Molecular sieve as well as synthesis method and application thereof

Abstract

The invention discloses a molecular sieve and a synthesis method and application thereof, and the method comprises the following steps: forming a dispersion liquid from a silicon source, an aluminum source, a template agent and an alkali source, and then crystallizing, washing, drying and roasting; wherein the template agent is selected from at least one of a substance group consisting of N, N-bis (tripropylammonium hexamethylene)-N, N-dipropylammonium hydroxide, a tripolymer TPA, C22H45-N (CH3) 2-C6H12-N (CH3) 2-C6H13] Br2, (tri (dodecyl dimethyl-2-hydroxypropyl)-citric acid triester ammonium chloride and dodecyl dimethyl benzyl ammonium chloride. According to the molecular sieve disclosed by the invention, the proportion of Al located at the cross point of pore channels in the skeleton Al is high, and the molecular sieve is especially suitable for alkylation reaction.

Description

Technical Field

[0001] The invention relates to a molecular sieve and a synthesis method and application thereof. Background Art

[0002] ZSM-5 zeolite is a high-silicon crystalline aluminosilicate widely used in catalysts and adsorbents. 4 The tetrahedrons (T=Si,Al) are interconnected within the framework, and the catalytically active species such as protons, metal cations and metal oxygen cations in the pores are used to balance the catalytic activity of TO. 4 The aluminosilicate framework [Si n-m Al m O 2n ] m- The negative charge of the cationic species is 4 Tetrahedral bonding, the position of Al atoms on the crystal T site and their distribution in the framework clearly determine the location, structure and properties of the counter-ion species (catalytic active sites).

[0003] In industry, the alkylation reaction of benzene with methanol is mainly carried out using solid acid catalysts. Acid (B) is used, and ZSM-5 zeolite in particular is considered to be a good catalyst due to its unique acidity and pore structure.

[0004] CN100564489C discloses a method for regulating the B / L ratio by loading rare earth elements, phosphorus or boron to modify ZSM-5, thereby increasing the L acid / B acid ratio, and using it to catalyze petroleum cracking to prepare light olefins, thereby increasing the yield of light olefins.

[0005] CN105174285A discloses a method for regulating the distribution of aluminum in the framework of a ZSM-5 molecular sieve, a molecular sieve and an application thereof, specifically, mixing the ZSM-5 molecular sieve with an aqueous solution of ammonium acetate to obtain a uniform suspension, then adding an aqueous solution of ammonium hexafluorosilicate, and post-treating the ZSM-5 molecular sieve under stirring to obtain a ZSM-5 molecular sieve with a modified distribution of aluminum in the framework. While keeping the molar ratio of Si / Al in the framework unchanged, the ZSM-5 molecular sieve has more Single Al, which can improve the selectivity of light olefins and obtain a higher yield of ethylene and propylene.

[0006] CN 110372004 B discloses a method for regulating the microscopic aluminum distribution of a ZSM 5 molecular sieve and its application. First, cobalt ions are loaded onto a Na-ZSM 5 molecular sieve to obtain a Co-ZSM 5 molecular sieve, and then the Co-ZSM 5 molecular sieve is post-treated with ammonium hexafluorosilicate and ammonium acetate to obtain a ZSM5 molecular sieve after the microscopic aluminum distribution regulation treatment, which can achieve the regulation of the relative content of ortho-aluminum and single aluminum in the ZSM 5 molecular sieve and the increase of the relative content of ortho-aluminum. Summary of the invention

[0007] The key technical problem to be solved by the present invention is that the position of the B acidic site obtained by the prior art is uncontrollable; the present invention firstly finds that the template of the present invention can be used to synthesize a molecular sieve with adjustable positions and numbers of B and L acidic sites, thus simplifying the process flow. The present invention can adjust the position of B acid at different positions without changing the Si / Al ratio, while maintaining the inherent properties of the zeolite. It is also firstly found that the molecular sieve used as a catalyst in the alkylation process, especially in the alkylation reaction of benzene and methanol, has the characteristics of high single-pass conversion rate and good selectivity of the target product.

