A 3A molecular sieve with high adsorption capacity and its preparation method

Abstract

This invention provides a 3A molecular sieve with high adsorption capacity and its preparation method, belonging to the field of molecular sieve technology. First, this invention prepares core spheres using 3A molecular sieve powder, 4A molecular sieve powder, and / or 5A molecular sieve powder, along with a binder. The mixed powder prepared by mixing the 3A molecular sieve powder and the binder is then coated onto the surface of the core spheres. A second molding process is performed to obtain core spheres with an outer shell. These are then preheated, calcined, and cooled sequentially to obtain a 3A molecular sieve with high adsorption capacity. The pore size of the outer shell of the 3A molecular sieve prepared in this invention remains at 3A, enabling it to adsorb any molecules with a diameter smaller than 3A while preventing molecules with a diameter larger than 3A from passing through. However, the average pore size of the core of the 3A molecular sieve prepared in this invention is larger than 3A, and the pore volume is also larger than that of the outer shell, thus increasing the overall pore volume. Due to the diffusion effect, the adsorption capacity is increased, achieving improved adsorption capacity while maintaining the original advantages of 3A molecular sieves and reducing their usage.

Description

Technical Field

[0001] This invention relates to the field of molecular sieve technology, and in particular to a 3A molecular sieve with high adsorption capacity and its preparation method. Background Technology

[0002] Molecular sieves are crystalline silicates or aluminosilicates. They possess a uniform microporous structure with consistent pore diameter. These pores adsorb molecules smaller than their diameter and preferentially adsorb polar and unsaturated molecules, thus separating molecules with different polarities, saturation levels, sizes, and boiling points—hence the name "molecular sieve." Due to their high adsorption capacity and strong thermal stability, which are unmatched by other adsorbents, molecular sieves have found wide applications. It is important to note that the adsorption capacity of molecular sieves is limited. When adsorption reaches saturation, regeneration is necessary to restore their adsorption capacity. Regeneration is typically achieved through heating or depressurization, causing the adsorbed molecules to desorb from the molecular sieve.

[0003] Based on their applications, molecular sieves are mainly classified into 3A, 4A, 5A, and 13X molecular sieves. 3A molecular sieves have a pore size of 0.3 nanometers (3A) and are potassium-type A-crystal structures with a very large specific surface area. They are primarily used for adsorbing water and do not adsorb any molecules with a diameter greater than 3A. 4A molecular sieves have a pore size of 0.4 nanometers (4A) and are sodium-type A-crystal structures. They can adsorb any molecules with a critical diameter not greater than 4A, such as water, methanol, ethanol, ethylene, propylene, hydrogen sulfide, sulfur dioxide, carbon dioxide, and ammonia. 5A molecular sieves have a pore size of 0.5 nanometers (5A) and are calcium-type A-crystal structures. They can adsorb any molecules with a diameter less than 5A. In addition to the functions of 3A and 4A molecular sieves, they can also adsorb C3-C4 n-alkanes, chloroethane, bromoethane, and butanol. 13X molecular sieves have a pore size of 1 nanometer (10 Å) and are sodium-type X-shaped crystals. They can adsorb any molecule with a diameter smaller than 10 Å and can be used as catalyst supports, for co-adsorption of water and carbon dioxide, and for co-adsorption of water and hydrogen sulfide gas. They are primarily used in pharmaceuticals and air compression systems for drying. 3A molecular sieves are mainly used for water adsorption and are suitable for drying gases and liquids, as well as dehydrating hydrocarbons. 3A molecular sieves are widely used for the deep drying of petroleum cracking gas, ethylene, propylene, and natural gas, and are the preferred desiccant for deep gas and liquid phase drying, refining, and polymerization in the petroleum and chemical industries.

[0004] Existing technologies have yielded numerous studies on the adsorption rate, regeneration cycles, crush resistance, and anti-fouling ability of 3A molecular sieves, but there are no reports on how to further improve the adsorption capacity of 3A molecular sieves. Summary of the Invention

[0005] The purpose of this invention is to provide a 3A molecular sieve with high adsorption capacity and its preparation method. The method provided by this invention significantly improves the adsorption capacity and adsorption ability of the 3A molecular sieve while maintaining its original advantages and reducing its usage.

