A method for the synthesis and use of an all-silicon or heteroatom itth molecular sieve

Abstract

The present application belongs to the technical field of molecular sieve, and particularly relates to a synthesis method and application of a full-silicon or heteroatom ITH molecular sieve. The synthesis method of the full-silicon or heteroatom ITH molecular sieve comprises the following steps: 1) mixing a silicon source, a template agent, water and a fluorine source to obtain a gel mixture; or mixing a silicon source, a heteroatom source, a template agent, water and a fluorine source to obtain a gel mixture; 2) crystallizing the gel mixture obtained in step 1) to obtain the full-silicon or heteroatom ITH molecular sieve. The template agent of the present application can be used to synthesize full-silicon, silicon-aluminum, silicon-boron, silicon-gallium and titanium-silicon ITH molecular sieves in one step, and no expensive germanium species needs to be introduced. In addition, the full-silicon or heteroatom ITH molecular sieve prepared by the method of the present application has excellent catalytic activity and caprolactam selectivity in Beckmann rearrangement reaction.

Description

Technical Field

[0001] The present invention belongs to the technical field of molecular sieves, and in particular relates to a synthesis method and application of an all-silicon or heteroatom ITH molecular sieve. Background Art

[0002] In 2003, Professor Avelino Corma's research group at the Polytechnic University of Valencia, Spain, reported a novel all-silicon molecular sieve, ITQ-13, with a three-dimensional 10*10*9-membered ring structure, designated ITH. Due to its unique 9-membered ring pores, ITH molecular sieves have been shown to possess unique performance in reactions such as fluidized catalytic cracking and methanol-to-olefins, garnering widespread attention. However, the direct synthesis of heteroatom ITH molecular sieves, such as silicon-aluminum, in a single step is challenging. Researchers typically synthesize silicon-boron ITH molecular sieves, then remove the boron and supplement the aluminum to obtain aluminum-containing ITH molecular sieves. Alternatively, in addition to the heteroatom raw materials, expensive germanium species must be added.

[0003] In recent years, there have been more and more reports on ITH molecular sieves. For example, Xu Longya et al. used fumed silica instead of tetraethyl silicate as a silicon source and hexamethonium hydroxide as a template to synthesize an all-silica ITH molecular sieve (Microporous Mesoporous Mater. 2010, 129, 278–284.); Wu Qinming et al. used hexamethonium bromide as a template to synthesize an all-silica ITH molecular sieve in the solid phase (Chinese J. Org. Chem. 2017, 35, 572–576.); Xiao Fengshou et al. used a polyquaternary ammonium salt template to synthesize a silicon-alumina ITH molecular sieve in one step (Angew. Chem. Int. Ed. 2020, 59, 15649–15655.); Yang Weimin et al. used a pyrrolidine template to synthesize a silicon-germanium-alumina ITH molecular sieve in one step (Microporous Mesoporous Mater. 2021, 319, 111058.), but due to the use of the classic ITH molecular sieve template hexamethonium, heteroatoms cannot be introduced into the ITH molecular sieve framework; the polymer template has a complex structure, the degree of polymerization is difficult to control, and the reproducibility is poor; the synthesis of pyrrolidino templates requires the introduction of germanium species, and the synthesis of ITH molecular sieves still needs further improvement.

[0004] Therefore, it is of great practical significance to propose a new and structurally simple template molecule to achieve the one-step synthesis of all-silicon and heteroatom all-silicon or heteroatom ITH molecular sieves such as silicon-aluminum, silicon-boron, silicon-gallium, and titanium-silicon. Summary of the Invention

[0005] In view of the above-mentioned disadvantages of the prior art, the present application aims to provide a synthesis method and use of a full-silicon or heteroatom ITH molecular sieve to solve the problems in the preparation of the full-silicon or heteroatom ITH molecular sieve in the prior art, such as the inability of the traditional template to introduce heteroatoms, the complex structure of the polymer template, and the necessity of introducing germanium species for the pyrrolidine template, which leads to the decrease of the hydrothermal stability of the molecular sieve, the decrease of the crystallinity, and even the collapse of the structure.

[0006] The first aspect of the present application provides a template, wherein the template is N,N,N,N'-tetramethyl-N',N'-diethyl-1,6-hexanediammonium hydroxide, and the structural formula is

[0007] The second aspect of the present application provides a synthesis method of a full-silicon or heteroatom ITH molecular sieve, comprising the following steps:

[0008] 1) mixing a silicon source, a template, water, and a fluorine source to obtain a gel mixture; or mixing a silicon source, a heteroatom source, a template, water, and a fluorine source to obtain a gel mixture;

[0009] 2) crystallizing the gel mixture obtained in step 1) to obtain a full-silicon or heteroatom ITH molecular sieve.

[0010] In some embodiments of the present application, the silicon source in step 1) is selected from one or more of fumed silica, silica sol, tetramethyl orthosilicate, tetraethyl orthosilicate, and silica gel.

[0011] In some embodiments of the present application, the heteroatom source in step 1) is selected from one or more of an aluminum source, a boron source, a gallium source, or a titanium source.

[0012] In some embodiments of the present application, the fluorine source in step 1) is selected from hydrofluoric acid and / or ammonium fluoride.

[0013] In some embodiments of the present application, the molar ratio of the silicon source, the template, water, and the fluorine source in step 1) is 1:0.25:(1-10):(0.5-1).

[0014] In some embodiments of the present application, the molar ratio of the silicon source, the heteroatom source, the template, water, and the fluorine source in step 1) is 1:(0-0.017):0.25:(1-10):(0.5-1), preferably, the molar ratio of the silicon source, the heteroatom source, the template, water, and the fluorine source is 1:(0.0025-0.017):0.25:(1-10):(0.5-1).

[0015] In some embodiments of the present application, the aluminum source is selected from one or more of boehmite, aluminum hydroxide, aluminum sulfate octadecahydrate, and aluminum isopropylate.

[0016] In some embodiments of the present invention, the boron source is boric acid.

[0017] In some embodiments of the present invention, the gallium source is selected from one or more of gallium nitrate, gallium chloride and gallium oxide.

[0018] In some embodiments of the present invention, the titanium source is tetrabutyl titanate.

[0019] In some embodiments of the present invention, the crystallization in step 2) is carried out in a reactor, wherein a seed crystal is provided in the reactor; the seed crystal is an ITH molecular sieve.

[0020] In some embodiments of the present invention, the crystallization temperature in step 2) is 160-200° C.; and the crystallization time is 24-168 h.

[0021] In some embodiments of the present invention, the mass of the seed crystal accounts for 1%-30% of the mass of the silicon source in step 1) converted into the mass of SiO2.

[0022] In some embodiments of the present invention, after the crystallization in step 2) is completed, post-treatment is performed to obtain an all-silicon or heteroatom ITH molecular sieve.

[0023] The third aspect of the present invention provides an all-silicon or heteroatom ITH molecular sieve obtained by the above synthesis method.

