4A zeolite and preparation method thereof
Through cyclic crystallization and controlling the addition of sodium aluminosilicate gel slurry, the problem of small median particle size of 4A zeolite is solved, and the preparation of 4A zeolite with a median particle size in the range of 10 μm to 100 μm is achieved, which is suitable for a variety of applications.
Patent Information
- Application Number
- CN202411646858.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-18
- Publication Date
- 2025-03-11
AI Technical Summary
The median particle size of the existing 4A zeolite is small and difficult to meet certain application needs.
Through a preparation method, the sodium aluminosilicate gel slurry is used for multiple crystallization, and the gel slurry is added cycled to control the crystallinity and particle size, and finally 4A zeolite with a median particle size in the range of 10 μm to 100 μm was obtained.
The median particle size of 4A zeolite has been improved, the product crystallinity is > 90%, and the particle size is adjustable, which is suitable for different application fields.
Smart Images
Figure CN119591121A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the technical field of 4A zeolite preparation, and in particular to a 4A zeolite and a preparation method thereof. Background Art
[0002] At present, zeolite molecular sieves mainly include A-type, X-type and Y-type. The main body of A-type zeolite is 4A zeolite, which is used as raw powder to produce 3A and 5A zeolites through ion exchange to achieve different application purposes. The mainstream production process of 4A zeolite is hydrothermal synthesis, which uses aluminum source and silicon source according to a certain proportion of alumina, silicon dioxide, sodium oxide and water, and uses hydrothermal synthesis to produce 4A zeolite after mixing, beating, heating and crystallizing, separation and washing, and drying.
[0003] The 4A zeolite synthesized by traditional technology generally has a median particle size of 2 to 5 μm, which is relatively small and has a small control range; or large-grain 4A zeolite synthesized once by adjusting the hydrothermal synthesis conditions, but the median particle size of the crystals is 6 to 9 μm, indicating that the median particle size of the 4A zeolite is still relatively small. Summary of the invention
[0004] The present application provides a 4A zeolite and a preparation method thereof to solve the following technical problem: how to increase the median particle size of the 4A zeolite.
[0005] In a first aspect, the present application provides a method for preparing 4A zeolite, the method comprising:
[0006] S1, obtaining sodium aluminosilicate gel slurry;
[0007] S2, crystallizing the sodium aluminosilicate gel slurry having a first volume to obtain a slurry containing 4A zeolite with a preset crystallinity;
[0008] S3, adding the sodium aluminosilicate gel slurry having a second volume to the slurry containing 4A zeolite having a preset crystallinity to continue the crystallization;
[0009] S4, looping step S3 until a slurry containing 4A zeolite with a preset median particle size is obtained.
[0010] Optionally, the preset crystallinity is ≥35%.
[0011] Optionally, the preset crystallinity is 35% to 50%.
[0012] Optionally, the second volume is 20% to 30% of the first volume.
[0013] Optionally, the crystallization temperature is 75°C to 95°C.
[0014] Optionally, the preset median particle size is 10 μm to 100 μm.
[0015] Optionally, the step S3 is repeated until a slurry containing 4A zeolite with a preset median particle size is obtained, comprising:
[0016] S4, looping step S3 until a slurry containing 4A zeolite with a preset median particle size is obtained;
[0017] S5. Continuing to crystallize the slurry containing the 4A zeolite with a preset median particle size to obtain a target 4A zeolite product; wherein the target 4A zeolite product has a crystallinity of >90%.
[0018] Optionally, the initial sodium aluminosilicate gel slurry is obtained, comprising:
[0019] The sodium aluminate solution and the sodium silicate solution are mixed and slurried to obtain an initial sodium aluminosilicate gel slurry; wherein the temperature of the sodium aluminate solution and the sodium silicate solution is less than 35°C.
[0020] Optionally, the initial sodium aluminosilicate gel slurry contains SiO2, Al2O3, Na2O and H2O; wherein,
[0021] The molar ratio of SiO2 to Al2O3 is 1.8-2.0, the molar ratio of Na2O to Al2O3 is 2.0-3.0, and the molar ratio of H2O to Al2O3 is 120-160.
[0022] In a second aspect, the present application provides a 4A zeolite, which is prepared by the method described in any one of the embodiments of the first aspect.
