A molecular sieve and its preparation method and application in water adsorbent

Abstract

This application relates to a molecular sieve DNL-12, its preparation method and application in water adsorbent, belonging to the field of molecular sieves. The chemical formula of the molecular sieve is (H2O) x R2((Si y Al 8‑y P8O 32 ), wherein x = 0 to 5.5, y = 0 to 2.2; the molecular sieve has a three-dimensional cross-channel structure of 10×8×8-membered rings; the synthesis process is simple and operability is strong. It can be used for adsorption separation and has high water adsorption capacity.

Description

Technical Field

[0001] The present application relates to a molecular sieve, a preparation method thereof and an application in a water adsorbent. The applicant names it DNL-12, which belongs to the field of molecular sieves. Background Art

[0002] Since 1982, Wilson of Union Carbide Corporation (UCC) of the United States has successfully developed a series of PO2 + and AlO2 - Aluminophosphate molecular sieves (AlPO), composed of tetrahedral interconnected vertices with regular pores or cage-like structures, have significantly expanded the molecular sieve family. The P and Al in AlPO molecular sieves can be easily isomorphously replaced by other metallic elements such as Si or Mg, forming silicoaluminophosphate molecular sieves (SAPO) and metalloaluminophosphate molecular sieves (MeAPO). The AlPO molecular sieve framework is electrically neutral, resulting in unique adsorption properties, which have been applied in the fields of adsorption separation and adsorption energy storage.

[0003] Phosphoalumino molecular sieves are typically synthesized hydrothermally, and organic templates appear to be essential. Through the design, synthesis, and introduction of various organic templates, the phosphoalumino molecular sieve family has grown to 46 members. However, compared to silica-alumino molecular sieves, there is still significant room for development. The lack of material types is also significantly hindering understanding of the microscopic environment during adsorption or catalysis.

[0004] Based on pore size, molecular sieve materials can be classified as small-pore, medium-pore, large-pore, and ultra-large-pore molecular sieves, corresponding to windows with rings of less than 8, less than 10, less than 12, and greater than 12 members, respectively. Based on pore dimension, molecular sieve materials can be categorized as one-dimensional, two-dimensional, and three-dimensional. Different pore dimensions and sizes also determine the material's application in adsorption separation.

[0005] Three-dimensional aluminophosphate molecular sieves have a wide range of applications, but until now, three-dimensional mesoporous aluminophosphate molecular sieves have been lacking. Developing different pore types, expanding the AlPO molecular sieve family, and exploring the microscopic processes involved in their synthesis are challenges facing researchers. Summary of the Invention

[0006] According to the first aspect of the present application, a novel three-dimensional mesoporous molecular sieve DNL-12 is provided. This molecular sieve is a mesoporous molecular sieve material of aluminum phosphate or aluminum silicophosphate, and has very important theoretical significance for enriching the aluminum phosphate molecular sieve structure family.

[0007] The molecular sieve has a three-dimensional cross-channel structure of 10×8×8 rings;

[0008] The X-ray powder diffraction of the molecular sieve has diffraction peaks at least at the following positions.

[0009]

[0010] The chemical formula of the molecular sieve is (H2O) x R2((Si y Al 8-y P8O 32 ),

[0011] Where x = 0 to 5.5, y = 0 to 2.2;

[0012] R has the structure shown in Formula I:

[0013]

[0014] Wherein, R1, R2, R3, R4, R5, R6, R7, and R8 are independently selected from a hydrogen atom or a methyl group.

[0015] According to another aspect of the present application, a method for synthesizing the above-mentioned molecular sieve is provided, comprising at least the following steps:

[0016] (1) mixing water, a phosphorus source, an aluminum source, a silicon source, an organic template, a mineralizer, and a solvent to obtain a mixture;

[0017] (2) crystallizing the mixture obtained in (1) in a closed reactor to obtain a crystallized product;

[0018] (3) calcining the crystallized product to remove the template to obtain the molecular sieve.

[0019] Optionally, the method comprises the following steps:

[0020] (1) Under stirring conditions, a phosphorus source, an aluminum source, a silicon source, an organic template, water, a fluoride, and an alcohol (triethylene glycol (TEG)) are uniformly mixed in proportion to form a reaction gel;

[0021] (2) transferring the reaction gel into a stainless steel reactor and crystallizing it at 80-240° C. for 1-60 days under sealed conditions;

[0022] (3) washing and drying the crystallized product to obtain DNL-12;

[0023] The organic template has a structure shown in Formula II:

[0024]

[0025] Wherein, R1, R2, R3, R4, R5, R6, R7, and R8 are independently selected from a hydrogen atom or a methyl group.

