A method for preparing a na-x, na-x / p molecular sieve

Abstract

The application discloses a preparation method of Na-X and Na-X / P molecular sieves, which comprises the following steps: step 1, dissolving an aluminum source in water to obtain an aluminum source solution; step 2, dissolving an alkali source in water to obtain an alkali source solution, and then adding the alkali source solution into the aluminum source solution to obtain a mixed solution; step 3, adding a silicon source into the mixed solution under stirring, and then adding water after the silicon source is added completely, and stirring to obtain a gel; step 4, adding Na-P crystal seeds into the gel, and then aging and dynamically crystallizing; the adding amount of the Na-P crystal seeds is 1%-3% of the mass of the gel; the dynamic crystallization conditions are as follows: the stirring speed is 100-220 r / min, the crystallization temperature is 90-100 DEG C, the heating rate is 0.5-30 DEG C / h, and the crystallization time is 0.5-6 h; and step 5, washing and drying the product after crystallization to obtain the Na-X and Na-X / P molecular sieves.

Description

Technical Field

[0001] This invention belongs to the field of molecular sieve catalytic material synthesis, specifically relating to a method for preparing Na-X and Na-X / P molecular sieves. Background Technology

[0002] X-type zeolite molecular sieves belong to the isometric crystal system and possess a cubic octahedral zeolite (FAU) structure. Their silicon-oxygen and aluminum-oxygen frameworks are identical to those of natural octahedral zeolite. The FAU framework contains two types of three-dimensional cavity structures: large cavities are supercages with a pore diameter of 12.7 Å; small cavities are p-cages with a pore diameter of 7.4 Å. Between 1949 and 1954, R.M. Milton and his colleague D.W. Breck successfully synthesized X-type zeolite, which shows promising applications in adsorption and separation. Na-P zeolite is an aluminosilicate zeolite composed of silicon-oxygen tetrahedra and aluminum-oxygen tetrahedra linked by oxygen atoms. Its structure is a two-dimensional staggered channel composed of two types of eight-membered oxygen ring channels with diameters of 3.1 Å x 4.4 Å and 2.6 Å x 4.9 Å, forming a GIS topology. Na-P zeolite has high cation exchange capacity and can be used for gas separation, removal of heavy metals from water, and as a detergent additive. Different adsorption scenarios require the application of zeolites with different adsorption capacities. Currently, most technical solutions use the gradation of Na-A / X and Na-Y / X molecular sieves to achieve changes in adsorption capacity. However, other impurities are prone to appear during the synthesis process, and the alkalinity of the solution is too high during the synthesis process, which causes corrosion to the reaction vessel.

[0003] Patent CN113548673A prepared NaX, NaA, NaP, NaX / NaA eutectic, NaX / NaP eutectic, NaA / NaP eutectic, or NaX / NaA / NaP eutectic molecular sieves. It uses lithium slag to prepare molecular sieves, which reduces the synthesis cost. However, this method requires the use of ultrasonic alkali dissolution, which makes it impossible to precisely control the adsorption capacity.

[0004] Patent CN110194467A uses NaY mother liquor to prepare 13X molecular sieves. NaY is used to provide silicon source and reduce wastewater discharge. However, the molecular sieves synthesized by this method have relatively limited adsorption capacity.

[0005] Patents CN101704533A, CN105600803A, and CN101289197A all incorporate seed X zeolite during the synthesis of X zeolite to shorten the synthesis time and increase the relative crystallinity of the synthesized product. However, the adsorption capacity of the synthesized molecular sieves is also relatively limited. Summary of the Invention

[0006] The purpose of this invention is to provide a method for preparing Na-X and Na-X / P molecular sieves, in order to solve the problems that the adsorption capacity of existing Na-X zeolites is basically fixed, and the high concentration of inorganic alkali solution used in the synthesis process is easy to cause corrosion to the synthesis reaction vessel.

[0007] To achieve the above objectives, the present invention provides a method for preparing Na-X and Na-X / P molecular sieves, comprising the following steps:

[0008] Step 1: Dissolve the aluminum source in water to obtain an aluminum source solution;

[0009] Step 2: Dissolve the alkali source in water to obtain an alkali source solution, and then add the alkali source solution to the aluminum source solution to obtain a mixed solution;

[0010] Step 3: Add the silicon source to the mixed solution under stirring. After the silicon source is added, add water and stir to obtain a gel.

