CN118877908A

CN118877908A - Aluminum phosphate LTA molecular sieve and preparation method and application thereof

Info

Publication number: CN118877908A
Application number: CN202410931699.7A
Authority: CN
Inventors: 厉晓蕾; 宋欣宁; 陶硕
Original assignee: Liaocheng University
Current assignee: Liaocheng University
Priority date: 2024-07-11
Filing date: 2024-07-11
Publication date: 2024-11-01

Abstract

The invention discloses an aluminum phosphate LTA molecular sieve and a preparation method and application thereof, which belong to the technical field of molecular sieve porous materials, and particularly relate to a preparation method of the aluminum phosphate LTA molecular sieve, and the preparation method comprises the following steps: mixing deionized water, an aluminum source, a phosphoric acid solution and an HF solution, and stirring for the first time to obtain a premix; adding propylene oxide into the premix under the ice bath stirring condition to obtain hydrogel; drying and grinding to obtain aluminum phosphate xerogel powder; mixing with water, dropwise adding a template agent, stirring for the second time, and performing first drying treatment to obtain an aluminum phosphate precursor; crystallizing, ultrasonic treating, washing, baking, and baking to obtain the final product. The invention adopts a single small molecular reagent as a template agent, and the prepared molecular sieve has small particle size, large specific surface area and regular pore canal structure, has good hydrothermal stability and has wide prospect in the aspect of adsorption separation of multi-component gas.

Description

Aluminum phosphate LTA molecular sieve and preparation method and application thereof

Technical Field

The invention belongs to the technical field of molecular sieve porous materials, and particularly relates to an aluminum phosphate LTA molecular sieve, and a preparation method and application thereof.

Background

The small molecule separation technology mainly separates and purifies a large amount of chemical mixtures generated in the industrial fields of chemical industry, petrochemical industry, pharmacy and the like, and the main means at present comprise: cryogenic distillation, membrane separation, adsorptive separation, and the like. The adsorption separation technology is a technology for realizing the separation of multicomponent mixed gas by utilizing the strong adsorption capacity of a porous solid adsorbent to selectively adsorb substances on the surface of the solid. The conventional adsorption separation process is to pass the gas mixture through an adsorption column filled with adsorbent, and the weakly adsorbed gas component flows out preferentially to obtain a product, and the strongly adsorbed gas component needs to be desorbed so as to realize the regeneration and the reuse of the adsorbent. Common porous materials for adsorptive separation include: activated carbon, molecular sieve, porous alumina, metal organic framework material, etc., wherein the molecular sieve has the characteristics of wide sources, low cost, simple synthesis, uniform micropore structure, high specific surface area, good hydrothermal stability, etc., and is widely applied in the field of adsorption separation.

The molecular sieve is a porous solid material with ordered pore canal with molecular size, which is mainly divided into silicate and aluminosilicate, the ordered pore canal structure ensures that the molecular sieve has excellent performance in adsorption separation, and meanwhile, the acidity of the molecular sieve can be changed by adjusting the silicon-aluminum ratio; the specific surface area is high, and the pore size distribution is uniform; the synthesis steps are simple, and the template agent is low in cost and easy to obtain; good hydrothermal stability and chemical stability, and the like, which makes the adsorbent material stand out from a plurality of adsorbent materials. The aluminum phosphate molecular sieve with LTA (International molecular sieve Association designation code) topological structure belongs to a cubic crystal system, has 8-ring aperture and larger alpha cage, is a three-dimensional pore structure, and has the aperture of 0.41nm. Because of its unique pore size structure, it can be used as a good adsorbent material.

Conventionally, LTA molecular sieves are prepared using various structure directing methods under hydrothermal conditions, and it is currently known that LTA molecular sieves are prepared using various structure directing agents under hydrothermal conditions in cooperation, for example, a mixture of tetramethylammonium hydroxide (TMAOH-5H ₂ O, 97%), hydrofluoric acid (48%), tetraethyl silicate (TEOS, 98%), aluminum hydroxide (Al (OH) ₃), is mixed in the presence of an imidazole-based (e.g., 1, 2-dimethylimidazole, 1, 2-dimethyl-3- (3-methylbenzyl) imidazole, etc.) organic structure directing agent, and then the resulting mixture is heated at 80 ℃, followed by loading the mixed product into a reaction vessel, heating at 175 ℃ for a desired time under dynamic conditions at 60rpm, washing the product with deionized water, drying overnight at room temperature, and calcining in air at 600 ℃ for 8 hours to obtain LTA molecular sieves. Compared with the method, the method has the advantages of large material consumption, high cost, low environmental friendliness, large molecular sieve particle size and small specific surface area, and is unfavorable for mass transfer and gas adsorption.

