Molecular sieve DNL-14, its preparation method and application

Abstract

The application discloses a molecular sieve DNL-14 and a preparation method thereof, and belongs to the technical field of molecular sieves. x P 48‑x Al 48 O 192 ).8R.yH2Ox for each mole of Si x P 48‑x Al 48 O 192 Mol of Si, x = 0-2.0, y is the Mol of H2O in each mole of Si x P 48‑x Al 48 O 192 Y = 0-10.0; R is an organic template 1,8-bisdimethylaminonaphthalene; the molecular sieve has a three-dimensional 8*8*20-membered ring pore structure, is tetragonal, and belongs to I4 space group; the particle of the molecular sieve is rod-shaped, and the length is 1-2 mm. The application synthesizes a novel framework structure silicoaluminophosphate molecular sieve, which can be used for adsorption separation and has high water adsorption; the synthesis process is simple and has high operability.

Description

Technical Field

[0001] This invention belongs to the field of molecular sieve technology, and particularly relates to a molecular sieve DNL-14, its preparation method and application. Background Technology

[0002] Molecular sieves are porous materials with regular channels or cage-like structures. They can be classified according to their elemental composition, such as silicon-aluminum molecular sieves, phosphorus-aluminum molecular sieves, and silicon-germanium molecular sieves. Their complex and diverse channel structures allow molecular sieves to play an important role in adsorption separation, industrial catalysis, and other fields.

[0003] Based on pore size, molecular sieve materials can be classified into micropore, mesopore, macropore, and ultramacropore molecular sieves, corresponding to windows with fewer than 8-membered rings, fewer than 10-membered rings, fewer than 12-membered rings, and larger than 12-membered rings, respectively. Based on pore dimension, molecular sieve materials can be classified into one-dimensional, two-dimensional, and three-dimensional materials. Different pore dimensions and sizes also determine the application of this material in adsorption and separation.

[0004] Currently, ultra-large pore molecular sieves are still relatively rare in the phosphorus-aluminum molecular sieve system. In recent years, researchers have made significant breakthroughs in the field of phosphorus-aluminum molecular sieves, particularly in terms of the pore structure of new materials. Examples include the earliest VFI molecular sieve (18 rings), followed by IFO (16 rings) molecular sieves, and then DNL-1 (20 rings) molecular sieves. DNL-1 is currently the phosphorus-aluminum molecular sieve with the largest number of rings in its pore structure. Summary of the Invention

[0005] In view of this, the present invention provides a molecular sieve DNL-14, its preparation method and application. The main purpose is to develop a molecular sieve with a three-dimensional 8*8*20-membered ring channel structure. This molecular sieve is a mesoporous molecular sieve material of aluminum phosphate or aluminum silicophosphate, which enriches the structural types of aluminum phosphate molecular sieves.

[0006] On one hand, the present invention provides a molecular sieve DNL-14, the chemical composition of which is as follows:

[0007] (Si x P 48-x Al 48 O 192 Formula I: 8R.yH2O

[0008] In Equation I, x represents the number of moles of Si. x P 48-x Al 48 O 192 The number of moles of Si in the sample, x = 0 to 2.0.

[0009] y represents the number of moles of Si x P 48-x Al 48 O192 The number of moles of H2O in the solution, y = 0 to 10.0;

[0010] R is an organic template agent, which has the structure shown in Formula II;

[0011]

[0012] Optionally, x is selected from any value of 0, 0.5, 1.0, 1.5, 2.0 or a range of values ​​between any two.

[0013] Optionally, y is selected from any value of 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 or a range of values ​​between any two.

[0014] Optionally, the molecular sieve has a three-dimensional 8*8*20-membered ring channel structure.

[0015] In this invention, three-dimensional 8*8*20 refers to having an 8-membered ring, an 8-membered ring, and a 20-membered ring in the three-dimensional direction.

[0016] Optionally, the molecular sieve is tetragonal and belongs to space group I4.