[0008] The acid sites of ZSM-5 can be divided into three types according to their exact location, namely, linear channels, sinusoidal channels and intersections. A large number of studies have shown that the distribution of aluminum in silica-alumina zeolites is not random, but is determined by the interaction between the template and the zeolite. Although all three types of channels can be considered as active B acid centers, considering that the pore size of the 10-membered ring channel is smaller than the intersection of the channel (the sinusoidal channel is Straight channel The intersection point is about The steric hindrance of the product or transition state is greater than the intersection in the 10-membered ring channel. Under different environments of the pores and pore intersections, the enthalpy and entropy of adsorbed reactants and transition states may be different. In summary, the position and distribution of Al atoms in the molecular sieve framework may be important factors affecting the activity and selectivity of the molecular sieve, because they affect the accessibility of molecules to acid sites and the spatial constraints of the reaction field in the pores. Therefore, there are still many challenges in this field to develop methods that can regulate the distribution of Al in the molecular sieve framework.

[0009] To achieve the above-mentioned object, according to the first aspect of the present invention, the present invention provides a method for synthesizing a molecular sieve, the method comprising: forming a dispersion liquid with a silicon source, an aluminum source, a template agent, and an alkali source, followed by crystallization, washing, drying, and calcining; wherein the template agent is selected from N,N-bis(tripropylammonium hexamethylene)-N,N-dipropylammonium hydroxide, trimer TPA, quaternary ammonium salt C 22 H 45 -N(CH 3 ) 2 -C 6 H 12-N(CH 3 ) 2 -C 6 H 13 ]Br 2 , at least one of the group consisting of tri(dodecyldimethyl-2-hydroxypropyl)-tris(citrate)ammonium chloride (CTTAC) and dodecyldimethylbenzyl ammonium chloride.

[0010] According to the second aspect of the present invention, the present invention provides the application of the synthesis method described in the present invention in the synthesis of silicon aluminum molecular sieves and / or silicon phosphorus aluminum molecular sieves, preferably in the synthesis of one or more molecular sieves of ZSM-5, ZSM-11, SAPO-34, MCM-22, SAPO-11.

[0011] According to a third aspect of the present invention, the present invention provides a molecular sieve synthesized by the synthesis method of the present invention, wherein the molecular sieve has a skeleton Al content of more than 90% at the intersection of pores.

[0012] According to a fourth aspect of the present invention, the present invention provides the use of the molecular sieve in an alkylation reaction, particularly preferably in an alkylation reaction with aromatic hydrocarbons and alcohols as raw materials, wherein the aromatic hydrocarbons are substituted or unsubstituted aromatic hydrocarbons of C6-C8, and the alcohols are C1-C3 alcohols.

[0013] The present invention discovers for the first time that the template of the present invention can be used to synthesize molecular sieves with adjustable positions and quantities of B and L acid sites, thereby simplifying the process flow. The present invention can adjust the location of B acid at different positions without changing the Si / Al ratio while maintaining the inherent properties of the zeolite.

[0014] The molecular sieve of the present invention has a high proportion of Al located at the intersection of pores in the framework Al. It is found for the first time that it is particularly suitable for alkylation, especially methanol toluene alkylation reaction. It has the characteristics of high single-pass conversion rate, high benzene conversion rate, high selectivity for toluene and xylene, etc. when used in the reaction. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 Shown is the XRD spectrum of the molecular sieve prepared in Examples 1-4 of the present invention;

[0016] Figure 2 is the SEM image of each sample; Figure 2 (a) is the SEM image of silicon aluminum nanosphere AS in Example 1, Figure 2 (b) shows a scanning electron microscope photograph of the molecular sieve prepared in Example 1 of the present invention, Figure 2 (c) shows a scanning electron microscope photograph of the molecular sieve prepared in Example 2 of the present invention, Figure 2(d) shows a scanning electron microscope photograph of the molecular sieve prepared in Comparative Example 1 of the present invention;

[0017] Figure 3 The ZSM-5 molecular sieve prepared in Example 1 of the present invention is shown 27 Al NMR spectrum; Figure 4 The ZSM-5 molecular sieve prepared in Comparative Example 1 of the present invention is shown 27 Al NMR spectrum. DETAILED DESCRIPTION

