FAU type aluminum phosphate-based molecular sieve and preparation method thereof
By preparing FAU-type aluminum phosphate-based molecular sieves doped with heteroatoms such as Si, Co, Zn, and Ga, the problems of low crystallinity and low product yield in the existing synthesis method are solved, and the efficient preparation of high-crystallinity and hydrothermally stable molecular sieves is achieved, expanding its application range.
Patent Information
- Application Number
- CN202510961396.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-11
- Publication Date
- 2025-10-10
AI Technical Summary
The existing SAPO-37 synthesis method has problems such as low crystallinity and low product yield, and there is little research on heteroatom-doped FAU-type aluminum phosphate-based molecular sieves, which limits its application range.
Aluminum phosphate dry gel was used as a precursor, and FAU-type aluminum phosphate-based molecular sieves doped with heteroatoms such as Si, Co, Zn, and Ga were prepared in a closed system by a heating crystallization method. Organic amine solution was used as a template, and the synthesis conditions were optimized to improve the crystallinity and hydrothermal stability.
The FAU-type aluminum phosphate-based molecular sieve with high crystallinity, adjustable framework acidity and excellent hydrothermal stability was prepared, which enriched the types of molecular sieves, reduced the synthesis cost and improved the synthesis efficiency.
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Figure CN120757127A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of molecular sieve preparation, in particular to a FAU type aluminum phosphate-based molecular sieve and a preparation method thereof. Background Art
[0002] In the 1980s, scientists such as Wilson ST and Flanigen EM of UCC successfully developed another important member of the molecular sieve family - aluminum phosphate molecular sieve (AlPO4-n), which attracted much attention due to its stable skeleton structure and moderate hydrophilicity. However, the strict alternating arrangement of AlO4 and PO4 tetrahedrons in its skeleton resulted in the overall electrical neutrality of the material, which lacked ion exchange capacity and strong acid sites. These characteristics limited its practical application range. By introducing heteroatoms, the performance of aluminum phosphate molecular sieve can be effectively regulated, giving it the ability to maintain its original advantages while also enhancing its hydrophilicity. Acidity, which significantly expands the application prospects of this type of materials in catalysis, photoelectricity, selective adsorption and ion exchange.
[0003] In the synthesis and application of molecular sieves, molecular sieves with the same topological structure are composed of different elements. This phenomenon is very common. For example, SAPO-34 (silicoaluminophosphate molecular sieve) and SSZ-13 (silicoaluminophosphate molecular sieve) both have CHA topological structures; ZSM-5 (silicoaluminophosphate molecular sieve), TS-1 (titanium silicate molecular sieve) and Silicalite-1 (pure silicon molecular sieve) have the same MFI topological structure; while X-type zeolite, Y-type zeolite (silicoaluminophosphate molecular sieve) and SAPO-37 (silicoaluminophosphate molecular sieve) have the same FAU configuration. The different elemental compositions of molecular sieves further reflect their different physical and chemical properties and applications.
[0004] FAU-type molecular sieves are highly crystalline, microporous materials with a three-dimensional network consisting of tetrahedrally coordinated T atoms (T = Al, P, or Si) forming sodalite cages (SOD) connected by double six-rings (d6r: two rings of six T atoms). The three-dimensional arrangement of SOD forms a large 12-membered ring. Currently, FAU-type X and Y zeolites are primarily used in catalytic cracking reactions. However, heteroatom-substituted FAU-type aluminum phosphate-based molecular sieves (SAPO-37) have a wide range of applications due to their suitable acidity, high crystalline structure, large pore size, and high surface area. They are key materials in processes such as n-decane isomerization, isobutylene / 2-butene alkylation, o-xylene isomerization, and as gas adsorbents.
