A method for producing substituted aromatic hydrocarbons by gas-phase alkylation and its catalyst

Abstract

The present invention discloses a method for producing substituted aromatics by gas-phase alkylation and its catalyst. The method uses aromatics and olefins as raw materials, and through contact reaction with the catalyst, substituted aromatics are generated. The catalyst is a silica-alumina molecular sieve catalyst, and the molecular sieve crystal inside the catalyst contains three kinds of cubic cavities with size distributions. The area distribution ranges of the rectangles corresponding to the vertical projections of these three kinds of cubic cavities from top to bottom are respectively within 20-100 nm², 200-1200 nm², and 1500-3000 nm². The method of the present invention can effectively improve the diffusion rate of reaction molecules, improve the conversion rate and the selectivity of the target product, and increase the service life of the catalyst.

Description

Technical Field

[0001] The present invention belongs to the technical fields of catalytic chemistry and chemical engineering, and particularly relates to a method for producing substituted aromatics by gas-phase alkylation. Background Art

[0002] Substituted aromatics can be obtained through the alkylation reaction of aromatics. For example, the alkylation of benzene and ethylene can obtain ethylbenzene, the alkylation of benzene and propylene can obtain cumene, the alkylation of benzene and butene can obtain butylbenzene, the alkylation of ethylbenzene and ethylene can obtain diethylbenzene or triethylbenzene, the alkylation of ethylbenzene and propylene can obtain ethylcumene, the alkylation of cumene and propylene can obtain diisopropylbenzene or triisopropylbenzene, the alkylation of toluene and ethylene can obtain methyl ethylbenzene, the alkylation of toluene and propylene can obtain methyl propylbenzene, the alkylation of ethylene and tert-butylbenzene can obtain ethyl tert-butylbenzene, the alkylation of toluene and isobutene can obtain methyl tert-butylbenzene, the alkylation of ethylbenzene and isobutene can obtain ethyl tert-butylbenzene, and so on.

[0003] Substituted aromatics are important basic organic raw materials with very wide uses and play an important role in the development of the national economy. In order to create more economic benefits, by developing an alkylation catalyst for producing aromatics that is suitable for high space velocity, the mass space velocity of olefins in the reaction process can be increased, thereby improving the operating load of the device and producing more substituted aromatics; or under the condition of the same operating load, the operating cost can be further reduced by reducing the catalyst loading amount, providing strong support for the enterprise to improve quality and increase efficiency.

[0004] Developing an alkylation catalyst for producing substituted aromatics that is suitable for high space velocity can be achieved by improving the diffusion performance of the catalyst. CN201410563714.3 discloses a MCM-22 molecular sieve with a cavity aggregation morphology and a preparation method thereof. The size of the molecular sieve is 5 - 30 μm, the cavity wall is composed of MCM-22 small crystals with a size of 20 - 200 nm, and the cavity wall thickness is 0.2 - 3.0 μm. The preparation method is as follows: (1) Mix an aluminum source, a silicon source, an alkali, water, polyethylene glycol, sodium lignosulfonate, and a template agent evenly; (2) Continue to mix the mixture under the combined action of ultrasonic dispersion and mechanical stirring; (3) Crystallize the material obtained in step (2), and the product is washed, dried, and calcined to obtain a MCM-22 molecular sieve with a cavity aggregation morphology. However, the cavity of the molecular sieve prepared by this method is not the internal cavity of the molecular sieve crystal in the true sense, but is obtained by the aggregation and piling of small crystal MCM-22 molecular sieves, belonging to the external cavity of the molecular sieve crystal. The external cavity has little effect on improving the diffusion performance inside the molecular sieve crystal, and the cavity morphology and size obtained by this method are irregular, resulting in a longer molecular diffusion path during the reaction process and the catalytic performance of the molecular sieve being correspondingly affected.

[0005] CN 201110398881.3 discloses a method for preparing hollow ZSM-5 nanozeolite, which mainly includes the following steps: mixing ZSM-5 nanozeolite with a molar ratio of silicon to aluminum of more than 20, a particle size of 100-400 nm, and monodispersed with an aqueous solution of an alkaline substance with a concentration of 0.05-0.5 mol / L, stirring at 80-200 °C for 10 h-200 h, and then separating. The ZSM-5 nanozeolite obtained by this method has fewer cavities, a single cavity size, and a relatively large single cavity size, resulting in an unsatisfactory effect on improving catalytic performance.

[0006] In summary, if through further technological innovation, cavities with specific size distributions and specific proportional combinations are prepared, the above-mentioned multiple problems can be solved simultaneously, and thus the activity, selectivity, and stability of the catalyst can be significantly improved, especially applicable to the alkylation reaction process for preparing substituted aromatics at a high space velocity. Summary of the Invention

[0007] The object of the present invention is to provide a method for gas-phase alkylation to produce substituted aromatics, so as to further improve the efficiency of gas-phase alkylation reaction, especially to improve the conversion rate of raw materials, the selectivity of products, and the stability of the catalyst.

[0008] In the first aspect of the present invention, there is provided a method for gas-phase alkylation to produce substituted aromatics, including: using aromatic hydrocarbons and olefins as raw materials, and the raw materials react with a catalyst to generate substituted aromatics; the catalyst is a silicon-aluminum molecular sieve catalyst, and the molecular sieve crystal inside the catalyst contains three types of cubic cavities with size distributions, and the area distribution ranges of the rectangles corresponding to the vertical projections of these three types of cubic cavities from top to bottom are respectively in the range of 20-100 nm 2 、200-1200 nm 2 and 1500-3000 nm 2 respectively.

[0009] In the above technical solution, preferably, the proportion of the number of the three types of cubic cavities is 40-60%, 20-30%, and 10-20% respectively.

