Silica-alumina microspheres, methods of making and using the same

Abstract

The present application relates to the field of material synthesis, discloses a silicon-aluminum microsphere and a preparation method and application thereof. The silicon-aluminum microsphere has high sphericity, a width-height ratio (b / l) of 0.90 or more, and a sphericity index of 88 or more, which is conducive to improving the fluidization performance of the microsphere in a fluidized bed reactor and other devices. The silicon-aluminum microsphere has high strength, with a straight pipe wear coefficient of 0.3-2 wt% / h, indicating that the microsphere has good wear resistance and is conducive to improving the service life of related products. The silicon-aluminum microsphere has a narrow particle size distribution range, with a D90 / D10 ratio of 2.8 or less, which is conducive to ensuring the consistency of product performance and is suitable for industrial fluidized bed process conditions. The silicon-aluminum microsphere is rich in mesopores, with a mesopore specific surface area of 40-65 m 2 / g and a mesopore volume of 0.08-0.12 cm 3 / g, and the rich pore structure is conducive to improving the mass transfer performance of reactants in the microsphere and facilitating subsequent in-situ crystallization and other chemical reactions of the microsphere.

Description

Technical Field

[0001] This invention relates to the field of materials synthesis, specifically to a silicon-aluminum microsphere, a method for preparing the silicon-aluminum microsphere, the silicon-aluminum microsphere obtained by the method, and the application of the silicon-aluminum microsphere in the preparation of microsphere catalysts. Background Technology

[0002] Microsphere catalysts, prepared from micron-sized spherical silica-alumina materials, are an important class of industrial refining and chemical catalysts. For example, the widely used fluidized bed catalytic cracking (FCC) units utilize microsphere catalysts (with an average particle size of approximately 70 micrometers) to meet the actual operational requirements of the unit. In industrial applications, the strength and sphericity of microsphere catalysts significantly impact their performance (activity and lifetime). Inadequate strength or sphericity will exacerbate wear between catalyst microspheres, increase the amount of fine powder inside the unit, cause excessive pressure drop, affect the overall fluidization state of the catalyst and the catalyst-reactant contact, and even create safety hazards. Typically, microsphere catalysts are obtained through spray drying, where a specific composition of spray precursor liquid is prepared, and the droplets are rapidly dried under the action of a high-temperature airflow in a spray tower to form solid microspheres. The particle size, chemical composition, and preparation method of the solid particles in the spray precursor liquid have a significant impact on the strength, sphericity, and chemical composition of the spray-formed microspheres.

[0003] Currently, besides the semi-synthetic route of directly mixing active components (such as molecular sieves and metal oxides) with matrix materials (such as clay and alumina) and then preparing microsphere catalysts through spray drying, another important technical route for preparing catalytic materials is to directly introduce active components through in-situ growth from silicon-aluminum microsphere materials. In this type of route, obtaining silicon-aluminum microsphere precursors with high sphericity and high strength is the key and technical challenge for achieving the subsequent in-situ preparation of catalytic materials. Existing patents have used natural mineral clay as raw material to prepare microsphere catalytic materials through in-situ crystallization. For example, CN101537368A discloses a method for preparing an in-situ crystallized catalytic cracking catalyst. This method uses kaolin as raw material, which is spray-formed and calcined to prepare microspheres for subsequent crystallization reactions. The final product has a silicon-aluminum ratio of 3.5 to 5.5. After exchanging and calcining, the desired catalyst is obtained from this crystallized product. Using silicon-aluminum structural unit components as partial silicon, aluminum, and sodium sources in the synthesis enables the preparation of in-situ crystallized molecular sieves in a shorter time, thereby shortening the process, increasing yield, and reducing production costs. CN101462740B discloses a method for in-situ crystallization preparation of ZSM-5 zeolite. This method uses spray-dried kaolin microspheres and silica-rich clay microspheres as mixed reactants for in-situ hydrothermal crystallization to obtain crystallized products. However, this method requires subsequent alkali-mixed calcination and acid extraction of the microspheres to further increase the silicon-aluminum ratio and thus increase the ZSM-5 molecular sieve content in the crystallized products. CN104276585B discloses a method for in-situ crystallization synthesis of NaY molecular sieves from composite clay microspheres. This method prepares mixed clay calcined microspheres and calcined microspheres containing molecular sieves, respectively, and crystallizes them with an external silicon source (sodium silicate) to prepare a mesoporous catalytic composite material containing NaY zeolite molecular sieves. Although the aforementioned patents prepared silica-alumina microspheres for crystallization using natural minerals as raw materials, the obtained microspheres all required high-temperature (600-1100℃) calcination for activation / strengthening, and the preparation process did not focus on controlling the strength and sphericity of the microspheres. Li et al. used mesoporous materials (SBA-15), TEOS, and aluminum nitrate as raw materials to prepare high-sphericity solid silica-alumina microsphere catalysts by spray drying (ACS Appl. Mater. Interfaces 2020, 12, 19, 21922–21935), but the active components of the microsphere materials obtained in this work were limited, and it was not suitable for obtaining other active components through in-situ crystallization, thus limiting its applicability.

[0004] Therefore, in the preparation of microsphere materials using natural mineral soil as raw material, obtaining high sphericity and high strength silicon-aluminum microsphere materials by changing the raw materials and preparation methods, while increasing the content of active silicon-aluminum components and reducing the energy consumption required in the microsphere calcination / activation process, is an important direction for developing a green synthesis route for high-quality microsphere catalytic materials. Summary of the Invention

[0005] The purpose of this invention is to overcome the problems existing in the prior art and provide a silicon-aluminum microsphere and its preparation method. The silicon-aluminum microsphere has the advantages of being rich in mesopores, having a narrow particle size distribution range, high sphericity and high strength. Moreover, the preparation method is simple, low in cost, and conducive to the subsequent crystallization process.