[0026] Optionally, the organic template is selected from 2,2-bipyridine and / or 4,4-dimethyl-2,2-bipyridine.

[0027] The phosphorus source is selected from phosphoric acid and / or phosphorus pentoxide;

[0028] The aluminum source is selected from at least one of pseudo-boehmite, aluminum hydroxide or aluminum isopropoxide;

[0029] The silicon source is selected from at least one of silica sol, ethyl orthosilicate, tetramethoxysilane or white carbon black;

[0030] The mineralizer is selected from HF and / or NH4F; the fluoride ions therein are effective.

[0031] The solvent is selected from alcohols.

[0032] Optionally, the solvent is selected from glycols.

[0033] Optionally, the alcohol is selected from triethylene glycol.

[0034] The molar composition of the mixture is aR:bHF:cH3PO4:qSiO2:Al2O3:mTEG:nH2O;

[0035] in,

[0036] a=0.1~5.0;

[0037] b = 0 to 3.6;

[0038] c=1.0~6.0;

[0039] q = 0 to 1.0;

[0040] m=0~50;

[0041] n=5~1000.

[0042] Optionally, a is independently selected from any value among 0.10, 0.2, 0.5, 1.0, 1.2, 1.6, 1.9, 2.0, 2.4, 2.5, 2.8, 3.1, 3.3, 3.8, 3.9, 4.0, 4.2, 4.3, 4.6, 4.8, 5.0 or any range therebetween.

[0043] Optionally, b is independently selected from any value among 0, 0.2, 0.5, 0.8, 1.0, 1.2, 1.5, 1.8, 2.0, 2.1, 2.3, 2.4, 2.8, 3.0, 3.1, 3.2, 3.4, 3.6 or any range therebetween.

[0044] Optionally, c is independently selected from any value among 1.0, 1.2, 1.5, 1.7, 1.8, 2.0, 2.5, 2.8, 3.0, 3.6, 4.0, 4.2, 4.6, 5.0, 5.3, 5.5, 5.6, 5.8, 6.0 or any range therebetween.

[0045] Optionally, c is independently selected from any value among 1.7, 1.8, 2.0, 2.5, or any range therebetween.

[0046] Optionally, q is independently selected from any value among 0, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0 or any range therebetween.

[0047] Optionally, q is independently selected from any value among 0, 0.1, 0.15, 0.2, or any range therebetween.

[0048] Optionally, m is independently selected from any value among 0, 10, 15, 20, 30, 40, 50 or any range therebetween.

[0049] Optionally, m is independently selected from any value among 20, 30, 40, or any range between the two.

[0050] Optionally, n is independently selected from any value among 10, 20, 25, 30, 50, 80, 100, 150, 200, 400, 600, 800, 1000, 2000 or any range therebetween.

[0051] The crystallization temperature is 80 to 240° C.

[0052] Optionally, the crystallization temperature is independently selected from any value among 80℃, 90℃, 110℃, 130℃, 150℃, 160℃, 170℃, 180℃, 190℃, 200℃, 210℃, 220℃, 230℃, 240℃ or any range between two values.

[0053] The crystallization time is 1 to 60 days.

[0054] Optionally, the crystallization time is independently selected from 1 day, 2 days, 3 days, 4 days, 5 days, 6 days, 7 days, 8 days, 9 days, 10 days, 12 days, 13 days, 14 days, 15 days, 18 days, 20 days, 23 days, 25 days, 28 days, 30 days, 33 days, 35 days, 38 days, 40 days, 43 days, 45 days, 48 ​​days, 50 days, 53 days, 55 days, 58 days, 60 days, or any range between two of them.

[0055] Optionally, the crystallization temperature is 130-200°C;

[0056] Optionally, the crystallization temperature is independently selected from any value among 130°C, 150°C, 160°C, 170°C, 180°C, 190°C, 200°C, or any range therebetween.

[0057] The crystallization time is 1 to 15 days.

[0058] Optionally, the crystallization time is independently selected from any value among 1 day, 2 days, 3 days, 4 days, 5 days, 6 days, 7 days, 8 days, 9 days, 10 days, 12 days, 13 days, 14 days, 15 days, or any range therebetween.

[0059] According to another aspect of the present application, there is provided an application of the above-mentioned molecular sieve as a water adsorption material.

[0060] According to another aspect of the present application, a water adsorbent is provided, wherein the water adsorbent contains the above-mentioned molecular sieve or the molecular sieve prepared by the above-mentioned preparation method.

[0061] The water adsorbent is used for absorbing water and storing energy.

[0062] The water absorption capacity of the water adsorbent can reach more than 100 mg / g.

[0063] The beneficial effects of this application include:

[0064] 1) This application synthesized a new type of framework structure molecular sieve.