[0010] In the above technical solution, preferably, the reaction temperature is 260-400 °C, and the reaction pressure is 0.1-3.0 MPa.

[0011] In the above technical solution, preferably, the mass space velocity of the olefin is 0.2-20.0 h -1 , and the molar ratio of aromatic hydrocarbon to olefin is 2-20.

[0012] In the above technical solution, preferably, the aromatic hydrocarbon is one or more of benzene, toluene, ethylbenzene, n-propylbenzene, isopropylbenzene, n-butylbenzene, isobutylbenzene, or tert-butylbenzene. At the above reaction temperature and pressure, the aromatic hydrocarbon is in a gaseous state.

[0013] In the above technical solution, preferably, the olefin is one or more of ethylene, propylene, n-butene, and isobutene. The olefin can be a single component, a multi-component, or other mixed gas containing the above olefins.

[0014] In the above technical solution, preferably, the produced substituted aromatic hydrocarbon is any product or its mixture formed by the reaction of the aromatic hydrocarbon and the olefin.

[0015] The second aspect of the present invention lies in providing a catalyst for gas-phase alkylation to produce substituted aromatic hydrocarbons. The catalyst is a silica-alumina molecular sieve catalyst. Inside the molecular sieve crystal of the catalyst, there are three types of cubic cavities with different size distributions. The area distribution ranges of the rectangles corresponding to the vertical projections of these three types of cubic cavities from top to bottom are respectively in the range of 20 - 100 nm 2 , 200 - 1200 nm 2 and 1500 - 3000 nm 2 .

[0016] In the above technical solution, preferably, the proportion of the number of the three types of cubic cavities is 40 - 60%, 20 - 30%, and 10 - 20% respectively.

[0017] In the above technical solution, preferably, the silica-alumina molecular sieve is an acidic molecular sieve with a ten-membered ring pore structure, and more preferably ZSM-5 molecular sieve.

[0018] In the above technical solution, preferably, the silica-alumina molecular sieve is a binderless molecular sieve.

[0019] In the above technical solution, preferably, the total specific surface area of the catalyst is 420 - 750 m 2 ·g -1 .

[0020] In the above technical solution, preferably, the total pore volume of the catalyst is 0.5 - 1.2 cm 3 ·g -1 .

[0021] In the above technical solution, preferably, the mechanical strength of the catalyst is 100 - 180 N / cm.

[0022] In the above technical solution, preferably, the bulk density of the catalyst is 0.48 - 0.58 g·cm -3 .

[0023] In the above technical solution, preferably, the molar ratio of SiO2 / Al2O3 of the catalyst is 50 - 400.

[0024] The third aspect of the present invention lies in providing a method for preparing a catalyst for gas-phase alkylation to produce substituted aromatic hydrocarbons, comprising the following steps:

[0025] (a) Calcining the shaped molecular sieve precursor D in an air atmosphere at 300 - 450 °C for 2 - 6 hours;

[0026] (b) Contacting the mixture E with a mixed organic base to obtain a mixture F, treating the mixture F at 130 - 200 °C for 4 - 24 hours, and then obtaining a benzene alkylation catalyst through washing, drying, and calcination.

[0027] In the above technical solution, preferably, in step (a), the calcination temperature and time are controlled such that the mass content of the organic matter in the mixture E is 2.0% - 5.5%. The organic matter comes from the organic template agent in the molecular sieve synthesis raw materials.

[0028] In the above technical solution, preferably, in step (b), the mixed organic base is an aqueous solution of the mixed organic base, and its mass concentration is 10% - 30%.

[0029] In the above technical solution, preferably, the mass ratio of the aqueous solution of the mixed organic base to the mixture E in step (b) is (1.5 - 25):1.

[0030] In the above technical solution, preferably, in step (b), the mixed organic base is an aqueous solution mixture of tetrapropylammonium hydroxide and at least two other quaternary ammonium bases, and the structural formula of the other quaternary ammonium bases is:

[0031]

[0032] wherein R1, R2, R3, and R4 are each independently selected from any one of n-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, benzyl, and phenethyl. R1, R2, R3, and R4 can be the same or different.

[0033] In the above technical solution, preferably, the other quaternary ammonium base contains at least three different quaternary ammonium bases.

[0034] In the above technical solution, preferably, the mass ratio of the total amount of tetrapropylammonium hydroxide to the other quaternary ammonium bases is (2 - 5):1.

[0035] In the above technical solution, preferably, the mass fraction of each quaternary ammonium base in the other quaternary ammonium bases is 20% - 60%.

[0036] In the above technical solution, preferably, the treatment process in step (b) is carried out in a closed space.

[0037] In the above technical solution, preferably, the washing, drying, and calcination in step (b) can be carried out by any conventional method. For example: washing can be carried out with deionized water until the pH value of the solution is 7 - 7.5; the drying temperature is 90 - 200 °C, and the drying time is 4 - 12 hours; the calcination temperature is 500 - 600 °C, and the calcination time is 4 - 8 hours.

[0038] In the above technical solution, preferably, the preparation process of the molecular sieve precursor in step (a) includes the following steps:

[0039] (1) Contacting a template agent, a silicon source, a first aluminum source, and water to obtain a mixture A;

[0040] Among them, the molar ratios of the template agent, the silicon source, the first aluminum source, and water are respectively: template agent:silicon source = (0.05 - 1.5):1; silicon source:first aluminum source = (50 - 400):1, water:silicon source = (5 - 20):1, where the silicon source is calculated as SiO2 and the first aluminum source is calculated as Al2O3;

[0041] (2) Contacting the mixture A, silicon powder, and a second aluminum source to obtain a mixture B;

[0042] Among them, the ratios of the mixture A, silicon powder, and the second aluminum source are respectively: the weight ratio of the mixture A to the silicon powder is (0.1 - 1.0):1; the molar ratio of the silicon powder to the second aluminum source is (50 - 400):1; where the silicon powder is calculated as SiO2 and the second aluminum source is calculated as Al2O3;

[0043] (3) Shaping the mixture B to obtain a mixture C;

[0044] (4) Contacting the mixture C and an alkali source to obtain a molecular sieve precursor D;

[0045] Among them, the weight ratio of the alkali source to the mixture C is (1.5 - 10):1.

