NON molecular sieve as well as preparation method and application thereof

Abstract

The invention discloses a NON molecular sieve as well as a preparation method and application thereof. The crystal morphology of the NON molecular sieve is a one-dimensional fibrous morphology, the average width of the crystal is 20-40nm, and the average length of the crystal is 1-2mu m. The molecular sieve is small in particle size, has a one-dimensional fibrous morphology, has the advantages of being simple in preparation method, low in cost and high in yield, can be applied as an adsorbent or a catalyst for conversion of organic compounds, and has good performance.

Description

Technical Field

[0001] This invention belongs to the field of NON molecular sieves, specifically relating to a pure silicon NON molecular sieve, its preparation method, and its application. Background Technology

[0002] Molecular sieve materials are a class of three-dimensional tetrahedral frameworks formed by primary structural units, TO4 ([SiO4], [AlO4], or [PO4], etc.), through shared vertices. Two T atoms are connected by oxygen bridges to form various secondary structures. These secondary structures combine in different ways to form chain structures and building blocks, ultimately stacking to create different molecular sieve topologies. Molecular sieve materials possess excellent hydrothermal stability, tunable pore diameter and shape, and variable pore chemical composition. These properties endow them with wide applications in adsorption, separation, catalysis, microelectronics, and medical diagnostics.

[0003] Non-Orthogonal (NOO) molecular sieves were first proposed by Mobil in the early 1980s. They are molecular sieves with an orthorhombic crystal structure and six-membered ring channels. The small pore size of NOO molecular sieves limits their application in macromolecular catalysis, but this very small pore size gives them advantages in the adsorption and storage of radioactive materials and selective catalysis of small molecules. They are generally widely used as adsorbents. NOO molecular sieves can be used for water purification and contaminated soil remediation to lock and remove toxic heavy metal ions; they also hold promise for extracting useful trace metals from salt lake brine, which is of great significance for solving water shortage problems and promoting socio-economic development and ecological environment construction.

[0004] CN107473239A discloses a method for synthesizing NON-type molecular sieves using tetraethylammonium hydroxide and trimethylethylammonium bromide as organic structure directing agents, resulting in molecular sieves with good hydrogen storage performance. CN115304075A discloses a method for synthesizing one-dimensional strip-shaped, rod-shaped, or needle-shaped NON-type molecular sieves using 4-dimethylaminopyridine and other organic structure directing agents, resulting in molecular sieves with good performance in organic compound conversion reactions.

[0005] Existing NON-type molecular sieves are either prepared using complex and expensive organic directing agents or by using multiple structural directing agents. The synthesis process of some NON-type molecular sieves requires multi-stage crystallization, which is complicated. Moreover, the average particle size of NON-type molecular sieves prepared by the above methods is generally 5 to 10 μm. Summary of the Invention

[0006] To address the problems existing in the prior art, this invention provides a non-non molecular sieve, its preparation method, and its applications. The molecular sieve has a small particle size and a one-dimensional fibrous morphology. It has the advantages of simple preparation method, low cost, and high yield, and can be used as an adsorbent or catalyst for the conversion of organic compounds, exhibiting excellent performance.

[0007] The first aspect of this invention provides a non-non molecular sieve. The molecular sieve has a one-dimensional fibrous morphology; the average width of the crystal is 20-40 nm, and the average length is 1-2 μm.

[0008] According to the present invention, the NON molecular sieve is an all-silica molecular sieve. The NON molecular sieve does not contain aluminum.

[0009] A second aspect of the present invention provides a method for preparing NON molecular sieves. The method includes:

[0010] A mixture of silicon source, fluorine source, organic structure directing agent and water is obtained by water distillation; then the mixture is subjected to a crystallization reaction to obtain the NON molecular sieve.

[0011] The organic structure directing agent has the following structural formula:

[0012] Among them, R1 is selected from C 1-8 Alkyl groups, preferably selected from C 1-4 Alkyl groups, more preferably selected from C 1-2 Alkyl; R2 - For OH - At least one of the following: halogen anions.

[0013] According to the present invention, in the organic structure directing agent, R1 is preferably methyl or ethyl; R2 - Preferably OH - .