[0023] The above technical solution provided by the embodiment of the present application has the following advantages compared with the prior art:
[0024] The preparation method of the 4A zeolite provided in an embodiment of the present application comprises: S1, obtaining a sodium aluminosilicate gel slurry; S2, crystallizing the sodium aluminosilicate gel slurry having a first volume to obtain a slurry containing a 4A zeolite with a preset crystallinity; S3, adding a second volume of the sodium aluminosilicate gel slurry to the slurry containing the 4A zeolite with a preset crystallinity to continue the crystallization; S4, repeating step S3 until a slurry containing a 4A zeolite with a preset median particle size is obtained. The sodium aluminosilicate gel slurry with a first volume is crystallized to obtain a slurry containing 4A zeolite with a preset crystallinity. At this time, the sodium aluminosilicate gel slurry in the crystallization reaction system is crystallized according to a certain spatial structure. The sodium aluminosilicate gel slurry with a second volume is added to the slurry containing 4A zeolite with a preset crystallinity to continue crystallization. Step S3 is repeated to continuously provide the crystallization system with the sodium aluminosilicate gel slurry with a second volume to provide raw materials for the crystal growth of 4A zeolite, so that the crystal structure of 4A zeolite continues to grow, and the growth is maintained to continuously obtain large particles of 4A zeolite, until 4A zeolite with a preset median particle size is obtained, thereby achieving an increase in the median particle size of 4A zeolite. BRIEF DESCRIPTION OF THE DRAWINGS
[0025] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.
[0026] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the embodiments or the description of the prior art. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.
[0027] Figure 1 A schematic flow chart of a method for preparing 4A zeolite provided in an embodiment of the present application;
[0028] Figure 2 This is a scanning electron microscope image of a 4A zeolite provided in Example 4 of the present application (magnification is 1000×);
[0029] Figure 3 This is a scanning electron microscope image of a 4A zeolite provided in Example 4 of the present application (magnification is 2500×). DETAILED DESCRIPTION
[0030] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.
[0031] Various embodiments of the present application may be presented in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity, and should not be understood as a rigid limitation on the scope of the present application; therefore, the range description should be considered to have specifically disclosed all possible sub-ranges and single numerical values within the range. For example, the range description from 1 to 6 should be considered to have specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single numbers within the range, such as 1, 2, 3, 4, 5 and 6, which apply regardless of the range. In addition, whenever a numerical range is indicated herein, it is meant to include any cited number (fractional or integer) within the indicated range.
[0032] In this application, unless otherwise specified, the directional words used, such as "upper" and "lower", refer specifically to the directions of the drawings in the accompanying drawings. In addition, in the description of the specification of this application, the terms "include", "comprise", etc. mean "including but not limited to". In the proportional relationship involved in this article, the parameters that need to be described by proportion should be understood as the first term of the proportional formula in the order of description, and the proportional numbers should be understood as the second term of the proportional formula. For example, the molar ratio of substance A, substance B and substance C is 1:2:3, then substance A, substance B and substance C should correspond one-to-one with the proportional numbers in the proportional formula in the order of description, that is, the mole of substance A: the mole of substance B: the mole of substance C = 1:2:3.
[0033] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in this application can be purchased from the market or prepared by existing methods.
[0034] In a first aspect, the present application provides a method for preparing 4A zeolite. Figure 1 A schematic diagram of a process for preparing 4A zeolite provided in the examples of the present application; see Figure 1 , the method comprising:
[0035] S1, obtaining sodium aluminosilicate gel slurry;
[0036] In some embodiments, the initial sodium aluminosilicate gel slurry is obtained, comprising:
[0037] The sodium aluminate solution and the sodium silicate solution are mixed and slurried to obtain an initial sodium aluminosilicate gel slurry; wherein the temperature of the sodium aluminate solution and the sodium silicate solution are both less than 35°C.