[0005] Currently, the traditional hydrothermal synthesis method is still the mainstream method for synthesizing three-dimensional macroporous silicoaluminophosphate-based molecular sieves such as SAPO-37, but it suffers from problems such as low crystallinity and low product yield. In recent years, researchers have begun to explore improved synthesis methods. At the same time, research on FAU-type aluminum phosphate-based molecular sieves doped with other heteroatoms (such as Co, Zn, Ga, etc.) is still relatively limited, indicating that there is still considerable research space in optimizing synthesis methods and developing new molecular sieves. Summary of the Invention
[0006] The purpose of the present invention is to provide a FAU type aluminum phosphate-based molecular sieve and a preparation method thereof, which can be used to prepare FAU structure molecular sieves doped with heteroatoms such as Si, Co, Zn, and Ga. The prepared aluminum phosphate-based molecular sieve has high crystallinity, adjustable acidity of the skeleton, and excellent hydrothermal stability.
[0007] To achieve the above object, the present invention provides a method for preparing a FAU type aluminum phosphate-based molecular sieve, comprising the following steps:
[0008] S1. Preparation of aluminum phosphate xerogel: adding an aluminum source and phosphoric acid to deionized water in sequence, stirring at room temperature, and drying to obtain a highly uniform aluminum phosphate xerogel;
[0009] S2. Preparing dry gel powder: Grind and thoroughly mix the aluminum phosphate dry gel and heteroatom obtained in S1 to obtain dry gel powder;
[0010] S3. Preparation of FAU type aluminum phosphate-based molecular sieve: The dry gel powder obtained in S2 is immersed in an organic amine solution to obtain a mixture, the mixture is heated and crystallized, and the solid product obtained by crystallization is washed with water, centrifuged, dried, and calcined to obtain a FAU type aluminum phosphate-based molecular sieve.
[0011] Preferably, in S1, the aluminum source is one of pseudo-boehmite, aluminum chloride, and aluminum isopropoxide; and the concentration of phosphoric acid is 20 wt% to 99 wt%.
[0012] Preferably, in S1, the molar ratio of Al2O3, P2O5, and H2O in the aluminum phosphate dry gel is 1:(0.1-5):(0.01-5).
[0013] Preferably, in S1, the stirring speed is 400-600 r / min, and the stirring time is 1-24 h;
[0014] The drying temperature is 60-120℃ and the drying time is 2-12h.
[0015] Preferably, in S2, the heteroatom is one or more of a silicon source, a cobalt source, a zinc source, and a gallium source;
[0016] The silicon source is one of white carbon black, ethyl orthosilicate, and silica sol; the cobalt source is one of cobalt acetate, cobalt sulfate, cobalt nitrate, and cobalt chloride; the zinc source is one of zinc acetate, zinc nitrate, zinc sulfate, and zinc chloride; and the gallium source is one of gallium oxide, gallium chloride, and gallium nitrate.
[0017] Preferably, in S3, the organic amine solution is one or more of tetrapropylammonium hydroxide solution and tetramethylammonium hydroxide solution.
[0018] Preferably, in S3, the concentration of tetrapropylammonium hydroxide in the tetrapropylammonium hydroxide solution is 5 wt% to 90 wt%; the concentration of tetramethylammonium hydroxide in the tetramethylammonium hydroxide solution is 5 wt% to 80 wt%.
[0019] Preferably, in S3, the molar ratio of Al2O3, P2O5, tetrapropylammonium hydroxide, tetramethylammonium hydroxide and H2O in the mixture is 1:(0.1-5):(0.1-10):(0.001-5):(0.01-40).
[0020] Preferably, in S3, the temperature for heating and crystallization is 120-250° C., and the time for heating and crystallization is 2-120 h;
[0021] The drying temperature is 20-120℃ and the drying time is 1-24h;
[0022] The calcination temperature is 300-600°C, and the calcination time is 2-12h.
[0023] The present invention also provides a FAU type aluminum phosphate-based molecular sieve, which is prepared using the above-mentioned method for preparing a FAU type aluminum phosphate-based molecular sieve.
[0024] Therefore, the present invention adopts the above-mentioned FAU type aluminum phosphate-based molecular sieve and its preparation method, which has the following beneficial effects:
[0025] (1) Using highly uniform aluminum phosphate-based xerogel as a precursor, aluminum phosphate-based molecular sieves can be synthesized by heating in a closed system to prepare FAU-type molecular sieves substituted with heteroatoms such as Si, Co, Zn, and Ga, enriching the types of FAU-type aluminum phosphate-based molecular sieves;
[0026] (2) This method optimizes the existing synthesis conditions, saves synthesis costs, and improves synthesis efficiency. The prepared aluminum phosphate-based molecular sieve has high crystallinity, excellent hydrothermal stability, and adjustable acidity of the skeleton.
