Cubic nano EU-1 molecular sieve as well as synthesis method and application thereof

Abstract

The invention discloses an EU-1 molecular sieve and a synthesis method thereof, and belongs to the field of EU-1 molecular sieves. According to the EU-1 molecular sieve disclosed by the invention, the EU-1 molecular sieve is in a tetragonal shape; the average grain size of grains of the EU-1 molecular sieve is less than or equal to 600nm, the specific surface area SBET of the EU-1 molecular sieve is more than or equal to 390m < 2 > / g, and the micropore volume Vmicro is more than or equal to 0.22 cm < 3 > / g; the synthesis method of the EU-1 molecular sieve comprises the following steps: mixing a template agent, a silicon source, an aluminum source, an alkali source and a solvent I, aging, and carrying out segmented crystallization to obtain the EU-1 molecular sieve, according to the synthesis method of the EU-1 molecular sieve, disclosed by the invention, the EU-1 molecular sieve can be induced to form nucleated microcrystals to modulate within a very wide range by controlling crystallization time and temperature, so that a nanoscale product, namely the EU-1 molecular sieve, is obtained; in addition, the EU-1 molecular sieve crystal grain morphology can have a specific square morphology by regulating and controlling the proportion of cations in the crystallization system.

Description

Technical Field

[0001] The invention relates to the field of EU-1 molecular sieve synthesis, and in particular to a cubic nano EU-1 molecular sieve and a synthesis method and application thereof. Background Art

[0002] The EU-1 molecular sieve, which belongs to the EUO topological structure, is a novel medium-pore high-silicon molecular sieve with a one-dimensional microporous channel structure (the space group belongs to Cmma) and a regular porous silicon-aluminum composition material. This structural molecular sieve was first disclosed by Casci et al. in their European patent EP42226 and USP4537754 in 1981. The EU-1 molecular sieve framework contains a 10MR (ten-membered ring) straight microporous channel and a 12MR (twelve-membered ring) side pocket structure vertically connected to it; wherein, the side pocket depth is 0.81nm, and the side pocket opening diameter is 0.68nm×0.58nm, which is interconnected with the outer surface of the crystal through the 10MR microporous channel, and the 10MR channel has an elliptical opening and the opening diameter is 0.41nm×0.58nm. The one-dimensional 10MR channel of EU-1 molecular sieve and its side deep holes can form a special shape-selective effect, which is easy to cause bimolecular reactions such as xylene disproportionation (Zeolites, 1988, 8 (7): 74-76.). Due to the particularity of its pore structure, EU-1 molecular sieve has been widely studied in the field of petrochemical industry, specifically in the reactions of xylene isomerization (US Patent USP20010051757), reducing the pour point of waxy oil products (US Patent USP20030127356), and benzene isopropylation. It has excellent shape-selective catalytic performance and has good commercial value and application prospects. The French National Petroleum Institute (IFP) has been studying the preparation of EUO structure molecular sieves since the 1990s and applied them as acidic components in xylene isomerization catalysts. Under the same conditions, it has higher activity and selectivity than conventional molecular sieve catalysts.

[0003] So far, the synthesis routes of EU-1 molecular sieves with EUO topology can be basically divided into two categories: hydrothermal method based on liquid phase transformation mechanism and dry gel method based on solid phase transformation mechanism. These methods usually require a large amount of templates (the molar ratio of template to system silicon oxide is greater than 0.2) in the synthesis system, which is expensive and environmentally unfriendly (templates are highly toxic and produce high concentrations of halogens, etc.), which seriously limits the efficient production of nano EU-1 molecular sieves. It is urgent to reduce the use and dependence on such organic templates through technical improvements. EU patent EP159845 discloses a method for synthesizing EUO structured molecular sieves using dimethylbenzene (DBDMA) as a template. U.S. Patent US2001 / 0051757A1 discloses a method for synthesizing a low silicon-aluminum ratio EUO structure molecular sieve, which uses diphenylmethyl dimethylamine or its precursor as a structure directing agent and adds at least one seed including an EUO type molecular sieve to the synthesis system. A reaction mixture formed by uniformly mixing a silicon source, an aluminum source, an alkali metal compound, a template agent and the seed is hydrothermally crystallized to obtain a EU-1 molecular sieve with a Si / Al molar ratio of 5 to 50.

[0004] The preparation method of the above-mentioned EU-1 molecular sieve, which is synthesized by HMBr2 template-guided EU-1 molecular sieve, is carried out in a liquid hydrothermal system, follows the liquid phase crystallization mechanism, has a long crystallization time, and requires a large amount of template. Its morphology is usually shuttle-shaped crystals, and most of the molecular sieves obtained are larger particles with a particle size of microns. The preparation cost is high, the environment is polluted, and it is not suitable for large-scale industrial production and use. Summary of the invention

[0005] In order to overcome the technical problems of large product particle size and difficult to control crystal morphology during the synthesis of EU-1 molecular sieve, the present invention provides a cubic nano EU-1 molecular sieve and its synthesis method and application. The obtained EU-1 molecular sieve has the advantages of nanometer particle size and uniform cubic morphology.

[0006] In order to solve the above technical problems, the first aspect of the present invention provides a EU-1 molecular sieve, wherein the crystal form of the EU-1 molecular sieve is tetragonal; the average crystal size of the EU-1 molecular sieve is ≤600nm, and the specific surface area S of the EU-1 molecular sieve is BET 390m 2 / g~700m 2 / g, micropore volume V micro 0.22cm 3 / g~0.60cm 3 / g.

[0007] According to some embodiments of the present invention, the average crystal size of the EU-1 molecular sieve is 2 nm to 200 nm.

[0008] According to some embodiments of the present invention, the silicon-aluminum molar ratio of the EU-1 molecular sieve is 5-500, preferably 25-170.

[0009] According to some embodiments of the present invention, the EU-1 molecular sieve contains eight regular vertices. Preferably, the EU-1 molecular sieve is in the shape of a cuboid or a cube.

[0010] According to some embodiments of the present invention, the specific surface area S of the EU-1 molecular sieve is BET 420m 2 / g~514m 2 / g, micropore volume V micro 0.28cm 3 / g~0.44cm 3 / g.

[0011] The second aspect of the present invention provides a method for synthesizing the above-mentioned EU-1 molecular sieve, comprising the steps of mixing a template, a silicon source, an aluminum source, an alkali source and a solvent I, aging and crystallizing to obtain the EU-1 molecular sieve.

[0012] According to some embodiments of the present invention, the silicon source is selected from at least one of silica sol, water glass, kaolin and white carbon black or selected from active silicon powder;

[0013] In the ultraviolet Raman spectrum of the active silicon powder, at the vibration frequency of 240cm -1 There are characteristic peaks nearby, with a vibration frequency no greater than 600cm -1 In the characteristic area, there is at least one non-240cm -1 Characteristic peaks near 240cm -1 The sum of the peak areas of the nearby characteristic peaks is no more than 600 cm -1 The total area of ​​the characteristic peaks in the characteristic region is ≥ 20% but not more than 98% (correspondingly, at 240 cm -1 The area of ​​the characteristic peaks near the -1 The total area of ​​characteristic peaks in the characteristic region is ≤80%).

[0014] In some embodiments of the present invention, in the ultraviolet Raman spectrum of the active silicon powder, at a vibration frequency of no more than 600 cm -1 In the characteristic region, there is a vibration frequency of 335cm -1 、400cm -1 and 480cm -1 At least one characteristic peak in the vicinity.

[0015] In the present invention, the peak area of ​​each characteristic peak can be obtained by automatic (or manual if necessary) integration in a spectrometer. The present invention does not limit the specific peak area of ​​each characteristic peak. -1 The peak area of ​​the characteristic peaks near 240 cm -1 The relationship between the areas of nearby characteristic peaks has corresponding limitations.

[0016] The active silicon powder of the present invention is silicon powder containing structural units. In the present invention, the structural unit in the "active silicon powder" refers to a silicon-containing four-membered ring (4MR), five-membered ring (5MR) or six-membered ring (6MR) that can constitute the molecular sieve skeleton structure.

