A preparation method of zinc-added 4A zeolite molecular sieve

Abstract

The present application relates to the technical field of molecular sieve preparation, and in particular to a method for preparing zinc-added 4A zeolite molecular sieve; the method comprises: slurrying and mixing a sodium aluminate solution and a water glass solution, and then performing a first crystallization to obtain an initial crystallization slurry; adding a sodium zincate solution to the initial crystallization slurry, and performing a second crystallization, and then separating, washing and drying to obtain a 4A zeolite molecular sieve product; wherein, the time of the first crystallization is 0.2h to 0.8h; the content of zinc oxide in the sodium zincate solution is 60g / L to 180g / L; in the existing process of synthesizing 4A zeolite from sodium aluminate solution and water glass solution, by adding the sodium zincate solution at the initial crystallization stage, a 4A zeolite product with new functionalization can be produced.

Description

Technical Field

[0001] The present application relates to the technical field of molecular sieve preparation, and in particular to a method for preparing zinc-added 4A zeolite molecular sieve. Background Art

[0002] Zeolite is a type of aluminosilicate crystal that forms different crystal structures based on the arrangement of silicon-oxygen tetrahedra and aluminum-oxygen tetrahedra, including types A, X, and Y. Due to their regular spatial network structure, good stability, and adjustable pore structure, zeolite molecular sieves are widely used as adsorbents and catalyst materials in petroleum processing, the chemical industry, the metallurgical industry, the building materials industry, the environmental protection industry, and other high-tech fields. Among them, type A zeolite molecular sieve has a tetragonal structure similar to sodium chloride. Its chemical formula is Na2O·Al2O3·2SiO2·4.5H2O, and its internal pore diameter is 4.2 angstroms, hence its abbreviation 4A zeolite. Due to its tetragonal structure similar to sodium chloride, type 4A zeolite has many unique properties, such as ion exchange performance. Each oxygen atom in the 4A zeolite framework is shared by two adjacent tetrahedra, making this structure suitable for accommodating internal pores for substances such as cations and water molecules. These cations and water molecules have high mobility, allowing for cation exchange and reversible dehydration.

[0003] PVC stands for polyvinyl chloride. Products made from it are called PVC plastics. PVC plastics, along with steel, wood, and cement, are considered one of the four fundamental building materials. They are widely used in industry, agriculture, construction, chemicals, electronics, machinery, and everyday life. They have become a pillar of national economic development and one of the world's top five most common plastics. PVC plastics are made from PVC resin, a white granular material that offers advantages such as good chemical stability, high mechanical properties, excellent electrical insulation, flame retardancy, and low cost. However, they also suffer from poor thermal stability, a limited operating temperature, the brittleness of rigid products, poor cold resistance, and susceptibility to light and heat degradation. During PVC processing, PVC plastic can only be formed at temperatures above 160°C. It begins to decompose at temperatures between 120°C and 130°C, releasing HCl gas, which catalyzes the degradation of PVC. To prevent thermal degradation during processing and use, additives called heat stabilizers are added. The zeolites that can be used as heat stabilizers include A-type zeolite, P-type zeolite, X-type zeolite and Y-type zeolite. However, in terms of usage effect and cost-effectiveness, since 4A zeolite has the ability to absorb HCl, using 4A zeolite as a PVC heat stabilizer can improve the heat stabilization effect of calcium and zinc composite stabilizers, which makes A-type zeolite more suitable for calcium and zinc composite stabilizers. The heat stabilizer obtained by compounding and processing 4A zeolite with salts such as calcium stearate and zinc through a special process is currently recognized as the only green heat stabilizer in the world that can be used in non-toxic PVC formulations. The thermal stability of 4A zeolite is due to its alkalinity and the presence of numerous cavities that can absorb hydrogen chloride released by PVC degradation. Zeolite also has a certain flame retardant effect on PVC: zeolite loses water (adherent water, structural water) when heated, which not only removes some heat but also dilutes combustible gases, thereby providing a flame retardant effect. In the PVC / zeolite system, the surface of the carbon layer of the combustion residue is covered with zeolite, which can provide a good thermal insulation shield. At the same time, the interior of the carbon layer in the PVC / zeolite system is filled with zeolite. The substrate, carbon, and zeolite form a composite material and enhance the flame retardant effect of the PVC / zeolite system.

