13X molecular sieve and preparation method thereof

Abstract

The invention belongs to the technical field of nonmetallic mineral materials and artificially synthesized zeolites, and particularly relates to a 13X molecular sieve and a preparation method thereof.The preparation method comprises the following steps that low-grade natural protein soil is subjected to ball milling, and protein soil powder is obtained; mixing the protein soil powder with sodium hydroxide, roasting, activating, cooling, and grinding to obtain activated protein soil; leaching the activated protein soil, and filtering to obtain filtrate containing silicon and aluminum species; the method comprises the following steps: adding a supplementary aluminum source into a filtrate containing silicon and aluminum species to obtain a mixed solution, carrying out a crystallization hydrothermal reaction on the mixed solution, and carrying out suction filtration and drying on the product to obtain the 13X molecular sieve, the molecular sieve prepared by the method has a diameter of 0.6-1.5 [mu] m and a specific surface area of more than 600 m < 2 > / g, and has high crystallinity and purity. The method has the advantages of simple preparation process, low cost, excellent product performance and small environmental harm, and effectively realizes high-value utilization of the low-grade protein soil.

Description

Technical Field

[0001] The invention belongs to the technical field of non-metallic mineral materials and artificially synthesized zeolites, and specifically relates to a 13X molecular sieve and a preparation method thereof. Background Art

[0002] Zeolite molecular sieve is a hydrated crystalline aluminosilicate compound with uniform pores, which has a wide range of applications in many fields. Its unique pore structure, large specific surface area, good hydrothermal stability and ion exchange properties make it an important material in the fields of catalysts, adsorbents, etc. 13X molecular sieve, also known as NaX type molecular sieve, belongs to the cubic crystal system and has a FAU type topological structure. Its pore size is suitable for adsorbing small molecules, making it suitable for a variety of applications, such as drying of medicine and air compression systems, and as a catalyst carrier. However, the reserves of natural molecular sieves in nature are scarce, and their performance cannot meet the requirements of industrial applications. Industrially produced molecular sieves generally use chemical raw materials such as sodium hydroxide, aluminum hydroxide, sodium silicate, sodium aluminate, etc., which require a lot of energy consumption, have high production costs and are prone to secondary pollution.

[0003] Natural non-metallic mineral resources are abundant and inexpensive, so they have become low-cost, green alternative raw materials for the synthesis of zeolite molecular sieves. In recent years, some scholars have used natural minerals or solid wastes such as potassium feldspar, diatomaceous earth, fly ash and coal gangue as silicon sources or aluminum sources to prepare 13X molecular sieves. However, the existing 13X molecular sieve synthesis methods and processes generally have low resource utilization efficiency. Due to differences in raw material properties, it is difficult to accurately control key parameters such as the silicon-aluminum ratio, resulting in unstable crystallinity of the synthesized 13X molecular sieve, low product purity and crystallinity; and the process is complex, the production cost is high, a large amount of residues are generated during the production process that are difficult to handle, and a large amount of secondary pollutants are discharged. Summary of the invention

[0004] In view of the deficiencies of the above-mentioned prior art, the object of the present invention is to provide a 13X molecular sieve and a preparation method thereof. The present invention utilizes low-grade natural protein soil as a raw material and adds a small amount of sodium aluminate as a supplementary aluminum source to prepare the 13X molecular sieve, and adopts a one-step hydrothermal method to synthesize the 13X molecular sieve, thereby realizing high-value utilization of low-grade protein soil resources.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions: A method for preparing 13X molecular sieve comprises the following steps: The low-grade natural protein clay is ball-milled to obtain protein clay powder.

[0006] The protein soil powder is mixed with sodium hydroxide and calcined to activate the protein soil, and then ground after cooling to obtain activated protein soil.

[0007] The activated protein soil is leached, and the sodium silicate converted after calcination is leached from the calcined product, silicon and aluminum species are dissolved and released, and a filtrate containing silicon and aluminum species is obtained by filtration.

[0008] A supplementary aluminum source is added to the filtrate containing silicon and aluminum species to obtain a mixed solution, and the mixed solution is subjected to a hydrothermal crystallization reaction. The silicon and aluminum species and the supplementary aluminum source form a sodium aluminosilicate gel. The basic structural units in the sodium aluminosilicate gel are connected in an orderly manner to obtain a 13X molecular sieve.