[0024] In some embodiments of the present invention, the post-treatment includes washing, drying, and calcining; the drying temperature is 80-120°C; and the calcining temperature is 550-600°C.

[0025] In some embodiments of the present invention, when the heteroatom source is an aluminum source, the silicon-to-aluminum ratio of the all-silicon or heteroatom ITH molecular sieve is ≥50.

[0026] In some embodiments of the present invention, when the heteroatom source is a boron source, the silicon-boron ratio of the all-silicon or heteroatom ITH molecular sieve is ≥30.

[0027] In some embodiments of the present invention, when the heteroatom source is a gallium source, the silicon-gallium ratio of the all-silicon or heteroatom ITH molecular sieve is ≥50.

[0028] In some embodiments of the present invention, when the heteroatom source is a gallium source, the silicon-to-titanium ratio of the all-silicon or heteroatom ITH molecular sieve is ≥50.

[0029] In some embodiments of the present invention, the all-silicon or heteroatom ITH molecular sieve is a large-sized crystal with a size of (7-35)×(1-4)×(0.1-1) μm.

[0030] The application also provides a use of the all-silicon or heteroatom ITH molecular sieve as a catalyst in a chemical reaction.

[0031] In some embodiments of the application, the chemical reaction comprises Beckmann rearrangement, methanol to olefins, or catalytic cracking of 1-hexene.

[0032] The application has the following beneficial effects:

[0033] 1) The application uses N,N,N,N'-tetramethyl-N',N'-diethyl-1,6-hydroxyl hexanediammonium as a template agent, which can be used to synthesize all-silicon or heteroatom ITH molecular sieves in one step, and does not need to introduce expensive germanium species, compared with the classical template agent hexamethonium hydroxide of all-silicon or heteroatom ITH molecular sieves.

[0034] 2) The all-silicon or heteroatom ITH molecular sieves prepared by the method of the application have a larger adjustable range of silicon-aluminum ratio, silicon-boron ratio, silicon-gallium ratio, and silicon-titanium ratio, and the silicon-aluminum ratio, silicon-gallium ratio, and silicon-titanium ratio are not less than 50, and the silicon-boron ratio is not less than 30. The controllable aluminum, boron, gallium, and titanium contents make the number of acid sites and redox active centers in the all-silicon or heteroatom ITH molecular sieves controllable, thereby realizing the customization of the functions of the molecular sieves to meet the needs of different reaction processes, and having a wider application space.

[0035] 3) The all-silicon or heteroatom ITH molecular sieves prepared by the method of the application have excellent catalytic activity and caprolactam selectivity in Beckmann rearrangement. BRIEF DESCRIPTION OF DRAWINGS

[0036] Figure 1 A liquid H nuclear magnetic spectrum of the template agent in Example 1 of the application is shown.

[0037] Figure 2 A liquid C nuclear magnetic spectrum of the template agent in Example 1 of the application is shown.

[0038] Figure 3 An XRD spectrum of the all-silicon or heteroatom ITH molecular sieve obtained in Example 1 of the application is shown.

[0039] Figure 4 A SEM photo of the all-silicon or heteroatom ITH molecular sieve obtained in Example 1 of the application is shown.

[0040] Figure 5 A N2 adsorption curve of the all-silicon or heteroatom ITH molecular sieve obtained in Example 1 of the application is shown.

[0041] Figure 6 An XRD spectrum of the silicon-aluminum all-silicon or heteroatom ITH molecular sieve obtained in Example 4 of the application is shown.

[0042] Figure 7 A solid-state aluminum NMR spectrum of the silica-alumina all-silica or heteroatom ITH molecular sieve obtained in Example 4 of the present application is shown.

[0043] Figure 8 An XRD spectrum of the silica-boron all-silica or heteroatom ITH molecular sieve obtained in Example 7 of the present application is shown.

[0044] Figure 9 An XRD spectrum of the silica-gallium all-silica or heteroatom ITH molecular sieve obtained in Example 11 of the present application is shown.

[0045] Figure 10 An XRD spectrum of the titanium-silica all-silica or heteroatom ITH molecular sieve obtained in Example 14 of the present application is shown.

[0046] Figure 11 A Beckmann rearrangement activity plot of the all-silica or heteroatom ITH molecular sieve in Example 1 of the present application is shown. DETAILED DESCRIPTION

[0047] Hereinafter, specific embodiments of the all-silica or heteroatom ITH molecular sieve and the method for synthesizing and use thereof will be described in detail.

[0048] Before further description of the specific embodiments of the present application, it is to be understood that the application is not limited to the particular specific embodiments described below; it is also to be understood that the terminology used in the following description is for purposes of describing the particular specific embodiments only and is not intended to limit the scope of the present application. Unless otherwise defined, all technical and scientific terms used in the present application have the same meaning as commonly understood by one of ordinary skill in the art. In addition, although specific methods, devices, and materials are named or described in the present application, any methods, devices, and materials similar or equivalent to those described herein can be used in the practice of the present application.

[0049] When numerical ranges are given, it should be understood that every numerical range encompasses any number falling within the range, unless otherwise indicated. Unless otherwise defined, all technical and scientific terms used in the present application have the same meaning as commonly understood by one of ordinary skill in the art. In addition, although specific methods, devices, and materials are named or described in the present application, any methods, devices, and materials similar or equivalent to those described herein can be used in the practice of the present application, in accordance with the teachings of the present application, based on the state of the art at the time of the patent filing, and as such

[0050] ITH molecular sieve (also known as ITH structured molecular sieve) is a crystalline microporous material composed of four tetrahedrons (e.g., silicon, aluminum, phosphorus, etc.) sharing corners. It has uniform micropores and molecular-sized cavities. Its unique pore structure not only effectively regulates acid sites and redox active centers, but also greatly improves reaction activity and selectivity. It is widely used in petrochemicals, environmental treatment, and polymer synthesis.

[0051] After long-term experimental research, the inventors of the present application found that by using a small molecule organic ammonium template, such as N,N,N,N'-tetramethyl-N',N'-diethyl-1,6-diammonium hydroxide, a one-step crystallization method can be used to obtain all-silicon, silicon-aluminum ratio, silicon-boron ratio, silicon-gallium ratio, and silicon-titanium ratio. All-silicon or heteroatom ITH molecular sieves with adjustable ranges can be obtained. Traditional hexamethylammonium templates cannot directly synthesize heteroatom all-silicon or heteroatom ITH molecular sieves (heteroatoms are aluminum, boron, gallium, and titanium). This advantage greatly enhances the possibility of subsequent industrial application of the present invention. The preparation method of the present application is simple, easy to operate, and low in cost, and the number of active centers of the all-silicon or heteroatom ITH molecular sieve obtained is controllable. On this basis, the present invention has been completed.

[0052] In a specific embodiment of the present invention, the XRD data of the all-silicon or heteroatom ITH molecular sieve is measured using a German Bruker D2Advance X-ray diffractometer to characterize the crystal structure of the molecular sieve; the SEM image is obtained by a JEOL 7800 Prime field emission scanning electron microscope to characterize the morphology of the molecular sieve.