[0004] Embedding zinc ions within the framework of 4A zeolite allows it to leverage its ability to absorb hydrogen chloride released by PVC degradation while also partially replacing zinc stearate. This simplifies the formulation of calcium and zinc heat stabilizers and provides functionalization, in line with product development. Since calcium and zinc are the only non-toxic and environmentally friendly stabilizers among many, and their usage is increasing year by year amidst the increasingly severe environmental protection situation, functionalizing 4A zeolite is crucial for adapting to the formulation needs of calcium and zinc stabilizers. Currently, calcium and zinc composite stabilizers refer to stabilizer products with zinc stearate, calcium stearate, and 4A zeolite as the main formula. Among them, zinc stearate is combined with the polymer carbon chain of PVC through the stearic acid group to prevent the further formation of conjugated double bonds, thereby improving the thermal stability of PVC resin. At the same time, the added zinc stearate plays an important role in improving the whiteness of the product. However, ZnCl2 will be generated in this process. ZnCl2 molecules also have a certain catalytic activity in accelerating the degradation of PVC. In severe cases, zinc burning will occur, affecting the processing and performance of the product. Therefore, the amount of zinc stearate added to the calcium and zinc stabilizer must be precise. Adding too much zinc stearate will cause the risk of zinc burning, while adding too little will affect the whiteness of the product.

[0005] Therefore, how to provide a new preparation method of zinc-added 4A zeolite molecular sieve to avoid using zinc stearate as a zinc adding agent to increase the risk of zinc burn or affect the whiteness of the product is a technical problem that urgently needs to be solved. Summary of the Invention

[0006] The present application provides a method for preparing zinc-added 4A zeolite molecular sieve to solve the technical problem in the prior art that adding too much zinc stearate will increase the risk of zinc burn, while adding too little will affect the whiteness of the product.

[0007] In a first aspect, the present application provides a method for preparing zinc-added 4A zeolite molecular sieve, the method comprising:

[0008] The sodium aluminate solution and the water glass solution are slurried and mixed, and then subjected to a first crystallization to obtain an initial crystallization slurry;

[0009] adding a sodium zincate solution to the initial crystallization slurry, and performing a second crystallization, followed by separation, washing, and drying to obtain a 4A zeolite molecular sieve product;

[0010] Wherein, the time of the first crystallization is 0.2h to 0.8h;

[0011] The content of zinc oxide in the sodium zincate solution is 60 g / L to 180 g / L.

[0012] Optionally, the sodium aluminate solution, the water glass solution and the sodium zincate solution meet the following requirements:

[0013] x:y:z=5~12:5~35:6~18;

[0014] Wherein, x is the content of aluminum oxide in the sodium aluminate solution, y is the content of silicon oxide in the water glass solution, and z is the content of zinc oxide in the sodium zincate solution.

[0015] Optionally, the content of aluminum oxide in the sodium aluminate solution is 50 g / L to 120 g / L, and the αk of the sodium aluminate solution is 1.4 to 3.5.

[0016] Optionally, the content of aluminum oxide in the sodium aluminate solution is 60 g / L to 80 g / L, and the αk of the sodium aluminate solution is 2.0 to 2.5.

[0017] Optionally, the content of silicon oxide in the water glass solution is 50 g / L to 350 g / L, and the water glass modulus M of the water glass solution is 1.0 to 3.5.

[0018] Optionally, the content of silicon oxide in the water glass solution is 200 g / L to 300 g / L, and the water glass modulus M of the water glass solution is 2.0 to 3.0.

[0019] Optionally, the temperature of the first crystallization is ≤ the temperature of the second crystallization, and the temperature of the first crystallization is 65°C to 75°C.

[0020] Optionally, the content of zinc oxide in the sodium zincate solution is 80 g / L to 120 g / L.

[0021] Optionally, the target crystallinity of the first crystallization is 10% to 30%.

[0022] Optionally, the second crystallization time is ≥3h.

[0023] The above technical solution provided by the embodiment of the present application has the following advantages compared with the prior art:

[0024] The present invention provides a method for preparing a zinc-added 4A zeolite molecular sieve. The method is based on a conventional 4A zeolite synthesis process and controls the specific time of the first crystallization so that the sodium zincate solution is added during the initial crystallization stage of the sodium aluminate solution and the water glass solution. During the initial crystallization stage, the aluminum oxide in the sodium aluminate solution and the silicon oxide in the water glass solution initially form a porous gel, but the gel structure is not yet fixed. Therefore, after the sodium zincate solution is added, the zinc ions formed by the hydrolysis of the sodium zincate solution can enter the porous gel. The specific content of zinc oxide in the sodium zincate solution is then controlled to form a zeolite molecular sieve gel precursor containing zinc ions. Subsequently, the zinc-added 4A zeolite molecular sieve product can be obtained through subsequent separation, washing, and drying. Since the zinc ions are added in the form of a sodium zincate solution, the addition of zinc stearate is avoided, and a newly functionalized zinc-added 4A zeolite molecular sieve is obtained. This can avoid excessive addition of zinc stearate, which causes zinc burn, or insufficient addition, which affects the whiteness of the product. 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 briefly introduces 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 any creative work.