[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0007] This invention provides a method for preparing 3A molecular sieves with high adsorption capacity, comprising the following steps:

[0008] (1) Mix 3A molecular sieve powder with 4A molecular sieve powder and / or 5A molecular sieve powder, then add binder, and stir and first form in sequence to obtain core spheres;

[0009] (2) Mix the 3A molecular sieve raw powder and the binder to obtain a mixed raw powder;

[0010] The mixed raw powder is wrapped around the surface of the core sphere obtained in step (1), and a second molding process is performed to obtain a core sphere with a shell, also known as a wet sphere;

[0011] (3) The wet bulbs obtained in step (2) are preheated, calcined and cooled in sequence to obtain 3A molecular sieve with high adsorption capacity.

[0012] Preferably, in step (1), the mass ratio of 3A molecular sieve powder to 4A molecular sieve powder and / or 5A molecular sieve powder is 1:(1-6).

[0013] Preferably, the binder in step (1) is clay, and the clay is at least one of kaolin, sepiolite, palygorskite and bentonite.

[0014] Preferably, in step (2), the mass ratio of 3A molecular sieve raw powder to binder is (3-5):1.

[0015] Preferably, in step (2), the ratio of the average diameter of the core sphere to the average thickness of the outer shell is (0.3-3):1.

[0016] Preferably, step (2) after the second forming process further includes sieving, polishing and rounding in sequence.

[0017] Preferably, the preheating temperature in step (3) is 400-600°C and the preheating time is 10-40 min.

[0018] Preferably, the water content of the preheated product obtained in step (3) is 5-15 wt%.

[0019] Preferably, the heating rate of calcination in step (3) is 6-14℃ / min, the calcination temperature is 600-780℃, and the calcination time is 1-3h.

[0020] The present invention also provides a 3A molecular sieve with high adsorption capacity prepared by the preparation method described in the above technical solution.

[0021] This invention provides a method for preparing a 3A molecular sieve with high adsorption capacity. First, 3A molecular sieve powder is mixed with 4A and / or 5A molecular sieve powder, and a binder is added. The mixture is then stirred and first-shaped to obtain core spheres. Next, the 3A molecular sieve powder and the binder are mixed to obtain a mixed powder. This mixed powder is then coated onto the surface of the core spheres, and a second-shaped process is performed to obtain core spheres with an outer shell, also known as wet spheres. These are then preheated, calcined, and cooled to obtain a 3A molecular sieve with high adsorption capacity. The 3A molecular sieve prepared by this invention maintains a pore size of 3A in the outer shell, enabling it to adsorb any molecules with a diameter smaller than 3A while preventing molecules larger than 3A from passing through. However, the inner core, prepared by mixing 3A, 4A, and / or 5A molecular sieve powders, has an average pore size greater than 3A and a larger pore volume than the outer shell, increasing the overall pore volume. Due to the diffusion effect, the adsorption capacity of the 3A molecular sieve is increased. This method significantly improves the adsorption capacity while maintaining the original advantages of 3A molecular sieves and reducing the amount used. Attached Figure Description

[0022] Figure 1 The static water adsorption rate bar charts are for the 3A molecular sieves with high adsorption capacity prepared in Examples 1-6 and Comparative Examples 1-4 of this invention. Detailed Implementation

[0023] This invention provides a method for preparing 3A molecular sieves with high adsorption capacity, comprising the following steps:

[0024] (1) Mix 3A molecular sieve powder with 4A molecular sieve powder and / or 5A molecular sieve powder, then add binder, and stir and first form in sequence to obtain core spheres;

[0025] (2) Mix the 3A molecular sieve raw powder and the binder to obtain a mixed raw powder;

[0026] The mixed raw powder is wrapped around the surface of the core sphere obtained in step (1), and a second molding process is performed to obtain a core sphere with a shell, also known as a wet sphere;

[0027] (3) The wet bulbs obtained in step (2) are preheated, calcined and cooled in sequence to obtain 3A molecular sieve with high adsorption capacity.

[0028] Unless otherwise specified, all raw materials used in this invention are commercially available products in the art.

[0029] This invention involves mixing 3A molecular sieve powder with 4A molecular sieve powder and / or 5A molecular sieve powder, then adding a binder, and sequentially stirring and first molding to obtain core spheres.

[0030] In this invention, the preferred mass ratio of the 3A molecular sieve powder to the 4A and / or 5A molecular sieve powder is 1:(1-6), more preferably 1:(1.5-4). This invention controls the mass ratio of the 3A molecular sieve powder to the 4A and / or 5A molecular sieve powder within the above range to improve the bonding between the core and shell of the prepared 3A molecular sieve, thereby enhancing its stability, extending its service life, and simultaneously improving the adsorption capacity of the prepared 3A molecular sieve.