[0017] According to the present invention, 240cm -1 The characteristic peak near is the characteristic signal of TOT bending vibration of silicon-containing eight-membered ring (8MR). When the ultraviolet Raman spectrum of the active silicon powder is at 240cm -1 When there is a characteristic peak nearby, it means that the silicon atoms in the active silicon powder have overcome the skeleton stress and formed more of the aforementioned 4MR, 5MR or 6MR active structural units.

[0018] According to the present invention, in the ultraviolet Raman spectrum of the active silicon powder, 240 cm -1 The characteristic peaks near the 8-membered ring (8MR) represent the bending vibration of TOT in the silicon-containing 8-membered ring; the vibration frequency is not more than 600 cm -1 In the characteristic region, the smaller rings correspond to higher vibration frequencies, not 240 cm -1 Among the characteristic peaks nearby, 335cm -1 、400cm -1 or 480cm -1 The characteristic peaks near 240cm represent the bending vibration of TOT in the six-membered ring (6MR), five-membered ring (5MR) and four-membered ring (4MR) containing silicon. -1 The sum of the peak areas of the nearby characteristic peaks is no more than 600 cm -1 The total area of ​​the characteristic peaks in the characteristic region is ≥20%, indicating that the silicon atoms in the active silicon powder have more active structural units such as four-membered rings (4MR), five-membered rings (5MR) or six-membered rings (6MR).

[0019] In some embodiments of the present invention, in the ultraviolet Raman spectrum of the active silicon powder, at a vibration frequency of no more than 600 cm -1 In the characteristic area, non-240cm -1 The characteristic peak near is 335cm -1 、400cm -1 and 4480cm -1 At least one of the nearby characteristic peaks.

[0020] In some embodiments of the present invention, at a vibration frequency of no more than 600 cm -1 In the characteristic area, non-240cm -1 The characteristic peak near 335cm -1 、400cm -1 and 480cm -1 The sum of the peak areas of at least one of the characteristic peaks nearby is no more than 600 cm -1 The total area of ​​characteristic peaks in the characteristic region is ≥50%.

[0021] Regarding the expression “near” in the above content, those skilled in the art will know that since each characteristic peak in the ultraviolet Raman spectrum usually has a displacement, the position of the characteristic peak defined in the present invention may have a deviation, such as 480cm -1 The nearby characteristic peak is at 450cm -1 ~500cm -1 However, the vibration represented by each characteristic peak can be determined by those skilled in the art.

[0022] In the present invention, the above-mentioned “no more than 600cm -1 The characteristic area generally refers to 0cm -1 ~600cm -1 (e.g. 150cm -1 ~600cm -1 ) in the ultraviolet Raman spectrum region. Those skilled in the art will understand that if a characteristic peak appears in an area where the characteristic peak is not easy to appear in the active silicon powder, it should be verified whether it is an impurity peak formed by contamination.

[0023] According to some embodiments of the present invention, the specific surface area of ​​the active silicon powder is 200m 2 / g~980m 2 / g, preferably 550m 2 / g~980m 2 / g.

[0024] According to some embodiments of the present invention, in the active silicon powder, the mass fraction of SiO2 is >90%, preferably >95%, and further preferably >98%.

[0025] According to some embodiments of the present invention, the pore volume of the active silicon powder is 0.2 cm 3 / g~3.0cm 3 / g.

[0026] The method for preparing the active silicon powder comprises the following steps:

[0027] S1, providing a mixed solution I containing a treatment reagent and a solvent II;

[0028] S2, mixing the silicon-containing raw material with the mixed solution I to obtain a mixed solution II;

[0029] S3, performing activation treatment on the mixed solution II to obtain an activated product;

[0030] S4, calcining the activated product to obtain the silicon powder.

[0031] In some embodiments of the present invention, in step S1, the treatment reagent is selected from at least one of an inorganic base, a fluorine-containing substance, an organic base and an ionic liquid containing an organic anion; preferably at least one of ammonia water, sodium hydroxide, potassium hydroxide, sodium carbonate, sodium bicarbonate, hydrofluoric acid, sodium fluoride, ammonium fluoride, silicon tetrafluoride, tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide and 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM]PF6).

[0032] In the present invention, 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM]PF6) is an imidazole-type ionic liquid.

[0033] In the present invention, the treatment reagent is preferably an organic quaternary ammonium base or fluoride, that is, at least one selected from hydrofluoric acid, sodium fluoride, ammonium fluoride, silicon tetrafluoride, tetramethylammonium hydroxide, tetraethylammonium hydroxide and tetrapropylammonium hydroxide.

[0034] In the present invention, when used, the treatment reagent is usually prepared into a solution of a certain concentration using water or alcohol as a solvent. For example, the organic base can be prepared into an aqueous solution or an alcohol solution. Those skilled in the art can make a selection based on actual conditions.

[0035] In some embodiments of the present invention, in step S1, the solvent II is selected from at least one of water, alcohols and ionic liquids; preferably at least one of deionized water, methanol, ethanol, isopropanol, ethylene glycol and 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM]PF6).

[0036] In some embodiments of the present invention, in step S2, the silicon-containing raw material is selected from at least one of diatomaceous earth, water glass, (liquid) silica sol, white carbon black, gas-phase silica sol, silicon powder, silicone resin microspheres, silicates (such as tetramethyl silicate, tetraethyl silicate or tetrapropyl silicate), silicon tetrachloride and silane; wherein the silane is preferably selected from at least one of tetramethylsilane Si(CH3)4, methyltrimethoxysilane MTMS, isobutylene triethoxysilane, trichlorosilane SiHCl3 and tetraethoxysilane Si(OC2H5)4.

[0037] In the present invention, the silicon-containing raw material is preferably liquid silica sol, silicate or silane.

[0038] In the present invention, the optional silicon-containing raw materials mentioned above are all silicon-containing materials commonly used in the art.

[0039] In some embodiments of the present invention, the molar ratio of the treatment reagent to SiO2 in the silicon-containing raw material (hereinafter referred to as the treatment reagent / SiO2 molar ratio) is 0.0001 to 10:1, preferably 0.0001 to 0.1:1.

[0040] In some embodiments of the present invention, the molar ratio of the solvent II to SiO2 in the silicon-containing raw material (hereinafter referred to as the solvent II / SiO2 molar ratio) is 0.5 to 50:1.

[0041] In some embodiments of the present invention, the molar ratio of the total hydroxide anions in the treatment reagent and the solvent II to the SiO2 in the silicon-containing raw material (hereinafter referred to as OH - / SiO2) is 2~60:1.

[0042] In some embodiments of the present invention, in step S2, the conditions for the mixing treatment include: a stirring speed of 0 to 5000 rpm, preferably 0 to 50 rpm; and a temperature of 0 to 50°C, preferably 5 to 30°C.

[0043] In some embodiments of the present invention, in step S3, the process for performing the activation treatment (also referred to as the gelling process) is selected from The method comprises at least one of the following steps: preparing monodisperse SiO2 microspheres by alkaline hydrolysis of tetraethyl orthosilicate (TEOS), hydrolysis, oligomer precipitation, alkaline dissolution and hot melting to highlight the mineralization effect on silicon atoms.

[0044] The activated The process includes mixing and hydrolysis steps; the hydrolysis step of the activation treatment is mainly controlled by controlling the hydrolysis catalyst (promoter or inhibitor) and temperature, stirring / ultrasound / irradiation, time and other parameters; the oligomer precipitation of the activation treatment includes the steps of hydrolysis, solvent network bonding and growth; the alkali dissolution of the activation treatment includes adding a certain amount of ammonia water, sodium hydroxide or potassium hydroxide solution with a certain concentration into the above preparation process; the hot melt of the activation treatment refers to a single-stage or segmented high-temperature heat treatment at 300-1000°C for a certain period of time.

[0045] In the present invention, the activation treatment preferably uses an optimized Specifically, the hydrolysis, bonding and SiO2 growth rates can be controlled by the amount of solvent, temperature and stirring speed to achieve uniformity and controllability of silicon powder.

[0046] According to the present invention, The process, hydrolysis, oligomer precipitation, alkali dissolution and hot melting are all conventional methods of the present invention. The present invention does not strictly limit the various parameters involved in the process, and those skilled in the art can determine them according to actual conditions.

