, a series of simulations with different amounts of rare earth ions (such as La 3+ ) Electron microscope images of the placement and occupation of sodalite cages and hexagonal prisms in rare earth (such as La) Y-type molecular sieves.
[0078] 6) Calculate the corresponding I 方 with I 六 , with rare earth ions (such as La 3+ ) is the independent variable, the relative strength I 方 with I 六 are the dependent variables, and I 方 with I 六 The fitting curve of the change of occupancy; Finally, the experimentally measured I 方 with I 六 Substitute the relative intensity fitting curve equation to obtain the rare earth ions (such as La 3+ ) placeholder.
[0079] In order to eliminate the influence of brightness and contrast, the cross-correlation algorithm uses normalized cross-correlation. The specific mathematical formula is as follows:
[0080]
[0081] in, is the mean of the feature region image, variables x and y are the pixel coordinates in the feature region image, is the mean of the sub-image of the electron microscope image at position (u, v). The output of the formula is [-1, 1], where 1 indicates a perfect match.
[0082] The present invention will be further described below with reference to specific embodiments.
[0083] The NaY molecular sieves used in the following examples were purchased from Raodong (Liaoning) New Materials Co., Ltd.
[0084] Example 1
[0085] A method for regulating and verifying the placement and occupancy of rare earth ions in atomically precise rare earth Y-type molecular sieves includes the following steps:
[0086] (1) Ion exchange
[0087] Weigh 0.15g LaCl3·6H2O, add it to 20mL deionized water, stir thoroughly until it is completely dissolved, and prepare a lanthanum chloride solution. Evenly fill 0.3g of NaY molecular sieve powder into a glass exchange column and fix both ends with glass wool to prevent loss. At the same time, ensure that the filling is tight and there is no bubble channel. Use deionized water to pass through the glass column at a low flow rate to fully wet the molecular sieve. Pass the prepared LaCl3 solution through the column containing NaY molecular sieve at a flow rate of 20ml / min, and keep the solution flowing slowly and steadily through the entire packing layer. Keep the entire column warm in a water bath at about 85℃, and use a circulating peristaltic pump to circulate the LaCl3 solution for 12 hours. Disassemble the column and remove the La-containing 3+ The Y-type molecular sieve filler was taken out, rinsed with deionized water and then collected. The obtained precursor sample was placed in an oven at 50° C. and dried for 12 hours to obtain a dry precursor.
[0088] (2) Gas purge
[0089] The obtained solid precursor was added to the high-throughput electrothermal reaction platform, and the air in the high-throughput electrothermal reaction platform was purged using a nitrogen atmosphere. At the same time, the box was set to work in a gas circulation mode with a flow rate of 1 ml / s.
[0090] (3) Severe thermal shock
[0091] The thermal pulse amplitude of the high-throughput electrothermal reaction platform was set to 400°C, the thermal pulse width was 2s, the heating period was 1s, the holding time and the cooling time were 1s in total; the relaxation time was 0s, and LaY was obtained by bombarding the thermal pulse cycle three times under this setting. The XRD test results of the prepared LaY are shown in the figure. Figure 3 As shown, the successful preparation of LaY is proved. The atomic level electron microscope image of LaY is shown in Figure 4 shown.
[0092] (4) Low-dose 4D-STEM acquisition
[0093] (4.1) Ultrasonic dispersion of the prepared LaY molecular sieve powder sample in a volatile solvent such as ethanol;
[0094] (4.2) The sample is then evenly distributed on a carbon film-supported copper grid using a drop coating method. After drying naturally, it is placed in the sample holder of a transmission electron microscope and inserted into the microscope chamber.
[0095] (4.3) Select an empty area without sample interference to align the center of the transmitted electron beam spot with the direct electron detector. Adjust the lens system and camera parameters to ensure that the center of the transmitted electron beam spot is accurately aligned with the center of the detector.