[0027] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS
[0028] Figure 1is the XRD pattern of SAPO-37 prepared in Example 1 of the FAU-type aluminum phosphate-based molecular sieve and the preparation method thereof.
[0029] Figure 2 is the SEM pattern of SAPO-37 prepared in Example 1 of the FAU-type aluminum phosphate-based molecular sieve and the preparation method thereof.
[0030] Figure 3 is the physical adsorption isotherm of SAPO-37 prepared in Example 1 of the FAU-type aluminum phosphate-based molecular sieve and the preparation method thereof after removal of the template by calcination.
[0031] Figure 4 is the NH3-TPD characterization of SAPO-37 prepared in Example 1 of the FAU-type aluminum phosphate-based molecular sieve and the preparation method thereof. DETAILED DESCRIPTION
[0032] The technical solutions of the present application are further described below through the drawings and examples.
[0033] Unless otherwise defined, the technical terms or scientific terms used in the present application shall have the usual meanings understood by those skilled in the art to which the present application belongs.
[0034] Example 1
[0035] A silicon-doped FAU-type aluminum phosphate-based molecular sieve, and a preparation method thereof, comprising the following steps:
[0036] S1, preparing an aluminum phosphate xerogel: 2.20 g of aluminum chloride, 1.30 g of phosphoric acid (85 wt%) were sequentially added to 18 g of deionized water, and stirred uniformly at a rotation speed of 550 r / min at room temperature, then ice-bath was performed, and when the water bath pot temperature showed 5℃, 8.0 mL of propylene oxide (PO) was added dropwise to obtain a hydrogel, the obtained hydrogel was dried at 90℃ for 2 h, then transferred to a culture dish and dried at 120℃ for 4 h to obtain a highly uniform aluminum phosphate xerogel.
[0037] S2, preparing a dry gel powder: the aluminum phosphate xerogel obtained in S1 and 0.24 g of tetraethyl orthosilicate were transferred to a mortar, and fully mixed by grinding to obtain a dry gel powder.
[0038] S3. Preparation of FAU-type aluminum phosphate molecular sieve: The dry gel powder obtained in S2 was transferred to an autoclave and immersed in 1.8 g of tetrapropylammonium hydroxide (TPAOH) solution (40 wt%) and 0.05 g of tetramethylammonium hydroxide (TMAOH) solution (25 wt%) to form a homogeneous mixture. The molar ratio of SiO2, Al2O3, P2O5, TPAOH, TMAOH, and H2O in the resulting mixture was 1.1:1.0:1.2:2.0:0.2:40. The mixture was heated for crystallization, i.e., reacted at 190°C for 36 h. The solid product obtained by crystallization was thoroughly washed with water and centrifuged at 7000 rpm for 15 min. The separated precipitate was then dried in an oven at 110°C for 6 h and then calcined at 500°C in an air atmosphere for 12 h to obtain a FAU-type aluminum silicophosphate molecular sieve, designated SAPO-37.
[0039] The SAPO-37 prepared in Example 1 was subjected to XRD test, and the results were as follows: Figure 1 As shown in FIG. 1 , the characteristic peaks are located at 2θ=6.22°, 10.14°, 11.89°, 12.42°, 15.64°, 18.65°, 20.32°, 22.74°, and 23.59°. These characteristic peaks confirm that the sample belongs to the SAPO-37 molecular sieve of FAU configuration. The SAPO-37 prepared in Example 1 was subjected to SEM test, and the results are shown in FIG. Figure 2 As shown in the figure, the obtained product is a submicron crystal with a smooth surface and uniform particle size, rather than a classic octahedral morphology. This is because the introduction of propylene oxide promotes the homogenization of the gel. As an additive, propylene oxide can adjust the pH value and viscosity of the gel, thereby affecting the formation and growth dynamics of the crystal nucleus, and ultimately leading to a reduction in grain size. Figure 3 As shown in the figure, the results of N2 physical adsorption show that SAPO-37 after removing the template has micropore filling and mesopores generated by the accumulation between particles, and its BET specific surface area is 656m 2 / g, micropore specific surface area is 235m 2 / g, and the mesopore volume is 0.48cm 3 / g, further confirming its good crystallinity. Figure 4 ) showed that the product had two acidity distributions between 100-350 °C and 350-700 °C, corresponding to weak acid and medium-strong acid, respectively, which confirmed that the acidity of SAPO-37 has adjustable skeleton.