[0046] In the above technical solution, preferably, the template agent in step (1) is a mixture of tetrapropylammonium hydroxide and tetrapropylammonium bromide, and the molar ratio of tetrapropylammonium hydroxide to tetrapropylammonium bromide is (2 - 5):1; the silicon source is one or more of silica sol, fumed silica, and tetraethyl orthosilicate; the first aluminum source is one or more of aluminum chloride, aluminum nitrate, and aluminum sulfate.

[0047] In the above technical solution, preferably, the process of obtaining the mixture A by contacting the template agent, the silicon source, the first aluminum source, and water in step (1) is: stirring the template agent, the silicon source, the first aluminum source, and water in a closed container, with a stirring time of 12h - 36h and a stirring temperature of 70 - 170 °C.

[0048] In the above technical solution, preferably, the silica powder in step (2) is silica with a size distribution of 80 - 1500 nm; the second aluminum source is one or more of aluminum chloride, aluminum nitrate, and aluminum sulfate.

[0049] In the above technical solution, preferably, in step (3), the mixture B is formed into a mixture C. The mixture C can be made into a strip shape as needed, and its cross-section is in shapes such as circular, gear-shaped, clover-shaped, four-leaf clover-shaped, or honeycomb-shaped. The diameter of the mixture C is 0.6 - 4.0 mm, and the length is 2 - 10 mm.

[0050] In the above technical solution, preferably, the base source in step (4) is one or more of ammonia water, ethylamine, ethylenediamine, n-butylamine, hexamethylenediamine, and cyclohexylamine;

[0051] In the above technical solution, preferably, the process of contacting the mixture C with the base source to obtain the molecular sieve precursor D in step (4) is: treating the mixture and the base source in a closed space at 130 - 200 °C for 24 - 120 hours. The treated product is preferably washed and dried.

[0052] The method and catalyst for gas-phase alkylation to produce substituted aromatics provided by the present invention have the following beneficial effects:

[0053] 1. Through research, it is found that the diffusion performance plays a crucial role in the gas-phase alkylation reaction for preparing substituted aromatics. For a molecular sieve catalyst, if the interior of the molecular sieve crystal contains cavities with specific sizes and proportions, it can effectively solve the problem of internal diffusion during the gas-phase alkylation reaction, improve the diffusion rate of reaction molecules, and effectively increase the conversion rate. And the generated target product can quickly diffuse out of the reaction system, inhibit the occurrence of side reactions, and improve the selectivity of the target product. At the same time, it can slow down the rate of carbon deposition formation and increase the service life of the catalyst.

[0054] 2. The catalyst of the present invention is preferably a binderless catalyst, without any inert components, completely eliminating the negative impacts of inert components on diluting the active components of the molecular sieve and blocking the micropores of the molecular sieve, and further improving the activity, selectivity, and stability of the catalyst during the alkylation reaction to produce ethylbenzene.

[0055] 3. The catalyst of the present invention has the characteristics of high specific surface area, high pore volume, high mechanical strength, and appropriate bulk density, and is particularly suitable for industrial alkylation devices for preparing substituted aromatics. Moreover, the mixed organic base used in the present invention is cheap and easily available, suitable for large-scale industrial production.

[0056] 4. The present invention is used in the gas-phase alkylation of benzene and ethylene to produce ethylbenzene. Under the reaction conditions of a relatively low molar ratio of benzene to ethylene, the conversion rate of ethylene is greater than 99.9%, the selectivity of ethyl in the alkylation product is greater than 99.8%, and the content of the key impurity xylene is below 350 ppm. Description of the Drawings

[0057] Figure 1 XRD pattern of the catalyst prepared in Example 1 of the present invention;

[0058] Figure 2 TEM photograph of the catalyst prepared in Example 1 of the present invention;

[0059] Figure 3 TEM photograph of the catalyst prepared in Comparative Example 1 of the present invention;

[0060] Figure 4 XRD pattern of the catalyst prepared in Comparative Example 2 of the present invention;

[0061] Figure 5 TEM photograph of the catalyst prepared in Comparative Example 2 of the present invention. Detailed Description of the Invention

[0062] The present invention will be described in detail below in conjunction with the specific embodiments, but it should be understood that the protection scope of the present invention is not limited by the specific embodiments.

[0063] In the present invention, the cavity size and distribution of the catalyst for gas-phase alkylation production of aromatic hydrocarbons are obtained by analyzing the TEM photographs; the total specific surface area and total pore volume are obtained by nitrogen adsorption and desorption tests; the mechanical strength is obtained by an intelligent particle strength tester; the molar ratio of SiO2 / Al2O3 is obtained by ICP test, and the organic matter content in mixture E is tested by a thermal analyzer.

[0064] In the present invention, the XRD pattern of the catalyst is obtained by using an Ultima IV type X-ray powder diffractometer produced by Rigaku Corporation of Japan. The voltage is selected as 35 kv, the current is selected as 30 mA, and the scanning speed is 1°·min -1 . During small-angle scanning, the 2θ angle is 1 - 5°, and during wide-angle scanning, the 2θ angle is 5 - 80°

[0065] In the present invention, the TEM photograph of the catalyst is obtained by using a G2F30 type transmission electron microscope produced by FEI Company of the United States. Before the test, the sample to be tested needs to be ground for 1 - 5 min, then a large amount of ethanol is added and ultrasonically dispersed evenly. The suspension is dropped on a copper mesh, and after the ethanol has completely evaporated, the test can be carried out.