[0027] Figure 1 A schematic flow chart of a method for preparing zinc-added 4A zeolite molecular sieve provided in an embodiment of the present application. DETAILED DESCRIPTION

[0028] To make the purpose, technical solutions, and advantages of the embodiments of this application more clear, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0029] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this application can be purchased from the market or prepared by existing methods.

[0030] like Figure 1 As shown, the present embodiment provides a method for preparing zinc-added 4A zeolite molecular sieve, the method comprising:

[0031] S1. The sodium aluminate solution and the water glass solution are slurried and mixed, and then subjected to a first crystallization to obtain an initial crystallization slurry;

[0032] S2. A sodium zincate solution was added to the initial crystallization slurry, and a second crystallization was performed, followed by separation, washing and drying to obtain a 4A zeolite molecular sieve product;

[0033] Wherein, the content of zinc oxide in the sodium zincate solution is 60g / L to 180g / L;

[0034] The first crystallization time is 0.2h to 0.8h.

[0035] In the embodiments of the present application, by controlling the specific content of zinc oxide in the sodium zincate solution, the content of zinc ions to be added can be refined, so that the zinc ions are sufficiently and fully dispersed into the crystal framework of the zeolite molecular sieve, thereby giving the 4A zeolite new functionalization.

[0036] The content of zinc oxide in the sodium zincate solution can be 60 g / L, 70 g / L, 80 g / L, 90 g / L, 100 g / L, 110 g / L, 120 g / L, 130 g / L, 140 g / L, 150 g / L, 160 g / L, 170 g / L, or 180 g / L.

[0037] By controlling the specific time of the first crystallization, the timing when the initial crystallization slurry begins to gradually transform into a molecular sieve product with a porous three-dimensional structure can be further determined in conjunction with the target crystallinity.

[0038] The first crystallization time can be 0.2 h, 0.3 h, 0.4 h, 0.5 h, 0.6 h, 0.7 h, or 0.8 h.

[0039] In some optional embodiments, the sodium aluminate solution, the water glass solution and the sodium zincate solution satisfy:

[0040] x:y:z=5~12:5~35:6~18;

[0041] Wherein, x is the content of aluminum oxide in the sodium aluminate solution, y is the content of silicon oxide in the water glass solution, and z is the content of zinc oxide in the sodium zincate solution.

[0042] In the embodiments of the present application, by controlling the specific mass ratios of the aluminum oxide content in the sodium aluminate solution, the silicon oxide content in the water glass solution, and the zinc oxide content in the sodium zincate solution, the zinc ions in the sodium zincate solution can be introduced into the initial crystallization slurry on the basis of sufficient reaction between the sodium aluminate solution and the water glass solution. The zinc ions can be introduced into the crystal framework of the zeolite molecular sieve by utilizing a hydrothermal conversion reaction, thereby imparting new functionalization to the zinc-added 4A zeolite.

[0043] The ratio can be 5:5:6, or 5:10:6, or 5:15:6, or 5:20:6, or 5:25:6, or 5:30:6, or 5:5:8, or 5:5:10, or 5:5:12, or 5:5:14, or 5:5:16, or 5:5:18, or 7:5:6, or 7:10:6, or 7:15:6, or 7:20:6, or 7:25:6, or 7:30:6, or 7:5:8, or 7:5:10, or 7:5:12, or 7:5:14, or 7:5:16, or 7:5:18, or It can be 9:5:6, 9:10:6, 9:15:6, 9:20:6, 9:25:6, 9:30:6, 9:5:8, 9:5:10, 9:5:12, 9:5:14, 9:5:16, 9:5:18, 12:5:6, 12:10:6, 12:15:6, 11:20:6, 12:25:6, 12:30:6, 12:5:8, 12:5:10, 12:5:12, 12:5:14, 12:5:16, and 12:5:18.

