A silicoaluminophosphate molecular sieve and a method for its synthesis

Abstract

The application discloses a kind of phosphosilicate aluminum molecular sieve and synthesis method thereof, phosphosilicate aluminum molecular sieve belongs to inorganic solid porous crystalline material, with aluminophosphate-A type crystal structure;The framework structure of the phosphosilicate aluminum molecular sieve includes four kinds of elements of silicon, phosphorus, aluminum, oxygen.Phosphosilicate aluminum molecular sieve synthesis method is first mixed uniformly after phosphoric acid, silicon source, aluminum source, composite structure directing agent, water and obtains gel;Then the obtained gel is crystallized, and finally, after separation, drying and calcination, the phosphosilicate aluminum molecular sieve is obtained.The application provides a kind of method for synthesizing phosphosilicate aluminum molecular sieve using new composite structure directing agent, the synthesis method is simple and easy to operate, and the obtained phosphosilicate aluminum molecular sieve can be used as catalytic material or adsorption material.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of inorganic porous material synthesis, and particularly relates to a phosphosilicoaluminate material and a method for synthesizing the phosphosilicoaluminate material by using a composite structure directing agent. BACKGROUND

[0002] Since zeolite molecular sieves were first synthesized in the 1940s, inorganic porous crystalline materials represented by molecular sieves have attracted widespread attention. Such inorganic porous materials have a huge specific surface and a regular and adjustable pore structure, and have been widely used as important catalytic materials, adsorption and separation materials, and ion exchange materials in technical fields such as petroleum refining, petrochemicals, fine chemicals, etc. In addition, such materials also show good application prospects in the fields of light, electricity, magnetism, biology, medicine, sensing, and nanotechnology.

[0003] Phosphoaluminate molecular sieves are an important class of porous materials, which can be widely used in the fields of adsorption, separation, catalysis, and ion exchange. The United Carbon Corporation of the United States first developed a series of phosphoaluminate molecular sieves AlPO4-n (n represents the structure type), and then synthesized more than 60 different structure types of phosphoaluminate molecular sieves by changing the synthesis method and trying different template agents. Then, other types of elements were introduced into the framework of phosphoaluminate molecular sieves to partially replace P and Al in the framework, forming new types of heteroatom phosphoaluminate molecular sieves, expanding the structure types of molecular sieves, and expanding the applications of phosphoaluminate molecular sieves in catalysis, magnetism, electricity, optics, etc.

[0004] “P2O5-Al2O3-triethanolamine system hydrothermal crystallization of multi-directional” (Petroleum Science and Technology (Petroleum Chemicals), September 1989, Volume 5, Issue 3) discloses the synthesis of phosphoaluminate molecular sieves. By changing the preparation conditions of the P2O5-Al2O3-triethanolamine (TEA) system, 10 different structure types of crystalline products were obtained. Phosphoric acid, pseudo-boehmite, and triethanolamine were used as raw materials, and the synthesis was carried out under the conditions of P2O5 / Al2O3=1.0; TEA / Al2O3=0.1-1.0; H2O / Al2O3=40; colloid pH≥4.5; crystallization temperature 150℃. The crystal framework of the material is composed of aluminum, phosphorus, and oxygen, and the crystal structure is aluminophosphate-A.

[0005] CN111960429A discloses a preparation method of a multi-level pore phosphoaluminate molecular sieve catalyst, a catalyst prepared therefrom, and applications of the catalyst in olefin isomerization. The synthesis method grinds an aluminum source, a phosphorus source, a structure directing agent, a template agent, and an additive into a uniform mixture, adds water, and then uses megasonic waves for treatment. Then, a hydrothermal crystallization reaction is performed, followed by washing, drying, and calcination to obtain a phosphoaluminate molecular sieve catalyst with high crystallinity, regular morphology, high specific surface area, and composite multi-level pores.