[0066] In this invention, the nitrogen adsorption-desorption isotherm of the catalyst was tested at liquid nitrogen temperature using a BEL-MAX specific surface area and pore size analyzer produced by BELSORP Company of Japan. The BET equation was used to calculate the total specific surface area and total pore volume.

[0067] In this invention, the mechanical strength of the catalyst was tested using a DLIII intelligent particle strength tester developed by Dalian Penghui Science and Technology Development Co., Ltd. The length of the tested catalyst was 5 mm. It was placed horizontally on the tester to measure the maximum pressure the catalyst could withstand when crushed. After testing the crushing strength of 20 catalysts, the average value was taken.

[0068] In this invention, the bulk density of the catalyst was measured using a 1000 ml graduated cylinder as the container. It was calculated by dividing the actual weight of the added catalyst (unit: g) by the actual volume, and the unit was cm 3 ·g -1 。

[0069] In this invention, an ICP test was carried out using a Model S-35 ICP-AES analyzer of Kontron to obtain the silica-alumina ratio data.

[0070] In this invention, a TGA / DTA851 e thermal analyzer produced by Mettler-Toledo Company was used to test the organic matter content. The heating rate was 10 ℃·min -1 , the test temperature was from 25℃ to 600℃, and the protective gas was N2.

[0071]

Example 1

[0072] This example is used to synthesize a catalyst for the gas-phase alkylation production of aromatic hydrocarbons. The specific preparation process is as follows: 16.24 g of tetrapropylammonium hydroxide (aqueous solution with a concentration of 40 wt%), 5.32 g of tetrapropylammonium bromide, 208.3 g of tetraethyl orthosilicate, 4.03 g of aluminum sulfate octadecahydrate, and 90 g of water are mixed evenly, and stirred at 80 °C for 24 h in a closed container to obtain mixture A1. 24 g of mixture A1, 120 g of silicon powder, and 8.06 g of aluminum sulfate octadecahydrate are contacted to obtain mixture B1. An appropriate amount of deionized water is added to B1 and extruded into a shape to obtain mixture C1 (C1 is cylindrical, with a diameter of 0.6 mm and a length of 2 - 10 mm). 200 g of ethylenediamine and 20 g of mixture C1 are treated at 150 °C for 96 h in a closed space, then washed with deionized water until the pH value is 7.5, dried at 80 °C for 12 h to obtain mixture D1. Mixture D1 is calcined at 400 °C for 2 h in an air atmosphere, and the organic matter mass content in mixture E1 is 2.4 wt.%. 10 g of mixture E1 and 15 g of an organic base solution with a mass concentration of 30% (the solution contains three organic bases: tetrapropylammonium hydroxide, dipropyldihexylammonium hydroxide, and tributylphenylethylammonium hydroxide, and the mass ratios of the three are 67%, 19.8%, and 13.2% respectively) are mixed evenly to obtain mixture F1. Mixture F1 is treated at 150 °C for 4 h in a closed space, and then obtained the alkylation aromatic hydrocarbon production catalyst G1 through the steps of washing with deionized water until the pH value of the solution is 7, drying at 90 °C for 12 h, and calcining at 500 °C for 8 h.

[0073] The XRD pattern of the alkylation aromatic hydrocarbon production catalyst G1 is as Figure 1 shown. The diffraction peaks of the typical MFI topological structure are for the ZSM-5 molecular sieve catalyst. The TEM photo is as Figure 2 shown. There are three types of cubic cavities with different size distributions inside the molecular sieve crystals of this catalyst. The area distribution ranges of the rectangles corresponding to the vertical projections of these three types of cubic cavities from top to bottom are 35 - 75 nm 2 , 380 - 960 nm 2 and 1800 - 2900 nm 2 respectively. The proportion of the number of these three types of cubic cavities is 52%, 32%, and 16% respectively. Through testing, the total specific surface area of the alkylation aromatic hydrocarbon production catalyst G1 is 560 m 2 ·g -1 , the total pore volume is 0.8 cm 3 ·g -1 , the mechanical strength is 145 N / cm, and the bulk density is 0.52 cm 3 ·g -1 . Through ICP testing, the SiO2 / Al2O3 molar ratio of the alkylation aromatic hydrocarbon production catalyst G1 is 135.

[0074]

Example 2

[0075] This example is used to synthesize a catalyst for gas-phase alkylation to produce aromatics. The specific preparation process is as follows: 203 g of tetrapropylammonium hydroxide (aqueous solution with a concentration of 40 wt%), 133 g of tetrapropylammonium bromide, 60 g of fumed silica, 15 g of aluminum nitrate nonahydrate, and 144 g of water are mixed evenly and stirred in a closed container at 70 °C for 36 h to obtain mixture A2. 60 g of mixture A2 is contacted with 120 g of silicon powder and 30 g of aluminum nitrate nonahydrate to obtain mixture B2. An appropriate amount of deionized water is added to B2 and extruded into a shape to obtain mixture C2 (the cross-section of C2 is gear-shaped, with a diameter of 4.0 mm and a length of 2 - 10 mm). 30 g of hexamethylenediamine and 20 g of mixture C2 are treated in a closed space at 140 °C for 120 hours, then washed with deionized water until the pH value is 7.0, dried at 120 °C for 6 hours to obtain mixture D2. Mixture D2 is calcined in an air atmosphere at 300 °C for 6 hours to obtain mixture E2, and the organic matter mass content in mixture E2 is 5.2 wt.%. 10 g of mixture E2 and 250 g of an organic base solution with a mass concentration of 10% (the solution contains five organic bases: tetrapropylammonium hydroxide, tetra-n-pentylammonium hydroxide, tetra-n-hexylammonium hydroxide, n-pentyltriphenylethylammonium hydroxide, and di-n-hexyl-diphenylmethylammonium hydroxide, and the mass ratios of the five are 75%, 5%, 5%, 7.5%, and 7.5% respectively) are mixed evenly to obtain mixture F2. Mixture F2 is treated in a closed space at 200 °C for 24 hours, and then undergoes the steps of washing with deionized water until the pH value of the solution is 7.1, drying at 150 °C for 8 hours, and calcining at 550 °C for 6 hours to obtain the benzene alkylation catalyst G2.

