Visual characterization method for accessibility and acid density of solid-phase material

Abstract

The invention provides a visual characterization method for accessibility and acid density of a solid-phase material, which comprises the following steps: 1) carrying out oligomerization reaction on a probe molecule solution in a solid-phase material to be characterized to obtain a reaction system comprising N reactants, N being greater than or equal to 2; the polymerization degrees of the reactants are different; 2) acquiring a fluorescence emission image of the reaction system; and 3) characterizing the accessibility and the acid density according to the fluorescence emission image. According to the visual characterization method for the accessibility and the acid density of the solid-phase material, provided by the invention, the acid center in the solid-phase material can be positioned, and the accessibility and the acid density of the solid-phase material can be quantitatively analyzed; and meanwhile, the method has the advantages of few used solid-phase materials, small damage to the solid-phase materials, rapidness, good repeatability, simple process and the like.

Description

Technical Field

[0001] This invention relates to a method for visually characterizing the accessibility and acid density of solid materials, belonging to the field of petrochemical catalyst research. Background Technology

[0002] Acid properties (acid strength, acid type, acid density, and accessibility of acid centers, etc.) are core factors affecting the catalytic performance of catalysts and catalytic materials in the fluidized catalytic cracking industry. Conducting research on catalyst acidity, especially the development of analytical methods, plays an important technical supporting role in the research and development of new catalytic cracking materials.

[0003] Traditional methods for characterizing the acidity of catalytic materials or catalysts mainly include ammonia temperature-programmed desorption technology and pyridine adsorption in-situ infrared spectroscopy. Ammonia temperature-programmed desorption technology (Zeolites, 1984, 4(1): 9-14.) can only roughly calculate the acid density of the catalyst, but cannot calculate the accessibility of the catalyst; the limitation of pyridine adsorption in-situ infrared spectroscopy (Microporous and Mesoporous Materials. 2004, 71: 157–166.) is that it can only characterize the Brønsted acid and Lewis acid contained in the catalyst, but cannot accurately observe the location of the acidic active centers in the Brønsted acid and Lewis acid in the catalyst, and the distribution of the acidic active centers in the catalyst.

[0004] Therefore, scientifically and intuitively characterizing the pore structure of catalytic materials or catalysts, especially their accessibility and acid density, is a key technical challenge in the field of catalysis research. Summary of the Invention

[0005] This invention provides a visual characterization method for the accessibility and acid density of solid materials. This method can locate the acid centers in solid materials and perform quantitative analysis of the accessibility and acid density of solid materials. It also has the advantages of using less solid material, causing less damage to solid materials, being fast, having good repeatability, and having a simple process.

[0006] This invention provides a method for visually characterizing the accessibility and acid density of solid materials, comprising the following steps:

[0007] 1) The probe molecule solution is subjected to oligomerization in the solid material to be characterized to obtain a reaction system comprising N reactants, where N≥2; each reactant has a different degree of polymerization.

[0008] 2) Obtain fluorescence emission images of the reaction system;

[0009] 3) The accessibility and acid density are characterized based on the fluorescence emission image.

[0010] The method for visually characterizing the accessibility and acid density of solid materials as described above, wherein characterizing the accessibility and acid density based on the fluorescence emission image includes:

[0011] The acid density of the solid material to be characterized is determined based on the number of fluorescence emission sites in the fluorescence emission image.

[0012] The accessibility of the solid material to be characterized is determined based on the number of fluorescence emission sites of each of the N reactants in the fluorescence emission image.

[0013] The above-described method for visually characterizing the accessibility and acid density of solid materials, wherein the reaction system comprises a dimer with a degree of polymerization of 2 and a trimer with a degree of polymerization of 3;

[0014] The accessibility of the solid material to be characterized is determined by the ratio of the number of fluorescence emission sites in the trimer to the total number of fluorescence emission sites in the dimer and trimer.

[0015] The method for visually characterizing the accessibility and acid density of solid-phase materials as described above, wherein acquiring the fluorescence emission image of the reaction system includes:

[0016] Based on the fluorescence excitation wavelengths of the N reactants, excitable light is emitted from the reaction system to obtain M fluorescence emission images of the reactants, where M≥2;

[0017] The fluorescence emission images of the M reactants are combined to obtain the fluorescence emission image of the reaction system.

[0018] The method for visually characterizing the accessibility and acid density of solid materials as described above, wherein the probe molecule is selected from at least one of p-methoxystyrene, furfuryl alcohol, and thiophene; and / or, the solvent is selected from at least one of n-pentane, ethanol, and n-octane.

[0019] The method for visually characterizing the accessibility and acid density of solid materials as described above, wherein the molar concentration of the probe molecule solution is 1 × 10⁻⁶. -10 -1×10 -3 mol / L.

[0020] The above-described method for visually characterizing the accessibility and acid density of solid materials, wherein the solid material is an FCC catalyst, and the FCC catalyst includes one of ZSM molecular sieve and Y-type molecular sieve.

