Molecular sieve, method for preparing the same, and use thereof

Abstract

The application relates to a molecular sieve and a preparation method and application thereof, which is named as DNL-11 by the applicant and belongs to the molecular sieve field. The chemical formula of the molecular sieve is (H2O) x R2(Si y Al 8‑ y P8O 32 F2), wherein x=0-10.0, y=0-2.0; the molecular sieve has a one-dimensional 16-membered ring pore channel structure; the synthesis process is simple and operable. The molecular sieve can be used for adsorption separation and has high water adsorption.

Description

TECHNICAL FIELD

[0001] The present application relates to a molecular sieve, a preparation method thereof and an application thereof in water adsorbents, which is named as DNL-11 by the applicant, and belongs to the field of molecular sieves. BACKGROUND

[0002] Phosphorus-aluminum molecular sieves are phosphorus-aluminum salts with regular pore channels or cage structures, which are composed of phosphorus-oxygen tetrahedrons and aluminum-oxygen tetrahedrons sharing oxygen vertices. They were successfully developed by UCC in 1982, greatly expanding the family of molecular sieves and becoming a milestone in the history of molecular sieves. The phosphorus-aluminum molecular sieve family has a large number of members, mainly because the phosphorus or aluminum in the phosphorus-aluminum molecular sieve can be easily isomorphously substituted by Si or Mg, etc., to generate silicon-aluminum phosphate molecular sieves (SAPO) and metal silicon-aluminum phosphate molecular sieves (MeAPO). At present, more than ten kinds of metal elements have been integrated into the phosphorus-aluminum molecular sieve family, and these molecular sieves have been widely used in the fields of adsorption and catalysis.

[0003] Phosphorus-aluminum molecular sieves are generally synthesized by hydrothermal synthesis. Since 1961, R.M. Barrer and P.J. Denny introduced organic templates into the hydrothermal synthesis system of molecular sieves, the design and introduction of organic templates greatly improved the number of artificially synthesized zeolites. However, so far, only 46 kinds of phosphorus-aluminum molecular sieves have been published by IZA, and the potential and prospect of exploring phosphorus-aluminum molecular sieves are still very huge.

[0004] Since the 19th century, researchers have been seeking to break through the 12-membered ring limit of molecular sieves, and have successfully broken through in the phosphorus-aluminum molecular sieve system. VFI is the first one-dimensional 18-membered ring super-large pore phosphorus-aluminum molecular sieve, but it is not thermally stable and is converted into AlPO-8. And up to now, there is only one kind of IFO structure with stable full connection of super-large pore phosphorus-aluminum molecular sieve, so we still lack understanding of the channel properties of super-large pore phosphorus-aluminum molecular sieves. SUMMARY

[0005] According to a first aspect of the present application, a new structure of molecular sieve DNL-11 with one-dimensional 16-membered ring channels is provided, which is of great significance for understanding the adsorption of phosphorus-aluminum molecular sieves and the catalytic and adsorption properties of super-large pore silicon-aluminum molecular sieves.

[0006] The molecular sieve has one-dimensional 16-membered ring channels;

[0007] The molecular sieve has X-ray powder diffraction peaks at least at the following positions.

[0008]

[0009] The chemical formula of the molecular sieve is (H2O) x R2(Siy Al 8-y P8O 32 F2),

[0010] wherein x = 0-10.0, y = 0-2.0;

[0011] R is a positive charge group of 4-pyrrolidinyl pyridine.

[0012] According to another aspect of the present application, there is provided a method for synthesizing the above-mentioned molecular sieve, comprising at least the following steps:

[0013] (1) mixing water, a phosphorus source, an aluminum source, a silicon source, an organic template agent, a mineralizing agent and a solvent to obtain a mixture;

[0014] (2) crystallizing the mixture obtained in (1) in a closed reaction kettle to obtain a crystallization product;

[0015] (3) calcining the crystallization product to remove the template agent to obtain the molecular sieve.