Currently, most LTA molecular sieves are oriented by a traditional hydrothermal method using synergistic action of two or more templates, for example: kryptofix 222, a ternary organic template agent and the like, the prior method has the defects of large material consumption, high cost and serious environmental pollution, and the prepared molecular sieve has larger particle size and low specific surface area, and is not beneficial to adsorbing small molecular substances.

Disclosure of Invention

In order to solve the technical problems, the invention provides the aluminum phosphate LTA molecular sieve, the preparation method and the application thereof, and the single small molecular reagent is used as a template agent, so that the prepared molecular sieve has small particle size, large specific surface area and regular pore channel structure, has good hydrothermal stability and has wide prospect in the aspect of adsorption and separation of multicomponent gas.

In order to achieve the above purpose, the invention provides a preparation method of an aluminum phosphate LTA molecular sieve, which comprises the following steps:

(1) Mixing deionized water, an aluminum source, a phosphoric acid solution and an HF solution, and stirring for the first time to obtain a premix;

(2) Adding propylene oxide into the premix in the step (1) under the ice bath stirring condition to obtain hydrogel;

(3) The hydrogel obtained in the step (2) is dried and ground to obtain aluminum phosphate xerogel powder;

(4) Mixing the aluminum phosphate xerogel powder in the step (3) with water, dropwise adding a template agent, stirring for the second time, and performing first drying treatment to obtain an aluminum phosphate precursor;

(5) And (3) crystallizing, ultrasonically washing 3 times, performing second drying treatment and roasting the aluminum phosphate precursor in the step (4) to obtain the aluminum phosphate LTA molecular sieve.

Preferably, the aluminum source in the step (1) is one of crystalline aluminum chloride, pseudo-boehmite and aluminum isopropoxide; in the step (1), water is used as a solvent for the phosphoric acid solution, and the concentration of the phosphoric acid solution is 70-99 wt%; the HF solution in the step (1) takes water as a solvent, and the concentration of the HF solution is 30-70wt%.

Preferably, the premix in step (1) further comprises one of heteroatoms Fe, co, mg, ni, si or Cu and an ethanol solution; the ethanol solution takes water as a solvent, and the concentration of the ethanol solution is 75-99 wt%.

Preferably, in the step (1), the temperature of the first stirring is 15-30 ℃, the time of the first stirring is 0.5-4 h, and the rotating speed of the first stirring is 50-100 r/min; the temperature of the ice bath stirring in the step (2) is-5 ℃, the time of the ice bath stirring is 0.1-2 h, and the rotating speed of the ice bath stirring is 50-100 r/min.

Preferably, the molar ratio of Al ₂O₃：P₂O₅：HF：PO：H₂ O in the hydrogel in the step (2) is 0.1-1.0: 0.1 to 5.0:0.1 to 2.0:1.0 to 50:20.0 to 1000 or M: the mole ratio of Al ₂O₃：P₂O₅：HF：PO：H₂ O is 0.001-2.0: 1.0:0.2 to 5.0:0.001 to 2.0:1.0 to 50:20 to 1000, wherein M represents one of a heteroatom Fe, co, mg, ni, si or Cu.

Preferably, the temperature of the drying in the step (3) is 80-120 ℃, and the drying time is 1-24 hours.

Preferably, the template agent in the step (4) is one of tetramethyl ammonium hydroxide, di-n-propylamine, 1-ethyl-3-methylimidazole bromide or 1-butyl-3-methylimidazole bromide; the dropping speed of the template agent in the step (4) is 1-50 drops/min; the second stirring time in the step (4) is 2-6 h, and the rotating speed of the second stirring is 50-100 r/min; the temperature of the first drying treatment in the step (4) is 60-100 ℃, and the time of the first drying treatment is 0.5-10 h.