[0053] In a specific embodiment of the present invention, the molecular sieve (referring to a single crystal) exhibits a native crystal morphology of nanosheets or nanoparticles when observed using a scanning electron microscope (SEM). The crystal morphology refers to the external shape of a single molecular sieve crystal within the field of view of the scanning electron microscope. The term "native" refers to the structure of the molecular sieve as it objectively and directly presents after preparation, and does not refer to the structure of the molecular sieve that is artificially processed after manufacture.

[0054] The first aspect of the present invention provides a template agent, wherein the template agent is N,N,N,N'-tetramethyl-N',N'-diethyl-1,6-hexanediammonium hydroxide, and its structural formula is

[0055] The template provided by the present invention can be prepared, for example, by the following method 1 or method 2:

[0056] Method 1:

[0057] Dissolve 1-bromo-6-(trimethylammonium)hexyl bromide and N,N-diethylmethylamine in a sufficient amount of acetonitrile, heat at 60°C for condensation reflux, and stir overnight. After the reaction, wash the product with a sufficient amount of diethyl ether and dry it in vacuo at room temperature to obtain N,N,N,N'-tetramethyl-N',N'-diethyl-1,6-hexanediammonium bromide;

[0058] Dissolve N,N,N,N'-tetramethyl-N',N'-diethyl-1,6-hexanediammonium bromide in an appropriate amount of water, add a strong alkaline anion exchange resin to completely convert the bromide ions in N,N,N,N'-tetramethyl-N',N'-diethyl-1,6-hexanediammonium bromide into hydroxide ions, remove the resin by filtration, and rotary evaporate to obtain N,N,N,N'-tetramethyl-N',N'-diethyl-1,6-hexanediammonium hydroxide solution.

[0059] Method 2:

[0060] Dissolve trimethylamine, N,N-diethylmethylamine, and 1,6-dibromohexane in a sufficient amount of acetonitrile, heat at 60°C to reflux under condensation, and stir overnight. After the reaction, wash the product with a sufficient amount of ether and dry it in vacuo at room temperature to obtain N,N,N,N'-tetramethyl-N',N'-diethyl-1,6-hexanediammonium bromide;

[0061] Dissolve N,N,N,N'-tetramethyl-N',N'-diethyl-1,6-hexanediammonium bromide in an appropriate amount of water, add a strong alkaline anion exchange resin to completely convert the bromide ions in N,N,N,N'-tetramethyl-N',N'-diethyl-1,6-hexanediammonium bromide into hydroxide ions, remove the resin by filtration, and rotary evaporate to obtain N,N,N,N'-tetramethyl-N',N'-diethyl-1,6-hexanediammonium hydroxide solution.

[0062] The second aspect of the present invention provides a method for synthesizing all-silicon or heteroatom ITH molecular sieves, comprising the following steps:

[0063] 1) mixing a silicon source, a template, water and a fluorine source to obtain a gel mixture; or mixing a silicon source, a heteroatom source, a template, water and a fluorine source to obtain a gel mixture;

[0064] 2) The gel mixture obtained in step 1) is crystallized to obtain an all-silicon or heteroatom ITH molecular sieve.

[0065] In the synthesis method of the all-silicon or heteroatom ITH molecular sieve provided by the present invention, step 1) a silicon source, a template, water, and a fluorine source are mixed to obtain a gel mixture; or a silicon source, a heteroatom source, a template, water, and a fluorine source are mixed to obtain a gel mixture. Specifically, the silicon source, template, water, and fluorine source are mixed, or the silicon source, heteroatom source, template, water, and fluorine source are stirred at room temperature to evaporate the water to the desired amount, thereby obtaining a gel mixture.

[0066] In step 1) of the present application, the silicon source is selected from one or more of fumed silica, silica sol, tetramethyl orthosilicate, tetraethyl orthosilicate and silica gel.

[0067] In step 1) of the present application, the heteroatom source is selected from one or more of an aluminum source, a boron source, a gallium source or a titanium source. In the detailed description of the present application, the aluminum source is selected from one or more of boehmite, aluminum hydroxide, aluminum sulfate octadecahydrate and aluminum isopropoxide; the boron source is boric acid; the gallium source is selected from one or more of gallium nitrate, gallium chloride and gallium oxide; and the titanium source is tetrabutyl titanate.

[0068] In step 1) of the present application, the fluorine source is selected from hydrofluoric acid and / or ammonium fluoride.

[0069] In a specific embodiment of the present invention, the molar number of silicon is the molar number of SiO2 obtained by converting the mass of the silicon source. For example, when the silicon source is tetramethyl orthosilicate, the molar number of silicon (tetramethyl orthosilicate forms SiO2 upon hydrolysis, expressed as SiO2) = the mass of tetramethyl orthosilicate / the relative molecular weight of tetramethyl orthosilicate. The molar number of aluminum, boron, gallium, or titanium is the molar number of Al2O3, B2O3, or Ga2O3 obtained by converting the mass of the aluminum source, boron source, gallium source, or titanium source, respectively. In step 1) of the present invention, the molar ratio of the silicon source, template, water, and fluorine source in step 1) is 1:0.25:(1-10):(0.5-1); preferably, 1:0.25:1:0.5, 1:0.25:5:0.5, or 1:0.25:10:1. The molar ratio of the silicon source, heteroatom source, template, water and fluorine source is 1: (0-0.017): 0.25: (1-10): (0.5-1), which can be 1: 0: 0.25: (1-5): 0.5, 1: 0: 0.25: (5-10): 0.5, 1: 0: 0.25: (1-5): (0.5-1), 1: (0.0025-0.017): 0.25: (1-10): (0.5-1), 1: (0.00 25-0.005):0.25:(1-10):(0.5-1),1:(0.0025-0.005):0.25:(1-5):(0.5-1),1:(0.0025-0.005):0.25:(5-10):(0.5-1),1:(0.005-0.01):0.25:(1-10):(0.5-1),1:(0.005-0.01):0.25:(1-5):(0 .5-1), 1: (0.005-0.01): 0.25: (5-10): (0.5-1), 1: (0.01-0.017): 0.25: (1-10): (0.5-1), 1: (0.01-0.017): 0.25: (1-5): (0.5-1), 1: (0.01-0.017): 0.25: (5-10): (0.5-1), preferably 1: 0: 0.25: (1-10): ( 0.5-1), 1:(0.0025-0.017):0.25:(1-10):(0.5-1), more preferably 1:0:0.25:1:0.5, 1:0:0.25:5:0.5, 1:0:0.25:10:1, 1:0.0025:0.25:1:0.5, 1:0.005:0.25:5:0.5, 1:0.01:0.25:10:1 or 1:0.017:0.25:10:1.

