ZSM-5 molecular sieve and preparation and application thereof

Abstract

The invention discloses a ZSM-5 molecular sieve as well as preparation and application thereof. The preparation method of the molecular sieve comprises the following steps: (a) mixing a silicon source I, an aluminum source I, water, a template agent I and an organic matter I, and treating to obtain a mixture A; (b) mixing the mixture A, a silicon source II, an aluminum source II, water, a template agent II and an organic matter II to obtain a mixture B; and (c) crystallizing the mixture B, and performing liquid-solid separation, washing and drying to obtain the molecular sieve, wherein the organic matter I is silane containing aminopropyl. The catalyst prepared from the molecular sieve is especially suitable for a reaction for preparing ethylbenzene through alkylation of benzene and ethylene, the selectivity of ethyl in an alkylated product is high, and the mass content of key impurity xylene is low.

Description

Technical Field

[0001] The 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 Art

[0002] Ethylbenzene is an important organic chemical raw material. It is mainly used in the downstream production of styrene, and then in the synthesis of polymer materials such as resins and plastics. It is widely used in the fields of automobiles, electronics, aviation, urban construction or daily necessities, and is of great significance to the development of the national economy.

[0003] Ethylbenzene is generally prepared by alkylation reaction of benzene and ethylene under the catalytic action of acidic molecular sieves. The sources of ethylene are diversified, and can be pure ethylene, dilute ethylene and ethanol. Among them, using dilute ethylene as raw material has obvious cost advantage, and can create more economic benefits for enterprises. Dilute ethylene generally comes from the tail gas of FCC and DCC devices, or is crude ethane cracking gas, wherein the mass concentration of ethylene is generally 10-70wt%. Dilute ethylene components are complex, and in addition to containing some alkanes, nitrogen or hydrogen that do not participate in the alkylation reaction, it also contains propylene, butene or other olefins that can react with benzene. The presence of these impurities in the raw materials will lead to an increase in side reactions during the reaction, and the ethyl selectivity in the alkylated product decreases. At the same time, the key impurity xylene content that is difficult to separate increases, which seriously affects the quality of ethylbenzene products.

[0004] CN1310048A discloses a method for improving the selectivity and stability of a zeolite catalyst for producing ethylbenzene. The method prepares a catalyst by modifying the outer surface of a ZSM-5 zeolite containing an organic amine (template) with an organic acid. When the catalyst obtained by the method is used for the alkylation of benzene and ethylene to produce ethylbenzene, when the ethylene conversion rate reaches 95%, the ethyl selectivity is only 97.5%, and the xylene content in the product is still as high as 1000ppm. Therefore, the catalyst still has the problems of low ethyl selectivity and high content of key impurity xylene. Summary of the invention

[0005] The present invention provides a ZSM-5 molecular sieve, a catalyst for preparing ethylbenzene by alkylation of benzene, and preparation and application thereof. The ZSM-5 molecular sieve of the present invention is a novel ZSM-5 molecular sieve. The catalyst prepared by the molecular sieve of the present invention is used in the reaction of preparing ethylbenzene by gas-phase alkylation of benzene and ethylene, and can effectively improve the selectivity of ethyl in the alkylation product, inhibit side reactions, and reduce the content of xylene.

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

[0007] (a) mixing a silicon source I, an aluminum source I, water, a template agent I and an organic matter I, and treating the mixture to obtain a mixture A;

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

[0009] (c) crystallizing the mixture B, performing liquid-solid separation, washing, and drying to obtain the molecular sieve;

[0010] Wherein, the organic substance I in step (a) is an aminopropyl-containing silane, 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 characteristics:

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

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

[0014] In the above technical scheme, preferably, in step (a), the 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 scheme, preferably, in step (a), the molar ratios of silicon source I, aluminum source I, water, template I and organic matter I are respectively silicon source I: aluminum source I: water: template 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 treatment condition in step (a) is to stir and treat at 50-80° C. for 5-30 hours under closed conditions.

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

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

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

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

[0021] In the above technical scheme, preferably, the organic substance II in step (b) is a disilazane containing a phenyl group, preferably one or more of 1,3-diphenyltetramethyldisilazane, 1,3-dichloro-1,1,3,3-tetraphenyldisilazane or 1,3-diphenyltetraethyldisilazane.

[0022] In the above technical scheme, preferably, in step (b), the molar ratios of silicon source II, aluminum source II, water, template II and organic matter II are respectively silicon source II: aluminum source II: water: template 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 of silicon source II, aluminum source II, water, template II and organic matter II is (0.04-0.22): 1, wherein the silicon source II and the 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 closed conditions.