[0021] The method for visually characterizing the accessibility and acid density of solid materials as described above, wherein the mass ratio of the probe molecule solution to the solid material is 0.0001-0.01.

[0022] The method for visually characterizing the accessibility and acid density of solid materials as described above further includes, before causing the probe molecule solution to undergo an oligomerization reaction in the solid material to be characterized, calcining the solid material to be characterized at an ambient temperature of not less than 500°C for 4-8 hours.

[0023] The above-described method for visual characterizing the accessibility and acid density of solid materials, wherein the reaction time of the oligomerization reaction is 30-90 min.

[0024] This invention utilizes the targeted recognition of probe molecules and acid centers, along with the fluorescence properties of probe molecule polymers, to enable a visual characterization method that can quickly and intuitively locate acid centers and calculate accessibility and acid density. Furthermore, the process is simple, requires minimal solid material for characterization, causes minimal damage to solid materials, and offers high repeatability. Attached Figure Description

[0025] Figure 1 This describes a two-dimensional Gaussian fitting procedure for processing fluorescence emission images.

[0026] Figure 2 This is a composite processing procedure for fluorescence emission images;

[0027] Figure 3 The fluorescence emission image is from Example 1;

[0028] Figure 4 This is the result of fitting the fluorescence emission image of Example 1;

[0029] Figure 5 The fluorescence emission image is from Example 2;

[0030] Figure 6 This is the result of fitting the fluorescence emission image of Example 2;

[0031] Figure 7 The fluorescence emission image is from Example 3;

[0032] Figure 8 This is the result of fitting the fluorescence emission image of Example 3;

[0033] Figure 9 The fluorescence emission image is from Example 4;

[0034] Figure 10 This is the result of fitting the fluorescence emission image of Example 4;

[0035] Figure 11 The fluorescence emission image is from Example 5;

[0036] Figure 12This is the result of fitting the fluorescence emission image of Example 5;

[0037] Figure 13 The fluorescence emission image is from Example 6;

[0038] Figure 14 This is the result of fitting the fluorescence emission image of Example 6;

[0039] Figure 15 The fluorescence emission image is from Example 7;

[0040] Figure 16 This is the result of fitting the fluorescence emission image of Example 7;

[0041] Figure 17 The fluorescence emission image is from Example 8;

[0042] Figure 18 This is the result of fitting the fluorescence emission image of Example 8;

[0043] Figure 19 The fluorescence emission image is from Example 9;

[0044] Figure 20 This is the result of fitting the fluorescence emission image of Example 9;

[0045] Figure 21 The fluorescence emission image is from Example 10;

[0046] Figure 22 This is a result of fitting the fluorescence emission image of Example 10;

[0047] Figure 23 The fluorescence emission image is from Example 11;

[0048] Figure 24 This is the result of fitting the fluorescence emission image of Example 11;

[0049] Figure 25 The fluorescence emission image is from Example 12;

[0050] Figure 26 This is the result of fitting the fluorescence emission image of Example 12;

[0051] Figure 27 The fluorescence emission image is from Example 13;

[0052] Figure 28 This is the result of fitting the fluorescence emission image of Example 13;

[0053] Figure 29 The fluorescence emission image is from Example 14;

[0054] Figure 30 This is the result of fitting the fluorescence emission image of Example 14;

[0055] Figure 31 The fluorescence emission image is from Example 15;

[0056] Figure 32 This is the result of fitting the fluorescence emission image of Example 15;

[0057] Figure 33 The fluorescence emission image is from Example 16;

[0058] Figure 34 This is the result of fitting the fluorescence emission image of Example 16;

[0059] Figure 35 The fluorescence emission image is from Example 17;

[0060] Figure 36 This is the result of fitting the fluorescence emission image of Example 17;

[0061] Figure 37 The fluorescence emission image is from Example 18;

[0062] Figure 38 This is the result of fitting the fluorescence emission image of Example 18. Detailed Implementation

[0063] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions in the embodiments of this invention will be clearly and completely described below in conjunction with the embodiments of this invention. Obviously, the described embodiments are only some embodiments of this invention, not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0064] This invention provides a method for visually characterizing the accessibility and acid density of solid materials, comprising the following steps:

[0065] 1) The probe molecule solution undergoes an oligomerization reaction in the solid material to be characterized, resulting in a reaction system comprising N reactants, where N≥2; each reactant has a different degree of polymerization.

[0066] 2) Obtain fluorescence emission images of the reaction system;

[0067] 3) Accessibility and acid density were characterized based on fluorescence emission images.

[0068] Specifically, in step 1), the probe molecule solution is mixed with the solid material to be characterized, so that the probe molecules target and recognize the acidic active sites (acid centers) in the solid material. Under the action of the acid centers, the probe molecules undergo oligomerization reaction, and N reactants with different degrees of polymerization are generated according to the spatial position around the acid centers, thereby obtaining a reaction system including N reactants, where N≥2.