[0031] In this invention, the binder is preferably clay; the clay is preferably at least one selected from kaolin, sepiolite, palygorskite, and bentonite. In this invention, the mass ratio of the total mass of molecular sieve powder to the binder in the core sphere is preferably (2-6):1, more preferably (3-5):1. This invention controls the mass ratio of the total mass of molecular sieve powder to the binder in the core sphere within the above range to ensure the shape of the core sphere and facilitate subsequent operations.

[0032] This invention does not impose any special limitations on the stirring method; any well-known technical solution in the art can be used to achieve uniform mixing of the components. This invention also does not impose any special limitations on the first molding method; any well-known method in the art can be used to obtain core spheres of the target particle size.

[0033] This invention mixes 3A molecular sieve raw powder and a binder to obtain a mixed raw powder;

[0034] In this invention, the preferred mass ratio of the 3A molecular sieve powder to the binder is (3-5):1. Controlling the mass ratio of the 3A molecular sieve powder to the binder within this range facilitates the stable and uniform coating of the mixed powder onto the surface of the core spheres, thereby improving the preparation of a 3A molecular sieve with stable performance.

[0035] After obtaining the mixed raw powder and the core sphere, the present invention coats the mixed raw powder on the surface of the core sphere, and obtains the core sphere with the outer shell after a second molding process, also known as a wet sphere;

[0036] In this invention, the ratio of the average diameter of the core spheres to the average thickness of the outer shell is preferably (0.3-3):1. This invention controls the ratio of the average particle size of the core spheres to the average thickness of the outer shell within the above range to ensure the preparation of a 3A molecular sieve with an outer shell adsorption pore size of 3 Å, thus maintaining the original advantages and performance of the 3A molecular sieve.

[0037] The present invention does not impose any special restrictions on the coating method; it is sufficient to coat the surface of the core sphere with a uniformly thick layer of mixed raw powder.

[0038] The present invention does not impose any special limitations on the second molding method; any wet ball with good sphericity can be obtained by using methods well known in the art.

[0039] After the second molding process, the present invention preferably involves sequentially sieving, polishing, and rounding the product formed in the second molding process.

[0040] This invention does not impose any special limitations on the sieving, polishing, and spheroidizing methods; the goal is to obtain 3A molecular sieves with high adsorption capacity and target particle size.

[0041] After obtaining the wet bulbs, the present invention preheats, calcines, and cools the wet bulbs sequentially to obtain 3A molecular sieves with high adsorption capacity.

[0042] In this invention, the preheating temperature is preferably 400–600°C, more preferably 450–580°C; the preheating time is preferably 10–40 min, more preferably 20–30 min. In this invention, the water content of the preheated spheres is preferably 5–15 wt%. This invention, by preheating and controlling the water content of the preheated spheres within the above range, removes most of the moisture from the wet spheres, improves the bonding between the outer shell and the core, enhances the strength of the subsequently prepared 3A molecular sieve, avoids powder shedding, and extends the service life.

[0043] In this invention, the heating rate of the calcination is preferably 6–14 °C / min, more preferably 7–12 °C; the calcination temperature is preferably 600–780 °C, more preferably 650–750 °C; and the calcination time is preferably 1–3 h. This invention controls the heating rate, temperature, and time of the calcination within the above ranges to improve the strength and stability of the prepared 3A molecular sieve and extend its service life.

[0044] The present invention also provides a 3A molecular sieve with high adsorption capacity prepared by the preparation method described in the above technical solution.

[0045] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0046] Example 1

[0047] A method for preparing 3A molecular sieves with high adsorption capacity, comprising the following steps:

[0048] (1) In the powder mixer, 3A molecular sieve raw powder and 4A molecular sieve raw powder are mixed, and then kaolin binder is added. After stirring, the powder is added while spraying water using the pelletizing machine and its own powder adding and water spraying device. The powder is rolled and gathered from small balls into large balls, completing the first molding and obtaining the core ball.

[0049] In step (1), the mass ratio of 3A molecular sieve powder to 4A molecular sieve powder is 1:2.