[0024] In the above technical solution, preferably, the liquid-solid separation in step (c) is carried out by filter paper filtration, centrifugation or plate and frame filter pressing, etc.; the washing condition is to wash the solid obtained by liquid-solid separation with deionized water for multiple times until the pH value of the washing liquid is 7-8. The drying condition is to dry at 100-200°C 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 wave number range of 680-760cm -1 There are two strong peaks.

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

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

[0029] The third aspect of the present invention provides a catalyst for preparing ethylbenzene by alkylation of benzene, wherein the catalyst comprises a ZSM-5 molecular sieve, and 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, in the catalyst, the ZSM-5 molecular sieve exists in a calcined state.

[0031] In the above technical solution, the catalyst, in addition to the molecular sieve, optionally includes aluminum oxide, silicon oxide or a mixture thereof.

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

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

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

[0035] (d) The ZSM-5 molecular sieve prepared by the method of the first aspect, alumina and a polymer mixture are mixed and molded, and then dried, calcined, ammonium exchanged, steam treated, and acid washed to obtain the catalyst.

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

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

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

[0039] In the above technical solution, preferably, 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);

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

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

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

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

[0044] In the above technical scheme, preferably, in step (d), the forming shape is cylindrical, clover-shaped, four-leaf clover-shaped, gear-shaped, etc.; the drying condition is 100-150° C. for 10-15 hours; the roasting condition is 400-550° C. for 4-10 hours; the ammonium exchange condition is to use an ammonium salt solution with a mass concentration of 1%-5% at 10-70° C. for 2-5 hours, and exchange continuously 2-5 times, and the ammonium salt is one of ammonium sulfate, ammonium chloride, ammonium acetate or ammonium nitrate; the water vapor treatment condition is to use a saturated water vapor atmosphere at 400-500° C. for 3-8 hours; the pickling condition is to use an acid solution with a mass concentration of 0.5%-2.0% at 10-90° C. 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 producing ethylbenzene by alkylation of benzene prepared by the method of the fourth aspect.

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

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

[0048] A sixth aspect of the present invention provides a method for preparing ethylbenzene by alkylation of benzene, 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 mass concentration of ethylene in the ethylene raw material is 10%-100%.

[0050] In the above technical solution, preferably, the reaction temperature is 300-380°C, the reaction pressure is 0.4-2.5MPa, and the ethylene mass 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 the present invention have found that when the infrared spectrum of molecular sieve is in the wave number range of 680-760cm -1 Two peaks appear at the bottom of the catalyst, which can effectively inhibit the condensation of the binder and the silanol group on the surface of the molecular sieve during the molding process, reducing the pore blocking effect of the binder. The prepared catalyst is particularly suitable for the alkylation of benzene to ethylbenzene, which is beneficial to inhibit side reactions, improve the selectivity of ethyl in the alkylation product, and reduce the content of the key impurity xylene.

[0053] 2. The inventors of the present invention have found through research that the b-axis thickness of the molecular sieve and the exposure of the crystal plane perpendicular to the b-axis are crucial to the performance of the benzene alkylation catalyst. The inventors have further found that when the b-axis thickness of the ZSM-5 molecular sieve is 20-120nm, preferably 30-100nm, and the exposure of the crystal plane perpendicular to the b-axis is 65%-80%, preferably 67%-75%, it is obviously beneficial to improve the ethylene conversion rate, inhibit side reactions, increase the ethyl selectivity in the alkylation product, and reduce the content of the key impurity xylene, which is particularly suitable for the benzene alkylation reaction to produce ethylbenzene.

[0054] 3. In the preparation process of the catalyst of the present invention, first, in the process of preparing the molecular sieve, organic matter I and organic matter II are introduced at different times to obtain a specific molecular sieve, and a polymer mixture is added during the molding process, which further reduces the blockage of the micropores of the molecular sieve by the binder. The obtained catalyst has high micropore volume and mesopore volume, as well as suitable mechanical strength and suitable bulk density. The diffusion performance of the reaction molecules is further improved during the reaction process, which is beneficial to improving the ethylene conversion rate, inhibiting side reactions, and reducing the xylene content. The catalyst is particularly suitable for an alkylation reaction device for preparing ethylbenzene from industrial benzene and crude ethane cracking gas.

[0055] 4. The catalyst of the present invention is particularly suitable for preparing ethylbenzene by reacting mixed carbon dioxide with high ethylene concentration as raw material with benzene. Under the reaction conditions of high ethylene mass concentration and low molar ratio of benzene to 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 600ppm. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0057] Figure 2 This is a SEM photo of the molecular sieve prepared in Example 1 of the present invention;

[0058] Figure 3 This is the infrared spectrum of the molecular sieve prepared in Example 1 of the present invention;

[0059] Figure 4 XRD spectrum of the molecular sieve prepared in Comparative Example 1 of the present invention;

[0060] Figure 5 This is the infrared spectrum of the molecular sieve prepared in Comparative Example 1 of the present invention. DETAILED DESCRIPTION

[0061] The present invention is described in detail below in conjunction with specific implementation modes, but it should be understood that the protection scope of the present invention is not limited by the specific implementation modes.