[0006] To achieve the above objectives, the first aspect of the present invention provides a silicon-aluminum microsphere, wherein the aspect ratio (b / l) of the microsphere is 0.9 or more and the sphericity index (Q) is 88 or more;

[0007] The ratio of D90 to D10 of the microspheres is less than 2.8;

[0008] The wear coefficient of the silicon-aluminum microspheres in the straight tube is 0.3-2 wt% / h;

[0009] The silicon-aluminum microspheres contain mesopores with a specific surface area of ​​40-65 m². 2 / g, mesopore volume is 0.08-0.12cm³ 3 / g.

[0010] The second aspect of the present invention provides a method for preparing silicon-aluminum microspheres, the method comprising: mixing amorphous silicon-based raw materials, clay, a first binder and water to obtain a mixed clay slurry;

[0011] The mixed soil slurry is mixed with the second binder to obtain a spray precursor liquid;

[0012] The spray precursor liquid was spray-dried and calcined to obtain silicon-aluminum microspheres;

[0013] The viscosity of the first adhesive is lower than that of the second adhesive;

[0014] The silicon-aluminum ratio in the amorphous silicon-based raw material is 10 or higher.

[0015] Preferably, the silicon-to-aluminum ratio in the amorphous silicon-based raw material is 20 or higher; and / or

[0016] The clay is selected from at least one of kaolin, illite, and bentonite; and / or

[0017] The viscosity (25°C) of the first adhesive is 3-15 mPa·s; and / or

[0018] The viscosity (25°C) of the second adhesive is 15-30 mPa·s; and / or

[0019] The first adhesive and the second adhesive are each independently selected from at least one of aluminum sol, silica sol, and water glass.

[0020] The third aspect of the present invention provides silicon-aluminum microspheres prepared by the method described above.

[0021] The fourth aspect of the present invention provides the use of the microspheres described above in the preparation of microsphere catalysts.

[0022] The silicon-aluminum microspheres prepared by the present invention using the above technical solution have the following beneficial effects:

[0023] (1) The silicon-aluminum microspheres obtained by the present invention have high sphericity, an aspect ratio (b / l) of 0.9 or higher, and a sphericity index of 88 or higher, which is beneficial to improving their fluidization performance in fluidized bed reactors and other devices;

[0024] (2) The silicon-aluminum microspheres obtained by the present invention have high strength and a straight tube wear coefficient of 0.3-2wt% / h, indicating that they have good wear resistance and are beneficial to improving the service life of related products;

[0025] (3) The silicon-aluminum microspheres obtained by the present invention have a narrow particle size distribution range, and the ratio of D90 to D10 of the microspheres is less than 2.8, which is beneficial to ensure the consistency of product performance and is also suitable for industrial fluidized bed process conditions.

[0026] (4) The silicon-aluminum microspheres obtained in this invention are rich in mesopores, with a mesopore specific surface area of ​​40-65 m². 2 / g, mesopore volume is 0.08-0.12cm³ 3 / g, the abundant porous structure is beneficial to improving the mass transfer performance of reactants within it, and is conducive to subsequent chemical reactions such as in-situ crystallization of microspheres.

[0027] Moreover, the method described in this invention is simple to operate, low in cost, and suitable for industrial production. Attached Figure Description

[0028] Figure 1 To obtain a scanning electron microscope (SEM) image of the product magnified 500 times for Example 1.

[0029] Figure 2 To obtain a scanning electron microscope (SEM) image of the product magnified 400 times for Comparative Example 1.

[0030] Figure 3 To obtain a scanning electron microscope (SEM) image of the product magnified 400 times for Comparative Example 2.

[0031] Figure 4 This shows the particle length as a parameter in the quantitative test of sphericity, referring to the maximum Feret radius (X). Feret,max The definition of ).

[0032] Figure 5 This illustrates the quantitative test of sphericity for X. cDefinition. Detailed Implementation

[0033] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0034] The first aspect of the present invention provides a silicon-aluminum microsphere, wherein the aspect ratio (b / l) of the microsphere is 0.9 or more and the sphericity index (Q) is 88 or more;

[0035] The ratio of D90 to D10 of the microspheres is less than 2.8;

[0036] The wear coefficient of the silicon-aluminum microspheres in the straight tube is 0.3-2 wt% / h;

[0037] The silicon-aluminum microspheres contain mesopores with a specific surface area of ​​40-65 m². 2 / g, mesopore volume is 0.08-0.12cm³ 3 / g.

[0038] It should be understood that in porous materials, pores with a diameter less than 2 nm are called micropores, and pores with a diameter between 2-50 nm are called mesopores.

[0039] like Figure 1 As shown, the surface of the silicon-aluminum microspheres is basically smooth, and the overall shape is basically spherical. Preferably, the aspect ratio of the microspheres is 0.95 or higher, such as 0.95, 0.96, 0.97, 0.98, 0.99, or any range between any two values, and the sphericity index (Q) is 93 or higher, such as 93, 94, 95, 96, 97, 98, 99, or any range between any two values.

[0040] The aspect ratio (b / l) is the ratio of the particle's width to its length, and the sphericity index (Q) is b / l ≥ 0.9, meaning Q represents the percentage of particles that satisfy b / l ≥ 0.9. Both are quantitative tests of sphericity, performed using an image particle analyzer.