[0076] The benzene alkylation catalyst G2 has diffraction peaks with a typical MFI topological structure and is a ZSM-5 molecular sieve catalyst. The molecular sieve crystal inside this catalyst contains three types of cubic cavities with size distributions. The area distribution ranges of the rectangles corresponding to the vertical projections of these three types of cubic cavities from top to bottom are 22 - 45 nm 2 , 300 - 600 nm 2 and 1600 - 2400 nm 2 respectively, and the proportion of the number of these three types of cubic cavities is 55%, 30%, and 15% respectively. Through testing, the total specific surface area of the benzene alkylation catalyst G2 is 440 m 2 ·g -1 , the total pore volume is 0.52 cm 3 ·g -1 , the mechanical strength is 178 N / cm, and the bulk density is 0.58 g·cm -3 . The SiO2 / Al2O3 molar ratio of the benzene alkylation catalyst G2 is obtained as 52 through ICP testing.

[0077]

Example 3

[0078] This example is used to synthesize a catalyst for gas-phase alkylation to produce aromatics. The specific preparation process is as follows: 100 g of tetrapropylammonium hydroxide (aqueous solution with a concentration of 40 wt%), 80 g of tetrapropylammonium bromide, 60 g of silica, 2.14 g of aluminum nitrate nonahydrate, and 180 g of water are mixed evenly, and stirred in a closed container at 170 °C for 12 h to obtain mixture A3. 96 g of mixture A3 is contacted with 120 g of silicon powder and 3.81 g of aluminum sulfate octadecahydrate to obtain mixture B3. An appropriate amount of deionized water is added to B3 and extruded into shape to obtain mixture C3 (the cross-section of C3 is four-leaf clover-shaped, with a diameter of 2.2 mm and a length of 3 - 8 mm). 100 g of n-butylamine and 20 g of mixture C3 are treated in a closed space at 200 °C for 24 h, then washed with deionized water until the pH value is 7.0, dried at 150 °C for 4 h to obtain mixture D3. Mixture D3 is calcined in an air atmosphere at 450 °C for 4 h to obtain mixture E3, and the organic matter mass content in mixture E3 is 2.0 wt.%. 10 g of mixture E3 and 100 g of an organic base solution with a mass concentration of 20% (the solution contains four organic bases: tetrapropylammonium hydroxide, tetra-n-butylammonium hydroxide, n-pentyltriphenylethylammonium hydroxide, and di-n-hexylbenzhydrylammonium hydroxide, and the mass ratios of the four are 80%, 10%, 6%, and 4% respectively) are mixed evenly to obtain mixture F3. Mixture F3 is treated in a closed space at 160 °C for 12 h, and then obtained the benzene alkylation catalyst G3 through the steps of washing with deionized water until the pH value of the solution is 7.3, drying at 200 °C for 4 h, and calcining at 600 °C for 4 h.

[0079] The benzene alkylation catalyst G3 has diffraction peaks with a typical MFI topological structure and is a ZSM-5 molecular sieve catalyst. The molecular sieve crystals in this catalyst contain three types of cubic cavities with size distributions. The area distribution ranges of the rectangles corresponding to the vertical projections of these three types of cubic cavities from top to bottom are 65 - 100 nm 2 、650 - 1200 nm 2 and 2600 - 3000 nm 2 respectively, and the proportion of the number of these three types of cubic cavities is 50%, 30%, and 20% respectively. Through testing, the total specific surface area of the benzene alkylation catalyst G3 is 740 m 2 ·g -1 , the total pore volume is 1.2 cm 3 ·g -1 , the mechanical strength is 115 N / cm, and the bulk density is 0.49 g·cm -3 . The SiO2 / Al2O3 molar ratio of the benzene alkylation catalyst G3 is obtained as 386 through ICP testing.

[0080]

Example 4

[0081] This example is used to synthesize a catalyst for gas-phase alkylation to produce aromatics. The specific preparation process is as follows: 120 g of tetrapropylammonium hydroxide (aqueous solution with a concentration of 40 wt%), 90 g of tetrapropylammonium bromide, 60 g of silica, 2.14 g of aluminum nitrate nonahydrate, and 180 g of water are mixed evenly, and stirred in a closed container at 120 °C for 24 h to obtain mixture A4. 96 g of mixture A4, 120 g of silicon powder, and 3.81 g of aluminum sulfate octadecahydrate are contacted to obtain mixture B4. An appropriate amount of deionized water is added to B4 and extruded into a shape to obtain mixture C4 (the cross-section of C4 is four-leaf clover-shaped, with a diameter of 2.3 mm and a length of 3 - 8 mm). 30 g of ethylenediamine and 20 g of mixture C4 are treated in a closed space at 190 °C for 24 hours, then washed with deionized water until the pH value is 7.0, dried at 150 °C for 4 hours to obtain mixture D4. Mixture D4 is calcined in an air atmosphere at 440 °C for 5 hours to obtain mixture E4, and the organic matter mass content in mixture E4 is 2.3 wt.%. 10 g of mixture E4 and 150 g of an organic base solution with a mass concentration of 20% (the solution contains four organic bases: tetrapropylammonium hydroxide, tetra-n-pentylammonium hydroxide, n-pentyltriphenylethylammonium hydroxide, and di-n-hexyl diphenylmethylammonium hydroxide, and the mass ratios of the four are 80%, 5%, 9%, and 6% respectively) are mixed evenly to obtain mixture F4. Mixture F4 is treated in a closed space at 160 °C for 24 hours, and then obtained the benzene alkylation catalyst G4 through the steps of washing with deionized water until the pH value of the solution is 7.3, drying at 200 °C for 4 hours, and calcining at 600 °C for 4 hours.

