Synthesis method and application of all-silicon or heteroatom ITH molecular sieve

Abstract

The invention belongs to the technical field of molecular sieves, and particularly relates to a synthesis method and application of an all-silicon or heteroatom ITH molecular sieve. The synthesis method of the all-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; and 2) crystallizing the gel mixture obtained in the step 1) to obtain the all-silicon or heteroatom ITH molecular sieve. The template agent provided by the invention can be used for synthesizing all-silicon, silicon-aluminum, silicon-boron, silicon-gallium and titanium-silicon ITH molecular sieves in one step, and expensive germanium species do not need to be introduced. In addition, the all-silicon or heteroatom ITH molecular sieve prepared by the method has excellent catalytic activity and caprolactam selectivity in the Beckmann rearrangement reaction.

Description

Technical Field

[0001] The 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, the research group of Professor Avelino Corma of the Polytechnic University of Valencia, Spain, reported a new all-silicon molecular sieve ITQ-13 with a three-dimensional 10*10*9-membered ring structure, with the structural code ITH. Due to the unique 9-membered ring channel, ITH molecular sieve has been proven to have unique performance in reactions such as fluidized catalytic cracking and methanol to olefins, and has attracted widespread attention. However, it is difficult to directly synthesize heteroatom ITH molecular sieves such as silicon and aluminum in one step. Researchers usually use the method of synthesizing silicon-boron ITH molecular sieves first, and then removing boron and supplementing aluminum to obtain aluminum-containing ITH molecular sieves; or in addition to adding heteroatom raw materials, expensive germanium species are also 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 the silicon source and used hexamethonium hydroxide as a template to synthesize an all-silicon ITH molecular sieve (Microporous Mesoporous Mater. 2010, 129, 278–284.); Wu Qinming et al. used hexamethonium bromide as a template to synthesize an all-silicon 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 template agent hexamethonium for ITH molecular sieves, heteroatoms cannot be introduced into the ITH molecular sieve framework; the polymer template agent has a complex structure, the degree of polymerization is difficult to control, and the reproducibility is poor; the synthesis of the pyrrolidino template agent 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 simple template molecule to realize 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 shortcomings of the prior art described above, the purpose of the present invention is to provide a synthesis method and use of an all-silicon or heteroatom ITH molecular sieve, so as to solve the problems in the prior art that traditional templates cannot introduce heteroatoms in the preparation of all-silicon or heteroatom ITH molecular sieves, the polymer templates have complex structures, and pyrrolidino templates must introduce germanium species, resulting in decreased hydrothermal stability of the molecular sieve, decreased crystallinity, and even structural collapse.

[0006] 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

[0007] The second aspect of the present invention provides a method for synthesizing an all-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 an all-silicon or heteroatom ITH molecular sieve.

[0010] In some embodiments of the present invention, 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.

[0011] In some embodiments of the present invention, 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 invention, the fluorine source in step 1) is selected from hydrofluoric acid and / or ammonium fluoride.

[0013] In some embodiments 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).

[0014] In some embodiments of the present invention, 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). Preferably, 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).

[0015] In some embodiments of the present invention, the aluminum source is selected from one or more of boehmite, aluminum hydroxide, aluminum sulfate 18hydrate and aluminum isopropoxide.

[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.; 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; 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-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 present invention also provides the use of all-silicon or heteroatom ITH molecular sieve as a catalyst in a chemical reaction.

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

[0032] The present invention has the following beneficial effects:

[0033] 1) The present invention adopts N,N,N,N'-tetramethyl-N',N'-diethyl-1,6-hexanediammonium hydroxide as a template. Compared with the classic template of all-silicon or heteroatom ITH molecular sieve hexamethylammonium hydroxide, the template of the present application can synthesize all-silicon, silicon-aluminum, silicon-boron, silicon-gallium, titanium-silicon all-silicon or heteroatom ITH molecular sieve in one step without introducing expensive germanium species.

[0034] 2) The all-silicon or heteroatom ITH molecular sieve prepared by the method of the present invention has a larger adjustable range of silicon-aluminum ratio, silicon-boron ratio, silicon-gallium ratio, and silicon-titanium ratio. 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 adjustable aluminum, boron, gallium, and titanium contents make the number of acid sites and redox active centers in the all-silicon or heteroatom ITH molecular sieve controllable, thereby realizing the function of customized molecular sieves to meet the needs of different reaction processes and having a broader application space.