[0062] The b-axis thickness of the molecular sieve and the exposure of the crystal plane perpendicular to the b-axis direction in the present invention are obtained by analyzing SEM photos, and the SEM photos are obtained using a Hitachi S-4800 cold field emission high-resolution scanning electron microscope produced by Hitachi. Among them, the exposure of the crystal plane perpendicular to the b-axis direction is the ratio of the area of ​​the ZSM-5 molecular sieve 010 crystal plane to the total area of ​​all crystal planes.

[0063] In the present invention, the micropore volume and the 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 produced by BELSORP Co., Ltd. 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 the present invention, the mechanical strength is obtained by using an intelligent particle strength tester. The DLIII type intelligent particle strength tester of Dalian Penghui Technology Development Co., Ltd. is used to test the mechanical strength of the catalyst. The length of the measured catalyst is 5 mm, and it is placed horizontally on the tester to test the maximum pressure that the catalyst can withstand when it is broken. After testing the crushing strength of 20 catalysts, the average value is taken.

[0065] In the present invention, the XRD spectrum of the catalyst was obtained by using the Ultima IV X-ray powder diffractometer produced by Rigaku Corporation of Japan. The voltage was selected as 35 kV, the current was selected as 30 mA, and the scanning speed was 1°·min -1 .

[0066] In the present invention, the bulk density of the catalyst is calculated by dividing the actual weight of the added catalyst (unit: g) by the actual volume using a 1000 mL graduated cylinder as the container, and the unit is g·cm -3 .

[0067] In the present invention, the SiO2 / Al2O3 molar ratio is obtained by ICP testing, and the ICP test is performed using a Kontron Model S-35 ICP-AES analyzer to obtain silicon-aluminum ratio data.

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

[0069] [Example 1]

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

[0071] 208.3 g of tetraethyl silicate, 6.66 g of aluminum sulfate 18hydrate, 270 g of water, 61 g of tetrapropylammonium hydroxide and 20.64 g of N-aminoethyl-3-aminopropylmethyldimethoxysilane are mixed, and then stirred at 70°C for 10 hours to obtain a mixture A1, wherein tetraethyl silicate is calculated as SiO2: aluminum sulfate 18hydrate is calculated as Al2O3: water: tetrapropylammonium hydroxide: N-aminoethyl-3-aminopropylmethyldimethoxysilane = 1:0.01:15:0.3:0.1 (molar ratio). Mix 26.6 g of mixture A1, 60 g of white carbon black, 6.66 g of aluminum sulfate 18 hydrate, 270 g of water, 14.63 g of n-butylamine and 14.28 g of 1,3-diphenyltetramethyldisilazane to obtain mixture B1, wherein white carbon black is calculated as SiO2: aluminum sulfate 18 hydrate is calculated as Al2O3: water: n-butylamine: 1,3-diphenyltetramethyldisilazane = 1: 0.01: 15: 0.2: 0.05 (molar ratio). B1 is crystallized at 160° C. for 40 h in a sealed container, then centrifuged to obtain a solid, washed the solid with deionized water for multiple times until the pH of the washing liquid reaches 7.0, and then dried the washed solid at 160° C. for 5 hours to obtain molecular sieve C1.

[0072] 100 g of Cl, 10 g of alumina monohydrate, 90 g of 3% nitric acid aqueous solution, 4 g of sesbania powder and 8 g of a polymer mixture (including 3.2 g of starch and 4.8 g of hexadecyltrimethylammonium bromide) were mixed and extruded into a four-leaf clover shape, and then treated at 130°C for 12 hours; 500°C for 5 hours; treated with 3% ammonium acetate solution at 40°C for 3 hours, and exchanged 4 times continuously; treated at 450°C in a saturated water vapor atmosphere for 5 hours; treated with 1.0% oxalic acid solution at 50°C for 6 hours to obtain catalyst D1.

[0073] The XRD spectrum of molecular sieve C1 is as follows Figure 1 As shown, it has typical ZSM-5 molecular sieve diffraction peaks. The SEM photo of molecular sieve C1 is shown in Figure 2 As shown, the b-axis thickness of the molecular sieve is 88nm, and the exposure of the crystal plane perpendicular to the b-axis 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, at 680-760cm -1 There are two strong peaks at the peaks, and the wave numbers corresponding to the peaks are 700 cm -1 and 739cm -1 .