[0040] Example 2
[0041] A silicon-doped FAU type aluminum phosphate-based molecular sieve, the preparation method of which comprises the following steps:
[0042] S1, preparation of aluminum phosphate xerogel: 2.20 g of aluminum chloride, 1.30 g of phosphoric acid (85 wt%) were sequentially added into 18 g of deionized water, which was stirred uniformly at a rotation speed of 550 r / min at room temperature, and then was subjected to ice bath. When the temperature of the water bath showed 5 °C, 8.0 mL of PO was added dropwise to obtain a hydrogel. The obtained hydrogel was dried at 110 °C for 2 h, and then was transferred to a culture dish for drying at 120 °C for 4 h to obtain a highly uniform aluminum phosphate xerogel.
[0043] S2, preparation of dry gel powder: the aluminum phosphate xerogel obtained in S1 and 0.14 g of white carbon black were transferred to a mortar, and were mixed by grinding to obtain a dry gel powder.
[0044] S3, preparation of FAU-type aluminum phosphate-based molecular sieve: the dry gel powder obtained in S2 was transferred to a high-pressure reaction kettle, and was immersed in 1.2 g of TPAOH solution (40 wt%) and 0.02 g of TMAOH solution (25 wt%) to form a uniform mixture. The molar ratio of SiO2, Al2O3, P2O5, TPAOH, TMAOH and H2O in the obtained mixture was 0.5:1.0:1.1:2.0:0.2:36. The mixture was subjected to heating crystallization, i.e., was reacted at 200 °C for 36 h. The solid product obtained by crystallization was subjected to sufficient water washing, centrifugation at 7000 r / min for 10 min, and then the precipitate separated was dried in an oven at 120 °C for 4 h, and was calcined at 500 °C for 12 h in an air atmosphere to obtain a FAU-type silico-aluminum phosphate molecular sieve.
[0045] Example 3
[0046] A silicon-doped FAU-type aluminum phosphate-based molecular sieve, a preparation method thereof comprises the following steps:
[0047] S1, preparation of aluminum phosphate xerogel: 2.20 g of aluminum chloride, 1.30 g of phosphoric acid (85 wt%) were sequentially added into 18 g of deionized water, which was stirred uniformly at a rotation speed of 550 r / min at room temperature, and then was subjected to ice bath. When the temperature of the water bath showed 5 °C, 8.0 mL of PO was added dropwise to obtain a hydrogel. The obtained hydrogel was dried at 110 °C for 2 h, and then was transferred to a culture dish for drying at 120 °C for 4 h to obtain a highly uniform aluminum phosphate xerogel.
[0048] S2, preparation of dry gel powder: the aluminum phosphate xerogel obtained in S1 and 0.14 g of white carbon black were transferred to a mortar, and were mixed by grinding to obtain a dry gel powder.
[0049] S3. Preparation of FAU-type aluminum phosphate molecular sieve: The dry gel powder obtained in S2 was transferred to an autoclave and immersed in 0.8 g of TPAOH solution (40 wt%) and 0.05 g of TMAOH solution (25 wt%) to form a homogeneous mixture. The molar ratio of SiO2, Al2O3, P2O5, TPAOH, TMAOH, and H2O in the resulting mixture was 0.4:1.0:1.5:1.6:0.2:40. The mixture was heated for crystallization at 200°C for 48 h. The crystallized solid product was thoroughly washed with water and centrifuged at 7000 rpm for 10 min. The separated precipitate was then dried in an oven at 120°C for 4 h and then calcined at 500°C in air for 12 h to obtain the FAU-type aluminum silicophosphate molecular sieve.