[0014] According to the present invention, in the feeding process, the molar ratio of silicon source (SiO2), organic structure directing agent (abbreviated as OSDA), fluorine source (F), and water is SiO2:OSDA:F:H2O = 1:(0.03~0.8):(0.5~3.0):(10~30), preferably 1:(0.03~0.7):(0.5~1.5):(10~25), and more preferably 1:(0.10~0.6):(0.5~1.0):(10~22).

[0015] According to the present invention, the silicon source is selected from at least one of silicic acid, silica gel, silica sol, tetraethyl silicate, and water glass; the fluorine source is at least one of hydrofluoric acid and ammonium fluoride.

[0016] According to the present invention, the mixture does not contain alkali metals or alkaline earth metals. No alkali source is added in the preparation method of the molecular sieve. The alkali source can be, for example, an alkaline substance other than silicon sources and organic structure directing agents; specifically, any alkali source conventionally used in the art for the purpose of making the system alkaline; more specifically, inorganic bases with alkali metals or alkaline earth metals as cations, particularly sodium hydroxide and potassium hydroxide. Here, "not containing an alkali source" means that no alkali source is intentionally or actively introduced into the mixture.

[0017] According to the present invention, in the method for preparing the molecular sieve, the raw materials do not contain seed crystals, that is, no seed crystals are added.

[0018] According to the present invention, in the method for preparing the molecular sieve, the raw materials do not contain an aluminum source, that is, no aluminum source is added.

[0019] According to the present invention, the method of water treatment is rotary evaporation or open heating for water removal; the open heating treatment conditions are heating and stirring at 40 to 100°C, preferably at 45 to 80°C.

[0020] According to the present invention, in the mixture obtained after water distillation, the molar ratio of silicon source (SiO2) to water is 1:(3-9), preferably 1:(4-8).

[0021] According to the present invention, the crystallization conditions are as follows: crystallization at 100–200°C for 3–18 days, preferably at 110–190°C for 4–17 days, and more preferably at 120–180°C for 5–16 days. Crystallization is preferably performed at a rotation speed of 10–40 rpm. After crystallization, washing can be performed until the pH value is near neutral (pH = 7–8).

[0022] According to the present invention, drying is required after crystallization. The drying conditions are 60–180°C for 5–24 hours.

[0023] According to the present invention, the molecular sieve can be calcined as needed to remove template agents and any present moisture. The calcination can be carried out in any manner conventionally known in the art, for example, the calcination temperature is generally 300–900°C, preferably 400–700°C, more preferably 450–600°C; the calcination time is generally 2–9 hours, preferably 3–6 hours. Furthermore, the calcination is generally carried out in an oxygen-containing atmosphere, such as air or an oxygen atmosphere.

[0024] According to the present invention, the molecular sieve has a one-dimensional fibrous morphology; the average width of the crystal is 20-40 nm and the average length is 1-2 μm.

[0025] According to the present invention, the molecular sieve is an all-silica molecular sieve. The NON molecular sieve does not contain aluminum.

[0026] A third aspect of the present invention provides a NON molecular sieve composition comprising any of the aforementioned NON molecular sieves or NON molecular sieves prepared according to any of the aforementioned preparation methods, and a binder.

[0027] The fourth aspect of the present invention provides the use of any of the aforementioned NON molecular sieves, or NON molecular sieve compositions, or NON molecular sieves prepared according to any of the aforementioned preparation methods as adsorbents and / or catalysts.

[0028] Compared with the prior art, the main advantages of the present invention include:

[0029] 1. The NON molecular sieve of the present invention has a one-dimensional fibrous morphology, with an average crystal width of 20-40 nm and an average length of 1-2 μm. Compared with existing NON molecular sieves, the molecular sieve of the present invention has a smaller crystal size, does not contain other heteroatoms, and is more preferably an all-silica molecular sieve.

[0030] 2. The preparation method of the NON molecular sieve of the present invention uses a specific structure-directing agent OSDA, and further preferably limits the raw material feeding ratio. The synthesis method of the molecular sieve of the present invention is simple, uses inexpensive raw materials, can be produced on a large scale industrially, and can be used as an adsorbent or a catalyst for the conversion of organic compounds. It has good performance and has achieved good technical results.

[0031] 3. The NON molecular sieve provided by this invention can be used as an adsorbent or a catalyst for the conversion of organic compounds. Attached Figure Description

[0032] Figure 1 The X-ray diffraction (XRD) pattern of the sample in Example 1;

[0033] Figure 2 The image shown is a scanning electron microscope (SEM) image of the sample in Example 1.