[0047] In some embodiments of the present invention, the conditions for the activation treatment include: a temperature not higher than 200°C (such as 0-200°C), preferably not higher than 100°C (such as 0-100°C); a treatment time of 1 hour to 500 days, preferably 12 hours to 12 days. Further preferably, the activation treatment is completed at a temperature of 0-10°C, a temperature of 10-30°C, a temperature of 30-80°C, and a temperature of 80-100°C (staged constant temperature heat treatment) for 0 to 120 hours (such as 1 to 120 hours).

[0048] In some embodiments of the present invention, after obtaining the activated product of step S3, before the calcination treatment of step S4, the activated product can also be subjected to impurity removal treatment, and water-soluble impurities and solvents, including all impurities such as physically adsorbed water, alcohols, salts and ionic liquids, can be removed by means of forced air drying, vacuuming, etc. At the same time, a maximum of Si, C, H, O, F, S, Br, Cl or MoO can be retained at the same time. x At least one composition.

[0049] In some embodiments of the present invention, in step S4, the conditions for the calcination treatment include: a temperature of 200 to 1000°C, preferably 400 to 600°C; a time of 0.05 to 500 hours; further preferably, within the temperature range of 200 to 1000°C (preferably 400 to 600°C), at least two calcination temperatures are selected from low to high in an air atmosphere and calcined for 0.05 to 2 hours respectively, for example, in an air atmosphere, calcined at 150 to 200°C, 250 to 350°C, 400 to 500°C, and 500 to 600°C in sequence for 0.05 to 2 hours.

[0050] In some embodiments of the present invention, during the calcination treatment, a programmed temperature increase of 0.5 to 5° C. / min is used to raise the temperature from room temperature to the calcination temperature (ie, 150 to 1000° C., preferably 400 to 600° C.).

[0051] In the present invention, the calcination treatment is used to remove the skeleton crystal water (the desorption temperature is usually ≥ 200°C under normal pressure), sublimable fluoride, sulfur or MoO x Impurities such as alkali or salt molecules of the organic template can be completely decomposed by high temperature oxidation.

[0052] According to some embodiments of the present invention, the aluminum source is selected from at least one of aluminum sulfate, sodium aluminate, aluminum chloride, aluminum nitrate and pseudo-boehmite;

[0053] And / or, the alkali source is selected from at least one of tetraethylammonium hydroxide aqueous solution, tetramethylammonium hydroxide methanol solution, ammonia water, sodium hydroxide aqueous solution, potassium hydroxide aqueous solution, and rubidium hydroxide aqueous solution; preferably, the mass concentration of the tetraethylammonium hydroxide aqueous solution is 10% to 40%, the mass concentration of the tetramethylammonium hydroxide methanol solution is 15% to 40%, the mass concentration of the ammonia water is 15% to 40%, the mass concentration of the sodium hydroxide aqueous solution is 10% to 40%, the mass concentration of the potassium hydroxide aqueous solution is 5% to 20%, and the mass concentration of the rubidium hydroxide aqueous solution is 1% to 10%; further preferably, the mass concentration of the tetraethylammonium hydroxide aqueous solution is 25%, the mass concentration of the tetramethylammonium hydroxide methanol solution is 25%, the mass concentration of the ammonia water is 25%, the mass concentration of the sodium hydroxide aqueous solution is 15% to 32%, for example, 15%, 22%, 32%, the mass concentration of the potassium hydroxide aqueous solution is 15%, and the mass concentration of the rubidium hydroxide aqueous solution is 6%;

[0054] And / or, the template agent is selected from at least one of hexamethonium bromide, an aqueous solution or methanol solution of hexamethonium hydroxide, and a template agent precursor; preferably, the template agent precursor is prepared by dissolving a dihalogenated alkane and a monoamine in an organic solvent; preferably, the dihalogenated alkane is 1,6-dibromohexane or 1-chloro-6-bromohexane; preferably, the monoamine is trimethylamine; preferably, the organic solvent is acetone; the molar ratio of the dihalogenated alkane, the monoamine and the organic solvent is: (1-50): (3-100): (5-50), preferably (3-25): (5-60): (10-30); further preferably, the mass concentration of the aqueous solution or methanol solution of hexamethonium hydroxide is 5% to 45%, preferably 25%;

[0055] And / or, the solvent I is at least one of deionized water, ethanol, glycerol, acetone, n-butanol, imidazole-type ionic liquid, and [bmim]PF6 anionic ionic liquid.

[0056] According to some embodiments of the present invention, the template, silicon source, aluminum source, alkali source and solvent I are mixed to obtain an initial gel mixture; preferably, the molar ratio of the template, silicon source, aluminum source, alkali source and solvent I is (1-20): (10-180): 1: (0-60): (50-900), preferably (1-20): (30-180): 1: (0-60): (60-900);

[0057] And / or, the aging is carried out at a temperature of 20°C to 25°C, such as 20°C, 22°C, 25°C, and the aging time is 0h to 4h, preferably 0.5h to 4h, such as 0.5h, 1.5h, 2h, 3h, 3.5h;

[0058] And / or, the crystallization adopts a segmented crystallization process, including pre-crystallization and crystallization; preferably, the pre-crystallization temperature is 30°C to 120°C, preferably 60°C to 120°C, for example, 80°C, 95°C, 100°C, 115°C, 120°C; the pre-crystallization time is 0.5h to 12h, preferably 2h to 10h, for example, 2h, 4h, 5h, 6h, 10h; further preferably, the crystallization temperature is 120°C to 200°C, preferably 150°C to 195°C, for example, 175°C, 180°C, 185°C, 195°C; the crystallization time is 24h to 120h, preferably 24h to 72h, for example, 24h, 42h, 48h, 72h;

[0059] And / or, the crystallization further includes the steps of cooling, filtering, washing and drying.

[0060] According to some embodiments of the present invention, the method for synthesizing the EU-1 molecular sieve comprises the following steps:

[0061] 1) mixing an aluminum source with a portion of solvent I to obtain a solution A having a concentration of 0.5 wt% to 60 wt%, preferably 19.0 wt% to 26.0 wt%;

[0062] 2) mixing the silicon source with another portion of solvent I to obtain a solution B having a concentration of 1 wt% to 95 wt%, preferably 28.0 wt% to 40.0 wt%;

[0063] 3) Add solution B dropwise to solution A under stirring to react and form a gel;

[0064] 4) adding a template to the gel obtained in step 3), stirring for 1 h to 2 h, and adjusting the pH value to 10.5-14, preferably 10.8-13.1, using an alkali source to obtain an initial gel;

[0065] 5) The initial gel obtained in step 4) is transferred into a sealed reaction tank, pre-crystallized under hydrothermal conditions at a temperature of 30°C to 120°C for 0.5h to 12h, and then hydrothermally crystallized at a temperature of 120°C to 200°C for 24h to 120h. The resulting crystallized product is cooled, filtered, washed, and dried to obtain a final solid product, namely the EU-1 molecular sieve.

[0066] According to some embodiments of the present invention, in step 3), the dripping time is 10 min to 12 h, for example, 10 min, 25 min, 50 min, 60 min, 120 min, 240 min.

[0067] It is generally believed that crystal growth must go through the process of nucleation, growth and growth cessation. Under the same crystallization conditions, the more nuclei the crystallization system can provide, the faster the crystallization rate is, and it is easier to generate crystals with smaller particle sizes. The reason why the segmented crystallization strategy has guiding activity is that through the pre-crystallization low-temperature induction process, the crystallization system contains extremely small nuclei with a certain crystal structure, and its existence is the fundamental reason for accelerating the rapid growth of crystals. The pre-crystallization process induced by the lower temperature stage of the present invention already contains the nuclei of EU-1 molecular sieve. Since the nuclei particles are very small, they are very evenly dispersed in the synthetic reaction mixture, so they have a good structural guiding effect.

[0068] Secondly, the cations in the crystallization system include inorganic alkali metal ions and organic quaternary ammonium ions, that is, the molar ratio of the template to the alkali source is critical. In the present invention, the proportion of cations is appropriately controlled in the segmented crystallization stage of the EU-1 molecular sieve to obtain fine EU-1 molecular sieve microcrystals containing a large amount of incomplete crystallization, and then hydrothermally crystallized by the traditional high-temperature method to induce nucleation and increase the crystallization rate. The grain size of the resulting product EU-1 molecular sieve can even be significantly reduced to less than one-tenth of the size of the product synthesized by the conventional method.