[0096] (4.4) After alignment is completed, move the field of view to the LaY molecular sieve sample area and select a representative area with clear crystals as the 4D-STEM scanning range;
[0097] (4.5) Strictly control the electron beam conditions to avoid radiation damage to the sample during the collection process. The total electron beam dose is controlled to less than The low dose range is used to ensure data quality while preserving the original structure of the sample as much as possible.
[0098] (5) Super-resolution stacked phase reconstruction
[0099] After obtaining the 4D-STEM data of LaY, the electron stacking reconstruction technology of LaY type molecular sieve was used to obtain the electron microscope image of LaY type molecular sieve at the atomic level.
[0100] (6)La 3+ Statistical analysis of placement and occupancy
[0101] The cross-correlation algorithm is used to analyze the characteristic areas in the electron microscope image of LaY molecular sieve and perform superposition processing to obtain the characteristic average image. 3+ The position and intensity of ions can accurately identify the location and occupancy of metal ions in Y-type molecular sieves.
[0102] Figure 5 This is the feature area image in Example 1. Figure 6 These are all region images similar to the characteristic region image in the electron microscope image of the atomic-level LaY molecular sieve in Example 1. Figure 9 is the characteristic average image in Example 1 and the La in the sodalite cage and hexagonal prism 3+ According to the intensity curve, we can get I1=0.31,I2=0.11,I3=0.10,I 方 =3.10, I 六 =1.10. Figure 8 Middle I 方 with I 六 Follow La 3+ The fitting curve and fitting equation of the occupancy change show that La 3+ The occupancy rate in sodalite cages is 0.59, and the occupancy rate in hexagonal prisms is 0.14.
[0103] Example 2
[0104] A method for regulating and verifying the placement and occupancy of rare earth ions in atomically precise rare earth Y-type molecular sieves includes the following steps:
[0105] (1) Ion exchange
[0106] Weigh 0.45g LaCl3·6H2O, add it to 20mL deionized water, stir thoroughly until it is completely dissolved, and prepare a lanthanum chloride solution. Evenly fill 0.3g of NaY molecular sieve powder into a glass exchange column and fix both ends with glass wool to prevent loss. At the same time, ensure that the filling is tight and there is no bubble channel. Use deionized water to pass through the glass column at a low flow rate to fully wet the molecular sieve. Pass the prepared LaCl3 solution through the column containing NaY molecular sieve at a flow rate of 40ml / min, and keep the solution flowing slowly and steadily through the entire packing layer. Keep the entire column warm in a water bath at about 85℃, and use a circulating peristaltic pump to circulate the LaCl3 solution for 24 hours. Disassemble the column and remove the La-containing 3+ The Y-type molecular sieve filler was taken out, rinsed with deionized water and then collected. The obtained precursor sample was placed in an oven at 50° C. and dried for 12 hours to obtain a dry precursor.
[0107] (2) Gas purge
[0108] The obtained solid precursor was added to the high-throughput electrothermal reaction platform, and the air in the high-throughput electrothermal reaction platform was purged in a nitrogen atmosphere. At the same time, the box was set to work in a gas circulation flow mode with a flow rate of 3 ml / s. Then, a plasma generator was used to clean the sample contaminants, and the ignition power was set to 50 W and the ignition time was set to 10 min.
[0109] (3) Severe thermal shock
[0110] The thermal vibration pulse amplitude of the high-throughput electrothermal reaction platform was set to 400°C and the thermal vibration pulse width was set to 2s, where the heating period was 1s, the holding time and the cooling time were 1s in total; the relaxation time was 0s. Under this setting, LaY was obtained by three thermal pulse cycle bombardments.
[0111] (4) Annealing
[0112] The obtained LaY was annealed at a temperature of 120° C. for 2 hours.
[0113] (5) Low-dose 4D-STEM acquisition
[0114] (5.1) Ultrasonic dispersion of the annealed LaY molecular sieve powder sample in a volatile solvent such as ethanol;
[0115] (5.2) The sample is then evenly distributed on a carbon film-supported copper grid using a drop coating method. After drying naturally, it is placed in the sample holder of a transmission electron microscope and inserted into the microscope chamber.