[0018] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0019] The present invention provides a method for synthesizing a molecular sieve, which comprises: forming a dispersion liquid with a silicon source, an aluminum source, a template agent, and an alkali source, followed by crystallization, washing, drying, and calcining; wherein the template agent is selected from N,N-bis(tripropylammoniumhexamethylene)-N,N-dipropylammonium hydroxide, trimer TPA, C 22 H 45 -N(CH 3 ) 2 -C 6 H 12 -N(CH 3 )-C 6 H 13 ]Br 2 , at least one of the group consisting of tri(dodecyldimethyl-2-hydroxypropyl)-tris(dodecyldimethyl-2-hydroxypropyl)-citrate triester ammonium chloride (CTTAC) and dodecyldimethylbenzyl ammonium chloride. The present invention firstly finds that the template of the present invention can be used to synthesize molecular sieves with adjustable positions and quantities of acid sites of B and L acids, thereby simplifying the process flow. The present invention can adjust the placement of B acid at different positions without changing the Si / Al ratio, while maintaining the inherent properties of the zeolite.

[0020] In the specific operation process, a silicon source and an aluminum source can be added to a solution formed by a template and deionized water; then an alkali source solution is added to the above solution, and then the resulting mixture is continuously stirred at room temperature for 2 hours to obtain an emulsion solution, followed by the crystallization, washing, drying and calcination.

[0021] In the present invention, the amount of the template agent can be selected in a wide range, the purpose is to adjust the position of the B acid, so the amount is generally: the amount of the template agent added and the silicon source (in the form of SiO 2The molar ratio of the above-mentioned preferred template agent can achieve the purpose of the present invention and synthesize a molecular sieve with adjustable positions and quantities of B and L acid sites.

[0022] In the present invention, the amount of the alkali source can be selected in a wide range. Preferably, the alkali source is OH - Calculated with silicon source (SiO 2 The molar ratio of the alkaline substance to the alkali substance is 0.1-10:1, which is specifically selected and determined according to the type of the alkaline substance.

[0023] In the present invention, in the dispersion, water and silicon source are SiO 2 Al 2 O 3 The molar ratio of the amount is relatively wide, and the commonly used amount range can achieve the purpose of the present invention. The following is an exemplary description, but it does not limit the scope of the present invention. For the present invention, it is preferred that the water, the silicon source (in the form of SiO 2 ) and aluminum source (in Al 2 O 3 The molar ratio of dosage is 10-60:1:0.001-0.1.

[0024] In the present invention, commonly used crystallization conditions can achieve the purpose of the present invention. The following is an exemplary description, but the scope of the present invention is not limited thereto. For the present invention, for example, the crystallization conditions include: a crystallization temperature of 140-220°C, preferably 150-180°C.

[0025] For example, the crystallization time is 24-96 hours, preferably 48-96 hours.

[0026] In the present invention, the silicon source, aluminum source, and alkali source can be selected from a wide range of types, and commonly used silicon sources and aluminum sources can achieve the purpose of the present invention. The following is an exemplary description, but the scope of the present invention is not limited thereby.

[0027] For example, the silicon source is selected from an organic silicon source and / or an inorganic silicon source, preferably selected from one or more of silica sol, silica gel, and organic silicone grease, more preferably tetraalkyl orthosilicate, and further preferably one or more of tetraethyl orthosilicate and tetramethyl orthosilicate.

[0028] For example, the aluminum source is selected from one or more of aluminum salts and pseudo-boehmite.

[0029] For example, the alkali source is selected from one or more of ammonium hydroxide, sodium hydroxide, potassium hydroxide, sodium carbonate, and sodium bicarbonate.

[0030] The purpose of the present invention can be achieved according to the above methods. The present invention finds that the use of silica-aluminum nanospheres as the silicon source and aluminum source for synthesizing molecular sieves is particularly suitable for application in the present invention. Preferably, the diameter of the silica-aluminum nanospheres is 400-550nm, and the Si / Al molar ratio is 100-300. For the present invention, preferably, the preparation steps of the silica-aluminum nanospheres include: dissolving an organic silicon source, a dispersant, and an alkali source in water, then adding an aluminum source to obtain a mixed solution, dispersing the mixed solution, separating the solid product of the silica-aluminum nanospheres, then washing to a pH value of less than 8, and drying the solid product.

[0031] In the present invention, the uniform dispersion can be achieved by vigorous stirring, for example, the vigorous stirring time is generally 12-48 hours. The general stirring speed can be 10-100 r / min, and 50 r / min is used as an exemplary description in the embodiment.

[0032] In the present invention, room temperature and normal temperature generally refer to indoor temperature.