[0070] Step 2) of the present invention is to crystallize the gel mixture obtained in step 1) to obtain an all-silicon or heteroatom ITH molecular sieve. Specifically, the gel mixture obtained in step 1) is crystallized in a sealed reactor. After crystallization, the all-silicon or heteroatom ITH molecular sieve is obtained by washing, drying, and calcining.

[0071] In step 2) of the present invention, the reactor is provided with a seed crystal, and the seed crystal is an ITH molecular sieve. The ITH molecular sieve seed crystal can be, for example, a completely crystallized ITH molecular sieve containing a template or an ITH molecular sieve that has been calcined at high temperature to remove the template. The ITH molecular sieve seed crystal of the present invention can be prepared, for example, by referring to the method described in (Angew. Chem. Int. Ed. 2003, 42, 1156–1159.). In a specific embodiment of the present invention, the ITH molecular sieve seed crystal is prepared by the synthesis method of the all-silicon or heteroatom ITH molecular sieve provided by the present invention (without heteroatoms).

[0072] In step 2) of the present invention, the mass of the seed crystal accounts for 1%-30% of the mass of the silicon source in step 1) converted into the mass of SiO2, which can be optionally 1-5%, 5-10%, 10-15%, 15-20%, 20-25%, 25-30%, 5-15%, 10-20% or 20-30%, etc., and is preferably 5% or 10%.

[0073] In step 2) of the present invention, the crystallization refers to the synthesis of all-silicon or heteroatom ITH molecular sieves under both dynamic and static rotation. The temperature of the crystallization is 160-200°C, which can be optionally 160-175°C or 175-200°C, preferably 160°C or 175°C. The reason why the temperature of the crystallization of the present invention is controlled within this range is that if the crystallization temperature is too high, the template will decompose and form a heterophase zeolite, which will lead to a decrease in the purity of the molecular sieve and weaken the catalytic activity and selectivity of the molecular sieve; if the temperature is too low (such as 100°C), amorphous powder will be produced, resulting in the inability to form a molecular sieve.

[0074] In step 2) of the present invention, the time of crystallization is 24-168h, which can be optionally 24-48h, 48-72h, 72-96h, 96-144h, 144-168h, 24-72h, 24-96h, 72-96h, 96-168h or 72-168h, etc., preferably 48h, 96h or 168h. The reason why the time of crystallization of the present invention is controlled under this range is that the crystallization time is too long to convert all-silicon or heteroatom ITH molecular sieve into a dense phase without pore structure, so that the molecular sieve loses screening and catalytic ability; the crystallization time is too short (such as 12h), and all-silicon or heteroatom ITH molecular sieve may not be fully formed, which will cause mixed amorphous substances in the product. This amorphous substance lacks an ordered pore structure and cannot provide ideal catalysis and separation performance.

[0075] In step 2) of the present invention, the washing, drying, and calcining are conventional techniques in the art. The drying temperature is 80-120°C, optionally 80-100°C or 100-120°C, preferably 80°C, 100°C, or 120°C. The calcining temperature is 550-600°C, preferably 550°C or 600°C.

[0076] The third aspect of the present invention provides an all-silicon or heteroatom ITH molecular sieve obtained by the above-mentioned synthesis method.

[0077] In the all-silicon or heteroatom ITH molecular sieve provided by the present invention, when the heteroatom source is an aluminum source, the silicon-to-aluminum ratio of the all-silicon or heteroatom ITH molecular sieve is ≥50, preferably 50-200, more preferably 50 or 100.

[0078] When the heteroatom source is a boron source, the silicon-boron ratio of the all-silicon or heteroatom ITH molecular sieve is ≥30, and can be selected from 30-200, preferably 30-50, 50-100, 100-200, 30-100 or 100-200, and more preferably 30, 50 or 100.

[0079] When the heteroatom source is a gallium source, the silicon-gallium ratio of the all-silicon or heteroatom ITH molecular sieve is ≥50, and can be selected from 50-200, preferably 50-100 or 100-200, and more preferably 50 or 100.

[0080] When the heteroatom source is a titanium source, the silicon-titanium ratio of the all-silicon or heteroatom ITH molecular sieve is ≥50, preferably 50-200, preferably 50-100 or 100-200, more preferably 50 or 100.

[0081] The all-silicon or heteroatom ITH molecular sieve provided by the present invention is a large-size crystal, that is, the molecular sieve material is a single crystal material with a larger size, and the internal structure is a continuous lattice without grain boundaries. The size of the all-silicon or heteroatom ITH molecular sieve is (7-35) × (1-4) × (0.1-1) μm, which can be optionally (7-17) × (1-1.63) × (0.1-0.48) μm, (17-35) × (1.63-4) × (0.48-1), (7-17) × (1-2) × (0.1-0.48) μm, (17-35) × (1-2) × (0.48-1) μm, preferably 7 × 2 × 0.48 μm or 17 × 1.63 × 0.48 μm.

[0082] In the all-silicon or heteroatom ITH molecular sieve provided by the present invention, the morphology of the all-silicon or heteroatom ITH molecular sieve is flaky or blocky; the topological structure of the all-silicon or heteroatom ITH molecular sieve is ITH (a molecular sieve structure type code named by the International Molecular Sieve Association).

[0083] According to prior art, different chemical reactions have different catalyst requirements. By regulating the acidic sites, the acidic strength and density of the molecular sieve can be adjusted to adapt to different acid-catalyzed reactions. By regulating the redox active centers, the activity and selectivity of the molecular sieve in oxidation and reduction reactions can be optimized, improving the catalytic efficiency. The adjustable aluminum, boron, gallium, and titanium contents of the present invention allow the number of acidic sites and redox active centers in the all-silicon or heteroatom ITH molecular sieve to be controlled, thereby achieving the function of customizing the molecular sieve to meet the needs of different reaction processes and having a broader application space.

[0084] The present invention also provides the use of all-silicon or heteroatom ITH molecular sieves as catalysts in chemical reactions, such as Beckmann rearrangement, methanol to olefins, or catalytic cracking of 1-hexene.

[0085] The Beckmann rearrangement described in this invention is an organic rearrangement reaction in which a ketoxime is converted to an amide under the action of an acid. The all-silicon or heteroatom ITH molecular sieves of this invention, with their relatively weak acidic sites, can provide a suitable acidic environment for the Beckmann rearrangement reaction, promoting the formation and stabilization of reaction intermediates, thereby improving yield and selectivity.

[0086] The methanol-to-olefins process described in the present invention converts methanol into light olefins (such as ethylene and propylene). The porous structure and adjustable acid sites of the all-silicon or heteroatom ITH molecular sieve of the present invention and the unique 9-membered ring pore structure of ITH help to reduce the diffusion limitation of the reaction process, improve the olefin yield, and reduce the formation of by-products.

[0087] The catalytic cracking of 1-hexene described herein refers to the process of converting 1-hexene into smaller olefins or other organic products through a catalytic cracking reaction. During this process, the pore structure and redox-active centers of the all-silicon or heteroatom ITH molecular sieves of the present invention facilitate efficient cracking reactions, producing smaller olefins while exhibiting excellent thermal stability and durability.

