Large-grain 3A zeolite molecular sieve raw powder and preparation method thereof

Abstract

The invention relates to large-grain 3A zeolite molecular sieve raw powder and a preparation method thereof, and belongs to the technical field of molecular sieve preparation. The method comprises the following steps: mixing a silicon source and an aluminum source according to a set silicon-aluminum molar ratio to obtain first mixed slurry, and controlling the molar ratio to be 1.9-1.92 to form a stable truncated hexahedron A-type molecular sieve structure; adding the silica-alumina gel seed crystal into the mixed slurry, and then carrying out first crystallization and second crystallization to realize accurate regulation and control of crystal nucleus generation and crystal growth and eliminate generation of mixed crystals and twin crystal nucleus agglomeration so as to obtain crystallized slurry; carrying out solid-liquid separation on the crystallized slurry, carrying out ion exchange for three times, and carrying out potassium ion exchange on sodium ions in a solid-phase substance to finally obtain large-grain 3A zeolite molecular sieve raw powder. The particle size of the 3A molecular sieve prepared by the method is 5-8 microns, the bulk specific gravity is greater than 0.8 g / ml, the saturated water adsorption is greater than 25.5% at the temperature of 25 DEG C and the relative humidity of 50%, the water adsorption is also greatly improved and is obviously higher than that of the 3A molecular sieve prepared by the prior art, and the filling rate and the utilization rate of 3A molecular sieve equipment are greatly improved.

Description

Technical Field

[0001] The present application relates to the technical field of molecular sieve preparation, and particularly relates to a large-crystalline 3A zeolite molecular sieve raw powder and a preparation method thereof. Background Art

[0002] Zeolite molecular sieves belong to alkali metal aluminosilicates, which are important basic materials and new functional materials. They have a structure of a uniform microporous cubic lattice, with a large specific surface area and pore volume, strong separation and selective adsorption, high thermal stability, chemical stability, a large variety, obvious individuality, and high added value. Among them, 3A molecular sieve is the most widely used. However, the average diameter (D50) of existing 3A molecular sieve raw powder particles is generally 2 μm to 5 μm, the bulk specific gravity is about 0.60 g / ml to 0.75 g / ml, and at 25°C and 50% relative humidity, the saturated water absorption is only 24.5% to 25.5%, which cannot fully meet industrial applications. Summary of the Invention

[0003] The present application provides a large-crystalline 3A zeolite molecular sieve raw powder and a preparation method thereof to solve the following technical problem: how to obtain a large-crystalline 3A zeolite molecular sieve raw powder.

[0004] In a first aspect, an embodiment of the present application provides a preparation method of a large-crystalline 3A zeolite molecular sieve raw powder, including the following steps:

[0005] Obtain a silica-alumina gel seed;

[0006] Mix a silicon source and an aluminum source to obtain a first mixed slurry;

[0007] Add the silica-alumina gel seed to the first mixed slurry to perform first crystallization and second crystallization to obtain a crystallized slurry; and,

[0008] Perform ion exchange on the crystallized slurry to obtain a large-crystalline 3A zeolite molecular sieve raw powder;

[0009] Wherein, the molar ratio of SiO 2 of the silicon source and Al 2 O 3 is SiO 2 :Al 2 O 3 = 1.9 to 1.92;

[0010] The reaction parameters of the first crystallization include at least one of the following parameters: the temperature of the first crystallization is 70°C - 75°C, and the holding time of the first crystallization is 5 h to 6 h;

[0011] The reaction parameters of the second crystallization include at least one of the following parameters: the temperature of the second crystallization is 90°C to 95°C, and the holding time is 4 h to 4.5 h.

[0012] Optionally, the ion exchange of the crystallization slurry to obtain the raw powder of large crystal 3A zeolite molecular sieve specifically includes:

[0013] Performing solid-liquid separation on the crystallization slurry to obtain a solid-phase substance;

[0014] Performing leaching and stirring washing on the solid-phase substance to obtain a second mixed slurry;

[0015] Performing an ion homogenization reaction on the second mixed slurry to obtain a homogenized slurry; and,

[0016] Performing solid-liquid separation on the homogenized slurry to obtain the raw powder of large crystal 3A zeolite molecular sieve.

[0017] Optionally, the performing of leaching and stirring washing on the solid-phase substance to obtain a second mixed slurry specifically includes:

[0018] Using a first potassium ion solution to perform primary leaching on the solid-phase substance in sequence;

[0019] Using a second potassium ion solution to perform secondary leaching on the solid-phase substance after the primary leaching;

[0020] Using a third potassium ion solution to perform pulping and stirring washing on the solid-phase substance after the secondary leaching to obtain a second mixed slurry;

[0021] Wherein, the concentrations of the first potassium ion solution, the second potassium ion solution, and the third potassium ion solution show an increasing trend.

[0022] Optionally, the concentration of the first potassium ion solution is 10 g / L to 20 g / L; and / or

[0023] the concentration of the second potassium ion solution is 20 g / L to 40 g / L; and / or

[0024] the concentration of the third potassium ion solution is 40 g / L to 60 g / L.

[0025] Optionally, the performing of solid-liquid separation on the crystallization slurry to obtain a solid-phase substance specifically includes:

[0026] Performing solid-liquid separation on the crystallization slurry to obtain a first solid-phase impurity;

[0027] Performing hot water pulping on the solid-phase impurity to obtain an impurity slurry;

[0028] Performing solid-liquid separation on the impurity slurry to obtain a solid-phase substance.

[0029] Optionally, the time of the ion homogenization reaction is 2 h to 4 h.

[0030] Optionally, the volume of the silica-alumina gel seed is 3 / 10000 to 10 / 10000 of the total volume of the mixture of the mixed slurry and the silica-alumina gel seed.

[0031] Optionally, obtaining the silica-alumina gel seed specifically includes:

[0032] Obtaining a seed silicon source and a seed aluminum source;

[0033] Mixing and reacting the seed silicon source and the seed aluminum source to obtain a silica-alumina gel seed;

[0034] Among them, the seed aluminum source satisfies at least one of the following conditions: the alumina concentration is 20 to 30 g / L, and the caustic coefficient is 10 - 13;

[0035] The seed silicon source satisfies at least one of the following conditions: the concentration of silicon dioxide is 17% to 20%, and the specific gravity is 1.25 to 1.4;

[0036] The SiO of the seed silicon source 2 and the Al of the seed aluminum source 2 O 3 The molar ratio of is SiO 2 :Al 2 O 3 = 10 to 13.

[0037] Optionally, mixing and reacting the seed aluminum source and the seed silicon source to obtain a silica-alumina gel seed specifically includes:

[0038] Mixing the silicon source and the aluminum source, stirring for a first set time to obtain a third mixed slurry;

[0039] Diluting the third mixed slurry by 10 times;

[0040] Stirring the diluted third mixed slurry for a second set time to obtain a silica-alumina gel seed;

[0041] Among them, the first set time is 0.5 to 1.5 h;

[0042] The second set time is 0.5 to 1.5 h.

