Benzene and methanol reaction method

Abstract

The invention discloses a benzene and methanol reaction method, in the presence of a ZSM-5 molecular sieve, benzene and methanol are contacted, and the ratio of the ZSM-5 molecular sieve and a skeleton Al located at the cross point of pore channels is more than 80%, preferably more than 90%. The method has the characteristics of high conversion per pass, high conversion rate of benzene, high selectivity of toluene and xylene and the like.

Description

Technical Field

[0001] The invention relates to a method for reacting benzene and methanol. Background Art

[0002] Paraxylene (PX) is an important organic chemical raw material, mainly used to prepare para-toluenedicarboxylic acid (PTA), and then to produce polyethylene terephthalate (PET). It can also be used as a solvent and a raw material for the production of medicine, fragrance, ink and other industries. It has a wide range of uses. With the increase in my country's polyester production capacity, the demand for PX continues to increase. The main technologies for preparing PX in industry include xylene disproportionation and alkylation, xylene methanol alkylation, xylene isomerization and xylene adsorption separation. With the expansion of the scale of my country's reforming units and the increase in ethylene production, the production capacity of pure toluene continues to increase. The alkylation reaction of toluene with cheap methanol not only expands the downstream utilization of toluene, but also produces high value-added paraxylene.

[0003] At present, the catalysts used in the alkylation of toluene and methanol are mainly molecular sieve catalysts. Molecular sieves have the advantages of unique pore structure, rich acid types and stable crystal skeleton structure, making them the star catalysts in the alkylation of toluene and methanol. The alkylation of toluene and methanol is a B acid catalyzed reaction, so the acidic properties of molecular sieves, including distribution, type and density, are very important. At present, the acidity regulation of molecular sieves is mainly achieved by loading metal / non-metal active components, co-catalyst components and post-treatment of molecular sieves.

[0004] CN102114429A discloses a method for metal modification of ZSM-5 molecular sieve to increase the B acid content in the molecular sieve, which is used in catalytic cracking reactions of long-chain alkanes. It is found that the method not only has high catalytic activity but also improves the yield of low-carbon olefins.

[0005] CN 1931432A discloses a method of using a rapid ion exchange method + impregnation method to simultaneously introduce at least two alkaline earth metals into a powdered hydrogen-type ZSM-5 series molecular sieve, thereby obtaining an alkaline earth metal-modified ZSM series molecular sieve with uniform performance. The obtained molecular sieve catalyst contains an increased amount of weak acid and L acid, and is applied to the catalytic cracking reaction of petroleum hydrocarbons, ultimately obtaining a higher olefin yield.

[0006] From the above reports, it can be found that among the current methods for regulating the microscopic aluminum distribution of molecular sieves, the application of designing structure-directing agents to control the microscopic aluminum distribution of ZSM5 molecular sieves in one step during the synthesis process in the reaction of toluene and methanol has not been reported. Summary of the invention

[0007] The object of the present invention is to provide a method for reacting benzene and methanol with high single-pass conversion rate and good target product selectivity.

[0008] The present invention provides a method for reacting benzene and methanol. Benzene and methanol are contacted in the presence of a ZSM-5 molecular sieve, wherein the ZSM-5 molecular sieve has a skeleton Al content at the intersection of pores greater than 80%, preferably greater than 90%.

[0009] In the present invention, the ZSM-5 molecular sieve of the present invention is mainly used. There is no special requirement for the reaction conditions of the reaction of benzene and methanol. The following exemplary description is given, but the scope of the present invention is not limited thereto. Preferably, the reaction conditions of the reaction of benzene and methanol include: a reaction temperature of 350 to 600°C, for example, 350°C, 400°C, 450°C, 500°C, 550°C, and 600°C. In the embodiments, 500°C is used as an example to illustrate the advantages of the present invention, but the scope of the present invention cannot be limited thereto.

[0010] In the present invention, the reaction pressure is adjusted according to actual needs, for example, the reaction pressure is 0-1.0 MPa, for example, 0.01 MPa, 0.05 MPa, 0.1 MPa, 0.5 MPa, etc. In the embodiments of the present invention, 0.05 MPa is used as an example to illustrate the advantages of the present invention, but the scope of the present invention cannot be limited thereby.

