Beta molecular sieve catalyst and preparation and application thereof

Abstract

The invention discloses a Beta molecular sieve catalyst as well as a preparation method and application thereof. The catalyst comprises a Beta molecular sieve connected with double silicon groups, the static water initial contact angle of the catalyst is 140-165 degrees, and the static water adsorption capacity is 130-170mg / g. When the catalyst is used for the reaction of preparing alkyl aromatic hydrocarbon through alkylation of aromatic hydrocarbon and olefin, the catalyst has good activity and alkyl aromatic hydrocarbon selectivity, and also has good water resistance and alkaline impurity resistance.

Description

Technical Field

[0001] This invention relates to the technical field of aromatic alkylation catalysts, specifically to a Beta molecular sieve catalyst, its preparation, and its application in the alkylation of aromatics and olefins. Background Technology

[0002] Aromatic hydrocarbons are important basic organic raw materials with a wide range of applications and play a vital role in the development of the national economy. In particular, ethylbenzene is mainly used downstream to produce styrene, which is then used as a raw material monomer to synthesize high molecular compounds such as polystyrene, styrene-butadiene rubber, ABS, and SBS, which are widely used in urban construction, electronic equipment, and aerospace.

[0003] Ethylbenzene is mainly produced by the alkylation reaction of benzene and ethylene under the action of an acidic molecular sieve catalyst. Beta molecular sieves have a three-dimensional twelve-membered ring pore structure, possess suitable acidity and good hydrothermal stability, and are widely used in industrial benzene and ethylene alkylation reaction equipment to produce ethylbenzene. CN202111128952.8 discloses a Beta molecular sieve catalyst with a crystallite size of 50-200 nm, possessing a microporous-mesoporous hierarchical pore structure and a core-shell structure, and exhibiting a high mesoporous volume ratio, used in the industrial production of ethylbenzene from benzene and ethylene via liquid-phase alkylation. CN201110217406.1 discloses a Beta molecular sieve catalyst with a Beta molecular sieve content of 10%-80%, an antimony oxide content of 0.1%-10%, and a rare earth metal oxide content of 1%-20%, and the molecular sieve is phosphorus-modified. This catalyst is used in the alkylation reaction of benzene and dilute ethylene to produce ethylbenzene. CN202111006082.7 discloses a Beta molecular sieve catalyst, wherein the Beta molecular sieve... 27 In the Al NMR spectrum, the ratio of the characteristic peak area with a chemical shift of 56-60 ppm to the characteristic peak area with a chemical shift of -5-0 ppm is ≥5. The catalyst is used in the liquid-phase alkylation reaction of benzene and ethylene to produce ethylbenzene.

[0004] In actual industrial production, if the benzene or ethylene raw materials contain water or alkaline impurities, it will seriously affect the performance of the catalyst and affect normal production. Specifically: First, if the industrial raw materials benzene or ethylene contain water impurities, and if the catalyst does not have good water resistance, water molecules will easily compete with benzene or ethylene molecules for adsorption at the acidic active sites of the catalyst during the reaction, leading to a decrease in catalytic performance. Second, if the industrial raw materials benzene or ethylene contain alkaline substances, these substances will easily react with the acidic active sites of the catalyst during the reaction, leading to rapid alkaline poisoning and deactivation of the catalyst.

[0005] Existing technologies focus on developing Beta molecular sieve catalysts with high activity or high selectivity, but have not adequately addressed the catalysts' resistance to water and alkaline impurities. Therefore, in order to ensure the normal production of industrial plants that produce ethylbenzene from benzene and ethylene alkylation, it is crucial to develop Beta molecular sieve catalysts with good resistance to water and alkaline impurities. Summary of the Invention

[0006] This invention provides a Beta molecular sieve catalyst, its preparation, and its application. When used in the alkylation of aromatics with olefins to prepare alkyl aromatics, the catalyst exhibits not only good activity and selectivity for alkyl aromatics, but also excellent resistance to water and alkaline impurities.

[0007] The first aspect of the present invention provides a Beta molecular sieve catalyst, comprising a Beta molecular sieve connected with dual silicon groups, wherein the catalyst has a static water initial contact angle of 140-165° and a static water adsorption capacity of 130-170 mg / g.

[0008] In one embodiment of the above technical solution, the initial contact angle of the static water is, for example, 145°, 152°, 157°, 160°, and / or the static water adsorption capacity is, for example, 135 mg / g, 140 mg / g, 145 mg / g, 150 mg / g, 154 mg / g, 160 mg / g, 165 mg / g.

[0009] In one embodiment of the above technical solution, the Beta molecular sieve catalyst is a binder-free molecular sieve catalyst.

[0010] In one embodiment of the above technical solution, the mass content of the molecular sieve is 95%-98%, for example 97%, based on the mass of the catalyst, and / or the mass content of the disilicon groups, calculated as silicon oxide, is 2%-5% based on the mass of the catalyst.

[0011] In the above technical solution, a bissilicon group refers to an organic group containing two silicon atoms. The preferred structural formula of the bissilicon group is... and / or X1-X12 represent the positions connected to the Beta molecular sieve, and the Beta molecular sieve is connected through one or more of the X1-X12 positions.

[0012] In the above technical solution, preferably, the Beta molecular sieve in the Beta molecular sieve catalyst has a particulate morphology and a crystal size of 5-20 nm, for example 5-12 nm, 15-18 nm or 16-20 nm.

[0013] In the above technical solution, preferably, the SiO2 / Al2O3 molar ratio of the molecular sieve in the catalyst is 16-50, for example 20-40, and more specifically, for example 25.

[0014] In the above technical solution, preferably, the specific surface area of ​​the catalyst is 550-650 m². 2 / g, for example 600-630m 2 / g.

[0015] In the above technical solution, preferably, the micropore volume of the catalyst is 0.18-0.21 cm³. 3 / g, for example 0.20cm 3 / g.

[0016] A second aspect of this invention provides a method for preparing the above-mentioned Beta molecular sieve catalyst, comprising the following steps:

[0017] a) The molecular sieve raw powder, the first aromatic hydrocarbon and the first modifier are brought into contact and dried to obtain the modified molecular sieve raw powder;

[0018] b) The modified molecular sieve powder, silicon source, aluminum source, and silica sol are mixed, shaped, and dried to obtain the catalyst preform;

[0019] c) The catalyst preform and the template agent solution are brought into contact to obtain a mixture;

[0020] d) Processing the mixture to obtain a catalyst precursor, wherein the processing may include closed heating, calcination and ammonium exchange;

[0021] e) Contact the catalyst precursor and the pore-forming liquid, and process them to obtain a modified catalyst precursor, wherein the processing may include closed heating and calcination.