[0044] In some optional embodiments, the content of aluminum oxide in the sodium aluminate solution is 50 g / L to 120 g / L, and the αk of the sodium aluminate solution is 1.4 to 3.5.

[0045] In some optional embodiments, the content of aluminum oxide in the sodium aluminate solution is 60 g / L to 80 g / L, and the αk of the sodium aluminate solution is 2.0 to 2.5.

[0046] In the examples of the present application, controlling the specific content of aluminum oxide in the sodium aluminate solution and the specific value of αk can indicate the specific distribution and content of aluminum oxide in the sodium aluminate solution, thereby facilitating the subsequent acquisition of a 4A zeolite molecular sieve product with the expected three-dimensional structure.

[0047] The content of aluminum oxide in the sodium aluminate solution can be 50 g / L, 55 g / L, 60 g / L, 65 g / L, 70 g / L, 75 g / L, 80 g / L, 85 g / L, 90 g / L, 95 g / L, 100 g / L, 105 g / L, 110 g / L, 115 g / L, or 120 g / L.

[0048] The αk of the sodium aluminate solution may be 2.0, 2.1, 2.2, 2.3, 2.4, or 2.5.

[0049] In some optional embodiments, the content of silicon oxide in the water glass solution is 50 g / L to 350 g / L, and the water glass modulus M of the water glass solution is 1.0 to 3.5.

[0050] In some optional embodiments, the content of silicon oxide in the water glass solution is 200 g / L to 300 g / L, and the water glass modulus M of the water glass solution is 2.0 to 3.0.

[0051] In the embodiments of the present application, controlling the specific content of silicon oxide and the specific water glass modulus in the water glass solution can indicate the specific distribution and content of silicon oxide in the water glass solution, thereby facilitating the subsequent acquisition of a 4A zeolite molecular sieve product with an expected three-dimensional structure.

[0052] The content of silicon oxide in the water glass solution can be 50g / L, 60g / L, 70g / L, 80g / L, 90g / L, 100g / L, 110g / L, 120g / L, 130g / L, 140g / L, 150g / L, 160g / L, 170g / L, 180g / L, 190g / L, 200g / L, or 210g / L. So it can be 210g / L, or 200g / L, or 210g / L, or 220g / L, or 230g / L, or 240g / L, or 250g / L, or 260g / L, or 270g / L, or 280g / L, or 290g / L, or 300g / L, or 310g / L, or 320g / L, or 330g / L, or 340g / L, or 350g / L.

[0053] The water glass modulus M of the water glass solution can be 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9 or 3.0.

[0054] In some optional embodiments, the temperature of the first crystallization is ≤ the temperature of the second crystallization, and the temperature of the first crystallization is 65°C to 75°C.

[0055] In the embodiment of the present application, the specific temperature of the first crystallization is controlled, and a 4A zeolite molecular sieve product with the desired porous structure can be obtained through the reaction between the sodium aluminate solution and the water glass solution at this temperature.

[0056] The temperature of the first crystallization may be 65°C, 66°C, 67°C, 68°C, 69°C, 70°C, 71°C, 72°C, 73°C, 74°C, or 75°C.

[0057] In some optional embodiments, the content of zinc oxide in the sodium zincate solution is 80 g / L to 120 g / L.

[0058] In the embodiments of the present application, the specific content of zinc oxide in the sodium zincate solution is controlled. On the basis of clarifying the distribution and content of aluminum oxide in the sodium aluminate solution and silicon oxide in the water glass solution, the content of zinc ions to be added can be further refined, so that the zinc ions are sufficiently and fully dispersed into the crystal framework of the zeolite molecular sieve, thereby giving the 4A zeolite new functionalization.

[0059] In some optional embodiments, the target crystallinity of the first crystallization is 10% to 30%.

[0060] In some optional embodiments, the target crystallinity of the first crystallization is 15% to 28%.

[0061] In the examples of the present application, the specific target crystallinity of the first crystallization is controlled, indicating that the initial crystallization slurry begins to gradually transform into a molecular sieve product with a porous three-dimensional structure. At this time, the addition of sodium zincate solution can make the zinc ions evenly dispersed on the crystal skeleton as the crystallization proceeds, thereby giving the zinc-added 4A zeolite new functionalization.

[0062] The target crystallinity may be 10%, 15%, 18%, 21%, 24%, 27%, 28%, or 30%.

[0063] In some optional embodiments, the second crystallization time is ≥3 h.