[0069] The present invention does not limit the specific selection of solid materials; for example, catalytic cracking catalysts may be selected.

[0070] The oligomerization reaction of the present invention refers to the polymerization reaction of the probe molecules themselves to generate polymers with different degrees of polymerization.

[0071] The N reactants with different degrees of polymerization in this invention refer to at least two reactants with different degrees of polymerization. For example, the reaction system of this invention may include dimers with a degree of polymerization of 2, trimers with a degree of polymerization of 3, tetramers with a degree of polymerization of 4, pentamers with a degree of polymerization of 5, hexamers with a degree of polymerization of 6, etc.

[0072] In step 2), a super-resolution fluorescence microscope is used to detect the fluorescence emission of the reaction system, and then a high-sensitivity camera is used to receive the fluorescence signal of the reactants in the reaction system to obtain a fluorescence emission image of the reaction system.

[0073] This invention does not limit the selection of probe molecules, as long as they can target and recognize acid centers and undergo oligomerization to generate polymers with fluorescent properties.

[0074] This invention does not limit the specific selection of the super-resolution fluorescence microscope, as long as it can emit fluorescence with a specific wavelength.

[0075] This invention does not limit the specific choice of the high-sensitivity camera; for example, a high-sensitivity EMCCD camera (ANDORiXon) can be used.

[0076] In step 3), the obtained fluorescence emission image is processed to obtain the accessibility and acid density of the solid material.

[0077] This invention does not limit the processing method of fluorescence emission images. Two-dimensional Gaussian fitting programs, such as N-Storm, MATLAB, and Python, can be used to process fluorescence emission images. Figure 1This paper describes a two-dimensional Gaussian fitting procedure for processing fluorescence emission images. First, the fluorescence spectral data is preprocessed, such as removing background noise and smoothing. Then, the range of peaks to be fitted by Gaussian is determined by finding the positions of spectral peaks. Subsequently, Gaussian fitting parameters are initialized for each peak, including peak position, peak intensity, and wavelength range. Then, a Gaussian function is used to fit each peak. Finally, the fitting effect is evaluated by comparing the difference between the fitted curve and the original data to determine the accuracy and reliability of the fitting.

[0078] This invention utilizes the targeted recognition of probe molecules with acid centers, enabling the probe molecules to generate polymers of varying degrees of polymerization at the acid centers. Fluorescence is then used to excite the polymers to emit fluorescence signals, obtaining fluorescence emission images. Finally, these images are processed to obtain the accessibility and acid density of the solid-phase material. This invention's visualization method for the accessibility and acid density of solid-phase materials allows for rapid and intuitive location of acid centers using fluorescence emission images, and enables the calculation of accessibility and acid density. Furthermore, the process is simple, requires a small amount of solid-phase material for characterization, causes minimal damage to the solid-phase material, and offers high repeatability.

[0079] In one specific embodiment, accessibility and acid density are characterized based on fluorescence emission images, including: determining the acid density of the solid material to be characterized based on the number of fluorescence emission sites in the fluorescence emission image; and determining the accessibility of the solid material to be characterized based on the number of fluorescence emission sites of each of the N reactants in the fluorescence emission image.

[0080] Specifically, the reactants of this invention are capable of emitting fluorescent signals, and the fluorescent emission sites in the fluorescence emission image represent the distribution locations of the reactants. Since the reactants are polymers formed from probe molecules at acid centers, the fluorescent emission sites can represent the distribution locations of the acid centers, and the number of acid centers can be obtained by calculating the number of fluorescent emission sites. Therefore, the acid density can be obtained by calculating the number of fluorescent emission sites within a certain region.

[0081] The accessibility of this invention is related to the size of the space around the acid center. A larger space around the acid center allows for the generation of reactants with a higher degree of polymerization. The accessibility of the solid material can be determined by the ratio of the number of highly polymerized reactants to the total number of reactants. The reaction system of this invention includes N reactants with different degrees of polymerization. The fluorescence signals of reactants with different degrees of polymerization are distinguished. The number of fluorescence emission sites of reactants with different degrees of polymerization can be calculated using fluorescence emission images. The ratio η of the number of fluorescence emission sites of highly polymerized reactants to the total number of fluorescence emission sites of the reactants is then calculated, which represents the accessibility of the solid material. For example, the reaction system includes a dimer with a degree of polymerization of 2, a trimer with a degree of polymerization of 3, and a tetramer with a degree of polymerization of 4. The number of dimers, trimers, and tetramers is calculated using fluorescence emission images, and then the ratio of the total number of trimers and tetramers to the total number of dimers, trimers, and tetramers is calculated to determine the accessibility of the solid material.

[0082] This invention determines the accessibility and acid density of solid materials by calculating the number of fluorescence emission sites in fluorescence emission images. This method has the advantages of high efficiency, high repeatability, and high accuracy.