Preferably, the crystallization temperature in the step (5) is 150-200 ℃, and the crystallization time is 1-72 h; the power of the ultrasonic wave in the step (5) is 50-300W, and the time of the ultrasonic wave is 5-30 min; the temperature of the second drying in the step (5) is 80-120 ℃, the time of the second drying is 1-12 h, the temperature of the roasting in the step (5) is 450-600 ℃, and the time of the roasting is 4-16 h.

The invention also provides the aluminum phosphate LTA molecular sieve prepared by the preparation method.

The invention also provides application of the aluminum phosphate LTA molecular sieve or the aluminum phosphate LTA molecular sieve prepared by the preparation method in adsorption separation of multicomponent gas.

Compared with the prior art, the invention has the following advantages and technical effects:

1) The invention provides a method for synthesizing an aluminum phosphate LTA molecular sieve by using a sol-gel method, wherein in the prior art, most of the molecular sieve can only be synthesized by adopting the synergistic effect of two or more than two templates, the particle size of the obtained aluminum phosphate LTA molecular sieve is larger, the adsorption separation of gas is not facilitated, the synthesized LTA molecular sieve breaks the defect of large particle size in the past, the synthesized molecular sieve has small particle size, unique 8-membered ring pore diameter, large specific surface area and good hydrothermal stability, and even under the condition of higher temperature and lower pressure, the adsorption capacity is higher, and the adsorption separation of multicomponent gas has the appearance of bright eyes;

2) The aluminum phosphate LTA molecular sieve prepared by the invention introduces hetero atoms into the LTA molecular sieve framework, endows the molecular sieve with new active sites, improves the acidity and redox of the molecular sieve, and has wide prospect in the adsorption separation of multicomponent gas.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are needed in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

FIG. 1 is an XRD spectrum of an aluminum phosphate LTA molecular sieve prepared in example 1 of the present invention;

FIG. 2 is an SEM image of an aluminum phosphate LTA molecular sieve prepared in example 1 of the present invention, scale 2 μm;

FIG. 3 is a single component adsorption isotherm of N ₂、CO₂、CH₄ at 298K for the aluminum phosphate LTA molecular sieve prepared in example 1 of the present invention;

FIG. 4 is a plot of the ideal adsorption selectivity of the aluminum phosphate LTA molecular sieve prepared in example 1 of the present invention to CO ₂/N₂;

FIG. 5 is a plot of the ideal adsorption selectivity of the aluminum phosphate LTA molecular sieve prepared in example 1 of the present invention to CO ₂/CH₄;

FIG. 6 is a plot of the ideal adsorption selectivity of the aluminum phosphate LTA molecular sieve prepared in example 1 of the present invention to CH ₄/N₂.

Detailed Description

Various exemplary embodiments of the invention will now be described in detail, which should not be considered as limiting the invention, but rather as more detailed descriptions of certain aspects, features and embodiments of the invention.

It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. In addition, for numerical ranges in this disclosure, it is understood that each intermediate value between the upper and lower limits of the ranges is also specifically disclosed. Every smaller range between any stated value or stated range, and any other stated value or intermediate value within the stated range, is also encompassed within the invention. The upper and lower limits of these smaller ranges may independently be included or excluded in the range.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention. All documents mentioned in this specification are incorporated by reference for the purpose of disclosing and describing the methods and/or materials associated with the documents. In case of conflict with any incorporated document, the present specification will control.

It will be apparent to those skilled in the art that various modifications and variations can be made in the specific embodiments of the invention described herein without departing from the scope or spirit of the invention. Other embodiments will be apparent to those skilled in the art from consideration of the specification of the present invention. The specification and examples of the present invention are exemplary only.

As used herein, the terms "comprising," "including," "having," "containing," and the like are intended to be inclusive and mean an inclusion, but not limited to.