[0033] In the present invention, the types of the organosilicon source, dispersant, alkali source and aluminum source can be selected from a wide range, and commonly used types can achieve the purpose of the present invention. The following is an exemplary description, but the scope of the present invention is not limited thereby.

[0034] For example, the organosilicon source is selected from organosilicon grease, preferably tetraalkyl orthosilicate, more preferably one or more of tetraethyl orthosilicate and tetramethyl orthosilicate.

[0035] For example, the dispersant is selected from one or more of ethanol, methanol, and ethylene glycol.

[0036] For example, the alkali source is selected from one or more of ammonium hydroxide, sodium hydroxide, potassium hydroxide, sodium carbonate, and sodium bicarbonate.

[0037] For example, the aluminum source is selected from one or more of aluminum salts and pseudo-boehmite.

[0038] In the present invention, the molar ratio of the dispersant, water, alkali source, organosilicon source and aluminum source can be selected in a wide range, which is exemplified below, but does not limit the scope of the present invention. For the present invention, the organosilicon source is preferably SiO 2 The alkali source is OH - The aluminum source is Al 2 O 3 In the mixed solution, the molar ratio of the dispersant, water, alkali source, organosilicon source and aluminum source is 5-160:10-60:0.1-10:1:0.001-0.1, preferably 10-80:30-50:5-10:1:0.001-0.1.

[0039] According to a particularly preferred embodiment of the present invention, the preparation steps of the silicon-aluminum nanospheres include: adding tetraethyl orthosilicate to a solution of anhydrous ethanol and ammonium hydroxide dissolved in deionized water, and then adding aluminum nitrate, the molar composition is: 5-160EtOH:10-60H 2 O:0.1-10NH 4 OH:1TEOS:0.001-0.1Al(NO 3 ) 3 .9H 2 O, preferably 10-80EtOH:30-50H 2 O:5-10NH 4 OH:1TEOS:0.001-0.1Al(NO 3 ) 3 .9H 2 O; the mixed solution is vigorously stirred at room temperature, the solid product of AS nanospheres is separated, and washed with deionized water and ethanol until the pH value of the supernatant is less than 8; the solid sample is dried overnight to obtain AS nanospheres. The above preferred implementation can achieve a more uniform morphology of AS nanospheres.

[0040] When the present invention uses silicon-aluminum nanospheres as silicon sources and aluminum sources to synthesize molecular sieves, the molecular sieve synthesis method of the present invention preferably includes: mixing and dispersing silicon-aluminum nanospheres, templates, and water to obtain an emulsion solution, and then performing the crystallization.

[0041] The synthesis method described in the present invention is particularly suitable for synthesizing silicon-aluminum molecular sieves and / or silicon-phosphorus-aluminum molecular sieves. Accordingly, the present invention provides the application of the synthesis method described in the present invention in synthesizing silicon-aluminum molecular sieves and / or silicon-phosphorus-aluminum molecular sieves, preferably in the synthesis of one or more molecular sieves selected from ZSM-5, ZSM-11, SAPO-34, MCM-22, and SAPO-11.

[0042] The present invention provides a molecular sieve synthesized by the synthesis method of the present invention, wherein the molecular sieve has a skeleton Al content of more than 90% located at the intersection of pores.

[0043] The present invention discovers for the first time that the template of the present invention can be used to synthesize molecular sieves with adjustable positions and quantities of B and L acid sites, thereby simplifying the process flow. The present invention can adjust the location of B acid at different positions without changing the Si / Al ratio while maintaining the inherent properties of the zeolite.

[0044] The molecular sieve of the present invention has a high proportion of Al located at the intersection of pores in the framework Al, and is found for the first time to be particularly suitable for methanol toluene alkylation reaction. It has the characteristics of high single-pass conversion rate, high benzene conversion rate, high selectivity for toluene and xylene, etc. when used in the reaction.

[0045] Based on this, the present invention provides the use of the molecular sieve in an alkylation reaction, and is particularly preferably used in an alkylation reaction with aromatic hydrocarbons and alcohols as raw materials, wherein the aromatic hydrocarbons are substituted or unsubstituted aromatic hydrocarbons of C6-C8, and the alcohols are C1-C3 alcohols.