[0083] In one specific embodiment, the reaction system includes a dimer with a degree of polymerization of 2 and a trimer with a degree of polymerization of 3. The accessibility of the solid material to be characterized is determined based on the ratio of the number of fluorescence emission sites in the trimer to the total number of fluorescence emission sites in the dimer and trimer. When the reaction system includes both dimer and trimer, the accessibility of the solid material to be characterized can be determined by calculating the ratio of the number of fluorescence emission sites in the trimer to the total number of fluorescence emission sites in the dimer and trimer.

[0084] Due to the structure of the probe molecules themselves and the spatial constraints surrounding the acid centers in solid materials, the reactants obtained from the oligomerization reaction of probe molecules are mostly dimers with a degree of polymerization of 2 and trimers with a degree of polymerization of 3. Therefore, this invention determines the accessibility of the solid material to be characterized by calculating the ratio of the number of fluorescence emission sites in the trimers to the total number of fluorescence emission sites in the dimers and trimers. This method can improve the efficiency and feasibility of visual characterization of solid materials, and the obtained accessibility and acid density can meet the accuracy requirements of testing in industrial production, laying the foundation for the widespread application of visual characterization.

[0085] In one specific embodiment, acquiring a fluorescence emission image of the reaction system includes: emitting excitable light into the reaction system according to the fluorescence excitation wavelengths of the N reactants to acquire fluorescence emission images of M reactants, where M≥2; and performing composite processing on the fluorescence emission images of the M reactants to obtain a fluorescence emission image of the reaction system.

[0086] Based on the different fluorescence excitation wavelengths required for reactants with different degrees of polymerization and the different fluorescence signals emitted, this invention selects corresponding fluorescence excitation wavelengths to excite the reactants. N reactants with different degrees of polymerization will emit different fluorescence signals. Therefore, a corresponding scanning wavelength is set in a high-sensitivity camera to receive the corresponding fluorescence signals. Simultaneously, the scanning frequency and number of scans of the high-sensitivity camera are controlled to obtain M fluorescence emission images. Each fluorescence emission image simultaneously includes the fluorescence signals of reactants with different degrees of polymerization. These M fluorescence emission images are then superimposed to form a single fluorescence emission image, which is the fluorescence emission image of the reaction system. This fluorescence emission image of the reaction system includes fluorescence emission images from all different scan times. Figure 2 This is a composite processing method for fluorescence emission images, which involves overlapping multiple localization data points obtained by Gaussian fitting to synthesize the final fluorescence emission image.

[0087] This invention does not limit the scanning frequency and number of scans of the high-sensitivity camera, and can be selected according to actual needs. For example, the scanning frequency can be selected as 100ms laser exposure time, and the number of scans can be selected as 1000 cumulative image frames.

[0088] When this method is used to obtain fluorescence emission images of the reaction system, the fluorescence emission signals of all reactants can be obtained, avoiding the omission of fluorescence emission signals that would result in a smaller number of acid centers being measured, thus leading to inaccuracies in accessibility and acid density.

[0089] In one specific embodiment, the probe molecule is selected from at least one of p-methoxystyrene, furfuryl alcohol, and thiophene; and / or, the solvent is selected from at least one of n-pentane, ethanol, and n-octane. When the probe molecule is selected from the above compounds, it can target and recognize the acid center and undergo oligomerization at the acid center to generate a polymer with fluorescent properties, thereby ensuring the accessibility of the solid material and the feasibility of visual characterization of acid density. Preferably, the probe molecule is p-methoxystyrene. The emission wavelengths of the fluorescence signals of the dimer and trimer of p-methoxystyrene are significantly different, which facilitates the analysis of the fluorescence signal and is beneficial to the accessibility of the solid material and the accurate characterization of the acid center.

[0090] When the probe molecule is p-methoxystyrene, n-pentane is chosen as the solvent to obtain a probe molecule solution; when the probe molecule is furfuryl alcohol, anhydrous ethanol is chosen as the solvent; and when the probe molecule is thiophene, n-octane is chosen as the solvent. Choosing different solvents for different probe molecules allows for the preparation of highly stable probe molecule solutions, which facilitates the entry of probe molecules into the solid-phase material, thereby achieving the oligomerization reaction of probe molecules at the acid center. This ensures the accessibility of the solid-phase material and the feasibility of visual characterization of acid density.

[0091] In one specific embodiment, the molar concentration of the probe molecule solution is 1 × 10⁻⁶. -10 -1×10 -3 mol / L, for example, 1×10 -10 mol / L, 1×10 -9 mol / L, 1×10 -8 mol / L, 1×10 -7 mol / L, 1×10 -6 mol / L, 1×10 -5 mol / L, 1×10 -4 mol / L or 1×10 -3 The molar concentration of the probe molecule solution is within the above range, which facilitates molecular diffusion of the probe molecules within the solid-phase material. This allows for greater targeting of the acid centers by the probe molecules, enabling them to aggregate at the acid centers and ensuring the feasibility of visual characterization. Preferably, the molar concentration of the probe molecule solution is 1 × 10⁻⁶ mol / L. -6 mol / L.