[0043] In a second aspect, an embodiment of the present application provides a large crystal 3A zeolite molecular sieve raw powder, which is prepared by using the preparation method of the large crystal 3A zeolite molecular sieve raw powder according to any one of the embodiments of the first aspect.

[0044] The above technical solutions provided by the embodiments of the present application have the following advantages compared with the prior art:

[0045] An embodiment of the present application provides a large-crystalline 3A zeolite molecular sieve raw powder and a preparation method thereof. The preparation method includes obtaining a silica-alumina gel seed; mixing a silicon source and an aluminum source according to a set silicon-aluminum molar ratio to obtain a first mixed slurry, and controlling the molar ratio to be 1.9 to 1.92 to form a stable truncated hexahedron A-type molecular sieve structure; adding the silica-alumina gel seed to the mixed slurry, and then performing first crystallization and second crystallization to obtain a crystallized slurry; controlling the first crystallization time and the second crystallization time, aiming to precisely control the generation of crystal nuclei and the growth of crystals, and eliminate the generation of impurity crystals and the aggregation of twin crystal nuclei. At this time, the particles in the crystallized slurry already have a large-crystalline structure. Then, the crystallized slurry is subjected to ion exchange to achieve the exchange of potassium and sodium ions, and finally, a large-crystalline 3A zeolite molecular sieve raw powder is obtained. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] The accompanying drawings herein are incorporated into the specification and constitute a part of this specification, showing embodiments consistent with the present application, and are used together with the specification to explain the principles of the present application.

[0047] To more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, for those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0048] Figure 1 It is a schematic flow chart of a method for preparing a large-crystalline 3A zeolite molecular sieve raw powder according to some embodiments of the present application;

[0049] Figure 2 It is a schematic structural diagram of a large-crystalline 3A zeolite molecular sieve raw powder according to some embodiments of the present application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0050] To make the objectives, technical solutions, and advantages of the embodiments of the present application clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present application with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are some, but not all, of the embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present application without creative efforts fall within the scope of protection of the present application.

[0051] The various embodiments of the present application may exist 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 construed as a rigid limitation on the scope of the present application; therefore, it should be considered that the described range description has specifically disclosed all possible sub-ranges and single values within that range; for example, it should be considered that the range description from 1 to 6 has 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., and single numbers within the range, such as 1, 2, 3, 4, 5, and 6, and this applies regardless of the range; in addition, whenever a numerical range is indicated herein, it means including any cited number (fraction or integer) within the indicated range.

[0052] In this document, terms including "comprising" and the like mean "including but not limited to". Relative terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. "And / or" describes the associated relationship of associated objects and indicates that three relationships can exist. For example, A and / or B can mean: A exists alone, A and B exist simultaneously, and B exists alone; where A and B can be singular or plural. "At least one" means one or more, and "multiple" means two or more; "at least one kind", "at least one of the following items (pieces)" or similar expressions refer to any combination of these items, including any combination of single item (piece) or plural items (pieces); for example, "at least one of a, b, or c", or, "at least one of a, b, and c" can both mean: a, b, c, a - b (that is, a and b), a - c, b - c, or a - b - c, where a, b, and c can be single or multiple respectively. "Parts representation method" such as weight parts, mass parts, etc. represents the proportional relationship between each component. In the proportional relationships involved in this document, the parameters that need to be described by proportion should be understood as the antecedents of the proportional formula in the order of description, and the proportional numbers should be understood as the consequents of the proportional formula. For example, if the mass ratio of substance A, substance B, and substance C is 1:2:3, then substance A, substance B, and substance C should correspond one by one with the proportional numbers in the proportional formula in the order of description, that is, the mass of substance A: the mass of substance B: the mass of substance C = 1:2:3.

[0053] Unless otherwise specifically stated, various raw materials, reagents, instruments, equipment, etc. used in this document can be obtained through market purchase or can be prepared by existing methods.

[0054] Figure 1 It is a schematic flow diagram of a method for preparing a large crystal 3A zeolite molecular sieve raw powder according to some embodiments of the present application;

[0055] First aspect, in the embodiments of the present application, a method for preparing large-grained 3A zeolite molecular sieve raw powder is provided, including the following steps:

[0056] S1. Obtain a silica-alumina gel seed;

[0057] S2. Mix a silicon source and an aluminum source to obtain a first mixed slurry;

[0058] Raw materials and ratios

[0059] Silicon source and aluminum source: Mix according to a set silicon-aluminum molar ratio to obtain a first mixed slurry. The molar ratio is controlled between 1.9 and 1.92 to form a stable truncated hexahedron A-type molecular sieve structure.

[0060] S3. Add the silica-alumina gel seed to the first mixed slurry, and then perform first crystallization and second crystallization to obtain a crystallized slurry; and,

[0061] Crystallization process

[0062] Addition of silica-alumina gel seed: Add the silica-alumina gel seed to the mixed slurry to promote the generation of crystal nuclei and the growth of crystals.

[0063] First crystallization and second crystallization: By precisely controlling the crystallization conditions, precise control of the generation of crystal nuclei and the growth of crystals is achieved, the generation of impurity crystals and the agglomeration of twin crystal nuclei are eliminated, and a crystallized slurry is obtained.

[0064] S4. Perform ion exchange on the crystallized slurry to obtain large-grained 3A zeolite molecular sieve raw powder;

[0065] Wherein, the silicon source and the aluminum source are mixed according to a molar ratio of SiO 2 :Al 2 O 3 of 1.9 to 1.92;

[0066] The reaction parameters of the first crystallization include at least one of the following parameters: the temperature of the first crystallization is 70°C to 75°C, and the heat preservation time of the first crystallization is 5 h to 6 h;

[0067] The reaction parameters of the second crystallization include at least one of the following parameters: the temperature of the second crystallization is 90°C to 95°C, and the heat preservation time is 4 h to 4.5 h.

[0068] In the above embodiment, it is controlled that the silicon source and the aluminum source are in accordance with SiO 2 :Al 2 O 3The reason for the molar ratio being 1.9 to 1.92 is that within this range, a stable truncated octahedron A-type zeolite molecular sieve structure can be formed. When the molar ratio exceeds 1.92, impurity crystals are likely to be generated. When the molar ratio is lower than 1.90, the crystallinity of the product is affected. Exemplarily, the molar ratio of the silicon source and the aluminum source according to SiO 2 :Al 2 O 3 can be 1.9, 1.91 or 1.92.

[0069] The reason for controlling the temperature of the first crystallization to be 70°C to 75°C is that within this temperature range, a uniform and stable gel precursor can be formed. Under the action of low-activity crystal seeds, the initial crystal nuclei of 4A zeolite are formed. As time extends, the initial crystal nuclei grow slowly to form uniform and regular crystals. The heat preservation time of the first crystallization is 5h to 6h, enabling the crystal nuclei to have sufficient time to grow, and it can also be adjusted according to the actual crystal growth situation. Exemplarily, the temperature of the first crystallization can be 70°C, 71°C, 72°C, 73°C, 74°C, 75°C.