[0034] Figure 3 The X-ray diffraction (XRD) pattern of the sample in Comparative Example 1 is shown.

[0035] Figure 4 The image shows the X-ray diffraction (XRD) pattern of the sample in Comparative Example 2. Detailed Implementation

[0036] The specific embodiments of the present invention will be described in detail below. However, it should be noted that the scope of protection of the present invention is not limited to these specific embodiments.

[0037] In this invention, the structure of the molecular sieve is determined by X-ray diffraction (XRD), which is measured using an X-ray powder diffractometer with a Cu-Kα ray source and a nickel filter. Before sample testing, the crystallization of the molecular sieve sample is observed using a scanning electron microscope (SEM) to confirm that the sample contains only one type of crystal, i.e., the molecular sieve sample is a pure phase. Based on this, XRD testing is then performed to ensure that there are no interfering peaks from other crystals in the diffraction patterns of the XRD spectrum.

[0038] In this invention, the scanning electron microscope (SEM) used for observing the molecular sieves in the following examples and comparative examples is a model S-4800II field emission scanning electron microscope. The molecular sieves were observed using this SEM at a magnification of 40,000x. A randomly selected field of view was used to calculate the average length of all crystals within that field of view. This operation was repeated 10 times. The average length of the crystals was taken as the 10 averages, and the average width of the crystals was calculated using the same method.

[0039] In this invention, the room temperature in each example is 20°C.

[0040] In this invention, the organic structure directing agent OSDA used in each embodiment has the following structural formula:

[0041]

[0042] In Examples 1, 2, and 3, R1 is ethyl, and R2 is... - For OH - ;

[0043] In Examples 4 and 5, R1 is methyl, and R2 is... - For OH - .

[0044] In Example 6, R1 is ethyl, and R2 is... - For Cl - .

[0045] Example 1

[0046] Deionized water, organic structure-directing agent OSDA, silica sol, and hydrofluoric acid were mixed evenly. The amount of organic structure-directing agent OSDA in the feed was 0.05 mol; the molar ratio of the materials was: OSDA / SiO2 = 0.5; F / SiO2 = 0.5; H2O / SiO2 = 20.

[0047] After stirring at room temperature for 5 hours, the raw material liquid was stirred in an open container at 80°C, and then treated with water distillation to obtain a mixture. In the mixture, the molar ratio of H2O / SiO2 = 5.

[0048] The mixture was placed in a stainless steel reactor and crystallized for 10 days at 170°C and 30 rpm. After crystallization, the mixture was centrifuged and washed until the pH value was near neutral (pH = 7-8), and then dried in an oven at 110°C for 8 hours to obtain the molecular sieve.

[0049] The XRD pattern of the molecular sieve is as follows: Figure 1 As shown, this is a non-non-metallic molecular sieve with a yield of 80 wt%. The SEM image of the molecular sieve is shown below. Figure 2 As shown, the molecular sieve has a one-dimensional fibrous morphology, with an average crystal width of 30 nm and an average length of 1.5 μm.

[0050] Example 2

[0051] Deionized water, organic structure-directing agent OSDA, silica sol, and hydrofluoric acid were mixed evenly. The amount of organic structure-directing agent OSDA in the feed was 0.04 mol; the molar ratio of the materials was: OSDA / SiO2 = 0.4; F / SiO2 = 1; H2O / SiO2 = 15.

[0052] After stirring at room temperature for 5 hours, the raw material liquid was stirred in an open container at 80°C, and then treated with water distillation to obtain a mixture. In the mixture, the molar ratio of H2O / SiO2 = 5.

[0053] The mixture was placed in a stainless steel reactor and crystallized for 8 days at 180°C and 30 rpm. After crystallization, the mixture was centrifuged and washed until the pH value was near neutral (pH = 7-8), and then dried in an oven at 110°C for 10 hours to obtain the molecular sieve.

[0054] The XRD pattern of the molecular sieve and Figure 1 Similarly, it is a non-non type molecular sieve, with a yield of 85 wt%; the SEM image of the molecular sieve is similar to... Figure 2 Similarly, molecular sieves have a one-dimensional fibrous morphology, with an average crystal width of 20 nm and an average length of 1 μm.