[0011] Step 4: Add Na-P seed crystals to the gel, then age and dynamically crystallize; the amount of Na-P seed crystals added is 1%-3% of the gel mass; the dynamic crystallization conditions are: stirring speed 100-220 rpm, crystallization temperature 90-100℃, heating rate 0.5-30℃ / h, and crystallization time 0.5-6h.

[0012] Step 5: Wash and dry the crystallized product to obtain Na-X and Na-X / P molecular sieves.

[0013] In the preparation method of Na-X and Na-X / P molecular sieves of the present invention, the silicon source is measured by the content of silicon dioxide, and the molar ratio of H2O to silicon source in the gel is 52-75:1.

[0014] The preparation method of Na-X and Na-X / P molecular sieves of the present invention has a molar ratio of silicon source to aluminum source of 1.2-3.7:1, preferably 1.5-3.5:1, and a molar ratio of alkali source to silicon source of 1.4-4.1:1, preferably 1.6-4.0:1.

[0015] The method for preparing Na-X and Na-X / P molecular sieves according to the present invention includes an alkali source comprising alkali metal oxides and / or alkali metal hydroxides, and an alkali metal salt, wherein the molar ratio of the alkali metal salt to the alkali metal oxides and / or alkali metal hydroxides is 0.1-0.4:1; the alkali metal salt is a carbonate and / or a bicarbonate, preferably a carbonate.

[0016] The method for preparing Na-X and Na-X / P molecular sieves according to the present invention uses Na as the alkali metal, and preferably, the alkali source is sodium hydroxide and sodium carbonate.

[0017] The method for preparing Na-X and Na-X / P molecular sieves according to the present invention further includes an oxide and / or hydroxide of a metal selected from at least one of K, Li, Mg, and Ca, wherein the molar ratio of the oxide and / or hydroxide of the metal selected from at least one of K, Li, Mg, and Ca to the silicon source is 0.01-0.5:1.

[0018] The preparation method of Na-X and Na-X / P molecular sieves of the present invention includes aging at 40-80℃ for 1-8 hours and drying at 100-120℃ for 2-3 hours.

[0019] In the preparation method of Na-X and Na-X / P molecular sieves of the present invention, the impeller used for stirring during the crystallization process is one or more of the following: straight blade horizontal push impeller, straight blade downward pressure impeller, and anchor impeller.

[0020] The preparation method of Na-X and Na-X / P molecular sieves of the present invention has a blade diameter of D, the distance between the blade and the inner wall of the crystallization vessel is less than 0.5D, the distance between the lower edge of the blade and the bottom of the crystallization vessel is less than 0.2D, and the blade width of the straight blade horizontal pusher and the straight blade downward presser is not less than one-tenth of the height of the crystallization vessel.

[0021] The method for preparing Na-X and Na-X / P molecular sieves according to the present invention uses aluminum source which is one or more of water-soluble aluminum salts, alkali metal aluminates, aluminum alkoxides and metallic aluminum, preferably one or more of aluminum sulfate, sodium aluminate, aluminum nitrate, aluminum hydroxide, hydrated alumina and aluminum isopropoxide; and silicon source which is one or more of water glass, silica, sodium silicate, tetraethyl orthosilicate, silica gel and diatomaceous earth, preferably water glass.

[0022] Beneficial effects of this invention:

[0023] This invention uses Na-P zeolite as seed crystals, primarily acting as a guiding agent. Through the formulation of seed crystals and raw materials, heteronuclear transformation and competitive growth occur during crystallization, synthesizing Na-X zeolite and Na-X / P zeolite. By varying the amount of seed crystals added and controlling the heating rate and crystallization method—such as adjusting the agitator speed and type to alter the degree of material disturbance—the growth ratio of Na-X and Na-P can be controlled. This allows for precise adjustment of the adsorption capacity of the synthesized product, with the Na-P content ranging from 0% to 95% and the adsorption capacity flexibly adjustable from 10⁻³⁵. Furthermore, the addition of Na-P effectively reduces the amount of inorganic alkali required in the raw materials, lowering the alkalinity of the mixture and ensuring long-term use of the reactor. Attached Figure Description

[0024] Figure 1 These are XRD patterns of Embodiments 1 to 5 of the present invention. Detailed Implementation

[0025] The present invention will now be described in detail through embodiments. It should be noted that the following embodiments are only for further illustration of the present invention and should not be construed as limiting the scope of protection of the present invention. Those skilled in the art can make some non-essential improvements and adjustments to the present invention based on the above description.