[0070] The reason for controlling the temperature of the second crystallization to be 90°C to 95°C is that within this temperature range, the driving force for crystal growth can be strengthened, enabling the crystal grain size and crystallinity to be further improved. The heat preservation time is 4h to 4.5h, and the specific time is not limited. Exemplarily, the temperature of the second crystallization can be 90°C, 91°C, 92°C, 93°C, 94°C, 95°C.

[0071] As an optional implementation manner, the aluminum source is selected as sodium aluminate semen leached by the Bayer process, and the silicon source is selected as water glass.

[0072] As an optional implementation manner, ion-exchanging the crystallization slurry to obtain the raw powder of large-grain 3A zeolite molecular sieve specifically includes:

[0073] S41. Separating the solid and liquid of the crystallization slurry to obtain a solid-phase substance;

[0074] S42. Leaching and stirring the solid-phase substance to obtain a second mixed slurry;

[0075] S43. Performing an ion homogenization reaction on the second mixed slurry to obtain a homogenized slurry; and,

[0076] S44. Separating the solid and liquid of the homogenized slurry to obtain the raw powder of large-grain 3A zeolite molecular sieve.

[0077] In the above implementation manner, after the solid-liquid separation of the crystallization slurry, the main component of the solid-phase substance is Na 2 O·Al 2 O 3 ·2SiO 2 ·4.5H2 O, the main components of the filtrate are Al 2 O 3 , SiO2, NaOH and H 2 O; The solid-phase material is leached and stirred to achieve the ion exchange process. The sodium ions in the solid-phase material are exchanged with potassium ions by three times of ion exchange. The components in the obtained second mixed slurry are 2 / 3K 2 O·1 / 3Na 2 O·Al 2 O 3 ·2SiO 2 ·4.5H 2 O; The second mixed slurry is subjected to an ion homogenization reaction, the purpose of which is to ensure that the potassium ion exchange reaches dynamic equilibrium. Finally, the homogenized slurry is separated into solid and liquid to obtain the raw powder of large-crystalline 3A zeolite molecular sieve.

[0078] As an optional implementation manner, the leaching and stirring of the solid-phase material to obtain the second mixed slurry specifically includes:

[0079] S421. Using the first potassium ion solution, the solid-phase material is leached once in sequence;

[0080] S422. Using the second potassium ion solution, the solid-phase material after the first leaching is leached a second time;

[0081] S423. Using the third potassium ion solution, the solid-phase material after the second leaching is slurried and stirred to obtain the second mixed slurry;

[0082] Among them, the concentrations of the first potassium ion solution, the second potassium ion solution and the third potassium ion solution show an increasing trend. The reason is that the sodium ions are smoothly displaced from the molecular sieve pores by the increasing gradient concentration of potassium ions.

[0083] As an optional implementation manner, the mass concentration of the first potassium ion solution is 10 g / L to 20 g / L; Exemplarily, the concentration of the potassium ion solution during the first leaching can be 10 g / L, 12 g / L, 14 g / L, 16 g / L, 18 g / L, or 20 g / L.

[0084] As an optional implementation manner, the mass concentration of the second potassium ion solution is 20 g / L to 40 g / L; Exemplarily, the concentration of the potassium ion solution during the second leaching can be 20 g / L, 22 g / L, 24 g / L, 26 g / L, 28 g / L, 30 g / L, 32 g / L, 34 g / L, 36 g / L, 38 g / L or 40 g / L.

[0085] As an alternative embodiment, the mass concentration of the third potassium ion solution is 40 g / L to 60 g / L; for example, the concentration of the potassium ion solution for beating and washing can be 40 g / L, 42 g / L, 44 g / L, 46 g / L, 48 g / L, 50 g / L, 52 g / L, 54 g / L, 56 g / L, 58 g / L or 60 g / L.

[0086] In the above embodiment, the reason for separately controlling the concentrations of the first potassium ion solution, the second potassium ion solution, and the third potassium ion solution is to achieve efficient utilization of potassium ions and avoid waste.

[0087] As an alternative embodiment, the solid-liquid separation of the crystallization slurry to obtain a solid substance specifically includes:

[0088] S411. Perform solid-liquid separation on the crystallization slurry to obtain solid impurities;

[0089] S412. Beat the solid impurities with hot water to obtain an impurity slurry;

[0090] S413. Perform solid-liquid separation on the impurity slurry to obtain a solid substance.

[0091] In the above embodiment, the reason for beating the solid substance with hot water is to reduce the Na 2 O attached to the zeolite crystals by means of hot water washing.

[0092] As an alternative embodiment, the time of the ion homogenization reaction is 2 h to 4 h.

[0093] In the above embodiment, the reason for controlling the time of the ion homogenization reaction is that the industrial production tank has a large volume and sufficient ion exchange time is required. If the ion homogenization reaction time is longer than 4 h, the time is too long, which will cause the temperature in the tank to decrease and is not conducive to subsequent washing; if the ion homogenization reaction time is shorter than 2 h, the homogenization will be incomplete.

[0094] As an alternative embodiment, the volume addition amount of the silica-alumina gel seed accounts for 3 / 10000 to 10 / 10000 of the total volume of the mixture of the mixed slurry and the silica-alumina gel seed.

[0095] In the above embodiment, the reason for controlling the volume addition amount of the silica-alumina gel seed is to control the number of crystal nuclei formed by the seed. If the seed addition amount exceeds 10 / 10000, more crystal nuclei will be formed, resulting in a smaller crystal size in the end; if the seed addition amount is less than 3 / 10000 of the total volume of the mixture, the number of crystal nuclei formed is too small, which may easily lead to crystal agglomeration and an irregular crystal structure.

[0096] As an optional implementation manner, obtaining the silicon-aluminum gel seed specifically includes:

[0097] S11. Obtaining a seed silicon source and a seed aluminum source;

[0098] S12. Mixing and reacting the seed silicon source and the seed aluminum source to obtain a silicon-aluminum gel seed;

[0099] Among them, the seed aluminum source satisfies at least one of the following conditions: the alumina concentration is 20 g / L to 30 g / L, and the caustic coefficient is 10 to 13;

[0100] The seed silicon source satisfies at least one of the following conditions: the concentration of silicon dioxide is 17% to 20%, and the specific gravity is 1.25 to 1.4;

[0101] The seed silicon source and the seed aluminum source are mixed according to the molar ratio of SiO 2 :Al 2 O 3 of 10 to 13.

[0102] In the above implementation manner, the reason for controlling the alumina concentration in the seed aluminum source to be 20 g / L to 30 g / L is that the alumina concentration within this range can control the activity of the seed. When the alumina concentration exceeds 30 g / L, the seed activity increases, and it is easy for the seed to produce impurity crystals. If it is lower than 20 g / L, the seed activity decreases, and the seed induction becomes weaker. The purpose of controlling the caustic coefficient is to control the molar ratio of Na 2 O to Al 2 O 3 If the caustic coefficient exceeds 13, it is easy to induce impurity crystals. If the caustic coefficient is lower than 10, the seed induction becomes weaker. The reason for controlling the concentration of silicon dioxide in the silicon source is to control the activity of the seed. If the concentration of silicon dioxide is higher than 20%, it is easy to induce impurity crystals. If it is lower than 17%, the seed induction becomes weaker. The reason for controlling the specific gravity is to control the density of water glass. When the specific gravity exceeds 1.4, the density of water glass is too large, and the viscosity is too large, which is not conducive to full mixing reaction. When the specific gravity is lower than 1.25, the density of water glass is too small, and the transportation cost of water glass increases.