[0016] Optionally, the method comprises the following steps:

[0017] (1) mixing the phosphorus source, the aluminum source, the silicon source, the organic template agent, water, fluoride and alcohol in proportion under stirring to obtain a mixture, and the mixture forms a reaction gel;

[0018] (2) transferring the reaction gel to a stainless steel reaction kettle, and crystallizing at 130-200°C for 1-15 days under sealed conditions;

[0019] (3) washing and drying the crystallized product to obtain DNL-11;

[0020] The organic template agent is 4-pyrrolidinyl pyridine.

[0021] The phosphorus source is selected from phosphoric acid and / or diphosphorus pentoxide;

[0022] The aluminum source is selected from at least one of pseudoboehmite, aluminum hydroxide or aluminum isopropoxide;

[0023] The silicon source is selected from at least one of silica sol, tetraethyl orthosilicate, tetramethoxysilane or white carbon black;

[0024] The mineralizing agent is selected from HF and / or NH4F; the fluoride ion therein functions.

[0025] The solvent is selected from alcohol.

[0026] Optionally, the alcohol is selected from at least one of cyclohexanol, ethylene glycol, diethylene glycol, triethylene glycol.

[0027] the molar composition of the mixture is aR:bHF:cH3PO4:qSiO2:Al2O3:mROH:nH2O;

[0028] wherein R represents a positively charged group of an organic templating agent;

[0029] a = 0.1 to 5.0;

[0030] b = 1.0 to 5.0;

[0031] c = 0.5 to 5.0;

[0032] q = 0 to 1.0;

[0033] m = 0 to 100;

[0034] n = 5 to 100.

[0035] Optionally, a is independently selected from any of the values 0.1, 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 a range of values between any two of these values.

[0036] Optionally, b is independently selected from any of the values 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, 4.0, 4.2, 4.5, 4.8, 5.0 or a range of values between any two of these values.

[0037] Optionally, c is independently selected from any of the values 0.5, 0.8, 1.0, 1.1, 1.3, 1.6, 1.8, 2.0, 2.4, 2.6, 3.0, 3.3, 4.0, 4.2, 4.6, 5.0 or a range of values between any two of these values.

[0038] Optionally, q is independently selected from any of the values 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 a range of values between any two of these values.

[0039] Optionally, m is independently selected from any of the values 0, 10, 15, 20, 30, 40, 50, 60, 70, 80, 90, 100 or a range of values between any two of these values.

[0040] Optionally, n is independently selected from any of the values 5, 10, 20, 25, 30, 50, 60, 70, 80, 90, 100 or a range of values between any two of these values.

[0041] The temperature of the crystallization is 130-200℃.

[0042] Optionally, the temperature of the crystallization is independently selected from any value or a range between any two values of 130℃, 140℃, 150℃, 160℃, 170℃, 180℃, 190℃, 200℃.

[0043] The time of the crystallization is 1-15 days.

[0044] Optionally, the time of the crystallization is independently selected from any value or a range between any two values of 1d, 2d, 3d, 4d, 5d, 6d, 7d, 8d, 9d, 10d, 12d, 13d, 14d, 15d.

[0045] Optionally, the temperature of the crystallization is 150-200℃.

[0046] Optionally, the temperature of the crystallization is independently selected from any value or a range between any two values of 150℃, 160℃, 170℃, 180℃, 190℃, 200℃.

[0047] According to another aspect of the present application, there is provided an application of the above-mentioned molecular sieve as a water adsorption material.

[0048] According to another aspect of the present application, there is provided a water adsorption agent containing the above-mentioned molecular sieve or the molecular sieve prepared by the above-mentioned preparation method.

[0049] The water adsorption agent is used for water absorption and energy storage.

[0050] The water adsorption amount of the water adsorption agent can reach 350mg / g or above.

[0051] The beneficial effects that can be produced by the present application include:

[0052] 1) The present application synthesizes a new type of framework structure molecular sieve.

[0053] 2) The preparation method provided by the present application has a simple synthesis process and strong operability.