[0011] In the present invention, the molar ratio of benzene to methanol can be selected in a wide range, for example, 1 to 30, such as 1, 5, 10, 15, 20, 25, 30. In the embodiments of the present invention, 1 is used as an example to illustrate the advantages of the present invention, but the scope of the present invention cannot be limited thereby.

[0012] In the present invention, the reaction mass space velocity is 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.

[0013] The ZSM-5 molecular sieve having the aforementioned characteristics of the present invention can achieve the purpose of the present invention, and there is no special requirement for its preparation method. The following exemplifies an implementation method, but does not limit the scope of the present invention.

[0014] According to one embodiment of the present invention, the preparation method of ZSM-5 molecular sieve comprises: forming a dispersion liquid with a silicon source, an aluminum source, a structure directing agent, and an alkali source, followed by crystallization, washing, drying, and calcining; wherein the structure directing 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)-C6H 13]Br2, at least one of the group consisting of tri(dodecyldimethyl-2-hydroxypropyl)-tris(citrate)ammonium chloride (CTTAC) and dodecyldimethylbenzylammonium chloride. This can further improve the conversion rate of benzene and the selectivity of toluene and xylene.

[0015] The present invention discovers for the first time that the structure directing agent of the present invention can be used to synthesize molecular sieves with adjustable positions and quantities of B and L acidic sites, 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.

[0016] 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.

[0017] For example, the crystallization time is 24-96 hours, preferably 48-96 hours.

[0018] 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.

[0019] 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.

[0020] For example, the aluminum source is selected from one or more of aluminum salts and pseudo-boehmite.

[0021] For example, the alkali source is selected from one or more of ammonium hydroxide, sodium hydroxide, potassium hydroxide, sodium carbonate, and sodium bicarbonate.

[0022] During the specific operation, various materials can be added according to the actual situation. For example, 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 to obtain an emulsion solution, followed by the crystallization, washing, drying and calcining.

[0023] In the present invention, the amount of the structure directing agent can be selected in a wide range, and the purpose is to adjust the B acid position, so the amount is generally: the molar ratio of the amount of the structure directing agent added to the silicon source (in terms of SiO2) is 0.01-0.8. The use of the above-mentioned preferred amount of the structure directing agent can achieve the purpose of the present invention, and can synthesize a molecular sieve with adjustable positions and quantities of B and L acid sites. This can further improve the conversion rate of benzene and the selectivity of toluene and xylene.

[0024] In the present invention, the amount of the alkali source can be selected in a wide range. Preferably, the molar ratio of the alkali source (in terms of OH-) to the silicon source (in terms of SiO2) is 0.1-10:1, which is specifically selected and determined according to the type of alkaline substance.

[0025] In the present invention, the molar ratio of water, silicon source (in terms of SiO2) and aluminum source (in terms of Al2O3) in the dispersion can be selected in a wide range, and the commonly used dosage range can achieve the purpose of the present invention. The following exemplary description is not intended to limit the scope of the present invention. For the present invention, the molar ratio of water, silicon source (in terms of SiO2) and aluminum source (in terms of Al2O3) in the dispersion is preferably 10-60:1:0.001-0.1. This can further improve the conversion rate of benzene and the selectivity of toluene and xylene.

[0026] The object of the present invention can be achieved by the above methods. The present invention finds that the use of silicon-aluminum nanospheres as the silicon source and aluminum source for synthesizing molecular sieves is particularly suitable for application in the present invention. For the present invention, preferably, the diameter of the silicon-aluminum nanospheres is 450-550nm, and the Si / Al molar ratio is 100-300. This can further improve the conversion rate of benzene and the selectivity of toluene and xylene.

[0027] 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, a structure directing agent, an alkali source, and water to obtain an emulsion solution, and then performing the crystallization.

[0028] All silicon-aluminum nanospheres with the above characteristics can be used in the present invention without any special requirements for their preparation methods. According to one embodiment of the present invention, preferably, the preparation steps of silicon-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 a solid product of silicon-aluminum nanospheres, then washing to a pH value of less than 8, and drying the solid product. This can further improve the conversion rate of benzene and the selectivity of toluene and xylene.

[0029] 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.

[0030] In the present invention, room temperature and normal temperature generally refer to indoor temperature.

[0031] 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.

[0032] For example, the organosilicon source is selected from organosilicon greases, preferably tetraalkyl orthosilicates, more preferably one or more of tetraethyl orthosilicate and tetramethyl orthosilicate.