[0017] Optionally, the cell parameters are

[0018] Optionally, the molecular sieve particles are elongated (rectangular strips) with a length of 1 to 2 mm.

[0019] Optionally, the X-ray powder diffraction of the molecular sieve has diffraction peaks at at least the following positions;

[0020]

[0021]

[0022] Secondly, the present invention provides a method for preparing the above-mentioned molecular sieve DNL-14, the method comprising the following steps:

[0023] S1: A mixture of raw materials containing phosphorus source, aluminum source, silicon source, organic template agent, mineralizer, water and solvent is used to obtain a reaction gel;

[0024] S2: The reaction gel is heated and crystallized under sealed conditions to obtain molecular sieve powder.

[0025] Optionally, in step S1, the molar ratio of the organic template agent, phosphorus source, alcohol solvent, mineralizing agent, aluminum source, silicon source, and water in the reaction gel is:

[0026] aR: bH3PO4: cROH: d:HF:q Al2O3: m SiO2: nH2O;

[0027] Where a = 1 to 10.0, and the number of moles of the organic template agent is based on its own mole count;

[0028] b = 0.5~2.0, the number of moles of phosphorus source is expressed as the number of moles of H3PO4;

[0029] c = 20~60.0, the number of moles of alcohol solvent is based on the number of moles of its own ROH;

[0030] d = 1.0 to 6.0, the number of moles of mineralizer is expressed as the number of moles of HF;

[0031] q = 0.1~1.2, where the number of moles of aluminum source is expressed as the number of moles of Al2O3;

[0032] m = 0 to 1.0, where the number of moles of silicon source is expressed as the number of moles of SiO2;

[0033] n = 5 to 30, and the number of moles of water is expressed as the number of moles of H2O.

[0034] Optionally, 'a' is selected from any value of 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 or a range of values ​​between any two.

[0035] Optionally, b is selected from any value among 0.5, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.8, and 2.0, or a range between any two.

[0036] Optionally, c is independently selected from any value among 20, 25, 30, 35, 40, 45, 50, 55, 60 or a range of values ​​between any two.

[0037] Optionally, d is independently selected from any value of 1, 2, 3, 4, 5, 6 or a range of values ​​between any two.

[0038] Optionally, q is independently selected from any value among 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2 or a range of values ​​between any two.

[0039] Optionally, m is independently selected from any value among 0, 0.1, 0.15, 0.2, 0.3, 0.5, 0.6, 0.8, 0.9, 1.0 or a range of values ​​between any two.

[0040] Optionally, n is independently selected from any value among 5.0, 6.0, 7.0, 8.0, 9.0, 10.0, 20.0, and 30.0, or a range of values ​​between any two.

[0041] Optionally, the organic template agent is 1,8-bis(dimethylaminonaphthalene).

[0042] Optionally, the alcohol solvent is selected from at least one of cyclohexanol, ethylene glycol, diethylene glycol, and triethylene glycol; preferably triethylene glycol.

[0043] Optionally, the mineralizing agent is a fluoride-containing compound.

[0044] Optionally, the phosphorus source is selected from phosphoric acid and / or phosphorus pentoxide.

[0045] Optionally, the aluminum source is selected from at least one of boehmite, aluminum hydroxide, and aluminum isopropoxide.

[0046] Optionally, the silicon source is selected from at least one of silica sol, tetraethyl orthosilicate, tetramethoxysilane, and silica.

[0047] Optionally, in step S2, the crystallization temperature is 80–240°C, and the crystallization time is 1–60 days.

[0048] Optionally, the crystallization temperature is independently selected from any value or a range between any two of 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, 160°C, 170°C, 180°C, 190°C, 200°C, 210°C, 220°C, 230°C, and 240°C.

[0049] Optionally, the crystallization time is independently selected from any value or a range between 1d, 5d, 10d, 15d, 20d, 25d, 30d, 35d, 40d, 45d, 50d, 55d, and 60d.