[0038] In the embodiment of the present application, a complex chemical reaction will occur during the mixing and slurrying process of the sodium aluminate solution and the sodium silicate solution, and a polymer structure of aluminosilicate can be formed. During the chemical reaction process, the polymer structure of the aluminosilicate gradually forms a gel-like substance, thereby obtaining an initial sodium aluminosilicate gel slurry. The sodium aluminate solution and the sodium silicate solution are in contact with each other, and a chemical reaction occurs to generate an amorphous sodium aluminosilicate gel. Low temperature conditions of <35°C are conducive to the generation of amorphous sodium aluminosilicate gel and full mixing, thereby avoiding the generation of impurities in the subsequent generation of crystal nuclei. Exemplarily, the temperature of the sodium aluminate solution and the sodium silicate solution can be 34°C, 33°C, 32°C, 31°C, 30°C, etc. In addition, the method for obtaining the above-mentioned sodium aluminate solution may include: utilizing the characteristics of aluminum hydroxide as an amphoteric compound, dissolving aluminum hydroxide in a sodium hydroxide solution, preparing it according to αk (Na2O / Al2O3, molar ratio) of 1.2 to 2.0, heating to dissolve aluminum hydroxide in the sodium hydroxide solution, and obtaining a sodium aluminate solution; or the intermediate product sodium aluminate solution in the alumina production process is directly used as the raw material sodium aluminate solution of the embodiment of the present application. The SiO2 concentration of the above-mentioned sodium silicate solution can be 80g / l to 160g / l, and the SiO2 concentration can be adjusted by liquid caustic soda or water.
[0039] In some embodiments, the initial sodium aluminosilicate gel slurry contains SiO2, Al2O3, Na2O and H2O; wherein,
[0040] The molar ratio of SiO2 to Al2O3 is 1.8-2.0, the molar ratio of Na2O to Al2O3 is 2.0-3.0, and the molar ratio of H2O to Al2O3 is 120-160.
[0041] In the embodiment of the present application, the indexes of SiO2, Al2O3, Na2O and H2O in the initial sodium aluminosilicate gel slurry are reasonably designed to fully realize the subsequent nucleation and crystal growth of 4A type zeolite. For example, the molar ratio of SiO2 to Al2O3 can be 1.8, 1.9, 2.0, etc.; the molar ratio of Na2O to Al2O3 can be 2.0, 2.3, 2.5, 2.8, 3.0, etc.; the molar ratio of Na2O to Al2O3 can be 120, 130, 140, 150, 160, etc.
[0042] S2, crystallizing the sodium aluminosilicate gel slurry having a first volume to obtain a slurry containing 4A zeolite with a preset crystallinity;
[0043] S3, adding the sodium aluminosilicate gel slurry having a second volume to the slurry containing 4A zeolite having a preset crystallinity to continue the crystallization;
[0044] S4, looping step S3 until a slurry containing 4A zeolite with a preset median particle size is obtained.
[0045] In an embodiment of the present application, the sodium aluminosilicate gel slurry having a first volume is crystallized to obtain a slurry containing 4A zeolite with a preset crystallinity. At this time, the sodium aluminosilicate gel slurry in the crystallized reaction system is crystallized according to a certain spatial structure. The sodium aluminosilicate gel slurry having a second volume is added to the slurry containing 4A zeolite with a preset crystallinity to continue crystallization. Step S3 is repeated to continuously provide the crystallization system with the sodium aluminosilicate gel slurry having a second volume to provide raw materials for the crystal growth of 4A zeolite, so that the crystal structure of 4A zeolite continues to grow, and the growth is maintained to continuously obtain large particles of 4A zeolite, until 4A zeolite with a preset median particle size is obtained, thereby achieving an increase in the median particle size of 4A zeolite.
[0046] 4A zeolite is an aluminosilicate mineral with molecular sieve function. Its chemical composition is Na 12 Al 12 Si 12 O 48 ·27H2O. Structurally, it belongs to the cubic crystal system and has a three-dimensional pore structure. These pores are formed by silicon-oxygen tetrahedrons and aluminum-oxygen tetrahedrons connected by shared oxygen atoms. The internal pore size is about That's why it's called 4A zeolite. Appearance and shape: Usually white powdery crystals with small and uniform particles. This powdery form allows it to be evenly dispersed in many application scenarios. Adsorption performance: It has strong adsorption capacity and can adsorb molecules with diameters smaller than its pore size. Ion exchange performance: The sodium ions in 4A zeolite are exchangeable. Under certain conditions, sodium ions can be exchanged with other cations. For example, in water, it can exchange with ions such as calcium and magnesium to reduce the hardness of water. This ion exchange performance plays an important role in water treatment.