[0092] In one specific embodiment, the solid-phase material is an FCC catalyst, which includes one of ZSM molecular sieves and Y-type molecular sieves. The visualization characterization method for the accessibility and acid density of the solid-phase material provided by this invention can rapidly characterize FCC catalysts, quickly screen FCC catalysts that meet the target requirements, and is simple to operate with high repeatability. When the FCC catalyst is one of the above-mentioned catalysts, the accessibility and acid density determined by the visualization characterization method provided by this invention have high accuracy.

[0093] In one specific embodiment, the mass ratio of the probe molecule solution to the solid material is 0.0001-0.01, for example, 0.0001, 0.0002, 0.0003, 0.0004, 0.0005, 0.0006, 0.0007, 0.0008, 0.0009, 0.001, 0.002, 0.003, 0.004, 0.005, 0.006, 0.007, 0.008, 0.009, or 0.01. When the mass ratio of the probe molecule solution to the solid material is within the above range, it ensures that the probe molecules can target and identify all acid centers within the solid material, and that the probe molecules can undergo sufficient oligomerization at the acid centers within the solid material. This ensures the accessibility and accuracy of the measured acid density, while also avoiding the waste of probe molecules and reducing costs.

[0094] In one specific embodiment, before the probe molecule solution undergoes an oligomerization reaction in the solid material to be characterized, the method further includes calcining the solid material at an ambient temperature of not less than 500°C for 4-8 hours. This invention also includes an activation step for the solid material before the probe molecules react with it. Specifically, the solid material is placed in a muffle furnace for calcination in an air atmosphere at an ambient temperature of not less than 500°C, such as 500°C, 550°C, 600°C, 650°C, or 700°C, for 4-8 hours, such as 4 hours, 5 hours, 6 hours, 7 hours, or 8 hours. This activation step removes moisture and impurities from the solid material, allowing the probe molecule solution to diffuse within it. This enables the probe molecules to target and recognize acid centers and avoids the influence of impurities and moisture on the oligomerization reaction, thereby ensuring the accessibility and accuracy of the measured acid density.

[0095] In one specific embodiment, the oligomerization reaction time is 30-90 min, such as 30 min, 40 min, 50 min, 60 min, 70 min, 80 min, or 90 min. When the reaction time of the probe molecule oligomerization reaction is within the above range, the probe molecule can undergo sufficient oligomerization reaction to generate the final reactant, avoiding the interruption of the oligomerization reaction due to excessively short reaction time, which would reduce the amount of highly polymerized reactants, or even prevent the probe molecules from polymerizing, leading to a decrease in accessibility and the accuracy of acid density.

[0096] The present invention will be further described in detail below through specific embodiments.

[0097] Example 1

[0098] The visualization characterization of the acid centers of the catalyst in this embodiment includes the following steps:

[0099] 1. The HZSM-5 molecular sieve with a silicon-to-aluminum ratio of 30 to be tested was placed in a muffle furnace for calcination and activation. It was kept at 550℃ for 6 hours and then cooled to room temperature in an environment with humidity less than 10% for later use.

[0100] 2. Weigh 1 mg of activated HZSM-5 molecular sieve and sprinkle it evenly in the center of the bottom of a laser confocal glass culture dish, then add 2 mL of n-pentane solution;

[0101] 3. Add 10 μL of 7.4 × 10⁻⁶ solution to the petri dish. -6 A mol / L p-methoxystyrene solution was reacted for 60 min.

[0102] 4. The super-resolution fluorescence microscope parameters were set as follows: excitation light was focused through a 100× oil immersion objective (1.4NA); excitation wavelengths of 488nm were selected for the dimer, and 561nm for the trimer; the laser exposure time was set to 100ms. The fluorescence emitted by the dimer and trimer was detected using a high-sensitivity electron multiplication charge-coupled device (EMCCD) camera (ANDORiXon3), with a cumulative image frame count of 1000 frames. Fluorescence emission images are shown below. Figure 3 The detected fluorescence emission images were processed using a two-dimensional Gaussian fitting program. The processed results are shown below. Figure 4 .

[0103] Figure 4 In the diagram, pink dots represent trimers, and blue dots represent dimers. The location of acid centers in the catalyst can be visually observed through the distribution of these dots. The number of pink dots (A) is 187, and the number of blue dots (B) is 140. The ratio of pink dots to the total number of dots (η) is 57.2%. Therefore, the accessibility of acid centers in HZSM-5 molecular sieve with a silica-to-alumina ratio of 30 is 57.2%.

[0104] The acid density of the acid centers in the catalyst can be calculated as 1*1-84*84μm. 2 The number of points within the region is obtained, therefore, the acid density of the acid centers of the HZSM-5 molecular sieve with a silica-alumina ratio of 30 is 372.

[0105] Example 2

[0106] The visualization characterization of the acid centers of the catalyst in this embodiment is largely the same as that in Example 1. The difference is that the solid material to be measured is HZSM-5 molecular sieve with a silicon-to-aluminum ratio of 100.