[0050] Optionally, in step S1, the phosphorus source and solvent are mixed, then an aluminum source is added, followed by an organic template agent to obtain an initial gel mixture, and then hydrofluoric acid is added and stirred at 500 rpm to obtain the reaction gel.

[0051] Optionally, the molecular sieve powder is calcined to remove the template agent to obtain the molecular sieve DNL-14; the calcination temperature is 500-600℃ and the calcination time is 3-5h.

[0052] Optionally, in step S2, the crystallized product is washed and dried to obtain the molecular sieve powder.

[0053] Optionally, the crystallization is carried out in a stainless steel high-pressure reactor.

[0054] Optionally, the drying is performed by drying in air at 90–110°C.

[0055] This invention obtains a novel three-dimensional 8*8*20-membered ring channel structure of aluminosilicate phosphate molecular sieve DNL-14 by designing the reaction ratio of each component and selecting a specific organic template agent, 1,8-bis(dimethylaminonaphthalene), under reasonable crystallization conditions.

[0056] Compared with the prior art, the present invention has the following beneficial effects:

[0057] 1) This invention synthesizes a novel molecular sieve with a framework structure.

[0058] 2) The preparation method provided by this invention has a simple synthesis process and is highly operable. Attached Figure Description

[0059] Figure 1 This is the X-ray powder diffraction (XRD) pattern of the product obtained in Example 1 of this invention;

[0060] Figure 2 This is a scanning electron microscope (SEM) image of the product obtained in Example 1 of the present invention. Detailed Implementation

[0061] The present application is further illustrated below with reference to specific embodiments. The following descriptions are merely a few embodiments of the present application and are not intended to limit the present application in any way. Although the present application discloses preferred embodiments as follows, they are not intended to limit the present application. Any modifications or variations made by those skilled in the art without departing from the scope of the technical solution of the present application using the disclosed technical content are equivalent to equivalent implementation cases and all fall within the scope of the technical solution.

[0062] Unless otherwise specified, the raw materials used in the embodiments of this application are all purchased commercially and used directly without any special treatment.

[0063] The analysis method in the embodiments of this application is as follows:

[0064] Phase analysis of the samples was performed using X-ray powder diffraction (XRD) with a Cu target and a Kα light source. The instrument used was an X'Pert PRO X-ray diffractometer from PANalytical, Netherlands. Tested under conditions of 40KV voltage and 40mA current.

[0065] The composition of the samples was analyzed by X-ray fluorescence spectroscopy (XRF) on a Philips Magix-601 X-ray fluorescence spectrometer.

[0066] Sample morphology analysis was performed using a scanning electron microscope (SEM) with the instrument being a Hitachi SU8020 field emission scanning electron microscope.

[0067] The samples were thermally analyzed using a TAQ-600 thermal analyzer at a heating rate of 10℃ / min from room temperature to 900℃.

[0068] cRED data were acquired using a JEOL 2100Plus transmission electron microscope equipped with an EMSIS GmbH camera and an ASI Cheetah 120 detector.

[0069] Example 1: Preparation of Sample 1

[0070] 0.538 g of orthophosphoric acid (85%) was added to 10.38 g of triethylene glycol (99%) and mixed. Then, 0.951 g of aluminum isopropoxide (98%) was added and stirred until homogeneous. Next, 1.497 g of 1,8-bis(dimethylaminonaphthalene) (98%) was added and vigorously stirred (500 rpm) until homogeneous, obtaining an initial gel mixture. Then, 0.38 g of hydrofluoric acid (40%) was added. The mixture was transferred to a stainless steel high-pressure reactor and statically crystallized at 200 °C for 72 hours under autogenous pressure. After crystallization, the solid product was centrifuged, washed, and dried in air at 100 °C to obtain a white powder product.