[0009] The present invention uses low-grade natural protein soil as a raw material, mixes and calcines it with sodium hydroxide after ball milling, activates the protein soil, and extracts the activated protein soil. Sodium silicate converted after calcination is extracted from the calcined product, silicon and aluminum species are dissolved and released, and a filtrate containing silicon and aluminum species is obtained by filtration. Then, an aluminum source is added to the filtrate containing silicon and aluminum species, and the ratio of SiO2 and Al2O3 in the hydrothermal reaction raw materials is accurately controlled to ensure the purity and high crystallinity of the prepared 13X molecular sieve. Finally, a crystallization hydrothermal reaction is performed, and the silicon, aluminum species and the supplemented aluminum source form a sodium aluminosilicate gel. Basic structural units such as four-membered rings, six-membered rings and beta cages appear in the gel. These basic structural units are connected in an orderly manner to obtain a 13X molecular sieve. The present invention realizes the comprehensive utilization of low-grade natural protein soil, effectively improves the added value of natural protein soil, and reduces the manufacturing cost of the 13X molecular sieve.

[0010] In a preferred embodiment of the present invention, in the mixed solution, the molar ratio of Na2O, Al2O3, SiO2 and H2O is 1~4:1:2~8:150~300.

[0011] In a preferred embodiment of the present invention, the mass ratio of protein soil powder to sodium hydroxide is 1:1-1.5.

[0012] In a preferred embodiment of the present invention, the leaching solvent is water, and the mass ratio of the activated protein soil to water is 1:15-20.

[0013] In a preferred embodiment of the present invention, the crystallization hydrothermal reaction temperature is 80° C. to 100° C., and the crystallization hydrothermal reaction time is 6 h to 24 h.

[0014] In a preferred embodiment of the present invention, the leaching temperature is 60°C to 90°C, and the leaching time is 2 h to 4 h.

[0015] In a preferred embodiment of the present invention, the calcination temperature is 600° C. to 900° C., and the calcination time is 1 h to 5 h.

[0016] In a preferred embodiment of the present invention, the drying temperature is 100° C. to 150° C., and the drying time is 6 h to 12 h.

[0017] In a preferred embodiment of the present invention, the whiteness of the low-grade natural protein clay ore powder is ≤50%, the sum of the mass percentages of SiO2 and Al2O3 is greater than 80%, the mass percentage of Fe2O3 is 2%~5%, and the particle size is ≥100 mesh.

[0018] Another object of the present invention is to provide a 13X molecular sieve prepared by any of the preparation methods described above.

[0019] In a preferred embodiment of the present invention, the 13X molecular sieve has a diameter of 0.6 μm to 1.5 μm and a specific surface area of ​​712.3 m 2 / g~912.6 m 2 / g.

[0020] Natural protein clay is a low-cost, abundant siliceous sedimentary rock. Its main components are amorphous hydrated silicon dioxide (SiO2·nH2O) and a small amount of other metal oxides such as Fe2O3, MgO, CaO, K2O, Na2O, etc., of which the SiO2 content is about 70% and the Al2O3 content is about 15%. It is suitable for the synthesis of 13X molecular sieve.

[0021] my country has a large number of medium- and low-grade natural protein soil resources that have not been effectively utilized. Therefore, using low-grade natural protein soil as raw material to prepare 13X molecular sieve can not only reduce the synthesis cost, but also has important significance for the high-value utilization of protein soil resources and environmental protection.

[0022] Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention uses low-grade natural protein soil as raw material, mixes and calcines with sodium hydroxide after ball milling, activates the protein soil, and extracts the activated protein soil. Sodium silicate converted after calcination is extracted from the calcined product, dissolves and releases silicon and aluminum species, and obtains a filtrate containing silicon and aluminum species after filtration. Then, an aluminum source is added to the filtrate containing silicon and aluminum species, and the ratio of SiO2 and Al2O3 in the hydrothermal reaction raw materials is accurately controlled to ensure the purity and high crystallinity of the prepared 13X molecular sieve. Finally, a crystallization hydrothermal reaction is performed, and the silicon and aluminum species are reacted with the supplemented aluminum source. Sodium aluminosilicate gel is formed, and basic structural units such as four-membered rings, six-membered rings and beta cages appear in the gel. These basic structural units are connected in order to obtain 13X molecular sieve. The present invention realizes the comprehensive utilization of low-grade natural protein soil, effectively improves the added value of natural protein soil, and reduces the manufacturing cost of 13X molecular sieve. A simple one-step hydrothermal method is used in the synthesis process, and pollutant emissions are small. The preparation process is simple, the cost is low, the product performance is excellent, and the environmental hazard is small. The high-value utilization of low-grade protein soil is effectively realized, and industrial production can be realized.