Example 1

(1) Adding 9g of deionized water and 0.701g of pseudo-boehmite into a 50mL beaker in sequence, mixing, slowly dripping 1.2g H ₃PO₄ g of solution (85 wt%) and 0.2g of HF solution (40 wt%) according to 10 drops/min in sequence, and stirring for 2h at the temperature of 23 ℃ at the rotation speed of 500r/min to obtain a premix;

(2) Under the ice bath condition of 0 ℃, 6mL of propylene oxide is slowly added dropwise into the premix at 12 drops/min, and the mixture is stirred for 1h in the ice bath at the temperature of 0 ℃ at the rotating speed of 200r/min until the solution becomes a gel state, so as to obtain hydrogel, wherein Al ₂O₃：P₂O₅ in the hydrogel: HF: PO (propylene oxide): the molar ratio of H ₂ O is 1.0:1.0:0.8:14.3:100;

(3) Drying the hydrogel (putting into an oven at 80 ℃ for ageing for 2 hours, transferring into a culture dish after ageing is finished, drying for 2 hours in an oven at 100 ℃), and grinding to obtain aluminum phosphate xerogel powder;

(4) Taking one of 50mL beakers, adding aluminum phosphate xerogel powder and 18g of deionized water, mixing, slowly dripping 2.8g of di-n-propylamine (DPA) according to 10 drops/min, stirring for 4h at a rotating speed of 500r/min, and performing first drying treatment in a 100 ℃ oven for 2h to obtain an aluminum phosphate precursor;

(5) The aluminum phosphate precursor is put into a reaction kettle for crystallization for 24 hours at 180 ℃, the ultrasonic power is 100W, the ultrasonic power is 15 minutes, the aluminum phosphate precursor is washed for 3 times, the aluminum phosphate precursor is subjected to second drying treatment at 100 ℃ for 6 hours, and the aluminum phosphate LTA molecular sieve is obtained after roasting for 8 hours at 500 ℃ in air atmosphere.

The selectivity of the aluminum phosphate LTA molecular sieves prepared in example 1 for separation of multicomponent gases at 298K was further evaluated using Ideal Adsorption Solution Theory (IAST). A binary Langmuir-Freundlich equation was used to fit the single component adsorption isotherms.

As shown in fig. 1 to 6, as can be seen from the XRD spectrum of fig. 1, the aluminum phosphate LTA molecular sieve prepared in example 1 has strong diffraction peaks at 2θ=7.41 °, 10.49 °, 12.85 °, 22.38 °, 24.78 °, and compared with standard cards, the aluminum phosphate LTA molecular sieve prepared in example 1 has a typical LTA topology structure, and meanwhile, the XRD spectrum baseline of the aluminum phosphate LTA molecular sieve prepared in example 1 is stable, the intensity of the diffraction peak is high and no distinct impurity peak is found, which indicates that the aluminum phosphate LTA molecular sieve has high crystallinity and purity.

As shown in FIG. 2, in an SEM image of the aluminum phosphate LTA molecular sieve prepared in example 1, LTA crystals have a typical cubic structure, and most of the LTA crystals have a particle size of 0.5-1 μm. The single component adsorption isotherms of the prepared aluminum phosphate LTA molecular sieve of example 1 on CO ₂、CH₄ and N ₂ under 298K conditions are shown in fig. 3, and the adsorption capacity of the prepared aluminum phosphate LTA molecular sieve on CO ₂ is far higher than that of CH ₄ and N ₂, on the one hand, because the molecular size of CO ₂ is smaller than that of CH ₄ and N ₂(CO₂:0.33nm,CH₄:0.38nm,N₂: 0.36nm, and on the other hand, because the strong quadrupole moment of CO ₂ has enough interaction capacity, the molecular sieve pore cations can be induced to deviate temporarily and reversibly from the pore centers, so that the CO ₂ molecules pass through the molecular sieve.

The selectivity of the molecular sieve for separating the multicomponent gases was then further evaluated for the aluminum phosphate LTA prepared at 298K using Ideal Adsorption Solution Theory (IAST). A binary Langmuir-Freundlich equation was used to fit the single component adsorption isotherms. As shown in fig. 4 to 6, it can be seen that the ideal selectivity of the aluminum phosphate LTA molecular sieve sample prepared in example 1 to CO ₂/N₂、CO₂/CH₄、CH₄/N₂ is lower (less than 20 Kpa), the selectivity is gradually decreased, the selectivity is gradually increased with increasing pressure, and finally, the ideal selectivity reaches 36.5, 16.2 and 4.2 respectively at 100Kpa, which are all higher than the literature values, which indicates that the aluminum phosphate LTA molecular sieve sample prepared in example 1 has good multi-component gas separation performance.