[0050] Example 4
[0051] A silicon-doped FAU type aluminum phosphate-based molecular sieve, the preparation method of which comprises the following steps:
[0052] S1. Preparation of aluminum phosphate xerogel: To 18 g of deionized water, 1.80 g of aluminum chloride and 1.54 g of phosphoric acid (85 wt %) were added in sequence. The mixture was stirred at 550 r / min at room temperature and then placed in an ice bath. When the water bath temperature reached 5°C, 8.0 mL of PO was added dropwise to obtain a hydrogel. The obtained hydrogel was dried at 110°C for 2 h, and then transferred to a culture dish and dried at 110°C for 4 h to obtain a highly uniform aluminum phosphate xerogel.
[0053] S2. Preparation of dry gel powder: The aluminum phosphate dry gel obtained in S1 and 0.46 g of ethyl orthosilicate were transferred to a mortar and ground and mixed thoroughly to obtain dry gel powder.
[0054] S3. Preparation of FAU-type aluminum phosphate molecular sieve: The dry gel powder obtained in S2 was transferred to an autoclave and immersed in 2.2 g of TPAOH solution (40 wt%) and 0.02 g of TMAOH solution (25 wt%) to form a homogeneous mixture. The molar ratio of SiO2, Al2O3, P2O5, TPAOH, TMAOH, and H2O in the resulting mixture was 0.4:1.0:1.5:1.6:0.2:40. The mixture was heated for crystallization at 200°C for 36 h. The crystallized solid product was thoroughly washed with water and centrifuged at 7000 rpm for 10 min. The separated precipitate was then dried in a 120°C oven for 4 h and then calcined at 500°C in air for 12 h to obtain the FAU-type aluminum silicophosphate molecular sieve.
[0055] Example 5
[0056] A zinc-doped FAU type aluminum phosphate-based molecular sieve, the preparation method of which comprises the following steps:
[0057] S1. Preparation of aluminum phosphate xerogel: To 18 g of deionized water, 2.40 g of aluminum chloride and 1.32 g of phosphoric acid (85 wt %) were added in sequence. The mixture was stirred at 550 r / min at room temperature and then placed in an ice bath. When the water bath temperature reached 5°C, 8.0 mL of PO was added dropwise to obtain a hydrogel. The obtained hydrogel was dried at 80°C for 2 h, and then transferred to a culture dish and dried at 120°C for 3 h to obtain a highly uniform aluminum phosphate xerogel.
[0058] S2. Preparation of dry gel powder: The aluminum phosphate dry gel obtained in S1 and 0.56 g of zinc nitrate were transferred to a mortar and ground and thoroughly mixed to obtain dry gel powder.
[0059] S3. Preparation of FAU-type aluminum phosphate molecular sieve: The dry gel powder obtained in S2 was transferred to an autoclave and immersed in 3.5 g of TPAOH solution (40 wt%) and 0.02 g of TMAOH solution (25 wt%) to form a homogeneous mixture. The molar ratio of Zn(NO3)2, Al2O3, P2O5, TPAOH, TMAOH, and H2O in the resulting mixture was 0.4:1.0:1.1:2.5:0.1:70. The mixture was heated for crystallization, i.e., reacted at 190°C for 24 h. The crystallized solid product was thoroughly washed with water and centrifuged at 8000 rpm for 10 min. The separated precipitate was then dried in an oven at 110°C for 3 h and then calcined at 450°C in air for 12 h to obtain the FAU-type zinc aluminum phosphate molecular sieve.
[0060] Example 6
[0061] A zinc-doped FAU type aluminum phosphate-based molecular sieve, the preparation method of which comprises the following steps:
[0062] S1. Preparation of aluminum phosphate xerogel: To 18 g of deionized water, 2.40 g of aluminum chloride and 1.45 g of phosphoric acid (85 wt %) were added in sequence. The mixture was stirred at 550 r / min at room temperature and then placed in an ice bath. When the water bath temperature reached 5°C, 8.0 mL of PO was added dropwise to obtain a hydrogel. The obtained hydrogel was dried at 100°C for 2 h, and then transferred to a culture dish and dried at 120°C for 2 h to obtain a highly uniform aluminum phosphate xerogel.