[0023] 2. The molecular sieve prepared by this method has a diameter of 0.6 μm~1.5 μm and a specific surface area of ​​more than 600 m 2 / g, with high crystallinity and purity. The present invention adopts the method of mixing protein soil with sodium hydroxide for roasting and then leaching to extract silicon source, and then adding aluminum source, so as to facilitate the precise control of the proportion of each component in the hydrothermal reaction raw material, so the prepared molecular sieve has a large specific surface area, high crystallinity and purity. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The XRD pattern of the natural protein soil used in the present invention.

[0025] Figure 2 This is the XRD pattern of the 13X molecular sieve synthesized in Example 1 of the present invention.

[0026] Figure 3 This is a scanning electron microscope image of the 13X molecular sieve synthesized in Example 2 of the present invention.

[0027] Figure 4 This is a scanning electron microscope image of the 13X molecular sieve synthesized in Example 3 of the present invention. DETAILED DESCRIPTION

[0028] The following is a detailed description of the technical solutions in the embodiments of the present invention in combination with the preferred embodiments and the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] It should be noted that all professional terms used in the present invention are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention. Unless otherwise specifically stated, various raw materials, reagents, instruments and equipment used in the following embodiments of the present invention can be purchased from the market or prepared by existing methods.

[0030] The natural protein soil samples used in the embodiments of the present invention are from low-grade protein soil in the Nenjiang area of ​​Heilongjiang Province. The chemical composition thereof is determined by XRF as shown in Table 1, wherein the total content of SiO2 and Al2O3 is greater than 80%. The X-ray diffraction pattern of natural protein soil is shown in Table 1. Figure 1 It can be seen that in addition to amorphous silicon, the rest are mainly cristobalite and quartz, accompanied by a small amount of kaolin, magnetite and other minerals.

[0031] Table 1 Chemical composition of protein soil samples Example 1 A method for preparing 13X molecular sieve comprises the following steps: (1) Low-grade natural protein clay is ball-milled to obtain protein clay powder with a particle size of 200 mesh sieve residue ≤ 3%.

[0032] (2) Weigh protein clay powder and solid sodium hydroxide in a mass ratio of 1:1.2, mix them evenly, and place them in a muffle furnace for calcination at 600 °C for 3 h. After cooling, grind them into powder to obtain activated protein clay.

[0033] (3) The activated protein soil and water are added into a soaking tank at a liquid-to-solid mass ratio of 20:1 for leaching for 2 hours at a leaching temperature of 70°C. The sodium silicate converted after calcination in step (2) is leached from the calcined product, and then filtered to obtain a filtrate, and the contents of SiO2 and Al2O3 in the filtrate are determined.

[0034] (4) The filtrate obtained in step (3) is placed in a hydrothermal reactor with polytetrafluoroethylene, and a certain amount of sodium aluminate is added to supplement the aluminum source, wherein the molar ratio of the components in the filtrate is: n(Na2O):n(Al2O3):n(SiO2):n(H2O)=2:1:3:180. The reactor is subjected to a crystallization reaction at 90°C for 6 h. After the reaction is completed, the reaction is cooled to room temperature, the product is filtered, and dried at 105°C for 12 h to obtain a 13X molecular sieve having a diameter of 0.54 μm and a specific surface area of ​​712.3 m 2 / g.

[0035] Example 2 A method for preparing 13X molecular sieve comprises the following steps: (1) Low-grade natural protein clay is ball-milled to obtain protein clay powder with a particle size of 200 mesh and a residue of ≤3%.

[0036] (2) Low-grade natural protein clay and solid sodium hydroxide were weighed in a mass ratio of 1:1.4, mixed evenly, and calcined in a muffle furnace at 700 °C for 3 h. After cooling, the mixture was ground into powder to obtain activated protein clay.

[0037] (3) The activated protein soil is added to a soaking tank at a liquid-to-solid ratio of 18:1 for leaching for 2 hours at a leaching temperature of 80°C. The sodium silicate converted after calcination in step (2) is leached from the calcined product, and then filtered to obtain a filtrate, and the contents of SiO2 and Al2O3 in the filtrate are determined.

[0038] (4) The filtrate obtained in step (3) is placed in a hydrothermal reactor with polytetrafluoroethylene, and a certain amount of sodium aluminate is added to supplement the aluminum source, wherein the molar ratio of the components in the filtrate is: n(Na2O):n(Al2O3):n(SiO2):n(H2O)=3:1:5:220. The reactor is subjected to a crystallization reaction at 95°C for 12 h. After the reaction is completed, the reaction is cooled to room temperature, the product is filtered, and dried at 120°C for 8 h to obtain a 13X molecular sieve having a diameter of 1.14 μm and a specific surface area of ​​850.7 m 2 / g.

