A ZSM-5 molecular sieve, its preparation and application

Abstract

This invention discloses a ZSM-5 molecular sieve, its preparation, and its application. The preparation method of the molecular sieve includes: (a) mixing silicon source I, aluminum source I, water, template agent I, and organic compound I, and processing the mixture to obtain mixture A; (b) mixing mixture A, silicon source II, aluminum source II, water, template agent II, and organic compound II to obtain mixture B; (c) crystallizing mixture B, followed by liquid-solid separation, washing, and drying to obtain the molecular sieve; wherein, organic compound I is a silane containing aminopropyl groups. The molecular sieve, when formulated as a catalyst, is particularly suitable for the alkylation of benzene and ethylene to ethylbenzene, exhibiting high ethyl selectivity in the alkylation product and low content of the key impurity xylene.

Description

Technical Field

[0001] This invention belongs to the technical field of catalytic chemistry and chemical engineering, and in particular relates to a ZSM-5 molecular sieve and its preparation and application. Background Technology

[0002] Ethylbenzene is an important organic chemical raw material. Its downstream applications are mainly in the production of styrene, which is then used to synthesize resins and plastics and other polymer materials. It is widely used in automobiles, electronics, aviation, urban construction and daily necessities, and is of great significance to the development of the national economy.

[0003] Ethylbenzene is generally produced by alkylation of benzene and ethylene under the catalysis of acidic molecular sieves. The sources of ethylene are diverse, including pure ethylene, dilute ethylene, and ethanol. Using dilute ethylene as a raw material offers a significant cost advantage, generating greater economic benefits for enterprises. Dilute ethylene typically originates from the tail gas of FCC and DCC units, or from the cracking of crude ethane, with an ethylene concentration generally ranging from 10-70 wt%. Dilute ethylene has a complex composition, containing not only alkanes, nitrogen, or hydrogen that do not participate in the alkylation reaction, but also propylene, butene, or other olefins that can react with benzene. The presence of these impurities in the raw material leads to increased side reactions during the reaction, decreased ethyl selectivity in the alkylation product, and increased content of xylene, a key impurity that is difficult to separate, severely impacting the quality of the ethylbenzene product.

[0004] CN1310048A discloses a method for improving the selectivity and stability of zeolite catalysts for ethylbenzene production. This method prepares the catalyst by modifying the outer surface of ZSM-5 zeolite containing an organic amine (templating agent) with an organic acid. When the catalyst obtained by this method is used for the alkylation of benzene and ethylene to produce ethylbenzene, the ethyl selectivity is only 97.5% at an ethylene conversion rate of 95%, and the xylene content in the product is still as high as 1000 ppm. Therefore, this catalyst still suffers from low ethyl selectivity and a high content of the key impurity xylene. Summary of the Invention

[0005] This invention provides a ZSM-5 molecular sieve, a catalyst for the alkylation of benzene to ethylbenzene, and their preparation and application. The ZSM-5 molecular sieve of this invention is a novel type. The catalyst prepared using the molecular sieve of this invention, when used in the gas-phase alkylation of benzene and ethylene to ethylbenzene, can effectively improve the ethyl selectivity in the alkylation product, suppress side reactions, and reduce the xylene content.

[0006] The first aspect of this invention provides a method for preparing ZSM-5 molecular sieve, comprising:

[0007] (a) Silicon source I, aluminum source I, water, template agent I and organic matter I are mixed and processed to obtain mixture A;

[0008] (b) Mix mixture A, silicon source II, aluminum source II, water, template agent II and organic matter II to obtain mixture B;

[0009] (c) After crystallization, mixture B is subjected to liquid-solid separation, washing, and drying to obtain the molecular sieve;

[0010] In step (a), organic compound I is a silane containing aminopropyl, preferably one or more of N-aminoethyl-3-aminopropylmethyldimethoxysilane, N-(n-butyl)-3-aminopropyltrimethoxysilane or N-(2-aminoethyl)-3-aminopropyltriethoxysilane.

[0011] In the above technical solution, preferably, step (a) has one or more of the following features:

[0012] In the above technical solution, preferably, the silicon source I in step (a) is one or more of tetraethyl silicate, tetrapropyl silicate, and tetrabutyl silicate;

[0013] In the above technical solution, preferably, in step (a), aluminum source I is one or more of aluminum sulfate, aluminum isopropoxide, sodium aluminate, and boehmite;

[0014] In the above technical solution, preferably, in step (a), template agent I is one or more of tetrapropylammonium hydroxide, ethylamine, ethylenediamine, n-butylamine, butanediamine, hexamethyleneimine, piperidine, piperazine, and homopiperazine;

[0015] In the above technical solution, preferably, the molar ratios of silicon source I, aluminum source I, water, template agent I and organic matter I in step (a) are as follows: silicon source I: aluminum source I: water: template agent I: organic matter I = 1:(0.002-0.02):(5-20):(0.1-0.5):(0.02-0.2), wherein silicon source I and aluminum source I are calculated as SiO2 and Al2O3, respectively.

[0016] In the above technical solution, preferably, the processing conditions in step (a) are: stirring at 50-80°C for 5-30 hours under sealed conditions.

[0017] In the above technical solution, preferably, step (b) has one or more of the following features:

[0018] In the above technical solution, preferably, the silicon source II in step (b) is one or more of silica sol, silica fume, silica powder, tetramethyl silicate, tetraethyl silicate, tetrapropyl silicate, and tetrabutyl silicate.

[0019] In the above technical solution, preferably, the aluminum source II in step (b) is one or more of aluminum nitrate, aluminum chloride, aluminum sulfate, aluminum isopropoxide, sodium aluminate, and boehmite;

[0020] In the above technical solution, preferably, in step (b), template agent II is one or more of tetrapropylammonium bromide, tetrapropylammonium hydroxide, ethylamine, ethylenediamine, n-propylamine, propylenediamine, n-butylamine, butylenediamine, n-hexylamine, hexamethylenediamine, ammonia, hexamethyleneimine, piperidine, piperazine, and hyperpiperazine;

[0021] In the above technical solution, preferably, in step (b), organic compound II is a phenyl-containing disilazine, preferably one or more of 1,3-diphenyltetramethyldisilazine, 1,3-dichloro-1,1,3,3-tetraphenyldisilazine or 1,3-diphenyltetraethyldisilazine.