[0116] (5.3) Select an empty area without sample interference to align the center of the transmitted electron beam spot with the direct electron detector. Adjust the lens system and camera parameters to ensure that the center of the transmitted electron beam spot is accurately aligned with the center of the detector.
[0117] (5.4) After alignment is completed, move the field of view to the LaY molecular sieve sample area and select a representative area with clear crystals as the 4D-STEM scanning range;
[0118] (5.5) Strictly control the electron beam conditions to avoid radiation damage to the sample during the collection process. The total electron beam dose is controlled to less than The low dose range is used to ensure data quality while preserving the original structure of the sample as much as possible.
[0119] (6) Super-resolution stacked phase reconstruction
[0120] After obtaining 4D-STEM data, electron stacking reconstruction technology was used to obtain an atomic-level electron microscope image of LaY molecular sieve. The cross-correlation algorithm was used to analyze the characteristic areas in the electron microscope image of LaY molecular sieve and perform superposition processing to obtain a characteristic average image. By measuring the La in the characteristic average image, the La 3+ The position and intensity of ions can accurately identify the location and occupancy of metal ions in Y-type molecular sieves.
[0121] Figure 10 is the characteristic average image in Example 2 and the La in the sodalite cage and hexagonal prism 3+ According to the intensity curve, we can get I1=0.29,I2=0.12,I3=0.10,I 方 =2.90, I 六 =1.20. Figure 8 Middle I 方 with I 六 Follow La 3+ The fitting curve and fitting equation of the occupancy change show that La 3+ The occupancy rate in sodalite cages is 0.54, and the occupancy rate in hexagonal prisms is 0.15.
[0122] Example 3
[0123] A method for regulating and verifying the placement and occupancy of rare earth ions in atomically precise rare earth Y-type molecular sieves includes the following steps:
[0124] (1) Ion exchange
[0125] Weigh 0.60g LaCl3·6H2O, add it to 20mL deionized water, stir thoroughly until it is completely dissolved, and prepare a lanthanum chloride solution. Evenly fill 0.3g of NaY molecular sieve powder into a glass exchange column and fix both ends with glass wool to prevent loss. At the same time, ensure that the filling is tight and there is no bubble channel. Use deionized water to pass through the glass column at a low flow rate to fully wet the molecular sieve. Pass the prepared LaCl3 solution through the column containing NaY molecular sieve at a flow rate of 40ml / min, and keep the solution flowing slowly and steadily through the entire packing layer. Keep the entire column warm in a water bath at about 85℃, and use a circulating peristaltic pump to circulate the LaCl3 solution for 24 hours. Disassemble the column and remove the La-containing 3+ The Y-type molecular sieve filler was taken out, rinsed with deionized water and then collected. The obtained precursor sample was placed in an oven at 50° C. and dried for 12 hours to obtain a dry precursor.
[0126] (2) Gas purge
[0127] The obtained solid precursor was added to the high-throughput electrothermal reaction platform, and the air in the high-throughput electrothermal reaction platform was purged in a nitrogen atmosphere. At the same time, the box was set to work in a gas circulation flow mode with a flow rate of 3 ml / s. Then, a plasma generator was used to clean the sample contaminants, and the ignition power was set to 50 W and the ignition time was set to 10 min.
[0128] (3) Severe thermal shock
[0129] The thermal vibration pulse amplitude of the high-throughput electrothermal reaction platform was set to 400°C and the thermal vibration pulse width was set to 4s, with the heating period being 1s, the holding time and the cooling time being 3s in total; the relaxation time was 0s. Under this setting, LaY was obtained by 7 rounds of thermal pulse bombardment.
[0130] (4) Annealing
[0131] The obtained LaY was annealed at a temperature of 400° C. for 24 hours.
[0132] (5) Low-dose 4D-STEM acquisition
[0133] The specific process is the same as Example 2.