[0047] In some embodiments, the predetermined crystallinity is ≥35%.
[0048] In some embodiments, the preset crystallinity is 35% to 50%.
[0049] In the embodiment of the present application, the preset crystallinity can be ≥35%, because the crystallization reaction process is controlled to complete crystal nucleation and enter the early stage of the crystal growth stage. If the preset crystallinity is lower than 35%, it means that the timing of adding the sodium aluminosilicate gel slurry again is too early, which may destroy the crystal structure being formed, resulting in uneven crystal growth or the generation of impurities, and the crystallization reaction nucleation process may not be over yet. At this time, the addition of the sodium aluminosilicate gel slurry with a second volume will continue the nucleation process, and the initial crystal nucleus will be continuously generated, resulting in excessive crystal nuclei, which is not conducive to the crystal growth of the later crystallization process, and ultimately leads to small particles of 4A zeolite, that is, small median particle size. Exemplarily, the preset crystallinity can be 35%, 36%, 37%, 38%, 39%, 40%, etc. In order to enable the crystallization system to obtain raw materials in time and thus promote the growth of crystals, sodium aluminosilicate gel slurry can be added again when the preset crystallinity is 35% to 50%. Exemplarily, the preset crystallinity can be 35%, 36%, 37%, 38%, 39%, 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49%, 50%, etc.
[0050] In some embodiments, the second volume is 20% to 30% of the first volume.
[0051] In an embodiment of the present application, the second volume can be 20% to 30% of the first volume, so that the sodium aluminosilicate gel slurry added again controls the growth of the crystal and no longer reacts to form crystal nuclei. If the second volume is higher than 30% of the first volume, it may cause the generation of crystal nuclei and excessive crystal nuclei, resulting in small particles of 4A zeolite; if the second volume is lower than 20% of the first volume, it may be difficult to provide enough sodium aluminosilicate gel slurry for crystal growth, so that it is difficult to provide sufficient power for crystallization growth, resulting in the cessation of crystal growth and no longer growing, which in turn leads to small particles of 4A zeolite. Exemplarily, the second volume can be 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, etc. of the first volume.
[0052] In some embodiments, the crystallization temperature is 75°C to 95°C.
[0053] In the embodiment of the present application, the crystallization temperature can be 75°C to 95°C, thereby providing sufficient energy for the crystallization system, so that the ions of silicon, aluminum, etc. that constitute the 4A zeolite can be better gathered and arranged around the crystal nucleus, promoting the crystallization process, and obtaining high-quality 4A zeolite crystals. Exemplarily, the crystallization temperature can be 75°C, 80°C, 85°C, 90°C, 95°C, etc.
[0054] In some embodiments, the preset median particle size is 10 μm to 100 μm.
[0055] In the embodiment of the present application, the large-particle 4A zeolite can be directly prepared by presetting the median particle size and adjusting the number of times the sodium aluminosilicate gel slurry having the second volume is added, and the median particle size of the 4A zeolite is adjustable within the range of 10 μm to 100 μm. Exemplarily, the preset median particle size can be 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, etc.
[0056] In some embodiments, the step S3 is repeated until a slurry containing 4A zeolite having a predetermined median particle size is obtained, comprising:
[0057] S4, looping step S3 until a slurry containing 4A zeolite with a preset median particle size is obtained;
[0058] S5. Continuing to crystallize the slurry containing the 4A zeolite with a preset median particle size to obtain a target 4A zeolite product; wherein the target 4A zeolite product has a crystallinity of >90%.
[0059] In the embodiment of the present application, the slurry containing 4A zeolite with a preset median particle size is further crystallized to improve the crystallinity of the 4A zeolite with a preset median particle size, thereby obtaining a target 4A zeolite product with a crystallinity of >90%.