[0107] Fluorescence emission images are shown Figure 5 The detected fluorescence emission images were processed using a two-dimensional Gaussian fitting program. The processed results are shown below. Figure 6 .

[0108] A is 618, B is 177, and η is 77.7%. Therefore, the accessibility of the acid centers of the HZSM-5 molecular sieve with a silica-to-alumina ratio of 100 is 77.7%. The acid density of the acid centers of the HZSM-5 molecular sieve with a silica-to-alumina ratio of 100 is 795.

[0109] Example 3

[0110] The visualization characterization of the acid centers of the catalyst in this embodiment is largely the same as that in Example 1. The difference is that the solid material to be measured is HZSM-5 molecular sieve with a silicon-to-aluminum ratio of 470.

[0111] Fluorescence emission images are shown Figure 7The detected fluorescence emission images were processed using a two-dimensional Gaussian fitting program. The processed results are shown below. Figure 8 .

[0112] A is 1379, B is 278, and η is 83.2%. Therefore, the accessibility of the acid centers of the HZSM-5 molecular sieve with a silica-to-alumina ratio of 470 is 83.2%. The acid density of the acid centers of the HZSM-5 molecular sieve with a silica-to-alumina ratio of 470 is 1657.

[0113] Example 4

[0114] The visualization characterization of the acid centers of the catalyst in this embodiment is largely the same as that in Example 1, except that the solid material to be measured is an FCC catalyst treated with a solution at pH 7.

[0115] Fluorescence emission images are shown Figure 9 The detected fluorescence emission images were processed using a two-dimensional Gaussian fitting program. The processed results are shown below. Figure 10 .

[0116] A is 130, B is 60, and η is 68.4%. Therefore, the accessibility of the acid sites of the FCC catalyst treated with a solution at pH 7 is 68.4%. The acid density of the acid sites of the FCC catalyst treated with a solution at pH 7 is 190.

[0117] Example 5

[0118] The visualization characterization of the acid centers of the catalyst in this embodiment is largely the same as that in Example 1, except that the solid material to be measured is an FCC catalyst treated with a solution at pH 6.

[0119] Fluorescence emission images are shown Figure 11 The detected fluorescence emission images were processed using a two-dimensional Gaussian fitting program. The processed results are shown below. Figure 12 .

[0120] A is 615, B is 123, and η is 83.3%. Therefore, the accessibility of the acid sites of the FCC catalyst treated with a solution at pH 6 is 83.3%. The acid density of the acid sites of the FCC catalyst treated with a solution at pH 6 is 738.

[0121] Example 6

[0122] The visualization characterization of the acid centers of the catalyst in this embodiment is largely the same as that in Example 1, except that the solid material to be measured is an FCC catalyst treated with a solution at pH 5.

[0123] Fluorescence emission images are shown Figure 13The detected fluorescence emission images were processed using a two-dimensional Gaussian fitting program. The processed results are shown below. Figure 14 .

[0124] A is 167, B is 197, and η is 84.8%. Therefore, the accessibility of the acid sites of the FCC catalyst treated with a solution at pH 5 is 84.8%. The acid density of the acid sites of the FCC catalyst treated with a solution at pH 5 is 197.

[0125] Example 7

[0126] The visualization characterization of the acid centers of the catalyst in this embodiment is largely the same as that in Example 1, except that the solid material to be measured is an FCC catalyst treated with a solution at pH 4.

[0127] Fluorescence emission images are shown Figure 15 The detected fluorescence emission images were processed using a two-dimensional Gaussian fitting program. The processed results are shown below. Figure 16 .

[0128] A is 144, B is 31, and η is 82.3%. Therefore, the accessibility of the acid sites of the FCC catalyst treated with a solution at pH 4 is 82.3%. The acid density of the acid sites of the FCC catalyst treated with a solution at pH 4 is 175.

[0129] Example 8

[0130] The visualization characterization of the acid centers of the catalyst in this embodiment is largely the same as that in Example 1, except that the solid material to be measured is an FCC catalyst with a crystallization time of 0.

[0131] Fluorescence emission images are shown Figure 17 The detected fluorescence emission images were processed using a two-dimensional Gaussian fitting program. The processed results are shown below. Figure 18 .

[0132] A is 115, B is 104, and η is 52.5%. Therefore, the accessibility of the acid center of the FCC catalyst with a crystallization time of 0 is 52.5%. The acid density of the acid center of the FCC catalyst with a crystallization time of 0 is 219.

[0133] Example 9

[0134] The visualization characterization of the acid centers of the catalyst in this embodiment is largely the same as that in Example 1. The difference is that the solid material to be measured is an FCC catalyst with a crystallization time of 12 hours.

[0135] Fluorescence emission images are shown Figure 19 The detected fluorescence emission images were processed using a two-dimensional Gaussian fitting program. The processed results are shown below. Figure 20 .