[0069] A third aspect of the present invention provides an application of the EU-1 molecular sieve or the EU-1 molecular sieve synthesized by the above method in aromatic ring alkylation and alkyl side chain aromatic isomerization reactions.

[0070] Beneficial effects:

[0071] The synthesis method of the cubic nano EU-1 molecular sieve of the present invention has two obvious advantages. One is that the EU-1 molecular sieve induced nucleation microcrystals can be adjusted in a wide range by controlling the crystallization time and temperature, thereby obtaining a nanoscale product EU-1 molecular sieve; the second is that by regulating the ratio of cations in the crystallization system, that is, the molar ratio of the template agent to the alkali source, the EU-1 molecular sieve grains have a cubic morphology.

[0072] The synthesis method of cubic nano EU-1 molecular sieve of the present invention can solve the problem that the crystal particles are much larger than the crystal nucleus, the dispersion degree in the reaction mixture is smaller than the crystal nucleus with small particle size, and it is difficult to disperse evenly, the structure guiding effect will be significantly weakened, and the synthesis system is easy to generate impure crystals of other structures. BRIEF DESCRIPTION OF THE DRAWINGS

[0073] Figure 1 This is the XRD spectrum of the cubic nano EU-1 molecular sieve prepared in Example 1 of the present invention;

[0074] Figure 2 This is a HR-TEM photo of the cubic nano EU-1 molecular sieve prepared in Example 1 of the present invention;

[0075] Figure 3 This is a TEM photo of the active silicon powder SG1 prepared in Example 1 of the present invention;

[0076] Figure 4 The UV-Raman spectra of the active silicon powder SG1 and white carbon black A200 prepared in Example 1 of the present invention;

[0077] Figure 5 The nitrogen low temperature adsorption-desorption (BET) curves of the active silicon powder SG1 and white carbon black A200 prepared in Example 1 of the present invention;

[0078] Figure 6 FT-IR spectra of the active silicon powder SG1 and white carbon black A200 prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0079] The present invention will be further described below in conjunction with the accompanying drawings and embodiments, but the present invention is not limited to these embodiments.

[0080] The specific surface area S of the EU-1 molecular sieve in the present invention is BET , micropore volume V micro The specific surface area S of the sample was determined by using a Tristar3000 surface area analyzer produced by Micrometrics for low-temperature N2 adsorption-desorption analysis. The sample was pretreated with vacuum activation at 300°C for 6 hours before testing. The test temperature was -196°C. The specific surface area S of the test sample was obtained by analyzing the isotherm. BET , micropore volume V micro And other structural data.

[0081] The phase analysis (XRD test) in the present invention is carried out on a Bruker D8Focus diffractometer, with a graphite monochromator, a Cu target Kα ray light source, a wavelength λ of 0.154 nm, a tube voltage of 40 kV, a tube current of 40 mA, and recording diffraction signals in the 2θ range of 3-90° (scanning speed of 2° / min);

[0082] The high-resolution scanning electron imaging (HR-TEM images) in the present invention was taken using a NovaNanoSEM450 microscope from FEI Company;

[0083] In the present invention, the specific surface area and pore volume of the active silicon powder are analyzed by low-temperature N2 adsorption-desorption analysis of the sample using a Tristar3000 specific surface analyzer produced by Micrometrics. The sample is pretreated at 300°C for 6 hours by vacuum activation before testing. The test temperature is -196°C. The pore structure data such as the specific surface area and pore volume of the test sample are obtained by analyzing the isotherm.

[0084] In the present invention, the mass fraction of SiO2 in the active silicon powder is measured by thermogravimetric TG-DTA analysis of the sample using a TGA Q500analyzer instrument (test conditions are air atmosphere, heating rate 10°C / min).

[0085] In the present invention, the FT-IR spectrum test uses a Nexus670 Fourier transform infrared spectrometer (FT-IR) produced by Nicolet Company of the United States to analyze the skeleton vibration area of ​​the sample; during the test, the sample powder is first diluted with KBr to a mass fraction of about 3%, ground and mixed evenly with a mortar, and then pressed into a tablet to prepare a sample, which is then placed in a vacuum cell for testing, and the test resolution is 4cm- 1 , scanning times 32 times, test range 400~4000cm -1 .

[0086] In the following examples, all chemical reagents used are commercially available products and have not been specially purified unless otherwise mentioned;

[0087] In the present invention, 15 wt% to 40 wt% of hexamethonium hydroxide is purchased from Zhejiang Kent Catalytic Materials Co., Ltd.;

[0088] The sodium aluminate in the present invention is chemically pure, with a mass content of aluminum oxide ≥41% and a mass content of sodium oxide ≥31%;

[0089] The silica sol in the present invention is of ammonium type, with a silica mass content of 40%;

[0090] In the present invention, hexamethylbenzene bromide HMBr2 is purchased from Acros, with a mass fraction of >98%;

[0091] The white carbon black in the present invention is chemically pure, SiO2>91%;

[0092] The pseudo-boehmite in the present invention has an aluminum oxide mass content of 70.3%.

[0093] Example 1

[0094] This embodiment provides a cubic nano EU-1 molecular sieve, and the synthesis method is as follows:

[0095] Sodium aluminate was dissolved in deionized water to obtain 22.8 wt% solution A. Active silicon powder was dissolved in deionized water to obtain 32.8 wt% solution B. The 32.8 wt% solution B was added to the 22.8 wt% solution A within 10 min under stirring at 120 rpm and reacted to form gel at 20°C. Then, 25 wt% aqueous solution of hexamethylammonium hydroxide HM(OH)2 was added and stirred for 1 h. Then, the pH value was adjusted to 11.8 with 22 wt% aqueous solution of sodium hydroxide to obtain an initial gel. The gel was allowed to stand for aging at 20°C for 30 min. Then, the initial gel was transferred to a stainless steel reaction tank and sealed. After pre-crystallization at 120°C for 2 h, the gel was taken out and re-introduced into 180°C for crystallization for 48 h to obtain a crystallized product. The crystallized product was cooled, filtered, washed and dried to obtain a final solid product.

[0096] The final solid product obtained is EU-1 molecular sieve E1, and the XRD test is shown in the attached Figure 1 ; The molar ratio of silicon to aluminum in E1 is 57.1, and the SEM photo of E1 is shown in Figure 2 ,Depend on Figure 2 It can be seen that the average grain size of E1 is 80nm and the specific surface area S BET 440m 2 / g, micropore volume V micro 0.29cm 3 / g.

[0097] In the above, the active silicon powder is active methyltrimethoxysilane; the molar ratio of the aqueous solution of hexamethylammonium hydroxide HM(OH)2, methyltrimethoxysilane, sodium aluminate, aqueous sodium hydroxide and deionized water is 12:40:1:20:600; the preparation of the active methyltrimethoxysilane includes weighing sodium hydroxide, sodium fluoride and 25% ammonia solution, adding them to deionized water and dissolving them uniformly, adding methanol and placing the solution in a 5°C water bath; weighing methyltrimethoxysilane, adding it uniformly to the above solution under stirring at 30rpm, stirring for another 2 minutes, transferring it into a container and standing it at 30°C for 5 hours to obtain a sol, and rotary evaporating the solvent therein under vacuum conditions at 80°C until a solid block is precipitated, wherein the molar ratio of the treatment reagent / SiO2 is 0.05; the molar ratio of the solvent II / SiO2 is 10; OH - / SiO2 molar ratio 10.

[0098] The solid block obtained in the above preparation was treated with 1% citric acid aqueous solution at a liquid-solid mass ratio of about 6:1, and then acid exchanged and activated at 80°C for 1.5 hours, washed with deionized water until electrically neutral, and dried at 120°C. The temperature was then raised to 600°C at a rate of 3°C / min, and calcined at a constant temperature for 1.5 hours to obtain active methyltrimethoxysilane, which was recorded as sample SG1.