[0060] Exemplarily, step S2 includes: according to the volume size of the crystallization tank and the preset median particle size target size of the 4A zeolite, taking a first volume of sodium aluminosilicate gel slurry into the crystallization tank, starting stirring and steaming to increase the temperature for crystallization, and when the crystallinity of the 4A zeolite in the crystallization tank reaches more than the preset crystallinity of 35%, adding a second volume of sodium aluminosilicate gel slurry to continue to keep warm for crystallization, and so on. Whenever the crystallinity of the 4A zeolite obtained by the crystallization reaches the preset crystallinity, adding a second volume of sodium aluminosilicate gel slurry to the crystallization reaction system to continue crystallization until the 4A zeolite with a preset median particle size is obtained, and stopping the addition of sodium aluminosilicate gel slurry, and continuing the crystallization process to achieve a crystallinity of 4A zeolite greater than 90%, to obtain the target 4A zeolite product.
[0061] Finally, after the entire crystallization process is completed, the slurry containing the target 4A zeolite product is passed through a filter press for solid-liquid separation, the crystallization mother liquor can be returned to the raw material preparation, the target 4A zeolite product solid is washed to a qualified pH <11, the qualified filter cake is dried and packaged as a product.
[0062] In summary, the preparation method of 4A zeolite provided in this application has at least the following advantages:
[0063] 1. The preparation method of the 4A zeolite is based on the gradual growth of the 4A zeolite. First, a sodium aluminate gel slurry is prepared by mixing a sodium aluminate solution and a sodium silicate solution as raw materials. During the crystallization process of the sodium aluminate gel slurry with the first volume, when the crystallinity of the 4A zeolite reaches a preset value, a second volume of sodium aluminate gel slurry is added to continuously provide raw materials for crystal growth. Silicon, aluminum and other components in the sodium aluminate gel slurry are the basic units for constructing the crystal structure of the 4A zeolite. As the crystallization proceeds, the crystal grows according to its specific lattice structure, and the second volume of sodium aluminate gel slurry is added cyclically to continuously provide growth raw materials for the 4A zeolite crystal structure being constructed, so that the crystal structure of the 4A zeolite can be continuously improved and expanded, which is conducive to the formation of large particles of 4A zeolite. Compared with the traditional method, a fixed volume one-time synthesis is performed using a reactor or a tank body. Under such working conditions, each local unit material component is formed according to a regular structure. When the reaction is completed, there is no supply of raw materials, and smaller zeolite particles are formed, and the reaction no longer continues to grow;
[0064] 2. The preset crystallinity determines the timing of adding sodium aluminosilicate gel slurry to the crystallization system. When the crystallinity reaches the preset value, it indicates that the crystal growth in the current crystallization stage has reached a certain extent. At this time, the demand for new raw materials increases, and the crystal structure is relatively stable, and can continue to accept the second volume of sodium aluminosilicate gel slurry for crystal growth;
[0065] 3. Control of median particle size By continuously adding the second volume of sodium aluminosilicate gel slurry, raw materials are continuously provided for crystal growth. During the crystallization process, the crystals of 4A zeolite keep growing, so that the particle size of the crystals continues to increase, and 4A zeolite with larger particles can be obtained. Therefore, this method can avoid the problem of limited crystal growth and smaller particle size due to the one-time addition of sodium aluminosilicate gel slurry.
[0066] In a second aspect, the present application provides a 4A zeolite, which is prepared by the method described in any one of the embodiments of the first aspect.
[0067] In the examples of the present application, the 4A zeolite prepared by the above method has a crystallinity of >90%, a median particle size of the product particles that is adjustable within the range of 10 μm to 100 μm, and has excellent dispersibility and fluidity.
[0068] The 4A zeolite is realized based on the preparation method of the above-mentioned 4A zeolite. The specific steps of the preparation method of the 4A zeolite can refer to the above-mentioned embodiment. Since the 4A zeolite adopts part or all of the technical solutions of the above-mentioned embodiment, it has at least all the beneficial effects brought by the technical solutions of the above-mentioned embodiment, which will not be repeated here one by one.
[0069] The present application will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are intended only to illustrate the present application and are not intended to limit the scope of the present application. The experimental methods for the unrecorded specific conditions in the following examples are usually measured according to national standards. If there is no corresponding national standard, then carry out according to general international standards, normal conditions or according to the conditions recommended by the manufacturer.