[0134] (6) Super-resolution stacked phase reconstruction
[0135] After obtaining 4D-STEM data, electron stacking reconstruction technology was used to obtain an atomic-level electron microscope image of LaY molecular sieve. The cross-correlation algorithm was used to analyze the characteristic areas in the electron microscope image of LaY molecular sieve and perform superposition processing to obtain a characteristic average image. By measuring the La in the characteristic average image, the La 3+The position and intensity of ions can accurately identify the location and occupancy of metal ions in Y-type molecular sieves.
[0136] Figure 11 is the characteristic average image in Example 3 and the La in the sodalite cage and hexagonal prism 3+ According to the intensity curve, we can get I1=0.42, I2=0.07, I3=0.11, I 方 =3.82, I 六 =0.64. Figure 8 Middle I 方 with I 六 Follow La 3+ The fitting curve and fitting equation of the occupancy change show that La 3+ The occupancy rate in sodalite cages is 0.80, and the occupancy rate in hexagonal prisms is 0.03.
[0137] Example 4
[0138] A method for regulating and verifying the placement and occupancy of rare earth ions in atomically precise rare earth Y-type molecular sieves includes the following steps:
[0139] (1) Ion exchange
[0140] Weigh 0.60g LaCl3·6H2O, add it to 20mL deionized water, stir thoroughly until it is completely dissolved, and prepare a lanthanum chloride solution. Evenly fill 0.3g of NaY molecular sieve powder into a glass exchange column and fix both ends with glass wool to prevent loss. At the same time, ensure that the filling is tight and there is no bubble channel. Use deionized water to pass through the glass column at a low flow rate to fully wet the molecular sieve. Pass the prepared LaCl3 solution through the column containing NaY molecular sieve at a flow rate of 40ml / min, and keep the solution flowing slowly and steadily through the entire packing layer. Keep the entire column warm in a water bath at about 85℃, and use a circulating peristaltic pump to circulate the LaCl3 solution for 24 hours. Disassemble the column and remove the La-containing 3+ The Y-type molecular sieve filler was taken out, rinsed with deionized water and then collected. The obtained precursor sample was placed in an oven at 50° C. and dried for 12 hours to obtain a dry precursor.
[0141] (2) Gas purge
[0142] The obtained solid precursor was added to the high-throughput electrothermal reaction platform, and the air in the high-throughput electrothermal reaction platform was purged in a nitrogen atmosphere. At the same time, the box was set to work in a gas circulation flow mode with a flow rate of 3 ml / s. Then, a plasma generator was used to clean the sample contaminants, and the ignition power was set to 50 W and the ignition time was set to 20 min.
[0143] (3) Severe thermal shock
[0144] The thermal vibration pulse amplitude of the high-throughput electrothermal reaction platform was set to 550°C and the thermal vibration pulse width was set to 2s, where the heating period was 1s, the holding time and the cooling time were 1s in total; the relaxation time was 0s. Under this setting, LaY was obtained by 3 rounds of thermal pulse bombardment.
[0145] (4) Annealing
[0146] The obtained LaY was annealed at a temperature of 550° C. for 48 hours.
[0147] (5) Low-dose 4D-STEM acquisition
[0148] The specific process is the same as Example 2.
[0149] (6) Super-resolution stacked phase reconstruction
[0150] After obtaining 4D-STEM data, electron stacking reconstruction technology was used to obtain an atomic-level electron microscope image of LaY molecular sieve. The cross-correlation algorithm was used to analyze the characteristic areas in the electron microscope image of LaY molecular sieve and perform superposition processing to obtain a characteristic average image. By measuring the La in the characteristic average image, the La 3+ The position and intensity of ions can accurately identify the placement and occupancy of metal ions in Y-type molecular sieves.
[0151] Figure 12 is the characteristic average image in Example 4 and the La in the sodalite cage and hexagonal prism 3+ According to the intensity curve, we can get I1=0.17,I2=0.15,I3=0.10,I 方 =1.70, I 六 =1.50. Figure 8 Middle I 方 with I 六 Follow La 3+ The fitting curve and fitting equation of the occupancy change show that La 3+ The occupancy rate in sodalite cages is 0.20, and the occupancy rate in hexagonal prisms is 0.24.