[0074] Through testing, the micropore volume of catalyst D1 is 0.13 cm 3 ·g -1 , the mesopore volume is 0.61cm 3 ·g -1 , mechanical strength is 106N / cm, bulk density is 0.56g·cm -3 .

[0075] [Example 2]

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

[0077] 320.54 g of tetrabutyl silicate, 1.33 g of aluminum sulfate 18hydrate, 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 a mixture A2, wherein tetrabutyl silicate is calculated as SiO2: aluminum sulfate 18hydrate is calculated as Al2O3: water: tetrapropylammonium hydroxide: ethylamine: N-(n-butyl)-3-aminopropyltrimethoxysilane = 1:0.002:5:0.05:0.05:0.02 (molar ratio). Mix 16.39 g of mixture A2, 208.3 g of tetraethyl silicate, 1.33 g of aluminum sulfate 18 water, 180 g of water, 6.01 g of ethylenediamine and 2.25 g of 1,3-dichloro-1,1,3,3-tetraphenyldisilazane to obtain mixture B2, wherein tetraethyl silicate is calculated as SiO2: aluminum sulfate 18 water is calculated as Al2O3: water: ethylenediamine: 1,3-dichloro-1,1,3,3-tetraphenyldisilazane = 1: 0.002: 10: 0.1: 0.005 (molar ratio). B2 is crystallized at 130° C. for 60 h in a sealed container, then centrifuged to obtain a solid, washed the solid with deionized water for multiple times until the pH of the washing liquid reaches 7.0, and then dried the washed solid at 160° C. for 5 hours to obtain molecular sieve C2.

[0078] 100 g of C2, 5 g of alumina monohydrate, 80 g of 1% nitric acid aqueous solution, 3 g of sesbania powder and 5 g of a polymer mixture (including 1.5 g of starch and 3.5 g of hexadecyltrimethylammonium bromide) are mixed and extruded into a cylindrical shape, and then treated at 100°C for 15 hours; treated at 400°C for 10 hours; treated with 1% ammonium chloride solution at 10°C for 5 hours, and exchanged 5 times continuously; treated at 400°C in a saturated water vapor atmosphere for 8 hours; treated with 0.5% hydrochloric acid solution at 10°C for 8 hours to obtain catalyst D2.

[0079] Molecular sieve C2 has a typical ZSM-5 molecular sieve diffraction peak. The b-axis thickness of molecular sieve C2 is 100nm, 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 680-760cm -1 There are two strong peaks at the peaks, and the wave numbers corresponding to the peaks are 700 cm -1 and 740cm -1 .

[0080] Through testing, the micropore volume of catalyst D2 is 0.15cm 3 ·g -1 , the mesopore volume is 0.41cm 3 ·g -1, mechanical strength is 118N / cm, bulk density is 0.51g·cm -3 .

[0081] [Example 3]

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

[0083] 208.3 g of tetrapropyl silicate, 13.33 g of aluminum sulfate 18hydrate, 360 g of water, 42.57 g of piperidine and 52.89 g of N-(2-aminoethyl)-3-aminopropyltriethoxysilane are mixed, and then stirred at 80°C for 6 hours to obtain a mixture A3, wherein tetrapropyl silicate is calculated as SiO2: aluminum sulfate 18hydrate is calculated as Al2O3: water: piperidine: N-(2-aminoethyl)-3-aminopropyltriethoxysilane = 1:0.02:20:0.5:0.2 (molar ratio). 132.87 g of mixture A3, 60 g of silicon powder, 13.33 g of pseudo-boehmite, 450 g of water, 46.48 g of hexamethylenediamine and 51.24 g of 1,3-diphenyltetraethyldisilazane were mixed to obtain mixture B3, wherein silicon powder was calculated as SiO2: pseudo-boehmite was calculated as Al2O3: water: hexamethylenediamine: 1,3-diphenyltetraethyldisilazane = 1: 0.02: 25: 0.4: 0.15 (molar ratio). B3 was crystallized at 180° C. for 10 h in a sealed container, then centrifuged to obtain a solid, washed the solid with deionized water for multiple times until the pH of the washing solution reached 7.0, and then dried the washed solid at 160° C. for 5 hours to obtain molecular sieve C3.

[0084] 100 g of C3, 20 g of alumina monohydrate, 100 g of 5% nitric acid aqueous solution, 5 g of sesbania powder and 10 g of a polymer mixture (including 5 g of starch and 5 g of hexadecyltrimethylammonium bromide) are mixed and extruded into a four-leaf clover shape, and then treated at 150°C for 10 hours; 550°C for 4 hours; treated at 70°C for 2 hours with 5% ammonium nitrate solution, and exchanged three times continuously; treated at 500°C in a saturated water vapor atmosphere for 2 hours; treated at 90°C for 2 hours with 2.0% nitric acid solution to obtain catalyst D3.