[0136] A is 512, B is 216, and η is 70.3%. Therefore, the accessibility of the acid sites in the FCC catalyst with a crystallization time of 12 h is 70.3%. The acid density of the acid sites in the FCC catalyst with a crystallization time of 12 h is 728.

[0137] Example 10

[0138] The visualization characterization of the acid centers of the catalyst in this embodiment is largely the same as that in Example 1. The difference is that the solid material to be measured is an FCC catalyst with a crystallization time of 16 hours.

[0139] Fluorescence emission images are shown Figure 21 The detected fluorescence emission images were processed using a two-dimensional Gaussian fitting program. The processed results are shown below. Figure 22 .

[0140] A is 173, B is 149, and η is 53.7%. Therefore, the accessibility of the acid sites in the FCC catalyst with a crystallization time of 16 h is 53.7%. The acid density of the acid sites in the FCC catalyst with a crystallization time of 16 h is 322.

[0141] Example 11

[0142] The visualization characterization of the acid centers of the catalyst in this embodiment is largely the same as that in Example 1, except that the solid material to be measured is an FCC catalyst.

[0143] Fluorescence emission images are shown Figure 23 The detected fluorescence emission images were processed using a two-dimensional Gaussian fitting program. The processed results are shown below. Figure 24 .

[0144] A is 134, B is 192, and η is 41.1%. Therefore, the accessibility of the acid center of the FCC catalyst is 41.1%. The acid density of the acid center of the FCC catalyst is 326.

[0145] Example 12

[0146] The visualization characterization of the acid centers of the catalyst in this embodiment is largely the same as that in Example 1, except that the solid material to be measured is an FCC catalyst.

[0147] Fluorescence emission images are shown Figure 25 The detected fluorescence emission images were processed using a two-dimensional Gaussian fitting program. The processed results are shown below. Figure 26 .

[0148] A is 48, B is 88, and η is 35.3%. Therefore, the accessibility of the acid center of the FCC catalyst is 35.3%. The acid density of the acid center of the FCC catalyst is 136.

[0149] Example 13

[0150] The visualization characterization of the acid centers of the catalyst in this embodiment is largely the same as in Example 1, except that the solid material to be measured is an FCC catalyst. The matrix structure of this FCC catalyst is kaolin + 10% novel macroporous alumina matrix.

[0151] Fluorescence emission images are shown Figure 27 The detected fluorescence emission images were processed using a two-dimensional Gaussian fitting program. The processed results are shown below. Figure 28 .

[0152] A is 339, B is 187, and η is 64.4%. Therefore, the accessibility of the acid center of the FCC catalyst is 64.4%. The acid density of the acid center of the FCC catalyst is 526.

[0153] Example 14

[0154] The visualization characterization of the acid centers of the catalyst in this embodiment is largely the same as in Example 1, except that the solid material to be measured is an FCC catalyst. The matrix structure of this FCC catalyst is kaolin + 25% novel macroporous alumina matrix.

[0155] Fluorescence emission images are shown Figure 29 The detected fluorescence emission images were processed using a two-dimensional Gaussian fitting program. The processed results are shown below. Figure 30 .

[0156] A is 1300, B is 421, and η is 75.5%. The accessibility of the acid center of the FCC catalyst is 75.5%. The acid density of the acid center of the FCC catalyst is 1721.

[0157] Example 15

[0158] The visualization characterization of the acid centers of the catalyst in this embodiment is largely the same as in Example 1, except that the solid material to be measured is an FCC catalyst. The matrix structure of this FCC catalyst is kaolin + 25% boehmite.

[0159] Fluorescence emission images are shown Figure 31 The detected fluorescence emission images were processed using a two-dimensional Gaussian fitting program. The processed results are shown below. Figure 32 .

[0160] A is 236, B is 249, and η is 48.7%. Therefore, the accessibility of the acid center of the FCC catalyst is 48.7%. The acid density of the acid center of the FCC catalyst is 485.

[0161] Example 16

[0162] The visualization characterization of the acid centers of the catalyst in this embodiment includes the following steps:

[0163] 1. The HZSM-5 molecular sieve with a silicon-to-aluminum ratio of 30 to be tested was placed in a muffle furnace for calcination and activation. It was kept at 550℃ for 6 hours and then cooled to room temperature in an environment with humidity less than 10% for later use.

[0164] 2. Weigh 1 mg of activated HZSM-5 molecular sieve and sprinkle it evenly in the center of the bottom of a laser confocal glass culture dish, then add 2 mL of anhydrous ethanol;

[0165] 3. Add 10 μL of 7.4 × 10⁻⁶ solution to the petri dish. -6 A furfuryl alcohol solution of mol / L was reacted for 60 min.

[0166] 4. The super-resolution fluorescence microscope parameters were set as follows: excitation light was focused through a 100× oil immersion objective (1.4NA); excitation wavelengths of 488nm were selected for the dimer, and 561nm for the trimer; the laser exposure time was set to 100ms. The fluorescence emitted by the dimer and trimer was detected using a high-sensitivity electron multiplication charge-coupled device (EMCCD) camera (ANDORiXon3), with a cumulative image frame count of 1000 frames. Fluorescence emission images are shown below. Figure 33 The detected fluorescence emission images were processed using a two-dimensional Gaussian fitting program. The processed results are shown below. Figure 34 .