[0041] The ratio of D90 to D10 of the microspheres is less than 2.8 (for example, 1.5, 2, 2.2, 2.4, 2.6, 2.8, and any range between any two values), preferably 2-2.4.

[0042] In this invention, D90 refers to the particle size corresponding to 90% of the cumulative particle size distribution of a sample, meaning that 90% of the particles are smaller than D90; D50 refers to the particle size corresponding to 50% of the cumulative particle size distribution of a sample, meaning that 50% of the particles are smaller than D50, i.e., the average particle size; D10 refers to the particle size corresponding to 10% of the cumulative particle size distribution of a sample, meaning that 10% of the particles are smaller than D10. Testing is conducted according to NB / SH / T 0951-2017, and the testing instrument can be a Malvern Mastersizer 2000.

[0043] The size of the microspheres can vary depending on their application. For example, when the microspheres are used to prepare FCC catalysts, the average particle size D50 of the microspheres is preferably 60-80 μm, such as 60, 65, 70, 75, 80 μm, or any range between any two values.

[0044] Preferably, the straight tube wear coefficient of the silicon-aluminum microspheres is 0.3-1.2wt% / h, for example, 0.3, 0.5, 0.7, 0.9, 1, 1.2wt% / h and any range between any two values.

[0045] The straight pipe wear index was tested according to the "Determination of Wear Index of Catalytic Cracking Catalyst - Straight Pipe Method (NB / SH / T 0964-2017)".

[0046] Preferably, the bulk density of the silicon-aluminum microspheres is 0.6-0.9. The bulk density is tested according to the standard test methods for the mechanical quantitative bulk density of catalysts and catalyst supports formed according to ASTM D4164-03(2008) and ASTM D 6135-2003.

[0047] Preferably, the microspheres contain 40-97 wt% silicon dioxide (e.g., 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 97 wt% and any range between any two values) and 3-60 wt% aluminum oxide (e.g., 3, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60 wt% and any range between any two values).

[0048] Preferably, the silicon-aluminum microspheres have a silicon-to-aluminum ratio of 1 or higher, such as 1, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50 or higher, or any range between any two values.

[0049] The silicon-to-aluminum ratio is the molar ratio of SiO2 to Al2O3. The relative amounts of SiO2 and Al2O3 were quantitatively characterized using X-ray fluorescence spectrometry. Experimental instrument: Rigaku Electric Industries, Ltd., Japan, X-ray fluorescence spectrometer 3271E. Experimental conditions: Powder samples were pressed into tablets, a rhodium target was used, the excitation voltage was 50 kV, and the excitation current was 50 mA. The intensity of each element's spectral line was detected using a scintillation counter and a proportional counter. Quantitative and semi-quantitative analysis of elemental content was performed using the external standard method.

[0050] Preferably, the BET specific surface area of ​​the microspheres is 40-70 m². 2 / g, for example, 40, 45, 50, 55, 60, 65, 70m 2 The total pore volume is 0.08-0.12 cm³, and the total pore volume is within any range of g and any two values. 3 / g, for example, 0.08, 0.09, 0.1, 0.11, 0.12cm 3 / g and any range between any two values.

[0051] Preferably, the micropore specific surface area of ​​the microspheres is 0.5-3 m². 2 / g, micropore volume 0.001-0.01cm³ 3 / g.

[0052] The mesoporous surface area, specific surface area, pore volume (total pore volume), and pore size distribution were measured using the low-temperature nitrogen adsorption capacity method. Experimental instrument: Micromeritics ASAP2400 static nitrogen adsorption instrument. Experimental conditions: The sample was degassed under vacuum at 1.33 Pa and 300 °C for 4 h, then contacted with liquid nitrogen at 77 K for isothermal adsorption / desorption. Adsorption / desorption isotherms were measured, and the specific surface area and pore volume were calculated using the BET formula.

[0053] Preferably, the water droplet pore volume of the silicon-aluminum microspheres is 0.2-0.4 mL / g, more preferably 0.25-0.35 mL / g.

[0054] The water pore volume was tested according to the ASTM standard "Standard Guide for Determination of Pore Volume of Powdered Catalysts and Catalyst Carriers by Water Adsorption" (D8393-21).

[0055] The second aspect of the present invention provides a method for preparing silicon-aluminum microspheres, the method comprising: mixing amorphous silicon-based raw materials, clay, a first binder and water to obtain a mixed clay slurry;

[0056] The mixed soil slurry is mixed with the second binder to obtain a spray precursor liquid;

[0057] The spray precursor liquid was spray-dried and calcined to obtain silicon-aluminum microspheres;

[0058] The viscosity of the first adhesive is lower than that of the second adhesive;

[0059] The silicon-aluminum ratio in the amorphous silicon-based raw material is 10 or higher.

[0060] In this invention, the amorphous silicon-based raw material is a material that exhibits an amorphous structure under X-ray diffraction testing. Preferably, the silicon-to-aluminum ratio in the amorphous silicon-based raw material is 20 or higher, such as 20, 30, 40, 50, 60, 70, 80, 90, 100, 120, 140, 160 or higher, or any range between any two values.

[0061] Preferably, the amorphous silicon-based raw material is selected from at least one of diatomaceous earth, silica, and silicon dioxide.

[0062] The clay is a known sticky soil, that is, a soil in which water does not easily pass through and has good plasticity, preferably selected from at least one of kaolin, illite, and bentonite. The silica-alumina ratio of the clay is preferably less than 10, for example, it can be 0.1, 1, 2, 3, 4, 5, 6, 7, 8, 9, less than 10, or any range between any two values.