[0152] Example 5
[0153] A method for regulating and verifying the placement and occupancy of rare earth ions in atomically precise rare earth Y-type molecular sieves includes the following steps:
[0154] (1) Ion exchange
[0155] Weigh 0.60g LaCl3·6H2O, add it to 20mL deionized water, stir thoroughly until it is completely dissolved, and prepare a lanthanum chloride solution. Evenly fill 0.3g of NaY molecular sieve powder into a glass exchange column and fix both ends with glass wool to prevent loss. At the same time, ensure that the filling is tight and there is no bubble channel. Use deionized water to pass through the glass column at a low flow rate to fully wet the molecular sieve. Pass the prepared LaCl3 solution through the column containing NaY molecular sieve at a flow rate of 40ml / min, and keep the solution flowing slowly and steadily through the entire packing layer. Keep the entire column warm in a water bath at about 85℃, and use a circulating peristaltic pump to circulate the LaCl3 solution for 24 hours. Disassemble the column and remove the La-containing 3+ The Y-type molecular sieve filler was taken out, rinsed with deionized water and then collected. The obtained precursor sample was placed in an oven at 50° C. and dried for 12 hours to obtain a dry precursor.
[0156] (2) Gas purge
[0157] The obtained solid precursor was added to the high-throughput electrothermal reaction platform, and the air in the high-throughput electrothermal reaction platform was purged in a nitrogen atmosphere. At the same time, the box was set to work in a gas circulation flow mode with a flow rate of 3 ml / s. Then, a plasma generator was used to clean the sample contaminants, and the ignition power was set to 50 W and the ignition time was set to 20 min.
[0158] (3) Severe thermal shock
[0159] The thermal vibration pulse amplitude of the high-throughput electrothermal reaction platform was set to 550°C and the thermal vibration pulse width was set to 3s, where the heating period was 1s, the holding time and the cooling time were 2s in total; the relaxation time was 0s. Under this setting, LaY was obtained by 5 rounds of thermal pulse bombardment.
[0160] (4) Annealing
[0161] The obtained LaY was annealed at a temperature of 550° C. for 96 hours.
[0162] (5) Low-dose 4D-STEM acquisition
[0163] The specific process is the same as Example 2.
[0164] (6) Super-resolution stacked phase reconstruction
[0165] After obtaining 4D-STEM data, electron stacking reconstruction technology was used to obtain an atomic-level electron microscope image of LaY molecular sieve. The cross-correlation algorithm was used to analyze the characteristic areas in the electron microscope image of LaY molecular sieve and perform superposition processing to obtain a characteristic average image. By measuring the La in the characteristic average image, the La 3+The position and intensity of ions can accurately identify the location and occupancy of metal ions in Y-type molecular sieves.
[0166] Figure 13 is the characteristic average image in Example 5 and the La in the sodalite cage and hexagonal prism 3+ According to the intensity curve, we can get I1=0.20,I2=0.23,I3=0.10,I 方 =2.00, I 六 =2.30. Figure 8 Middle I 方 with I 六 Follow La 3+ The fitting curve and fitting equation of the occupancy change show that La 3+ The occupancy rate in sodalite cages is 0.28, and the occupancy rate in hexagonal prisms is 0.39.
[0167] Example 6
[0168] A method for regulating and verifying the placement and occupancy of rare earth ions in atomically precise rare earth Y-type molecular sieves includes the following steps:
[0169] (1) Ion exchange
[0170] Weigh 0.60g LaCl3·6H2O, add it to 20mL deionized water, stir thoroughly until it is completely dissolved, and prepare a lanthanum chloride solution. Evenly fill 0.3g of NaY molecular sieve powder into a glass exchange column and fix both ends with glass wool to prevent loss. At the same time, ensure that the filling is tight and there is no bubble channel. Use deionized water to pass through the glass column at a low flow rate to fully wet the molecular sieve. Pass the prepared LaCl3 solution through the column containing NaY molecular sieve at a flow rate of 40ml / min, and keep the solution flowing slowly and steadily through the entire packing layer. Keep the entire column warm in a water bath at about 85℃, and use a circulating peristaltic pump to circulate the LaCl3 solution for 24 hours. Disassemble the column and remove the La-containing 3+ The Y-type molecular sieve filler was taken out, rinsed with deionized water and then collected. The obtained precursor sample was placed in an oven at 50° C. and dried for 12 hours to obtain a dry precursor.