[0039] Example 3 A method for preparing 13X molecular sieve comprises the following steps: (1) Low-grade natural protein clay is ball-milled to obtain protein clay powder with a particle size of 200 mesh and a residue of ≤3%.

[0040] (2) Low-grade natural protein clay and solid sodium hydroxide were weighed in a mass ratio of 1:1.5, mixed evenly, and calcined in a muffle furnace at 800 °C for 1 h. After cooling, the mixture was ground into powder to obtain activated protein clay.

[0041] (3) The activated protein soil is added to a soaking tank at a liquid-to-solid ratio of 19:1 for leaching for 3 hours at a leaching temperature of 80°C. The sodium silicate converted after calcination in step (2) is leached from the calcined product, and then filtered to obtain a filtrate, and the contents of SiO2 and Al2O3 in the filtrate are determined.

[0042] (4) The filtrate obtained in step (3) is placed in a hydrothermal reactor with polytetrafluoroethylene, and a certain amount of sodium aluminate is added to supplement the aluminum source, wherein the molar ratio of the components in the filtrate is: n(Na2O):n(Al2O3):n(SiO2):n(H2O)=3.5:1:6:260. The reactor is subjected to crystallization reaction at 85°C for 18 h. After the reaction is completed, the reaction is cooled to room temperature, the product is filtered, and dried at 105°C for 10 h to obtain a 13X molecular sieve having a diameter of 0.76 μm and a specific surface area of ​​912.6 m 2 / g.

[0043] Example 4 A method for preparing 13X molecular sieve comprises the following steps: (1) Low-grade natural protein clay is ball-milled to obtain protein clay powder with a particle size of 200 mesh and a residue of ≤3%.

[0044] (2) Low-grade natural protein clay and solid sodium hydroxide were weighed in a mass ratio of 1:1, mixed evenly, and calcined in a muffle furnace at 900 °C for 1 h. After cooling, the mixture was ground into powder to obtain activated protein clay.

[0045] (3) The activated protein soil is added to a soaking tank at a liquid-to-solid ratio of 15:1 for leaching for 4 hours at a leaching temperature of 60°C. The sodium silicate converted after calcination in step (2) is leached from the calcined product, and then filtered to obtain a filtrate, and the contents of SiO2 and Al2O3 in the filtrate are determined.

[0046] (4) The filtrate obtained in step (3) is placed in a hydrothermal reactor with polytetrafluoroethylene, and a certain amount of sodium aluminate is added to supplement the aluminum source, wherein the molar ratio of the components in the filtrate is: n(Na2O):n(Al2O3):n(SiO2):n(H2O)=1:1:2:150. The reactor is subjected to crystallization reaction at 80°C for 24 h. After the reaction is completed, it is cooled to room temperature, the product is filtered, and dried at 105°C for 10 h to obtain 13X molecular sieve.

[0047] Example 5 A method for preparing 13X molecular sieve comprises the following steps: (1) Low-grade natural protein clay is ball-milled to obtain protein clay powder with a particle size of 200 mesh and a residue of ≤3%.

[0048] (2) Low-grade natural protein clay and solid sodium hydroxide were weighed in a mass ratio of 1:1.2, mixed evenly, and placed in a muffle furnace for calcination at 600 °C for 5 h. After cooling, the mixture was ground into powder to obtain activated protein clay.

[0049] (3) The activated protein soil is added to a soaking tank at a liquid-to-solid ratio of 20:1 for leaching for 3 hours at a leaching temperature of 90°C. The sodium silicate converted after calcination in step (2) is leached from the calcined product, and then filtered to obtain a filtrate, and the contents of SiO2 and Al2O3 in the filtrate are determined.

[0050] (4) The filtrate obtained in step (3) is placed in a hydrothermal reactor with polytetrafluoroethylene, and a certain amount of sodium aluminate is added to supplement the aluminum source, wherein the molar ratio of the components in the filtrate is: n(Na2O):n(Al2O3):n(SiO2):n(H2O)=4:1:8:300. The reactor is subjected to crystallization reaction at 100°C for 16 h. After the reaction is completed, it is cooled to room temperature, the product is filtered, and dried at 105°C for 10 h to obtain 13X molecular sieve.

[0051] Results Analysis Figure 2 From the XRD spectrum of the 13X molecular sieve synthesized in Example 1 of the present invention, it can be seen that the molecular sieve prepared by the preparation method of the 13X molecular sieve provided by the present invention has a high degree of crystallinity, and the obtained product has a high purity and can be clearly seen to be a typical 13X structure.