[0050] In step (1), the mass ratio of the total mass of molecular sieve powder in the core sphere to the mass of the binder is 3:1;

[0051] (2) Mix the 3A molecular sieve raw powder and the binder kaolin to obtain the mixed raw powder;

[0052] In step (2), the mass ratio of 3A molecular sieve raw powder to binder is 4:1;

[0053] The mixed raw powder is wrapped around the surface of the core ball obtained in step (1). A layer of mixed raw powder of uniform thickness is wrapped around the surface of the core ball. Using a ball forming machine and its own powder adding and water spraying device, water is sprayed and material is added at the same time to complete the second forming. Then, the core ball with the outer shell is obtained by sieving, polishing and rolling in sequence, also known as wet ball.

[0054] In step (2), the ratio of the average diameter of the core sphere to the average thickness of the outer shell is 0.5:1;

[0055] (3) The wet bulbs obtained in step (2) are preheated at 450°C for 20 min, and then calcined at 660°C for 2 h at a heating rate of 12°C / min. After cooling, 3A molecular sieve with high adsorption capacity and an average particle size of 2 mm is obtained.

[0056] Example 2

[0057] The 3A molecular sieve with high adsorption capacity was prepared according to the method of Example 1. The difference from Example 1 is that the ratio of the average diameter of the core sphere to the average thickness of the shell in step (2) is 1:1.

[0058] Example 3

[0059] The 3A molecular sieve with high adsorption capacity was prepared according to the method of Example 1. The difference from Example 1 is that the ratio of the average diameter of the core sphere to the average thickness of the shell in step (2) is 2:1.

[0060] Example 4

[0061] The 3A molecular sieve with high adsorption capacity was prepared according to the method of Example 1. The difference from Example 1 is that the ratio of the average diameter of the core sphere to the average thickness of the shell in step (2) is 3:1.

[0062] Example 5

[0063] The 3A molecular sieve with high adsorption capacity was prepared according to the method of Example 2. The difference from Example 2 is that the 4A molecular sieve raw powder in step (1) was replaced with an equal amount of 5A molecular sieve raw powder.

[0064] Example 6

[0065] The 3A molecular sieve with high adsorption capacity was prepared according to the method of Example 3. The difference from Example 3 is that the 4A molecular sieve raw powder in step (1) was replaced with an equal amount of 5A molecular sieve raw powder.

[0066] Comparative Example 1

[0067] The preparation steps of 3A molecular sieve are as follows:

[0068] In a powder mixer, 3A molecular sieve raw powder and binder kaolin are mixed at a mass ratio of 4:1 to obtain mixed raw powder. Using a pelletizing machine and its built-in powder adding and water spraying device, the powder is added while spraying water to complete the forming. Then, the pellets are sieved, polished and rolled to obtain wet pellets. They are then preheated at 450℃ for 20 minutes, and then calcined at 660℃ for 2 hours at a heating rate of 12℃ / min. After cooling, 3A molecular sieve with an average particle size of 2mm is obtained.

[0069] Comparative Example 2

[0070] The preparation steps of 3A molecular sieve are as follows:

[0071] In a powder mixer, 3A molecular sieve raw powder and binder kaolin are mixed at a mass ratio of 4:1 to obtain mixed raw powder. Using a pelletizing machine and its built-in powder adding and water spraying device, the powder is added while spraying water to complete the forming. Then, the pellets are sieved, polished and rolled to obtain wet pellets. They are then preheated at 450℃ for 20 minutes, and then calcined at 700℃ for 2 hours at a heating rate of 12℃ / min. After cooling, 3A molecular sieve with an average particle size of 2mm is obtained.

[0072] Comparative Example 3

[0073] The preparation steps of 3A molecular sieve are as follows:

[0074] In a powder mixer, 3A molecular sieve raw powder and binder kaolin are mixed at a mass ratio of 4:1 to obtain mixed raw powder. Using a pelletizing machine and its built-in powder adding and water spraying device, the powder is added while spraying water to complete the forming. Then, the pellets are sieved, polished and rolled to obtain wet pellets. They are then preheated at 450℃ for 20 minutes, and then calcined at 740℃ for 2 hours at a heating rate of 12℃ / min. After cooling, 3A molecular sieve with an average particle size of 2mm is obtained.

[0075] Comparative Example 4

[0076] The preparation steps of 3A molecular sieve are as follows:

[0077] In a powder mixer, 3A molecular sieve raw powder and binder kaolin are mixed at a mass ratio of 3:1 to obtain mixed raw powder. Using a pelletizing machine and its built-in powder adding and water spraying device, the powder is added while spraying water to complete the forming. Then, the pellets are sieved, polished and rolled to obtain wet pellets. They are then preheated at 450℃ for 20 minutes, and then calcined at 660℃ for 2 hours at a heating rate of 12℃ / min. After cooling, 3A molecular sieve with an average particle size of 2mm is obtained.