[0054] 3) The new type of framework structure molecular sieve prepared by the present application can be used for adsorption separation and has high water adsorption. BRIEF DESCRIPTION OF DRAWINGS

[0055] Figure 1 is the X-ray powder diffraction spectrum (XRD) of the product obtained in Example 1 of the present application.

[0056] Figure 2 is the scanning electron microscope image (SEM) of the product obtained in Example 1 of the present application.

[0057] Figure 3 is the water vapor isotherm adsorption curve of DNL-11 in Example 10 of the present application. DETAILED DESCRIPTION

[0058] The present application will be described in detail below with reference to Examples, but the present application is not limited to these Examples.

[0059] The raw materials in the Examples of the present application are all purchased through commercial channels unless otherwise specified.

[0060] The analysis method in the Examples of the present application is as follows:

[0061] The sample phase analysis is analyzed by X-ray powder diffraction (XRD), and the instrument used is X’Pert PRO X-ray diffractometer of PANAlytical Company, Netherlands, using Cu target, Kα light source 40KV voltage, 40mA current.

[0062] The sample composition is analyzed by X-ray fluorescence spectroscopy (XRF), and is determined on Magix-601 X-ray fluorescence spectrometer of Philips.

[0063] The sample morphology analysis is analyzed by scanning electron microscope (SEM), and the instrument used is Hitachi SU8020 field emission scanning electron microscope.

[0064] The thermal analysis of the sample is performed by TA Q-600 thermal analyzer at a temperature rising rate of 10℃ / min from room temperature to 900℃.

[0065] The water vapor adsorption test of the sample is performed by BSD-VVS multi-station gravimetric gas vapor adsorption instrument of Belsys at P / P0 of 0.8 and temperature of 25℃.

[0066] The cRED data is collected on JEOL 2100Plus transmission electron microscope equipped with EMSIS GmbH camera and ASI Cheetah120 detector.

[0067] Preparation of Example 1 Sample 1

[0068] A mixture of 0.524 g of orthophosphoric acid (85%) was added to 10.372 g of triethylene glycol and stirred, then 0.952 g of aluminum triisopropoxide (98%) was added and stirred until uniform, then 1.037 g of 4-pyrrolidinopyridine (98%) was added and stirred until uniform, then 0.11 g of hydrofluoric acid was added to obtain an initial gel mixture. The mixture was moved to a stainless steel autoclave and crystallized at 200°C for 72 hours under autogenous pressure. After the crystallization was completed, the solid product was centrifuged, washed, and dried in air at 100°C to obtain a white powder product. The product was confirmed to be DNL-11 by X-ray powder diffraction, and was recorded as sample 1. The X-ray powder diffraction pattern (XRD) of sample 1 is shown in Figure 1 , the scanning electron microscope (SEM) image is shown in Figure 2 , the morphology of sample 1 was a stick shape, and the size was 200 nm-200 μm. At the same time, the morphology of the molecular sieve in the SEM image was uniform, and the synthesized molecular sieve did not contain other phases, which reflected the high purity of the molecular sieve. XRF analysis and thermal analysis normalization obtained the elemental composition of sample 1: (H2O)8R2·(P8Al8O 32 F2) wherein R is 4-pyrrolidinopyridine.

[0069] The X-ray powder diffraction characteristics of sample 1 are shown in Table 1:

[0070]

[0071]

[0072] Preparation of sample 2 in Example 2

[0073] A mixture of 0.532 g of orthophosphoric acid (85%) was added to 10.373 g of triethylene glycol and stirred, then 0.949 g of aluminum triisopropoxide (98%) was added and stirred until uniform, then 1.038 g of 4-pyrrolidinopyridine (98%) was added and stirred until uniform, then 0.57 g of hydrofluoric acid was added to obtain an initial gel mixture. The mixture was moved to a stainless steel autoclave and crystallized at 200°C for 72 hours under autogenous pressure. After the crystallization was completed, the solid product was centrifuged, washed, and dried in air at 100°C to obtain a white powder product. The product was confirmed to be DNL-11 by X-ray powder diffraction, and was recorded as sample 2. The X-ray powder diffraction pattern (XRD) and scanning electron microscope (SEM) image of sample 2 were similar to those of sample 1.