[0006] CN112850734A discloses a cobalt-based multi-metallic single-atom isomorphous substituted phosphorus aluminum molecular sieve MeAPO-5 and a preparation method thereof, which takes an aluminum source, a phosphorus source, a template agent, a cobalt source, other doped metal sources and a mineralizer as basic synthesis raw materials, mixes all the raw materials uniformly through a specific feeding sequence, and adopts a two-stage short-time crystallization method to prepare the cobalt-based multi-metallic single-atom MeAPO-5 molecular sieve. SUMMARY

[0007] The main purpose of the present application is to provide a silicoaluminophosphate molecular sieve and a method for synthesizing the silicoaluminophosphate molecular sieve by using a novel composite structure directing agent.

[0008] The first aspect of the present application provides a silicoaluminophosphate molecular sieve, which belongs to inorganic solid porous crystalline materials and has an aluminophosphate-A type crystal structure. The framework structure of the silicoaluminophosphate molecular sieve includes four elements of silicon, phosphorus, aluminum and oxygen, and specifically includes a basic structural unit composed of a silicon-oxygen structure, an aluminum-oxygen structure and a phosphorus-oxygen structure and further forms a networked porous structure. The silicoaluminophosphate molecular sieve includes the XRD diffraction data listed in the following table:

[0009]

[0010] Further, the total specific surface area of the above-mentioned silicoaluminophosphate molecular sieve is 270-850 m 2 / g, preferably 300-800 m 2 / g.

[0011] Further, the crystal morphology of the above-mentioned silicoaluminophosphate molecular sieve is a block structure similar to a polyhedron, the overall external surface of the crystal is relatively flat, and part of the external surface has irregular step lines or protrusions. The microscale of the crystal changes with the change of the synthesis conditions, and in general cases, the average crystal size of the crystal is 0.3-10 microns.

[0012] The second aspect of the present application provides a synthesis method of a silicoaluminophosphate molecular sieve, which includes the following steps:

[0013] (1) mixing phosphoric acid, a silicon source, an aluminum source, a composite structure directing agent and water to obtain a gel after uniform mixing;

[0014] (2) performing a crystallization reaction on the gel obtained in step (1), and then obtaining the silicoaluminophosphate molecular sieve after separation, drying and calcination.

[0015] Further, in the synthesis method of the aluminophosphate-A molecular sieve, the aluminum source in step (1) is at least one of aluminum isopropoxide, aluminum butoxide, aluminum sec-butoxide, aluminum hydroxide, pseudo-boehmite, aluminum nitrate, aluminum sulfate, and aluminum chloride, and preferably at least one of aluminum isopropoxide, aluminum butoxide, and aluminum sec-butoxide. The aluminum source forms the framework of the aluminophosphate-A material in the hydrothermal crystallization reaction in the form of an aluminic microstructure.

[0016] Further, in the synthesis method of the aluminophosphate-A molecular sieve, the silicon source in step (1) is one or more of methyl orthosilicate, ethyl orthosilicate, white carbon black, silica gel, silica sol, and water glass, and preferably methyl orthosilicate and / or ethyl orthosilicate. The silicon source forms the framework of the aluminophosphate-A material in the hydrothermal crystallization reaction in the form of a siliconic microstructure.

[0017] Further, in the synthesis method of the aluminophosphate-A molecular sieve, the composite structure directing agent in step (1) is diethylamine and glutamine; the main function of the composite structure directing agent is to induce the raw materials to form the framework of the aluminophosphate-A material. In the hydrothermal synthesis process, the composite structure directing agent (diethylamine and glutamine) forms a complex structure with the silicon source, the aluminum source, and the phosphorus source, and finally forms the aluminophosphate-A framework. The applicant found in the research process that diethylamine and glutamine need to meet a certain ratio relationship to play a directing role. Single diethylamine or single glutamine cannot induce the formation of the aluminophosphate-A framework in the synthesis system of the present application.