[0063] S2. Preparation of dry gel powder: The aluminum phosphate dry gel obtained in S1 and 0.82 g of zinc nitrate were transferred to a mortar and ground and mixed thoroughly to obtain dry gel powder.
[0064] S3, preparing the FAU-type aluminum phosphate-based molecular sieve: transferring the dry gel powder obtained in S2 into a high-pressure reaction kettle, immersing in 1.5 g of TPAOH solution (40 wt%) and 0.24 g of TMAOH solution (25 wt%) to form a uniform mixture, the molar ratio of Zn(NO3)2, Al2O3, P2O5, TPAOH, TMAOH and H2O in the obtained mixture being 0.5:1.0:1.3:2.5:0.2:30. Crystallizing the mixture by heating, i.e. reacting at 200°C for 36 h, and then washing the solid product obtained by crystallization with water, centrifuging at 8000 r / min for 10 min, drying the precipitate obtained by separation in an oven at 100°C for 6 h, and then calcining the precipitate in an air atmosphere at 550°C for 8 h to obtain the FAU-type zinc aluminum phosphate molecular sieve.
[0065] Example 7
[0066] A cobalt-doped FAU-type aluminum phosphate-based molecular sieve, a preparation method thereof comprising the following steps:
[0067] S1, preparing an aluminum phosphate dry gel: sequentially adding 2.40 g of aluminum chloride and 1.32 g of phosphoric acid (85 wt%) into 18 g of deionized water, stirring uniformly at a rotation speed of 550 r / min at room temperature, and then performing ice bath, when the water bath pot temperature shows 5°C, adding 8.0 mL of PO dropwise to obtain a hydrogel, drying the obtained hydrogel at 100°C for 2 h, and then transferring the hydrogel into a culture dish for drying at 110°C for 4 h to obtain a highly uniform aluminum phosphate dry gel.
[0068] S2, preparing a dry gel powder: transferring the aluminum phosphate dry gel obtained in S1 and 0.45 g of cobalt acetate into a mortar, and mixing uniformly by grinding to obtain a dry gel powder.
[0069] S3, preparing the FAU-type aluminum phosphate-based molecular sieve: transferring the dry gel powder obtained in S2 into a high-pressure reaction kettle, immersing in 1.6 g of TPAOH solution (40 wt%) and 0.24 g of TMAOH solution (25 wt%) to form a uniform mixture, the molar ratio of (CH3COO)2Co, Al2O3, P2O5, TPAOH, TMAOH and H2O in the obtained mixture being 0.4:1.0:1.1:2.4:0.15:26. Crystallizing the mixture by heating, i.e. reacting at 180°C for 24 h, and then washing the solid product obtained by crystallization with water, centrifuging at 8000 r / min for 15 min, drying the precipitate obtained by separation in an oven at 110°C for 4 h, and then calcining the precipitate in an air atmosphere at 500°C for 10 h to obtain the FAU-type cobalt aluminum phosphate molecular sieve.
[0070] Example 8
[0071] A cobalt-doped FAU-type aluminum phosphate-based molecular sieve, a preparation method thereof comprising the following steps:
[0072] S1, preparing aluminum phosphate xerogel: 2.40 g of aluminum chloride, 1.32 g of phosphoric acid (85 wt%) were sequentially added into 18 g of deionized water, and stirred at a speed of 550 r / min at room temperature until uniform, then ice bath was performed, when the water bath temperature showed 5°C, 8.0 mL of PO was added dropwise to obtain a hydrogel, the obtained hydrogel was dried at 80°C for 2 h, then transferred to a culture dish and dried at 120°C for 4 h to obtain a highly uniform aluminum phosphate xerogel.
[0073] S2, preparing dry gel powder: the aluminum phosphate xerogel obtained in S1 and 0.45 g of cobalt acetate were transferred to a mortar, and fully mixed by grinding to obtain a dry gel powder.