[0063] Preferably, the method further includes: refining the amorphous silicon-based raw material and / or clay before first mixing the amorphous silicon-based raw material, clay, first binder, and water. The amorphous silicon-based raw material and clay can be refined separately, or the mixture of the two can be refined simultaneously.

[0064] Preferably, the refining process is selected from at least one of ball milling, high-speed mechanical impact milling, and air jet milling.

[0065] Preferably, the refining process is performed such that the average particle size of the amorphous silicon-based raw material is below 8 μm.

[0066] Preferably, the refining conditions result in an average particle size of the clay of 8 μm or less.

[0067] Those skilled in the art can adjust the refinement conditions according to the actual situation. For example, when using a ball mill for refinement, the ball milling conditions may include a ball milling time of 1-5 hours and a rotation speed of 100-500 rpm. The ball milling can be carried out in a ball mill, preferably a planetary ball mill (such as the JC-QM series vertical planetary ball mill of Juchuang Environmental Protection).

[0068] Preferably, the viscosity (25°C) of the first adhesive is 3-15 mPa·s, for example, 3, 5, 10, 15 mPa·s or more, or any range between any two values.

[0069] Preferably, the viscosity (25°C) of the second adhesive is 15-30 mPa·s, for example, 15, 20, 25, 30 mPa·s or more, or any range between any two values.

[0070] The viscosity is the kinetic viscosity at 25°C, measured using a rotational viscometer.

[0071] Preferably, the first adhesive and the second adhesive are each independently selected from at least one of aluminum sol, silica sol, and water glass.

[0072] In this invention, preferably, the first adhesive and the second adhesive have the same acidity or alkalinity, that is, both are acidic, alkaline, or neutral.

[0073] All adhesives used in this invention are commercially available, and their solid content is not particularly limited, preferably 10-50 wt%, such as 10, 15, 20, 25, 30, 35, 40, 45, 50 wt%, and any range between any two values, more preferably 15-40 wt%.

[0074] Preferably, on a dry basis, the amount of the amorphous silicon-based raw material is 1-20 parts by weight relative to 1 part by weight of clay, for example, 1, 2, 4, 6, 8, 10, 12, 14, 16, 18, 20 parts by weight and any range between any two values, and the amount of the first binder is 0.1-0.8 parts by weight, for example, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8 parts by weight and any range between any two values.

[0075] Preferably, the amount of water used is 5-60 parts by weight compared to 1 part by weight of dry clay, such as 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60 parts by weight, or any range between any two values.

[0076] Preferably, on a dry basis, the weight ratio of the second binder to the mixed soil slurry is 1:1-5, such as 1:1, 1:1.5, 1:2, 1:2.5, 1:3, 1:3.5, 1:4, 1:4.5, 1:5, and any range between any two values.

[0077] Preferably, the proportions of each component are such that the viscosity (25°C) of the spray precursor liquid is in the range of 0.2-3 mPa·s, for example, 0.2, 0.5, 1, 1.5, 2, 2.5, 3 mPa·s or more, or any range between any two values.

[0078] Preferably, the solid content of the pre-spray slurry is 20-40 wt%, such as 20, 22, 24, 26, 28, 30, 32, 34, 36, 38, 40 wt%, or any range between any two values.

[0079] In this invention, the solid content is determined according to the standard method of NB / SH / T 0953-2017, and the dry basis mass is the product of the solid content and the mass.

[0080] In this invention, the mixing method can be a conventional method in the art, such as dispersion, stirring, shaking, ball milling, or homogenization. When the mixing method is ball milling, the conditions are as described above. When the mixing method is homogenization, it can be carried out in a homogenizer (such as a digital display homogenizer, like the German IKA ULTRA-TURRAX high-speed disperser), and the homogenization conditions can include a homogenization time of 0.1-1 h and a rotation speed of 30,000-80,000 rpm. Preferably, the first mixing method is ball milling. Preferably, the second mixing method is homogenization.

[0081] Preferably, the average particle size of the solid particles in the mixed soil slurry is less than 8 μm.

[0082] In this invention, spray drying is performed using a spray drying tower or a high-speed centrifugal spray dryer (such as the Kinda Drying LPG high-speed centrifugal spray dryer). Preferably, the spray drying conditions include: a spray nozzle orifice diameter of 2.8-3.4 mm and an inlet temperature of 150-300°C.

[0083] Preferably, the calcination conditions include: a temperature of 500-600℃ and a time of 3-6 hours.

[0084] It should be understood that the obtained silicon-aluminum microspheres can be further processed, such as crystallization or loading of active components, to obtain different types of products. Those skilled in the art can choose according to their needs, which will not be elaborated further.

[0085] The third aspect of the present invention provides silicon-aluminum microspheres prepared by the method described above.

[0086] The fourth aspect of the present invention provides the use of the microspheres described above in the preparation of microsphere catalysts.

[0087] The following embodiments will further illustrate the present invention, but are not intended to limit the invention.

[0088] The particle size of the clay powder and microspheres was tested according to NB / SH / T 0951-2017. Test instrument: Malvern Mastersizer 2000.

[0089] The solid content was determined according to the standard method of NB / SH / T 0953-2017.

[0090] The dry basis mass is the product of solid content and mass.