[0070] Example 1
[0071] A method for preparing 4A zeolite, comprising:
[0072] S11, obtaining sodium aluminosilicate gel slurry; specifically: dissolving industrial grade aluminum hydroxide in sodium hydroxide solution to obtain sodium aluminate solution, the sodium aluminate solution meets: Al2O3 concentration of 50g / l, Na2O concentration of 60g / l; diluting the sodium silicate solution with water to adjust the SiO2 concentration to 120g / l; mixing the sodium aluminate solution with the sodium silicate solution to obtain sodium aluminosilicate gel slurry; wherein the sodium aluminosilicate gel slurry meets the indicators: the molar ratio of SiO2 to Al2O3 is 1.9, the molar ratio of Na2O to Al2O3 is 2.6, and the molar ratio of H2O to Al2O3 is 160;
[0073] S21, crystallizing the sodium aluminosilicate gel slurry having a first volume to obtain a slurry containing 4A zeolite with a preset crystallinity; specifically, injecting the sodium aluminosilicate gel slurry having a first volume into a crystallization tank for crystallization, wherein the crystallization tank is directly heated by steam, and the volume of the crystallization tank is 1m 3 The first volume was 200 L, the temperature was raised to 90°C for crystallization, and the crystallinity was detected to reach 43% (preset crystallinity) after 1 hour;
[0074] S31, adding a second volume of sodium aluminosilicate gel slurry to a slurry containing 4A zeolite with a preset crystallinity to continue crystallization;
[0075] S41, looping step S31 until a slurry containing 4A zeolite with a preset median particle size is obtained; wherein the second volume is 25% of the first volume, the number of cycles of adding the second volume of sodium aluminosilicate gel slurry is 3; and the preset median particle size is 12 μm;
[0076] S51, continuing to crystallize the slurry containing 4A zeolite with a preset median particle size for 3 hours to obtain the target 4A zeolite product.
[0077] Example 2
[0078] S12, obtaining sodium aluminosilicate gel slurry; specifically: dissolving industrial grade aluminum hydroxide in sodium hydroxide solution to obtain sodium aluminate solution, the sodium aluminate solution meets: Al2O3 concentration of 50g / l, Na2O concentration of 60g / l; diluting the sodium silicate solution with water to adjust the SiO2 concentration to 120g / l; mixing the sodium aluminate solution with the sodium silicate solution to obtain sodium aluminosilicate gel slurry; wherein the sodium aluminosilicate gel slurry meets the indicators: the molar ratio of SiO2 to Al2O3 is 1.9, the molar ratio of Na2O to Al2O3 is 2.5, and the molar ratio of H2O to Al2O3 is 160;
[0079] S22, crystallizing the sodium aluminosilicate gel slurry having a first volume to obtain a slurry containing 4A zeolite with a preset crystallinity; specifically, injecting the sodium aluminosilicate gel slurry having a first volume into a crystallization tank for crystallization, wherein the crystallization tank is directly heated by steam, and the volume of the crystallization tank is 1m 3 The first volume was 100 L, the temperature was raised to 90°C for crystallization, and the crystallinity was detected to reach 38% (preset crystallinity) after 1 hour;
[0080] S32, adding a second volume of sodium aluminosilicate gel slurry to the slurry containing 4A zeolite with a preset crystallinity to continue crystallization;
[0081] S42, looping step S32 until a slurry containing 4A zeolite with a preset median particle size is obtained; wherein the second volume is 25% of the first volume, the number of cycles of adding the second volume of sodium aluminosilicate gel slurry is 6; and the preset median particle size is 35 μm;
[0082] S52, continuing to crystallize the slurry containing 4A zeolite with a preset median particle size for 3 hours to obtain the target 4A zeolite product.