[0022] f) The modified catalyst precursor, the second aromatic hydrocarbon, and the second modifier are contacted and treated to obtain the catalyst; wherein the treatment includes closed heating, washing, and drying.

[0023] The first modifier is different from the second modifier.

[0024] In the above technical solution, preferably, step a) includes one or more of the following features:

[0025] The molecular sieve in the molecular sieve raw powder is a Beta molecular sieve.

[0026] The SiO2 / Al2O3 molar ratio of the molecular sieve raw powder is 16-50, for example 20-40, more specifically for example 25;

[0027] The first aromatic hydrocarbon is selected from at least one of benzene, ethylbenzene, and toluene;

[0028] The first modifier is a silazane, which is preferably selected from at least one of hexamethyldisilazane, hexamethyldisilaurea, N,O-bistrimethoxyalkylacetamide and tetramethyldivinyldisilazane;

[0029] The mass ratio of the molecular sieve raw powder, the first aromatic hydrocarbon, and the first modifier is 1:(1.5-10):(0.05-0.2), for example, 1:(3-8):(0.07-0.15);

[0030] The contact process involves mixing and stirring the first aromatic hydrocarbon and the first modifier at 10-40°C for 5-30 minutes, then adding the second molecular sieve powder, and allowing it to stand or stir at 90-130°C for 60-120 minutes.

[0031] In the above technical solution, the drying in step a) can be carried out using conventional methods, such as the following drying conditions: drying temperature of 100-150℃ and drying time of 5-10 hours.

[0032] In the above technical solution, preferably, step b) includes one or more of the following features:

[0033] The aluminum source is selected from at least one of aluminum chloride, aluminum nitrate, aluminum sulfate, aluminum isopropoxide, boehmite, aluminum hydroxide, and sodium aluminate;

[0034] The silicon source is selected from silicon powder, and the particle size of the silicon powder is preferably 10nm-2000nm, for example 200nm;

[0035] The silica sol is an alkaline silica sol, preferably a sodium-type silica sol and / or an ammonium-type silica sol;

[0036] The silica sol contains 35%-60% by mass, for example, 40% or 50%;

[0037] The modified molecular sieve powder, silicon source, and silica sol are all calculated as SiO2, and the aluminum source is calculated as Al2O3. The molar ratio of the modified molecular sieve powder, silicon source, silica sol, and aluminum source is (0.1-0.5):1:(1.0-2.5):(0.04-0.22), for example (0.2-0.4):1:(1.3-2.0):(0.08-0.20). The preferred molar ratio of the total SiO2 in the silicon source and silica sol to the Al2O3 in the aluminum source is 16-50:1.

[0038] In the above technical solution, there are no strict limitations on the specific molding method of step b). The catalyst molding method commonly used in the art can be adopted, such as extrusion molding.

[0039] In the above technical solution, in step b), the catalyst preform can be made into various shapes as needed, such as strips, with cross-sections that can be circular, gear-shaped, clover-shaped, four-leaf clover-shaped, or honeycomb-shaped. In a preferred embodiment, the diameter of the catalyst preform is 1.0-3.0 mm and the length is 2-10 mm.

[0040] In the above technical solution, in step b), the drying can be carried out using conventional methods, such as the following conditions: drying temperature of 100-150℃ and drying time of 5-10 hours.

[0041] In the above technical solution, preferably, step c) includes one or more of the following features:

[0042] The template agent solution is selected from at least one of tetraethylammonium hydroxide aqueous solution, tetraethylammonium bromide aqueous solution, trimethylcyclohexylammonium hydroxide aqueous solution, and dimethylethylcyclohexylammonium hydroxide aqueous solution;

[0043] The mass concentration of the template agent solution is 6%-15%, for example 10% or 12%;

[0044] The mass ratio of the catalyst preform to the template agent solution is 1:(1-1.5), for example, 1:1.2.

[0045] In the above technical solution, preferably, in step d), the closed heating treatment includes placing or stirring the mixture in a closed space at 140-170℃ for 36-96 hours. In step d), after the closed heating treatment and before calcination, conventional steps such as washing and drying may be included. The washing and drying can be carried out using conventional methods. For example, washing can be performed under the following conditions: washing with deionized water until the pH of the solution is 7-7.5; drying can be performed under the following conditions: drying temperature of 100-150℃ and drying time of 5-10 hours. The calcination can be carried out using conventional methods. For example, calcination can be performed under the following conditions: calcination temperature of 520-580℃ and calcination time of 4-8 hours. The ammonium exchange can be carried out using conventional methods. For example, ammonium exchange can be performed under the following conditions: temperature of 20-70℃ and time of 1-5 hours. The ammonium salt can be at least one of ammonium chloride, ammonium sulfate, ammonium oxalate, and ammonium nitrate, and the mass concentration of the ammonium salt solution can be 1%-10%.

[0046] In the above technical solution, preferably, step e) includes one or more of the following features:

[0047] The pore-forming solution is an aqueous solution of tetraethylammonium hydroxide or a mixed aqueous solution of tetraethylammonium hydroxide and tetraethylammonium bromide, and the mass concentration of the pore-forming solution is preferably 5%-15%.

[0048] The mass ratio of the catalyst precursor to the pore-forming liquid is 1:(1.5-2), for example, 1:1.7.

[0049] In the above technical solution, preferably, the closed heating treatment in step e) includes standing or stirring the catalyst precursor and pore-forming solution at 160-180℃ for 24-96 hours. In step e), after the closed heating treatment and before calcination, conventional steps such as washing and drying may be included. The washing and drying can be performed using conventional methods; for example, washing can be performed under the following conditions: washing with deionized water until the pH of the solution is 7-7.5; drying can be performed under the following conditions: drying temperature of 100-150℃ and drying time of 5-10 hours. The calcination can be performed using conventional methods; for example, calcination can be performed under the following conditions: calcination temperature of 520-580℃ and calcination time of 4-8 hours.