Example 2

(1) 9G of deionized water and 1.402g of pseudo-boehmite are sequentially added into a 50mL beaker to be mixed, 1.5g H ₃PO₄ g of solution (85 wt%) and 0.3g of HF solution (40 wt%) are sequentially and slowly added dropwise according to 5 drops/min, and the mixture is stirred for 2 hours at the temperature of 25 ℃ for the first time at 600r/min to obtain a premix;

(2) Slowly dropwise adding 4.0mL of propylene oxide into the premix at 12 drops/min under the ice bath condition of 0 ℃, stirring for 1h at the ice bath condition of 0 ℃ at 400r/min until the solution becomes a gel state, and obtaining the hydrogel, wherein Al ₂O₃：P₂O₅ in the hydrogel: HF: PO (propylene oxide): the molar ratio of H ₂ O is 1.0:1.25:1.2:11.4:100;

(4) Taking one of 50mL beakers, adding aluminum phosphate xerogel powder and 18g of deionized water, mixing, slowly dripping 2.8g of di-n-propylamine (DPA) at 10 drops/min, stirring for 4h at 400r/min, and performing first drying treatment in a 100 ℃ oven for 5h to obtain an aluminum phosphate precursor;

(5) The aluminum phosphate precursor is put into a reaction kettle, crystallized for 24 hours at 180 ℃, washed 3 times by ultrasonic power of 200W for 10 minutes, subjected to second drying treatment at 100 ℃ for 6 hours, and baked for 8 hours at 500 ℃ in air atmosphere, thus obtaining the aluminum phosphate LTA molecular sieve.

Example 3

(1) 18G of deionized water and 0.701g of pseudo-boehmite are sequentially added into a 50mL beaker to be mixed, 1.2g H ₃PO₄ g of solution (85 wt%) and 0.2g of HF solution (40 wt%) are sequentially and slowly added dropwise according to 15 drops/min, and the mixture is stirred for 2 hours at 25 ℃ at a rotating speed of 300r/min to obtain a premix;

(2) Under the ice bath condition of 0 ℃, 6mL of propylene oxide is slowly added dropwise into the premix at 12 drops/min, 300r/min is stirred for 1h in the ice bath of 0 ℃ until the solution becomes a gel state, and the hydrogel is obtained, wherein Al ₂O₃：P₂O₅ in the hydrogel: HF: PO (propylene oxide): the molar ratio of H ₂ O is 1.0:1.0:0.8:16:200;

(4) Taking one of 50mL beakers, adding aluminum phosphate xerogel powder, mixing with 18g of deionized water, slowly dripping 3g of di-n-propylamine (DPA) at 12 drops/min, stirring for 4h at 400r/min, and performing first drying treatment in a 100 ℃ oven for 4h to obtain an aluminum phosphate precursor;

(5) The aluminum phosphate precursor is put into a reaction kettle, crystallized for 12 hours at 200 ℃, washed 3 times by ultrasonic power of 50W for 20 minutes, subjected to second drying treatment at 100 ℃ for 6 hours, and baked for 8 hours at 500 ℃ in air atmosphere, thus obtaining the aluminum phosphate LTA molecular sieve.

Example 4

(1) 18G of deionized water and 1.402g of pseudo-boehmite are sequentially added into a 50mL beaker to be mixed, 1.2g H ₃PO₄ g of solution (85 wt%) and 0.3g of HF solution (40 wt%) are sequentially and slowly added dropwise according to 10 drops/min, and the mixture is stirred for 2 hours at the speed of 500r/min at the temperature of 30 ℃ to obtain a premix;

(2) Slowly dropwise adding 4.5mL of propylene oxide into the premix at 12 drops/min under the ice bath condition of 0 ℃, stirring for 1h at the ice bath condition of 0 ℃ at the rotating speed of 400r/min until the solution becomes a gel state, and obtaining the hydrogel, wherein the Al ₂O₃：P₂O₅ in the hydrogel: HF: PO (propylene oxide): the molar ratio of H ₂ O is 1.0:0.5:0.6:6.4:100;