[0022] In the above technical solution, preferably, the molar ratios of silicon source II, aluminum source II, water, template agent II, and organic matter II in step (b) are as follows: silicon source II: aluminum source II: water: template agent II: organic matter II = 1:(0.002-0.02):(10-25):(0.1-0.4):(0.005-0.15), and the ratio of the mass of the mixture A to the total mass of the five substances silicon source II, aluminum source II, water, template agent II, and organic matter II is (0.04-0.22):1, wherein silicon source II and aluminum source II are calculated as SiO2 and Al2O3, respectively.

[0023] In the above technical solution, preferably, the crystallization conditions in step (c) are crystallization at 130-180°C for 10-60 hours under sealed conditions.

[0024] In the above technical solution, preferably, the liquid-solid separation method in step (c) is filter paper filtration, centrifugation, or plate and frame filtration; the washing conditions are to wash the solid obtained from the liquid-solid separation multiple times with deionized water until the pH value of the washing liquid is 7-8. The drying conditions are drying at 100-200℃ for 5-12 hours.

[0025] The second aspect of the present invention provides a ZSM-5 molecular sieve prepared by the method of the first aspect.

[0026] In the above technical solution, the infrared spectrum of the molecular sieve is in the wavenumber range of 680-760 cm⁻¹. -1 Two strong peaks appeared at the location.

[0027] In the above technical solution, preferably, the thickness of the b-axis of the molecular sieve is 20-120 nm, more preferably 30-100 nm, and the exposure of the crystal plane perpendicular to the b-axis is 65%-80%, more preferably 65%-75%.

[0028] In the above technical solution, preferably, the SiO2 / Al2O3 molar ratio of the molecular sieve is 50-500.

[0029] A third aspect of the present invention provides a catalyst for the alkylation of benzene to ethylbenzene, the catalyst comprising ZSM-5 molecular sieve, wherein the synthesized state of the ZSM-5 molecular sieve is the molecular sieve prepared by the method of the first aspect.

[0030] In the above technical solution, the ZSM-5 molecular sieve in the catalyst exists in a calcined state.

[0031] In the above technical solution, the catalyst may optionally include alumina, silicon dioxide, or a mixture thereof, in addition to molecular sieves.

[0032] In the above technical solution, preferably, the catalyst, based on the mass of the catalyst, has a molecular sieve content of 80% or more, preferably 80%-90%, and an alumina content of 20% or less, preferably 10%-20%.

[0033] In the above technical solution, preferably, the micropore volume of the catalyst is 0.11-0.16 cm³. 3 ·g -1 The mesopore volume is 0.40-0.80 cm³. 3 ·g -1 Its mechanical strength is 60-120 N / cm, and its bulk density is 0.50-0.60 g·cm³. -3 .

[0034] A fourth aspect of this invention provides a method for preparing a catalyst for the alkylation of benzene to ethylbenzene, comprising:

[0035] (d) The ZSM-5 molecular sieve, alumina and polymer mixture prepared by the method in the first aspect are mixed and shaped, and then dried, calcined, subjected to ammonium exchange, steam treatment and acid washing to obtain the catalyst.

[0036] In the above technical solution, preferably, step (d) has one or more of the following features:

[0037] In the above technical solution, preferably, the alumina in step (d) is alumina monohydrate;

[0038] In the above technical solution, preferably, the polymer mixture in step (d) is a mixture of starch and hexadecyltrimethylammonium bromide, wherein the mass ratio of starch to polymer mixture is 30%-50%;

[0039] In the above technical solution, preferably, the mass ratio of molecular sieve, alumina and polymer mixture in step (d) is: molecular sieve: alumina: polymer mixture = 1:(0.05-0.2):(0.05-0.1);

[0040] In the above technical solution, preferably, a molding aid, such as at least one of dilute nitric acid and guar gum powder, can be added in step (d).

[0041] In the above technical solution, preferably, the dilute nitric acid in step (d) is an aqueous solution of nitric acid with a mass concentration of 1%-5%;

[0042] In the above technical solution, preferably, the mass ratio of molecular sieve, dilute nitric acid, and guar gum powder in step (d) is: molecular sieve: dilute nitric acid: guar gum powder = 1:(0.8-1.0):(0.03-0.05);

[0043] In the above technical solution, preferably, the molding in step (d) is extrusion molding, followed by drying, calcination, ammonium exchange, steam treatment, and acid washing.

[0044] In the above technical solution, preferably, the molding shape in step (d) is cylindrical, clover-shaped, four-leaf clover-shaped, gear-shaped, etc.; the drying conditions are 100-150℃ for 10-15 hours; the calcination conditions are 400-550℃ for 4-10 hours; the ammonium exchange conditions are 1%-5% ammonium salt solution at 10-70℃ for 2-5 hours, with 2-5 consecutive exchanges, and the ammonium salt is one of ammonium sulfate, ammonium chloride, ammonium acetate, or ammonium nitrate; the steam treatment conditions are 400-500℃ for 3-8 hours in a saturated steam atmosphere; the pickling conditions are 0.5%-2.0% acid solution at 10-90℃ for 2-8 hours, and the acid is at least one of hydrochloric acid, sulfuric acid, nitric acid, or oxalic acid.

[0045] The fifth aspect of the present invention provides a catalyst for the alkylation of benzene to ethylbenzene prepared by the method of the fourth aspect.

[0046] In the above technical solution, preferably, the molecular sieve catalyst, based on the mass of the catalyst, has a molecular sieve content of 80% or more, preferably 80%-90%, and an alumina content of 20% or less, preferably 10%-20%.

[0047] In the above technical solution, preferably, the micropore volume of the catalyst is 0.11-0.16 cm³. 3 ·g -1 The mesopore volume is 0.40-0.80 cm³. 3 ·g -1 Its mechanical strength is 60-120 N / cm, and its bulk density is 0.50-0.60 g·cm³.-3 .

[0048] The sixth aspect of the present invention provides a method for producing ethylbenzene by benzene alkylation, wherein the reaction raw materials benzene and ethylene are contacted with the above-mentioned catalyst to generate ethylbenzene.

[0049] In the above technical solution, preferably, the ethylene mass concentration in the ethylene feedstock is 10%-100%.