[0074] Preparation of sample 3 in Example 3

[0075] An initial gel mixture was prepared by adding 0.278 g of orthophosphoric acid (85%) to 10.38 g of triethylene glycol with stirring, then adding 0.95 g of aluminum triisopropoxide (98%) with stirring until homogeneous, then adding 1.037 g of 4-pyrrolidinopyridine (98%) with vigorous stirring (500 rpm) until homogeneous, and finally adding 0.34 g of hydrofluoric acid. The mixture was transferred to a stainless steel autoclave and crystallized at 200 °C for 72 hours under autogenous pressure. After the crystallization was complete, the solid product was centrifuged, washed, and dried in air at 100 °C to yield a white powder product, which was identified as DNL-11 by X-ray powder diffraction and was labeled as Sample 3. The X-ray powder diffraction pattern (XRD) and scanning electron micrograph (SEM) of Sample 3 were similar to those of Sample 1.

[0076] Preparation of Example 4 Sample 4

[0077] An initial gel mixture was prepared by adding 1.051 g of orthophosphoric acid (85%) to 10.381 g of triethylene glycol with stirring, then adding 0.95 g of aluminum triisopropoxide (98%) with stirring until homogeneous, then adding 1.036 g of 4-pyrrolidinopyridine (98%) with vigorous stirring (500 rpm) until homogeneous, and finally adding 0.37 g of hydrofluoric acid. The mixture was transferred to a stainless steel autoclave and crystallized at 200 °C for 72 hours under autogenous pressure. After the crystallization was complete, the solid product was centrifuged, washed, and dried in air at 100 °C to yield a white powder product, which was identified as DNL-11 by X-ray powder diffraction and was labeled as Sample 4. The X-ray powder diffraction pattern (XRD) and scanning electron micrograph (SEM) of Sample 4 were similar to those of Sample 1.

[0078] Preparation of Example 5 Sample 5

[0079] An initial gel mixture was prepared by adding 0.685 g of orthophosphoric acid (85%) to 9.495 g of diethylene glycol with stirring, then adding 1.217 g of aluminum triisopropoxide (98%) with stirring until homogeneous, then adding 1.041 g of 4-pyrrolidinopyridine (98%) with vigorous stirring (500 rpm) until homogeneous, and finally adding 0.34 g of hydrofluoric acid. The mixture was transferred to a stainless steel autoclave and crystallized at 200 °C for 72 hours under autogenous pressure. After the crystallization was complete, the solid product was centrifuged, washed, and dried in air at 100 °C to yield a white powder product, which was identified as DNL-11 by X-ray powder diffraction and was labeled as Sample 5. The X-ray powder diffraction pattern (XRD) and scanning electron micrograph (SEM) of Sample 5 were similar to those of Sample 1.

[0080] Preparation of Example 6 Sample 6

[0081] To 8.932 g of ethylene glycol was added 1.093 g of orthophosphoric acid (85%) with stirring, followed by 1.975 g of aluminum triisopropoxide (98%) with stirring until homogeneous, then 2.152 g of 4-pyrrolidinopyridine (98%) with vigorous stirring (500 rpm) until homogeneous, and finally 1.186 g of hydrofluoric acid to yield the initial gel mixture. The mixture was transferred to a stainless steel autoclave and 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 yield a white powder product, which was confirmed by X-ray powder diffraction to be DNL-11, labeled as Sample 6. The X-ray powder diffraction pattern (XRD) and scanning electron micrograph (SEM) of Sample 6 were similar to those of Sample 1.

[0082] Example 7 Preparation of Sample 7

[0083] To 9.043 g of ethylene glycol was added 0.673 g of orthophosphoric acid (85%) with stirring, followed by 1.215 g of aluminum triisopropoxide (98%) with stirring until homogeneous, then 1.324 g of 4-pyrrolidinopyridine (98%) with vigorous stirring (500 rpm) until homogeneous, and finally 0.438 g of hydrofluoric acid to yield the initial gel mixture. The mixture was transferred to a stainless steel autoclave and 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 yield a white powder product, which was confirmed by X-ray powder diffraction to be DNL-11, labeled as Sample 7. The X-ray powder diffraction pattern (XRD) and scanning electron micrograph (SEM) of Sample 7 were similar to those of Sample 1.