[0035] 3) 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. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 Shown is the liquid H NMR spectrum of the template in Example 1 of the present invention.

[0037] Figure 2 Shown is the liquid C NMR spectrum of the template in Example 1 of the present invention.

[0038] Figure 3 Shown is the XRD spectrum of the all-silicon or heteroatom ITH molecular sieve obtained in Example 1 of the present invention.

[0039] Figure 4 Shown are SEM photographs of the all-silicon or heteroatom ITH molecular sieve obtained in Example 1 of the present invention.

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

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

[0042] Figure 7 Shown is the solid aluminum nuclear magnetic resonance spectrum of the silicon-aluminum all-silicon or heteroatom ITH molecular sieve obtained in Example 4 of the present invention.

[0043] Figure 8 Shown is the XRD spectrum of the silicon-boron all-silicon or heteroatom ITH molecular sieve obtained in Example 7 of the present invention.

[0044] Fig. 9 Shown is the XRD spectrum of the silicon-gallium all-silicon or heteroatom ITH molecular sieve obtained in Example 11 of the present invention.

[0045] Fig.10 Shown is the XRD spectrum of the titanium silicon all-silicon or heteroatom ITH molecular sieve obtained in Example 14 of the present invention.

[0046] Fig.11 Shown is the Beckmann rearrangement reaction activity diagram of the all-silicon or heteroatom ITH molecular sieve in Example 1 of the present invention. DETAILED DESCRIPTION

[0047] Hereinafter, embodiments of the specifically disclosed all-silicon or heteroatom ITH molecular sieves and their synthesis methods and uses are described in detail.

[0048] Before further describing the specific embodiments of the present invention, it should be understood that the scope of protection of the present invention is not limited to the specific embodiments described below; it should also be understood that the terms used in the examples of the present invention are intended to describe specific embodiments, rather than to limit the scope of protection of the present invention. The test methods in the following examples without specifying specific conditions are generally carried out under conventional conditions or under conditions recommended by the manufacturers.

[0049] When the embodiments give numerical ranges, it should be understood that, unless otherwise specified in the present invention, both endpoints of each numerical range and any numerical value between the two endpoints can be selected. Unless otherwise defined, all technical and scientific terms used in the present invention have the same meaning as those generally understood by those skilled in the art. In addition to the specific methods, equipment, and materials used in the embodiments, according to the grasp of the prior art by those skilled in the art and the record of the present invention, any methods, equipment, and materials of the prior art similar or equivalent to the methods, equipment, and materials described in the embodiments of the present invention can also be used to realize the present invention.

[0050] ITH molecular sieve (also known as ITH structure molecular sieve) is a crystalline microporous material, composed of four tetrahedrons (such as silicon, aluminum, phosphorus, etc.) with uniform micropores and molecular-sized cavities. Its unique pore structure can not only effectively regulate acid sites and redox active centers, but also greatly improve reaction activity and selectivity. It is widely used in petrochemical, environmental protection treatment and polymer material synthesis.

[0051] The inventors of the present application have found through long-term experimental research that by using a small molecule organic ammonium template, such as N,N,N,N'-tetramethyl-N',N'-diethyl-1,6-hexanediammonium hydroxide, a one-step crystallization method can be used to obtain all-silicon, silicon-aluminum ratio, silicon-boron ratio, silicon-gallium ratio, silicon-titanium ratio adjustable all-silicon or heteroatom ITH molecular sieves. However, the traditional hexamethylammonium template 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 obtained all-silicon or heteroatom ITH molecular sieve 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 by a German Bruker D2Advance X-ray diffractometer to characterize the crystal structure of the molecular sieve; the SEM image is obtained by a JEOL7800Prime field emission scanning electron microscope of Japan Electron to characterize the morphology of the molecular sieve.