[0099] The specific surface area of ​​sample SG1 is S BET 510m 2 / g, pore volume = 2.4 cm 3 / g, SiO2 mass fraction is 99%, Figure 4 It can be seen that compared with silica A200, sample SG1 has a vibration frequency of no more than 600 cm -1 There are more non-240cm areas in the characteristic area -1 Nearby characteristic peaks; UV-Raman detected its vibration frequency at 335cm -1 、400cm -1 and 4480cm -1 The peak area of ​​the characteristic peak near 240cm -1 Characteristic peaks near 240cm -1 The sum of the peak areas of the nearby characteristic peaks is no more than 600 cm -1 The total area of ​​characteristic peaks in the characteristic region is 78%. Figure 4 In the UV-Raman spectrum of sample SG1, due to peak overlap, 335cm -1 、400cm -1 and 480cm -1 Nearby characteristic peaks overlap.

[0100] Depend on Figure 3 It can be seen that the silicon oxide particles in sample SG1 are uniform and dispersed; Figure 5 It can be seen that compared with silica A200, sample SG1 has a larger low-temperature adsorption capacity for nitrogen, and the specific surface area and pore volume obtained from the curve are larger; Figure 6 It can be seen that the signal peak of silanol in the corresponding FT-IR spectrum of sample SG1 is stronger (usually, the larger the peak area at the characteristic position, the higher the surface silanol concentration of the sample).

[0101] Example 2

[0102] This embodiment provides a cubic nano EU-1 molecular sieve, and the synthesis method is as follows:

[0103] Aluminum nitrate was dissolved in deionized water to obtain 23.1wt% solution A. Active silicon powder was dissolved in deionized water to obtain 31.5wt% solution B. The 31.5wt% solution B was added dropwise to the 23.1wt% solution A within 60min under stirring at 25rpm and reacted to form gel at 25°C. Hexamethylammonium bromide HMBr2 and 25wt% hexamethylammonium hydroxide HM(OH)2 methanol solution were added and stirred for 2h. The pH value was adjusted to 12.5 with 25wt% tetraethylammonium hydroxide aqueous solution to obtain an initial gel. The gel was allowed to stand for aging at 25°C for 3h. The initial gel was then transferred to a stainless steel reaction tank and sealed. After pre-crystallization at a hydrothermal temperature of 100°C for 6h, the gel was taken out and re-introduced into a hydrothermal temperature of 195°C for crystallization for 24h to obtain a crystallized product. The crystallized product was cooled, filtered, washed and dried to obtain a final solid product.

[0104] In the above, the active silicon powder is white carbon black, and the preparation method is the same as that of Example 1; the molar ratio of the hexamethylammonium bromide HMBr2 and the hexamethylammonium hydroxide HM(OH)2 methanol solution, white carbon black, aluminum nitrate, tetraethylammonium hydroxide aqueous solution and deionized water is 12:120:1:30:900, wherein the mass ratio of the hexamethylammonium bromide HMBr2 and the hexamethylammonium hydroxide HM(OH)2 methanol solution is 1:6.

[0105] The final solid product obtained is EU-1 molecular sieve E2; the silicon-aluminum molar ratio in E2 is 113.4, the average grain size of E1 is 55nm, and the specific surface area is S BET 425m 2 / g, micropore volume V micro 0.35cm 3 / g.

[0106] Comparative Example 1

[0107] This comparative example provides a EU-1 molecular sieve

[0108] The initial gel was prepared according to the synthesis method of Example 1, except that the initial gel was directly crystallized under hydrothermal conditions at a temperature of 180° C. for 48 h without pre-crystallization to induce nucleation.

[0109] The final solid product obtained is EU-1 molecular sieve D1; the molar ratio of silicon to aluminum in D1 is 39, the crystal size of D1 is about 210nm, and the specific surface area is S BET 505m 2 / g, micropore volume V micro 0.33cm 3 / g, and the crystals agglomerated to form a spindle-shaped (ellipsoid) morphology.

[0110] Comparative Example 2

[0111] This comparative example provides a EU-1 molecular sieve

[0112] The initial gel was prepared according to the synthesis method of Example 1, except that hexamethonium bromide was used to replace the 25 wt % hexamethonium hydroxide HM(OH)2 methanol solution, and 32 wt % sodium hydroxide aqueous solution was used to adjust the pH value to 11.9.

[0113] The final solid product obtained is EU-1 molecular sieve D2, the silicon-aluminum molar ratio in D2 is 4:1, the average grain size of D2 is 310nm, and the specific surface area is S BET 456m 2 / g, micropore volume V micro 0.37cm 3 / g, and the morphology is approximately ellipsoidal.

[0114] The above-mentioned comparative examples 1-2 are EU-1 molecular sieves synthesized under differentiated conditions without pre-crystallization-induced nucleation and without adjusting the cation ratio, and their particle sizes are all around 2 to 4 μm and do not have a blocky morphology. In sharp contrast, in Examples 1-2 of the present invention, pre-crystallization-induced nucleation and adjustment of the cation ratio are used to significantly reduce the grain size of the EU-1 molecular sieve to below 0.2 μm, and at the same time, the EU-1 molecular sieve obtained by adjusting the molar ratio of the template to the alkali source has a blocky morphology and is cubic; the obtained EU-1 molecular sieve has a much smaller grain size than the EU-1 molecular sieve synthesized in Comparative Examples 1-2, and has excellent catalytic performance. It can be seen that the pre-crystallization-induced nucleation of the present invention is very effective in reducing the grain size. At the same time, by adjusting the cation ratio in the crystallization system, the uniformity, high dispersibility, and crystallinity of the product grain morphology are effectively improved, and a special morphology is obtained, thereby achieving better technical effects.

[0115] Example 3

[0116] This embodiment provides a cubic nano EU-1 molecular sieve

[0117] The synthesis method of Example 1 is followed, except that the molar ratio of hexamethylammonium hydroxide HM(OH)2 aqueous solution, tetramethoxysilane, sodium aluminate, sodium hydroxide aqueous solution and deionized water is 15:60:1:0:900.

[0118] The final solid product obtained is EU-1 molecular sieve E3; the silicon-aluminum molar ratio in E3 is 47.

[0119] Example 4

[0120] This embodiment provides a cubic nano EU-1 molecular sieve

[0121] The synthesis method of Example 1 is followed, except that the molar ratio of hexamethylammonium hydroxide HM(OH)2 aqueous solution, tetramethoxysilane, sodium aluminate, sodium hydroxide aqueous solution and deionized water is 15:60:1:5:900.

[0122] The final solid product obtained is EU-1 molecular sieve E4; the silicon-aluminum molar ratio in E4 is 4:1.

[0123] Example 5

[0124] This embodiment provides a cubic nano EU-1 molecular sieve

[0125] The synthesis method of Example 1 is followed, except that the molar ratio of hexamethylammonium hydroxide HM(OH)2 aqueous solution, tetramethoxysilane, sodium aluminate, sodium hydroxide aqueous solution and deionized water is 15:60:1:10:900.

[0126] The final solid product obtained is EU-1 molecular sieve E5; the silicon-aluminum molar ratio in E5 is 43.

[0127] Example 6

[0128] This embodiment provides a cubic nano EU-1 molecular sieve

[0129] The synthesis method of Example 1 is followed, except that the molar ratio of hexamethylammonium hydroxide HM(OH)2 aqueous solution, tetramethoxysilane, sodium aluminate, sodium hydroxide aqueous solution and deionized water is 15:60:1:20:900.

[0130] The final solid product obtained is EU-1 molecular sieve E6; the silicon-aluminum molar ratio in E6 is 42.5.

[0131] Example 7

[0132] This embodiment provides a cubic nano EU-1 molecular sieve

[0133] The synthesis method of Example 1 is followed, except that the molar ratio of hexamethylammonium hydroxide HM(OH)2 aqueous solution, tetramethoxysilane, sodium aluminate, sodium hydroxide aqueous solution and deionized water is 15:60:1:30:900.

[0134] The final solid product obtained is EU-1 molecular sieve E7; the silicon-aluminum molar ratio in E7 is 42.2.

[0135] Example 8

[0136] This embodiment provides a cubic nano EU-1 molecular sieve

[0137] The synthesis method of Example 1 is followed, except that the molar ratio of hexamethylammonium hydroxide HM(OH)2 aqueous solution, tetramethoxysilane, sodium aluminate, sodium hydroxide aqueous solution and deionized water is 15:60:1:60:900.

[0138] The final solid product obtained is EU-1 molecular sieve E8; the silicon-aluminum molar ratio in E8 is 40.