[0018] Further, in the synthesis method of the aluminophosphate-A molecular sieve, the amount of each material in step (1) needs to meet a certain ratio relationship. Specifically, the molar ratio of phosphoric acid (calculated by P element), silicon source (calculated by SiO2), aluminum source (calculated by Al2O3), water, diethylamine, and glutamine is 2.5-8P:0.5-3.5SiO2:Al2O3:100-600H2O:3.5-8.5C4H 11 N:1.5-6.5 C5H 10 N2O3, and preferably 3-7P:1-3SiO2:Al2O3:150-500H2O:4-8 C4H 11 N:2-6 C5H 10 N2O3.

[0019] Further, in the synthesis method of the aluminophosphate-A molecular sieve, the crystallization reaction conditions in step (2) are as follows: the crystallization reaction temperature is 160-220°C, and preferably the crystallization reaction temperature is 170-210°C; the crystallization reaction time is 25-130h, and preferably the crystallization reaction time is 30-120h.

[0020] Further, in the synthesis method of the silicoaluminophosphate molecular sieve, the separation in step (2) can be performed by filtration, which usually includes multiple filtrations, typically 1-10 times.

[0021] Further, in the synthesis method of the silicoaluminophosphate molecular sieve, the drying temperature in step (2) is 100-150°C, and the drying time is 1-10 h.

[0022] Further, in the synthesis method of the silicoaluminophosphate molecular sieve, the calcination in step (2) is high-temperature calcination at 400-600°C for 1-10 h, which is usually performed in an air or oxygen atmosphere.

[0023] The third aspect of the present application provides a silicoaluminophosphate molecular sieve, which is synthesized by the above method.

[0024] The silicoaluminophosphate molecular sieve provided by the present application or the silicoaluminophosphate molecular sieve material synthesized by the above method is a solid crystal material, which belongs to aluminophosphate-A type in crystallographic classification, has a porous structure, a pore size range of less than 2 nm, and belongs to microporous structure material according to the pore size classification, can perform screening on molecules of nanoscale size, and has good molecular transmission capacity, a total specific surface area range of 270-850 m 2 / g, belongs to a relatively high specific surface area porous material, and can provide sufficient reaction sites for catalytic reactions or sufficient adsorption sites for gaseous or liquid substances.

[0025] The main framework structure elements of the silicoaluminophosphate molecular sieve provided by the present application include silicon, phosphorus, aluminum, and oxygen, and specifically, the basic structure unit is composed of silicon-oxygen structure, aluminum-oxygen structure, and phosphorus-oxygen structure, and finally forms a network structure porous structure. Since the silicon, phosphorus, and aluminum exposed on the outer surface of the material have unsaturation on the valence bond, the material can form an action force with hydrocarbon molecules and has a certain catalytic performance, and can also form a strong interaction with metal elements to adsorb metal elements and be used as a carrier of metal catalysts.

[0026] The silicoaluminophosphate molecular sieve provided by the present application can also be used after further modification treatment, and the modification treatment can adopt any one of the existing modification methods for molecular sieve materials in the field. Specifically, the silicoaluminophosphate molecular sieve can be used for separating and purifying one or several components from gaseous or liquid raw materials. The silicoaluminophosphate molecular sieve can also be used as a carrier of a hydrogenation catalyst.

[0027] The present application provides a novel silicoaluminophosphate molecular sieve and a synthesis method thereof, and the silicoaluminophosphate molecular sieve is synthesized by using a novel composite directing agent, the method is simple and easy to operate, and the operation is simple. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 XRD pattern of the molecular sieve obtained in Example 1.

[0029] Figure 2 Transmission electron micrograph of the molecular sieve obtained in Example 1. DETAILED DESCRIPTION

[0030] The technical solutions and implementation technical effects of the present application are further illustrated below in combination with examples, comparative examples and the drawings, but are not limited to the following examples.