[0103] Controlling the seed silicon source and the seed aluminum source to be mixed according to the molar ratio of SiO 2 :Al 2 O 3 of 10 to 13 is to control the selective induction of the seed. If the molar ratio is less than 10, the seed induction becomes weaker. If the molar ratio is greater than 13, it is easy to induce the generation of impurity crystals, resulting in impure crystals in the later stage.

[0104] As an optional implementation manner, mixing and reacting the seed aluminum source and the seed silicon source to obtain a silicon-aluminum gel seed specifically includes:

[0105] S121. Mix the silicon source and the aluminum source, and stir for a first set time to obtain a third mixed slurry;

[0106] S122. Dilute the third mixed slurry by 10 times;

[0107] S123. Stir the diluted third mixed slurry for a second set time to obtain a silicon-aluminum gel seed;

[0108] Among them, the first set time is 0.5 - 1.5 h;

[0109] The second set time is 0.5 - 1.5 h.

[0110] In the above embodiment, the purpose of the first stirring is to promote the full reaction of the silicon source and the aluminum source to form seeds; the purpose of dilution is to reduce the activity of the seeds by reducing the concentration of the seeds, and the purpose of the second stirring is to make the silicon-aluminum gel seeds evenly diluted in water.

[0111] In the embodiment of the present application, a preparation method of large-grained 3A zeolite molecular sieve powder is provided, which has the following technical advantages:

[0112] Precise control: By precisely controlling the silicon-aluminum molar ratio and the crystallization process, precise regulation of the structure and performance of the molecular sieve is achieved.

[0113] High performance: The prepared 3A molecular sieve has excellent particle size, bulk specific gravity and water adsorption performance, greatly improving the loading rate and utilization rate of the equipment.

[0114] Wide application: It is applicable to multiple fields such as gas separation, liquid dehydration, catalysis, etc., and has a broad market prospect.

[0115] In the second aspect, based on a general inventive concept, in the embodiment of the present application, a large-grained 3A zeolite molecular sieve powder is provided, which is prepared by using the preparation method of the large-grained 3A zeolite molecular sieve powder described in any one of the first aspect embodiments.

[0116] The large-grained 3A zeolite molecular sieve powder is realized based on the above preparation method of the large-grained 3A zeolite molecular sieve powder. The specific steps of the preparation method of the large-grained 3A zeolite molecular sieve powder can refer to the above embodiments. Since the large-grained 3A zeolite molecular sieve powder adopts some or all of the technical solutions of the above embodiments, it at least has all the beneficial effects brought by the technical solutions of the above embodiments, and will not be elaborated here one by one.

[0117] The present application will be further elaborated below in conjunction with specific embodiments. For the experimental methods without specific conditions noted in the following embodiments, they are generally determined in accordance with national standards / industry standards; if there are no corresponding national standards / industry standards, they are carried out in accordance with general international standards, conventional conditions or the conditions recommended by the manufacturer.

[0118] Example 1

[0119] This example provides a method for preparing a large-grained 3A zeolite molecular sieve raw powder, including the following steps:

[0120] S1. Obtain a silica-alumina gel seed;

[0121] Obtain a seed silica source and a seed alumina source, wherein the concentration of silicon dioxide in the seed silica source is 17%, and the specific gravity is 1.25; the concentration of alumina in the seed alumina source is 24 g / L, and the caustic coefficient is 11;

[0122] Mix the seed silica source and the seed alumina source according to the molar ratio of SiO 2 :Al 2 O 3 of 10, stir for 1 h and then dilute ten times, and then stir for 1 h to obtain a silica-alumina gel seed;

[0123] S2. Respectively use the sodium aluminate mother liquor leached by the Bayer process of Guinea bauxite and water glass as the alumina source and the silica source, and add them to the synthesis tank according to the molar ratio of SiO 2 / Al 2 O 3 of 1.9, stir and wash for synthesis for 20 minutes to obtain a first mixed slurry;

[0124] S3. Then pump the first mixed slurry into a mixing tank, add a silica-alumina gel seed thereto, and the added volume of the seed accounts for 3 / 10000 of the mixture of the seed and the first mixed slurry. Pump the mixed slurry into a crystallization tank for crystallization reaction to obtain a crystallized slurry; the crystallization temperature in the first stage is 70 °C, and the heat preservation time is 5 h; the crystallization temperature in the second stage is 90 °C, and the heat preservation time is 4 h.

[0125] S4. Filter and wash the crystallized slurry through an A-tape filter to perform a first solid-liquid separation. After separating the solid-phase substance, add it to hot water for pulping, and the pulped slurry enters the mother liquor vacuum adsorption area of the B-tape filter for a second mother liquor separation to obtain a solid-phase substance.

[0126] Perform potassium and sodium ion exchange on the solid-phase substance by performing a first washing and a second washing with a potassium chloride solution in the first washing vacuum adsorption area of the B-tape filter and the second washing vacuum adsorption area of the B-tape filter respectively. The concentration of the potassium chloride solution during the first washing is 15 g / L, and the concentration of the potassium chloride solution during the second washing is 30 g / L;

[0127] The solid phase material after secondary rinsing is added to a 50 g / L potassium chloride solution for pulping and stirring washing to obtain a second mixed pulp; then the second mixed pulp is pumped into a pulp homogenization tank for potassium and sodium ion homogenization reaction for 2 h.

[0128] The homogenized pulp is washed and separated by a vertical filter press, dried by a flash dryer to obtain the raw powder of large crystal 3A zeolite molecular sieve, and the electron micrograph obtained after electron microscope scanning is as Figure 2 shown, and it can be clearly seen from Figure 2 that the molecular sieve structure is a cubic structure.

[0129] Example 2

[0130] This example provides a method for preparing the raw powder of large crystal 3A zeolite molecular sieve, including the following steps:

[0131] S1. Obtain a silica-alumina gel seed;

[0132] Obtain a seed silicon source and a seed aluminum source, where the concentration of silicon dioxide in the seed silicon source is 20%, and the specific gravity is 1.4; the concentration of aluminum oxide in the seed aluminum source is 20 g / L, and the caustic coefficient is 10;

[0133] Mix the seed silicon source and the seed aluminum source according to the molar ratio of SiO 2 :Al 2 O 3 of 10, stir for 1 h, then dilute ten times, and then stir for 1 h to obtain a silica-alumina gel seed;

[0134] S2. Respectively use the sodium aluminate mother liquor obtained by the Bayer process of Guinea bauxite and water glass as the aluminum source and the silicon source, and add them to the synthesis tank according to the molar ratio of SiO 2 / Al 2 O 3 of 1.91, stir and wash for 20 minutes to obtain a first mixed pulp;

[0135] S3. Then pump the first mixed pulp into a mixing tank, add a silica-alumina gel seed to it, the added volume of the seed accounts for 6 / 10000 of the mixture of the seed and the first mixed pulp, and pump the mixed slurry into a crystallization tank for crystallization reaction to obtain a crystallized pulp; among them, the temperature of the first-stage crystallization is 73 °C, and the holding time is 5.5 hours; the temperature of the second-stage crystallization is 93 °C, and the holding time is 4.5 hours.