[0083] Example 3
[0084] S13, obtaining sodium aluminosilicate gel slurry; specifically: dissolving industrial grade aluminum hydroxide in sodium hydroxide solution to obtain sodium aluminate solution, the sodium aluminate solution meets: Al2O3 concentration of 50g / l, Na2O concentration of 60g / l; diluting the sodium silicate solution with water to adjust the SiO2 concentration to 120g / l; mixing the sodium aluminate solution with the sodium silicate solution to obtain sodium aluminosilicate gel slurry; wherein the sodium aluminosilicate gel slurry meets the indicators: the molar ratio of SiO2 to Al2O3 is 2.0, the molar ratio of Na2O to Al2O3 is 2.5, and the molar ratio of H2O to Al2O3 is 160;
[0085] S23, crystallizing the sodium aluminosilicate gel slurry having a first volume to obtain a slurry containing 4A zeolite with a preset crystallinity; specifically, injecting the sodium aluminosilicate gel slurry having a first volume into a crystallization tank for crystallization, wherein the crystallization tank is directly heated by steam, and the volume of the crystallization tank is 1m 3 The first volume was 100 L, the temperature was raised to 90°C for crystallization, and the crystallinity was detected to reach 38% (preset crystallinity) after 1 hour;
[0086] S33, adding a second volume of sodium aluminosilicate gel slurry to the slurry containing 4A zeolite with a preset crystallinity to continue crystallization;
[0087] S43, repeating step S33 until a slurry containing 4A zeolite with a preset median particle size is obtained; wherein the second volume is 20% of the first volume, the number of cycles of adding the second volume of sodium aluminosilicate gel slurry is 9; and the preset median particle size is 55 μm;
[0088] S51, continuing to crystallize the slurry containing 4A zeolite with a preset median particle size for 3 hours to obtain the target 4A zeolite product.
[0089] Example 4
[0090] S14, obtaining sodium aluminosilicate gel slurry; specifically: dissolving industrial grade aluminum hydroxide in sodium hydroxide solution to obtain sodium aluminate solution, the sodium aluminate solution meets: Al2O3 concentration of 50g / l, Na2O concentration of 60g / l; diluting the sodium silicate solution with water to adjust the SiO2 concentration to 120g / l; mixing the sodium aluminate solution with the sodium silicate solution to obtain sodium aluminosilicate gel slurry; wherein the sodium aluminosilicate gel slurry meets the indicators: the molar ratio of SiO2 to Al2O3 is 1.9, the molar ratio of Na2O to Al2O3 is 2.5, and the molar ratio of H2O to Al2O3 is 160;
[0091] S24, crystallizing the sodium aluminosilicate gel slurry having a first volume to obtain a slurry containing 4A zeolite with a preset crystallinity; specifically, injecting the sodium aluminosilicate gel slurry having a first volume into a crystallization tank for crystallization, wherein the crystallization tank is directly heated by steam, and the volume of the crystallization tank is 1m 3 The first volume was 100 L, the temperature was raised to 90°C for crystallization, and the crystallinity was detected to reach 38% (preset crystallinity) after 1 hour;
[0092] S34, adding a second volume of sodium aluminosilicate gel slurry to the slurry containing 4A zeolite with a preset crystallinity to continue crystallization;
[0093] S44, looping step S34 until a slurry containing 4A zeolite with a preset median particle size is obtained; wherein the second volume is 20% of the first volume, the number of cycles of adding the second volume of sodium aluminosilicate gel slurry is 12; and the preset median particle size is 60 μm;
[0094] S54, continuing to crystallize the slurry containing 4A zeolite with a preset median particle size for 3 hours to obtain the target 4A zeolite product.
[0095] Comparative Example 1
[0096] A method for preparing 4A zeolite, comprising:
[0097] (1) obtaining a sodium aluminosilicate gel slurry; specifically, dissolving industrial-grade aluminum hydroxide in a sodium hydroxide solution to obtain a sodium aluminate solution, wherein the sodium aluminate solution satisfies: the concentration of Al2O3 is 50 g / l, and the concentration of Na2O is 60 g / l; the sodium silicate solution is diluted with water to adjust the concentration of SiO2 to 120 g / l; the sodium aluminate solution and the sodium silicate solution are mixed and slurried to obtain a sodium aluminosilicate gel slurry; wherein the sodium aluminosilicate gel slurry satisfies the following indicators: the molar ratio of SiO2 to Al2O3 is 1.9, the molar ratio of Na2O to Al2O3 is 2.6, and the molar ratio of H2O to Al2O3 is 160;
[0098] (2) The sodium aluminosilicate gel slurry is crystallized at one time, the crystallization temperature is 90°C, and the crystallization time is 4 hours to obtain 4A zeolite. Specifically, the sodium aluminosilicate gel slurry is poured into a crystallization tank for crystallization. The crystallization tank is directly heated by steam. The volume of the crystallization tank is 1m 3 .
[0099] The 4A zeolites prepared in Examples 1 to 4 and Comparative Example 1 were subjected to index tests, and the test results are shown in Table 1.