(4) Taking one of 50mL beakers, adding aluminum phosphate xerogel powder, mixing with 18g of deionized water, slowly dripping 1.8g of di-n-propylamine (DPA) at 8 drops/min, stirring for 4h at a rotating speed of 500r/min, and performing first drying treatment in a 100 ℃ oven for 4h to obtain an aluminum phosphate precursor;

(5) The aluminum phosphate precursor is put into a reaction kettle for crystallization for 8 hours at 160 ℃, the ultrasonic power is 100W, the ultrasonic power is 5 minutes, the aluminum phosphate precursor is washed for 3 times, the aluminum phosphate precursor is subjected to second drying treatment for 6 hours at 100 ℃, and the aluminum phosphate LTA molecular sieve is obtained after roasting for 8 hours at 500 ℃ in air atmosphere.

Example 5

(1) 18G of deionized water, 0.701g of pseudo-boehmite and 0.354g of cobalt acetate are sequentially added into a 50mL beaker to be mixed, 1.2g H ₃PO₄ g of solution (85 wt%) and 0.2g of HF solution (40 wt%) are slowly added dropwise according to 15 drops/min in sequence, and the mixture is stirred for 2 hours at 30 ℃ at a rotating speed of 300r/min to obtain a premix;

(2) Under the ice bath condition of 0 ℃, 6mL of propylene oxide is slowly added dropwise into the premix at 12 drops/min, and the mixture is stirred for 1h in the ice bath at the temperature of 0 ℃ at the rotating speed of 450r/min until the solution becomes a gel state, so as to obtain hydrogel, wherein Co ₂O₃：Al₂O₃：P₂O₅ in the hydrogel: HF: PO (propylene oxide): the molar ratio of H ₂ O is 0.20:1.0:1.0:0.8:17.2:200;

(3) Drying the hydrogel (putting into an oven at 80 ℃ for ageing for 2 hours, transferring into a culture dish after ageing is finished, drying for 2 hours in an oven at 100 ℃), and grinding to obtain cobalt aluminum phosphate xerogel powder;

(4) Taking another 50mL beaker, adding cobalt aluminum phosphate xerogel powder and 18g deionized water, mixing, slowly dripping 2.0g di-n-propylamine (DPA) at 20 drops/min, stirring for 4h at a rotation speed of 500r/min, and performing first drying treatment in a 100 ℃ oven for 4h to obtain a cobalt aluminum phosphate precursor;

(5) Putting the cobalt aluminum phosphate precursor into a reaction kettle, crystallizing for 12 hours at 170 ℃, performing water washing for 3 times by using ultrasonic power of 100W for 20 minutes, performing second drying treatment for 6 hours at 100 ℃, and roasting for 12 hours at 500 ℃ in air atmosphere to obtain the cobalt aluminum phosphate LTA molecular sieve.

Example 6

(1) 9G of deionized water, 0.701g of pseudo-boehmite and 0.527g of cobalt acetate are sequentially added into a 50mL beaker to be mixed, 2.4g H ₃PO₄ g of solution (85 wt%) and 0.2g of HF solution (40 wt%) are slowly added dropwise according to 10 drops/min in sequence, and the mixture is stirred for 2 hours at 30 ℃ at a rotating speed of 500r/min to obtain a premix;

(2) Under the ice bath condition of 0 ℃, slowly dropwise adding 6mL of propylene oxide into the premix at 20 drops/min, stirring for 1h in the ice bath at the temperature of 0 ℃ at the rotating speed of 300r/min until the solution becomes a gel state, and obtaining the hydrogel, wherein Co ₂O₃：Al₂O₃：P₂O₅ in the hydrogel: HF: PO (propylene oxide): the molar ratio of H ₂ O is 0.30:1.0:2.0:0.8:17.2:100;

(3) Drying the hydrogel (putting into an oven at 80 ℃ for ageing for 2 hours, transferring into a culture dish after ageing is finished, drying for 2 hours in an oven at 120 ℃), and grinding to obtain cobalt aluminum phosphate xerogel powder;