[0167] A is 214, B is 185, and η is 53.6%. Therefore, the accessibility of the acid centers of HZSM-5 molecular sieve is 53.6%. The acid density of the acid centers of HZSM-5 molecular sieve is 399.

[0168] Example 17

[0169] The visualization characterization of the acid centers of the catalyst in this embodiment is largely the same as that in Example 16, except that the silica-alumina ratio of the HZSM-5 molecular sieve used is 100.

[0170] Fluorescence emission images are shown Figure 35 The detected fluorescence emission images were processed using a two-dimensional Gaussian fitting program. The processed results are shown below. Figure 36 .

[0171] A is 131, B is 138, and η is 45.3%. Therefore, the accessibility of the acid centers of HZSM-5 molecular sieve is 45.3%. The acid density of the acid centers of HZSM-5 molecular sieve is 289.

[0172] Example 18

[0173] The visualization characterization of the acid centers of the catalyst in this embodiment is largely the same as that in Example 16, except that the silica-alumina ratio of the HZSM-5 molecular sieve used is 470.

[0174] Fluorescence emission images are shown Figure 37 The detected fluorescence emission images were processed using a two-dimensional Gaussian fitting program. The processed results are shown below. Figure 38 .

[0175] A is 120, B is 124, and η is 49.2%. Therefore, the accessibility of the acid centers of HZSM-5 molecular sieve is 49.2%. The acid density of the acid centers of HZSM-5 molecular sieve is 244.

[0176] In summary, the visual characterization of accessibility and acid centers in solid materials provided by this invention enables the location of acid centers within solid materials and allows for quantitative analysis of accessibility and acid density. Furthermore, the visual characterization method provided by this invention offers advantages such as using less solid material, causing minimal damage to the solid material, speed, good repeatability, and simple process.

[0177] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for visually characterizing the accessibility and acid density of a solid material, characterized in that, Includes the following steps: 1) The probe molecule solution is subjected to oligomerization in the solid material to be characterized to obtain a reaction system comprising N reactants, where N≥2; each reactant has a different degree of polymerization. 2) Obtain fluorescence emission images of the reaction system; 3) The accessibility and acid density are characterized based on the fluorescence emission image.

2. The method for visually characterizing the accessibility and acid density of solid materials according to claim 1, characterized in that, The characterization of accessibility and acid density based on the fluorescence emission image includes: The acid density of the solid material to be characterized is determined based on the number of fluorescence emission sites in the fluorescence emission image. The accessibility of the solid material to be characterized is determined based on the number of fluorescence emission sites of each of the N reactants in the fluorescence emission image.

3. The method for visually characterizing the accessibility and acid density of solid materials according to claim 2, characterized in that, The reaction system includes a dimer with a degree of polymerization of 2 and a trimer with a degree of polymerization of 3; The accessibility of the solid material to be characterized is determined by the ratio of the number of fluorescence emission sites in the trimer to the total number of fluorescence emission sites in the dimer and trimer.

4. The method for visually characterizing the accessibility and acid density of solid materials according to claim 3, characterized in that, The acquisition of fluorescence emission images of the reaction system includes: Based on the fluorescence excitation wavelengths of the N reactants, excitable light is emitted from the reaction system to obtain M fluorescence emission images of the reactants, where M≥2; The fluorescence emission images of the M reactants are combined to obtain the fluorescence emission image of the reaction system.

5. The method for visually characterizing the accessibility and acid density of solid materials according to claim 4, characterized in that, The probe molecule is selected from at least one of p-methoxystyrene, furfuryl alcohol, and thiophene; and / or, the solvent is selected from at least one of n-pentane, ethanol, and n-octane.

6. The method for visually characterizing the accessibility and acid density of solid materials according to claim 5, characterized in that, The molar concentration of the probe molecule solution is 1×10⁻⁶. -10 -1×10 -3 mol / L.

7. The method for visually characterizing the accessibility and acid density of solid materials according to claim 6, characterized in that, The solid material is an FCC catalyst, which includes one of HZSM-5 molecular sieve and SAPO-5 molecular sieve.

8. The method for visually characterizing the accessibility and acid density of solid materials according to claim 7, characterized in that, The mass ratio of the probe molecule solution to the solid material is 0.0001-0.

01.

9. The method for visually characterizing the accessibility and acid density of solid materials according to claim 8, characterized in that, Before the probe molecule solution undergoes an oligomerization reaction in the solid material to be characterized, the method further includes: calcining the solid material to be characterized at an ambient temperature of not less than 500°C for 4-8 hours.

10. The method for visually characterizing the accessibility and acid density of solid materials according to claim 9, characterized in that, The reaction time for the oligomerization reaction is 30-90 min.

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