[0088] In order to make the technical means, creative features, objectives and effects achieved by the present invention easier to understand, the present invention is described in detail below with reference to embodiments and drawings.

[0089] In the following examples, unless otherwise stated, all reaction raw materials are commercially available products.

[0090] Unless otherwise specified, the purity of each product in each embodiment of the present invention exceeds 98%.

[0091] Example 1

[0092] The template agent N,N,N,N'-tetramethyl-N',N'-diethyl-1,6-hexanediammonium hydroxide in Example 1 of the present invention was prepared by method 1:

[0093] (1) 1-bromo-6-(trimethylammonium)hexyl bromide and N,N-diethylmethylamine are dissolved in a sufficient amount of acetonitrile, wherein the molar ratio of 1-bromo-6-(trimethylammonium)hexyl bromide and N,N-diethylmethylamine is as follows:

[0094] 1-Bromo-6-(trimethylammonium)hexyl bromide: N,N-diethylmethylamine = 1:1.5 (the molar amount of N,N-diethylmethylamine is greater than the molar amount of 1-bromo-6-(trimethylammonium)hexyl bromide to ensure sufficient reaction);

[0095] Heat to 60°C, condense and reflux, stir overnight. After the reaction, wash the product with sufficient ether and dry it in vacuo at room temperature to obtain N,N,N,N'-tetramethyl-N',N'-diethyl-1,6-hexanediammonium bromide;

[0096] (2) Dissolve the N,N,N,N'-tetramethyl-N',N'-diethyl-1,6-hexanediammonium bromide obtained in step 1) in an appropriate amount of water, add a strong alkaline anion exchange resin to completely convert the bromide ions in the N,N,N,N'-tetramethyl-N',N'-diethyl-1,6-hexanediammonium bromide into hydroxide ions, remove the resin by filtration, and rotary evaporate to obtain an N,N,N,N'-tetramethyl-N',N'-diethyl-1,6-hexanediammonium hydroxide solution with a concentration of 1 mmol / g.

[0097] The H NMR of the N,N,N,N'-tetramethyl-N',N'-diethyl-1,6-hexanediammonium hydroxide solution prepared by the above method is as follows: Figure 1 As shown, C NMR Figure 2 shown.

[0098] In this Example 1, the preparation of all-silicon ITH molecular sieve includes the following steps:

[0099] 1) Tetraethyl silicate, N,N,N,N'-tetramethyl-N',N'-diethyl-1,6-hexanediammonium hydroxide (Method 1), and hydrofluoric acid are mixed as the silicon source, template (R), and fluorine source, respectively, and stirred at room temperature to evaporate water to a predetermined ratio to obtain a gel mixture. The molar ratios of the silicon source, template, water, and hydrogen fluoride are as follows:

[0100] SiO2:R:H2O:HF=1.0:0.25:1:0.5.

[0101] 2) Transfer the product to a reactor and crystallize it at 160° C. for 168 h. After the crystallization is completed, cool the crystallized product, filter it, wash it, dry it at 80° C., and calcine it at 550° C. to obtain an all-silicon ITH molecular sieve.

[0102] The obtained all-silicon ITH molecular sieve was characterized by XRD, SEM and N2 adsorption. Figure 3 、 4 and 5.

[0103] XRD characterization results show that the all-silicon ITH molecular sieve obtained in this application has the characteristic diffraction peaks of ITH molecular sieves and is a pure all-silicon ITH molecular sieve; SEM shows that the all-silicon ITH molecular sieve obtained in this application is a block crystal with a smooth crystal surface and a size of about 17*1.63*0.48μm; nitrogen adsorption results show that its BET is 418.71m 2 / g, micropore volume is 0.15cm 3 / g.

[0104] Based on the above characterization results, it is proved that the method of the present application can prepare an all-silicon ITH molecular sieve with high crystallinity.

[0105] Beckmann rearrangement catalytic performance test:

[0106] The all-silicon ITH molecular sieve obtained in Example 1 was used to perform a Beckmann rearrangement catalytic performance test using a fixed-bed catalytic reaction apparatus line analyzer.

[0107] The test conditions are as follows: 0.3 g of 40-60 mesh catalyst was weighed and loaded into a reaction tube (inner diameter 8 mm), pretreated in a nitrogen atmosphere (80 ml / min) at atmospheric pressure and 400°C for 30 min, activated by passing anhydrous ethanol at a flow rate of 0.1 ml / min for 30 min, and then switched to a 35 wt.% cyclohexanone oxime ethanol solution for reaction. During the reaction, the pressure was atmospheric pressure, the temperature was maintained at 380°C, and the mass space velocity was 6 h -1 The products were analyzed by Agilent GC 8090 gas chromatograph equipped with an FID detector and an HP-INNOWAX capillary column.

[0108] Beckmann rearrangement reaction conversion and selectivity Figure 6 As shown, the all-silica ITH molecular sieve can maintain high cyclohexanone oxime conversion and caprolactam selectivity for a long time.

[0109] Example 2

[0110] In this embodiment 2, the preparation of all-silicon molecular sieve includes the following steps:

[0111] 1) Silica, N,N,N,N'-tetramethyl-N',N'-diethyl-1,6-hexanediammonium hydroxide (method 1) and ammonium fluoride as a silicon source, a template and a fluorine source, respectively, are mixed, and water is evaporated to a predetermined ratio by stirring at room temperature to obtain a gel mixture.

[0112] The molar ratios of silicon source, template, water and ammonium fluoride are as follows:

[0113] SiO2:R:H2O:NH4F=1.0:0.25:5:0.5.

[0114] 2) Transfer the mixture to a reactor and crystallize at 160° C. for 72 h. After the crystallization is completed, cool the crystallized product, filter, wash, dry at 100° C., and calcine at 550° C. to obtain an all-silicon ITH molecular sieve.

[0115] Example 3

[0116] In this embodiment 3, the preparation of all-silicon molecular sieve includes the following steps:

[0117] 1) 40 wt.% silica sol, N,N,N,N'-tetramethyl-N',N'-diethyl-1,6-hexanediammonium hydroxide (Method 1), and hydrofluoric acid as the silicon source, template, and fluorine source, respectively, were mixed and stirred at room temperature to evaporate water to a predetermined ratio to obtain a gel mixture. The molar ratios of the silicon source, template, water, and ammonium fluoride were as follows:

[0118] SiO2:R:H2O:HF=1.0:0.25:10:1.

[0119] 2) Transfer the mixture to a reactor and crystallize at 175° C. for 48 h. After the crystallization is completed, cool the crystallized product, filter, wash, dry at 120° C., and calcine at 600° C. to obtain an all-silicon ITH molecular sieve.