[0053] In a specific embodiment of the present invention, when observed using a scanning electron microscope (SEM), the molecular sieve (referring to a single crystal) has a native crystal morphology of nanosheets or nanoparticles. Wherein, the crystal morphology refers to the external shape presented by a single molecular sieve crystal in the observation field of the scanning electron microscope. The native refers to the structure that the molecular sieve objectively presents directly after preparation, and is not the structure presented by the molecular sieve after artificial processing 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 preparation method of 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 and reflux, stir overnight, and 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;

[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 suction 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 for condensation and reflux, stir overnight, and after the reaction, wash the product with a sufficient amount of ether and dry it in vacuum 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 suction 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 an all-silicon or heteroatom ITH molecular sieve, 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: a silicon source, a template, water and a fluorine source are mixed, or a silicon source, a heteroatom source, a template, water and a fluorine source are stirred at room temperature to volatilize water to a desired amount of water to obtain a gel mixture.

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

[0067] In step 1) of the present invention, the heteroatom source is selected from one or more of an aluminum source, a boron source, a gallium source or a titanium source. In a specific embodiment of the present invention, the aluminum source is selected from one or more of boehmite, aluminum hydroxide, aluminum sulfate 18hydrate 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 invention, 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 element 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 element (tetramethyl orthosilicate will form SiO2 after 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 element is the molar number of Al2O3, B2O3, Ga2O3 obtained by converting the mass of 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 described 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, 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, and after the crystallization is completed, it is washed, dried, and calcined to obtain an all-silicon or heteroatom ITH molecular sieve.

[0071] In step 2) of the present invention, a seed is provided in the reactor, and the seed is an ITH molecular sieve. The ITH molecular sieve seed can be, for example, a completely crystallized ITH molecular sieve containing a template or an ITH molecular sieve from which the template has been removed by high-temperature calcination. The ITH molecular sieve seed 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 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 in 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 crystallization time is 24-168h, which can be 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 crystallization time of the present invention is controlled under this range is that the crystallization time is too long, which will cause the all-silicon or heteroatom ITH molecular sieve to be transformed into a dense phase without a pore structure, causing the molecular sieve to lose screening and catalytic ability; the crystallization time is too short (such as 12h), and the all-silicon or heteroatom ITH molecular sieve may not be fully formed, which will cause the product to be mixed with amorphous substances. This amorphous substance lacks an ordered pore structure and cannot provide ideal catalytic and separation performance.

[0075] In step 2) of the present invention, the washing, drying and roasting are conventional technical means in the art. The drying temperature is 80-120°C, and can be 80-100°C or 100-120°C, preferably 80°C, 100°C or 120°C. The roasting temperature is 550-600°C, and 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 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, and 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 to be 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] In the all-silicon or heteroatom ITH molecular sieve provided by the present invention, the all-silicon or heteroatom ITH molecular sieve is a large-sized 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 (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 7×2×0.48μm or 17×1.63×0.48μm.

[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 flake or block-shaped; 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 the prior art, different chemical reactions have different requirements for catalysts. By regulating the acid sites, the acid strength and density of the molecular sieve can be adjusted to adapt to different acid-catalyzed reactions; and by regulating the redox active centers, the activity and selectivity of the molecular sieve in oxidation and reduction reactions can be optimized to improve the catalytic efficiency. The adjustable aluminum, boron, gallium, and titanium contents of the present invention make the number of acid 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.

[0084] The present invention also provides the use of all-silicon or heteroatom ITH molecular sieve as a catalyst in a chemical reaction. The chemical reaction may be, for example, Beckmann rearrangement, methanol to olefins or 1-hexene catalytic cracking.

[0085] The Beckmann rearrangement described in the present invention is an organic rearrangement reaction in which ketoxime is converted into amide under the action of acid. The all-silicon or heteroatom ITH molecular sieve of the present invention can provide a suitable acidic environment for the Beckmann rearrangement reaction by virtue of its weaker acidic sites, promote the formation and stabilization of reaction intermediates, and thus improve the yield and selectivity.

[0086] The methanol-to-olefins process described in the present invention is to convert methanol into low-carbon 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 generation of by-products.

[0087] The 1-hexene catalytic cracking of the present invention refers to the process of converting 1-hexene into smaller olefins or other organic products through a catalytic cracking reaction. In this process, the pore structure and redox active center of the all-silicon or heteroatom ITH molecular sieve of the present invention contribute to an effective cracking reaction, generate smaller olefins, and exhibit 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 in conjunction with embodiments and drawings.