(4) Taking another 50mL beaker, adding cobalt aluminum phosphate xerogel powder and 10g deionized water, mixing, slowly dripping 3.5g di-n-propylamine (DPA) at 20 drops/min, stirring for 4h at 400r/min, and performing first drying treatment in a 100 ℃ oven for 6h to obtain a cobalt aluminum phosphate precursor;

(5) Putting the cobalt aluminum phosphate precursor into a reaction kettle, crystallizing for 24 hours at 150 ℃, carrying out water washing for 3 times by using ultrasonic power of 150W for 10 minutes, carrying out second drying treatment at 120 ℃ for 6 hours, and roasting for 8 hours at 550 ℃ in air atmosphere to obtain the cobalt aluminum phosphate LTA molecular sieve.

Example 7

(1) 9G of deionized water, 10g of absolute ethyl alcohol, 0.701g of pseudo-boehmite and 0.416g of tetraethoxysilane are sequentially added into a 50mL beaker to be mixed, 1.2g H ₃PO₄ g of solution (85 wt%) and 0.3g of HF solution (40 wt%) are slowly added dropwise according to 10 drops/min in sequence, and the mixture is stirred for 2 hours at 30 ℃ at a rotating speed of 300r/min to obtain a premix;

(2) Slowly dropwise adding 4mL of propylene oxide into the premix at 15 drops/min under the ice bath condition at the temperature of 0 ℃, stirring for 1h in an ice bath at the temperature of 0 ℃ at the rotating speed of 300r/min until the solution becomes a gel state, and obtaining SiO ₂：Al₂O₃：P₂O₅ in the hydrogel: HF: PO (propylene oxide): the molar ratio of H ₂ O is 0.20:1.0:1.0:1.2:11.5:100;

(3) Drying the hydrogel (putting into an oven at 80 ℃ for ageing for 2 hours, transferring into a culture dish after ageing is finished, drying for 4 hours in an oven at 100 ℃), and grinding to obtain silicon aluminum phosphate xerogel powder;

(4) Taking one of 50mL beakers, adding silicon aluminum phosphate xerogel powder, mixing with 18g of deionized water, slowly dripping 2.5g of di-n-propylamine (DPA) at 20 drops/min, stirring for 4h at a rotating speed of 200r/min, and performing first drying treatment in a 100 ℃ oven for 6h to obtain a silicon aluminum phosphate precursor;

(5) The silicon aluminum phosphate precursor is put into a reaction kettle for crystallization for 18 hours at 180 ℃, the ultrasonic power is 150W, the ultrasonic power is 25 minutes, the silicon aluminum phosphate precursor is washed for 3 times, the silicon aluminum phosphate precursor is subjected to second drying treatment at 100 ℃ for 6 hours, and the silicon aluminum phosphate LTA molecular sieve is obtained after roasting for 10 hours at 550 ℃ in air atmosphere.

Example 8

(1) 9G of deionized water, 10g of absolute ethyl alcohol, 0.701g of pseudo-boehmite and 0.284g of magnesium acetate tetrahydrate are sequentially added into a 50mL beaker to be mixed, 1.2g H ₃PO₄ g of solution (85 wt%) and 0.25g of HF solution (40 wt%) are slowly added dropwise according to 15 drops/min in sequence, and the mixture is stirred for 2 hours at 30 ℃ at a rotating speed of 500r/min to obtain a premix;

(2) Slowly dropwise adding 5mL of propylene oxide into the premix at 10 drops/min under the ice bath condition of 0 ℃, stirring for 1h at the ice bath condition of 0 ℃ at the rotating speed of 300r/min until the solution becomes a gel state, and obtaining hydrogel, wherein MgO in the hydrogel: al ₂O₃：P₂O₅: HF: PO (propylene oxide): the molar ratio of H ₂ O is 0.10:1.0:1.0:1.0:14.3:100;

(3) Drying the hydrogel (putting into an oven at 80 ℃ for ageing for 2 hours, transferring into a culture dish after ageing is finished, drying for 2 hours in an oven at 120 ℃), and grinding to obtain magnesium aluminum phosphate xerogel powder;