[0136] S4. The crystallized pulp is washed by an A-belt filter for primary solid-liquid separation. After separating the solid phase material, it is added to hot water for pulping, and the pulped slurry enters the mother liquor vacuum adsorption area of the B-belt filter for secondary mother liquor separation to obtain the solid phase material.

[0137] The solid phase material is subjected to primary leaching and secondary leaching with potassium chloride solution in the primary leaching vacuum adsorption area of the B-tape filter and the secondary leaching vacuum adsorption area of the B-tape filter respectively for potassium and sodium ion exchange. The concentration of potassium chloride solution during primary leaching is 18 g / L, and the concentration of potassium chloride solution during secondary leaching is 35 g / L;

[0138] The solid phase material after secondary leaching is added with 52 g / L potassium chloride solution for pulping and stirring washing to obtain a second mixed slurry; then the second mixed slurry is pumped into a slurry homogenization tank for potassium and sodium ion homogenization reaction for 3 h.

[0139] The homogenized slurry is washed and separated by a vertical filter press and dried by a flash dryer to obtain the raw powder of large crystal 3A zeolite molecular sieve.

[0140] Example 3

[0141] This example provides a method for preparing the raw powder of large crystal 3A zeolite molecular sieve, which includes the following steps:

[0142] S1, obtaining a silica-alumina gel seed;

[0143] Obtaining a seed silicon source and a seed aluminum source, wherein the concentration of silicon dioxide in the seed silicon source is 18%, and the specific gravity is 1.31; the concentration of aluminum oxide in the seed aluminum source is 27 g / L, and the caustic coefficient is 13;

[0144] Mix the seed silicon source and the seed aluminum source according to the molar ratio of SiO 2 :Al 2 O 3 of 12, stir for 1 h and then dilute ten times, and then stir for 1 h to obtain a silica-alumina gel seed;

[0145] S2, using the sodium aluminate mother liquor obtained by the Bayer process of Guinea bauxite and water glass as the aluminum source and the silicon source respectively, adding them to the synthesis tank according to the molar ratio of SiO 2 / Al 2 O 3 of 1.92, stir and synthesize for 20 minutes to obtain a first mixed slurry;

[0146] S3, then pump the first mixed slurry into a mixing tank, add the silica-alumina gel seed to it, the added volume of the seed accounts for 8 / 10000 of the mixture of the seed and the first mixed slurry, and pump the mixed slurry into a crystallization tank for crystallization reaction to obtain a crystallized slurry; the temperature of the first-stage crystallization is 70 °C, and the heat preservation time is 6 h; the temperature of the second-stage crystallization is 95 °C, and the heat preservation time is 4.2 h.

[0147] S4. The crystallized slurry is subjected to primary solid-liquid separation by leaching through an A-tape filter. After separating the solid phase material, it is slurried in hot water. After slurrying, the slurry enters the mother liquor vacuum adsorption area of a B-tape filter for secondary mother liquor separation to obtain the solid phase material.

[0148] The solid phase material is subjected to primary leaching and secondary leaching with potassium chloride solution in the primary leaching vacuum adsorption area and the secondary leaching vacuum adsorption area of the B-tape filter respectively for potassium and sodium ion exchange. The concentration of the potassium chloride solution during primary leaching is 14 g / L, and the concentration of the potassium chloride solution during secondary leaching is 37 g / L.

[0149] The solid phase material after secondary leaching is added to a 55 g / L potassium chloride solution for slurrying and stirring washing to obtain a second mixed slurry. Then the second mixed slurry is pumped into a slurry homogenization tank for potassium and sodium ion homogenization reaction for 4 h.

[0150] The homogenized slurry is washed and separated by a vertical filter press and dried by a flash dryer to obtain the raw powder of large crystal 3A zeolite molecular sieve.

[0151] Example 4

[0152] This example provides a method for preparing the raw powder of large crystal 3A zeolite molecular sieve, including the following steps:

[0153] S1. Obtain a silica-alumina gel seed;

[0154] Obtain a seed silicon source and a seed aluminum source. The concentration of silicon dioxide in the seed silicon source is 20%, and the specific gravity is 1.4. The concentration of alumina in the seed aluminum source is 24 g / L, and the caustic coefficient is 11.

[0155] Mix the seed silicon source and the seed aluminum source according to the molar ratio of SiO 2 :Al 2 O 3 of 11, stir for 1 h, then dilute ten times, and stir for another 1 h to obtain a silica-alumina gel seed;

[0156] S2. Respectively use the sodium aluminate mother liquor obtained by the Bayer process of Guinea bauxite and water glass as the aluminum source and the silicon source, and add them to the synthesis tank according to the molar ratio of SiO 2 / Al 2 O 3 of 1.91, stir and wash for synthesis for 20 minutes to obtain a first mixed slurry;

[0157] S3. Then pump the first mixture slurry into a mixing tank, add a silica-alumina gel seed thereto, with the added volume of the seed accounting for 10 / 10000 of the mixture of the seed and the first mixture slurry. Pump the mixed slurry into a crystallization tank for crystallization reaction to obtain a crystallized slurry. Among them, the temperature for the first-stage crystallization is 74 °C and the heat preservation time is 5 hours; the temperature for the second-stage crystallization is 94 °C and the heat preservation time is 4.4 hours.

[0158] S4. Subject the crystallized slurry to primary solid-liquid separation by leaching with an A-tape filter. After separating the solid phase material, add it to hot water for pulping. After pulping, the slurry enters the mother liquor vacuum adsorption area of a B-tape filter for secondary mother liquor separation to obtain the solid phase material.

[0159] Perform primary leaching and secondary leaching on the solid phase material with potassium chloride solution in the primary leaching vacuum adsorption area and the secondary leaching vacuum adsorption area of the B-tape filter respectively for potassium and sodium ion exchange. Among them, the concentration of the potassium chloride solution during primary leaching is 12 g / L, and the concentration of the potassium chloride solution during secondary leaching is 39 g / L;

[0160] Add the solid phase material after secondary leaching to a 56 g / L potassium chloride solution for pulping and stirring and washing to obtain a second mixture slurry. Then pump the second mixture slurry into a slurry homogenization tank for potassium and sodium ion homogenization reaction for 3 h.

[0161] The homogenized slurry is washed and separated by a vertical filter press and dried by a flash dryer to obtain the raw powder of large crystal 3A zeolite molecular sieve.