[0078] According to GB6287-86, the static water adsorption rate of 3A molecular sieves with high adsorption capacity prepared in Examples 1-6 and the 3A molecular sieves prepared in Comparative Examples 1-3 were tested at 10% humidity and 25℃. The results are shown in Table 1 and Table 2. Figure 1 As shown.

[0079] According to the HG / T 2783-1996 molecular sieve crushing resistance test method, the crushing resistance data of the 3A molecular sieves with high adsorption capacity prepared in Examples 1 to 6 and the 3A molecular sieves prepared in Comparative Examples 1 to 3 were tested respectively. The results are shown in Table 1.

[0080] Table 1. Static water adsorption rates of the 3A molecular sieves with high adsorption capacity prepared in Examples 1-6 and the 3A molecular sieves prepared in Comparative Examples 1-3.

[0081]

[0082]

[0083] Example 7

[0084] The 3A molecular sieve with high adsorption capacity was prepared according to the method of Example 1. The difference from Example 1 is that the heating rate in step (3) is 10℃ / min.

[0085] Example 8

[0086] The 3A molecular sieve with high adsorption capacity was prepared according to the method of Example 1. The difference from Example 1 is that the heating rate in step (3) is 8℃ / min.

[0087] Example 9

[0088] The 3A molecular sieve with high adsorption capacity was prepared according to the method of Example 1. The difference from Example 1 is that the calcination temperature in step (3) is 700°C.

[0089] Example 10

[0090] The 3A molecular sieve with high adsorption capacity was prepared according to the method of Example 1. The difference from Example 1 is that the calcination temperature in step (3) is 740°C.

[0091] Example 11

[0092] The 3A molecular sieve with high adsorption capacity was prepared according to the method of Example 1. The difference from Example 1 is that the calcination temperature in step (3) is 780°C.

[0093] In summary, compared with the comparative examples, the static water adsorption rate and strength of the 3A molecular sieves prepared by the method provided by the present invention in Examples 1-6 are significantly increased, indicating that the adsorption capacity and compressive strength of the 3A molecular sieves prepared in Examples 1-6 are significantly increased. At the same time, the present invention also measured the static water adsorption rate of the 3A molecular sieves prepared in Examples 7-11, and the test results were all greater than 25%, and the crushing force was all greater than 110N.

[0094] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a 3A molecular sieve with high adsorption capacity, characterized in that, Includes the following steps: (1) Mix the 3A molecular sieve raw powder with the molecular sieve raw powder material, then add the binder, and stir and first shape in sequence to obtain the core ball; The molecular sieve raw material is 4A molecular sieve raw powder and / or 5A molecular sieve raw powder; (2) Mix the 3A molecular sieve raw powder and the binder to obtain a mixed raw powder; The mixed raw powder is wrapped around the surface of the core sphere obtained in step (1), and a second molding process is performed to obtain a core sphere with a shell, also known as a wet sphere; In step (2), the ratio of the average diameter of the core sphere to the average thickness of the outer shell is (0.3~3):1; (3) The wet bulbs obtained in step (2) are preheated, calcined and cooled in sequence to obtain 3A molecular sieve with high adsorption capacity; The preheating temperature in step (3) is 400~600℃, and the preheating time is 10~40min.

2. The preparation method according to claim 1, characterized in that, In step (1), the mass ratio of 3A molecular sieve raw powder to molecular sieve raw powder material is 1:(1~6).

3. The preparation method according to claim 1, characterized in that, In step (1), the binder is clay, which is at least one of kaolin, sepiolite, palygorskite and bentonite.

4. The preparation method according to claim 1, characterized in that, In step (2), the mass ratio of 3A molecular sieve raw powder to binder is (3~5):

1.

5. The preparation method according to claim 1, characterized in that, The second forming process in step (2) also includes sieving, polishing and rounding in sequence.

6. The preparation method according to claim 1, characterized in that, The water content of the preheated product obtained in step (3) is 5~15wt%.

7. The preparation method according to claim 1, characterized in that, The heating rate of calcination in step (3) is 6~14℃ / min, the calcination temperature is 600~780℃, and the calcination time is 1~3h.

8. The 3A molecular sieve with high adsorption capacity prepared by the preparation method according to any one of claims 1 to 7.

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