[0026] Source of raw materials or equipment: including raw material name, specifications, manufacturer, etc.

[0027]

[0028] Evaluation and analysis methods:

[0029] XRD measurements were performed on a Bruker diffractometer. A Cu target K was used. α The light source was a graphite monochromator (λ = 0.15432 nm) with a tube voltage of 40 kV and a tube current of 40 mA. The scanning speed was 10° / min in the 5–55° range. Qualitative analysis was performed using JCPDS (Junior High-Performance Diagram Data Sheet).

[0030] The adsorption capacity was tested using dried molecular sieves. The test principle is to use a balance to weigh the sample and read the weight, and use a pressure sensor to read the pressure, thereby obtaining the weight value of the sample under a certain pressure. The adsorption capacity of the product for carbon dioxide at 25℃ can be obtained. Specific implementation examples:

[0032] Example 1

[0033] (1) First, dissolve 31.70g of sodium aluminate Y in 42.56g of water and stir until a clear solution is obtained;

[0034] (2) Dissolve 42.55g of sodium hydroxide (M1) and 12.40g of sodium carbonate (M2) in 183.64g of water, stir until a clear solution is obtained, and then add dropwise the clear solution from step (1) to obtain a mixed solution.

[0035] (3) After the aluminum source and the alkali source are completely mixed, 151.34g of water glass X is slowly added dropwise to the mixed solution in step (2) under vigorous stirring;

[0036] (4) After adding 361.69g of water and mixing evenly, a gel was obtained. The final molar ratio of H2O to water glass X (calculated as SiO2) in the gel was 53:1.

[0037] (5) Add 3% of the total weight of the mixture, 25.23g of Na-P seed crystals, to the mixture;

[0038] (6) The resulting mixture was aged at 80°C for 1 hour;

[0039] (7) The obtained gel was crystallized at 100℃ for 6 hours under closed conditions; the heating rate was 20℃ / h, the crystallization reaction was carried out under dynamic conditions, the stirring speed was 200 rpm, and the impeller shape was a straight blade downward pressure impeller.

[0040] (8) Wash the crystallized product with distilled water and dry it at 100°C for 2 hours.

[0041] The resulting gel had the following proportions: X:Y = 3.7:1, M:X = 1.4:1, M2:M1 = 0.1, and H2O:X = 53. Figure 1 As shown, the main characteristic peak positions of Na-X in this molecular sieve are 6.1°, 23.61°, and 32.01°, which are the same as the characteristic peak positions on the standard card PDF#38-0237. The main characteristic peak positions of Na-P in this molecular sieve are 12.46°, 17.73°, 21.65°, 28.18°, and 33.44°, which are the same as the characteristic peak positions on the standard card PDF#44-0052. The product is a Na-X / P eutectic molecular sieve, and the synthesized product has a Na-P zeolite content of 95% and a Na-X zeolite content of 5%.

[0042] Example 2

[0043] (1) First, dissolve 32.59g of sodium aluminate Y in 43.75g of water and stir until a clear solution is obtained;

[0044] (2) Dissolve 24.47g of sodium hydroxide (M1) and 28.53g of sodium carbonate (M2) in 253.35g of water, stir until a clear solution is obtained, and then add dropwise the clear solution from step (1) to obtain a mixed solution;

[0045] (3) After the aluminum source and the alkali source are completely mixed, 151.34g of water glass X is slowly added dropwise to the mixed solution in step (2) under vigorous stirring;

[0046] (4) After adding 252.12g of water and mixing evenly, a gel is obtained. The final molar ratio of H2O to water glass X (calculated as SiO2) in the gel is 50:1.

[0047] (5) Add 16.18g of Na-P seed crystals, which is 2% of the total weight of the mixture, to the mixture;

[0048] (6) The resulting mixture was aged at 40°C for 6 hours;

[0049] (7) The obtained gel was crystallized at 95℃ for 0.5h in a closed environment; the heating rate was 18℃ / h, and the crystallization reaction was carried out by selecting a downward pressure paddle with a rotation speed of 100 rpm. The paddle shape was a straight blade downward pressure paddle.