[0139] The morphology and grain size statistics of the cubic nano EU-1 molecular sieves prepared in the above Examples 3-8 are shown in Table 1 below;

[0140] Table 1

[0141]

[0142] Example 9

[0143] This embodiment provides a cubic nano EU-1 molecular sieve

[0144] The synthesis method of Example 1 is followed, except that the molar ratio of hexamethylammonium hydroxide HM(OH)2 aqueous solution, tetramethoxysilane, sodium aluminate, sodium hydroxide aqueous solution and deionized water is 12:30:1:20:500; and the crystallization temperature is 140°C.

[0145] The final solid product obtained is EU-1 molecular sieve E9; the silicon-aluminum molar ratio in E9 is 25.

[0146] Example 10

[0147] This embodiment provides a cubic nano EU-1 molecular sieve

[0148] The synthesis method of Example 1 is followed, except that the molar ratio of hexamethylammonium hydroxide HM(OH)2 aqueous solution, tetramethoxysilane, sodium aluminate, sodium hydroxide aqueous solution and deionized water is 16:50:1:20:500; and the crystallization temperature is 160°C.

[0149] The final solid product obtained is EU-1 molecular sieve E10; the silicon-aluminum molar ratio in E10 is 43.

[0150] Embodiment 11

[0151] This embodiment provides a cubic nano EU-1 molecular sieve

[0152] The synthesis method of Example 1 is followed, except that the molar ratio of hexamethylammonium hydroxide HM(OH)2 aqueous solution, tetramethoxysilane, sodium aluminate, sodium hydroxide aqueous solution and deionized water is 18:75:1:20:500; and the crystallization temperature is 180°C.

[0153] The final solid product obtained is EU-1 molecular sieve E11; the silicon-aluminum molar ratio in E11 is 67.

[0154] Example 12

[0155] This embodiment provides a cubic nano EU-1 molecular sieve

[0156] The synthesis method of Example 1 is followed, except that the molar ratio of hexamethylammonium hydroxide HM(OH)2 aqueous solution, tetramethoxysilane, sodium aluminate, sodium hydroxide aqueous solution and deionized water is 20:90:1:20:500; and the crystallization temperature is 160°C.

[0157] The final solid product obtained is EU-1 molecular sieve E12; the silicon-aluminum molar ratio in E12 is 75.

[0158] Embodiment 13

[0159] This embodiment provides a cubic nano EU-1 molecular sieve

[0160] The synthesis method of Example 1 is followed, except that the molar ratio of hexamethylammonium hydroxide HM(OH)2 aqueous solution, tetramethoxysilane, sodium aluminate, sodium hydroxide aqueous solution and deionized water is 18:100:1:20:500; and the crystallization temperature is 180°C.

[0161] The final solid product obtained is EU-1 molecular sieve E13; the silicon-aluminum molar ratio in E13 is 89.

[0162] Embodiment 14

[0163] This embodiment provides a cubic nano EU-1 molecular sieve

[0164] The synthesis method of Example 1 is followed, except that the molar ratio of hexamethylammonium hydroxide HM(OH)2 aqueous solution, tetramethoxysilane, sodium aluminate, sodium hydroxide aqueous solution and deionized water is 20:120:1:20:500; and the crystallization temperature is 180°C.

[0165] The final solid product obtained is EU-1 molecular sieve E14; the silicon-aluminum molar ratio in E14 is 107.

[0166] Embodiment 15

[0167] This embodiment provides a cubic nano EU-1 molecular sieve

[0168] The synthesis method of Example 1 is followed, except that the molar ratio of hexamethylammonium hydroxide HM(OH)2 aqueous solution, tetramethoxysilane, sodium aluminate, sodium hydroxide aqueous solution and deionized water is 20:150:1:20:500; and the crystallization temperature is 175°C.

[0169] The final solid product obtained is EU-1 molecular sieve E15; the silicon-aluminum molar ratio in E15 is 130.

[0170] Example 16

[0171] This embodiment provides a cubic nano EU-1 molecular sieve

[0172] The synthesis method of Example 1 is followed, except that the molar ratio of hexamethylammonium hydroxide HM(OH)2 aqueous solution, tetramethoxysilane, sodium aluminate, sodium hydroxide aqueous solution and deionized water is 20:180:1:20:500; and the crystallization temperature is 190°C.

[0173] The final solid product obtained is EU-1 molecular sieve E16; the silicon-aluminum molar ratio in E16 is 163.

[0174] The morphology and grain size statistics of the cubic nano EU-1 molecular sieves prepared in Examples 9-16 are shown in Table 2 below;

[0175] Table 2

[0176]

[0177] Embodiment 17

[0178] This embodiment provides a cubic nano EU-1 molecular sieve

[0179] The synthesis method of Example 1 is followed, except that the 25 wt % hexamethonium hydroxide HM(OH)2 solution is replaced by a template precursor, and the molar ratio of 1,6-dibromohexane:trimethylamine:acetone in the template precursor is 10:50:20.

[0180] The final solid product obtained is EU-1 molecular sieve E17; the silicon-aluminum molar ratio in E17 is 53.

[0181] Embodiment 18

[0182] This embodiment provides a cubic nano EU-1 molecular sieve

[0183] The synthesis method of Example 1 is followed, except that the 25 wt % hexamethonium hydroxide HM(OH)2 solution is replaced by a template precursor, and the molar ratio of 1,6-dibromohexane:trimethylamine:acetone in the template precursor is 3:5:10.

[0184] The final solid product obtained is EU-1 molecular sieve E18; the silicon-aluminum molar ratio in E18 is 53.

[0185] Embodiment 19

[0186] This embodiment provides a cubic nano EU-1 molecular sieve

[0187] The synthesis method of Example 1 is followed, except that the 25 wt % hexamethonium hydroxide HM(OH)2 solution is replaced by a template precursor, and the molar ratio of 1,6-dibromohexane:trimethylamine:acetone in the template precursor is 25:50:25.

[0188] The final solid product obtained is EU-1 molecular sieve E19; the silicon-aluminum molar ratio in E19 is 58.

[0189] Embodiment 20

[0190] This embodiment provides a cubic nano EU-1 molecular sieve

[0191] The synthesis method of Example 1 is followed, except that the 25 wt % hexamethonium hydroxide HM(OH)2 solution is replaced by a template precursor, and the molar ratio of 1,6-dibromohexane:trimethylamine:acetone in the template precursor is 15:60:30.

[0192] The final solid product obtained is EU-1 molecular sieve E20; the silicon-aluminum molar ratio in E20 is 56.

[0193] Embodiment 21

[0194] This embodiment provides a cubic nano EU-1 molecular sieve

[0195] The synthesis method of Example 1 is followed, except that the 25 wt % hexamethonium hydroxide HM(OH)2 solution is replaced by a template precursor, and the molar ratio of 1-chloro-6-bromohexane:trimethylamine:acetone in the template precursor is 10:50:20.

[0196] The final solid product obtained is EU-1 molecular sieve E21; the silicon-aluminum molar ratio in E21 is 55.

[0197] The morphology and average grain size statistics of the cubic nano EU-1 molecular sieves prepared in Examples 17-21 are shown in Table 3 below;

[0198] Table 3

[0199]

[0200] Embodiment 22

[0201] This embodiment provides a cubic nano EU-1 molecular sieve, and the synthesis method is as follows:

[0202] Sodium aluminate was dissolved in deionized water to obtain 23.6 wt% solution A. Silica sol was dissolved in deionized water to obtain 32.3 wt% solution B. The 32.3 wt% solution B was added dropwise to the 23.6 wt% solution A within 120 min under stirring at 180 rpm and reacted to form gel at 22° C. Then, a 25 wt% aqueous solution of hexamethylammonium hydroxide HM(OH)2 was added and stirred for 1 h. The pH value was adjusted to 13.1 with a 25 wt% aqueous solution of tetraethylammonium hydroxide to obtain an initial gel. The gel was aged at 22° C. for 1.5 h. The initial gel was then transferred to a stainless steel reaction tank and sealed. After pre-crystallization at a hydrothermal temperature of 120° C. for 4 h, the gel was crystallized at a hydrothermal temperature of 180° C. for 48 h to obtain a crystallized product. The crystallized product was cooled, filtered, washed, and dried to obtain a final solid product.