[0065] 2) The preparation method provided in this application has a simple synthesis process and strong operability.

[0066] 3) The novel framework structure molecular sieve prepared in this application can be used for adsorption separation and has high water adsorption capacity. BRIEF DESCRIPTION OF THE DRAWINGS

[0067] Figure 1 This is the X-ray powder diffraction pattern (XRD) of the product obtained in Example 1 of the present application.

[0068] Figure 2 This is a scanning electron microscope (SEM) image of the product obtained in Example 1 of the present application.

[0069] Figure 3 This is the water absorption isotherm curve of DNL-12 in Example 13 of the present application. DETAILED DESCRIPTION

[0070] The present application is described in detail below with reference to embodiments, but the present application is not limited to these embodiments.

[0071] Unless otherwise specified, the raw materials in the examples of this application were purchased through commercial channels.

[0072] The analysis method in the examples of this application is as follows:

[0073] The sample phase analysis was carried out by X-ray powder diffraction (XRD) analysis. The instrument used was an X'Pert PRO X-ray diffractometer from PANalytical, the Netherlands, using a Cu target and a Kα light source. Tested under 40KV voltage and 40mA current conditions.

[0074] The composition of the samples was determined by X-ray fluorescence spectroscopy (XRF) using a Philips Magix-601 X-ray fluorescence spectrometer.

[0075] The sample morphology was analyzed by scanning electron microscopy (SEM), and the instrument used was a Hitachi SU8020 field emission scanning electron microscope.

[0076] The samples were thermally analyzed using a TAQ-600 thermal analyzer at a heating rate of 10°C / min from room temperature to 900°C.

[0077] The water vapor adsorption test of the samples was carried out using a BSD-VVS multi-station gravimetric gas vapor adsorption instrument produced by Bester Company at a P / P0 of 0.8 and a temperature of 25°C.

[0078] cRED data were collected on a JEOL 2100Plus transmission electron microscope equipped with an EMSIS GmbH camera and an ASI Cheetah120 detector.

[0079] Example 1 Preparation of Sample 1

[0080] 5.69g of orthophosphoric acid (85%) was added to 5.4g of deionized water and stirred. 3.69g of pseudoboehmite (67.5%) was then added and stirred until homogeneous. 1.31g of 2,2-bipyridine (98%) was then added and mixed vigorously (500 rpm) to obtain an initial gel mixture. The mixture was transferred to a stainless steel autoclave and statically crystallized at 200°C under autogenous pressure for 72 hours. After crystallization, the solid product was centrifuged, washed, and air-dried at 100°C to obtain a white powder product.

[0081] The product was confirmed to be DNL-12 by X-ray powder diffraction and was recorded as sample 1. The X-ray powder diffraction pattern (XRD) of sample 1 is shown in FIG. Figure 1 As shown in the scanning electron microscope (SEM) Figure 2As shown, the particles of sample 1 are square and the size ranges from 200nm to 1μm. At the same time, the morphology of the molecular sieve in the SEM image is uniform, and the synthesized molecular sieve does not contain other phases, indicating that the molecular sieve is highly pure. The elemental composition of sample 1 obtained by XRF analysis and thermal analysis normalization is: (H2O)2R2·(P8Al8 O 32 ), wherein R is 2,2-bipyridine.

[0082] The X-ray powder diffraction characteristics of sample 1 are shown in Table 1:

[0083]

[0084]

[0085] Example 2 Preparation of Sample 2

[0086] 0.95g of aluminum triisopropoxide was added to 10.39g of triethylene glycol and stirred. 0.54g of orthophosphoric acid (85%) was then added to the mixture and stirred thoroughly. 1.09g of 2,2-bipyridine was added and mixed thoroughly. Finally, 0.34g of hydrofluoric acid was added. The colloid was transferred to a 100ml Teflon-lined stainless steel kettle and statically crystallized at 200°C for 72 hours. The solid product was centrifuged, washed, and air-dried at 100°C to obtain a white powder product. X-ray powder diffraction confirmed the product to be DNL-12, designated Sample 2. The scanning electron micrograph (SEM) of Sample 2 was similar to that of Sample 1.

[0087] Example 3 Preparation of Sample 3

[0088] 0.95g of aluminum triisopropoxide was added to 10.39g of triethylene glycol and stirred. 0.54g of orthophosphoric acid (85%) was then added to the mixture and stirred thoroughly. 1.09g of 2,2-bipyridine was added and mixed thoroughly. Finally, 0.34g of hydrofluoric acid was added. The colloid was transferred to a 100ml Teflon-lined stainless steel kettle and statically crystallized at 200°C for 72 hours. The solid product was centrifuged, washed, and air-dried at 100°C to obtain a white powder product. X-ray powder diffraction confirmed the product to be DNL-12 and designated Sample 3. The scanning electron micrograph (SEM) of Sample 2 was similar to that of Sample 1.