[0050] In the above technical solution, preferably, the reaction temperature is 300-380℃, the reaction pressure is 0.4-2.5MPa, and the ethylene mass hourly space velocity is 0.1-3.0h. -1 The molar ratio of benzene to ethylene is 4.0-6.0.

[0051] Compared with the prior art, the present invention has the following beneficial effects:

[0052] 1. The inventors of this invention discovered through research that when the infrared spectrum of the molecular sieve is in the wavenumber range of 680-760 cm⁻¹ -1 Two peaks appeared at the point, which effectively inhibited the condensation of the binder and the silanol groups on the molecular sieve surface during the molding process, reducing the pore-blocking effect of the binder. The prepared catalyst is particularly suitable for the benzene alkylation to ethylbenzene reaction, which helps to suppress side reactions, improve the ethyl selectivity in the alkylation product, and reduce the content of the key impurity xylene.

[0053] 2. The inventors of this invention have discovered that the b-axis thickness and the exposure of the crystal plane perpendicular to the b-axis direction of the molecular sieve have a crucial impact on the performance of the benzene alkylation catalyst. Further research by the inventors revealed that when the b-axis thickness of the ZSM-5 molecular sieve is 20-120 nm, preferably 30-100 nm, and the exposure of the crystal plane perpendicular to the b-axis direction is 65%-80%, preferably 67%-75%, it is significantly beneficial to improve the ethylene conversion rate, suppress side reactions, improve the ethyl selectivity in the alkylation product, and reduce the content of the key impurity xylene. It is particularly suitable for the benzene alkylation to ethylbenzene reaction.

[0054] 3. In the preparation process of the catalyst of the present invention, organic compound I and organic compound II are introduced at different times during the molecular sieve preparation process to obtain a specific molecular sieve. Moreover, a polymer mixture is added during the molding process to further reduce the blockage of the molecular sieve micropores by the binder. The resulting catalyst has high micropore volume and mesopore volume, as well as suitable mechanical strength and suitable bulk density. During the reaction process, it further improves the diffusion performance of the reactant molecules, which is beneficial to improving the ethylene conversion rate, suppressing side reactions, and reducing xylene content. It is particularly suitable for industrial benzene and crude ethane cracking gas alkylation reaction equipment to produce ethylbenzene.

[0055] 4. The catalyst of this invention is particularly suitable for reacting benzene with mixed C2 with high ethylene concentration as raw material. Under reaction conditions of high ethylene mass concentration and low molar ratio of benzene and ethylene, the ethylene conversion rate is greater than 99.8%, the ethyl selectivity in the alkylation product is greater than 99.6%, and the mass content of the key impurity xylene is less than 600 ppm. Attached Figure Description

[0056] Figure 1 The XRD pattern of the molecular sieve prepared in Example 1 of this invention;

[0057] Figure 2 SEM image of the molecular sieve prepared in Example 1 of this invention;

[0058] Figure 3 The infrared spectrum of the molecular sieve prepared in Example 1 of this invention;

[0059] Figure 4 The XRD pattern of the molecular sieve prepared in Comparative Example 1 of this invention is shown.

[0060] Figure 5 The infrared spectrum of the molecular sieve prepared in Comparative Example 1 of this invention is shown. Detailed Implementation

[0061] The present invention will now be described in detail with reference to specific embodiments, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments.

[0062] In this invention, the b-axis thickness of the molecular sieve and the exposure of the crystal planes perpendicular to the b-axis direction are obtained by analyzing SEM images. SEM images were obtained using a Hitachi S-4800 cold field emission high-resolution scanning electron microscope. The exposure of the crystal planes perpendicular to the b-axis direction is defined as the proportion of the area of ​​the 010 crystal plane of the ZSM-5 molecular sieve to the total area of ​​all crystal planes.

[0063] In this invention, the micropore volume and mesopore volume are obtained by nitrogen adsorption-desorption test. The nitrogen adsorption-desorption isotherm of the catalyst is tested at liquid nitrogen temperature using a BEL-MAX specific surface area and pore size analyzer manufactured by BELSORP Corporation of Japan. The total pore volume is calculated using the BET equation, and the micropore volume is calculated using the t-plot method. The difference between the total pore volume and the micropore volume is the mesopore volume.

[0064] In this invention, the mechanical strength is obtained using an intelligent particle strength tester. The DLIII type intelligent particle strength tester from Dalian Penghui Technology Development Co., Ltd. is used to test the mechanical strength of the catalyst. The length of the catalyst is 5mm, and it is placed horizontally on the tester. The maximum pressure that the catalyst can withstand when it is crushed is tested. The average value is taken after testing the crushing strength of 20 catalysts.

[0065] In this invention, the XRD pattern of the catalyst was obtained using a Rigaku Ultima IV X-ray powder diffractometer (Japan). The voltage was set to 35 kV, the current to 30 mA, and the scan rate to 1°·min. -1 .

[0066] In this invention, the bulk density of the catalyst is tested using a 1000mL graduated cylinder. The actual weight of the added catalyst (in grams) is divided by the actual volume, and the unit is g·cm³. -3 .

[0067] In this invention, the SiO2 / Al2O3 molar ratio is obtained by ICP testing. A Kontron Model S-35 ICP-AES analyzer is used to perform the ICP test to obtain the silicon-to-aluminum ratio data.

[0068] The molecular sieve structure was characterized using an iS50 infrared spectrometer from Thermo Scientific, USA, with KBr pellets and a wavenumber range of 400-4000 cm⁻¹. -1 .

[0069]

Example 1

[0070] This embodiment is used to synthesize a molecular sieve and a molecular sieve catalyst. The specific preparation process is as follows:

[0071] 208.3 g of tetraethyl silicate, 6.66 g of aluminum sulfate octadechydrate, 270 g of water, 61 g of tetrapropylammonium hydroxide, and 20.64 g of N-aminoethyl-3-aminopropylmethyldimethoxysilane were mixed and then stirred at 70 °C for 10 hours to obtain mixture A1, wherein the ratio of tetraethyl silicate (SiO2) to aluminum sulfate octadechydrate (Al2O3) to water to tetrapropylammonium hydroxide to N-aminoethyl-3-aminopropylmethyldimethoxysilane is 1:0.01:15:0.3:0.1 (molar ratio). Mixtures A1 (26.6 g), B1 (60 g), 6.66 g aluminum sulfate octadechydrate (6.66 g), 270 g water, 14.63 g n-butylamine, and 14.28 g 1,3-diphenyltetramethyldisilazane) were mixed to obtain mixture B1, wherein the molar ratio of fumed silica (SiO2) to aluminum sulfate octadechydrate (Al2O3) was 1:0.01:15:0.2:0.05. B1 was crystallized in a sealed container at 160 °C for 40 h, then centrifuged to obtain a solid. The solid was washed repeatedly with deionized water until the pH of the washing solution reached 7.0. The washed solid was then dried at 160 °C for 5 h to obtain molecular sieve C1.