[0085] Molecular sieve C3 has a typical ZSM-5 molecular sieve diffraction peak. The b-axis thickness of molecular sieve C3 is 32nm, 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 680-760cm -1 There are two strong peaks at the peaks, and the wave numbers corresponding to the peaks are 700 cm -1 and 740cm -1 .

[0086] Through testing, the micropore volume of catalyst D3 is 0.16cm 3 ·g -1 , the mesopore volume is 0.76 cm 3 ·g -1 , mechanical strength is 65N / cm, bulk density is 0.50g·cm -3 .

[0087] [Comparative Example 1]

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

[0089] 208.3 g of tetraethyl silicate, 6.66 g of aluminum sulfate 18hydrate, 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 a mixture dA1, wherein the molar ratio of tetraethyl silicate in terms of SiO2: the molar ratio of aluminum sulfate 18hydrate in terms of Al2O3: water: tetrapropylammonium hydroxide: N-aminoethyl-3-aminopropylmethyldimethoxysilane was 1:0.01:15:0.3:0.1. 26.6 g of the mixture dA1, 60 g of white carbon, 6.66 g of aluminum sulfate 18hydrate, 270 g of water and 14.63 g of n-butylamine were mixed to obtain a mixture dB1, wherein the molar ratio of white carbon in terms of SiO2: the molar ratio of aluminum sulfate 18hydrate in terms of Al2O3: water: n-butylamine was 1:0.01:15:0.2. dB1 was crystallized at 160° C. for 40 h in a sealed container, and then centrifuged to obtain a solid, which was washed with deionized water for multiple times until the pH of the washing solution reached 7.0, and then the washed solid was dried at 160° C. for 5 hours to obtain the molecular sieve dC1.

[0090] 100 g of dC1, 10 g of alumina monohydrate, 90 g of 3% nitric acid aqueous solution, 4 g of sesbania powder and 8 g of a polymer mixture (including 3.2 g of starch and 4.8 g of hexadecyltrimethylammonium bromide) are mixed and extruded into a four-leaf clover shape, and then treated at 130°C for 12 hours; 500°C for 5 hours; treated with 3% ammonium acetate solution at 40°C for 3 hours, and exchanged 4 times continuously; treated at 450°C in a saturated water vapor atmosphere for 5 hours; treated with 1.0% oxalic acid solution at 50°C for 6 hours to obtain the catalyst dD1.

[0091] The XRD spectrum of molecular sieve dC1 is as follows Figure 4As shown, it has a typical ZSM-5 molecular sieve diffraction peak. The b-axis thickness of molecular sieve dC1 is 185nm, 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 as follows Figure 5 As shown, at 680-760cm -1 There are no two strong peaks.

[0092] Through testing, the micropore volume of catalyst dD1 is 0.11cm 3 ·g -1 , the mesopore volume is 0.53 cm 3 ·g -1 , mechanical strength is 104N / cm, bulk density is 0.55g·cm -3 .

[0093] [Comparative Example 2]

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

[0095] 208.3 g of tetraethyl silicate, 6.66 g of aluminum sulfate 18hydrate, 270 g of water and 61 g of tetrapropylammonium hydroxide were mixed, and then stirred at 70°C for 10 hours to obtain a mixture dA2, wherein tetraethyl silicate was calculated as SiO2: aluminum sulfate 18hydrate was calculated as Al2O3: water: tetrapropylammonium hydroxide = 1: 0.01: 15: 0.3 (molar ratio). 26.6 g of the mixture dA2, 60 g of white carbon, 6.66 g of aluminum sulfate 18hydrate, 270 g of water, 14.63 g of n-butylamine and 14.28 g of 1,3-diphenyltetramethyldisilazane were mixed to obtain a mixture dB2, wherein white carbon was calculated as SiO2: aluminum sulfate 18hydrate was calculated as Al2O3: water: n-butylamine: 1,3-diphenyltetramethyldisilazane = 1: 0.01: 15: 0.2: 0.05 (molar ratio). dB2 was crystallized at 160° C. for 40 h in a sealed container, and then centrifuged to obtain a solid, which was washed with deionized water for multiple times until the pH of the washing solution reached 7.0, and then the washed solid was dried at 160° C. for 5 hours to obtain the molecular sieve dC2.