[0071] The product was confirmed to be DNL-14 by X-ray powder diffraction and is designated as Sample 1. The X-ray powder diffraction (XRD) pattern of Sample 1 is shown below. Figure 1 As shown, the scanning electron microscope (SEM) images are as follows: Figure 2 As shown, the particles of sample 1 are rectangular strips with a length ranging from 1 mm to 2 mm. Meanwhile, the molecular sieve morphology is uniform in the SEM image, and the synthesized molecular sieve does not contain other phases, indicating high purity. XRF analysis and thermal analysis, after normalization, yielded the elemental composition of sample 1 as: (P... 48 Al 48 O 192 ).8R, where R is 1,8-bis(dimethylaminonaphthalene).

[0072] Table 1. X-ray powder diffraction characteristics of sample 1

[0073]

[0074]

[0075]

[0076] Example 2: Preparation of Sample 2

[0077] 0.539 g of orthophosphoric acid (85%) was added to 10.399 g of triethylene glycol (99%) and mixed. Then, 0.949 g of aluminum isopropoxide (98%) was added and stirred until homogeneous. Next, 2.996 g of 1,8-bis(dimethylaminonaphthalene) (98%) was added and vigorously stirred (500 rpm) until homogeneous, yielding an initial gel mixture. Then, 0.686 g of hydrofluoric acid (40%) was added. The mixture was transferred to a stainless steel high-pressure reactor and statically crystallized at 200 °C for 72 hours under autogenous pressure. After crystallization, the solid product was centrifuged, washed, and dried in air at 100 °C to obtain a white powder product. X-ray powder diffraction confirmed the presence of DNL-14 in the product, which was designated as Sample 2. The scanning electron microscope (SEM) image of Sample 2 was similar to that of Sample 1.

[0078] Example 3: Preparation of Sample 3

[0079] 0.541 g of orthophosphoric acid (85%) was added to 13.432 g of tetraethylene glycol (99%) and mixed. Then, 0.954 g of aluminum isopropoxide (98%) was added and stirred until homogeneous. Next, 1.498 g of 1,8-bis(dimethylaminonaphthalene) (98%) was added and vigorously stirred (500 rpm) until homogeneous, yielding an initial gel mixture. Then, 0.344 g of hydrofluoric acid (40%) was added. The mixture was transferred to a stainless steel high-pressure reactor and statically crystallized at 200°C for 72 hours under autogenous pressure. After crystallization, the solid product was centrifuged, washed, and dried in air at 100°C to obtain a white powder product. X-ray powder diffraction confirmed the presence of DNL-14 in the product, which was designated as Sample 3. The scanning electron microscope (SEM) image of Sample 3 was similar to that of Sample 1.

[0080] Example 4: Preparation of Sample 4

[0081] 0.533 g of orthophosphoric acid (85%) was added to 10.39 g of tetraethylene glycol (99%) and stirred. Then, 0.952 g of aluminum isopropoxide (98%) and 0.066 g of silica sol (60.08%) were added and stirred until homogeneous. Then, 3 g of 1,8-bis(dimethylaminonaphthalene) (98%) was added and stirred vigorously (500 rpm) until homogeneous, obtaining an initial gel mixture. Then, 0.683 g of hydrofluoric acid (40%) was added. The mixture was transferred to a stainless steel high-pressure reactor and statically crystallized at 200 °C for 72 hours under autogenous pressure. After crystallization, the solid product was centrifuged, washed, and dried in air at 100 °C to obtain a white powder product. X-ray powder diffraction confirmed the presence of DNL-14 in the product, which was designated as sample 4. The scanning electron microscope (SEM) image of sample 4 was similar to that of sample 1.

[0082] Structural Analysis of Example 5

[0083] Continuous rotational electron diffraction (cRED) was performed on samples 1-4. The structural analysis results indicate that DNL-14 crystallizes in the tetragonal crystal system, space group I4. The final refined cell parameters are as follows: Information about the molecular sieve framework can be obtained.