[0050] In the above technical solution, preferably, step f) includes one or more of the following features:

[0051] The second aromatic hydrocarbon is selected from at least one of benzene, ethylbenzene, and toluene;

[0052] The second modifier is a bissilane, and the preferred structural formula of the bissilane is... and / or R1-R12 are each independently selected from C1-C6 alkoxy and C1-C6 alkoxy-C1-C6 alkyl, preferably each independently being methoxy, ethoxy or 3-methoxypropyl; preferably, the bissilane is selected from at least one of bis[(3-triethoxysilyl)propyl]amine, bis[(3-trimethoxysilyl)propyl]amine and 1,2-bis(triethoxysilyl)ethane;

[0053] The mass ratio of the modified catalyst precursor, the second aromatic hydrocarbon, and the second modifier is 1:(1.5-5.0):(0.1-0.5), for example, 1:(2-4.0):(0.2-0.4).

[0054] In the above technical solution, preferably, the sealed heating treatment in step f) includes mixing and stirring the second aromatic hydrocarbon and the second modifier at 20-80°C for 10-30 minutes, then adding the modified catalyst precursor, and allowing it to stand or stir at 100-140°C for 30-60 minutes, followed by washing and drying. The washing and drying can be carried out using conventional methods. For example, the washing conditions can be as follows: repeated washing with a large amount of ethanol; the drying conditions can be as follows: drying temperature of 100-150°C, drying time of 5-10 hours.

[0055] A third aspect of the present invention provides a method for alkylating aromatics and olefins, wherein the reactants, aromatics and olefins, are contacted with the above-mentioned Beta molecular sieve catalyst to undergo an alkylation reaction to obtain alkyl aromatics.

[0056] In the above technical solution, preferably, the aromatic hydrocarbon is selected from at least one of benzene and alkylbenzene, and more preferably from at least one of benzene, toluene, ethylbenzene, propylbenzene and butylbenzene; preferably, the olefin is selected from C2-C6 olefins, and more preferably from at least one of ethylene, propylene and butene, wherein the olefin can be a pure olefin or a mixture with other non-olefin gases, and the volume concentration of the olefin is preferably 10%-100%.

[0057] In the above technical solution, preferably, the alkylation reaction conditions include: a reaction temperature of 120-250℃, a reaction pressure of 2.0-5.0 MPa, and an olefin mass hourly space velocity of 0.5-3.0 h⁻¹. -1 The molar ratio of aromatics to olefins is 1.0-3.0.

[0058] Compared with the prior art, the present invention has the following beneficial effects:

[0059] 1. The inventors of this invention have discovered that the catalyst can be a binder-free Beta molecular sieve catalyst, comprising a Beta molecular sieve linked with dual silicon groups, and that the catalyst's initial static water contact angle and static water adsorption capacity are within a specific range, wherein the initial static water contact angle is 140-165° and the static water adsorption capacity is 130-170 mg / g. The catalyst with the above characteristics not only exhibits good activity and selectivity in the liquid-phase alkylation reaction of benzene and ethylene to ethylbenzene, but also good resistance to water and alkaline impurities. If the industrial raw material benzene or ethylene contains alkaline substances, using the above catalyst can ensure long-term stable operation of the equipment. Furthermore, the molecular sieve in the catalyst of this invention can be 5-20 nm small crystallites with a suitable pore structure, further enhancing its good activity and selectivity.

[0060] 2. In the catalyst preparation process of this invention, a first modifier and a second modifier are used for stepwise modification treatment. The first modifier treatment helps to inhibit the growth of Beta molecular sieve crystal size, resulting in a binder-free Beta molecular sieve catalyst with ultra-small crystal size of only 5-20 nm, which can further improve the activity and selectivity of the catalyst. The second modifier treatment allows the outer surface of the second catalyst to retain specific bissilane modified components, which are beneficial for water resistance during the reaction process and also facilitate the rapid adsorption of alkaline impurities, thereby improving the overall anti-toxicity of the catalyst.

[0061] 3. The catalyst of this invention is particularly suitable for olefins with a volume concentration of 10-100%. Taking ethylene feedstock as an example, the feedstock can be pure ethylene, tail gas from FCC or DCC units with low ethylene concentration, or mixed C2 with high ethylene concentration, thus fully expanding the sources of ethylene feedstock and creating more economic benefits. Attached Figure Description

[0062] Figure 1 The XRD pattern of the Beta molecular sieve catalyst prepared in Example 1 of this invention;

[0063] Figure 2 This is a static water contact angle test photograph of the Beta molecular sieve catalyst prepared in Example 1 of the present invention;

[0064] Figure 3 This is a TEM image of the Beta molecular sieve catalyst prepared in Example 1 of the present invention. Detailed Implementation

[0065] 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.

[0066] In this invention, the XRD pattern of the catalyst was obtained using a Bruker D8 ADVANCE X-ray powder diffractometer (Germany). The voltage was set to 40 kV, the current to 40 mA, and the scan rate to 0.3°·min. -1 .

[0067] In this invention, the static water initial contact angle of the molecular sieve is measured using the Chengde Dingsheng JY-82C video contact angle measuring instrument. An appropriate amount of ground powder sample is placed in a tablet press and pressed into a tablet shape, then placed on the contact angle testing platform. Water droplets are added using the automatic titration system of the equipment, test photos are taken, and then the contact angle is measured using the protractor method.

[0068] In this invention, the static water adsorption capacity is tested using a BSD-VVS multi-station gravimetric gas vapor adsorption instrument from Best Instruments Technology Co., Ltd. Before the test, the sample is activated at 200°C for 6 hours under vacuum conditions. The cumulative water adsorption capacity of the sample when the relative pressure P / P0 is 0.90 is taken as the final static water adsorption capacity.

[0069] In this invention, SEM images were obtained using a Hitachi S-4800 cold field emission high-resolution scanning electron microscope manufactured by Hitachi Corporation.

[0070] In this invention, TEM images were obtained using a Tecnai G220 S-TWIN transmission electron microscope.

[0071] In this invention, the nitrogen adsorption-desorption isotherm of the catalyst was tested at liquid nitrogen temperature using a BEL-MAX specific surface area and pore size analyzer manufactured by BELSORP Corporation of Japan. The specific surface area was calculated using the BET equation, and the micropore volume was calculated using the t-plot method.