[0064] In the embodiment of the present application, the specific time of the second crystallization is controlled so that the initial crystallization slurry can be completely converted into a 4A zeolite molecular sieve product with a porous three-dimensional structure after the addition of the sodium zincate solution, thereby obtaining a zinc-added 4A zeolite molecular sieve product.

[0065] The present application will be further described below in conjunction with specific examples. It should be understood that these examples are intended to illustrate the present application only and are not intended to limit the scope of the present application. The experimental methods in the following examples where specific conditions are not specified are usually measured in accordance with national standards. If there are no corresponding national standards, then the methods are carried out in accordance with general international standards, conventional conditions, or according to the conditions recommended by the manufacturer.

[0066] Example 1

[0067] The concentration of sodium aluminate solution is controlled to be Al2O3=75g / L and αk=2.0, the concentration of water glass is controlled to be SiO2=294g / L and M=2.98, the slurry ratio (concentration ratio) is Si:Al=1.95, and the two solutions are continuously injected into the slurry tank. The slurry volume entering the crystallization tank from the slurry tank is 40m 3 .

[0068] Crystallize at 75℃ for 0.5h, then add sodium zincate solution (ZnO = 98g / L, total 3m 3 ), and then continued to crystallize at 75 ° C for 3 hours, and then separated, washed and dried to obtain the product, which is numbered P-2.

[0069] Example 2

[0070] Comparing Example 2 with Example 1, the difference between Example 2 and Example 1 is:

[0071] The concentration of sodium aluminate solution is controlled to be Al2O3=75g / L and αk=2.0, the concentration of water glass is controlled to be SiO2=294g / L and M=2.98, the slurry ratio (concentration ratio) is Si:Al=1.95, and the two solutions are continuously injected into the slurry tank. The slurry volume entering the crystallization tank from the slurry tank is 40m 3 .

[0072] Crystallize at 75℃ for 0.5h, then add sodium zincate solution (ZnO=85g / L, total 6m 3 ), and then continued to crystallize at 75 ° C for 3 hours, and then separated, washed and dried to obtain the product, which is numbered P-3.

[0073] Example 3

[0074] Comparing Example 3 with Example 1, the difference between Example 3 and Example 1 is:

[0075] The concentration of sodium aluminate solution is controlled to be Al2O3=70g / L and αk=1.96, the concentration of water glass is SiO2=279g / L and M=3.0, the slurry ratio (concentration ratio) is Si:Al=2.0, and the two solutions are continuously injected into the slurry tank. The slurry volume entering the crystallization tank from the slurry tank is 40m 3 .

[0076] Crystallize at 68℃ for 1h, then add sodium zincate solution (ZnO = 105g / L, total 2.5m 3 ), the temperature was raised to 75°C and crystallized for 3 h, and then the product was obtained after separation, washing and drying. The product number is P-4.

[0077] Example 4

[0078] Comparing Example 4 with Example 1, the difference between Example 4 and Example 1 is:

[0079] The concentration of sodium aluminate solution is controlled to be Al2O3=64.5g / L and αk=2.23, the concentration of water glass is SiO2=238g / L and M=2.47, the slurry ratio (concentration ratio) is Si:Al=1.8, and the two solutions are continuously injected into the slurry tank. The slurry volume entering the crystallization tank from the slurry tank is 40m 3 .

[0080] Crystallize at 68℃ for 1h, then add sodium zincate solution (ZnO = 100g / L, total 4m 3 ), the temperature was raised to 95°C and crystallized for 3 h, and then the product was obtained after separation, washing and drying. The product number is P-5.

[0081] Comparative Example 1

[0082] Comparing Comparative Example 1 with Example 1, the difference between Comparative Example 1 and Example 1 is:

[0083] The concentration of sodium aluminate solution is controlled to be Al2O3=75g / L and αk=2.0, the concentration of water glass is controlled to be SiO2=294g / L and M=2.98, the slurry ratio (concentration ratio) is Si:Al=1.95, and the two solutions are continuously injected into the slurry tank. The slurry volume entering the crystallization tank from the slurry tank is 40m 3 .

[0084] After crystallization at 75°C for 3 hours, the product was obtained after separation, washing and drying, and the product number was P-1.

[0085] Related experiments and effect data:

[0086] The chemical compositions of products P-1, P-2, P-3, P-4 and P-5 were compared, and the results are shown in Table 1.