[0033] For example, the dispersant is selected from one or more of ethanol, methanol, and ethylene glycol.

[0034] For example, the alkali source is selected from one or more of ammonium hydroxide, sodium hydroxide, potassium hydroxide, sodium carbonate, and sodium bicarbonate.

[0035] For example, the aluminum source is selected from one or more of aluminum salts and pseudo-boehmite.

[0036] In the present invention, the molar ratio of the amount of dispersant, water, alkali source, organosilicon source, and aluminum source can be selected in a wide range. The following exemplary description is provided, but the scope of the present invention is not limited thereto. For the present invention, preferably the organosilicon source is calculated as SiO2, the alkali source is calculated as OH-, and the aluminum source is calculated as Al2O3. In the mixed solution, the molar ratio of the amount of 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. This can further improve the conversion rate of benzene and the selectivity of toluene and xylene.

[0037] According to a particularly preferred embodiment of the present invention, the preparation steps of 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: 10-60H2O: 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, 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. The aforementioned preferred embodiment can achieve a more uniform morphology of AS nanospheres. This can further improve the conversion rate of benzene and the selectivity of toluene and xylene.

[0038] The present invention discovers for the first time that the structure directing agent of the present invention can be used to synthesize molecular sieves with adjustable positions and quantities of B and L acidic sites, 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.

[0039] 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 the reaction of methanol and toluene. It has the characteristics of high single-pass conversion rate, high benzene conversion rate, high selectivity for toluene and xylene, etc.

[0040] The method of the invention has the characteristics of high single-pass conversion rate, high benzene conversion rate, high selectivity of toluene and xylene, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 Shown is the XRD spectrum of the molecular sieve prepared in Examples 1-4 of the present invention;

[0042] 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;

[0043] 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

[0044] 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.

[0045] 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.

[0046] The scanning electron microscope images were obtained by a Zeiss Merlin scanning electron microscope (SEM) with an accelerating voltage of 20 kV.

[0047] 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 shift of Al was calibrated with reference to AlCl3. 27 Al MAS NMR spectra were deconvoluted.

[0048] 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:

[0049] Example 1

[0050] (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 10EtOH:40H2O:10NH4OH:1TEOS:0.005Al(NO3)3.9H2O. 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.

[0051] (2) The AS obtained in step (1) is added to a solution formed by N,N-bis(tripropylammonium hexamethylene)-N,N-dipropylammonium bromide and deionized water, the molar ratio of the added amount of the structure directing agent to AS (calculated as SiO2) is 0.01; the molar ratio of water to AS (calculated as SiO2) is 30; then the alkaline source ammonium hydroxide solution is added to the above solution, the molar ratio of NH4OH to AS (calculated as SiO2) is 10, and then the resulting mixture is continuously stirred at room temperature for 2 hours to obtain an emulsion solution. Transfer to a stainless steel autoclave, crystallize at 180°C for 48 hours, wash, dry at 110°C and calcine at 550°C for 5 hours. Recorded as Cat1.

[0052] 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.

[0053] 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.

[0054] 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.

[0055] 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 -1 The 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.

[0056] Example 2

[0057] The method of Example 1 is followed, except that the materials in step (2) are fed as follows:

[0058] Add the AS obtained in step (1) to C 22 H 45 -N + (CH3)2-C6H 12 -N + (CH3)2-C6H 13 ](Br)2 and deionized water, the molar ratio of the added amount of the structure directing agent to AS (calculated as SiO2) is 0.5; the molar ratio of water to AS (calculated as SiO2) is 50, and the other conditions are the same; the molecular sieve is obtained, which is recorded as Cat2.

[0059] 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.

[0060] 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.

[0061] Example 3

[0062] According to the method of Example 1, the difference is that

[0063] 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 80EtOH:40H2O:5NH4OH:1TEOS:0.005Al(NO3)3.9H2O, and the mixed solution is vigorously stirred at room temperature to separate the solid product of AS nanospheres, which is 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 (silicon aluminum nanospheres with a diameter of 450-500nm and a Si / Al molar ratio of 200).

[0064] Step (2) feeding is as follows:

[0065] The AS obtained in step (1) is added to a solution consisting of trimer TPAOH and deionized water, the molar ratio of the added structure directing agent to AS (calculated as SiO2) is 0.3; the molar ratio of water to AS (calculated as SiO2) is 40, and the other conditions are the same; a molecular sieve is obtained, which is recorded as Cat3.