[0072] Catalyst D1 was obtained by mixing 100 g of C1, 10 g of alumina monohydrate, 90 g of 3% nitric acid aqueous solution, 4 g of guar gum powder, and 8 g of polymer mixture (including 3.2 g of starch and 4.8 g of hexadecyltrimethylammonium bromide) and extruding it into a four-leaf clover shape. Then, it was treated with 130°C for 12 hours; 500°C for 5 hours; 3% ammonium acetate solution at 40°C for 3 hours, with 4 consecutive exchanges; 450°C for 5 hours in a saturated water vapor atmosphere; and 1.0% oxalic acid solution at 50°C for 6 hours.

[0073] The XRD pattern of molecular sieve C1 is as follows: Figure 1 As shown, it exhibits typical diffraction peaks of ZSM-5 molecular sieve. The SEM image of molecular sieve C1 is shown below. Figure 2 As shown, the b-axis thickness of the molecular sieve is 88 nm, and the exposure of the crystal plane perpendicular to the b-axis direction is 71%. The SiO2 / Al2O3 molar ratio of molecular sieve C1 is 101. The infrared spectrum of molecular sieve C1 is as follows... Figure 3 As shown, in the range of 680-760cm -1 Two strong peaks appear at the point, with wave numbers corresponding to the peak vertices of 700 cm⁻¹. -1 and 739cm -1 .

[0074] The micropore volume of catalyst D1 was determined to be 0.13 cm³. 3 ·g -1 The mesopore volume is 0.61 cm³. 3 ·g -1 Its mechanical strength is 106 N / cm, and its bulk density is 0.56 g·cm³. -3 .

[0075]

Example 2

[0076] This embodiment is used to synthesize a molecular sieve and a molecular sieve catalyst. The specific preparation process is as follows:

[0077] 320.54 g of tetrabutyl silicate, 1.33 g of aluminum sulfate octadechydrate, 90 g of water, 10.17 g of tetrapropylammonium hydroxide, 2.25 g of ethylamine and 4.71 g of N-(n-butyl)-3-aminopropyltrimethoxysilane were mixed and then stirred at 50 °C for 28 hours to obtain mixture A2, wherein the ratio of tetrabutyl silicate (SiO2) to aluminum sulfate octadechydrate (Al2O3) to water to tetrapropylammonium hydroxide to ethylamine to N-(n-butyl)-3-aminopropyltrimethoxysilane is 1:0.002:5:0.05:0.05:0.02 (molar ratio). Mixtures A2 (16.39 g), B2 (208.3 g), A2 (1.33 g), B2 (180 g), C3 (6.01 g), D2 (2.25 g), and B2 (1,3-dichloro-1,1,3,3-tetraphenyldisilazane) were mixed to obtain mixture B2. The molar ratio of A2 (as SiO2), D2 (as Al2O3), and B2 (water, D2, D2) was 1:0.002:10:0.1:0.005. B2 was crystallized in a sealed container at 130°C for 60 h. The resulting solid was then centrifuged and washed repeatedly with deionized water until the pH of the washing solution reached 7.0. The washed solid was then dried at 160°C for 5 h to obtain molecular sieve C2.

[0078] Catalyst D2 was obtained by mixing 100 g of C2, 5 g of alumina monohydrate, 80 g of 1% nitric acid aqueous solution, 3 g of guar gum powder, and 5 g of polymer mixture (including 1.5 g of starch and 3.5 g of hexadecyltrimethylammonium bromide) and extruding it into a cylindrical shape. Then, the mixture was treated at 100°C for 15 hours; at 400°C for 10 hours; treated with 1% ammonium chloride solution at 10°C for 5 hours, with 5 consecutive exchanges; treated at 400°C for 8 hours in a saturated water vapor atmosphere; and treated with 0.5% hydrochloric acid solution at 10°C for 8 hours.

[0079] Molecular sieve C2 exhibits typical ZSM-5 molecular sieve diffraction peaks. The b-axis thickness of molecular sieve C2 is 100 nm, and the exposure of the crystal plane perpendicular to the b-axis direction is 67%. The SiO2 / Al2O3 molar ratio of molecular sieve C2 is 500. The infrared spectrum of molecular sieve C2 is in the range of 680-760 cm⁻¹. -1 Two strong peaks appear at the point, with wave numbers corresponding to the peak vertices of 700 cm⁻¹. -1 and 740cm -1 .

[0080] The micropore volume of catalyst D2 was determined to be 0.15 cm³. 3 ·g -1 The mesopore volume is 0.41 cm³. 3 ·g -1Its mechanical strength is 118 N / cm, and its bulk density is 0.51 g·cm³. -3 .

[0081]

Example 3

[0082] This embodiment is used to synthesize a molecular sieve and a molecular sieve catalyst. The specific preparation process is as follows:

[0083] 208.3 g of tetrapropyl silicate, 13.33 g of aluminum sulfate octadechydrate, 360 g of water, 42.57 g of piperidine, and 52.89 g of N-(2-aminoethyl)-3-aminopropyltriethoxysilane were mixed and then stirred at 80 °C for 6 hours to obtain mixture A3, wherein the ratio of tetrapropyl silicate (SiO2) to aluminum sulfate octadechydrate (Al2O3) to water, piperidine, and N-(2-aminoethyl)-3-aminopropyltriethoxysilane was 1:0.02:20:0.5:0.2 (molar ratio). Mixture B3 was obtained by mixing 132.87 g of mixture A3, 60 g of silica powder, 13.33 g of boehmite, 450 g of water, 46.48 g of hexamethylenediamine, and 51.24 g of 1,3-diphenyltetraethyldisilazane. The molar ratio of silica powder (SiO2): boehmite (Al2O3): water:hexamethylenediamine:1,3-diphenyltetraethyldisilazane was 1:0.02:25:0.4:0.15. B3 was crystallized in a sealed container at 180 °C for 10 h. The resulting solid was then centrifuged and washed repeatedly with deionized water until the pH of the washing solution reached 7.0. The washed solid was then dried at 160 °C for 5 h to obtain molecular sieve C3.