[0055] Example 3

[0056] Deionized water, organic structure-directing agent OSDA, silica sol, and hydrofluoric acid were mixed evenly. The amount of organic structure-directing agent OSDA in the feed was 0.03 mol; the molar ratio of the materials was: OSDA / SiO2 = 0.3; F / SiO2 = 0.8; H2O / SiO2 = 18.

[0057] After stirring at room temperature for 5 hours, the raw material liquid was stirred in an open container at 80°C. The water was then evaporated to obtain a mixture. The molar ratio of H₂O / SiO₂ in the mixture was 6.

[0058] The mixture was placed in a stainless steel reactor and crystallized for 14 days at 150°C and 30 rpm. After crystallization, the mixture was centrifuged and washed until the pH value was near neutral (pH = 7-8), and then dried in an oven at 110°C for 9 hours to obtain the molecular sieve.

[0059] The XRD pattern of the molecular sieve and Figure 1 As shown, this is a non-non-metallic molecular sieve with a yield of 81 wt%; the SEM image of the molecular sieve is similar to... Figure 2 Similarly, the molecular sieve has a one-dimensional fibrous morphology, with an average crystal width of 40 nm and an average length of 1.6 μm.

[0060] Example 4

[0061] Deionized water, organic structure-directing agent OSDA, silica sol, and hydrofluoric acid were mixed evenly. The amount of organic structure-directing agent OSDA in the feed was 0.03 mol; the molar ratio of the materials was: OSDA / SiO2 = 0.3; F / SiO2 = 0.8; H2O / SiO2 = 22.

[0062] After stirring at room temperature for 5 hours, the raw material liquid was stirred in an open container at 80°C, and then treated with water distillation to obtain a mixture. In the mixture, the molar ratio of H2O / SiO2 = 5.

[0063] The mixture was placed in a stainless steel reactor and crystallized for 12 days at 150°C and 30 rpm. After crystallization, the mixture was centrifuged and washed until the pH value was near neutral (pH = 7-8), and then dried in an oven at 110°C for 12 hours to obtain the molecular sieve.

[0064] The XRD pattern of the molecular sieve and Figure 1 Similarly, it is a non-non type molecular sieve, with a yield of 83 wt%; the SEM image of the molecular sieve is similar to... Figure 2 Similarly, the molecular sieve has a one-dimensional fibrous morphology, with an average crystal width of 38 nm and an average length of 1.5 μm.

[0065] Example 5

[0066] Deionized water, organic structure-directing agent OSDA, tetraethyl silicate, and hydrofluoric acid were mixed evenly. The amount of organic structure-directing agent OSDA in the feed was 0.04 mol; the molar ratio of the materials was: OSDA / SiO2 = 0.4; F / SiO2 = 1.0; H2O / SiO2 = 20.

[0067] After stirring at room temperature for 5 hours, the raw material liquid was stirred in an open container at 80°C, and then treated with water distillation to obtain a mixture. In the mixture, the molar ratio of H2O / SiO2 = 5.

[0068] The mixture was placed in a stainless steel reactor and crystallized for 10 days at 160°C and 30 rpm. After crystallization, the mixture was centrifuged and washed until the pH value was near neutral (pH = 7-8), and then dried in an oven at 150°C for 8 hours to obtain the molecular sieve.

[0069] The XRD pattern of the molecular sieve and Figure 1 Similarly, it is a non-non type molecular sieve, with a yield of 81 wt%; the SEM image of the molecular sieve is similar to... Figure 2 Similarly, the molecular sieve has a one-dimensional fibrous morphology, with an average crystal width of 39 nm and an average length of 1.5 μm.

[0070] Example 6

[0071] The difference from Example 1 lies in the use of a different organic structure-directing agent. In Example 6, the organic structure-directing agent OSDA has the following structural formula:

[0072]

[0073] Wherein, R1 is ethyl, and R2 is Cl. - .

[0074] Deionized water, organic structure-directing agent OSDA, silica sol, and hydrofluoric acid were mixed evenly. The amount of organic structure-directing agent OSDA in the feed was 0.05 mol; the molar ratio of the materials was: OSDA / SiO2 = 0.5; F / SiO2 = 0.5; H2O / SiO2 = 18.

[0075] After stirring at room temperature for 5 hours, the raw material liquid was stirred in an open container at 80°C, and then treated with water distillation to obtain a mixture. In the mixture, the molar ratio of H2O / SiO2 = 5.