[0162] Example 5

[0163] This example provides a method for preparing the raw powder of large crystal 3A zeolite molecular sieve, including the following steps:

[0164] S1. Obtain a silica-alumina gel seed;

[0165] Obtain a seed silicon source and a seed aluminum source, where the concentration of silicon dioxide in the seed silicon source is 17% and the specific gravity is 1.25; the concentration of aluminum oxide in the seed aluminum source is 30 g / L and the caustic coefficient is 13;

[0166] Mix the seed silicon source and the seed aluminum source according to the molar ratio of SiO 2 :Al 2 O 3 of 13, stir for 1 h and then dilute ten times, and then stir for 1 h to obtain a silica-alumina gel seed;

[0167] S2. Respectively use the sodium aluminate mother liquor obtained by the Bayer digestion of Guinea bauxite and water glass as the aluminum source and the silicon source, according to SiO 2 / Al 2 O 3Add to the synthesis tank at a molar ratio of 1.9, stir and wash for synthesis for 20 minutes to obtain the first mixed slurry;

[0168] S3. Then pump the first mixed slurry into a mixing tank, add a silica-alumina gel seed thereto, the added volume of the seed accounting for 5 / 10,000 of the mixture of the seed and the first mixed slurry, and pump the mixed slurry into a crystallization tank for crystallization reaction to obtain a crystallized slurry; wherein the primary crystallization temperature is 70 °C and the heat preservation time is 5 hours; the secondary crystallization temperature is 90 °C and the heat preservation time is 4.5 hours.

[0169] S4. Filter and wash the crystallized slurry through an A-tape filter to perform primary solid-liquid separation. After separating the solid phase material, add it to hot water for pulping, and after pulping, the slurry enters the mother liquor vacuum adsorption area of a B-tape filter for secondary mother liquor separation to obtain the solid phase material.

[0170] Perform primary washing and secondary washing on the solid phase material with potassium chloride solution in the primary washing vacuum adsorption area and the secondary washing vacuum adsorption area of the B-tape filter respectively for potassium and sodium ion exchange, wherein the concentration of the potassium chloride solution during primary washing is 10 g / L, and the concentration of the potassium chloride solution during secondary washing is 35 g / L;

[0171] Add the solid phase material after secondary washing to a 50 g / L potassium chloride solution for pulping and stirring and washing to obtain a second mixed slurry; then pump the second mixed slurry into a slurry homogenization tank for potassium and sodium ion homogenization reaction for 2 h.

[0172] The homogenized slurry is washed and separated by a vertical filter press and dried by a flash dryer to obtain the raw powder of large crystal 3A zeolite molecular sieve.

[0173] Comparative Example 1

[0174] This comparative example provides a method for preparing the raw powder of large crystal 3A zeolite molecular sieve, including the following steps:

[0175] S1. Obtain a silica-alumina gel seed;

[0176] Obtain a seed silicon source and a seed aluminum source, wherein the concentration of silicon dioxide in the seed silicon source is 23%, and the specific gravity is 1.25; the concentration of aluminum oxide in the seed aluminum source is 24 g / L, and the caustic coefficient is 15;

[0177] Mix the seed silicon source and the seed aluminum source according to a molar ratio of SiO 2 :Al 2 O 3 of 10, stir for 1 h and then dilute ten times, and then stir for 1 h to obtain a silica-alumina gel seed;

[0178] S2. Respectively use the sodium aluminate semen obtained by the Bayer process of Guinea bauxite and water glass as the aluminum source and the silicon source, according to SiO2 / Al 2 O 3 Add to the synthesis tank at a molar ratio of 1.9, stir and wash for synthesis for 20 minutes to obtain the first mixed slurry;

[0179] S3. Then pump the first mixed slurry into the mixing tank, add a seed crystal of silica-alumina gel to it, and the added volume of the seed crystal accounts for 3 / 10,000 of the mixture of the seed crystal and the first mixed slurry. Pump the mixed slurry into the crystallization tank for crystallization reaction to obtain a crystallized slurry; among them, the temperature of the first-stage crystallization is 70°C and the heat preservation time is 5 hours; the temperature of the second-stage crystallization is 90°C and the heat preservation time is 4 hours.

[0180] S4. Filter and wash the crystallized slurry through an A-belt filter for primary solid-liquid separation. After separating the solid phase material, add it to hot water for pulping. After pulping, the slurry enters the mother liquor vacuum adsorption area of the B-belt filter for secondary mother liquor separation to obtain the solid phase material.

[0181] Perform primary washing and secondary washing on the solid phase material with potassium chloride solution in the primary washing vacuum adsorption area and the secondary washing vacuum adsorption area of the B-belt filter respectively for potassium and sodium ion exchange. Among them, the concentration of the potassium chloride solution during the primary washing is 15 g / L, and the concentration of the potassium chloride solution during the secondary washing is 30 g / L;

[0182] Add the solid phase material after secondary washing to 50 g / L potassium chloride solution for pulping and stirring to obtain the second mixed slurry; then pump the second mixed slurry into the slurry homogenization tank for potassium and sodium ion homogenization reaction for 2 h.

[0183] The homogenized slurry is washed and separated by a vertical filter press and dried by a flash dryer to obtain the molecular sieve raw powder.

[0184] Comparative Example 2

[0185] This comparative example provides a method for preparing a large-grain 3A zeolite molecular sieve raw powder, including the following steps:

[0186] S1. Obtain a silica-alumina gel seed crystal;

[0187] Obtain the seed crystal silicon source and the seed crystal aluminum source. Among them, the concentration of silicon dioxide in the seed crystal silicon source is 20%, and the specific gravity is 1.4; the concentration of aluminum oxide in the seed crystal aluminum source is 20 g / L, and the caustic coefficient is 10;

[0188] Mix the seed crystal silicon source and the seed crystal aluminum source according to the molar ratio of SiO 2 :Al 2 O 3 of 10, stir for 1 h and then dilute ten times, and then stir for 1 h to obtain the silica-alumina gel seed crystal;

[0189] S2, respectively use sodium aluminate solution obtained by the Bayer process of Guinea bauxite and sodium silicate as the aluminum source and silicon source, and add them to the synthesis tank according to the molar ratio of SiO 2 / Al 2 O 3 of 1.80, stir and wash for 20 minutes to obtain the first mixed slurry;

[0190] S3, then pump the first mixed slurry into the mixing tank, add a silicon-aluminum gel seed crystal to it, and the added volume of the seed crystal accounts for 6 / 10,000 of the mixture of the seed crystal and the first mixed slurry. Pump the mixed slurry into the crystallization tank for crystallization reaction to obtain a crystallized slurry; among them, the first-stage crystallization temperature is 73 °C and the heat preservation time is 5.5 hours; the second-stage crystallization temperature is 93 °C and the heat preservation time is 4.5 hours.

[0191] S4, filter and wash the crystallized slurry through an A-tape filter to perform primary solid-liquid separation. After separating the solid-phase substance, add it to hot water for pulping. After pulping, the slurry enters the mother liquor vacuum adsorption area of the B-tape filter for secondary mother liquor separation to obtain the solid-phase substance.

[0192] Perform primary washing and secondary washing with potassium chloride solution in the primary washing vacuum adsorption area and the secondary washing vacuum adsorption area of the B-tape filter for the solid-phase substance to perform potassium and sodium ion exchange. Among them, the concentration of the potassium chloride solution during the primary washing is 18 g / L, and the concentration of the potassium chloride solution during the secondary washing is 35 g / L;

[0193] Add the solid-phase substance after secondary washing to a 52 g / L potassium chloride solution for pulping and stirring to obtain the second mixed slurry; then pump the second mixed slurry into the slurry homogenization tank for potassium and sodium ion homogenization reaction for 3 h.