[0120] Example 4

[0121] In this Example 4, the all-silicon ITH molecular sieve obtained in Example 1 was added as a seed crystal to prepare an Al-ITH molecular sieve with a silicon-aluminum ratio of 200, comprising the following steps:

[0122] 1) Tetraethyl silicate, aluminum isopropoxide, N,N,N,N'-tetramethyl-N',N'-diethyl-1,6-hexanediammonium hydroxide (Method 1), and hydrofluoric acid are mixed as the silicon source, aluminum source, template, and fluorine source, respectively, and stirred at room temperature to evaporate water to a predetermined ratio to obtain a gel mixture. The molar ratios of the silicon source, aluminum source, template, water, and hydrogen fluoride are as follows:

[0123] SiO2:Al2O3:R:H2O:HF=1.0:0.0025:0.25:1:0.5.

[0124] 2) Transfer the product to a reactor and crystallize it at 160° C. for 168 h. After the crystallization is completed, cool the crystallized product, filter, wash, dry at 80° C., and calcine at 550° C. to obtain Al-ITH molecular sieve.

[0125] The obtained Al-ITH molecular sieve was characterized by XRD. Figure 7 , proving that highly crystalline Al-ITH molecular sieves can be synthesized.

[0126] The Al-ITH molecular sieve was characterized by solid-state NMR. Figure 8 , which proves that the coordination state of aluminum in the Al-ITH molecular sieve material obtained in this application is framework aluminum.

[0127] Example 5

[0128] In this Example 5, the all-silicon ITH molecular sieve obtained in Example 1 was added as a seed crystal to prepare an Al-ITH molecular sieve with a silicon-aluminum ratio of 100, comprising the following steps:

[0129] 1) Mixing white carbon black, aluminum sulfate 18-hydrate, N,N,N,N'-tetramethyl-N',N'-diethyl-1,6-hexanediammonium hydroxide (Method 1), and ammonium fluoride as the silicon source, aluminum source, template, and fluorine source, respectively, and stirring at room temperature to evaporate water to a predetermined ratio to obtain a gel mixture. The molar ratios of the silicon source, aluminum source, template, water, and ammonium fluoride are as follows:

[0130] SiO2:Al2O3:R:H2O:NH4F=1.0:0.005:0.25:5:0.5.

[0131] 2) Transfer the mixture to a reactor and crystallize at 160° C. for 72 h. After the crystallization is completed, cool the crystallized product, filter, wash, dry at 100° C., and calcine at 550° C. to obtain Al-ITH molecular sieve.

[0132] Example 6

[0133] In this Example 6, the whole silicon obtained in Example 1 was added as a seed crystal to prepare an Al-ITH molecular sieve with a silicon-to-aluminum ratio of 50, comprising the following steps:

[0134] 1) Tetraethyl silicate, boehmite, N,N,N'-tetramethyl-N',N'-diethyl-1,6-hexanediammonium hydroxide (Method 1), and hydrofluoric acid are mixed as the silicon source, aluminum source, template, and fluorine source, respectively, and stirred at room temperature to evaporate water to a predetermined ratio to obtain a gel mixture. The molar ratios of the silicon source, aluminum source, template, water, and ammonium fluoride are as follows:

[0135] SiO2:Al2O3:R:H2O:HF=1.0:0.01:0.25:10:1.

[0136] 2) Transfer the mixture to a reactor and crystallize at 175° C. for 48 h. After the crystallization is completed, cool the crystallized product, filter, wash, dry at 120° C., and calcine at 600° C. to obtain Al-ITH molecular sieve.

[0137] Example 7

[0138] In this Example 7, the all-silicon molecular sieve obtained in Example 1 was added as a seed crystal to prepare a B-ITH molecular sieve with a silicon-boron ratio of 200, comprising the following steps:

[0139] 1) Tetraethyl silicate, boric acid, N,N,N'-tetramethyl-N',N'-diethyl-1,6-hexanediammonium hydroxide (Method 1), and hydrofluoric acid are mixed as the silicon source, boron source, template, and fluorine source, respectively, and stirred at room temperature to evaporate water to a predetermined ratio to obtain a gel mixture. The molar ratios of the silicon source, boron source, template, water, and hydrogen fluoride are as follows:

[0140] SiO2:B2O3:R:H2O:HF=1.0:0.0025:0.25:1:0.5.

[0141] 2) Transfer the mixture to a reactor and crystallize at 160° C. for 168 h. After the crystallization is completed, cool the crystallized product, filter, wash, dry at 80° C., and calcine at 550° C. to obtain a B-ITH molecular sieve.

[0142] The obtained B-ITH molecular sieve was characterized by XRD. Figure 9 , proving that highly crystalline B-ITH molecular sieves can be synthesized.

[0143] Example 8

[0144] In this Example 8, the all-silicon molecular sieve obtained in Example 1 was added as a seed crystal to prepare a B-ITH molecular sieve with a silicon-boron ratio of 100, comprising the following steps:

[0145] 1) The silica source, boron source, template agent and fluorine source were mixed with 30.5 wt.% white carbon black, boric acid, N,N,N,N'-tetramethyl-N',N'-diethyl-1,6-hexanediammonium hydroxide (Method 1) and ammonium fluoride, respectively, and stirred at room temperature to evaporate water to a predetermined proportion to obtain a gel mixture. The molar ratio of the silica source, boron source, template agent, water and ammonium fluoride is as follows:

[0146] SiO2: B2O3: R: H2O: NH4F = 1.0: 0.005: 0.25: 5: 0.5.

[0147] 2) Transfer to a reaction kettle, crystallize at 160°C for 72h, and after the crystallization is completed, cool, filter, wash, dry at 100°C, and calcine at 550°C to obtain the B-ITH molecular sieve.

[0148] Example 9

[0149] In this example 9, the all-silicon ITH molecular sieve obtained in Example 1 is added as a seed crystal to prepare a B-ITH molecular sieve with a silicon-boron ratio of 50, including the following steps:

[0150] 1) The silica source, boron source, template agent and fluorine source were mixed with tetraethyl orthosilicate, boric acid, N,N,N,N'-tetramethyl-N',N'-diethyl-1,6-hexanediammonium hydroxide (Method 1) and hydrofluoric acid, respectively, and stirred at room temperature to evaporate water to a predetermined proportion to obtain a gel mixture. The molar ratio of the silica source, boron source, template agent, water and ammonium fluoride is as follows:

[0151] SiO2: B2O3: R: H2O: HF = 1.0: 0.01: 0.25: 10: 1.

[0152] 2) Transfer to a reaction kettle, crystallize at 175°C for 48h, and after the crystallization is completed, cool, filter, wash, dry at 120°C, and calcine at 600°C to obtain the B-ITH molecular sieve.

[0153] Example 10

[0154] In this example 10, the all-silicon ITH molecular sieve obtained in Example 1 is added as a seed crystal to prepare a B-ITH molecular sieve with a silicon-boron ratio of 30, including the following steps:

[0155] 1) The silica source, boron source, template agent and fluorine source were mixed with tetraethyl orthosilicate, boric acid, N,N,N,N'-tetramethyl-N',N'-diethyl-1,6-hexanediammonium hydroxide (Method 1) and hydrofluoric acid, respectively, and stirred at room temperature to evaporate water to a predetermined proportion to obtain a gel mixture. The molar ratio of the silica source, boron source, template agent, water and ammonium fluoride is as follows:

[0156] SiO2: B2O3: R: H2O: HF = 1.0: 0.017: 0.25: 10: 1.