[0091] The aspect ratio (b / l) and sphericity index (Q) are both quantitative tests of sphericity, performed using an image particle analyzer. The tests are conducted according to the following methods:

[0092] According to standard ISO-13322-2, the image particle analyzer consists of a circulating dispersion system and a microscope imaging system, forming an image particle size and morphology analysis system. In actual operation, after the sample is placed in the circulating system, the system will automatically circulate and disperse it. The digital camera captures particle images from the microscope and transmits them to the computer. The particle image processing and analysis software processes and analyzes the images to obtain quantitative results.

[0093] Aspect ratio (b / l) is measured by the particle width X. c,min and particle length (X) Feret The ratio of ,max) is used to obtain the particle length. Here, particle length refers to the maximum Feret radius (X). Feret,max ), that is, the distance between two parallel tangents at the two farthest points on the boundary of a particle (e.g. Figure 4 (As shown). The maximum distance between two boundary points perpendicular to the scanning direction is defined as X, obtained by scanning particles layer by layer along a certain direction. c (like Figure 5 (As shown). Scanning in different directions yields different X values. c Take X c All minimum values ​​are taken as minimum X c , represented as X c,min In actual testing, 32 X-rays were tested on a single particle along different directions. c Take its minimum value (X) c,min ); Test 32 X Feret Take its maximum value (X) Feret,max Q = b / l ≥ 0.9, meaning Q represents the percentage of particles that satisfy b / l ≥ 0.9 out of all particles.

[0094] The b / l of each particle is calculated according to formula (1), and the aspect ratio of the sample containing multiple particles is obtained by image analysis software.

[0095]

[0096] The mesoporous surface area, specific surface area, pore volume (total pore volume), and pore size distribution were measured using the low-temperature nitrogen adsorption capacity method. Experimental instrument: Micromeritics ASAP2400 static nitrogen adsorption instrument. Experimental conditions: The sample was degassed under vacuum at 1.33 Pa and 300 °C for 4 h, then contacted with liquid nitrogen at 77 K for isothermal adsorption / desorption. Adsorption / desorption isotherms were measured, and the specific surface area and pore volume were calculated using the BET formula.

[0097] The silicon-to-aluminum ratio was quantitatively characterized by X-ray fluorescence. Experimental instrument: Rigaku Electric Industries, Ltd., Japan, X-ray fluorescence spectrometer 3271E. Experimental conditions: powder samples were pressed into tablets, rhodium target was used, excitation voltage was 50 kV, excitation current was 50 mA, and the intensity of each element's spectral line was detected using a scintillation counter and a proportional counter. Quantitative and semi-quantitative analysis of elemental content was performed using the external standard method.

[0098] The viscosity is the kinetic viscosity at 25°C, tested according to the ASTM D445-04 standard test method for kinematic viscosity of transparent and opaque liquids (and the calculation of kinetic viscosity).

[0099] The straight pipe wear index was tested according to the "Determination of Wear Index of Catalytic Cracking Catalyst - Straight Pipe Method (NB / SH / T 0964-2017)".

[0100] The water pore volume was tested according to the ASTM standard "Standard Guide for Determination of Pore Volume of Powdered Catalysts and Catalyst Carriers by Water Adsorption" (D8393-21).

[0101] Diatomite, silica, kaolin, bentonite, and illite were all purchased from Jushi Mineral Products Processing Plant in Lingshou County, Hebei Province. Their chemical composition and silica-alumina ratio are shown in Table 1.

[0102] Table 1

[0103]

[0104] Note: The silicon-to-aluminum ratio in the table is the molar ratio of SiO2 to Al2O3 molecules.

[0105] Ball milling was carried out in a vertical planetary ball mill (JC-QM-0.4) by Juchuang Environmental Protection, and spray drying was carried out in a high-speed centrifugal spray dryer for LPG by Jianda Drying.

[0106] Unless otherwise specified, the room temperature in the following examples and comparative examples is 25±3℃.

[0107] Example 1

[0108] (1) Preparation of fine powder of amorphous silicon-based raw material: diatomaceous earth was fully ball-milled (350 rpm, ball-milled for 2 hours) to obtain fine powder with an average particle size of 4.2 μm.

[0109] (2) Preparation of clay fine powder: Kaolin was fully ball-milled (300 rpm, ball-milling for 2 hours) to obtain clay fine powder with an average particle size of 5.5 μm.

[0110] (3) Preparation of mixed soil slurry: 250.0g of amorphous silicon-based raw material, 44.8g of clay powder, 308.6g of water, and 40.8g of first binder (sodium-stabilized low-viscosity aluminum sol, Qingdao Junqiang New Materials Co., Ltd., solid content 21.7%, viscosity 4.7mPa·s) were mixed and ball-milled thoroughly (300rpm, ball milling for 2 hours) to obtain mixed soil slurry with an average particle size of 5.2μm.

[0111] (4) Spray granulation: Add 346.6g of the second binder (sodium-stabilized high-viscosity aluminum sol, Qingdao Junqiang New Materials Co., Ltd., solid content 22.0%, viscosity 16.5mPa·s) to the mixed soil slurry obtained in step (3), and mechanically mix it using an IKA ULTRA-TURRAX high-speed disperser (stirring speed 30000 rpm, homogenization for 20 minutes) to obtain the spray precursor liquid with a viscosity of 0.6mPa·s.

[0112] The obtained spray precursor liquid was spray-dried, and the spray-drying conditions included: a spray nozzle orifice diameter of 3 mm and an inlet temperature of 260°C.

[0113] (5) The microspheres obtained by spraying were calcined at 550℃ for 4 hours to obtain silicon-aluminum microspheres. Figure 1 The images are shown at 500x magnification using a scanning electron microscope (SEM). Specific chemical composition, sphericity, straight tube wear coefficient, average particle size (D50, D90 / D10), specific surface area, and pore volume information are shown in Tables 2-5.