[0096] 100 g of dC2, 10 g of alumina monohydrate, 90 g of 3% nitric acid aqueous solution, 4 g of sesbania powder and 8 g of a polymer mixture (including 3.2 g of starch and 4.8 g of hexadecyltrimethylammonium bromide) are mixed and extruded into a four-leaf clover shape, and then treated at 130°C for 12 hours; 500°C for 5 hours; treated with 3% ammonium acetate solution at 40°C for 3 hours, and exchanged 4 times continuously; treated at 450°C in a saturated water vapor atmosphere for 5 hours; treated with 1.0% oxalic acid solution at 50°C for 6 hours to obtain the catalyst dD2.

[0097] The XRD spectrum of molecular sieve dC2 has typical ZSM-5 molecular sieve diffraction peaks. The b-axis thickness of molecular sieve dC2 is 160nm, 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 101. The infrared spectrum of molecular sieve dC2 is 680-760cm -1 There are two strong peaks at the peaks, and the wave numbers corresponding to the peaks are 700 cm -1 and 740cm -1 .

[0098] Through testing, the micropore volume of catalyst dD2 is 0.12cm 3 ·g -1 , the mesopore volume is 0.60cm 3 ·g -1 , mechanical strength is 104N / cm, bulk density is 0.56g·cm -3 .

[0099] [Comparative Example 3]

[0100] Compared with Example 1, the only difference is that an equal molar amount of N-aminoethyl-3-aminopropylmethyldimethoxysilane is used to replace 1,3-diphenyltetramethyldisilazane. The specific preparation process of the molecular sieve and the molecular sieve catalyst is as follows:

[0101] 208.3 g of tetraethyl silicate, 6.66 g of aluminum sulfate 18hydrate, 270 g of water, 61 g of tetrapropylammonium hydroxide and 20.64 g of N-aminoethyl-3-aminopropylmethyldimethoxysilane are mixed, and then stirred at 70°C for 10 hours to obtain a mixture dA3, wherein tetraethyl silicate is calculated as SiO2: aluminum sulfate 18hydrate is calculated as Al2O3: water: tetrapropylammonium hydroxide: N-aminoethyl-3-aminopropylmethyldimethoxysilane = 1:0.01:15:0.3:0.1 (molar ratio). 26.6 g of mixture dA3, 60 g of white carbon, 6.66 g of aluminum sulfate 18-hydrate, 270 g of water, 14.63 g of n-butylamine and 10.32 g of N-aminoethyl-3-aminopropylmethyldimethoxysilane were mixed to obtain mixture dB3, wherein white carbon was calculated as SiO2: aluminum sulfate 18-hydrate was calculated as Al2O3: water: n-butylamine: N-aminoethyl-3-aminopropylmethyldimethoxysilane = 1: 0.01: 15: 0.2: 0.05 (molar ratio). dB3 was crystallized at 160° C. for 40 h in a sealed container, then centrifuged to obtain a solid, washed the solid with deionized water for multiple times until the pH of the washing solution reached 7.0, and then dried the washed solid at 160° C. for 5 hours to obtain molecular sieve dC3.

[0102] 100 g of dC3, 10 g of alumina monohydrate, 90 g of 3% nitric acid aqueous solution, 4 g of sesbania powder and 8 g of a polymer mixture (including 3.2 g of starch and 4.8 g of hexadecyltrimethylammonium bromide) are mixed and extruded into a four-leaf clover shape, and then treated at 130°C for 12 hours; 500°C for 5 hours; treated with 3% ammonium acetate solution at 40°C for 3 hours, and exchanged 4 times continuously; treated at 450°C in a saturated water vapor atmosphere for 5 hours; treated with 1.0% oxalic acid solution at 50°C for 6 hours to obtain the catalyst dD3.

[0103] The XRD spectrum of molecular sieve dC3 has typical ZSM-5 molecular sieve diffraction peaks. The b-axis thickness of molecular sieve dC3 is 135nm, 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 101. The infrared spectrum of molecular sieve dC3 is 680-760cm -1 There are no two strong peaks.

[0104] Through testing, the micropore volume of catalyst dD3 is 0.12cm 3 ·g -1 The mesopore volume is 0.59 cm 3 ·g -1 , mechanical strength is 102N / cm, bulk density is 0.57g·cm -3 .