[0100] Table 1 Indicators of 4A zeolite
[0101] Serial number Target 4A zeolite product crystallinity Median particle size Example 1 93.5％ 12μm Example 2 93％ 35μm Example 3 92％ 55μm Example 4 93％ 60μm Comparative Example 1 95％ 3μm
[0102] As shown in Table 1, the preparation method of 4A zeolite provided in the embodiment of the present application directly prepares large-particle 4A zeolite by adding sodium aluminosilicate gel slurry step by step during the crystallization process, and the median particle size of the product is adjustable within the range of 10 μm to 100 μm. In contrast, in Comparative Example 1, the sodium aluminosilicate gel slurry is crystallized at one time, and the 4A zeolite is only 3 μm.
[0103] For example, the target 4A zeolite product prepared in Example 4 is a white powder, which is a 4A zeolite crystal phase detected by XRD, with a crystallinity of 93%. Figure 2 This is a scanning electron microscope image of a 4A zeolite provided in Example 4 of the present application (magnification is 1000×); Figure 3 This is a scanning electron microscope image of a 4A zeolite provided in Example 4 of the present application (magnification is 2500×); please refer to Figures 2-3 , indicating that the particle size is spherical when detected by electron microscope scanning, and the median particle size is 60μm when detected by Malvern particle size analyzer.
[0104] One or more technical solutions in the embodiments of the present application also have at least the following technical effects or advantages:
[0105] (1) In the embodiment of the present application, large particles of 4A zeolite can be directly prepared by adding sodium aluminosilicate gel slurry step by step during the crystallization process, and the median particle size of the product can be adjusted within the range of 10 μm to 100 μm;
[0106] (2) According to the needs of different application fields, the particle size of 4A zeolite is adjusted to achieve friendly compatibility with the particle sizes of other components during the application process, and the poor mixing effect caused by powder stratification due to the large difference in particle sizes of different components will not be achieved.
[0107] The above description is only a specific implementation of the present application, so that those skilled in the art can understand or implement the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features applied for herein.
Claims
1. A method for preparing 4A zeolite, the method comprising: S1, obtaining sodium aluminosilicate gel slurry; S2, crystallizing the sodium aluminosilicate gel slurry having a first volume to obtain a slurry containing 4A zeolite with a preset crystallinity; S3, adding the sodium aluminosilicate gel slurry having a second volume to the slurry containing 4A zeolite having a preset crystallinity to continue the crystallization; S4, looping step S3 until a slurry containing 4A zeolite with a preset median particle size is obtained.
2. The method according to claim 1, characterized in that: The preset crystallinity is ≥35%.
3. The method according to claim 2, characterized in that The preset crystallinity is 35% to 50%.
4. The method according to claim 1, characterized in that: The second volume is 20% to 30% of the first volume.
5. The method according to claim 1, characterized in that The crystallization temperature is 75°C to 95°C.
6. The method according to any one of claims 1 to 5, characterized in that: The preset median particle size is 10 μm to 100 μm.
7. The method according to claim 1, characterized in that The step S3 is repeated until a slurry containing 4A zeolite with a preset median particle size is obtained, comprising: S4, looping step S3 until a slurry containing 4A zeolite with a preset median particle size is obtained; S5. Continuing to crystallize the slurry containing the 4A zeolite with a preset median particle size to obtain a target 4A zeolite product; wherein the target 4A zeolite product has a crystallinity of >90%.
8. The method according to claim 1, characterized in that: The method of obtaining the initial sodium aluminosilicate gel slurry comprises: The sodium aluminate solution and the sodium silicate solution are mixed and slurried to obtain an initial sodium aluminosilicate gel slurry; wherein the temperature of the sodium aluminate solution and the sodium silicate solution are both less than 35°C.
9. The method according to claim 8, characterized in that The initial sodium aluminosilicate gel slurry contains SiO2, Al2O3, Na2O and H2O; wherein, The molar ratio of SiO2 to Al2O3 is 1.8-2.0, the molar ratio of Na2O to Al2O3 is 2.0-3.0, and the molar ratio of H2O to Al2O3 is 120-160.
10. A 4A zeolite, prepared by the method according to any one of claims 1 to 9.