[0050] (8) The crystallized product was washed with distilled water and dried at 90°C for 3 hours. The ratio of the resulting gel was: X:Y = 3.6:1, M:X = 1.6:1, M2:M1 = 0.2, H2O:X = 50.

[0051] Depend on Figure 1 As shown, the main characteristic peak positions of Na-X in this molecular sieve are 6.1°, 9.86°, 11.73°, 15.45°, 18.43°, 20.07°, 23.61°, 27.39°, 30.33°, 32.01°, and 33.63°, which are the same as the characteristic peak positions on the standard card PDF#38-0237. The main characteristic peak positions of Na-P in this molecular sieve are 12.46°, 17.73°, 21.65°, 28.18°, and 33.44°, which are the same as the characteristic peak positions on the standard card PDF#44-0052. The product is a Na-X / P eutectic molecular sieve, and the synthesized product has a Na-P zeolite content of 36% and a Na-X zeolite content of 64%.

[0052] Example 3

[0053] (1) First, dissolve 39.10g of sodium aluminate Y in 52.48g of water and stir until a clear solution is obtained;

[0054] (2) Dissolve 79.37g of sodium hydroxide (M1) and 23.14g of sodium carbonate (M2) in 342.58g of water, stir until a clear solution is obtained, and then add the clear solution from step (1) dropwise to obtain a mixed solution;

[0055] (3) After the aluminum source and the alkali source are completely mixed, 151.34g of water glass X is slowly added dropwise to the mixed solution in step (2) under vigorous stirring;

[0056] (4) After adding 283.15g of water and mixing evenly, a gel is obtained. The final molar ratio of H2O to water glass X (calculated as SiO2) in the gel is 60:1.

[0057] (5) Add 9.7g of Na-P seed crystals, which is 1% of the total weight of the mixture, to the mixture;

[0058] (6) The resulting mixture was aged at 60°C for 3 hours;

[0059] (7) The obtained gel was crystallized at 80℃ for 4 hours in a closed environment; the heating rate was 30℃ / h, and the crystallization reaction was carried out by selecting an anchor paddle with a rotation speed of 220 rpm. The paddle shape was an anchor paddle.

[0060] (8) The crystallized product was washed with distilled water and dried at 100°C for 2 hours. The ratio of the resulting gel was: X:Y = 3.0:1, M:X = 2.1:1, M2:M1 = 0.1, H2O:X = 60.

[0061] Depend on Figure 1 As shown, the main characteristic peak positions of Na-X in this molecular sieve are 6.1°, 9.86°, 11.73°, 15.45°, 18.43°, 20.07°, 23.61°, 27.39°, 30.33°, 32.01°, and 33.63°, which are the same as the characteristic peak positions on the standard card PDF#38-0237. The main characteristic peak positions of Na-P in this molecular sieve are 12.46°, 17.73°, 21.65°, 28.18°, and 33.44°, which are the same as the characteristic peak positions on the standard card PDF#44-0052. The product is a Na-X / P eutectic molecular sieve, and the synthesized product has a Na-P zeolite content of 10% and a Na-X zeolite content of 90%.

[0062] Example 4

[0063] (1) First, dissolve 19.55g of sodium aluminate Y in 26.24g of water and stir until a clear solution is obtained;

[0064] (2) Dissolve 105.75g of sodium hydroxide (M1) and 117.14g of sodium carbonate (M2) in 444.88g of water, stir until a clear solution is obtained, and then add dropwise the clear solution from step (1) to obtain a mixed solution.

[0065] (3) After the aluminum source and the alkali source are completely mixed, 90.80g of water glass X is slowly added dropwise to the mixed solution in step (2) under vigorous stirring;

[0066] (4) After adding 36.31g of water and mixing evenly, a gel was obtained. The final molar ratio of H2O to water glass X (calculated as SiO2) in the gel was 73:1.

[0067] (5) Add 8.4g of Na-P seed crystals, which is 1% of the total weight of the mixture, to the mixture;

[0068] (6) The resulting mixture was aged at 40°C for 8 hours;

[0069] (7) The obtained gel was crystallized at 80℃ for 1h in a closed environment; the heating rate was 13℃ / h, and the crystallization reaction was carried out under the condition of 220 rpm of anchor paddle. The paddle shape was anchor paddle.