[0046] In the present invention, the alkylation of benzene and methanol is used to illustrate the advantages of the present invention, but the scope of the present invention is not limited thereto. The reaction conditions of the alkylation of benzene and methanol have no special requirements. The following exemplary description is given, but the scope of the present invention is not limited thereto. Preferably, the reaction conditions of the alkylation of benzene and methanol include: a reaction temperature of 350 to 600° C., a reaction pressure of 0 to 1.0 MPa, a molar ratio of benzene to methanol of 1 to 30, and a mass space velocity of 0.1 to 30 h -1 The carrier gas that carries the reaction raw materials into the catalyst bed is an inert gas, and the carrier gas flow rate is 10-200ml / min.

[0047] The present invention will be described in detail below through examples. In the following examples, a Bruker D8 Advance diffractometer of Bruker Company was used for phase analysis, and the X-ray source was Cu Kα. The X-ray diffraction pattern was collected at a voltage of 40 kV and a current of 50 mA, with a scanning range of 2θ=5-50° and a scanning speed of 4° / min.

[0048] The scanning electron microscope images were obtained by a Zeiss Merlin scanning electron microscope (SEM) with an accelerating voltage of 20 kV.

[0049] 27 The magic angle spinning solid-state nuclear magnetic resonance spectrum of Al was collected by an Avance III 600 MHz solid-state nuclear magnetic resonance instrument, using a single pulse sequence with a pulse of 10° and a delay time of 0.3 s. 27 The chemical shifts of Al are referenced to AlCl 3 Use the Gaussian-Lorentzian equation to calibrate 27 Al MAS NMR spectra were deconvoluted.

[0050] The present invention is further described with reference to ZSM-5 molecular sieve in combination with examples, but is not limited to ZSM-5 and the present invention is not limited to the examples:

[0051] Example 1

[0052] (1) Tetraethyl orthosilicate was added to a solution of anhydrous ethanol and ammonium hydroxide dissolved in deionized water. Aluminum nitrate was then added with a molar composition of 10 EtOH: 40 H 2 O:10NH 4 OH:1TEOS:0.005Al(NO 3) 3 .9H 2 O, the mixed solution was vigorously stirred at room temperature, and the solid product of AS nanospheres was separated and washed with deionized water and ethanol until the pH value of the supernatant was less than 8. The solid sample was dried overnight to obtain AS (silicon aluminum nanospheres with a diameter of 450-550nm and a Si / Al molar ratio of 200). Figure 2 (a) is the scanning electron microscopy image of AS.

[0053] (2) Adding the AS obtained in step (1) to a solution of N,N-bis(tripropylammonium hexamethylene)-N,N-dipropylammonium bromide and deionized water, the amount of template added is the same as that of AS (in the form of SiO 2 The molar ratio of water to AS (in terms of SiO 2 Then, the alkaline source ammonium hydroxide solution was added to the above solution, NH 4 OH and AS (in the form of SiO 2 The mixture was stirred at room temperature for 2 hours to obtain an emulsion solution. The mixture was transferred to a stainless steel autoclave and crystallized at 180°C for 48 hours, washed, dried at 110°C and calcined at 550°C for 5 hours. This was designated as Cat1.

[0054] Figure 1 From the XRD characterization results of the above product, it can be seen that the product has a typical ZSM-5 molecular sieve structure and has good crystallinity.

[0055] Figure 2 (b) is the SEM image of product Cat1. The sample is composed of uniform spherical particles with a diameter of about 2 to 4 μm and a rough surface. The surface of the sample is composed of strip-shaped subcrystals with a length of 600 nm and a width of 200 nm, with a smooth surface and hard edges and corners.

[0056] Figure 3 For the above products Cat1 27 Al NMR MAS spectrum, where the peaks centered at 48, 52, and 55 ppm are attributed to the framework aluminum (Al F ), while the peaks at 57 and 60 ppm correspond to the Al in the straight and sinusoidal channels, respectively. F The specific percentage of framework aluminum at each position is shown in Table 1.

[0057] A fixed bed reactor was used, and 3 g of the formed catalyst Cat1 was loaded. At room temperature, benzene and methanol were mixed in a molar ratio of 1:1, gasified, and evenly dispersed. The mixture then entered the reactor and reacted at a temperature of 500 °C, a pressure of 0.05 MPa, and a mass space velocity of 2.0 h -1The reaction was carried out under the conditions of , the carrier gas carrying the reaction raw materials into the catalyst bed was an inert gas, and the carrier gas flow rate was 100ml / min. After the reaction, the gas product flow was obtained, which was cooled and passed into the gas-liquid separator for separation, and the liquid product was sampled and analyzed, as shown in Table 1.