[0203] In the above, the molar ratio of the hexamethylammonium hydroxide HM(OH)2 aqueous solution, silica sol, sodium aluminate, tetraethylammonium hydroxide aqueous solution and deionized water is 1:60:1:2:60.

[0204] The final solid product obtained is EU-1 molecular sieve E22; the molar ratio of silicon to aluminum in E22 is 52.8, the average grain size of E22 is 130nm, and the specific surface area is S BET 420m 2 / g, micropore volume V micro 0.31cm 3 / g.

[0205] Embodiment 23

[0206] This embodiment provides a cubic nano EU-1 molecular sieve, and the synthesis method is as follows:

[0207] Sodium aluminate was dissolved in deionized water to obtain 20.9 wt% solution A. Silica sol was dissolved in deionized water to obtain 30.9 wt% solution B. The 30.9 wt% solution B was added dropwise to the 20.9 wt% solution A within 240 min under stirring at a rate of 300 rpm and reacted to form gel at 22° C. Then, hexamethylammonium bromide HMBr2 and 25 wt% hexamethylammonium hydroxide HM(OH)2 aqueous solution were added, stirred for 1 h, and then the pH value was adjusted to 11.9 with 15 wt% sodium hydroxide aqueous solution to obtain an initial gel, which was allowed to stand for aging at 22° C. for 3.5 h, and then the initial gel was transferred to a stainless steel reaction tank and sealed, and pre-crystallized at a hydrothermal temperature of 115° C. for 5 h, and then crystallized at a hydrothermal temperature of 185° C. for 42 h to obtain a crystallized product, and the crystallized product was cooled, filtered, washed, and dried to obtain a final solid product.

[0208] In the above, the molar ratio of the aqueous solution of hexamethylammonium bromide HMBr2 and hexamethylammonium hydroxide HM(OH)2, silica sol, sodium aluminate, aqueous sodium hydroxide and deionized water is 20:180:1:60:800, wherein the mass ratio of the aqueous solution of hexamethylammonium bromide HMBr2 and hexamethylammonium hydroxide HM(OH)2 is 1:8.

[0209] The final solid product obtained is EU-1 molecular sieve E23; the molar ratio of silicon to aluminum in E23 is 151.8, the average grain size of E23 is 75nm, and the specific surface area is S BET 424m 2 / g, micropore volume V micro 0.38cm 3 / g.

[0210] Embodiment 24

[0211] This embodiment provides a cubic nano EU-1 molecular sieve, and the synthesis method is as follows:

[0212] Sodium aluminate was dissolved in deionized water to obtain 22.7 wt% solution A. White carbon black was dissolved in deionized water to obtain 31.0 wt% solution B. The 31.0 wt% solution B was added dropwise to the 22.7 wt% solution A within 25 min under stirring at a rate of 50 rpm and reacted to form a gel at 22° C. Then, 25 wt% aqueous solution of hexamethylammonium hydroxide HM(OH)2 and hexamethylammonium bromide were added, stirred for 1 h, and the pH value was adjusted to 12 with 25 wt% tetramethylammonium hydroxide methanol solution to obtain an initial gel, which was allowed to stand for aging at 22° C. for 0.5 h, and then the initial gel was transferred to a stainless steel reaction tank and sealed, and pre-crystallized at a hydrothermal temperature of 80° C. for 10 h, and then crystallized at a hydrothermal temperature of 175° C. for 72 h to obtain a crystallized product, and the crystallized product was cooled, filtered, washed, and dried to obtain a final solid product.

[0213] In the above, the molar ratio of the hexamethonium hydroxide HM(OH)2 aqueous solution to hexamethonium bromide, white carbon, sodium aluminate, tetramethylammonium hydroxide methanol solution and deionized water is 12:70:1:25:120, wherein the mass ratio of the hexamethonium hydroxide HM(OH)2 aqueous solution to hexamethonium bromide is 4:1.

[0214] The final solid product obtained is EU-1 molecular sieve E24; the molar ratio of silicon to aluminum in E24 is 69.1, the average grain size of E24 is 140nm, and the specific surface area is S BET 426m 2 / g, micropore volume V micro 0.33cm 3 / g.

[0215] Embodiment 25

[0216] This embodiment provides a cubic nano EU-1 molecular sieve, and the synthesis method is as follows:

[0217] Pseudo-boehmite was dissolved in deionized water to obtain 22.9wt% solution A. Silica sol was dissolved in deionized water to obtain 32.1wt% solution B. The 32.1wt% solution B was added dropwise to the 22.9wt% solution A within 50min under stirring at 240rpm and reacted to form gel at 22°C. Then, a 25wt% aqueous solution of hexamethylammonium hydroxide HM(OH)2 was added and stirred for 1h. Then, the pH value was adjusted to 10.8 with a 32wt% sodium hydroxide solution to obtain an initial gel. The gel was aged at 22°C for 2h. Then, the initial gel was transferred to a stainless steel reaction tank and sealed. After pre-crystallization at 95°C for 5h, the gel was crystallized at 180°C for 48h to obtain a crystallized product. The crystallized product was cooled, filtered, washed, and dried to obtain a final solid product.

[0218] In the above, the molar ratio of the hexamethonium hydroxide HM(OH)2 aqueous solution, silica sol, pseudo-boehmite, sodium hydroxide solution and deionized water is 14:60:1:30:180.

[0219] The final solid product obtained is EU-1 molecular sieve E25; the molar ratio of silicon to aluminum in E25 is 51.2, the average grain size of E25 is 95nm, and the specific surface area is S BET 435m 2 / g, micropore volume V micro 0.35cm 3 / g.

[0220] Preparation Example 1

[0221] This preparation example provides a catalyst, and the preparation method is as follows:

[0222] Take 20 g of the EU-1 molecular sieve obtained in Example 1 and mix it with an ammonium nitrate solution with a mass concentration of 10% at a solid-liquid mass ratio of 6, exchange it at a temperature of 90°C for 1 hour, exchange it twice, filter it, and dry it at a temperature of 135°C for 3 hours to obtain the treated EU-1 molecular sieve.

[0223] 2.7 g of the treated EU-1 molecular sieve was mixed with 17.8 g of pseudo-boehmite (alumina content of 70.3%), 0.2 g of sesbania powder, 0.5 ml of 50% nitric acid aqueous solution and 10 ml of deionized water in a molecular sieve to alumina dry mass ratio of 20:80, extruded into strips, left overnight, dried at 110°C for 2 h, and then calcined at 550°C for 3 h in an air atmosphere to obtain a catalyst carrier, which was shaped and pelletized into About carrier particles.

[0224] Take 20g of the above-mentioned dried carrier particles, add them into 12ml of chloroplatinic acid solution with a platinum concentration of 0.34wt% at room temperature, use the impregnation method to impregnate equal volume for 24h, then dry at 100°C for 4h, and finally heat to 550°C in an air atmosphere and calcine for 3h to obtain catalyst C1.

[0225] Preparation Example 2

[0226] This preparation example provides a catalyst

[0227] Catalyst C2 was prepared according to the preparation method of Preparation Example 1, except that the EU-1 molecular sieve prepared in Example 10 was used instead of the EU-1 molecular sieve prepared in Example 1.

[0228] Preparation Example 3

[0229] This preparation example provides a catalyst

[0230] Catalyst C3 was prepared according to the preparation method of Preparation Example 1, except that the EU-1 molecular sieve prepared in Example 16 was used instead of the EU-1 molecular sieve prepared in Example 1.

[0231] Preparation Example 4

[0232] This preparation example provides a catalyst

[0233] Catalyst C4 was prepared according to the preparation method of Preparation Example 1, except that the EU-1 molecular sieve prepared in Example 22 was used instead of the EU-1 molecular sieve prepared in Example 1.

[0234] Preparation Example 5

[0235] This preparation example provides a catalyst

[0236] Catalyst C5 was prepared according to the preparation method of Preparation Example 1, except that the EU-1 molecular sieve prepared in Comparative Example 1 was used instead of the EU-1 molecular sieve prepared in Example 1.