[0052] Figure 3 The scanning electron microscope image of the 13X molecular sieve synthesized in Example 2 of the present invention shows that the molecular sieve prepared in Example 2 of the present invention has a particle diameter of about 2 um to 3 um and a uniform particle size distribution. The results show that the prepared molecular sieve has good crystallinity and uniformity.

[0053] Figure 4 This is a scanning electron microscope image of the 13X molecular sieve synthesized in Example 3 of the present invention. It can be seen that the 13X molecular sieve prepared in Example 3 of the present invention has molecular sieve grains with obvious cubic shape, and its structure is regular and the shape is relatively good, indicating that the prepared molecular sieve has a high degree of crystallinity.

[0054] In summary, the present invention uses low-grade natural protein soil as raw material, mixes and calcined with sodium hydroxide after ball milling, activates the protein soil, and extracts the activated protein soil. The sodium silicate converted after calcination is leached from the calcined product, dissolves and releases silicon and aluminum species, and obtains a filtrate containing silicon and aluminum species after filtration. Then, an aluminum source is added to the filtrate containing silicon and aluminum species, and the ratio of SiO2 and Al2O3 in the hydrothermal reaction raw materials is accurately controlled to ensure the purity and high crystallinity of the prepared 13X molecular sieve. Finally, a crystallization hydrothermal reaction is carried out, and the silicon, aluminum species and the supplemented aluminum source form a sodium aluminosilicate gel. Basic structural units such as four-membered rings, six-membered rings and β cages appear in the gel. These basic structural units are connected in an orderly manner to obtain a 13X molecular sieve. The present invention realizes the comprehensive utilization of low-grade natural protein soil, effectively improves the added value of natural protein soil, and reduces the manufacturing cost of 13X molecular sieve.

[0055] It should be noted that when the present invention involves a numerical range, it should be understood that the two endpoints of each numerical range and any value between the two endpoints can be selected. Since the steps and methods used are the same as those in the embodiments, in order to avoid redundancy, the present invention describes a preferred embodiment. Although the preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they know the basic creative concept. Therefore, the attached claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0056] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the protection scope of the present invention and its equivalent technology, the present invention is also intended to include these changes and variations.

Claims

1. A method for preparing 13X molecular sieve, characterized in that: The following steps are involved: Ball-milling low-grade natural protein clay to obtain protein clay powder; The protein soil powder is mixed with sodium hydroxide and calcined to activate the protein soil powder, and then ground after cooling to obtain activated protein soil; Leaching the activated protein soil, leaching the sodium silicate converted after calcination from the calcined product, dissolving and releasing silicon and aluminum species, and filtering to obtain a filtrate containing silicon and aluminum species; A supplementary aluminum source is added to the filtrate containing silicon and aluminum species to obtain a mixed solution, and the mixed solution is subjected to a crystallization hydrothermal reaction. The silicon and aluminum species and the supplementary aluminum source form a sodium aluminosilicate gel. The basic structural units in the sodium aluminosilicate gel are connected in an orderly manner to obtain a 13X molecular sieve.

2. The method for preparing 13X molecular sieve according to claim 1, characterized in that: In the mixed solution, the molar ratio of Na2O, Al2O3, SiO2 and H2O is 1~4:1:2~8:150~300.

3. The method for preparing 13X molecular sieve according to claim 1, characterized in that: The mass ratio of protein soil powder to sodium hydroxide is 1:1~1.

5.

4. The method for preparing 13X molecular sieve according to claim 1, characterized in that: The leaching solvent is water, and the mass ratio of the activated protein soil to water is 1:15~20.

5. The method for preparing 13X molecular sieve according to claim 1, characterized in that: The crystallization hydrothermal reaction temperature is 80°C~100°C, and the crystallization hydrothermal reaction time is 6 h~24 h.

6. The method for preparing 13X molecular sieve according to claim 1, characterized in that: The immersion temperature is 60℃~90℃, and the immersion time is 2 h~4 h.

7. The method for preparing 13X molecular sieve according to claim 1, characterized in that: The calcination temperature is 600℃~900℃, and the calcination time is 1 h~5 h.

8. The method for preparing 13X molecular sieve according to claim 1, characterized in that: The whiteness of low-grade natural protein clay ore powder is ≤50%, the sum of the mass percentages of SiO2 and Al2O3 is greater than 80%, the mass percentage of Fe2O3 is 2%~5%, and the particle size is ≥100 mesh.

9. A 13X molecular sieve prepared by the preparation method according to any one of claims 1 to 8.

10. The 13X molecular sieve according to claim 9, characterized in that: The 13X molecular sieve has a diameter of 0.6 μm to 1.5 μm and a specific surface area of ​​712.3 m 2 / g~912.6 m 2 / g.

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