[0070] (8) Wash the crystallized product with distilled water and dry it at 100°C for 2 hours.

[0071] The resulting gel has the following ratios: X:Y = 3.6:1, M:X = 4:1, M2:M1 = 0.38, and H2O:X = 73.

[0072] Depend on Figure 1 As shown, the main characteristic peak positions of this molecular sieve are 6.1°, 9.86°, 11.73°, 15.45°, 18.43°, 20.07°, 23.61°, 27.39°, 30.33°, 32.01°, and 33.63°. These positions are the same as those on the standard card in PDF#38-0237, indicating that a Na-X molecular sieve was successfully prepared without any other impurities.

[0073] Example 5

[0074] (1) First, dissolve 28.53g of sodium aluminate Y in 38.29g of water and stir until a clear solution is obtained;

[0075] (2) Dissolve 43.49g of sodium hydroxide (M1) and 38.04g of sodium carbonate (M2) in 119.57g of water, stir until a clear solution is obtained, and then add the clear solution from step (1) dropwise to obtain a mixed solution.

[0076] (3) After the aluminum source and the alkali source are completely mixed, 139.21g of water glass X is slowly added dropwise to the mixed solution in step (2) under vigorous stirring;

[0077] (4) After adding 475.66g of water and mixing evenly, a gel was obtained. The final molar ratio of H2O to water glass X (calculated as SiO2) in the gel was 62:1.

[0078] (5) Add 17.6g of Na-P seed crystals, which is 2% of the total weight of the mixture, to the mixture;

[0079] (6) The resulting mixture was aged at 80°C for 2 hours;

[0080] (7) The obtained gel was crystallized at 100℃ for 2 hours under closed conditions; the heating rate was 0.5℃ / h, and the crystallization reaction was carried out at a speed of 100 rpm for a straight blade impeller. The impeller shape was a straight blade downward pressure impeller.

[0081] (8) Wash the crystallized product with distilled water and dry it at 100°C for 2 hours.

[0082] The resulting gel has the following ratios: X:Y = 3.7:1, M:X = 1.7:1, M2:M1 = 0.3, and H2O:X = 62.

[0083] Depend on Figure 1As shown, the main characteristic peak positions of Na-X in this molecular sieve are 6.1°, 9.86°, 11.73°, 15.45°, 23.61°, 27.39°, and 32.01°, which are the same as the characteristic peak positions on the standard card PDF#38-0237. The main characteristic peak positions of Na-P in this molecular sieve are 12.46°, 17.73°, 21.65°, 28.18°, and 33.44°, which are the same as the characteristic peak positions on the standard card PDF#44-0052. The product is a Na-X / P eutectic molecular sieve, and the synthesized product has a Na-P zeolite content of 82% and a Na-X zeolite content of 18%.

[0084] Example 6

[0085] (1) First, dissolve 51.26g of aluminum sulfate Y in 68.79g of water and stir until a clear solution is obtained;

[0086] (2) Dissolve 24.47g of sodium hydroxide (M1), 28.53g of sodium carbonate (M2), and 27.29g of potassium hydroxide (M3) in 117.75g of water, stir until a clear solution is obtained, and then add the clear solution from step (1) dropwise to obtain a mixed solution.

[0087] (3) After the aluminum source and the alkali source are completely mixed, 95.58g of water glass X is slowly added dropwise to the mixed solution in step (2) under vigorous stirring;

[0088] (4) After adding 569.53g of water and mixing evenly, a gel is obtained. The final molar ratio of H2O to water glass X (calculated as SiO2) in the gel is 60:1.

[0089] (5) Add 9.4g of Na-P seed crystals, which is 1% of the total weight of the mixture, to the mixture;

[0090] (6) The resulting mixture was aged at 40°C for 6 hours;

[0091] (7) The obtained gel was crystallized at 90℃ for 4 hours in a closed environment; the heating rate was 16℃ / h, and the crystallization reaction was carried out at an anchor paddle speed of 220 rpm. The paddle shape was an anchor paddle.

[0092] (8) Wash the crystallized product with distilled water and dry it at 100°C for 2 hours.

[0093] The resulting gel has the following ratios: X:Y = 1.4:1, M:X = 2.1:1, M2:M1 = 0.4, M3:M1 = 0.3, H2O:X = 60.