[0058] Example 2

[0059] The method of Example 1 is followed, except that the materials in step (2) are fed as follows:

[0060] Add the AS obtained in step (1) to C 22 H 45 -N + (CH 3 ) 2 -C 6 H 12 -N + (CH 3 ) 2 -C 6 H 13 ](Br) 2 In the solution composed of deionized water, the amount of template added is related to AS (in the form of SiO 2 The molar ratio of water to AS (in terms of SiO 2 The molar ratio of 2-Hg (2-Hg) to 2-Hg (2-Hg) was 50, and the other conditions were the same; the molecular sieve was obtained and recorded as Cat2.

[0061] Figure 1 From the XRD characterization results of the above product, it can be seen that the product has a typical ZSM-5 molecular sieve structure and has good crystallinity.

[0062] Figure 2 (c) is the SEM image of product Cat2. The samples are uniformly composed of spherical particles with a diameter of about 2 to 4 μm and a rough surface. The surface of the sample is composed of strip-shaped subcrystals with a length of 600 nm and a width of 200 nm, with a smooth surface and hard edges and corners.

[0063] Example 3

[0064] According to the method of Example 1, the difference is that

[0065] Step (1) The materials are added as follows: tetraethyl orthosilicate is added to a solution of anhydrous ethanol and ammonium hydroxide dissolved in deionized water. Aluminum nitrate is then added with a molar composition of 80 EtOH:40 H 2 O:5NH 4 OH:1TEOS:0.005Al(NO 3 ) 3 .9H 2O, the mixed solution was vigorously stirred at room temperature, and the solid product of AS nanospheres was separated and washed with deionized water and ethanol until the pH value of the supernatant was less than 8. The solid sample was dried overnight to obtain AS (silicon aluminum nanospheres with a diameter of 450-500 nm and a Si / Al molar ratio of 200).

[0066] Step (2) feeding is as follows:

[0067] The AS obtained in step (1) is added to a solution consisting of trimer TPAOH and deionized water. The amount of template added is the same as that of AS (in the form of SiO 2 The molar ratio of water to AS (in terms of SiO 2 The molar ratio of 40 is 40, and the other conditions are the same; the molecular sieve is obtained and is recorded as Cat3.

[0068]

[0069] Figure 1 From the XRD characterization results of the above product, it can be seen that the product has a typical ZSM-5 molecular sieve structure and has good crystallinity.

[0070] Example 4

[0071] According to the method of Example 3, the difference is that

[0072] Step (2) feeding is as follows:

[0073] The AS obtained in step (1) is added to a solution of dodecyl dimethyl benzyl ammonium chloride and deionized water. The amount of template added is the same as that of AS (in the form of SiO 2 The molar ratio of water to AS (in terms of SiO 2 The molar ratio of 2-Hg (60.477 W / m) to 2-Hg (60.47 W / m) was 50, and the other conditions were the same; the molecular sieve was obtained and recorded as Cat4.

[0074] Figure 1 From the XRD characterization results of the above product, it can be seen that the product has a typical ZSM-5 molecular sieve structure and has good crystallinity.

[0075] Example 5

[0076] The method of Example 1 is followed, except that in step (1), methanol is used instead of ethanol, sodium hydroxide is used instead of ammonium hydroxide, pseudo-boehmite is used instead of aluminum nitrate, and tetramethyl orthosilicate is used instead of tetraethyl orthosilicate to obtain AS (silica-alumina nanospheres with a diameter of 450-500 nm and a Si / Al molar ratio of 200).

[0077] The other conditions are the same; the molecular sieve obtained is recorded as Cat5.

[0078] Example 6

[0079] The method of Example 1 is followed, except that in step (1), the molar composition is: 5EtOH:40H 2 O:10NH 4 OH:1TEOS:0.005Al(NO 3 ) 3 .9H 2 O, and AS (silicon aluminum nanospheres, with a diameter of 500-550 nm and a Si / Al molar ratio of 200) was obtained.

[0080] The other conditions are the same; the molecular sieve obtained is recorded as Cat6.