[0082] The benzene alkylation catalyst G4 has diffraction peaks with a typical MFI topological structure and is a ZSM-5 molecular sieve catalyst. There are three types of cubic cavities with different size distributions inside the molecular sieve crystals of this catalyst. The area distribution ranges of the rectangles corresponding to the vertical projections of these three types of cubic cavities from top to bottom are 35 - 85 nm 2 , 750 - 1100 nm 2 and 1600 - 2800 nm 2 respectively, and the proportion of the number of these three types of cubic cavities is 56%, 29%, and 15% respectively. Through testing, the total specific surface area of the benzene alkylation catalyst G4 is 678 m 2 ·g -1 , the total pore volume is 0.9 cm 3 ·g -1 , the mechanical strength is 145 N / cm, and the bulk density is 0.54 g·cm -3 . The SiO2 / Al2O3 molar ratio of the benzene alkylation catalyst G4 is obtained as 376 through ICP testing.

[0083]

Example 5

[0084] This example is used to synthesize a catalyst for gas-phase alkylation to produce aromatics. The specific preparation process is as follows: 135.6 g of tetrapropylammonium hydroxide (aqueous solution with a concentration of 40 wt%), 88.7 g of tetrapropylammonium bromide, 60 g of silica white, 5.7 g of aluminum nitrate nonahydrate, and 180 g of water are mixed evenly, and stirred in a closed container at 168 °C for 10 h to obtain mixture A5. 96 g of mixture A5 is contacted with 120 g of silicon powder and 10.16 g of aluminum sulfate octadecahydrate to obtain mixture B5. An appropriate amount of deionized water is added to B5 and extruded into a shape to obtain mixture C5 (the cross-section of C5 is four-leaf clover-shaped, with a diameter of 3.2 mm and a length of 3 - 8 mm). 30 g of ammonia water and 20 g of mixture C5 are treated in a closed space at 190 °C for 24 hours, and then washed with deionized water until the pH value is 7.0, dried at 150 °C for 4 hours to obtain mixture D5. Mixture D5 is calcined in an air atmosphere at 320 °C for 6 hours to obtain mixture E5, and the organic matter mass content in mixture E5 is 5.5 wt.%. 10 g of mixture E5 and 100 g of an organic base solution with a mass concentration of 30% (the solution contains four organic bases: tetrapropylammonium hydroxide, tetra-n-butylammonium hydroxide, 1-n-pentyltriphenylethylammonium hydroxide, and di-n-hexyl diphenylmethylammonium hydroxide, and the mass ratios of the four are 80%, 10%, 5%, and 5% respectively) are mixed evenly to obtain mixture F5. Mixture F5 is treated in a closed space at 180 °C for 12 hours, and then obtained the benzene alkylation catalyst G5 through the steps of washing with deionized water until the pH value of the solution is 7.3, drying at 200 °C for 4 hours, and calcining at 600 °C for 4 hours.

[0085] The benzene alkylation catalyst G5 has diffraction peaks with a typical MFI topological structure and is a ZSM-5 molecular sieve catalyst. There are three types of cubic cavities with different size distributions inside the molecular sieve crystals of this catalyst. The area distribution ranges of the rectangles corresponding to the vertical projections of these three types of cubic cavities from top to bottom are 30 - 85 nm 2 、320 - 960 nm 2 and 1600 - 2900 nm 2 respectively, and the proportion of the number of the three types of cubic cavities is 55%, 25%, and 20% respectively. Through testing, the total specific surface area of the benzene alkylation catalyst G5 is 620 m 2 ·g -1 , the total pore volume is 0.9 cm 3 ·g -1 , the mechanical strength is 168 N / cm, and the bulk density is 0.52 g·cm -3 . Through ICP testing, the SiO2 / Al2O3 molar ratio of the benzene alkylation catalyst G5 is 133.

[0086]

Example 6

[0087] This example is used to synthesize a catalyst for gas-phase alkylation to produce aromatics. The specific preparation process is as follows: 120 g of tetrapropylammonium hydroxide (aqueous solution with a concentration of 40 wt%), 85 g of tetrapropylammonium bromide, 60 g of silica white, 2.14 g of aluminum nitrate nonahydrate, and 180 g of water are mixed evenly, and stirred in a closed container at 155 °C for 10 h to obtain mixture A6. 96 g of mixture A6, 120 g of silicon powder, and 3.81 g of aluminum sulfate octadecahydrate are contacted to obtain mixture B6. An appropriate amount of deionized water is added to B6 and extruded into a shape to obtain mixture C6 (the cross-section of C6 is gear-shaped, with a diameter of 1.8 mm and a length of 3 - 8 mm). 30 g of cyclohexylamine and 20 g of mixture C6 are treated in a closed space at 195 °C for 24 h, then washed with deionized water until the pH value is 7.0, dried at 150 °C for 4 h to obtain mixture D6. Mixture D6 is calcined in an air atmosphere at 410 °C for 3 h to obtain mixture E6, and the mass content of organic matter in mixture E6 is 2.2 wt.%. 10 g of mixture E6 and 100 g of an organic base solution with a mass concentration of 20% (the solution contains four organic bases: tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, n-pentyltriphenylethylammonium hydroxide, and dihexyl diphenylmethylammonium hydroxide, and the mass ratios of the four are 80%, 10%, 5%, and 5% respectively) are mixed evenly to obtain mixture F6. Mixture F6 is treated in a closed space at 185 °C for 24 h, and then obtained the benzene alkylation catalyst G6 through the steps of washing with deionized water until the pH value of the solution is 7.3, drying at 200 °C for 4 h, and calcining at 600 °C for 4 h.