[0094] The synthesized Na-P zeolite has a content of 5%, and the Na-X zeolite has a content of 95%.

[0095] The main characteristic peak positions of Na-X in this molecular sieve are 6.1°, 9.86°, 11.73°, 15.45°, 18.43°, 20.07°, 23.61°, 27.39°, 30.33°, 32.01°, and 33.63°, which are the same as the characteristic peak positions on the standard card PDF#38-0237. The main characteristic peak positions of Na-P in this molecular sieve are 12.46°, 21.65°, 28.18°, and 33.44°, which are the same as the characteristic peak positions on the standard card PDF#44-0052. The product is a Na-X / P eutectic molecular sieve, and the synthesized product has a Na-P zeolite content of 82% and a Na-X zeolite content of 18%.

[0096] Comparative Example 1

[0097] (1) First, dissolve 31.70g of sodium aluminate Y in 42.56g of water and stir until a clear solution is obtained;

[0098] (2) Dissolve 42.55g of sodium hydroxide (M1) and 12.40g of sodium carbonate (M2) in 183.64g of water, stir until a clear solution is obtained, and then add dropwise the clear solution from step (1) to obtain a mixed solution.

[0099] (3) After the aluminum source and the alkali source are completely mixed, 151.34g of water glass X is slowly added dropwise to the mixed solution in step (2) under vigorous stirring;

[0100] (4) After adding 361.69g of water and mixing evenly, a gel was obtained. The final molar ratio of H2O to water glass X (calculated as SiO2) in the gel was 53:1.

[0101] (5) Add 3% of the total weight of the mixture, 25.23g of Na-P seed crystals, to the mixture;

[0102] (6) The resulting mixture was aged at 80°C for 1 hour;

[0103] (7) The resulting gel was crystallized at 100℃ under sealed conditions for 6 hours;

[0104] (8) Wash the crystallized product with distilled water and dry it at 100°C for 2 hours.

[0105] The resulting gel had the following proportions: X:Y = 3.7:1, M:X = 1.4:1, M2:M1 = 0.1, and H2O:X = 53. The resulting product was a mixture of chabazite and Na-X.

[0106] Comparative Example 2

[0107] (1) First, dissolve 51.26g of sodium aluminate Y in 68.79g of water and stir until a clear solution is obtained;

[0108] (2) Dissolve 24.47g of sodium hydroxide (M1), 28.53g of sodium carbonate (M2), and 27.29g of potassium hydroxide (M3) in 117.75g of water, stir until a clear solution is obtained, and then add the clear solution from step (1) dropwise to obtain a mixed solution.

[0109] (3) After the aluminum source and the alkali source are completely mixed, 95.58g of water glass X is slowly added dropwise to the mixed solution in step (2) under vigorous stirring;

[0110] (4) After adding 569.53g of water and mixing evenly, a gel is obtained. The final molar ratio of H2O to water glass X (calculated as SiO2) in the gel is 60:1.

[0111] (5) Add 9.4g of Na-P seed crystals, which is 1% of the total weight of the mixture, to the mixture;

[0112] (6) The resulting mixture was aged at 40°C for 6 hours;

[0113] (7) The resulting gel was crystallized at 90°C for 4 hours in a closed environment.

[0114] (8) Wash the crystallized product with distilled water and dry it at 100°C for 2 hours.

[0115] The resulting gel had the following proportions: X:Y = 1.4:1, M:X = 2.1:1, M2:M1 = 0.4, M3:M1 = 0.3, H2O:X = 60.

[0116] The synthesized mixture of Na-X and chalcogenide.

[0117] Example 7:

[0118] The adsorption capacity of the zeolites synthesized in Examples 1, 2, 3, and 4 were tested respectively. The specific results and data are shown in Table 1. As can be seen from Table 1, the adsorption capacity for carbon dioxide is different for different contents of Na-P and Na-X.

[0119] Table 1 shows the adsorption capacity of carbon dioxide for products with Na-P and Na-X contents.

[0120]

[0121] Table 2. Proportions of each component in the examples and comparative examples.

[0122]

[0123]

[0124] Of course, the present invention may have other various embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and modifications according to the present invention, but these corresponding changes and modifications should all fall within the protection scope of the claims of the present invention.