[0074] S3, preparing FAU-type aluminum phosphate-based molecular sieve: the dry gel powder obtained in S2 was transferred to a high-pressure reaction kettle, and immersed in 2.3 g of TPAOH solution (40 wt%) and 0.24 g of TMAOH solution (25 wt%) to form a uniform mixture, the molar ratio of (CH3COO)2Co, Al2O3, P2O5, TPAOH, TMAOH, H2O in the obtained mixture was 0.8:1.0:1.4:2.4:0.19:36. The mixture was heated and crystallized, i.e. reacted at 200°C for 20 h, the solid product obtained by crystallization was washed with water, centrifuged at 9000 r / min for 10 min, then the precipitate separated was dried in an oven at 100°C for 4 h, and then calcined at 550°C for 10 h in an air atmosphere to obtain a FAU-type cobalt aluminum phosphate molecular sieve.
[0075] Example 9
[0076] A gallium-doped FAU-type aluminum phosphate-based molecular sieve, the preparation method thereof comprises the following steps:
[0077] S1, preparing aluminum phosphate xerogel: 2.40 g of aluminum chloride, 1.32 g of phosphoric acid (85 wt%) were sequentially added into 18 g of deionized water, and stirred at a speed of 550 r / min at room temperature until uniform, then ice bath was performed, when the water bath temperature showed 5°C, 8.0 mL of PO was added dropwise to obtain a hydrogel, the obtained hydrogel was dried at 80°C for 2 h, then transferred to a culture dish and dried at 120°C for 4 h to obtain a highly uniform aluminum phosphate xerogel.
[0078] S2, preparing dry gel powder: the aluminum phosphate xerogel obtained in S1 and 0.45 g of cobalt acetate were transferred to a mortar, and fully mixed by grinding to obtain a dry gel powder.
[0079] S3, preparing the FAU-type aluminum phosphate-based molecular sieve: transferring the dry gel powder obtained in S2 into a high-pressure reaction kettle, immersing in 1.3 g of TPAOH solution (40 wt%) and 0.26 g of TMAOH solution (25 wt%) to form a uniform mixture, the molar ratio of Ga2O3, Al2O3, P2O5, TPAOH, TMAOH and H2O in the obtained mixture is 0.22:1.0:1.5:2.1:0.19:32. The mixture is subjected to heat crystallization, i.e. reacting at 200 ℃ for 24 h, and the solid product obtained by crystallization is washed with water, centrifuged at 9000 r / min for 10 min, and then the precipitate separated is dried in an oven at 100 ℃ for 4 h, and then calcined at 450 ℃ for 12 h in an air atmosphere to obtain the FAU-type gallium aluminum phosphate molecular sieve.
[0080] Example 10
[0081] A gallium-doped FAU-type aluminum phosphate-based molecular sieve, a preparation method thereof comprises the following steps:
[0082] S1, preparing an aluminum phosphate dry gel: sequentially adding 1.76 g of aluminum chloride and 1.73 g of phosphoric acid (85 wt%) into 18 g of deionized water, stirring uniformly at a rotation speed of 550 r / min at room temperature, and then performing ice bath, when the water bath pot temperature shows 5 ℃, adding 8.0 mL of PO dropwise to obtain a hydrogel, drying the obtained hydrogel at 100 ℃ for 2 h, and then transferring to a culture dish for drying at 120 ℃ for 4 h to obtain a highly uniform aluminum phosphate dry gel.
[0083] S2, preparing a dry gel powder: transferring the aluminum phosphate dry gel obtained in S1 and 0.42 g of gallium oxide into a mortar, and mixing uniformly by grinding to obtain a dry gel powder.