[0114] Example 2

[0115] (1) Preparation of fine powder of amorphous silicon-based raw material: Silica was fully ball-milled (350 rpm, ball-milled for 3 hours) to obtain fine powder with an average particle size of 3.5 μm.

[0116] (2) Preparation of clay fine powder: Kaolin was fully ball-milled (300 rpm, ball-milled for 1 hour) to obtain clay fine powder with an average particle size of 6.4 μm.

[0117] (3) Preparation of mixed soil slurry: 250.0g of amorphous silicon-based raw material, 27.2g of clay powder, 388.3g of water, and 38.9g of first binder (sodium-stabilized low-viscosity aluminum sol, Qingdao Junqiang New Materials Co., Ltd., solid content 21.7%, viscosity 6.7mPa·s) were mixed and fully ball-milled (300rpm, ball-milling for 2.5 hours) to obtain mixed soil slurry with an average particle size of 5.4μm.

[0118] (4) Spray granulation: Add 342.0g of the second binder (sodium-stabilized high-viscosity aluminum sol, Qingdao Junqiang New Materials Co., Ltd., solid content 27%, viscosity 21.1mPa·s) to the mixed soil slurry obtained in step (3), and mechanically mix it using an IKA ULTRA-TURRAX high-speed disperser (stirring speed 30000 rpm, homogenization for 20 minutes) to obtain the spray precursor liquid with a viscosity of 1.1mPa·s.

[0119] The obtained spray precursor liquid was spray-dried, and the spray-drying conditions included: a spray nozzle orifice diameter of 3 mm and an inlet temperature of 250°C.

[0120] (5) The microspheres obtained by spraying were calcined at 550℃ for 4 hours to obtain silicon-aluminum microspheres. The specific chemical composition, sphericity, straight tube wear coefficient, average particle size D50, D90 / D10, specific surface area and pore volume information are shown in Tables 2-5.

[0121] Example 3

[0122] (1) Preparation of fine powder of amorphous silicon-based raw material: diatomaceous earth was fully ball-milled (300 rpm, ball-milled for 4 hours) to obtain fine powder with an average particle size of 2.5 μm.

[0123] (2) Preparation of clay fine powder: Bentonite was fully ball-milled (300 rpm, ball-milling for 2 hours) to obtain clay fine powder with an average particle size of 4.5 μm.

[0124] (3) Preparation of mixed soil slurry: 250.0g of amorphous silicon-based raw material, 20.6g of clay powder, 629.2g of water, and 27.4g of first binder (ammonia-stabilized low-viscosity silica sol, Qingdao Junqiang New Materials Co., Ltd., solid content 30.0%, viscosity 8.5mPa·s) were mixed and fully ball-milled (300rpm, ball-milling for 2 hours) to obtain mixed soil slurry with an average particle size of 4.7μm.

[0125] (4) Spray granulation: Add 251.9g of the second binder (ammonia-stabilized high-viscosity silica sol, Qingdao Junqiang New Materials Co., Ltd., solid content 30.1%, viscosity 25.0mPa·s) to the mixed soil slurry obtained in step (3), and mechanically mix it using an IKA ULTRA-TURRAX high-speed disperser (stirring speed 25000 rpm, homogenization for 20 minutes) to obtain the spray precursor liquid with a viscosity of 1.5mPa·s.

[0126] The obtained spray precursor liquid was spray-dried, and the spray drying conditions included: a spray nozzle orifice diameter of 3 mm and an inlet temperature of 255°C.

[0127] (5) The microspheres obtained by spraying were calcined at 550℃ for 4 hours to obtain silicon-aluminum microspheres. The specific chemical composition, sphericity, straight tube wear coefficient, average particle size D50, D90 / D10, specific surface area and pore volume information are shown in Tables 2-5.

[0128] Example 4

[0129] (1) Preparation of fine powder of amorphous silicon-based raw material: diatomaceous earth was fully ball-milled (350 rpm, ball-milled for 3 hours) to obtain fine powder with an average particle size of 4.2 μm.

[0130] (2) Preparation of clay fine powder: illite was fully ball-milled (300 rpm, ball-milled for 2 hours) to obtain clay fine powder with an average particle size of 3.5 μm.

[0131] (3) Preparation of mixed soil slurry: 250.0g of amorphous silicon-based raw material, 17.9g of clay powder, 800.0g of water, and 23.2g of first binder (low-viscosity sodium-stabilized silica sol, Qingdao Junqiang New Materials Co., Ltd., solid content 35%, viscosity 13.2mPa·s) were mixed and ball-milled thoroughly (300rpm, ball milling for 2 hours) to obtain mixed soil slurry with an average particle size of 6.0μm.

[0132] (4) Spray granulation: Add 220.5g of the second binder (sodium-stabilized high-viscosity silica sol, Qingdao Junqiang New Materials Co., Ltd., solid content 35%, viscosity 27.6mPa·s) to the mixed soil slurry obtained in step (3), and mechanically mix it using an IKA ULTRA-TURRAX high-speed disperser (stirring speed 30000 rpm, homogenization for 20 minutes) to obtain the spray precursor liquid with a viscosity of 1.8mPa·s.

[0133] The obtained spray precursor liquid was spray-dried, and the spray-drying conditions included: a spray nozzle orifice diameter of 3 mm and an inlet temperature of 260°C.