(4) Taking one of 50mL beakers, adding magnesium aluminum phosphate xerogel powder and 18g of deionized water, mixing, slowly dripping 1.6g of di-n-propylamine (DPA) at 15 drops/min, stirring for 4h at a rotating speed of 450r/min, and performing first drying treatment in a 100 ℃ oven for 6h to obtain a magnesium aluminum phosphate precursor;

(5) And (3) putting the magnesium aluminum phosphate precursor into a reaction kettle, crystallizing for 6 hours at 190 ℃, washing for 3 times by using ultrasonic power of 300W for 5 minutes, performing second drying treatment at 100 ℃ for 6 hours, and roasting for 8 hours at 500 ℃ in air atmosphere to obtain the magnesium aluminum phosphate LTA molecular sieve.

The above embodiments are only illustrative of the preferred embodiments of the present invention and are not intended to limit the scope of the present invention, and various modifications and improvements made by those skilled in the art to the technical solutions of the present invention should fall within the protection scope defined by the claims of the present invention without departing from the design spirit of the present invention.

Claims

1. The preparation method of the aluminum phosphate LTA molecular sieve is characterized by comprising the following steps of:

2. The method of claim 1, wherein the aluminum source in step (1) is one of crystalline aluminum chloride, pseudo-boehmite, and aluminum isopropoxide; in the step (1), water is used as a solvent for the phosphoric acid solution, and the concentration of the phosphoric acid solution is 70-99 wt%; the HF solution in the step (1) takes water as a solvent, and the concentration of the HF solution is 30-70wt%.

3. The method of claim 1, wherein the premix in step (1) further comprises one of heteroatoms Fe, co, mg, ni, si or Cu and an ethanol solution; the ethanol solution takes water as a solvent, and the concentration of the ethanol solution is 75-99 wt%.

4. The preparation method according to claim 1, wherein the temperature of the first stirring in the step (1) is 15-30 ℃, the time of the first stirring is 0.5-4 h, and the rotating speed of the first stirring is 50-100 r/min; the temperature of the ice bath stirring in the step (2) is-5 ℃, the time of the ice bath stirring is 0.1-2 h, and the rotating speed of the ice bath stirring is 50-100 r/min.

5. The method according to claim 1 or 3, wherein the molar ratio of Al ₂O₃：P₂O₅：HF：PO：H₂ O in the hydrogel in step (2) is 0.1 to 1.0:0.1 to 5.0:0.1 to 2.0:1.0 to 50:20.0 to 1000 or M: the mole ratio of Al ₂O₃：P₂O₅：HF：PO：H₂ O is 0.001-2.0: 1.0:0.2 to 5.0:0.001 to 2.0:1.0 to 50:20 to 1000, wherein M represents one of a heteroatom Fe, co, mg, ni, si or Cu.

6. The method according to claim 1, wherein the drying temperature in the step (3) is 80 to 120 ℃ and the drying time is 1 to 24 hours.

7. The method according to claim 1, wherein the template agent in the step (4) is one of tetramethylammonium hydroxide, di-n-propylamine, 1-ethyl-3-methylimidazolium bromide or 1-butyl-3-methylimidazolium bromide; the dropping speed of the template agent in the step (4) is 1-50 drops/min; the second stirring time in the step (4) is 2-6 h, and the rotating speed of the second stirring is 50-100 r/min; the temperature of the first drying treatment in the step (4) is 60-100 ℃, and the time of the first drying treatment is 0.5-10 h.

8. The method according to claim 1, wherein the crystallization temperature in the step (5) is 150 to 200 ℃, and the crystallization time is 1 to 72 hours; the power of the ultrasonic wave in the step (5) is 50-300W, and the time of the ultrasonic wave is 5-30 min; the temperature of the second drying in the step (5) is 80-120 ℃, the time of the second drying is 1-12 h, the temperature of the roasting in the step (5) is 450-600 ℃, and the time of the roasting is 4-16 h.

9. The aluminum phosphate LTA molecular sieve prepared by the preparation method of any one of claims 1 to 8.

10. Use of an aluminium phosphate LTA molecular sieve according to claim 9 or prepared by a method according to any one of claims 1 to 8 in the adsorptive separation of a multi-component gas.