[0084] Catalyst D3 was obtained by mixing 100g C3, 20g alumina monohydrate, 100g nitric acid aqueous solution (5% by mass), 5g guar gum powder, and 10g polymer mixture (including 5g starch and 5g hexadecyltrimethylammonium bromide) and extruding it into a four-leaf clover shape. Then, the mixture was treated at 150℃ for 10 hours, 550℃ for 4 hours, 70℃ for 2 hours with 5% ammonium nitrate solution (repeated three times), 500℃ for 2 hours in a saturated steam atmosphere, and 90℃ for 2 hours with 2.0% nitric acid solution.

[0085] Molecular sieve C3 exhibits typical ZSM-5 molecular sieve diffraction peaks. The b-axis thickness of molecular sieve C3 is 32 nm, and the exposure of the crystal plane perpendicular to the b-axis direction is 75%. The SiO2 / Al2O3 molar ratio of molecular sieve C3 is 50. The infrared spectrum of molecular sieve C3 is in the range of 680-760 cm⁻¹. -1 Two strong peaks appear at the point, with wave numbers corresponding to the peak vertices of 700 cm⁻¹. -1 and 740cm -1 .

[0086] The micropore volume of catalyst D3 was determined to be 0.16 cm³. 3 ·g -1 The mesopore volume is 0.76 cm³. 3 ·g -1 Its mechanical strength is 65 N / cm, and its bulk density is 0.50 g·cm³. -3 .

[0087] Comparative Example 1

[0088] Compared with Example 1, the only difference is that 1,3-diphenyltetramethyldisilazane was not added. The specific preparation process of the molecular sieve and molecular sieve catalyst is as follows:

[0089] 208.3 g of tetraethyl silicate, 6.66 g of aluminum sulfate octadechydrate, 270 g of water, 61 g of tetrapropylammonium hydroxide, and 20.64 g of N-aminoethyl-3-aminopropylmethyldimethoxysilane were mixed and then stirred at 70 °C for 10 hours to obtain mixture dA1, wherein the molar ratio of tetraethyl silicate (SiO2): aluminum sulfate octadechydrate (Al2O3): water: tetrapropylammonium hydroxide: N-aminoethyl-3-aminopropylmethyldimethoxysilane was 1:0.01:15:0.3:0.1. 26.6 g of mixture dA1, 60 g of silica, 6.66 g of aluminum sulfate octadechydrate, 270 g of water, and 14.63 g of n-butylamine were mixed to obtain mixture dB1, wherein the molar ratio of silica (SiO2): aluminum sulfate octadechydrate (Al2O3): water: n-butylamine was 1:0.01:15:0.2. dB1 was crystallized in a sealed container at 160°C for 40 hours, then centrifuged to obtain a solid. The solid was washed multiple times with deionized water until the pH of the washing solution reached 7.0. The washed solid was then dried at 160°C for 5 hours to obtain molecular sieve dC1.

[0090] The catalyst dD1 was obtained by mixing 100 g of dC1, 10 g of alumina monohydrate, 90 g of 3% nitric acid aqueous solution, 4 g of guar gum powder, and 8 g of polymer mixture (including 3.2 g of starch and 4.8 g of hexadecyltrimethylammonium bromide) and extruding it into a four-leaf clover shape. Then, the mixture was treated with 130 °C for 12 hours, 500 °C for 5 hours, 3% ammonium acetate solution at 40 °C for 3 hours, and this process was repeated 4 times. The mixture was then treated with 450 °C for 5 hours in a saturated steam atmosphere and finally treated with 1.0% oxalic acid solution at 50 °C for 6 hours.

[0091] The XRD pattern of molecular sieve dC1 is as follows: Figure 4As shown, it exhibits typical ZSM-5 molecular sieve diffraction peaks. The b-axis thickness of molecular sieve dC1 is 185 nm, and the exposure of the crystal plane perpendicular to the b-axis direction is 61%. The SiO2 / Al2O3 molar ratio of molecular sieve dC1 is 101. The infrared spectrum of molecular sieve dC1 is shown below. Figure 5 As shown, in the range of 680-760cm -1 No two strong peaks were observed.

[0092] The micropore volume of catalyst dD1 was determined to be 0.11 cm³. 3 ·g -1 The mesopore volume is 0.53 cm³. 3 ·g -1 Its mechanical strength is 104 N / cm, and its bulk density is 0.55 g·cm³. -3 .

[0093] Comparative Example 2

[0094] Compared with Example 1, the only difference is that N-aminoethyl-3-aminopropylmethyldimethoxysilane was not added. The specific preparation process of the molecular sieve and molecular sieve catalyst is as follows:

[0095] Mixing 208.3 g of tetraethyl silicate, 6.66 g of aluminum sulfate octadechydrate, 270 g of water, and 61 g of tetrapropylammonium hydroxide, and then stirring at 70 °C for 10 hours, yielded mixture dA2. The molar ratio of tetraethyl silicate (SiO2): aluminum sulfate octadechydrate (Al2O3): water: tetrapropylammonium hydroxide was 1:0.01:15:0.3. Mixing 26.6 g of mixture dA2, 60 g of silica, 6.66 g of aluminum sulfate octadechydrate, 270 g of water, 14.63 g of n-butylamine, and 14.28 g of 1,3-diphenyltetramethyldisilazane yielded mixture dB2. The molar ratio of silica (SiO2): aluminum sulfate octadechydrate (Al2O3): water: n-butylamine: 1,3-diphenyltetramethyldisilazane was 1:0.01:15:0.2:0.05. dB2 was crystallized in a sealed container at 160°C for 40 hours, then centrifuged to obtain a solid. The solid was washed multiple times with deionized water until the pH of the washing solution reached 7.0. The washed solid was then dried at 160°C for 5 hours to obtain molecular sieve dC2.