[0105] [Comparative Example 4]

[0106] Compared with Example 1, the only difference is that an equal amount of 1,3-diphenyltetramethyldisilazane is used to replace N-aminoethyl-3-aminopropylmethyldimethoxysilane. The specific preparation process of the molecular sieve and the molecular sieve catalyst is as follows:

[0107] 208.3 g of tetraethyl silicate, 6.66 g of aluminum sulfate 18hydrate, 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 a mixture dA4, wherein tetraethyl silicate is calculated as SiO2: aluminum sulfate 18hydrate is calculated as Al2O3: water: tetrapropylammonium hydroxide: 1,3-diphenyltetramethyldisilazane = 1:0.01:15:0.3:0.1 (molar ratio). 26.6 g of mixture dA4, 60 g of white carbon, 6.66 g of aluminum sulfate 18hydrate, 270 g of water, 14.63 g of n-butylamine and 14.28 g of 1,3-diphenyltetramethyldisilazane were mixed to obtain mixture dB4, wherein white carbon was calculated as SiO2: aluminum sulfate 18hydrate was calculated as Al2O3: water: n-butylamine: 1,3-diphenyltetramethyldisilazane = 1: 0.01: 15: 0.2: 0.05 (molar ratio). dB4 was crystallized at 160° C. for 40 h in a sealed container, then centrifuged to obtain a solid, washed the solid with deionized water for multiple times until the pH of the washing solution reached 7.0, and then dried the washed solid at 160° C. for 5 hours to obtain molecular sieve dC4.

[0108] 100 g of dC4, 10 g of alumina monohydrate, 90 g of 3% nitric acid aqueous solution, 4 g of sesbania powder and 8 g of a polymer mixture (including 3.2 g of starch and 4.8 g of hexadecyltrimethylammonium bromide) are mixed and extruded into a four-leaf clover shape, and then treated at 130°C for 12 hours; 500°C for 5 hours; treated with 3% ammonium acetate solution at 40°C for 3 hours, and exchanged 4 times continuously; treated at 450°C in a saturated water vapor atmosphere for 5 hours; treated with 1.0% oxalic acid solution at 50°C for 6 hours to obtain the catalyst dD4.

[0109] Molecular sieve dC4 has a typical ZSM-5 molecular sieve diffraction peak. The b-axis thickness of molecular sieve dC4 is 142nm, 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 101. The infrared spectrum of molecular sieve dC4 is 680-760cm -1 There are two strong peaks at the peaks, and the wave numbers corresponding to the peaks are 700 cm -1 and 740cm -1 .

[0110] Through testing, the micropore volume of catalyst dD4 is 0.12cm 3 ·g -1 , the mesopore volume is 0.60cm 3 ·g -1 , mechanical strength is 101N / cm, bulk density is 0.56g·cm -3 .

[0111] [Comparative Example 5]

[0112] Compared with Example 1, the only difference 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 18hydrate, 270 g of water and 61 g of tetrapropylammonium hydroxide are mixed, and then stirred at 70°C for 10 hours to obtain a mixture dA5, wherein tetraethyl silicate is calculated as SiO2: aluminum sulfate 18hydrate is calculated as Al2O3: water: tetrapropylammonium hydroxide = 1:0.01:15:0.3 (molar ratio). 26.6 g of mixture dA5, 60 g of white carbon, 6.66 g of aluminum sulfate 18 water, 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 were mixed to obtain mixture dB5, wherein white carbon was calculated as SiO2: aluminum sulfate 18 water was calculated as Al2O3: water: n-butylamine: 1,3-diphenyltetramethyldisilazane = 1: 0.01: 15: 0.2: 0.05 (molar ratio). dB5 was crystallized at 160° C. for 40 h in a sealed container, then centrifuged to obtain a solid, washed the solid with deionized water for multiple times until the pH of the washing solution reached 7.0, and then dried the washed solid at 160° C. for 5 hours to obtain molecular sieve dC5.

[0114] 100 g of dC5, 10 g of alumina monohydrate, 90 g of 3% nitric acid aqueous solution, 4 g of sesbania powder and 8 g of a polymer mixture (including 3.2 g of starch and 4.8 g of hexadecyltrimethylammonium bromide) are mixed and extruded into a four-leaf clover shape, and then treated at 130°C for 12 hours; 500°C for 5 hours; treated with 3% ammonium acetate solution at 40°C for 3 hours, and exchanged 4 times continuously; treated at 450°C in a saturated water vapor atmosphere for 5 hours; treated with 1.0% oxalic acid solution at 50°C for 6 hours to obtain the catalyst dD5.

[0115] Molecular sieve dC5 has a typical ZSM-5 molecular sieve diffraction peak. The b-axis thickness of molecular sieve dC5 is 148nm, 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 101. The infrared spectrum of molecular sieve dC5 is 680-760cm -1 There are two strong peaks at the peaks, and the wave numbers corresponding to the peaks are 700 cm -1 and 740cm -1 .

[0116] Through testing, the micropore volume of catalyst dD5 is 0.12cm 3 ·g -1 , the mesopore volume is 0.60cm 3 ·g -1 , mechanical strength is 103N / cm, bulk density is 0.56g·cm -3 .