[0088] The benzene alkylation catalyst G6 has diffraction peaks with a typical MFI topological structure and is a ZSM-5 molecular sieve catalyst. There are three types of cubic cavities with different size distributions inside the molecular sieve crystals of this catalyst. The area distribution ranges of the rectangles corresponding to the vertical projections of these three types of cubic cavities from top to bottom are 40 - 90 nm 2 , 320 - 900 nm 2 and 1600 - 2600 nm 2 respectively, and the proportion of the number of these three types of cubic cavities is 52%, 30%, and 18% respectively. Through testing, the total specific surface area of the benzene alkylation catalyst G6 is 680 m 2 ·g -1 , the total pore volume is 1.1 cm 3 ·g -1 , the mechanical strength is 137 N / cm, and the bulk density is 0.53 g·cm -3 . The SiO2 / Al2O3 molar ratio of the benzene alkylation catalyst G6 obtained through ICP testing is 371.

[0089]

Comparative Example 1

[0090] Compared with Example 1, only the calcination temperature of mixture D in step (a) is different, and the rest are the same. The specific preparation process is as follows: 16.24 g of tetrapropylammonium hydroxide (aqueous solution with a concentration of 40 wt%), 5.32 g of tetrapropylammonium bromide, 208.3 g of tetraethyl orthosilicate, 4.03 g of aluminum sulfate octadecahydrate, and 90 g of water were mixed evenly, stirred at 80 °C for 24 h in a closed container to obtain mixture a1. 24 g of mixture a1 was contacted with 120 g of silicon powder and 8.06 g of aluminum sulfate octadecahydrate to obtain mixture b1. b1 was extruded into a suitable shape with deionized water to obtain mixture c1 (c1 is cylindrical, with a diameter of 0.6 mm and a length of 2 - 10 mm). 200 g of ethylenediamine and 20 g of mixture c1 were treated at 150 °C for 96 h in a closed space, then washed with deionized water until the pH value was 7.5, dried at 80 °C for 12 h to obtain mixture d1. Mixture d1 was calcined in an air atmosphere at 220 °C for 6 h to obtain mixture e1, and the organic matter content in mixture e1 was 9.8 wt.%. 10 mixture e1 and 15 g of an organic base solution with a mass concentration of 30% (the solution contains three organic bases: tetrapropylammonium hydroxide, dipropyldihexylammonium hydroxide, and tributylphenylethylammonium hydroxide, and the mass ratios of the three are 67%, 19.8%, and 13.2% respectively) were mixed evenly to obtain mixture f1. Mixture f1 was treated at 150 °C for 4 h in a closed space, and then obtained catalyst H1 through the steps of washing with deionized water until the pH value of the solution was 7, drying at 90 °C for 12 h, and calcining at 500 °C for 8 h.

[0091] The TEM photograph of catalyst H1 is as Figure 3 shown. There is no obvious cubic cavity inside the crystal of this catalyst. Through testing, the total specific surface area of catalyst H1 is 375 m 2 ·g -1 , the total pore volume is 0.41 cm 3 ·g -1 , the mechanical strength is 150 N / cm, and the bulk density is 0.59 g·cm -3 . The SiO2 / Al2O3 molar ratio of catalyst H1 obtained by ICP testing is 395.

[0092]

Comparative Example 2

[0093] Compared with Example 1, only one kind of organic base, dipropyldi-n-hexylammonium hydroxide, was added in addition to tetrapropylammonium hydroxide, and the rest was the same. The specific preparation process is as follows: 16.24 g of tetrapropylammonium hydroxide (aqueous solution with a concentration of 40 wt%), 5.32 g of tetrapropylammonium bromide, 208.3 g of tetraethyl orthosilicate, 4.03 g of aluminum sulfate octadecahydrate and 90 g of water were mixed evenly, and stirred at 80 °C for 24 h in a closed container to obtain mixture a2. 24 g of mixture a2 was contacted with 120 g of silicon powder and 8.06 g of aluminum sulfate octadecahydrate to obtain mixture b2. Mixture b2 was extruded into a suitable shape with deionized water to obtain mixture c2 (c2 was cylindrical, with a diameter of 0.6 mm and a length of 2 - 10 mm). 200 g of ethylenediamine and 20 g of mixture c2 were treated at 150 °C for 96 h in a closed space, then washed with deionized water until the pH value was 7.5, dried at 80 °C for 12 h to obtain mixture d2. Mixture d2 was calcined in an air atmosphere at 400 °C for 2 h, and the organic matter content in mixture e2 was 2.4 wt.%. 10 g of mixture e2 and 15 g of an organic base solution with a mass concentration of 30% (the solution contained two kinds of organic bases, tetrapropylammonium hydroxide and dipropyldi-n-hexylammonium hydroxide, and their mass ratios were 67% and 33% respectively) were mixed evenly to obtain mixture f2. Mixture f2 was treated at 150 °C for 4 h in a closed space, and then obtained the alkylation aromatic hydrocarbon catalyst H2 through the steps of washing with deionized water until the pH value of the solution was 7, drying at 90 °C for 12 h and calcining at 500 °C for 8 h.