[0089] In the following examples, unless otherwise specified, 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 is prepared by method 1:

[0093] (1) Dissolve 1-bromo-6-(trimethylammonium)hexyl bromide and N,N-diethylmethylamine 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, and after the reaction, wash the product with sufficient ether and dry it under vacuum 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 suction filtration, and rotary evaporate to obtain a 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 embodiment 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 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 ratio of silicon source, template, water and hydrogen fluoride is as follows:

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

[0101] 2) Transfer to a reactor and crystallize at 160° C. for 168 h. After the crystallization is completed, cool, filter, wash, dry at 80° C., and calcine 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] The above characterization results demonstrate that the method of the present application can be used to 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 device 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 N2 (80 ml / min) atmosphere at 400°C at normal pressure for 30 min, anhydrous ethanol was introduced at a flow rate of 0.1 ml / min for 30 min for activation, and then switched to a 35 wt.% cyclohexanone oxime ethanol solution for reaction. During the reaction, the pressure was normal pressure, the temperature was maintained at 380°C, and the mass space velocity was 6 h -1 Samples were taken every 1 h, and the products were analyzed by Agilent GC 8090 gas chromatograph equipped with a FID detector and a 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) Mix white carbon black, 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, and stir at room temperature to evaporate water to a predetermined ratio to obtain a gel mixture.

[0112] Wherein, the molar ratio of silicon source, template, water and ammonium fluoride is as follows:

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

[0114] 2) Transfer to a reactor and crystallize at 160° C. for 72 h. After the crystallization is completed, cool, 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) 40wt.% silica sol, N,N,N,N'-tetramethyl-N',N'-diethyl-1,6-hexanediammonium hydroxide (method 1) and hydrofluoric acid are mixed as 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 ratio of silicon source, template, water and ammonium fluoride is as follows:

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

[0119] 2) Transfer to a reactor and crystallize at 175° C. for 48 hours. After the crystallization is completed, cool, 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 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 ratio of silicon source, aluminum source, template, water and hydrogen fluoride is as follows:

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

[0124] 2) Transfer to a reactor and crystallize at 160° C. for 168 h. After the crystallization is completed, cool, 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 nuclear magnetic resonance (NMR). Figure 8 , proving 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 is 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) Mix white carbon black, aluminum sulfate 18hydrate, N,N,N,N'-tetramethyl-N',N'-diethyl-1,6-hexanediammonium hydroxide (method 1) and ammonium fluoride as silicon source, aluminum source, template and fluorine source respectively, and stir at room temperature to evaporate water to a predetermined ratio to obtain a gel mixture. The molar ratio of silicon source, aluminum source, template, water and ammonium fluoride is as follows:

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

[0131] 2) Transfer to a reactor and crystallize at 160° C. for 72 h. After the crystallization is completed, cool, 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 is added as a seed crystal to prepare an Al-ITH molecular sieve with a silicon-aluminum ratio of 50, comprising the following steps:

[0134] 1) Tetraethyl silicate, boehmite, N,N,N,N'-tetramethyl-N',N'-diethyl-1,6-hexanediammonium hydroxide (method 1) and hydrofluoric acid are mixed as 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 ratio of silicon source, aluminum source, template, water and ammonium fluoride is as follows:

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

[0136] 2) Transfer to a reactor and crystallize at 175° C. for 48 h. After the crystallization is completed, cool, 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,N'-tetramethyl-N',N'-diethyl-1,6-hexanediammonium hydroxide (method 1) and hydrofluoric acid are mixed as 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 ratio of silicon source, boron source, template, water and hydrogen fluoride is as follows:

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

[0141] 2) Transfer to a reactor and crystallize at 160° C. for 168 h. After the crystallization is completed, cool, 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. Fig. 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) 30.5wt.% white carbon black, boric acid, N,N,N'-tetramethyl-N',N'-diethyl-1,6-hexanediammonium hydroxide (method 1) and ammonium fluoride are mixed as 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 ratio of silicon source, boron source, template, 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 reactor and crystallize at 160° C. for 72 h. After the crystallization is completed, cool, filter, wash, dry at 100° C., and calcine at 550° C. to obtain a B-ITH molecular sieve.