[0194] The homogenized slurry is washed and separated by a vertical filter press and dried by a flash dryer to obtain the raw powder of large-crystalline 3A zeolite molecular sieve.

[0195] Comparative Example 3

[0196] This comparative example provides a method for preparing the raw powder of large-crystalline 3A zeolite molecular sieve, including the following steps:

[0197] S1, obtain a silicon-aluminum gel seed crystal;

[0198] Obtain the seed crystal silicon source and the seed crystal aluminum source, where the concentration of silicon dioxide in the seed crystal silicon source is 18%, and the specific gravity is 1.31; the concentration of aluminum oxide in the seed crystal aluminum source is 27 g / L, and the caustic coefficient is 13;

[0199] Mix the seed crystal silicon source and the seed crystal aluminum source according to SiO 2 :Al 2 O 3Mix them in a molar ratio of 12, stir for 1 h, then dilute tenfold, and stir for another 1 h to obtain a silica-alumina gel seed;

[0200] S2. Respectively, use the sodium aluminate mother liquor obtained by the Bayer process of Guinea bauxite and water glass as the aluminum source and the silicon source. According to the SiO 2 / Al 2 O 3 molar ratio of 1.92, add them to the synthesis tank, stir and wash for 20 minutes to obtain the first mixed slurry;

[0201] S3. Then pump the first mixed slurry into the mixing tank, add the silica-alumina gel seed to it. The added volume of the seed accounts for 20 / 10000 of the mixture of the seed and the first mixed slurry. Pump the mixed slurry into the crystallization tank for crystallization reaction to obtain a crystallized slurry. Among them, the temperature of the first-stage crystallization is 80 °C and the heat preservation time is 6.5 hours; the temperature of the second-stage crystallization is 100 °C and the heat preservation time is 4.2 hours.

[0202] S4. Wash the crystallized slurry through an A-belt filter for the first solid-liquid separation. After separating the solid phase material, add it to hot water for pulping. After pulping, the slurry enters the mother liquor vacuum adsorption area of the B-belt filter for the second mother liquor separation to obtain the solid phase material.

[0203] Perform potassium and sodium ion exchange on the solid phase material by using potassium chloride solution for the first washing and the second washing in the first washing vacuum adsorption area and the second washing vacuum adsorption area of the B-belt filter respectively. Among them, the concentration of the potassium chloride solution during the first washing is 14 g / L, and the concentration of the potassium chloride solution during the second washing is 37 g / L;

[0204] Add the solid phase material after the second washing to a 55 g / L potassium chloride solution for pulping and stirring to obtain the second mixed slurry; then pump the second mixed slurry into the slurry homogenization tank for potassium and sodium ion homogenization reaction for 4 h.

[0205] The homogenized slurry is washed and separated by a vertical filter press and dried by a flash dryer to obtain the raw powder of large crystal 3A zeolite molecular sieve.

[0206] Comparative Example 4

[0207] This comparative example provides a method for preparing the raw powder of large crystal 3A zeolite molecular sieve, including the following steps:

[0208] S1. Obtain a silica-alumina gel seed;

[0209] Obtain the seed silicon source and the seed aluminum source. Among them, the concentration of silicon dioxide in the seed silicon source is 20%, and the specific gravity is 1.4; the concentration of aluminum oxide in the seed aluminum source is 24 g / L, and the caustic coefficient is 11;

[0210] Mix the seed silicon source and the seed aluminum source according to SiO2 : Al 2 O 3 were mixed at a molar ratio of 13, stirred for 1 h, diluted tenfold, and then stirred for another 1 h to obtain a silica-alumina gel seed;

[0211] S2, using the sodium aluminate semen leached from Guinea bauxite by the Bayer process and sodium silicate as the aluminum source and silicon source respectively, according to SiO 2 / Al 2 O 3 The molar ratio of 1.91 was added to the synthesis tank, stirred and washed for 20 minutes to obtain the first mixed slurry;

[0212] S3, then the first mixed slurry was pumped into the mixing tank, and a silica-alumina gel seed was added thereto. The added volume of the seed accounted for 10 / 10000 of the mixture of the seed and the first mixed slurry. The mixed slurry was pumped into the crystallization tank for crystallization reaction to obtain a crystallized slurry; the crystallization temperature of the first stage was 74 °C and the holding time was 5 hours; the crystallization temperature of the second stage was 94 °C and the holding time was 4.4 hours.

[0213] S4, the crystallized slurry was filtered and washed through an A-tape filter to perform a primary solid-liquid separation. After separating the solid phase material, it was added to hot water for pulping, and after pulping, the slurry entered the mother liquor vacuum adsorption area of the B-tape filter for a secondary mother liquor separation to obtain the solid phase material.

[0214] The solid phase material was subjected to primary washing and secondary washing with potassium chloride solution in the primary washing vacuum adsorption area and the secondary washing vacuum adsorption area of the B-tape filter respectively for potassium and sodium ion exchange. The concentration of the potassium chloride solution during the primary washing was 25 g / L, and the concentration of the potassium chloride solution during the secondary washing was 47 g / L;

[0215] The solid phase material after the secondary washing was added to a 65 g / L potassium chloride solution for pulping and stirring to obtain a second mixed slurry; then the second mixed slurry was pumped into the slurry homogenization tank for potassium and sodium ion homogenization reaction for 3 h.

[0216] The homogenized slurry was washed and separated by a vertical filter press and dried by a flash dryer to obtain the raw powder of large crystal 3A zeolite molecular sieve.

[0217] The particle size, bulk specific gravity and static water adsorption of the raw powder of 3A zeolite molecular sieve provided in Examples 1-5 and Comparative Examples 1-4 were detected, and the results are shown in Table 1 below:

[0218] Table 1 Performance test results of the raw powder of 3A zeolite molecular sieve provided in Examples 1-5 and Comparative Examples 1-4

[0219] Particle size D50 (μm) Bulk specific gravity (g / m) Static water adsorption (%) Example 1 5.5 0.812 25.91 Example 2 6.0 0.817 26.12 Example 3 6.4 0.824 26.24 Example 4 6.2 0.819 26.08 Example 5 5.6 0.796 25.84 Comparative Example 1 5.3 0.792 24.42 Comparative Example 2 4.9 0.786 24.37 Comparative Example 3 4.8 0.762 25.54 Comparative Example 4 5.2 0.792 24.30

[0220] As can be seen from the data in the above table, the large-grained 3A zeolite molecular sieve raw powder prepared by the preparation methods provided in Examples 1 to 4 basically all meet the requirements that the particle size D50 is greater than 5 μm and the bulk specific gravity is greater than 0.8 g / m. At the same time, through static water adsorption experiments on it, it is found that at 25 °C and 50% relative humidity, the saturated water adsorption is greater than 25.5%. Although the bulk specific gravity of the molecular sieve raw powder in Example 5 is 0.796 g / m, slightly lower than 0.8 g / m, its particle size D50 and static water adsorption both meet the requirements. In addition, the bulk specific gravities of the molecular sieve raw powders prepared in Comparative Examples 1 to 4 are all less than 0.8 g / m. Moreover, the particle size D50 of the molecular sieve raw powders prepared in Comparative Examples 2 and 3 are both lower than 5.0 μm, with the lowest being 4.8 μm. For the static water adsorption results, only the molecular sieve raw powder prepared in Comparative Example 3 has a saturated water adsorption greater than 25.54% at 25 °C and 50% relative humidity.