[0031] The endpoints of the ranges and any values disclosed herein are not limited to the precise values stated. The endpoints of the ranges and any values are understood to be approximate values. The endpoints of the ranges and individual values are understood to be approximate values for the range. The approximate values allow for variation based on experimental error, measurement techniques, variability, and the like. Any numerical value can be converted to a range by adding or subtracting a value from the numerical value. Any range can be subdivided into a number of smaller ranges having endpoints that are the approximate values.

[0032] In the present application, unless otherwise explicitly stated, the percentages, percentage contents are by mass.

[0033] In the present application, the phase structure of the silicoaluminophosphate molecular sieve is characterized by X-ray diffraction, using a D / max2500 X-ray diffractometer from Rigaku, Japan, Cu target, Kα radiation source, graphite monochromator, tube voltage 40 kV, tube current 80 mA, scanning range 5°-40°, step size 0.1°, scanning speed 1 ° / min.

[0034] In the present application, the pore structure of the silicoaluminophosphate molecular sieve is measured by N2 adsorption-desorption, using an ASAP2420 physical adsorption instrument from Micromeritics, USA. Before measurement, the sample is treated in vacuum at 300°C for 4 h or more. The total specific surface area and other parameters are calculated according to the BET isotherm equation.

[0035] In the present application, the microstructure of the silicoaluminophosphate molecular sieve is characterized by high-resolution electron microscopy, using a JEM-2100 LaB6 high-resolution transmission electron microscope from JEOL, Japan, for sample morphology observation and electron diffraction analysis, and using a Gatan 832 CCD camera from Gatan, USA, to collect images and electron diffraction spectra.

[0036] Example 1

[0037] A clean container was taken and 11.5 g of phosphoric acid, 18 g of diethylamine, 18 g of glutamine, 10 g of aluminum isopropoxide were dissolved in 100 g of distilled water, 7 g of tetraethyl orthosilicate was added and mixed well. The mixture was then treated at 200 °C for 100 h. The resulting sample was filtered several times and then dried in an oven at 110 °C for 12 h. Finally, the sample was calcined in air at 550 °C for 5 h. The sample obtained was numbered as A1.

[0038] Example 2

[0039] A clean container was taken and 7.2 g of phosphoric acid, 7.16 g of diethylamine, 7.2 g of glutamine, 10 g of aluminum isopropoxide were dissolved in 67 g of distilled water, 5.1 g of tetraethyl orthosilicate was added and mixed well. The mixture was then treated at 170 °C for 30 h. The resulting sample was filtered several times and then dried in an oven at 110 °C for 12 h. Finally, the sample was calcined in air at 550 °C for 5 h. The sample obtained was numbered as A2.

[0040] Example 3

[0041] A clean container was taken and 16.1 g of phosphoric acid, 30.2 g of diethylamine, 45.8 g of glutamine, 10 g of aluminum isopropoxide were dissolved in 220 g of distilled water, 15.0 g of tetraethyl orthosilicate was added and mixed well. The mixture was then treated at 210 °C for 120 h. The resulting sample was filtered several times and then dried in an oven at 110 °C for 12 h. Finally, the sample was calcined in air at 550 °C for 5 h. The sample obtained was numbered as A3.

[0042] Example 4

[0043] A clean container was taken and 8.5 g of phosphoric acid, 17 g of diethylamine, 25.8 g of glutamine, 12 g of aluminum isopropoxide were dissolved in 200 g of distilled water, 7.5 g of tetraethyl orthosilicate was added and mixed well. The mixture was then treated at 190 °C for 80 h. The resulting sample was filtered several times and then dried in an oven at 110 °C for 12 h. Finally, the sample was calcined in air at 550 °C for 5 h. The sample obtained was numbered as A4.