[0087] Table 1 Chemical composition results of the products of each embodiment and comparative example

[0088] serial number <![CDATA[SiO2(%)]]> <![CDATA[Al2O3(%)]]> <![CDATA[Na2O(%)]]> ZnO (%) P-1 32.19 27.68 16.67 0 P-2 32.11 26.64 15.86 5.7 P-3 32.39 27.53 15.67 6.7 P-4 31.28 26.89 16.11 6.0 P-5 30.25 26.27 14.98 10.1

[0089] As can be seen from Table 1, the present application can effectively introduce zinc oxide without affecting the silicon oxide, aluminum oxide and sodium oxide in the final 4A zeolite molecular sieve. The content of the introduced zinc oxide is above 5%, and there is no need to introduce a new preparation process. Only the timing of adding raw materials and the synthesis ratio in the synthesis stage need to be adjusted. The process is simple, easy to operate, and can save a lot of investment.

[0090] In summary, the embodiment of the present application provides a method for preparing a zinc-added 4A zeolite molecular sieve. In the existing process of synthesizing 4A zeolite from sodium aluminate solution and water glass solution, by adding sodium zincate solution at the initial stage of crystallization, a 4A zeolite product with new functionalization can be produced. Its functionalization is manifested in that it can not only exert its characteristic of absorbing hydrogen chloride released by PVC degradation in the stabilizer, but also partially or completely replace the role of zinc stearate, making the formulation design of calcium and zinc heat stabilizers simpler.

[0091] 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 hard 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 numbers within the range. For example, the description of a range 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 applies 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.

[0092] 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 present application specification, the terms "including", "comprising", etc. mean "including but not limited to". In this article, relational terms such as "first" and "second" are merely used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. In this article, "and / or" describes the association relationship of associated objects, indicating that three relationships can exist. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. Wherein A and B can be singular or plural. In this article, "at least one" refers to one or more, and "plurality" refers to two or more. "At least one", "at least one of the following" or similar expressions refer to any combination of these items, including any combination of single or plural items. 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, ab (i.e., a and b), ac, bc, or abc, where a, b, c can be single or multiple.

[0093] The foregoing is merely a list of specific embodiments of the present application, intended to enable those skilled in the art to understand or implement the present application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application is not limited to the embodiments shown herein, but is intended to conform to the broadest scope consistent with the principles and novel features of the present application.

Claims

1. A method for preparing zinc-added 4A zeolite molecular sieve, characterized in that: The method comprises: The sodium aluminate solution and the water glass solution are slurried and mixed, and then subjected to a first crystallization to obtain an initial crystallization slurry; adding a sodium zincate solution to the initial crystallization slurry, and performing a second crystallization, followed by separation, washing, and drying to obtain a 4A zeolite molecular sieve product; Wherein, the time of the first crystallization is 0.2h to 0.8h; The content of zinc oxide in the sodium zincate solution is 60g / L to 180g / L; The sodium aluminate solution, the water glass solution and the sodium zincate solution meet the following requirements: x:y:z=5~12:5~35:6~18; Wherein, x is the content of aluminum oxide in the sodium aluminate solution, y is the content of silicon oxide in the water glass solution, and z is the content of zinc oxide in the sodium zincate solution.

2. The preparation method according to claim 1, characterized in that The content of aluminum oxide in the sodium aluminate solution is 50 g / L to 120 g / L, and the αk of the sodium aluminate solution is 1.4 to 3.

5.

3. The preparation method according to claim 2, characterized in that The content of aluminum oxide in the sodium aluminate solution is 60 g / L to 80 g / L, and the αk of the sodium aluminate solution is 2.0 to 2.

5.

4. The preparation method according to claim 1, characterized in that The content of silicon oxide in the water glass solution is 50 g / L to 350 g / L, and the water glass modulus M of the water glass solution is 1.0 to 3.

5.

5. The preparation method according to claim 4, characterized in that The content of silicon oxide in the water glass solution is 200 g / L to 300 g / L, and the water glass modulus M of the water glass solution is 2.0 to 3.

0.

6. The preparation method according to claim 1, characterized in that The temperature of the first crystallization is less than or equal to the temperature of the second crystallization, and the temperature of the first crystallization is 65° C. to 75° C.

7. The preparation method according to claim 1, characterized in that The content of zinc oxide in the sodium zincate solution is 80 g / L to 120 g / L.

8. The preparation method according to claim 1, characterized in that The target crystallinity of the first crystallization is 10% to 30%.

9. The preparation method according to claim 1, characterized in that The second crystallization time is ≥3h.

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