[0072] 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.

[0073]

Example 1

[0074] This embodiment is used to prepare a Beta molecular sieve catalyst, and the specific preparation process is as follows:

[0075] 500 g of toluene and 10 g of N,O-bistrimethoxyalkylacetamide were mixed and stirred at 20 °C for 20 minutes. Then, 100 g of Beta molecular sieve (SiO2 / Al2O3 molar ratio of 25) was added and allowed to stand at 110 °C for 80 minutes. Finally, the mixture was dried at 140 °C for 6 hours to obtain modified molecular sieve powder A1. The mass ratio of molecular sieve powder, first aromatic hydrocarbon and first modifier was 1:5:0.1. Then, 18 g of modified molecular sieve powder A1, 60 g of silica powder (particle size 200 nm), 225 g of sodium silicate sol aqueous solution with a mass content of 40%, and 25.5 g of sodium aluminate (Al2O3 mass content 40%) were mixed evenly, wherein the molar ratio of modified molecular sieve powder, silica powder, silica sol, and aluminum source was 0.3:1:1.5:0.1. The mixture was then extruded and dried to obtain a strip-shaped catalyst preform B1 with a diameter of 1.5 mm, a length of 3-8 mm, and a clover-shaped cross-section. Then, 100 g of catalyst preform B1 was immersed in 120 g of tetraethylammonium hydroxide aqueous solution (mass concentration 10%) to obtain mixture C1. Mixture C1 was allowed to stand in a sealed space at 150°C for 50 hours, then washed with deionized water until the pH of the solution reached 7.5. It was then dried at 120°C for 8 hours, calcined at 560°C for 6 hours, and finally exchanged with a 7% ammonium sulfate solution at 55°C for 2 hours to obtain catalyst precursor D1. 100 g of catalyst precursor D1 and 170 g of tetraethylammonium hydroxide aqueous solution (10% mass concentration) were mixed thoroughly and allowed to stand at 170°C for 48 hours. The mixture was then washed with deionized water until the pH of the solution reached 7.0, dried at 150°C for 6 hours, and calcined at 550°C for 5 hours to obtain modified catalyst precursor E1. 300 g of ethylbenzene and 30 g of bis[(3-triethoxysilyl)propyl]amine were mixed and stirred at 60 °C for 15 minutes. Then, 100 g of modified catalyst precursor E1 was added and allowed to stand at 120 °C for 50 minutes. The mass ratio of modified catalyst precursor, second aromatic hydrocarbon and second modifier was 1:3:0.3. The mixture was then repeatedly washed with a large amount of ethanol and dried at 140 °C for 7 hours to obtain catalyst F1.

[0076] The characterization results of catalyst F1 are as follows: XRD pattern as shown. Figure 1 As shown, it exhibits characteristic diffraction peaks typical of Beta molecular sieves; static water contact angle test photographs are shown below. Figure 2 As shown, the value is 152°; the mass content of Beta molecular sieve in the catalyst is 97.0%; the static water adsorption capacity is 154 mg / g; the SiO2 / Al2O3 molar ratio is 25; and the specific surface area of ​​the catalyst is 602 m². 2 / g, micropore volume is 0.19cm³ 3 / g. TEM image of catalyst F1 as shown Figure 3As shown, the Beta molecular sieve has a granular morphology with a grain size of 15-18 nm.

[0077]

Example 2

[0078] This embodiment is used to prepare a Beta molecular sieve catalyst, and the specific preparation process is as follows:

[0079] 1000g of toluene and 20g of tetramethyldivinyldisilazane were mixed and stirred at 40°C for 5 minutes. Then, 100g of Beta molecular sieve (SiO2 / Al2O3 molar ratio of 16) was added and allowed to stand at 130°C for 60 minutes. Finally, the mixture was dried at 150°C for 5 hours to obtain modified molecular sieve powder A2. The mass ratio of molecular sieve powder, first aromatic hydrocarbon and first modifier was 1:10:0.2. Then, 30 g of modified molecular sieve powder A2, 60 g of silica powder (particle size 200 nm), 250 g of ammonium silica sol aqueous solution with a mass content of 60%, and 56.1 g of sodium aluminate (Al2O3 mass content 40%) were mixed evenly, wherein the molar ratio of modified molecular sieve powder, silica powder, silica sol, and aluminum source was 0.5:1:2.5:0.22. The mixture was then extruded and dried to obtain a strip-shaped catalyst preform B2 with a diameter of 3 mm, a length of 2-10 mm, and a clover-shaped cross-section. Then, 100 g of catalyst preform B2 was immersed in a mixed aqueous solution of 150 g of tetraethylammonium hydroxide and tetraethylammonium bromide (mass concentration 15%, containing 15 g of tetraethylammonium hydroxide and 7.5 g of tetraethylammonium bromide) to obtain mixture C2. Mixture C2 was allowed to stand in a sealed space at 170°C for 36 hours, then washed with deionized water until the pH of the solution was 7. It was then dried at 150°C for 5 hours, calcined at 580°C for 4 hours, and finally exchanged with a 10% ammonium sulfate solution at 70°C for 1 hour to obtain catalyst precursor D2. 100 g of catalyst precursor D2 was mixed with 200 g of a 15% aqueous solution of tetraethylammonium hydroxide and tetraethylammonium bromide (containing 15 g of each). The mixture was allowed to stand at 180°C for 24 hours, then washed with deionized water until the pH of the solution was 7.0. It was then dried at 150°C for 10 hours and calcined at 580°C for 4 hours to obtain modified catalyst precursor E2. 500 g of benzene and 50 g of 1,2-bis(triethoxysilyl)ethane were mixed and stirred at 80 °C for 10 minutes. Then, 100 g of modified catalyst precursor E2 was added and allowed to stand at 140 °C for 30 minutes. The mass ratio of modified catalyst precursor, second aromatic hydrocarbon and second modifier was 1:5:0.5. The mixture was then repeatedly washed with a large amount of ethanol and dried at 150 °C for 5 hours to obtain catalyst F2.