[0096] The catalyst dD2 was obtained by mixing 100 g of dC2, 10 g of alumina monohydrate, 90 g of 3% nitric acid aqueous solution, 4 g of guar gum powder, and 8 g of polymer mixture (including 3.2 g of starch and 4.8 g of hexadecyltrimethylammonium bromide) and extruding it into a four-leaf clover shape. Then, the mixture was treated with 130 °C for 12 hours, 500 °C for 5 hours, 3% ammonium acetate solution at 40 °C for 3 hours, and this process was repeated 4 times. The mixture was then treated with 450 °C for 5 hours in a saturated steam atmosphere and finally treated with 1.0% oxalic acid solution at 50 °C for 6 hours.

[0097] The XRD pattern of molecular sieve dC2 exhibits typical ZSM-5 molecular sieve diffraction peaks. The b-axis thickness of molecular sieve dC2 is 160 nm, and the exposure of the crystal plane perpendicular to the b-axis direction is 52%. The SiO2 / Al2O3 molar ratio of molecular sieve dC2 is 10:1. The infrared spectrum of molecular sieve dC2 is in the range of 680-760 cm⁻¹. -1 Two strong peaks appear at the point, with wave numbers corresponding to the peak vertices of 700 cm⁻¹. -1 and 740cm -1 .

[0098] The micropore volume of catalyst dD2 was determined to be 0.12 cm³. 3 ·g -1 The mesopore volume is 0.60 cm³. 3 ·g -1 Its mechanical strength is 104 N / cm, and its bulk density is 0.56 g·cm³. -3 .

[0099] Comparative Example 3

[0100] Compared with Example 1, the only difference is that equimolar amounts of N-aminoethyl-3-aminopropylmethyldimethoxysilane are used instead of 1,3-diphenyltetramethyldisilazane. The specific preparation process of the molecular sieve and molecular sieve catalyst is as follows:

[0101] 208.3 g of tetraethyl silicate, 6.66 g of aluminum sulfate octadechydrate, 270 g of water, 61 g of tetrapropylammonium hydroxide, and 20.64 g of N-aminoethyl-3-aminopropylmethyldimethoxysilane were mixed and then stirred at 70 °C for 10 hours to obtain mixture dA3, wherein the ratio of tetraethyl silicate (SiO2) to aluminum sulfate octadechydrate (Al2O3) to water to tetrapropylammonium hydroxide to N-aminoethyl-3-aminopropylmethyldimethoxysilane is 1:0.01:15:0.3:0.1 (molar ratio). Mixture dB3 was obtained by mixing 26.6 g of dA3, 60 g of silica, 6.66 g of aluminum sulfate octadechydrate, 270 g of water, 14.63 g of n-butylamine, and 10.32 g of N-aminoethyl-3-aminopropylmethyldimethoxysilane. The molar ratio of silica (SiO2): aluminum sulfate octadechydrate (Al2O3): water: n-butylamine: N-aminoethyl-3-aminopropylmethyldimethoxysilane was 1:0.01:15:0.2:0.05. dB3 was crystallized in a sealed container at 160 °C for 40 h. The resulting solid was then centrifuged and washed repeatedly with deionized water until the pH of the washing solution reached 7.0. The washed solid was then dried at 160 °C for 5 h to obtain molecular sieve dC3.

[0102] The catalyst dD3 was obtained by mixing 100 g of dC3, 10 g of alumina monohydrate, 90 g of 3% nitric acid aqueous solution, 4 g of guar gum powder, and 8 g of polymer mixture (including 3.2 g of starch and 4.8 g of hexadecyltrimethylammonium bromide) and extruding it into a four-leaf clover shape. Then, the mixture was treated with 130 °C for 12 hours, 500 °C for 5 hours, 3% ammonium acetate solution at 40 °C for 3 hours, and this process was repeated 4 times. The mixture was then treated with 450 °C for 5 hours in a saturated steam atmosphere and finally treated with 1.0% oxalic acid solution at 50 °C for 6 hours.

[0103] The XRD pattern of molecular sieve dC3 exhibits typical diffraction peaks characteristic of ZSM-5 molecular sieves. The b-axis thickness of molecular sieve dC3 is 135 nm, and the exposure of the crystal plane perpendicular to the b-axis direction is 63%. The SiO2 / Al2O3 molar ratio of molecular sieve dC3 is 10:1. The infrared spectrum of molecular sieve dC3 is in the range of 680-760 cm⁻¹. -1 No two strong peaks were observed.

[0104] The micropore volume of catalyst dD3 was determined to be 0.12 cm³. 3 ·g -1 The mesopore volume is 0.59 cm³. 3 ·g -1 Its mechanical strength is 102 N / cm, and its bulk density is 0.57 g·cm³. -3 .

[0105] Comparative Example 4

[0106] Compared with Example 1, the only difference is that equimolar amounts of 1,3-diphenyltetramethyldisilazane are used instead of N-aminoethyl-3-aminopropylmethyldimethoxysilane. The specific preparation process of the molecular sieve and molecular sieve catalyst is as follows:

[0107] 208.3 g of tetraethyl silicate, 6.66 g of aluminum sulfate octadechydrate, 270 g of water, 61 g of tetrapropylammonium hydroxide, and 28.56 g of 1,3-diphenyltetramethyldisilazane were mixed and then stirred at 70 °C for 10 hours to obtain mixture dA4, wherein the ratio of tetraethyl silicate (SiO2) to aluminum sulfate octadechydrate (Al2O3) to water to tetrapropylammonium hydroxide to 1,3-diphenyltetramethyldisilazane is 1:0.01:15:0.3:0.1 (molar ratio). Mixture dB4 was obtained by mixing 26.6 g of dA4, 60 g of silica, 6.66 g of aluminum sulfate octadecylhydrate, 270 g of water, 14.63 g of n-butylamine, and 14.28 g of 1,3-diphenyltetramethyldisilazane. The molar ratio of silica (SiO2):aluminum sulfate octadecylhydrate (Al2O3):water:n-butylamine:1,3-diphenyltetramethyldisilazane was 1:0.01:15:0.2:0.05. dB4 was crystallized in a sealed container at 160 °C for 40 h. The resulting solid was then centrifuged and washed repeatedly with deionized water until the pH of the washing solution reached 7.0. The washed solid was then dried at 160 °C for 5 h to obtain molecular sieve dC4.