[0084] S3, preparing the FAU-type aluminum phosphate-based molecular sieve: transferring the dry gel powder obtained in S2 into a high-pressure reaction kettle, immersing in 1.3 g of TPAOH solution (40 wt%) and 0.26 g of TMAOH solution (25 wt%) to form a uniform mixture, the molar ratio of Ga2O3, Al2O3, P2O5, TPAOH, TMAOH and H2O in the obtained mixture is 0.22:1.0:1.5:2.1:0.19:32. The mixture is subjected to heat crystallization, i.e. reacting at 200 ℃ for 24 h, and the solid product obtained by crystallization is washed with water, centrifuged at 9000 r / min for 10 min, and then the precipitate separated is dried in an oven at 100 ℃ for 4 h, and then calcined at 450 ℃ for 12 h in an air atmosphere to obtain the FAU-type gallium aluminum phosphate molecular sieve.
[0085] Therefore, the present invention adopts the above-mentioned FAU type aluminum phosphate-based molecular sieve and its preparation method to prepare FAU structure molecular sieves doped with heteroatoms such as Si, Co, Zn, and Ga. The prepared aluminum phosphate-based molecular sieve has high crystallinity, adjustable acidity of the skeleton, and excellent hydrothermal stability.
[0086] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the same. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solutions of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.
Claims
1. A method for preparing a FAU type aluminum phosphate-based molecular sieve, characterized in that: The following steps are involved: S1. Preparation of aluminum phosphate xerogel: adding an aluminum source and phosphoric acid to deionized water in sequence, stirring at room temperature, and drying to obtain a highly uniform aluminum phosphate xerogel; S2. Preparing dry gel powder: Grind and thoroughly mix the aluminum phosphate dry gel obtained in S1 and the heteroatom to obtain dry gel powder; S3. Preparation of FAU type aluminum phosphate-based molecular sieve: The dry gel powder obtained in S2 is immersed in an organic amine solution to obtain a mixture, the mixture is heated and crystallized, and the solid product obtained by crystallization is washed with water, centrifuged, dried, and calcined to obtain a FAU type aluminum phosphate-based molecular sieve.
2. The preparation method according to claim 1, characterized in that In S1, the aluminum source is one of pseudo-boehmite, aluminum chloride, and aluminum isopropoxide; and the concentration of phosphoric acid is 20 wt % to 99 wt %.
3. The preparation method according to claim 1, characterized in that In S1, the molar ratio of Al2O3, P2O5, and H2O in the aluminum phosphate xerogel is 1:(0.1~5):(0.01~5).
4. The preparation method according to claim 1, characterized in that In S1, the stirring speed is 400-600 r / min, and the stirring time is 1-24 h; The drying temperature is 60-120℃ and the drying time is 2-12h.
5. The preparation method according to claim 1, characterized in that In S2, the heteroatom is one or more of a silicon source, a cobalt source, a zinc source, and a gallium source; The silicon source is one of white carbon black, ethyl orthosilicate, and silica sol; the cobalt source is one of cobalt acetate, cobalt sulfate, cobalt nitrate, and cobalt chloride; the zinc source is one of zinc acetate, zinc nitrate, zinc sulfate, and zinc chloride; and the gallium source is one of gallium oxide, gallium chloride, and gallium nitrate.
6. The preparation method according to claim 1, characterized in that In S3, the organic amine solution is one or more of tetrapropylammonium hydroxide solution and tetramethylammonium hydroxide solution.
7. The preparation method according to claim 6, characterized in that In S3, the concentration of tetrapropylammonium hydroxide in the tetrapropylammonium hydroxide solution is 5 wt% to 90 wt%; the concentration of tetramethylammonium hydroxide in the tetramethylammonium hydroxide solution is 5 wt% to 80 wt%.
8. The preparation method according to claim 7, characterized in that In S3, the molar ratio of Al2O3, P2O5, tetrapropylammonium hydroxide, tetramethylammonium hydroxide and H2O in the mixture is 1:(0.1~5):(0.1~10):(0.001~5):(0.01~40).
9. The preparation method according to claim 1, characterized in that In S3, the temperature for heating and crystallization is 120-250° C., and the time for heating and crystallization is 2-120 h; The drying temperature is 20-120℃ and the drying time is 1-24h; The calcination temperature is 300-600°C, and the calcination time is 2-12h.
10. A FAU type aluminum phosphate-based molecular sieve, characterized in that: The FAU-type aluminum phosphate-based molecular sieve is prepared by the preparation method according to any one of claims 1 to 9.