[0084] The above description is merely a few embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A molecular sieve DNL-14, characterized in that, The chemical composition of the molecular sieve is as follows: (Si x P 48-x Al 48 O 192 ).8R.yH2O of formula I; In Equation I, x represents the number of moles of Si. x P 48-x Al 48 O 192 The number of moles of Si in the sample, x = 0 ~ 2.

0. y represents the number of moles of Si x P 48-x Al 48 O 192 The number of moles of H2O in the solution, y = 0 ~ 10.0; R is an organic template agent, which has the structure shown in Formula II; Formula II.

2. The molecular sieve DNL-14 according to claim 1, characterized in that, The molecular sieve has a three-dimensional 8*8*20-membered ring channel structure; The molecular sieve is tetragonal and belongs to space group I4. The unit cell parameters are a = 21.8734~22.0230 Å and c = 14.4897~14.5900 Å. The molecular sieve particles are elongated and have a length of 1 to 2 mm.

3. The molecular sieve DNL-14 according to claim 1, characterized in that, The molecular sieve exhibits diffraction peaks at least at the following positions in X-ray powder diffraction; 4. A method for preparing the molecular sieve DNL-14 according to any one of claims 1 to 3, characterized in that, The preparation method includes the following steps: S1: A mixture of raw materials containing phosphorus source, aluminum source, silicon source, organic template agent, mineralizer, water and solvent is used to obtain a reaction gel; S2: The reaction gel is heated and crystallized under sealed conditions to obtain molecular sieve powder.

5. The method for preparing molecular sieve DNL-14 according to claim 4, characterized in that, In step S1, the molar ratio of the organic template agent, phosphorus source, alcohol solvent, mineralizing agent, aluminum source, silicon source, and water in the reaction gel is: aR: bH3PO4: cROH: d: HF: q Al2O3: m SiO2: nH2O; Where a = 1 ~ 10.0, the number of moles of the organic template agent is expressed as the number of moles of the agent itself; b = 0.5 ~ 2.0, the number of moles of phosphorus source is expressed as the number of moles of H3PO4; c = 20 ~ 60.0, the number of moles of alcohol solvent is based on the number of moles of its own ROH; d = 1.0 ~ 6.0, the number of moles of mineralizer is expressed as the number of moles of HF; q = 0.1 ~ 1.2, where the number of moles of aluminum source is expressed as the number of moles of Al2O3; m = 0 ~ 1.0, the number of moles of silicon source is expressed in terms of the number of moles of SiO2; n = 5 ~ 30, the number of moles of water is expressed as the number of moles of H2O.

6. The method for preparing molecular sieve DNL-14 according to claim 5, characterized in that, The organic template agent is 1,8-bis(dimethylaminonaphthalene); The alcohol solvent is selected from at least one of cyclohexanol, ethylene glycol, diethylene glycol, and triethylene glycol; The mineralizing agent is a compound containing fluoride ions.

7. The method for preparing molecular sieve DNL-14 according to claim 4, 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 boehmite, aluminum hydroxide and aluminum isopropoxide; The silicon source is selected from at least one of silica sol, tetraethyl orthosilicate, tetramethoxysilane, and silica.

8. The method for preparing molecular sieve DNL-14 according to claim 4, characterized in that, In step S2, the crystallization temperature is 80 ~ 240℃, and the crystallization time is 1 ~ 60 days.

9. The method for preparing molecular sieve DNL-14 according to claim 4, characterized in that, In step S1, the phosphorus source and solvent are mixed, then an aluminum source is added, followed by an organic template agent and hydrofluoric acid. The mixture is stirred at 500 rpm to obtain the reaction gel.

10. The application of the molecular sieve DNL-14 according to any one of claims 1 to 3 in adsorption separation.

11. A water adsorbent, characterized in that, The material of the water adsorbent includes a molecular sieve DNL-14 as described in any one of claims 1 to 3.

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