[0134] (5) The microspheres obtained by spraying were calcined at 550℃ for 4 hours to obtain silicon-aluminum microspheres. The specific chemical composition, sphericity, straight tube wear coefficient, average particle size D50, D90 / D10, specific surface area and pore volume information are shown in Tables 2-5.

[0135] Comparative Example 1

[0136] The procedure was followed as described in Example 1, except that diatomaceous earth was used instead of clay in the preparation of microspheres. The average particle size of the resulting mixed soil slurry was 5.0 μm.

[0137] Figure 2 The obtained product is shown in a scanning electron microscope (SEM) image magnified 500 times. The sphericity, average particle size D50 and D90 / D10 information of the obtained product are shown in Table 3.

[0138] Comparative Example 2

[0139] The procedure was carried out according to the method described in Example 1, except that an equal mass of kaolin was used instead of diatomaceous earth for the preparation of microspheres.

[0140] Figure 3 The obtained product is shown in a scanning electron microscope (SEM) image magnified 500 times. Information on its sphericity, average particle size D50 and D90 / D10 is shown in Table 3.

[0141] Comparative Example 3

[0142] The procedure was performed according to the method described in Example 1, except that an equal mass of quartz was used instead of diatomaceous earth for the preparation of microspheres.

[0143] The sphericity, average particle size (D50), and D90 / D10 of the obtained products are shown in Table 3.

[0144] Comparative Example 4

[0145] The procedure was carried out according to the method described in Example 1, except that an equal mass of high-silica ZSM-5 molecular sieve (silicon-aluminum molecular molar ratio of 200, microporous crystal, Nankai Catalyst Factory) was used instead of diatomaceous earth for the preparation of microspheres.

[0146] The sphericity, average particle size (D50), and D90 / D10 of the obtained products are shown in Table 3.

[0147] Comparative Example 5

[0148] The method described in Example 1 is followed, except that a second adhesive of equal dry weight is used instead of the first adhesive.

[0149] The sphericity, average particle size (D50), and D90 / D10 of the obtained products are shown in Table 3.

[0150] Comparative Example 6

[0151] The procedure is performed according to the method described in Example 1, except that a first adhesive of equal dry basis weight is used instead of a second adhesive.

[0152] The sphericity, average particle size (D50), and D90 / D10 of the obtained products are shown in Table 3.

[0153] Comparative Example 7

[0154] The method described in Example 1 is followed, except that the order of use of the first adhesive and the second adhesive is reversed, that is, the second adhesive is used first, and then the first adhesive is used.

[0155] The sphericity, average particle size (D50), and D90 / D10 of the obtained products are shown in Table 3.

[0156] Comparative Example 8

[0157] The method described in Example 1 is followed, except that the amorphous silicon-based raw material, clay, first binder, second binder and water are mixed simultaneously. The mixing method includes: first, ball milling (300 rpm, ball milling for 2 hours), and then mechanical mixing using an IKA ULTRA-TURRAX high-speed disperser (stirring rate of 30,000 rpm, homogenization for 20 minutes) to obtain the spray precursor liquid.

[0158] The sphericity, average particle size (D50), and D90 / D10 of the obtained products are shown in Table 3.

[0159] Table 2

[0160]

[0161] Note: The silicon-to-aluminum ratio in the table is the molar ratio of SiO2 / Al2O3 molecules.

[0162] Table 3

[0163]

[0164]

[0165] Table 4

[0166] serial number Water droplet method orifice volume (mL / g) Straight pipe wear index (wt% / h) Example 1 0.26 1.0 Example 2 0.30 1.8 Example 3 0.28 0.39 Example 4 0.28 1.6

[0167] Table 5

[0168]

[0169] Note: S BET S represents the total specific surface area. micro S represents the specific surface area of ​​the micropores. meso V represents the specific surface area of ​​the mesoporous structures. total V is the total pore volume. micro For micropore volume, V meso The volume is the mesopore volume.

[0170] The sphericity index (Q) of the products prepared in Comparative Examples 1-8 was all below 30, and the particle size distribution contained a large number of fragments. From a physical property point of view, they no longer belonged to microspheres and did not meet the requirements of the water droplet volume method test. Moreover, in the straight pipe wear index test, the mass loss was all above 30% (i.e., straight pipe wear index > 30).

[0171] From scanning electron microscope images ( Figure 1 As can be seen, the silicon-aluminum microspheres obtained by this invention show no obvious breakage, have a relatively smooth surface, and possess high sphericity. Table 3 shows that the aspect ratio of the silicon-aluminum microspheres obtained by this invention is between 0.93 and 0.96, and the sphericity index is between 88 and 96, exhibiting high sphericity. Simultaneously, the average particle size is between 65 and 80 micrometers, with a narrow particle size distribution range and a D90 / D10 ratio between 2 and 2.8.

[0172] As shown in Table 4, the wear index of the silicon-aluminum microspheres obtained in this invention is between 0.3-2 wt% / h, indicating high strength and good wear resistance. As shown in Table 5, the silicon-aluminum microspheres obtained in this invention are rich in mesoporous structures with a high mesoporous specific surface area (40-65 μm²). 2 / g), large mesopore volume (0.08-0.12cm) 3 / g).

[0173] In addition, the bulk density of the silicon-aluminum microspheres was measured to be 0.6-0.9, which is not given in the table.