[0081] Example 7

[0082] The method of Example 1 is followed, except that silicon-aluminum nanospheres are not prepared, and tetraethyl orthosilicate and aluminum nitrate are used as silicon and aluminum sources. The other conditions remain unchanged, and the specific steps are as follows: first, ammonium hydroxide is added to deionized water, stirred evenly until dissolved, and recorded as solution 1; ethanol (EtOH) and N,N-bis(tripropylammonium hexamethylene)-N,N-dipropylammonium bromide are added to deionized water and stirred evenly, and added to solution 1, and then aluminum nitrate is added to the above solution, stirred and mixed to form a transparent solution. Then TEOS is added, and the resulting mixture is stirred in a sealed bottle at room temperature for 2 hours to achieve sufficient hydrolysis of TEOS, and then transferred to a stainless steel autoclave, crystallized at 180°C for 48 hours, washed, dried at 110°C, and calcined at 550°C for 5 hours. The feed composition is the same as that of Example 1 10EtOH:40H 2 O:10NH 4 OH:1TEOS:0.005Al(NO 3 ) 3 .9H 2 O, the amount of template added and the silicon source (in terms of SiO 2 The molar ratio of 2-H-2O-MnO2 to 2-H-2O-MnO2 was 0.01. The other conditions were the same; the molecular sieve was obtained and recorded as Cat7.

[0083] Example 8

[0084] According to the method of Example 1, the difference is that silicon aluminum nanospheres are not prepared, and silica sol is used as the silicon source. The other conditions remain unchanged. The specific steps are as follows: first, ammonium hydroxide is added to deionized water and stirred evenly until dissolved, which is recorded as solution 1; ethanol (EtOH) and N, N-bis (tripropylammonium hexamethylene) -N, N-dipropylammonium bromide are added to deionized water and stirred evenly, and added to solution 1, and then aluminum nitrate is added to the above solution, stirred and mixed to form a transparent solution. Then silica sol is added, and the resulting mixture is stirred in a sealed bottle at room temperature for 2h. The feed composition is the same as that of Example 1, which is 10EtOH:40H2 O:10NH 4 OH:1SiO 2 :0.005 aluminum nitrate, the amount of template added and the silicon source (in SiO 2 The molar ratio of 2-H-2O-2 was 0.01. The other conditions were the same; the molecular sieve was obtained and recorded as Cat8.

[0085] Example 9

[0086] The method of Example 1 is followed, except that the crystallization temperature is 150° C. and the crystallization time is 72 h. The other conditions remain unchanged.

[0087] The other conditions were the same; the molecular sieve obtained was recorded as Cat9.

[0088] Comparative Example 1

[0089] The method of Example 1 is followed, except that the template agent in step (2) is tetrapropylammonium hydroxide, and the other conditions remain unchanged, denoted as DCat1.

[0090] Figure 2 (d) The SEM images of the above products show that the samples are uniformly composed of spherical particles with a diameter of about 2 to 4 μm and a rough surface. The surface of the samples is composed of strip-shaped subcrystals with a length of 600 nm and a width of 200 nm, with a smooth surface and hard edges and corners.

[0091] Figure 4 Record the above products 27 Al NMR MAS spectrum, the peaks centered at 48, 52 and 55 ppm are attributed to Al in the pore intersections F , while the peaks at 57 and 60 ppm correspond to the Al in the straight and sinusoidal channels, respectively. F The specific percentages are shown in Table 1.

[0092] Comparative Example 2

[0093] The method of Example 1 is followed, except that the template agent in step (2) is tetrapropylammonium bromide, and the other conditions remain unchanged, denoted as DCat2.

[0094] Table 1

[0095]

[0096] 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 ideas disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A method for synthesizing a molecular sieve, characterized in that: The method comprises: forming a dispersion liquid with a silicon source, an aluminum source, a template agent, and an alkali source, followed by crystallization, washing, drying, and calcining; wherein the template agent is selected from N,N-bis(tripropylammonium hexamethylene)-N,N-dipropylammonium hydroxide, trimer TPA, C 22 H 45 -N(CH3)2-C6H 12 -N(CH3)2-C6H 13 ]Br2, at least one of the group consisting of tri(dodecyldimethyl-2-hydroxypropyl)-citrate triester ammonium chloride and dodecyldimethylbenzyl ammonium chloride.