[0171] (2) Gas purge
[0172] The obtained solid precursor was added to the high-throughput electrothermal reaction platform, and the air in the high-throughput electrothermal reaction platform was purged in a nitrogen atmosphere. At the same time, the box was set to work in a gas circulation flow mode with a flow rate of 3 ml / s. Then, a plasma generator was used to clean the sample contaminants, and the ignition power was set to 50 W and the ignition time was set to 20 min.
[0173] (3) Severe thermal shock
[0174] The thermal vibration pulse amplitude of the high-throughput electrothermal reaction platform was set to 700°C and the thermal vibration pulse width was set to 4s, with the heating period being 1s, the holding time and the cooling time being 3s in total; the relaxation time was 0s. Under this setting, LaY was obtained by 7 rounds of thermal pulse bombardment.
[0175] (4) Annealing
[0176] The obtained LaY was annealed at a temperature of 700° C. for 96 hours.
[0177] (5) Low-dose 4D-STEM acquisition
[0178] The specific process is the same as Example 2.
[0179] (6) Super-resolution stacked phase reconstruction
[0180] After obtaining 4D-STEM data, electron stacking reconstruction technology was used to obtain an atomic-level electron microscope image of LaY molecular sieve. The cross-correlation algorithm was used to analyze the characteristic areas in the electron microscope image of LaY molecular sieve and perform superposition processing to obtain a characteristic average image. By measuring the La in the characteristic average image, the La 3+ The position and intensity of ions can accurately identify the location and occupancy of metal ions in Y-type molecular sieves.
[0181] Figure 14 The characteristic average image in Example 6 and the La in the sodalite cage and hexagonal prism 3+ According to the intensity curve, we can get I1=0.24,I2=0.30,I3=0.10,I 方 =2.40, I 六 =3.00. Figure 8 Middle I 方 with I 六 Follow La 3+ The fitting curve and fitting equation of the occupancy change show that La 3+ The occupancy rate in sodalite cages is 0.39, and the occupancy rate in hexagonal prisms is 0.54.
[0182] The embodiments described above are merely descriptions of preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by persons skilled in the art should fall within the scope of protection defined by the claims of the present invention.
Claims
1. A method for regulating and verifying the placement and occupancy of rare earth ions in a rare earth Y-type molecular sieve, characterized by: The following steps are involved: (1) performing ion exchange on a rare earth salt solution and a NaY type molecular sieve to obtain a Y type molecular sieve containing rare earth ions, and drying the resulting product to obtain a dry precursor; (2) Place the dried precursor in a high-throughput electrothermal reaction platform, purge the sample with nitrogen, and circulate the gas at the same time; then start the plasma generator, set the ignition power to 50W, and the ignition time to 0-20min; (3) Controlling the amplitude and width of the thermal vibration pulses of the high-throughput electrothermal reaction platform, as well as the relaxation time, to obtain rare earth Y-type molecular sieves under the cumulative bombardment of multiple thermal vibration pulses; (4) annealing the rare earth Y-type molecular sieve and performing low-dose 4D-STEM acquisition after the annealing; (5) Using electron stacking reconstruction technology to obtain phase contrast atomic-level electron microscopy images of rare earth Y-type molecular sieves; (6) using a cross-correlation algorithm to obtain all regional images similar to the characteristic regional image in the electron microscope image, and superimposing all regional images to obtain a characteristic average image, and judging the placement of rare earth ions based on the contrast within the Y-type molecular sieve structural unit in the periodic characteristic average image; The intensity of rare earth ions in the sodalite cage and hexagonal prism of the rare earth Y-type molecular sieve in the characteristic average image, as well as the intensity of the adjacent oxygen atom column, were measured respectively; based on this, the relative intensity I of the rare earth ions in the sodalite cage was calculated. 方 and the relative intensity of rare earth ions in the hexagonal prism I 六 ; Based on the structural model, a series of electron microscope images of the placement and occupation of different numbers of rare earth ions in the rare earth Y-type molecular sieve sodalite cages and hexagonal prisms were simulated; the corresponding I 方 with I 六 , taking the occupancy of rare earth ions as the independent variable, the relative intensity I 方 with I 六 are the dependent variables, and I 方 with I 六 The fitting curve of the change of occupancy; Finally, the experimentally measured I 方 with I 六 Substituting them into the relative intensity fitting curve equation, the occupancy of rare earth ions can be obtained.