[0080] The characterization results of catalyst F2 are as follows: the XRD pattern shows typical diffraction peaks of Beta molecular sieves; the static water contact angle is 160°; the mass content of Beta molecular sieves in the catalyst is 95.0%; the static water adsorption capacity is 130 mg / g; the SiO2 / Al2O3 molar ratio is 16; and the specific surface area of ​​the catalyst is 648 m². 2 / g, micropore volume is 0.21cm³ 3 / g. TEM images of catalyst F2 show that the Beta molecular sieve has a particulate morphology with a grain size of 5-12 nm.

[0081]

Example 3

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

[0083] 150 g of toluene and 5 g of hexamethyldisilamide were mixed and stirred at 10 °C for 30 minutes. Then, 100 g of Beta molecular sieve (SiO2 / Al2O3 molar ratio of 50) was added and allowed to stand at 90 °C for 120 minutes. Finally, the mixture was dried at 100 °C for 10 hours to obtain modified molecular sieve powder A3. The mass ratio of molecular sieve powder, first aromatic hydrocarbon and first modifier was 1:1.5:0.05. Then, 6 g of modified molecular sieve powder A3, 60 g of silica powder (particle size 200 nm), 120 g of sodium silicate sol aqueous solution with a mass content of 50%, and 10.2 g of sodium aluminate (Al2O3 mass content 40%) were mixed evenly, wherein the molar ratio of modified molecular sieve powder, silica powder, silica sol, and aluminum source was 0.1:1:1:0.04. The mixture was then extruded and dried to obtain a strip-shaped catalyst preform B3 with a diameter of 2 mm, a length of 2-10 mm, and a clover-shaped cross-section. Then, 100 g of catalyst preform B3 was immersed in 100 g of tetraethylammonium hydroxide aqueous solution (mass concentration 6%) to obtain mixture C3. Mixture C3 was allowed to stand in a sealed space at 140°C for 96 hours, then washed with deionized water until the pH of the solution was 7, dried at 100°C for 10 hours, calcined at 520°C for 8 hours, and finally exchanged with a 1% ammonium nitrate solution at 20°C for 5 hours to obtain catalyst precursor D3. 100 g of catalyst precursor D3 and 150 g of tetraethylammonium hydroxide aqueous solution (5% by mass) were mixed evenly, allowed to stand at 160°C for 96 hours, then washed with deionized water until the pH of the solution was 7.0, dried at 100°C for 10 hours, and calcined at 520°C for 8 hours to obtain modified catalyst precursor E3. 150 g of toluene and 10 g of bis[(3-trimethoxysilyl)propyl]amine were mixed and stirred at 20 °C for 30 minutes. Then, 100 g of modified catalyst precursor E3 was added and allowed to stand at 100 °C for 60 minutes. The mass ratio of modified catalyst precursor, second aromatic hydrocarbon and second modifier was 1:1.5:0.1. The mixture was then washed repeatedly with a large amount of ethanol and dried at 100 °C for 10 hours to obtain catalyst F3.

[0084] The characterization results of catalyst F3 are as follows: the XRD pattern shows typical diffraction peaks of Beta zeolite; the static water contact angle is 140°; the mass content of Beta zeolite in the catalyst is 98.0%; the static water adsorption capacity is 170 mg / g; the SiO2 / Al2O3 molar ratio is 50; and the specific surface area of ​​the catalyst is 551 m². 2 / g, micropore volume is 0.18cm³ 3 / g. TEM images of catalyst F3 show that the Beta molecular sieve has a particulate morphology with a grain size of 16-20 nm.

[0085] Comparative Example 1

[0086] The only difference from Example 1 is that the first modifier N,O-bistrimethoxyalkylacetamide was not added during the catalyst preparation process. The specific preparation process of the catalyst is as follows:

[0087] 500 g of toluene was mixed and stirred at 20 °C for 20 minutes, then 100 g of Beta molecular sieve (SiO2 / Al2O3 molar ratio of 25) was added and allowed to stand at 110 °C for 80 minutes, and then dried at 140 °C for 6 hours to obtain molecular sieve raw powder A4. Then, 18 g of modified molecular sieve raw powder A4, 60 g of silicon powder (particle size of 200 nm), 225 g of sodium silicate sol aqueous solution with a mass content of 40% and 25.5 g of sodium aluminate (Al2O3 mass content of 40%) were mixed evenly, wherein the molar ratio of modified molecular sieve raw powder, silicon powder, silica sol and aluminum source was 0.3:1:1.5:0.1; then, through extrusion molding and drying steps, a strip-shaped catalyst preform B4 with a diameter of 1.5 mm, a length of 3-8 mm and a cross-section of four-leaf clover shape was obtained. Then, 100 g of catalyst precursor B4 was immersed in 120 g of tetraethylammonium hydroxide aqueous solution (mass concentration 10%) to obtain mixture C4. Mixture C4 was allowed to stand in a sealed space at 150 °C for 50 hours, then washed with deionized water until the pH of the solution was 7.5, dried at 120 °C for 8 hours, calcined at 560 °C for 6 hours, and finally exchanged with a 7% ammonium sulfate solution at 55 °C for 2 hours to obtain catalyst precursor D4. 100 g of catalyst precursor D4 and 170 g of tetraethylammonium hydroxide aqueous solution (mass concentration 10%) were mixed evenly, allowed to stand at 170 °C for 48 hours, then washed with deionized water until the pH of the solution was 7.0, dried at 150 °C for 6 hours, and calcined at 550 °C for 5 hours to obtain modified catalyst precursor E4. 300 g of ethylbenzene and 30 g of bis[(3-triethoxysilyl)propyl]amine were mixed and stirred at 60 °C for 15 minutes. Then, 100 g of modified catalyst precursor E4 was added and allowed to stand at 120 °C for 50 minutes. The mass ratio of modified catalyst precursor, second aromatic hydrocarbon and second modifier was 1:3:0.3. The mixture was then repeatedly washed with a large amount of ethanol and dried at 140 °C for 7 hours to obtain catalyst F4.

[0088] The characterization results of catalyst F4 are as follows: the XRD pattern shows typical diffraction peaks characteristic of Beta zeolite; the static water contact angle is 131°; the mass content of Beta zeolite in the catalyst is 97.5%; the static water adsorption capacity is 184 mg / g; the SiO2 / Al2O3 molar ratio is 25; and the specific surface area of ​​the catalyst is 508 m². 2 / g, micropore volume is 0.20cm³ 3 / g. TEM images of catalyst F4 show that the Beta molecular sieve has a particulate morphology with a grain size of 36-55 nm.