Claims

1. A method for preparing Na-X and Na-X / P molecular sieves, characterized in that, Includes the following steps: Step 1: Dissolve the aluminum source in water to obtain an aluminum source solution; Step 2: Dissolve the alkali source in water to obtain an alkali source solution, and then add the alkali source solution to the aluminum source solution to obtain a mixed solution; Step 3: Add the silicon source to the mixed solution under stirring. After the silicon source is added, add water and stir to obtain a gel. Step 4: Add Na-P seed crystals to the gel, then age and dynamically crystallize; the amount of Na-P seed crystals added is 1%-3% of the gel mass; the dynamic crystallization conditions are: stirring speed 100-220 rpm, crystallization temperature 90-100℃, heating rate 0.5-30℃ / h, and crystallization time 0.5-6h. Step 5: Wash and dry the crystallized product to obtain Na-X and Na-X / P molecular sieves.

2. The method for preparing Na-X and Na-X / P molecular sieves according to claim 1, characterized in that, The molar ratio of H2O to silicon source in the gel is 52-75:1, based on the silica content.

3. The method for preparing Na-X and Na-X / P molecular sieves according to claim 1, characterized in that, The molar ratio of silicon source to aluminum source is 1.2-3.7:1, and the molar ratio of alkali source to silicon source is 1.4-4.1:

1.

4. The method for preparing Na-X and Na-X / P molecular sieves according to claim 1, characterized in that, The molar ratio of silicon source to aluminum source is 1.5-3.5:1, and the molar ratio of alkali source to silicon source is 1.6-4.0:

1.

5. The method for preparing Na-X and Na-X / P molecular sieves according to claim 1, characterized in that, The alkali source includes alkali metal oxides and / or alkali metal hydroxides, as well as alkali metal salts, wherein the molar ratio of the alkali metal salt to the alkali metal oxides and / or alkali metal hydroxides is 0.1-0.4:1; and the alkali metal salt is a carbonate and / or a bicarbonate.

6. The method for preparing Na-X and Na-X / P molecular sieves according to claim 5, characterized in that, The alkali metal salt is a carbonate.

7. The method for preparing Na-X and Na-X / P molecular sieves according to claim 5, characterized in that, The alkali metal is Na, and the alkali source is sodium hydroxide and sodium carbonate.

8. The method for preparing Na-X and Na-X / P molecular sieves according to claim 7, characterized in that, The alkali source also includes oxides and / or hydroxides of at least one metal selected from K, Li, Mg, and Ca, and the molar ratio of the oxides and / or hydroxides of at least one metal selected from K, Li, Mg, and Ca to the silicon source is 0.01-0.5:

1.

9. The method for preparing Na-X and Na-X / P molecular sieves according to claim 1, characterized in that, The aging conditions are aging at 40-80℃ for 1-8 hours; the drying conditions are drying at 100-120℃ for 2-3 hours.

10. The method for preparing Na-X and Na-X / P molecular sieves according to claim 1, characterized in that, The impeller used for stirring during crystallization is one or more of the following: straight-blade horizontal thrust impeller, straight-blade downward thrust impeller, and anchor impeller.

11. The method for preparing Na-X and Na-X / P molecular sieves according to claim 10, characterized in that, The blade diameter is D, the distance between the blade and the inner wall of the crystallization vessel is less than 0.5D, the distance between the lower edge of the blade and the bottom of the crystallization vessel is less than 0.2D, and the blade width of the straight blade horizontal pusher and the straight blade downward pusher is not less than one-tenth of the height of the crystallization vessel.

12. The method for preparing Na-X and Na-X / P molecular sieves according to claim 1, characterized in that, The aluminum source is one or more of water-soluble aluminum salts, alkali metal aluminates, aluminum alkoxides, and metallic aluminum; the silicon source is one or more of water glass, silica, sodium silicate, tetraethyl orthosilicate, silica gel, and diatomaceous earth.

13. The method for preparing Na-X and Na-X / P molecular sieves according to claim 12, characterized in that, The silicon source is water glass.

14. The method for preparing Na-X and Na-X / P molecular sieves according to claim 12, characterized in that, The aluminum source is one or more of aluminum sulfate, sodium aluminate, aluminum nitrate, aluminum hydroxide, hydrated aluminum oxide, and aluminum isopropoxide.

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