[0094] The XRD pattern of catalyst H2 is as Figure 4 shown. The diffraction peaks of the typical MFI topological structure are for the ZSM-5 molecular sieve catalyst. The TEM photo of catalyst H2 is as Figure 5 shown. The area of the figure corresponding to the vertical projection of the internal cavity of the molecular sieve crystal from top to bottom and the proportion of its quantity are significantly different from the requirements of this patent. Through testing, the total specific surface area of catalyst H2 is 400 m 2 ·g -1 , the total pore volume is 1.3 cm 3 ·g -1 , the mechanical strength is 75 N / cm, and the bulk density is 0.42 cm 3 ·g -1 . The SiO2 / Al2O3 molar ratio of the catalyst was tested by ICP to be 398.

[0095]

Example 7

[0096] The catalysts prepared in the above examples and comparative examples were respectively used in the gas-phase alkylation reaction of aromatic hydrocarbons and olefins, and the reaction conditions and results are shown in Table 1.

[0097] Table 1 Gas-phase alkylation reaction conditions and results

[0098]

[0099]

Example 8

[0100] The catalysts G1 and H1 prepared in Example 1 and Comparative Example 1 were respectively tested for their single-pass lifetimes in the gas-phase alkylation of toluene and ethylene to produce ethylbenzene under ultra-high ethylene space velocity reaction conditions. The specific test conditions were as follows: the reaction temperature was 400 °C, the pressure was 1.5 MPa, the ethylene mass space velocity was 20 h -1 , the molar ratio of toluene to ethylene was 2.0. The single-pass lifetime refers to the time elapsed from the start of the reaction until the ethylene conversion rate decreased to 20%. The test results are shown in Table 2 below. Under the ultra-high ethylene space velocity reaction conditions, the single-pass lifetime of G1 was significantly longer than that of H1.

[0101] Table 2 Test results of the single-pass lifetime of the catalyst under ultra-high space velocity reaction conditions

[0102] Catalyst number Single-pass life, h G1 588 H1 340

[0103] The specific embodiments of the present invention have been described in detail above. However, the present invention is not limited thereto. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, including any other suitable combination of each technical feature. These simple modifications and combinations should also be regarded as the content disclosed by the present invention and fall within the protection scope of the present invention.

Claims

1. A method for producing substituted aromatic hydrocarbons by gas-phase alkylation, characterized in that, Using aromatic hydrocarbons and olefins as raw materials, the raw materials react with a catalyst to produce substituted aromatic hydrocarbons; the catalyst is a silica-alumina molecular sieve catalyst, and the interior of the molecular sieve crystal in the catalyst contains three types of cubic cavities with different size distributions. The area distribution ranges of the rectangles corresponding to the vertical projections of these three types of cubic cavities from top to bottom are respectively in the range of 20 - 100 nm 2 , 200 - 1200 nm 2 and 1500 - 3000 nm 2 ; the proportion of the number of these three types of cubic cavities is 40 - 60%, 20 - 30% and 10 - 20% respectively.

2. The method according to claim 1, characterized in that, The reaction temperature is 260 - 400 °C, and the reaction pressure is 0.1 - 3.0 MPa.

3. The method according to claim 1, characterized in that, The olefin mass hourly space velocity is 0.2 - 20.0 h -1 , and the molar ratio of aromatic hydrocarbons to olefins is 2 - 20.

4. The method according to claim 1, wherein The aromatic hydrocarbon is one or more of benzene, toluene, ethylbenzene, n-propylbenzene, isopropylbenzene, n-butylbenzene, isobutylbenzene, or tert-butylbenzene.

5. The method according to claim 1, wherein The olefin is one or more of ethylene, propylene, n-butene, or isobutene.

6. A catalyst for any of the methods of claims 1-5, characterized in that, The catalyst is a silica-alumina molecular sieve catalyst. Inside the molecular sieve crystals of the catalyst, there are three types of cubic cavities with different size distributions. The area distribution ranges of the rectangles corresponding to the vertical projections of these three types of cubic cavities from top to bottom are respectively in the range of 20 - 100 nm 2 , 200 - 1200 nm 2 and 1500 - 3000 nm 2 ; The proportion of the number of the three types of cubic cavities is 40 - 60%, 20 - 30% and 10 - 20% respectively.

7. The catalyst according to claim 6, characterized in that, The silica-alumina molecular sieve is a binderless molecular sieve.

8. The catalyst according to claim 6, characterized in that The total specific surface area of the catalyst is 420 - 750 m 2 ·g -1 ; the total pore volume of the catalyst is 0.5 - 1.2 cm 3 ·g -1 .

9. The catalyst according to claim 6, characterized in that, The mechanical strength of the catalyst is 100 - 180 N / cm; the bulk density of the catalyst is 0.48 - 0.58 g·cm -3 .

10. A catalyst for any of the methods of claims 1 - 5 or a preparation method of the catalyst according to any of claims 6 - 9, comprising the following steps: (a) Calcining the shaped molecular sieve precursor D in an air atmosphere at 300 - 450 °C for 2 - 6 hours to obtain a mixture E; (b) Contacting the mixture E with a mixed organic base to obtain a mixture F, treating the mixture F at 130 - 200 °C for 4 - 24 hours, and then obtaining a benzene alkylation catalyst through washing, drying, and calcining; In step (b), the mixed organic base is an aqueous solution mixture of tetrapropylammonium hydroxide and at least two other quaternary ammonium bases, and the structural formula of the other quaternary ammonium bases is: ， where R1, R2, R3, and R4 are each independently selected from any one of n-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, benzyl, and phenethyl.

11. The preparation method according to claim 10, characterized in that, In step (a), the calcination temperature and time are controlled such that the mass content of the organic matter in the mixture E is 2.0% - 5.5%.

12. The preparation method according to claim 10, characterized in that, In step (b), the mixed organic base is an aqueous solution of the mixed organic base, and its mass concentration is 10% - 30%; the mass ratio of the aqueous solution of the mixed organic base to the mixture E is (1.5 - 25):1.

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