[0089] Comparative Example 2

[0090] The only difference from Example 1 is that the second modifier, bis[(3-triethoxysilyl)propyl]amine, was not added during the catalyst preparation process. The specific preparation process of the catalyst is as follows:

[0091] 500 g of toluene and 10 g of N,O-bistrimethoxyalkylacetamide were mixed and stirred at 20 °C for 20 minutes. Then, 100 g of Beta molecular sieve (SiO2 / Al2O3 molar ratio of 25) was added and allowed to stand at 110 °C for 80 minutes. Finally, the mixture was dried at 140 °C for 6 hours to obtain modified molecular sieve powder A5. The mass ratio of molecular sieve powder, first aromatic hydrocarbon and first modifier was 1:5:0.1. Then, 18 g of modified molecular sieve powder A5, 60 g of silica powder (particle size 200 nm), 225 g of sodium silicate sol aqueous solution with a mass content of 40%, and 25.5 g of sodium aluminate (Al2O3 mass content 40%) were mixed evenly, wherein the molar ratio of modified molecular sieve powder, silica powder silica sol, and aluminum source was 0.3:1:1.5:0.1. The mixture was then extruded and dried to obtain a strip-shaped catalyst preform B5 with a diameter of 1.5 mm, a length of 3-8 mm, and a clover-shaped cross-section. Then, 100 g of catalyst preform B5 was immersed in 120 g of tetraethylammonium hydroxide aqueous solution (mass concentration 10%) to obtain mixture C5. Mixture C5 was allowed to stand in a sealed space at 150°C for 50 hours, then washed with deionized water until the pH of the solution reached 7.5. It was then dried at 120°C for 8 hours, calcined at 560°C for 6 hours, and finally exchanged with a 7% ammonium sulfate solution at 55°C for 2 hours to obtain catalyst precursor D5. 100 g of catalyst precursor D5 and 170 g of tetraethylammonium hydroxide aqueous solution (10% mass concentration) were mixed thoroughly and allowed to stand at 170°C for 48 hours. The mixture was then washed with deionized water until the pH of the solution reached 7.0, dried at 150°C for 6 hours, and calcined at 550°C for 5 hours to obtain modified catalyst precursor E5. 300 g of ethylbenzene was stirred at 60°C for 15 minutes, then 100 g of modified catalyst precursor E5 was added and allowed to stand at 120°C for 50 minutes. The mixture was then repeatedly washed with a large amount of ethanol and dried at 140°C for 7 hours to obtain catalyst F5.

[0092] The characterization results of catalyst F5 are as follows: the XRD pattern shows typical diffraction peaks of Beta zeolite; the static water contact angle is 36°; the mass content of Beta zeolite in the catalyst is 99.0%; the static water adsorption capacity is 201 mg / g; the SiO2 / Al2O3 molar ratio is 25; and the specific surface area of ​​the catalyst is 626 m². 2 / g, micropore volume is 0.20cm³ 3 / g. The TEM image of catalyst F5 shows that the Beta molecular sieve has a granular morphology with a grain size of 15-18 nm.

[0093] Comparative Example 3

[0094] The only difference from Example 1 is that an equal mass of the second modifier bis[(3-triethoxysilyl)propyl]amine is used to replace the first modifier N,O-bistrimethoxyalkylacetamide in the catalyst preparation process. The specific preparation process of the catalyst is as follows:

[0095] 500 g of toluene and 10 g of bis[(3-triethoxysilyl)propyl]amine were mixed and stirred at 20 °C for 20 minutes. Then, 100 g of Beta molecular sieve (SiO2 / Al2O3 molar ratio of 25) was added and allowed to stand at 110 °C for 80 minutes. The mixture was then dried at 140 °C for 6 hours to obtain modified molecular sieve powder A6. Next, 18 g of modified molecular sieve powder A6, 60 g of silicon powder (particle size of 200 nm), 225 g of a 40% sodium silicate sol aqueous solution, and 25.5 g of sodium aluminate (Al2O3 mass content of 40%) were mixed evenly. The molar ratio of modified molecular sieve powder, silicon powder, silica sol, and aluminum source was 0.3:1:1.5:0.1. The mixture was then extruded and dried to obtain a strip-shaped catalyst preform B6 with a diameter of 1.5 mm, a length of 3-8 mm, and a clover-shaped cross-section. Then, 100 g of catalyst precursor B6 was immersed in 120 g of tetraethylammonium hydroxide aqueous solution (mass concentration 10%) to obtain mixture C6. Mixture C6 was allowed to stand in a sealed space at 150 °C for 50 hours, then washed with deionized water until the pH of the solution was 7.5, dried at 120 °C for 8 hours, calcined at 560 °C for 6 hours, and finally exchanged with a 7% ammonium sulfate solution at 55 °C for 2 hours to obtain catalyst precursor D6. 100 g of catalyst precursor D6 and 170 g of tetraethylammonium hydroxide aqueous solution (mass concentration 10%) were mixed evenly, allowed to stand at 170 °C for 48 hours, then washed with deionized water until the pH of the solution was 7.0, dried at 150 °C for 6 hours, and calcined at 550 °C for 5 hours to obtain modified catalyst precursor E6. 300 g of ethylbenzene and 30 g of bis[(3-triethoxysilyl)propyl]amine were mixed and stirred at 60 °C for 15 minutes. Then, 100 g of modified catalyst precursor E6 was added and allowed to stand at 120 °C for 50 minutes. The mass ratio of modified catalyst precursor, second aromatic hydrocarbon and second modifier was 1:3:0.3. The mixture was then washed repeatedly with a large amount of ethanol and dried at 140 °C for 7 hours to obtain catalyst F6.

[0096] The characterization results of catalyst F6 are as follows: the XRD pattern shows typical diffraction peaks characteristic of Beta zeolite; the static water contact angle is 134°; the mass content of Beta zeolite in the catalyst is 97.3%; the static water adsorption capacity is 181 mg / g; the SiO2 / Al2O3 molar ratio is 25; and the specific surface area of ​​the catalyst is 526 m². 2 / g, micropore volume is 0.19cm³ 3 / g. TEM images of catalyst F6 show that the Beta molecular sieve has a particulate morphology with a grain size of 28-45 nm.