2. The method for regulating and verifying the placement and occupancy of rare earth ions in a rare earth Y-type molecular sieve according to claim 1, characterized in that: In step (1), the mass ratio of the rare earth salt to the NaY molecular sieve powder is 0.5-2:
1.
3. The method for regulating and verifying the placement and occupancy of rare earth ions in a rare earth Y-type molecular sieve according to claim 1 or 2, characterized in that: In step (1), during the ion exchange process, the rare earth salt solution passes through the NaY molecular sieve at a uniform rate and circulates; the flow rate of the rare earth salt solution through the NaY molecular sieve is 20-40 ml / min, and the rare earth salt solution circulates for 12-24 hours.
4. The method for regulating and verifying the placement and occupancy of rare earth ions in a rare earth Y-type molecular sieve according to claim 1, characterized in that: In step (2), the flow rate of the gas circulation is 1-3 ml / s.
5. The method for regulating and verifying the placement and occupancy of rare earth ions in a rare earth Y-type molecular sieve according to claim 1, characterized in that: In step (3), the amplitude of the thermal vibration pulse is 400-700°C, the width of the thermal vibration pulse is 2-4s, wherein the heating time period is 1s, the holding time and the cooling time are 1-3s in total; the relaxation time of the thermal vibration pulse is 0-10s, and the number of bombardments of the thermal vibration pulse is 3-7 times.
6. The method for regulating and verifying the placement and occupancy of rare earth ions in a rare earth Y-type molecular sieve according to claim 1, characterized in that: In step (4), the annealing temperature is 20-700° C. and the annealing time is 0-96 hours.
7. The method for regulating and verifying the placement and occupancy of rare earth ions in a rare earth Y-type molecular sieve according to claim 1, characterized in that: In step (6), the formula of the cross-correlation algorithm is as follows: in, is the mean of the feature region image, variables x and y are the pixel coordinates in the feature region image, is the mean of the sub-image of the electron microscope image at position (u, v). The output of the formula is [-1, 1], where 1 indicates a perfect match.
8. The method for regulating and verifying the placement and occupancy of rare earth ions in a rare earth Y-type molecular sieve according to claim 1, characterized in that: In step (6), the selection of the characteristic region includes the positions of the sodalite cage and the hexagonal prism; the adjacent oxygen atom column is the oxygen atom column at the O2 position of the Y-type molecular sieve.
9. The method for regulating and verifying the placement and occupancy of rare earth ions in a rare earth Y-type molecular sieve according to claim 8, characterized in that: In step (6), I 方 = intensity of rare earth ions on the rare earth Y-type molecular sieve sodalite cage / intensity of the adjacent oxygen atom column; I 六 =Intensity of rare earth ions on the hexagonal prism of rare earth Y-type molecular sieve / intensity of the adjacent oxygen atom column.
10. The method for regulating and verifying the placement and occupancy of rare earth ions in a rare earth Y-type molecular sieve according to claim 1, characterized in that: The rare earth element in the rare earth salt solution is any one of La, Ce and Nd.