[0174] Conversely, when preparing microspheres using a comparative method, it is difficult to obtain complete, highly spherical microspheres; numerous fragments and incomplete spheres (such as...) can be observed in electron micrographs. Figure 2 , Figure 3 (As shown). The comparative example exhibits low sphericity (sphericity index less than 30), wide particle size distribution (D90 / D10 both greater than 6), low strength (straight tube wear index higher than 30wt% / h), and relatively low mesoporous content (mesoporous specific surface area less than 20m²). 2 / g, mesopore volume less than 0.05cm 3 / g).

[0175] Therefore, it can be seen that the technical solution of the present invention can prepare silicon-aluminum microspheres with better performance, and the prepared silicon-aluminum microspheres are suitable for industrial fluidized bed process conditions.

[0176] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A silicon-aluminum microsphere, characterized in that, The microspheres have an aspect ratio (b / l) of 0.9 or higher and a sphericity index (Q) of 88 or higher. The ratio of D90 to D10 of the microspheres is less than 2.8; The wear coefficient of the silicon-aluminum microspheres in the straight tube is 0.3-2wt% / h; The silicon-aluminum microspheres contain mesopores with a specific surface area of ​​40-65 m². 2 / g, mesopore volume is 0.08-0.12cm³ 3 / g.

2. The silicon-aluminum microspheres according to claim 1, wherein, The microspheres have an aspect ratio (b / l) of 0.95 or higher and a sphericity index (Q) of 93 or higher; and / or Wherein, the straight tube wear coefficient of the silicon-aluminum microspheres is 0.3-1.2wt% / h; and / or The bulk density of the silicon-aluminum microspheres is 0.6-0.

9.

3. The silicon-aluminum microspheres according to claim 1 or 2, wherein, The microspheres contain 40-97 wt% silica and 3-60 wt% alumina; and / or The BET specific surface area of ​​the microspheres is 40-70 m². 2 / g, total pore volume is 0.08-0.12 cm³ 3 / g, microporous specific surface area 0.5-3 m² 2 / g, micropore volume 0.001-0.01 cm³ 3 / g.

4. A method for preparing silicon-aluminum microspheres, characterized in that, The method includes: mixing amorphous silicon-based raw materials, clay, a first binder and water to obtain a mixed soil slurry; The mixed soil slurry is mixed with the second binder to obtain a spray precursor liquid; The spray precursor liquid was spray-dried and calcined to obtain silicon-aluminum microspheres; The viscosity of the first adhesive is lower than that of the second adhesive; The silicon-aluminum ratio in the amorphous silicon-based raw material is 10 or higher; The viscosity (25°C) of the first adhesive is 3-15 mPa·s; The viscosity (25℃) of the second adhesive is 15-30 mPa·s; On a dry basis, the amount of the amorphous silicon-based raw material is 1-20 parts by weight relative to 1 part by weight of clay, and the amount of the first binder is 0.1-0.8 parts by weight. Compared to 1 part by weight of dry clay, the amount of water used is 5-60 parts by weight; On a dry basis, the weight ratio of the second binder to the mixed soil slurry is 1:1-5; The first mixing method is ball milling; The second mixing method is homogenization.

5. The method according to claim 4, wherein, The amorphous silicon-based raw material has a silicon-to-aluminum ratio of 20 or higher; and / or The clay is selected from at least one of kaolin, illite, and bentonite; and / or The first adhesive and the second adhesive are each independently selected from at least one of aluminum sol, silica sol, and water glass.

6. The method according to claim 5, wherein, The amorphous silicon-based raw material is selected from at least one of diatomaceous earth, silica, and silicon dioxide.

7. The method according to any one of claims 4-6, wherein, The average particle size of the solid particles in the mixed soil slurry is less than 8 μm.

8. The method according to claim 7, wherein, The method further includes: refining the amorphous silicon-based raw material and / or clay before first mixing the amorphous silicon-based raw material, clay, first binder and water; And / or, the refining process is selected from at least one of ball milling, high-speed mechanical impact milling, and air jet milling; And / or, the conditions of the refining process result in the average particle size of the amorphous silicon-based raw material being less than 8 μm; And / or, the conditions of the refining process result in an average particle size of the clay of less than 8 μm.

9. The method according to any one of claims 4-6 and 8, wherein, The dosage ratio of each component ensures that the viscosity (25℃) of the spray precursor liquid is in the range of 0.2-3 mPa·s; And / or, the solid content of the slurry before spraying is 20-40 wt%.

10. The method according to claim 7, wherein, The dosage ratio of each component ensures that the viscosity (25℃) of the spray precursor liquid is in the range of 0.2-3 mPa·s; And / or, the solid content of the slurry before spraying is 20-40 wt%.

11. The method according to any one of claims 4-6, 8, and 10, wherein, The conditions for spray drying include: a spray nozzle orifice diameter of 2.8-3.4 mm, and an inlet temperature of 150-300 ℃; and / or The roasting conditions include: a temperature of 500-600℃ and a time of 3-6 hours.

12. The method according to claim 7, wherein, The conditions for spray drying include: a spray nozzle orifice diameter of 2.8-3.4 mm, and an inlet temperature of 150-300 ℃; and / or The roasting conditions include: a temperature of 500-600℃ and a time of 3-6 hours.

13. The method according to claim 9, wherein, The conditions for spray drying include: a spray nozzle orifice diameter of 2.8-3.4 mm, and an inlet temperature of 150-300 ℃; and / or The roasting conditions include: a temperature of 500-600℃ and a time of 3-6 hours.

14. The silica-alumina microspheres prepared by the method according to any one of claims 4-13.

15. The use of the silica-alumina microspheres according to any one of claims 1-3 and 14 in the preparation of microsphere catalysts, adsorbents and fillers.

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