[0097] Comparative Example 4

[0098] The only difference from Example 1 is that the pore-forming liquid treatment in preparation step e) was not performed. The specific preparation process of the catalyst is as follows:

[0099] 500 g of toluene and 10 g of N,O-bistrimethoxyalkylacetamide were mixed and stirred at 20 °C for 20 minutes. Then, 100 g of Beta molecular sieve (SiO2 / Al2O3 molar ratio of 25) was added and allowed to stand at 110 °C for 80 minutes. Finally, the mixture was dried at 140 °C for 6 hours to obtain modified molecular sieve powder A7. The mass ratio of molecular sieve powder, first aromatic hydrocarbon and first modifier was 1:5:0.1. Then, 18 g of modified molecular sieve powder A7, 60 g of silica powder (particle size 200 nm), 225 g of sodium silicate sol aqueous solution with a mass content of 40%, and 25.5 g of sodium aluminate (Al2O3 mass content 40%) were mixed evenly, wherein the molar ratio of modified molecular sieve powder, silica powder, silica sol, and aluminum source was 0.3:1:1.5:0.1. The mixture was then extruded and dried to obtain a strip-shaped catalyst preform B7 with a diameter of 1.5 mm, a length of 3-8 mm, and a clover-shaped cross-section. Then, 100 g of catalyst preform B7 was immersed in 120 g of tetraethylammonium hydroxide aqueous solution (mass concentration 10%) to obtain mixture C7. Mixture C7 was allowed to stand in a sealed space at 150°C for 50 hours, then washed with deionized water until the pH of the solution reached 7.5. It was then dried at 120°C for 8 hours, calcined at 560°C for 6 hours, and finally exchanged with a 7% ammonium sulfate solution at 55°C for 2 hours to obtain catalyst precursor D7. 300 g of ethylbenzene and 30 g of bis[(3-triethoxysilyl)propyl]amine were mixed and stirred at 60°C for 15 minutes, then 100 g of catalyst precursor D7 was added and allowed to stand at 120°C for 50 minutes. The mass ratio of catalyst precursor, second aromatic hydrocarbon, and second modifier was 1:3:0.3. The mixture was then repeatedly washed with a large amount of ethanol and dried at 140°C for 7 hours to obtain catalyst F7.

[0100] The characterization results of catalyst F7 are as follows: the XRD pattern shows typical diffraction peaks of Beta zeolite; the static water contact angle is 102°; the mass content of Beta zeolite in the catalyst is 98.5%; the static water adsorption capacity is 189 mg / g; the SiO2 / Al2O3 molar ratio is 25; and the specific surface area of ​​the catalyst is 483 m². 2 / g, micropore volume is 0.17cm³ 3 / g. TEM images of catalyst F7 show that the Beta molecular sieve has a particulate morphology with a grain size of 15-18 nm.

[0101]

Test Example 1

[0102] The catalysts F1-F7 prepared in Examples 1-3 and Comparative Examples 1-4 were tested for their single-pass lifetime in the alkylation of benzene and ethylene to ethylbenzene under reaction conditions with excessive water and alkaline impurities, respectively. The reaction conditions were 180°C, 3.6 MPa, and ethylene mass hourly space velocity (HHSV) of 1.0 h⁻¹. -1 The test was conducted under the following conditions: the molar ratio of benzene to ethylene was 2.0, the mass content of water impurities in the material was 1000 ppm, and the mass content of alkaline impurities was 3 ppm. The single-pass life refers to the time elapsed from the start of the reaction until the ethylene conversion rate drops to 40% of the initial conversion rate. The test results are shown in Table 1 below. The single-pass life of catalysts F1-F3 is significantly longer than that of catalysts F4-F7.

[0103] Table 1. Single-pass lifetime test results of catalysts under reaction conditions with excessive water and alkaline impurities.

[0104] Catalyst number Single-trip lifespan, h F1 560 F2 632 F3 507 F4 216 F5 135 F6 243 F7 167

[0105]

Test Example 2

[0106] Catalysts F1-F7 prepared in Examples 1-3 and Comparative Examples 1-4 were respectively applied to the alkylation reaction of benzene and ethylene to produce ethylbenzene, at a reaction temperature of 160°C, a pressure of 3.5 MPa, and an ethylene mass hourly space velocity of 2.6 h⁻¹. -1 Under the condition that the molar ratio of benzene to ethylene is 1.4, the ethylene conversion rate and the ethyl selectivity in the alkylation product were tested. The calculation formulas for the ethylene conversion rate (in moles) and the ethyl selectivity (in moles) are as follows, and the test results are shown in Table 2.

[0107] Ethylene conversion rate % = (Inlet ethylene content - Outlet ethylene content) / Inlet ethylene content × 100%.

[0108] Ethyl selectivity % = (molar amount of ethylbenzene + molar amount of diethylbenzene × 2 + molar amount of triethylbenzene × 3) / molar amount of ethylene consumed in the reaction × 100%.

[0109] Table 2. Test results of the alkylation reaction of benzene and ethylene to produce ethylbenzene.

[0110]

[0111]

[0112] As can be seen from Table 2, catalysts F1-F3 are significantly better than catalysts F4-F7 in terms of ethylene conversion and ethyl selectivity.

[0113] 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 Beta molecular sieve catalyst, characterized in that, The catalyst comprises a Beta molecular sieve with dual silicon groups, and the catalyst has a static water initial contact angle of 140-165° and a static water adsorption capacity of 130-170 mg / g.

2. The Beta molecular sieve catalyst according to claim 1, characterized in that, The catalyst is a binder-free molecular sieve catalyst, and / or Based on catalyst mass, the molecular sieve content is 95%-98%, and / or Based on the mass of the catalyst, the mass content of the disilicon groups, calculated as silicon oxide, is 2%-5%.

3. The Beta molecular sieve catalyst according to claim 1 or 2, characterized in that, The structural formula of the disilicon group is as follows: X1-X12 represent the positions connected to the Beta molecular sieve.

4. The Beta molecular sieve catalyst according to any one of claims 1-3, characterized in that, The Beta molecular sieve in the catalyst has a particulate morphology with a grain size of 5-20 nm, and / or The SiO2 / Al2O3 molar ratio of Beta molecular sieves is 16-50, and / or The catalyst has a specific surface area of ​​550-650 m². 2 / g; and / or The catalyst has a micropore volume of 0.18-0.21 cm³. 3 / g.