[0066] Trimeric TPAOH

[0067] 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.

[0068] Example 4

[0069] According to the method of Example 3, the difference is that

[0070] Step (2) feeding is as follows:

[0071] The AS obtained in step (1) is added to a solution consisting of dodecyldimethylbenzylammonium chloride and deionized water, the molar ratio of the added amount of the structure directing agent to AS (calculated as SiO2) is 0.4; the molar ratio of water to AS (calculated as SiO2) is 50, and the other conditions are the same; a molecular sieve is obtained, which is recorded as Cat4.

[0072] Figure 1From 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.

[0073] Example 5

[0074] 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).

[0075] The other conditions are the same; the molecular sieve obtained is recorded as Cat5.

[0076] Example 6

[0077] The method of Example 1 is followed, except that in step (1), the molar composition is: 5EtOH:40H2O:10NH4OH:1TEOS:0.005Al(NO3)3.9H2O, to obtain AS (silicon aluminum nanospheres, with a diameter of 500-550 and a Si / Al molar ratio of 200).

[0078] The other conditions are the same; the molecular sieve obtained is recorded as Cat6.

[0079] Example 7

[0080] According to the method of Example 1, the difference is that silicon-aluminum nanospheres are not prepared, tetraethyl orthosilicate and aluminum nitrate are used as silicon source and aluminum source, and the other conditions remain unchanged. 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 in Example 1: 10EtOH: 40H2O: 10NH4OH: 1TEOS: 0.005Al(NO3)3.9H2O, and the molar ratio of the added amount of the structure directing agent to the silicon source (in terms of SiO2) is 0.01. The other conditions are the same; a molecular sieve is obtained, which is recorded as Cat7.

[0081] Example 8

[0082] 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, 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, 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: 40H2O: 10NH4OH: 1SiO2: 0.005 aluminum nitrate, and the molar ratio of the amount of structure directing agent added to the silicon source (in terms of SiO2) is 0.01. The other conditions are the same; a molecular sieve is obtained, recorded as Cat8.

[0083] Example 9

[0084] 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.

[0085] The other conditions were the same; the molecular sieve obtained was recorded as Cat9.

[0086] Comparative Example 1

[0087] 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.

[0088] 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.

[0089] 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.

[0090] Comparative Example 2

[0091] 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.

[0092] Table 1

[0093]

[0094] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

[0095] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A method for reacting benzene and methanol, characterized in that: Benzene is contacted with methanol in the presence of a ZSM-5 molecular sieve, wherein the ZSM-5 molecular sieve has a skeleton Al content located at the intersection of pores greater than 80%, preferably greater than 90%.

2. The method according to claim 1, wherein: Conditions of exposure include: The reaction temperature is 350-600°C, the reaction pressure is 0-1.0 MPa, the molar ratio of benzene to methanol is 1-30, and the mass space velocity is 0.1-30 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.

3. The method according to claim 1 or 2, wherein: The preparation method of the ZSM-5 molecular sieve comprises: forming a dispersion liquid with a silicon source, an aluminum source, a structure directing agent, and an alkali source, followed by crystallization, washing, drying, and calcining; wherein the structure directing agent is selected from N,N-bis(tripropylammoniumhexamethylene)-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.

4. The method according to claim 3, wherein: The molar ratio of the amount of the structure directing agent 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.

5. The method according to claim 3 or 4, wherein: The crystallization conditions include: a crystallization temperature of 140-220° C., preferably 150-180° C.; and / or a crystallization time of 24-96 hours, preferably 48-96 hours.

6. The method according to any one of claims 3 to 5, 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.

7. The method according to claim 3 or 4, wherein: Using silicon-aluminum nanospheres as silicon and aluminum sources for synthesizing molecular sieves; Preferably, the synthesis method of the molecular sieve comprises: mixing and dispersing silicon-aluminum nanospheres, a structure directing agent, an alkali source, and water to obtain an emulsion solution, and then performing the crystallization; Preferably, the diameter of the silicon aluminum nanospheres is 450-550 nm, and the Si / Al molar ratio is 100-300; 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.

8. The method according to claim 7, wherein: In the preparation of silica-alumina nanospheres, the organic silicon source is selected from organic silicon 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.

9. The method according to claim 7 or 8, wherein: In the preparation of silicon-aluminum nanospheres, 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.

10. The method according to claim 7, 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.

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