[0108] The catalyst dD4 was obtained by mixing 100 g of dC4, 10 g of alumina monohydrate, 90 g of 3% nitric acid aqueous solution, 4 g of guar gum powder, and 8 g of polymer mixture (including 3.2 g of starch and 4.8 g of hexadecyltrimethylammonium bromide) and extruding it into a four-leaf clover shape. Then, the mixture was treated with 130 °C for 12 hours, 500 °C for 5 hours, 3% ammonium acetate solution at 40 °C for 3 hours, and this process was repeated 4 times. The mixture was then treated with 450 °C for 5 hours in a saturated steam atmosphere and finally treated with 1.0% oxalic acid solution at 50 °C for 6 hours.

[0109] Molecular sieve dC4 exhibits typical diffraction peaks of ZSM-5 molecular sieves. The b-axis thickness of molecular sieve dC4 is 142 nm, and the exposure of the crystal plane perpendicular to the b-axis direction is 53%. The SiO2 / Al2O3 molar ratio of molecular sieve dC4 is 10:1. The infrared spectrum of molecular sieve dC4 is in the range of 680-760 cm⁻¹. -1 Two strong peaks appear at the point, with wave numbers corresponding to the peak vertices of 700 cm⁻¹. -1 and 740cm -1 .

[0110] The micropore volume of catalyst dD4 was determined to be 0.12 cm³. 3 ·g -1 The mesopore volume is 0.60 cm³. 3 ·g -1 Its mechanical strength is 101 N / cm, and its bulk density is 0.56 g·cm³. -3 .

[0111] Comparative Example 5

[0112] The only difference from Example 1 is that N-aminoethyl-3-aminopropylmethyldimethoxysilane and 1,3-diphenyltetramethyldisilazane are added simultaneously.

[0113] 208.3 g of tetraethyl silicate, 6.66 g of aluminum sulfate octadecahydrate, 270 g of water and 61 g of tetrapropylammonium hydroxide were mixed and then stirred at 70 °C for 10 hours to obtain mixture dA5, wherein the ratio of tetraethyl silicate (SiO2), aluminum sulfate octadecahydrate (Al2O3), water and tetrapropylammonium hydroxide was 1:0.01:15:0.3 (molar ratio). Mixture dB5 was obtained by mixing 26.6 g of dA5, 60 g of silica, 6.66 g of aluminum sulfate octadechydrate, 270 g of water, 14.63 g of n-butylamine, 0.97 g of N-aminoethyl-3-aminopropylmethyldimethoxysilane, and 14.28 g of 1,3-diphenyltetramethyldisilazane. The molar ratio of silica (SiO2):aluminum sulfate octadechydrate (Al2O3):water:n-butylamine:1,3-diphenyltetramethyldisilazane was 1:0.01:15:0.2:0.05. dB5 was crystallized in a sealed container at 160 °C for 40 h. The resulting solid was then centrifuged and washed repeatedly with deionized water until the pH of the washing solution reached 7.0. The washed solid was then dried at 160 °C for 5 h to obtain molecular sieve dC5.

[0114] The catalyst dD5 was obtained by mixing 100 g of dC5, 10 g of alumina monohydrate, 90 g of 3% nitric acid aqueous solution, 4 g of guar gum powder, and 8 g of polymer mixture (including 3.2 g of starch and 4.8 g of hexadecyltrimethylammonium bromide) and extruding it into a four-leaf clover shape. Then, the catalyst was treated with 130 °C for 12 hours, 500 °C for 5 hours, 3% ammonium acetate solution at 40 °C for 3 hours, and repeated 4 times. The catalyst was then treated with 450 °C for 5 hours in a saturated steam atmosphere and 1.0% oxalic acid solution at 50 °C for 6 hours.

[0115] Molecular sieve dC5 exhibits typical ZSM-5 molecular sieve diffraction peaks. The b-axis thickness of molecular sieve dC5 is 148 nm, and the exposure of the crystal plane perpendicular to the b-axis direction is 61%. The SiO2 / Al2O3 molar ratio of molecular sieve dC5 is 10:1. The infrared spectrum of molecular sieve dC5 is in the range of 680-760 cm⁻¹. -1 Two strong peaks appear at the point, with wave numbers corresponding to the peak vertices of 700 cm⁻¹. -1 and 740cm -1 .

[0116] The micropore volume of catalyst dD5 was determined to be 0.12 cm³. 3 ·g -1 The mesopore volume is 0.60 cm³. 3 ·g -1 Its mechanical strength is 103 N / cm, and its bulk density is 0.56 g·cm³. -3 .

[0117]

Examples 4-6

[0118] Catalysts D1-D3 prepared in Examples 1-3 were applied to the benzene alkylation reaction to ethylbenzene, wherein the ethylene mass concentration was 70%, the reaction temperature was 320°C, the pressure was 2.0 MPa, and the ethylene mass hourly space velocity was 0.5 h⁻¹. -1 Under the condition of a benzene to ethylene molar ratio of 6.0, the ethylene conversion, ethyl selectivity in the alkylation products, and the content of the key impurity xylene were tested. The test results are shown in Table 1.

[0119] Comparative Examples 6-10

[0120] Catalysts dD1-dD5 prepared in Comparative Examples 1-5 were applied to the benzene alkylation reaction to ethylbenzene, wherein the ethylene mass concentration was 70%, the reaction temperature was 320℃, the pressure was 2.0 MPa, and the ethylene mass hourly space velocity was 0.5 h⁻¹. -1 Under the condition of a benzene to ethylene molar ratio of 6.0, the ethylene conversion, ethyl selectivity in the alkylation products, and the content of the key impurity xylene were tested. The test results are shown in Table 1.