5. A method for preparing the Beta molecular sieve catalyst according to any one of claims 1-4, comprising the following steps: a) The molecular sieve raw powder, the first aromatic hydrocarbon and the first modifier are brought into contact and dried to obtain the modified molecular sieve raw powder; b) The modified molecular sieve powder, silicon source, aluminum source, and silica sol are mixed, shaped, and dried to obtain the catalyst preform; c) The catalyst preform and the template agent solution are brought into contact to obtain a mixture; d) Processing the mixture to obtain a catalyst precursor, wherein the processing may include closed heating, calcination and ammonium exchange; e) Contact the catalyst precursor and the pore-forming liquid, and process them to obtain a modified catalyst precursor, wherein the processing may include closed heating and calcination. f) The modified catalyst precursor, the second aromatic hydrocarbon, and the second modifier are contacted and treated to obtain the catalyst; wherein the treatment may include closed heating, washing, and drying. The first modifier is different from the second modifier.

6. The method according to claim 5, characterized in that, Step a) includes one or more of the following features: (1) The molecular sieve raw powder is Beta molecular sieve; (2) The SiO2 / Al2O3 molar ratio of the molecular sieve raw powder is 16-50; (3) The first aromatic hydrocarbon is selected from at least one of benzene, ethylbenzene and toluene; (4) The first modifier is a silazane, which is preferably selected from at least one of hexamethyldisilazane, hexamethyldisilaurea, N,O-bistrimethoxyalkylacetamide, and tetramethyldivinyldisilazane; (5) The mass ratio of the molecular sieve raw powder, the first aromatic hydrocarbon, and the first modifier is 1:(1.5-10):(0.05-0.2); (6) The contacting process includes mixing and stirring the first aromatic hydrocarbon and the first modifier at 10-40°C for 5-30 minutes, then adding the molecular sieve powder, and letting it stand or stirring at 90-130°C for 60-120 minutes.

7. The method according to claim 5 or 6, characterized in that, Step b) includes one or more of the following features: (1) The aluminum source is selected from at least one of aluminum chloride, aluminum nitrate, aluminum sulfate, aluminum isopropoxide, boehmite, aluminum hydroxide and sodium aluminate; (2) The silicon source is selected from silicon powder, and the particle size of the silicon powder is preferably 10nm-2000nm; (3) The silica sol is an alkaline silica sol. (4) The silica sol contains 35%-60% silica by mass; (5) The modified molecular sieve powder, silicon source and silica sol are all calculated as SiO2, and the aluminum source is calculated as Al2O3. The molar ratio of the modified molecular sieve powder, silicon source, silica sol and aluminum source is (0.1-0.5):1:(1.0-2.5):(0.04-0.22). Preferably, the molar ratio of the total SiO2 in the silicon source and silica sol to the Al2O3 in the aluminum source is 16-50:

1. And / or, step c) includes one or more of the following features: (1) The template agent solution is selected from at least one of tetraethylammonium hydroxide aqueous solution, tetraethylammonium bromide aqueous solution, trimethylcyclohexylammonium hydroxide aqueous solution and dimethylethylcyclohexylammonium hydroxide aqueous solution; (2) The mass concentration of the template agent solution is 6%-15%; (3) The mass ratio of the catalyst preform to the template agent solution is 1:(1-1.5); And / or, in step d), the closed heating treatment includes standing or stirring the mixture in a closed space at 140-170°C for 36-96 hours.

8. The method according to any one of claims 5-7, characterized in that, Step e) includes one or more of the following features: (1) The pore-forming solution is an aqueous solution of tetraethylammonium hydroxide or a mixed aqueous solution of tetraethylammonium hydroxide and tetraethylammonium bromide, and the mass concentration of the pore-forming solution is preferably 5%-15%; (2) The mass ratio of the catalyst precursor to the pore-forming liquid is 1:(1.5-2); (3) The closed heating treatment includes standing or stirring the catalyst precursor and the pore-forming liquid at 160-180℃ for 24-96 hours.

9. The method according to any one of claims 5-8, characterized in that, Step f) includes one or more of the following features: (1) The second aromatic hydrocarbon is selected from at least one of benzene, ethylbenzene and toluene; (2) The second modifier is a bissilane, and the preferred structural formula of the bissilane is... R1-R12 are each independently selected from C1-C6 alkoxy and C1-C6 alkoxy-C1-C6 alkyl, preferably each independently selected from methoxy, ethoxy or 3-methoxypropyl; preferably, the bissilane is selected from at least one of bis[(3-triethoxysilyl)propyl]amine, bis[(3-trimethoxysilyl)propyl]amine and 1,2-bis(triethoxysilyl)ethane; (3) The mass ratio of the modified catalyst precursor, the second aromatic hydrocarbon, and the second modifier is 1:(1.5-5.0):(0.1-0.5); (4) The closed heating treatment includes mixing and stirring the second aromatic hydrocarbon and the second modifier at 20-80°C for 10-30 minutes, then adding the modified second catalyst precursor, and letting it stand or stirring at 100-140°C for 30-60 minutes, followed by washing and drying.

10. A method for alkylating aromatic hydrocarbons with olefins, comprising contacting aromatic hydrocarbons and olefins in the presence of a Beta molecular sieve catalyst as described in any one of claims 1-4 or a Beta molecular sieve catalyst prepared according to any one of claims 5-9 to carry out an alkylation reaction to obtain alkyl aromatic hydrocarbons; Preferably, the aromatic hydrocarbon is selected from at least one of benzene and alkylbenzene, and more preferably from at least one of benzene, toluene, ethylbenzene, propylbenzene and butylbenzene; preferably, the olefin is selected from C2-C6 olefins, and more preferably from at least one of ethylene, propylene and butene; Preferably, the conditions for the alkylation reaction include: The reaction temperature is 120-250℃, the reaction pressure is 2.0-5.0 MPa, and the olefin mass hourly space velocity is 0.5-3.0 h⁻¹. -1 The molar ratio of aromatics to olefins is 1.0-3.

0.

11. Use of the Beta molecular sieve catalyst according to any one of claims 1-4 or the Beta molecular sieve catalyst prepared according to any one of claims 5-9 in the alkylation reaction of aromatics and olefins.

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