[0044] Example 5

[0045] A clean container was taken and 12.5 g of phosphoric acid, 15.5 g of diethylamine, 20 g of glutamine, 11 g of aluminum isopropoxide were dissolved in 155 g of distilled water, 9 g of tetraethyl orthosilicate was added and mixed well. The mixture was then treated at 185 °C for 90 h. The resulting sample was filtered several times and then dried in an oven at 110 °C for 12 h. Finally, the sample was calcined in air at 550 °C for 5 h. The sample obtained was numbered as A5.

[0046] Comparative Example 1

[0047] A clean container was taken and 11.5 g of phosphoric acid, 18 g of glutamine, 10 g of aluminum sec-butoxide were dissolved in 100 g of distilled water, 7 g of tetraethyl orthosilicate was added, mixed uniformly, then treated at 200°C for 100 h; the obtained sample was filtered several times, then placed in an oven at 110°C for 12 h, and finally calcined at 550°C in air for 5 h, the obtained sample was numbered as A6, and the obtained product was amorphous, and no silico-aluminum phosphate molecular sieve was synthesized.

[0048] Comparative Example 2

[0049] A clean container was taken and 11.5 g of phosphoric acid, 18 g of glutamine, 10 g of aluminum sec-butoxide were dissolved in 100 g of distilled water, 7 g of tetraethyl orthosilicate was added, mixed uniformly, then treated at 200°C for 100 h; the obtained sample was filtered several times, then placed in an oven at 110°C for 12 h, and finally calcined at 550°C in air for 5 h, the obtained sample was numbered as A6, and the obtained product was amorphous, and no silico-aluminum phosphate molecular sieve was synthesized.

[0050] Comparative Example 3

[0051] A clean container was taken and 11.5 g of phosphoric acid, 18 g of glutamine, 10 g of aluminum sec-butoxide were dissolved in 100 g of distilled water, 7 g of tetraethyl orthosilicate was added, mixed uniformly, then treated at 200°C for 100 h; the obtained sample was filtered several times, then placed in an oven at 110°C for 12 h, and finally calcined at 550°C in air for 5 h, the obtained sample was numbered as A6, and the obtained product was amorphous, and no silico-aluminum phosphate molecular sieve was synthesized.

[0052] Comparative Example 4

[0053] Compared with Example 4, the ratio of diethylamine and glutamine is higher than the upper limit of the ratio in the specification.

[0054] A clean container was taken and 11.5 g of phosphoric acid, 18 g of glutamine, 10 g of aluminum sec-butoxide were dissolved in 100 g of distilled water, 7 g of tetraethyl orthosilicate was added, mixed uniformly, then treated at 200°C for 100 h; the obtained sample was filtered several times, then placed in an oven at 110°C for 12 h, and finally calcined at 550°C in air for 5 h, the obtained sample was numbered as A6, and the obtained product was amorphous, and no silico-aluminum phosphate molecular sieve was synthesized.

[0055] Table 1 Physical and chemical properties of the samples of the examples and comparative examples

[0056]

[0057] Note: In the present application, the crystallinity of the sample in Example 1 is defined as 100%, specifically, the height of the peak with the strongest diffraction intensity in the XRD spectrum of the sample in Example 1 is defined as 100%. The crystallinity of all other samples is obtained by comparing the height of the peak with the strongest diffraction intensity in the XRD spectrum of the sample to be compared with the sample in Example 1, i.e. the reference sample.

Claims

1. A silicoaluminophosphate molecular sieve, which belongs to inorganic solid porous crystalline material, has aluminophosphate-A type crystal structure; the framework structure of the silicoaluminophosphate molecular sieve comprises four elements of silicon, phosphorus, aluminum and oxygen, and is composed of basic structural units of silicon-oxygen structure, aluminum-oxygen structure and phosphorus-oxygen structure and further forms a network porous structure; the silicoaluminophosphate molecular sieve comprises XRD diffraction data listed in the following table: 。 2. The silicoaluminophosphate molecular sieve of claim 1, characterized by: The total specific surface area of the phosphosilicate aluminums molecular sieve is 270-850 m 2 / g.