[0157] 2) Transfer to the reactor, crystallization at 175°C for 24h, after crystallization, the crystallization product is cooled, filtered, washed, dried at 100°C, calcined at 600°C, to obtain B-ITH molecular sieve.

[0158] Example 11

[0159] In this example 11, the full-silicon ITH molecular sieve obtained in example 1 is added as seed crystal to prepare Ga-ITH molecular sieve with silicon-gallium ratio of 200, including the following steps:

[0160] 1) The tetraethyl silicate, gallium nitrate, N,N,N,N'-tetramethyl-N',N'-diethyl-1,6- hexanediammonium hydroxide (Method 1) and hydrofluoric acid are mixed as silicon source, gallium source, template agent and fluorine source respectively, and stirred at room temperature to evaporate water to a predetermined proportion to obtain a gel mixture. The molar ratio of silicon source, gallium source, template agent, water and hydrogen fluoride is as follows:

[0161] SiO2: Ga2O3: R: H2O: HF = 1.0: 0.0025: 0.25: 1: 0.5.

[0162] 2) Transfer to the reactor, crystallization at 160°C for 168h, after crystallization, the crystallization product is cooled, filtered, washed, dried at 80°C, calcined at 550°C, to obtain Ga-ITH molecular sieve.

[0163] The obtained Ga-ITH molecular sieve is characterized by XRD, and the results are shown in Figure 10 , which proves that high crystallinity Ga-ITH molecular sieve can be synthesized.

[0164] Example 12

[0165] In this example 12, the full-silicon ITH molecular sieve obtained in example 1 is added as seed crystal to prepare Ga-ITH molecular sieve with silicon-gallium ratio of 100, including the following steps:

[0166] 1) The white carbon black, gallium oxide, N,N,N,N'-tetramethyl-N',N'-diethyl-1,6- hexanediammonium hydroxide (Method 1) and ammonium fluoride are mixed as silicon source, gallium source, template agent and fluorine source respectively, and stirred at room temperature to evaporate water to a predetermined proportion to obtain a gel mixture. The molar ratio of silicon source, gallium source, template agent, water and ammonium fluoride is as follows:

[0167] SiO2: Ga2O3: R: H2O: NH4F = 1.0: 0.005: 0.25: 5: 0.5.

[0168] 2) Transfer the mixture to a reactor and crystallize at 160° C. for 72 h. After the crystallization is completed, cool the crystallized product, filter, wash, dry at 100° C., and calcine at 550° C. to obtain Ga-ITH molecular sieve.

[0169] Example 13

[0170] In this Example 13, the all-silicon ITH molecular sieve obtained in Example 1 was added as a seed crystal to prepare a Ga-ITH molecular sieve with a silicon-gallium ratio of 50, including the following steps:

[0171] 1) Tetraethyl silicate, gallium chloride, N,N,N,N'-tetramethyl-N',N'-diethyl-1,6-hexanediammonium hydroxide (Method 1), and hydrofluoric acid are mixed as the silicon source, gallium source, template, and fluorine source, respectively, and stirred at room temperature to evaporate water to a predetermined ratio to obtain a gel mixture. The molar ratios of the silicon source, gallium source, template, water, and ammonium fluoride are as follows:

[0172] SiO2:Ga2O3:R:H2O:HF=1.0:0.01:0.25:10:1.

[0173] The mixture was transferred to a reactor and crystallized at 175° C. for 48 h. After the crystallization, the crystallized product was cooled, filtered, washed, dried at 120° C., and calcined at 600° C. to obtain Ga-ITH molecular sieve.

[0174] Example 14

[0175] In this Example 14, the all-silicon ITH molecular sieve obtained in Example 1 was added as a seed crystal to prepare a Ti-ITH molecular sieve with a silicon-titanium ratio of 200, comprising the following steps:

[0176] 1) Tetraethyl silicate, tetrabutyl titanate, N,N,N,N'-tetramethyl-N',N'-diethyl-1,6-hexanediammonium hydroxide (Method 1) and hydrofluoric acid are mixed as the silicon source, titanium source, template, and fluorine source, respectively, and stirred at room temperature to evaporate water to a predetermined ratio to obtain a gel mixture. The molar ratios of the silicon source, titanium source, template, water, and hydrogen fluoride are as follows:

[0177] SiO2:TiO2:R:H2O:HF=1.0:0.0025:0.25:1:0.5.

[0178] 2) Transfer the product to a reactor and crystallize it at 160° C. for 168 h. After the crystallization is completed, cool the crystallized product, filter, wash, dry it at 80° C., and calcine it at 550° C. to obtain a Ti-ITH molecular sieve.

[0179] The obtained Ti-ITH molecular sieve was characterized by XRD. Figure 11, proving that highly crystalline Ti-ITH molecular sieves can be synthesized.

[0180] Example 15

[0181] In this Example 15, the all-silicon ITH molecular sieve obtained in Example 1 was added as a seed crystal to prepare a Ti-ITH molecular sieve with a silicon-titanium ratio of 100, comprising the following steps:

[0182] 1) Mixing white carbon black, tetrabutyl titanate, N,N,N,N'-tetramethyl-N',N'-diethyl-1,6-hexanediammonium hydroxide (Method 1) and ammonium fluoride as the silicon source, titanium source, template, and fluorine source, respectively, and stirring at room temperature to evaporate water to a predetermined ratio to obtain a gel mixture. The molar ratios of the silicon source, titanium source, template, water, and ammonium fluoride are as follows:

[0183] SiO2:TiO2:R:H2O:NH4F=1.0:0.005:0.25:5:0.5.

[0184] 2) Transfer the mixture to a reactor and crystallize at 160° C. for 72 h. After the crystallization is completed, cool the crystallized product, filter, wash, dry at 100° C., and calcine at 550° C. to obtain a Ti-ITH molecular sieve.

[0185] Example 16

[0186] In this Example 16, the all-silicon ITH molecular sieve obtained in Example 1 was added as a seed crystal to prepare a Ti-ITH molecular sieve with a silicon-titanium ratio of 50, comprising the following steps:

[0187] 1) Tetraethyl silicate, tetrabutyl titanate, N,N,N,N'-tetramethyl-N',N'-diethyl-1,6-hexanediammonium hydroxide (Method 1) and hydrofluoric acid are mixed as the silicon source, titanium source, template, and fluorine source, respectively, and stirred at room temperature to evaporate water to a predetermined ratio to obtain a gel mixture. The molar ratios of the silicon source, titanium source, template, water, and ammonium fluoride are as follows:

[0188] SiO2:TiO2:R:H2O:HF=1.0:0.01:0.25:10:1.