[0148] Example 9

[0149] In this Example 9, the all-silicon ITH 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 50, including the following steps:

[0150] 1) Tetraethyl silicate, boric acid, N,N,N,N'-tetramethyl-N',N'-diethyl-1,6-hexanediammonium hydroxide (method 1) and hydrofluoric acid are mixed as 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 ratio of silicon source, aluminum source, template, 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 reactor and crystallize at 175° C. for 48 h. After the crystallization is completed, cool, filter, wash, dry at 120° C., and calcine at 600° C. to obtain a B-ITH molecular sieve.

[0153] Example 10

[0154] In this Example 10, the all-silicon ITH 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 30, including the following steps:

[0155] 1) Tetraethyl silicate, boric acid, N,N,N,N'-tetramethyl-N',N'-diethyl-1,6-hexanediammonium hydroxide (method 1) and hydrofluoric acid are mixed as 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 ratio of silicon source, aluminum source, template, 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 a reaction kettle and crystallize at 175° C. for 24 h. After the crystallization is completed, cool, filter, wash, dry at 100° C., and calcine at 600° C. to obtain a B-ITH molecular sieve.

[0158] Embodiment 11

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

[0160] 1) 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 and fluorine source respectively, and stirred at room temperature to evaporate water to a predetermined ratio to obtain a gel mixture. The molar ratio of silicon source, gallium source, template, 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 a reactor and crystallize at 160° C. for 168 h. After the crystallization is completed, cool, filter, wash, dry at 80° C., and calcine at 550° C. to obtain Ga-ITH molecular sieve.

[0163] The obtained Ga-ITH molecular sieve was characterized by XRD. Fig.10 , proving that highly crystalline Ga-ITH molecular sieves can be synthesized.

[0164] Example 12

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

[0166] 1) Mix white carbon black, gallium oxide, N,N,N,N'-tetramethyl-N',N'-diethyl-1,6-hexanediammonium hydroxide (method 1) and ammonium fluoride as silicon source, gallium source, template and fluorine source respectively, and stir at room temperature to evaporate water to a predetermined ratio to obtain a gel mixture. The molar ratio of silicon source, gallium source, template, 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 to a reactor and crystallize at 160° C. for 72 h. After the crystallization is completed, cool, 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 is 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 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 ratio of silicon source, gallium source, template, water and ammonium fluoride is 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] Embodiment 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 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 ratio of silicon source, titanium source, template, water and hydrogen fluoride is as follows:

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

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

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

[0180] Embodiment 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) Mix white carbon black, tetrabutyl titanate, N,N,N,N'-tetramethyl-N',N'-diethyl-1,6-hexanediammonium hydroxide (method 1) and ammonium fluoride as silicon source, titanium source, template and fluorine source respectively, and stir at room temperature to evaporate water to a predetermined ratio to obtain a gel mixture. The molar ratio of silicon source, titanium source, template, water and ammonium fluoride is as follows:

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

[0184] 2) Transfer to a reactor and crystallize at 160° C. for 72 h. After the crystallization is completed, cool, 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, including 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 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 ratio of silicon source, titanium source, template, water and ammonium fluoride is 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 hours. 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 comprises 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 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 ratio of silicon source, template, water and ammonium fluoride is as follows:

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

[0194] 2) Transfer to a reaction kettle and crystallize at 100° C. for 48 h. After the crystallization is completed, cool, filter, wash and dry the crystallized product 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), and there is no need to introduce 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 acid sites and redox active centers in the all-silicon or heteroatom ITH molecular sieves controllable, thereby realizing the function of customizing molecular sieves to meet the needs of different reaction processes and have a broader application space. In addition, the all-silicon or heteroatom ITH molecular sieves prepared by the method of the present invention have 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 a molecular sieve.

[0197] In summary, the present invention effectively overcomes 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 familiar with 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 a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A template, characterized in that The template agent 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, characterized in that: 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; the crystallization time is 24-168h; 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, characterized in that: 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 into 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, characterized in that: The drying temperature is 80-120°C.

6. The method for synthesizing the all-silicon or heteroatom ITH molecular sieve according to claim 4, characterized in that: 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 gallium 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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