2. The synthesis method according to claim 1, wherein The molar ratio of the amount of template added to the silicon source (in terms of SiO2) is 0.01-0.8; and / or in the dispersion, the molar ratio of water, silicon source (in terms of SiO2) and aluminum source (in terms of Al2O3) is 10-60:1:0.001-0.1; and / or the alkali source is OH - The molar ratio of the silicon source (in terms of SiO2) is 0.1-10:1; And / or crystallization conditions include: crystallization temperature of 140-220° C., preferably 150-180° C.; and / or crystallization time of 24-96 hours, preferably 48-96 hours.

3. The synthesis method according to claim 1 or 2, wherein The silicon source is selected from an organic silicon source and / or an inorganic silicon source, preferably selected from one or more of silica sol, silica gel, and organic silicon ester, more preferably tetraalkyl orthosilicate, and further preferably one or more of tetraethyl orthosilicate and tetramethyl orthosilicate.

4. The synthesis method according to any one of claims 1 to 3, wherein Using silicon-aluminum nanospheres as silicon and aluminum sources for synthesizing molecular sieves; Preferably, the diameter of the silicon aluminum nanospheres is 400-550 nm, and the Si / Al molar ratio is 100-300; More preferably, the preparation steps of silica-alumina nanospheres include: dissolving an organic silicon source, a dispersant, and an alkali source in water, then adding an aluminum source to obtain a mixed solution, dispersing the mixed solution, separating the solid product of silica-alumina nanospheres, then washing to a pH value less than 8, and drying the solid product.

5. The synthesis method according to claim 4, wherein The organosilicon source is selected from organosilicon esters, preferably tetraalkyl orthosilicates, more preferably one or more of tetraethyl orthosilicate and tetramethyl orthosilicate; and / or the dispersant is selected from one or more of ethanol, methanol, and ethylene glycol; and / or the alkali source is selected from one or more of ammonium hydroxide, sodium hydroxide, potassium hydroxide, sodium carbonate, and sodium bicarbonate; and / or the aluminum source is selected from one or more of aluminum salts and pseudo-boehmite; and / or The organic silicon source is calculated as SiO2, and the alkali source is calculated as OH - The aluminum source is calculated as Al2O3. In the mixed solution, the molar ratio of the dispersant, water, alkali source, organic silicon source and aluminum source is 5-160:10-60:0.1-10:1:0.001-0.1, preferably 10-80:30-50:5-10:1:0.001-0.

1.

6. The synthesis method according to claim 4 or 5, wherein The preparation steps of silica-alumina nanospheres include: adding tetraethyl orthosilicate to a solution in which anhydrous ethanol and ammonium hydroxide are dissolved in deionized water, and then adding aluminum nitrate, the molar composition of which is: 5-160EtOH:10-60H2O:0.1-10NH4OH:1TEOS:0.001-0.1Al(NO3)3.9H2O, preferably 10-80EtOH:30-50H2O:5-10NH4OH:1TEOS:0.001-0.1Al(NO3)3.9H2O; vigorously stirring the mixed solution at room temperature, separating the solid product of AS nanospheres, and washing with deionized water and ethanol until the pH value of the supernatant is less than 8; and drying the solid sample overnight to obtain AS nanospheres.

7. The synthesis method according to any one of claims 4 to 6, wherein The synthesis method of the molecular sieve comprises: mixing and dispersing silicon-aluminum nanospheres, a template agent, an alkali source and water to obtain an emulsion solution, and then performing the crystallization.

8. Use of the synthesis method according to any one of claims 1 to 7 in the synthesis of silicon-aluminum molecular sieves and / or silicon-phosphorus-aluminum molecular sieves, preferably in the synthesis of one or more molecular sieves selected from the group consisting of ZSM-5, ZSM-11, SAPO-34, MCM-22, and SAPO-11.

9. The molecular sieve synthesized by the synthesis method according to any one of claims 1 to 7, wherein the molecular sieve has a skeleton Al content of more than 90% located at the intersection of the pores.

10. Use of the molecular sieve according to claim 9 in an alkylation reaction, particularly preferably in an alkylation reaction using aromatic hydrocarbons and alcohols as raw materials, preferably, the aromatic hydrocarbons are substituted or unsubstituted aromatic hydrocarbons of C6-C8, and / or the alcohols are C1-C3 alcohols.

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