[0084] Example 8 Preparation of Sample 8

[0085] To 10.382 g of triethylene glycol and 1.363 g of water was added 0.528 g of orthophosphoric acid (85%) with stirring, followed by 0.95 g of aluminum triisopropoxide (98%) with stirring until homogeneous, then 1.039 g of 4-pyrrolidinopyridine (98%) with vigorous stirring (500 rpm) until homogeneous, and finally 0.336 g of hydrofluoric acid to yield the initial gel mixture. The mixture was transferred to a stainless steel autoclave and 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 yield a white powder product, which was confirmed by X-ray powder diffraction to be DNL-11, labeled as Sample 8. The X-ray powder diffraction pattern (XRD) and scanning electron micrograph (SEM) of Sample 8 were similar to those of Sample 1.

[0086] Example 9 Structure Analysis

[0087] Continuous rotational electron diffraction (cRED) was performed on samples 1-8. Structural analysis results indicate that DNL-11 crystallizes in a monoclinic crystal system, space group P21. The final refined cell parameters are as follows: β = 105.791. Information about the molecular sieve framework can be obtained.

[0088] Example 10: DNL-11 used for adsorption separation

[0089] This embodiment illustrates the use of DNL-11 as a water adsorbent. However, the molecular sieves of this application are not limited to water adsorption.

[0090] The samples obtained in Examples 1-8 were loaded into the adsorption apparatus and pretreated by heating at 250°C to constant weight. Then, the temperature was stabilized at 25°C using a constant-temperature water bath before water vapor adsorption testing was initiated. Typical experimental results are shown below. Figure 3 . Figure 3 The experimental results showed that when P / P0 was 0.8, the water vapor adsorption capacity was 356.126 mg / g. Other samples achieved similar results.

[0091] 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, characterized in that, the molecular sieve has one-dimensional 16-membered ring channels; 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 molecular sieve has the chemical formula (H2O) x R2(Si y Al 8-y P8O 32 F2), wherein x = 0-10.0, y = 0-2.0; R is a positive charge group of 4-pyrrolidinyl pyridine. 3.A method for preparing the molecular sieve according to any one of claims 1 or 2, characterized in that, at least comprising the following steps: (1) mixing water, a phosphorus source, an aluminum source, a silicon source, an organic template agent, a mineralizer and a solvent to obtain a mixture; (2) crystallizing the mixture obtained in (1) in a sealed reaction kettle to obtain a crystallization product; (3) calcining the crystallization product to remove the template agent to obtain the molecular sieve. 4.The method according to claim 3, characterized in that, the organic template agent is 4-pyrrolidinyl pyridine. 5.The 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 pseudoboehmite, aluminum hydroxide or aluminum isopropyl alcohol; the silicon source is selected from at least one of silica sol, tetraethyl orthosilicate, tetramethoxysilane or white carbon black; the mineralizer is selected from HF and / or NH4F; the solvent is selected from an alcohol. 6.The method according to claim 5, characterized in that the alcohol is selected from at least one of cyclohexanol, ethylene glycol, diethylene glycol and triethylene glycol. 7.The method according to claim 3, characterized in that, the molar composition of the mixture is aR:bHF:cH3PO4:qSiO2:Al2O3:mROH:nH2O; wherein, a＝0.1~5.0； b＝1.0~5.0； c＝0.5~5.0； q=0~1.0； m=0~100； n=5~100。 8.The method according to claim 3, characterized in that, the temperature of the crystallization is 130-200℃; the time of the crystallization is 1-15 days. 9.The method according to claim 3, characterized in that, the temperature of the crystallization is 150-200℃. 10.Use of the molecular sieve according to any one of claims 1 or 2, characterized in that, as a water adsorption material.

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