3. The silicoaluminophosphate molecular sieve of claim 1, wherein: The total specific surface area of the phosphosilicate aluminums molecular sieve is 300-800 m 2 / g.

4. The silicoaluminophosphate molecular sieve of Claim 1, characterized by: The crystal morphology of the silicoaluminophosphate molecular sieve is a block structure similar to a polyhedron, the overall external surface of the crystal is relatively flat, part of the external surface has irregular step lines or protrusions, and the average crystal size of the crystal is 0.3-10 microns.

5. A synthesis method of a silicoaluminophosphate molecular sieve, comprising the following steps: (1) mixing phosphoric acid, a silicon source, an aluminum source, a composite structure directing agent, and water, and obtaining a gel after uniform mixing, wherein the composite structure directing agent is diethylamine and glutamine; (2) performing a crystallization reaction on the gel obtained in step (1), and then obtaining the silicoaluminophosphate molecular sieve after separation, drying and calcination.

6. The method of synthesizing a silicoaluminophosphate molecular sieve according to Claim 5, characterized by: The aluminum source in step (1) is at least one of isopropyl aluminum, butyl aluminum, sec-butyl alcohol aluminum, aluminum hydroxide, pseudo-boehmite, aluminum nitrate, aluminum sulfate and aluminum chloride.

7. The method of synthesizing a silicoaluminophosphate molecular sieve according to Claim 5, characterized by: The aluminum source in step (1) is at least one of isopropyl aluminum, butyl aluminum and sec-butyl alcohol aluminum.

8. The method of synthesizing a silicoaluminophosphate molecular sieve according to Claim 5, characterized by: The silicon source in step (1) is one or more of methyl orthosilicate, ethyl orthosilicate, white carbon black, silica gel, silica sol and water glass.

9. The method of synthesizing a silicoaluminophosphate molecular sieve according to Claim 5, characterized by: The silicon source in step (1) is methyl orthosilicate and / or ethyl orthosilicate.

10. The method of synthesizing a silicoaluminophosphate molecular sieve according to Claim 5, characterized by: The various materials in step (1) need to satisfy the following ratio relationship, the molar ratio of phosphoric acid calculated by P element, silicon source calculated by SiO2, aluminum source calculated by Al2O3, water, diethylamine, glutamine is 2.5-8P:0.5-3.5SiO2:Al2O3:100-600H2O:3.5-8.5C4H 11 N:1.5-6.5 C5H 10 N2O3.

11. The method of synthesizing a silicoaluminophosphate molecular sieve according to Claim 5, characterized by: The various materials in step (1) need to meet the following ratio relationship, the molar ratio of phosphoric acid calculated as P element, silicon source calculated as SiO2, aluminum source calculated as Al2O3, water, diethylamine, glutamine is 3-7P: 1-3SiO2: Al2O3: 150-500H2O: 4-8 C4H 11 N: 2-6 C5H 10 N2O3.

12. The method of synthesizing a silicoaluminophosphate molecular sieve according to Claim 5, characterized by: The crystallization reaction conditions in step (2) are as follows: the crystallization reaction temperature is 160-220°C, and the crystallization reaction time is 25-130h.

13. The method of synthesizing a silicoaluminophosphate molecular sieve according to Claim 5, characterized by: The crystallization reaction conditions in step (2) are as follows: the crystallization reaction temperature is 170-210°C, and the crystallization reaction time is 30-120h.

14. The method of synthesizing a silicoaluminophosphate molecular sieve according to Claim 5, characterized by: The drying temperature in step (2) is 100-150°C, and the drying time is 1-10h.

15. The method of synthesizing a silicoaluminophosphate molecular sieve according to Claim 5, characterized by: The calcination in step (2) is calcination treatment at 400-600°C for 1-10h, and the calcination is performed in an air or oxygen atmosphere.

16. A silicoaluminophosphate molecular sieve, which is synthesized by the method according to any one of claims 5-15.

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