[0221] In summary, the present application provides a preparation method for a large-grained 3A zeolite molecular sieve raw powder. In this method, the silicon source and the aluminum source are mixed according to a set silicon-aluminum molar ratio to obtain a first mixed slurry, and the molar ratio is controlled to be 1.9 to 1.92 to form a stable truncated hexahedron A-type molecular sieve structure. The silicon-aluminum gel seeds are added to the mixed slurry, and then first crystallization and second crystallization are carried out to achieve precise control over the generation of crystal nuclei and crystal growth, eliminate the generation of impurity crystals and the agglomeration of twin crystal nuclei, and obtain a crystallized slurry. After the crystallized slurry is subjected to solid-liquid separation, the main component of the solid phase is Na 2 O·Al 2 O 3 ·2SiO 2 ·4.5H 2 O, and the main components of the filtrate are Al 2 O 3 、SiO 2 、NaOH and H 2 O; The solid phase is subjected to leaching and stirring washing to achieve the ion exchange process. The sodium ions in the solid phase are exchanged with potassium ions by three times of ion exchange, and the component in the obtained second mixed slurry is 2 / 3K 2 O·1 / 3Na 2 O·Al 2 O 3 ·2SiO 2 ·4.5H 2 O; The second mixed slurry is subjected to ion homogenization reaction, the purpose of which is to ensure that the potassium ion exchange reaches dynamic equilibrium. Finally, the homogenized slurry is subjected to solid-liquid separation to obtain the large-grained 3A zeolite molecular sieve raw powder.

[0222] The particle size of the 3A molecular sieve prepared by this method is 5-8 microns, the bulk specific gravity is greater than 0.8 g / ml, the saturated water adsorption is greater than 25.5% at 25 °C and 50% relative humidity, the water adsorption is also greatly improved, significantly higher than the level of the 3A molecular sieve prepared by the prior art, and the packing rate and utilization rate of the 3A molecular sieve equipment are greatly improved.

[0223] The above are only specific embodiments of the present application, enabling those skilled in the art to understand or implement the present application. Various modifications to these embodiments will be obvious to those skilled in the art. The general principles defined in the present application 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 these embodiments shown in the present application, but will conform to the widest scope consistent with the principles and novel features claimed in the present application.

Claims

1. A method for preparing large-grain 3A zeolite molecular sieve raw powder, characterized in that: The following steps are involved: Obtaining silica-alumina gel seed crystals; Mixing a silicon source and an aluminum source to obtain a first mixed slurry; adding the silica-alumina gel seed crystals to the first mixed slurry to perform a first crystallization and a second crystallization to obtain a crystallized slurry; and, The crystallized slurry is subjected to ion exchange to obtain large-grain 3A zeolite molecular sieve raw powder; Wherein, the molar ratio of SiO2 of the silicon source and Al2O3 of the aluminum source is SiO2:Al2O3=1.9-1.92; The reaction parameters of the first crystallization include at least one of the following parameters: the temperature of the first crystallization is 70° C. to 75° C., and the holding time of the first crystallization is 5 h to 6 h; The reaction parameters of the second crystallization include at least one of the following parameters: the temperature of the second crystallization is 90° C. to 95° C., and the insulation time is 4 h to 4.5 h.

2. The preparation method according to claim 1, wherein the crystallized slurry is subjected to ion exchange to obtain large-grained 3A zeolite molecular sieve raw powder, specifically comprising: Performing solid-liquid separation on the crystallized slurry to obtain a solid phase material; The solid phase material is eluted and stirred to obtain a second mixed slurry; The second mixed slurry is subjected to an ion homogenization reaction to obtain a homogenized slurry; as well as, The homogenized slurry is subjected to solid-liquid separation to obtain large-grain 3A zeolite molecular sieve raw powder.

3. The preparation method according to claim 2, wherein the solid phase material is eluted and stirred to obtain a second mixed slurry, specifically comprising: Using a first potassium ion solution, the solid phase material is sequentially eluted once; Using a second potassium ion solution, washing the solid phase material after the first washing for a second time; Using a third potassium ion solution, beating and stirring the solid phase material after the second elution to obtain a second mixed slurry; Among them, the concentrations of the first potassium ion solution, the second potassium ion solution and the third potassium ion solution are increasing.

4. The preparation method according to claim 3, wherein the mass concentration of the first potassium ion solution is 10 g / L to 20 g / L; and / or The mass concentration of the second potassium ion solution is 20 g / L to 40 g / L; and / or The mass concentration of the third potassium ion solution is 40 g / L to 60 g / L.

5. The preparation method according to claim 2, wherein the crystallization slurry is subjected to solid-liquid separation to obtain a solid phase material, specifically comprising: Performing solid-liquid separation on the crystallized slurry to obtain solid impurities; The solid impurities are slurried with hot water to obtain an impurity slurry; The impurity slurry is subjected to solid-liquid separation to obtain a solid phase substance.

6. The preparation method according to claim 2, wherein the time of the ion homogenization reaction is 2 h to 4 h.

7. The preparation method according to claim 1, wherein the volume of the silica-alumina gel seed crystals is 3 / 10000 to 10 / 10000 of the total volume of the mixture of the mixed slurry and the silica-alumina gel seed crystals.

8. The preparation method according to claim 1, wherein obtaining the silica-alumina gel seed crystals comprises: Obtaining a seed silicon source and a seed aluminum source; The seed silicon source and the seed aluminum source are mixed and reacted to obtain a silica-alumina gel seed crystal; Wherein, the seed aluminum source satisfies at least one of the following conditions: the aluminum oxide concentration is 20-30 g / L, and the caustic coefficient is 10-13; The seed silicon source satisfies at least one of the following conditions: the concentration of silicon dioxide is 17% to 20%, and the specific gravity is 1.25 to 1.4; The molar ratio of SiO2 of the seed silicon source to Al2O3 of the seed aluminum source is SiO2:Al2O3=10-13.

9. The preparation method according to claim 8, wherein the seed aluminum source and the seed silicon source are mixed and reacted to obtain alumina-silica gel seed crystals, specifically comprising: Mixing the silicon source and the aluminum source, and stirring for a first set time to obtain a third mixed slurry; Diluting the third mixed slurry by 10 times; Stirring the diluted third mixed slurry for a second set time to obtain silica-alumina gel seed crystals; Wherein, the first setting time is 0.5 to 1.5 hours; The second set time is 0.5 to 1.5 hours.

10. A large-crystal 3A zeolite molecular sieve raw powder, prepared by the large-crystal 3A zeolite molecular sieve raw powder preparation method according to any one of claims 1 to 9.

Images