[0089] Example 4 Preparation of Sample 4

[0090] 0.07g of aluminum triisopropoxide was added to 16.40g of triethylene glycol and stirred. 0.12g of orthophosphoric acid (85%) was then added to the mixture and stirred thoroughly. 0.07g of 2,2-bipyridine was added and mixed thoroughly. The colloid was statically crystallized at 200°C for 72 hours. The solid product was centrifuged, washed, and air-dried at 100°C to obtain a white powder product. X-ray powder diffraction confirmed the product to be DNL-12, designated Sample 4.

[0091] Example 5 Preparation of Samples 5 to 11

[0092] The preparation process of Examples 5 to 11 is the same as that of Examples 1 to 4. The specific proportions of ingredients are shown in Table 1.

[0093] Table 1 Preparation of samples 5 to 11 of Examples 5 to 11

[0094]

[0095]

[0096] Example 12 Structural Analysis

[0097] Continuous rotating electron diffraction (cRED) tests were performed on samples 1-3. The structural analysis results showed that DNL-12 crystallized in the monoclinic system with a P21 / m space group. The unit cell parameters obtained by structural refinement were β = 110.452. The information of the molecular sieve framework and the template can be obtained.

[0098] Example 13 DNL-12 is used for water absorption reaction

[0099] This example is used to illustrate the use of DNL-12 as a water adsorbent. However, the molecular sieve of this application is not limited to use for water adsorption.

[0100] The samples obtained in Examples 1 to 11 were directly loaded into the adsorption instrument for pretreatment. The pretreatment conditions were heating at 250°C to constant weight; then a constant temperature water bath was used to stabilize the temperature at 25°C and the water vapor adsorption test was started. Typical experimental results are shown in Figure 3 . Figure 3 The experimental results show that when P / P0 is 0.8, the water vapor adsorption capacity is 100.493 mg / g. Other samples have achieved similar results.

[0101] The above descriptions are merely a few embodiments of the present application and do not constitute any form of limitation to the present application. Although the present application discloses the preferred embodiments as above, they are not intended to limit the present application. Any technical personnel familiar with the present profession, without departing from the scope of the technical solution of the present application, using the technical content disclosed above to make slight changes or modifications are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A molecular sieve, characterized in that The molecular sieve has a three-dimensional cross-channel structure of 10×8×8 rings; The X-ray powder diffraction of the molecular sieve has diffraction peaks at least at the following positions: 。 2. The molecular sieve according to claim 1, characterized in that The chemical formula of the molecular sieve is (H2O) x R2((Si y Al 8-y P8O 32 ), Where x = 0 to 5.5, y = 0 to 2.2; R has the structure shown in Formula I: Wherein, R1, R2, R3, R4, R5, R6, R7, and R8 are independently selected from a hydrogen atom or a methyl group.

3. A method for synthesizing the molecular sieve according to any one of claims 1 or 2, characterized in that: At least the following steps are included: (1) mixing water, a phosphorus source, an aluminum source, a silicon source, an organic template, a mineralizer, and a solvent to obtain a mixture; (2) crystallizing the mixture obtained in (1) in a closed reactor to obtain a crystallized product; (3) calcining the crystallized product to remove the template to obtain the molecular sieve.

4. The preparation method according to claim 3, characterized in that The organic template is selected from 2,2-bipyridine and / or 4,4-dimethyl-2,2-bipyridine.

5. The preparation method according to claim 3, characterized in that The phosphorus source is selected from phosphoric acid and / or phosphorus pentoxide; The aluminum source is selected from at least one of pseudo-boehmite, aluminum hydroxide or aluminum isopropoxide; The silicon source is selected from at least one of silica sol, ethyl orthosilicate, tetramethoxysilane or white carbon black; The mineralizer is selected from HF and / or NH4F; The solvent is selected from glycols.

6. The preparation method according to claim 3, characterized in that The molar composition of the mixture is aR:bHF:cH3PO4:qSiO2:Al2O3:mTEG:nH2O; in, a＝0.1～5.0； b＝0～3.6； c＝1.0～6.0； q＝0～1.0； m＝0～50； n＝5～1000。 7. The preparation method according to claim 3, characterized in that The crystallization temperature is 80 to 240° C. The crystallization time is 1 to 60 days.

8. The preparation method according to claim 3, characterized in that The crystallization temperature is 130-200°C; The crystallization time is 1 to 15 days.

9. Use of the molecular sieve according to any one of claims 1 or 2, characterized in that: As water adsorbent.

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