[0076] The mixture was placed in a stainless steel reactor and crystallized for 10 days at 170°C and 30 rpm. After crystallization, the mixture was centrifuged and washed until the pH value was near neutral (pH = 7-8), and then dried in an oven at 110°C for 8 hours to obtain the molecular sieve.

[0077] The XRD pattern of the molecular sieve is similar to Figure 1 It is a non-non-type molecular sieve, with a yield of 79 wt%; the SEM image of the molecular sieve is similar to... Figure 2 The molecular sieve has a one-dimensional fibrous morphology, with an average crystal width of 39 nm and an average length of 1.9 μm.

[0078] Comparative Example 1

[0079] The raw materials and preparation steps are the same as in Example 1, except that the raw material ratios are adjusted. In the feeding process, the organic structure-directing agent OSDA is 0.1 mol. The molar ratio of the materials is: OSDA / SiO2 = 1; F / SiO2 = 0.5; H2O / SiO2 = 20.

[0080] After stirring at room temperature for 5 hours, the raw material liquid was stirred in an open container at 80°C, and then treated with water distillation to obtain a mixture. In the mixture, the molar ratio of H2O / SiO2 = 5.

[0081] The other steps are the same as in Example 1. Molecular sieves are then prepared.

[0082] The XRD pattern of the molecular sieve is as follows: Figure 3 As shown, the sample is uncrystallized, has an amorphous structure, and is not a NON molecular sieve.

[0083] Comparative Example 2

[0084] The difference from Example 3 lies in the directing agent. In this example, 1,4-diazabicyclo[2,2,2]octane is used instead of the organic directing agent OSDA in Example 3. The other steps are the same as in Example 3. A molecular sieve is thus prepared.

[0085] The XRD pattern of the molecular sieve is as follows: Figure 4 As shown, the sample is an MTW molecular sieve, not a NON molecular sieve.

[0086] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A NON molecular sieve characterized by, The NON molecular sieve has a one-dimensional fiber-like morphology, and the average width of the crystal is 20-40 nm and the average length is 1-2 microns.

2. The NON molecular sieve of claim 1, wherein, The NON molecular sieve is a full-silica molecular sieve.

3. A method of preparing a NON molecular sieve comprising: The NON molecular sieve is prepared by mixing a silicon source, a fluorine source, an organic structure directing agent and water, and then performing a water vapor treatment to obtain a mixture, and then performing a crystallization reaction on the mixture. The organic structure-directing agent has a structural formula: wherein R1is selected from C 1-8 alkyl, preferably selected from C 1-4 alkyl, more preferably selected from C 1-2 alkyl; R2 - is OH - at least one of a halide anion.

4. The preparation method according to claim 3, characterized in that, The molar ratio of the silicon source (calculated as SiO2), the organic structure directing agent, the fluorine source (calculated as F) and water is SiO2:OSDA:F:H2O=1:(0.03-0.8):(0.5-3.0):(10-30), preferably 1:(0.03-0.7):(0.5-1.5):(10-25), more preferably 1:(0.10-0.6):(0.5-1.0):(10-22); wherein the organic structure directing agent is denoted as OSDA.

5. The preparation method according to claim 3, characterized in that, The silicon source is selected from at least one of silicic acid, silica gel, silica sol, tetraethyl silicate and water glass. The fluorine source is at least one of hydrofluoric acid and ammonium fluoride.

6. The preparation method according to claim 3, characterized in that, The mixture does not contain alkali metals or alkaline earth metals.

7. The preparation method according to claim 3, characterized in that, The molar ratio of the silicon source (calculated as SiO2) and water in the mixture obtained after the water vapor treatment is 1:(3-9), preferably 1:(4-8).

8. The preparation method according to claim 3, characterized in that, The crystallization conditions are 100-200°C for 3-18 days, preferably 110-190°C for 4-17 days, more preferably 120-180°C for 5-16 days; further, the crystallization is preferably performed under rotation at 10-40 rpm.

9. The preparation method according to claim 3, characterized in that, Drying is performed after the crystallization; the drying conditions are 60-180°C for 5-24 hours.

10. A NON molecular sieve composition comprising the NON molecular sieve of claim 1 or 2 or prepared according to any one of claims 3-9, and a binder.

11. Use of the NON molecular sieve of claim 1 or 2 or prepared according to any one of claims 3-9 as an adsorbent and / or a catalyst.

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