[0121] Table 1 Results of the phenylalkylation reaction to produce ethylbenzene

[0122]

[0123]

[0124] 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 inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combining the various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for preparing ZSM-5 molecular sieve, comprising: (a) Silicon source I, aluminum source I, water, template agent I and organic matter I are mixed and processed to obtain mixture A; (b) Mix mixture A, silicon source II, aluminum source II, water, template agent II, and organic matter II to obtain mixture B; (c) After crystallization, mixture B is subjected to liquid-solid separation, washing, and drying to obtain the molecular sieve; In step (a), organic compound I is a silane containing aminopropyl groups, which is one or more of N-aminoethyl-3-aminopropylmethyldimethoxysilane, N-(n-butyl)-3-aminopropyltrimethoxysilane, or N-(2-aminoethyl)-3-aminopropyltriethoxysilane; the molar ratios of silicon source I, aluminum source I, water, template agent I, and organic compound I in step (a) are as follows: silicon source I: aluminum source I: water: template agent I: organic compound I = 1:(0.002-0.02):(5-20):(0.1-0.5):(0.02-0.2), where silicon source I and aluminum source I are calculated as SiO2 and Al2O3, respectively; In step (b), organic compound II is a phenyl-containing disilazane, which is one or more of 1,3-diphenyltetramethyldisilazane, 1,3-dichloro-1,1,3,3-tetraphenyldisilazane, or 1,3-diphenyltetraethyldisilazane; the molar ratios of silicon source II, aluminum source II, water, template agent II, and organic compound II in step (b) are as follows: silicon source II: aluminum source II: water: template agent II: organic compound II = 1: (0.002-0.02): (10-25): (0.1-0.4): (0.005-0.15); the mass ratio of the mixture A to the total mass of the five substances silicon source II, aluminum source II, water, template agent II, and organic compound II is (0.04-0.22): 1, wherein silicon source II and aluminum source II are calculated as SiO2 and Al2O3, respectively.

2. The preparation method according to claim 1, characterized in that: In step (a), silicon source I is one or more of tetraethyl silicate, tetrapropyl silicate, and tetrabutyl silicate; and / or, aluminum source I in step (a) is one or more of aluminum sulfate, aluminum isopropoxide, sodium aluminate, and boehmite; and / or, template agent I in step (a) is one or more of tetrapropylammonium hydroxide, ethylamine, ethylenediamine, n-butylamine, butanediamine, hexamethyleneimine, piperidine, piperazine, and homopiperazine.

3. The preparation method according to claim 1, characterized in that: In step (b), silicon source II is one or more of silica sol, silica fume, silica powder, tetramethyl silicate, tetraethyl silicate, tetrapropyl silicate, and tetrabutyl silicate; and / or, in step (b), aluminum source II is one or more of aluminum nitrate, aluminum chloride, aluminum sulfate, aluminum isopropoxide, sodium aluminate, and boehmite; and / or, in step (b), template agent II is one or more of tetrapropylammonium bromide, tetrapropylammonium hydroxide, ethylamine, ethylenediamine, n-propylamine, propylenediamine, n-butylamine, butylenediamine, n-hexylamine, hexamethylenediamine, ammonia, hexamethyleneimine, piperidine, piperazine, and hyperpiperazine.

4. The preparation method according to claim 1, characterized in that, The processing conditions in step (a) are stirring at 50-80 °C for 5-30 hours under sealed conditions; and / or, the crystallization conditions in step (c) are crystallization at 130-180 °C for 10-60 hours under sealed conditions.

5. ZSM-5 molecular sieve prepared by any of the preparation methods described in claims 1-4.

6. The molecular sieve according to claim 5, characterized in that: The infrared spectrum of the molecular sieve is in the wavenumber range of 680-760 cm⁻¹. -1 Two strong peaks appeared at the location.

7. The molecular sieve according to claim 5, characterized in that: The molecular sieve has a b-axis thickness of 20-120 nm and a crystal plane exposure perpendicular to the b-axis of 65%-80%.

8. The molecular sieve according to claim 7, characterized in that: The molecular sieve has a b-axis thickness of 30-100 nm and a crystal plane exposure perpendicular to the b-axis of 65%-75%.

9. The molecular sieve according to claim 5, characterized in that: The SiO2 / Al2O3 molar ratio of the molecular sieve is 50-500.

10. A catalyst for the alkylation of benzene to ethylbenzene, characterized in that: The catalyst comprises ZSM-5 molecular sieve prepared by any one of the preparation methods of claims 1-4, optionally comprising alumina.

11. The catalyst according to claim 10, characterized in that: The catalyst, based on its mass, contains more than 80% molecular sieve and less than 20% alumina.

12. The catalyst according to claim 11, characterized in that: The catalyst, based on its mass, contains 80%-90% molecular sieve and 10%-20% alumina.

13. The catalyst according to claim 10, characterized in that: The catalyst has a micropore volume of 0.11-0.16 cm³. 3 ·g -1 The mesopore volume is 0.40-0.80 cm³. 3 ·g -1 Its mechanical strength is 60-120 N / cm, and its bulk density is 0.50-0.60 g·cm³. -3 .

14. A method for preparing a catalyst for the alkylation of benzene to ethylbenzene, comprising: (d) The ZSM-5 molecular sieve, alumina and polymer mixture prepared by any one of the methods described in claims 1-4 are mixed and shaped, and then dried, calcined, subjected to ammonium exchange, steam treatment and acid washing to obtain the catalyst.

15. The preparation method according to claim 14, characterized in that: In step (d), the alumina is alumina monohydrate; and / or, in step (d), the polymer mixture is a mixture of starch and hexadecyltrimethylammonium bromide, wherein the starch accounts for 30%-50% of the mass of the polymer mixture.

16. The preparation method according to claim 14, characterized in that: In step (d), the mass ratio of molecular sieve, alumina and polymer mixture is: molecular sieve: alumina: polymer mixture = 1: (0.05-0.2): (0.05-0.1).

17. The preparation method according to claim 14, characterized in that: In step (d), the drying conditions are 100-150 ℃ for 10-15 hours; the calcination conditions are 400-550 ℃ for 4-10 hours; the steam treatment conditions are 400-500 ℃ for 3-8 hours in a saturated steam atmosphere; and the pickling conditions are 0.5%-2.0% acid solution at 10-90 ℃ for 2-8 hours.

18. A method for producing ethylbenzene by benzene alkylation, characterized in that: The reactants benzene and ethylene are contacted with the catalyst described in any one of claims 10-13 or the catalyst prepared by any one of claims 14-17 to generate ethylbenzene.

19. The method according to claim 18, characterized in that: The ethylene feedstock has an ethylene mass concentration of 10%-100%; and / or, the reaction conditions are as follows: reaction temperature of 300-380 ℃, reaction pressure of 0.4-2.5 MPa, and ethylene mass hourly space velocity of 0.1-3.0 h⁻¹. -1 The molar ratio of benzene to ethylene is 4.0-6.0.

Images