[0189] The mixture was transferred to a reactor and crystallized at 175° C. for 48 h. After the crystallization, the crystallized product was cooled, filtered, washed, dried at 120° C., and calcined at 600° C. to obtain a Ti-ITH molecular sieve.

[0190] Comparative Example 1

[0191] In this comparative example 1, the preparation of all-silicon ITH molecular sieve includes the following steps:

[0192] 1) Tetraethyl silicate, N,N,N,N'-tetramethyl-N',N'-diethyl-1,6-hexanediammonium hydroxide (Method 1), and hydrofluoric acid are mixed as the silicon source, template, and fluorine source, respectively, and stirred at room temperature to evaporate water to a predetermined ratio to obtain a gel mixture. The molar ratios of the silicon source, template, water, and ammonium fluoride are as follows:

[0193] SiO2:R:H2O:HF=1.0:0.25:10:1.

[0194] 2) Transfer the product to a reactor and crystallize it at 100° C. for 48 h. After the crystallization is completed, cool the crystallized product, filter, wash, and dry it at 120° C. The product is amorphous.

[0195] In combination with Examples 1-16, it can be seen that the method of the present invention uses a template molecule different from the previous work, which can realize the one-step synthesis of all-silicon ITH molecular sieves, silicon-aluminum ITH molecular sieves (i.e., Al-ITH molecular sieves), silicon-boron ITH molecular sieves (i.e., B-ITH molecular sieves), silicon-gallium ITH molecular sieves (i.e., Ga-ITH molecular sieves), and titanium-silicon ITH molecular sieves (i.e., Ti-ITH molecular sieves), without the introduction of expensive germanium species. The silicon-aluminum ratio, silicon-gallium ratio, and silicon-titanium ratio of the all-silicon or heteroatom ITH molecular sieve prepared by the method of the present invention are not less than 50, and the silicon-boron ratio is not less than 30. The adjustable aluminum, boron, gallium, and titanium content make the number of acidic sites and redox active centers in the all-silicon or heteroatom ITH molecular sieves controllable, thereby realizing the function of customizing the molecular sieve to meet the needs of different reaction processes and having a broader application space. In addition, the all-silicon or heteroatom ITH molecular sieve prepared by the method of the present invention has excellent catalytic activity and caprolactam selectivity in the Beckmann rearrangement reaction.

[0196] It can be seen from Comparative Example 1 that, in the process of preparing the all-silicon ITH molecular sieve, if the crystallization temperature is too low (100° C.), amorphous powder will be produced, resulting in the failure to form the molecular sieve.

[0197] In summary, the present invention effectively overcomes the various shortcomings of the prior art and has high industrial utilization value.

[0198] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Anyone skilled in the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by one of ordinary skill in the art without departing from the spirit and technical principles disclosed herein are intended to be covered by the claims of the present invention.

Claims

1. A template, characterized in that The template is N,N,N,N'-tetramethyl-N',N'-diethyl-1,6-hexanediammonium hydroxide, and its structural formula is 。 2. A method for synthesizing an all-silicon or heteroatom ITH molecular sieve, characterized in that: The steps include: 1) mixing a silicon source, a template, water and a fluorine source to obtain a gel mixture; or mixing a silicon source, a heteroatom source, a template, water and a fluorine source to obtain a gel mixture; 2) crystallizing the gel mixture obtained in step 1) to obtain an all-silicon or heteroatom ITH molecular sieve; Wherein, the template agent in step 1) is the template agent as claimed in claim 1.

3. The method for synthesizing the all-silicon or heteroatom ITH molecular sieve according to claim 2, wherein: Also includes any one or more of the following features: A1) the silicon source in step 1) is selected from one or more of white carbon black, silica sol, tetramethyl orthosilicate, tetraethyl orthosilicate and silica gel; A2) the heteroatom source in step 1) is selected from one or more of an aluminum source, a boron source, a gallium source, or a titanium source; A3) the fluorine source in step 1) is selected from hydrofluoric acid and / or ammonium fluoride; A4) the molar ratio of the silicon source, template, water and fluorine source in step 1) is 1:0.25:(1-10):(0.5-1); A5) the molar ratio of the silicon source, heteroatom source, template, water and fluorine source in step 1) is 1:(0-0.017):0.25:(1-10):(0.5-1); A6) Step 2) The crystallization is carried out in a reaction vessel, wherein a seed crystal is provided in the reaction vessel; A7) Step 2) The crystallization temperature is 160-200° C. and the crystallization time is 24-168 h; A8) After the crystallization in step 2) is completed, post-treatment is performed to obtain an all-silicon or heteroatom ITH molecular sieve.

4. The method for synthesizing the all-silicon or heteroatom ITH molecular sieve according to claim 3, wherein: Also includes any one or more of the following features: A21) the aluminum source is selected from one or more of boehmite, aluminum hydroxide, aluminum sulfate 18hydrate, and aluminum isopropoxide; A22) the boron source is boric acid; A23) the gallium source is selected from one or more of gallium nitrate, gallium chloride, and gallium oxide; A24) the titanium source is tetrabutyl titanate; A51) The molar ratio of the silicon source, heteroatom source, template, water and fluorine source is 1:(0.0025-0.017):0.25:(1-10):(0.5-1); A61) the seed crystal is ITH molecular sieve; A62) The mass of the seed crystal accounts for 1% to 30% of the mass of the silicon source in step 1) converted to SiO2 mass; A81) The post-treatment includes washing, drying and calcining.

5. The method for synthesizing the all-silicon or heteroatom ITH molecular sieve according to claim 4, wherein: The drying temperature is 80-120°C.

6. The method for synthesizing the all-silicon or heteroatom ITH molecular sieve according to claim 4, wherein: The calcination temperature is 550-600°C.

7. An all-silicon or heteroatom ITH molecular sieve obtained by the synthesis method according to any one of claims 2 to 6.

8. The all-silicon or heteroatom ITH molecular sieve according to claim 7, characterized in that Also includes any one or more of the following features: B1) when the heteroatom source is an aluminum source, the silicon-to-aluminum ratio of the all-silicon or heteroatom ITH molecular sieve is ≥50; B2) when the heteroatom source is a boron source, the silicon-boron ratio of the all-silicon or heteroatom ITH molecular sieve is ≥30; B3) when the heteroatom source is a gallium source, the silicon-gallium ratio of the all-silicon or heteroatom ITH molecular sieve is ≥50; B4) when the heteroatom source is a titanium source, the silicon-titanium ratio of the all-silicon or heteroatom ITH molecular sieve is ≥50; B5) The all-silicon or heteroatom ITH molecular sieve is a large-sized crystal with a size of (7-35)×(1-4)×(0.1-1) μm.

9. Use of the all-silicon or heteroatom ITH molecular sieve as claimed in claim 7 or 8 as a catalyst in a chemical reaction.

10. The use according to claim 9, characterized in that The chemical reaction includes Beckmann rearrangement, methanol to olefins or catalytic cracking of 1-hexene.

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