[0237] In order to further illustrate the advancement of the EU-1 molecular sieve prepared by the present invention, the catalysts C1-C5 prepared by the EU-1 molecular sieve prepared by the present invention were subjected to the following performance evaluation;

[0238] (I) The isomerization reaction of C8 aromatics including m-xylene, o-xylene and ethylbenzene was evaluated under the following operating conditions: reaction temperature 380°C, reaction pressure 1 MPa, hydrogen-to-hydrocarbon molar ratio 4, weight hourly space velocity 4 h -1 .

[0239] The raw material C8 aromatics composition: 15wt% ethylbenzene (EB), 60wt% meta-xylene (MX), 25wt% o-xylene (OX);

[0240] Evaluation index: According to the activity (the concentration of p-xylene in xylene in the product PX / ΣX and the ethylbenzene conversion rate C EB ) and selectivity (C8 aromatics yield Y C8A ) to evaluate the catalyst performance.

[0241] The relevant calculation formulas and definitions based on the mass content of the components are as follows:

[0242] ΣX=OX+PX+MX

[0243] C8A=EB+ΣX

[0244] PX / ΣX=PX / (PX+MX+OX)×100%

[0245]

[0246]

[0247] The reaction performance results of catalysts C1-C5 prepared in Preparation Examples 1-5 of the present invention are statistically shown in Table 4 below;

[0248] Table 4

[0249] catalyst C1 C2 C3 C4 C5 PX / ΣX 23.6 24.2 24.1 23.9 23.8 <![CDATA[C EB ]]> 28.9 28.1 28.4 28.4 28.1 <![CDATA[Y C8A ]]> 97.7 97.8 97.7 97.7 97.6

[0250] (II) The alkylation reaction of aromatic rings was evaluated by mainly using materials including benzene, toluene, methanol and ethanol. The operating conditions were as follows: reaction temperature 460°C, reaction pressure 0.5 MPa, hydrogen-to-hydrocarbon molar ratio 3, and weight hourly space velocity 4 h -1 .

[0251] Material composition: The molar ratio of aromatic hydrocarbons (benzene or toluene) to alcohols (methanol or ethanol) is 2;

[0252] Evaluation index: The catalyst performance is evaluated based on the activity (concentration of xylene in the product PX / Σtotal molar amount of liquid products, and feedstock conversion rate C) and ethylbenzene selectivity (concentration of ethylbenzene in the product PX / Σtotal molar amount of liquid products).

[0253] The relevant calculation formulas and definitions based on the mass content of the components are as follows:

[0254] C8A=EB+ΣX

[0255]

[0256] Taking the alkylation of toluene and methanol as an example, the reaction performance results of the catalysts C1-C5 prepared in Preparation Examples 1-5 of the present invention are statistically shown in Table 5 below;

[0257] Table 5

[0258]

[0259]

[0260] In the above Table 5, C Toluene Represents the conversion rate of toluene; S Xylene Indicates the selectivity of xylene; S EB Indicates the selectivity of ethylbenzene.

[0261] It should be noted that the embodiments described above are only used to explain the present invention and do not constitute any limitation to the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory words, rather than restrictive words. The present invention may be modified as specified within the scope of the claims of the present invention, and the present invention may be revised without departing from the scope and spirit of the present invention. Although the present invention described therein relates to specific methods, materials and embodiments, it does not mean that the present invention is limited to the specific examples disclosed therein, on the contrary, the present invention can be extended to all other methods and applications with the same functions.

Claims

1. A EU-1 molecular sieve, characterized in that The crystal form of the EU-1 molecular sieve is tetragonal; the silicon-aluminum molar ratio of the EU-1 molecular sieve is 5 to 500, the average crystal size of the EU-1 molecular sieve is ≤ 600 nm, and the specific surface area S of the EU-1 molecular sieve is BET 390m 2 / g~700m 2 / g, micropore volume V micro 0.22cm 3 / g~0.60cm 3 / g.

2. The EU-1 molecular sieve according to claim 1, characterized in that The average particle size of the EU-1 molecular sieve particles is 2nm to 200nm; And / or, the EU-1 molecular sieve contains eight regular vertices, preferably, the EU-1 molecular sieve is a rectangular parallelepiped or a cubic shape; And / or, the specific surface area S of the EU-1 molecular sieve BET 420m 2 / g~514m 2 / g, micropore volume V micro 0.28cm 3 / g~0.44cm 3 / g.

3. A method for synthesizing the EU-1 molecular sieve according to claim 1 or 2, characterized in that: The method comprises the steps of mixing a template, a silicon source, an aluminum source, an alkali source and a solvent I, aging and crystallizing the mixture to obtain the EU-1 molecular sieve.

4. The synthesis method according to claim 3, characterized in that The silicon source is selected from at least one of silica sol, water glass, kaolin and white carbon black or selected from active silicon powder; preferably, in the ultraviolet Raman spectrum of the active silicon powder, at a vibration frequency of 240cm -1 There are characteristic peaks nearby, with a vibration frequency no greater than 600cm -1 In the characteristic area, there is at least one non-240cm -1 Characteristic peaks near 240cm -1 The sum of the peak areas of the nearby characteristic peaks is no more than 600 cm -1 The characteristic peak area of ​​the characteristic region is 20% to 98% of the total area; And / or, the aluminum source is selected from at least one of aluminum sulfate, sodium aluminate, aluminum chloride, aluminum nitrate and pseudo-boehmite; And / or, the alkali source is selected from at least one of tetraethylammonium hydroxide aqueous solution, tetramethylammonium hydroxide methanol solution, ammonia water, sodium hydroxide aqueous solution, potassium hydroxide aqueous solution, and rubidium hydroxide aqueous solution; preferably, the mass concentration of the tetraethylammonium hydroxide aqueous solution is 10% to 40%, and / or the mass concentration of the tetramethylammonium hydroxide methanol solution is 15% to 40%, and / or the mass concentration of the ammonia water is 15% to 40%, and / or the mass concentration of the sodium hydroxide aqueous solution is 10% to 40%, and / or the mass concentration of the potassium hydroxide aqueous solution is 5% to 20%, and / or the mass concentration of the rubidium hydroxide aqueous solution is 1% to 10%; And / or, the template agent is selected from at least one of hexamethonium bromide, an aqueous solution or methanol solution of hexamethonium hydroxide, and a template agent precursor; preferably, the template agent precursor is prepared by dissolving a dihalogenated alkane and a monoamine in an organic solvent; preferably, the dihalogenated alkane is 1,6-dibromohexane or 1-chloro-6-bromohexane; preferably, the monoamine is trimethylamine or triethylamine and a mixture thereof in any proportion; preferably, the organic solvent is ethanol or acetone; the molar ratio of the dihalogenated alkane, the monoamine and the organic solvent is (1-50): (3-100): (5-50), preferably (3-25): (5-60): (10-30); further preferably, the mass concentration of the aqueous solution or methanol solution of hexamethonium hydroxide is 5% to 45%; And / or, the solvent I is at least one of deionized water, ethanol, glycerol, acetone, n-butanol, imidazole-type ionic liquid, and [bmim]PF6 anionic ionic liquid.

5. The synthesis method according to claim 3 or 4, characterized in that: The template, silicon source, aluminum source, alkali source and solvent I are mixed to obtain an initial gel mixture; preferably, the molar ratio of the template, silicon source, aluminum source, alkali source and solvent I is (1-20): (10-180): 1: (0-60): (50-900), preferably (1-20): (30-180): 1: (0-60): (60-900); And / or, the aging is carried out at a temperature of 20°C to 25°C, and the aging time is 0h to 4h, preferably 0.5h to 4h; And / or, the crystallization adopts a staged crystallization process, including pre-crystallization and crystallization; preferably, the pre-crystallization temperature is 30°C to 120°C, preferably 60°C to 120°C; the pre-crystallization time is 0.5h to 12h, preferably 2h to 10h; further preferably, the crystallization temperature is 120°C to 200°C, preferably 150°C to 195°C; the crystallization time is 24h to 120h, preferably 24h to 72h; And / or, the crystallization further includes the steps of cooling, filtering, washing and drying.

6. Use of the EU-1 molecular sieve as claimed in claim 1 or 2 or the EU-1 molecular sieve prepared by the synthesis method of any one of claims 3 to 6 in aromatic ring alkylation or alkyl side chain aromatic isomerization reaction.

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