[0117] [Examples 4-6]

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

[0121] Table 1 Benzene alkylation to ethylbenzene reaction results

[0122]

[0123]

[0124] The above describes the specific implementation of the present invention in detail, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the various technical features being combined in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A method for preparing a ZSM-5 molecular sieve, comprising: (a) mixing a silicon source I, an aluminum source I, water, a template agent I and an organic matter I, and treating the mixture to obtain a mixture A; (b) mixing mixture A, silicon source II, aluminum source II, water, template II and organic matter II to obtain mixture B; (c) crystallizing the mixture B, performing liquid-solid separation, washing, and drying to obtain the molecular sieve; Wherein, the organic substance I in step (a) is an aminopropyl-containing silane, preferably one or more of N-aminoethyl-3-aminopropylmethyldimethoxysilane, N-(n-butyl)-3-aminopropyltrimethoxysilane or N-(2-aminoethyl)-3-aminopropyltriethoxysilane.

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

3. The preparation method according to claim 1, characterized in that: In step (b), the silicon source II is one or more of silica sol, white carbon black, silicon powder, tetramethyl silicate, tetraethyl silicate, tetrapropyl silicate, and tetrabutyl silicate; and / or, in step (b), the aluminum source II is one or more of aluminum nitrate, aluminum chloride, aluminum sulfate, aluminum isopropoxide, sodium aluminate, and pseudo-boehmite; and / or, in step (b), the template agent II is one or more of tetrapropylammonium bromide, tetrapropylammonium hydroxide, ethylamine, ethylenediamine, n-propylamine, propylenediamine, n-butylamine, butylenediamine, n-hexylamine, hexamethylenediamine, ammonia water, hexamethyleneimine, piperidine, piperazine, and homopiperazine; and / or, in step (b), the organic matter II is a disilazane containing phenyl, preferably one or more of 1,3-diphenyltetramethyldisilazane, 1,3-dichloro-1,1,3,3-tetraphenyldisilazane, or 1,3-diphenyltetraethyldisilazane; Preferably, in step (b), the molar ratios of silicon source II, aluminum source II, water, template II and organic matter II are, respectively, silicon source II: aluminum source II: water: template 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 of silicon source II, aluminum source II, water, template II and organic matter II is (0.04-0.22): 1, wherein the silicon source II and the aluminum source II are calculated as SiO2 and Al2O3, respectively.

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

5. ZSM-5 molecular sieve prepared by the preparation method according to any one of claims 1 to 4.

6. The molecular sieve according to claim 5, characterized in that: The infrared spectrum of the molecular sieve is in the wave number range of 680-760 cm -1 There are two strong peaks.

7. The molecular sieve according to claim 5, characterized in that: The b-axis thickness of the molecular sieve is 20-120 nm, preferably 30-100 nm, and the exposure of the crystal plane perpendicular to the b-axis is 65%-80%, preferably 65%-75%.

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

9. A catalyst for preparing ethylbenzene by alkylation of benzene, characterized in that: The catalyst comprises a ZSM-5 molecular sieve prepared by the preparation method according to any one of claims 1 to 4, and optionally comprises alumina.

10. The catalyst according to claim 9, characterized in that: The catalyst has a molecular sieve content of more than 80%, preferably 80%-90%, and an alumina content of less than 20%, preferably 10%-20%, based on the mass of the catalyst.

11. The catalyst according to claim 9, characterized in that: The micropore volume of the catalyst is 0.11-0.16 cm 3 ·g -1 , the mesopore volume is 0.40-0.80cm 3 ·g -1 , mechanical strength is 60-120N / cm, bulk density is 0.50-0.60g·cm -3 .

12. A method for preparing a catalyst for preparing ethylbenzene by alkylation of benzene, comprising: (d) The ZSM-5 molecular sieve prepared by any one of the methods of claims 1 to 4, alumina and a polymer mixture are mixed and molded, and then dried, calcined, ammonium exchanged, steam treated, and acid washed to obtain the catalyst.

13. The preparation method according to claim 12, characterized in that: The aluminum oxide in step (d) is aluminum oxide monohydrate; and / or, the polymer mixture in step (d) is a mixture of starch and hexadecyltrimethylammonium bromide, wherein the mass ratio of starch to the polymer mixture is 30%-50%; Preferably, 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); Preferably, in step (d), the drying condition is 100-150°C for 10-15 hours; the roasting condition is 400-550°C for 4-10 hours; the steam treatment condition is 400-500°C in a saturated steam atmosphere for 3-8 hours; the pickling condition is 0.5%-2.0% by mass concentration of an acid solution at 10-90°C for 2-8 hours.

14. A method for preparing ethylbenzene by alkylation of benzene, characterized in that: The reaction raw materials benzene and ethylene are contacted with the catalyst described in any one of claims 9-11 or the catalyst prepared by the method described in any one of claims 12-13 to produce ethylbenzene.

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

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