Preparation methods of MFI molecular sieves, MFI molecular sieves and their applications

Abstract

This invention relates to a method for preparing an MFI molecular sieve, comprising the following steps: (1) molding and drying a mixture of a first silicon source, a first aluminum source, and a second silicon source to obtain a precursor material containing amorphous silica and an aluminum source; (2) mixing the precursor material obtained in step (1) with a second aluminum source, a template agent, an alkali source, and water, and then crystallizing it to obtain an intermediate crystalline material; (3) calcining the intermediate crystalline material obtained in step (2), wherein the MFI molecular sieve contains no binder. Furthermore, this invention relates to an integral binder-free MFI molecular sieve for producing cyclopentylbenzene from benzene and cyclopentene, exhibiting good selectivity and few byproducts. This invention also relates to the use of this integral binder-free MFI molecular sieve as a catalyst in the production of cyclopentylbenzene and a method for catalytically producing cyclopentylbenzene using this integral binder-free MFI molecular sieve.

Description

Technical Field

[0001] This invention relates to MFI molecular sieves, specifically to an MFI molecular sieve, its preparation method, and its uses. Background Technology

[0002] With the rapid development of my country's ethylene industry, the production of C5 fractions, a byproduct of ethylene production, has increased accordingly. Cyclopentadiene is one of the more abundant components of C5 resources. Cyclopentene is an important basic organic chemical raw material, commonly used in the pharmaceutical industry, organic synthesis, and synthetic rubber. Cyclopentadiene can be hydrogenated to obtain cyclopentene. The most important derivatives of cyclopentene are cyclopentanone and cyclopentanol. Research on the production of cyclopentene from C5 fractions, and subsequently the synthesis of cyclopentanone and cyclopentanol, has attracted widespread attention.

[0003] Cyclopentylbenzene can be produced by the gas-phase alkylation reaction of cyclopentene and benzene, followed by oxidation and decomposition steps to obtain cyclopentanone and phenol. Similar to the production of phenol and acetone from cumene, the process route for producing phenol and cyclopentanone from cyclopentylbenzene also has the advantages of high cyclopentene conversion and good selectivity of target products.

[0004] Typically synthesized zeolite catalysts are fine powders with particle sizes ranging from a few nanometers to a few micrometers. These fine powders must be molded together with inorganic binders (clay, alumina, etc.) into different forms such as granules and strips to meet application requirements. The presence of binders disperses and dilutes the active components, blocks the pores of the zeolite molecular sieve, hinders the utilization of active sites, affects the diffusion of reactant molecules, and objectively reduces the selectivity of the reaction. Combining zeolite powders into binder-free monolithic catalysts is an interesting research hotspot. Monolithic catalysts refer to integrated catalysts with many narrow, neatly arranged pores. Compared with traditional molded granular catalysts, monolithic catalysts can improve catalytic efficiency and reaction selectivity, and also contribute to achieving low-energy consumption, low-emission, and safe processes. Currently, monolithic binder-free MFI molecular sieves are used in the gas-phase alkylation reaction for the preparation of cyclopentylbenzene. Summary of the Invention

[0005] In order to overcome the problems existing in the prior art, the present invention provides an integral binder-free MFI molecular sieve. When applied to the gas-phase alkylation reaction for the preparation of cyclopentylbenzene, the specific pore structure is suitable for the gas-phase alkylation reaction of benzene and cyclopentene, and has the characteristics of high activity, good selectivity and few by-products in this type of reaction.

[0006] On one hand, the present invention provides a method for preparing a monolithic binder-free MFI molecular sieve, comprising the following steps:

[0007] (1) The mixture of the first silicon source, the first aluminum source and the second silicon source is shaped and dried to obtain a precursor material containing amorphous silicon dioxide and aluminum source;

[0008] (2) The precursor material obtained in step (1) is mixed with the second aluminum source, template agent, alkali source and water, and then crystallized to obtain an intermediate crystalline material;

[0009] (3) The intermediate crystalline material obtained in step (2) is calcined;

[0010] The MFI molecular sieve contains no binder.

[0011] In some embodiments, the molar ratio of the first silicon source and the second silicon source, based on SiO2, is 1:(0.1 to 0.4), for example, 1:0.1, 1:0.15, 1:0.20, 1:0.25, 1:0.30, 1:0.35, or 1:0.38.

[0012] In some embodiments, the molar ratio of the first aluminum source to the second aluminum source, based on Al2O3, is 1:(0.1 to 1.2), for example, 1:0.15, 1:0.2, 1:0.25, 1:0.3, 1:0.35, 1:0.4, 1:0.5, 1:0.6, 1:0.7, 1:0.8, 1:0.9, 1:1, 1:1.1.

[0013] In some embodiments, the molar ratio of the first aluminum source to the second aluminum source, based on Al2O3, is 1:(0.1 to 0.4).

[0014] In some embodiments, the molar ratio of the first silicon source (SiO2) to the first aluminum source (Al2O3) is 1:(0.05 to 1.4), for example, 1:0.1, 1:0.15, 1:0.2, 1:0.25, 1:0.3, 1:0.35, 1:0.4, 1:0.45, 1:0.5, 1:0.55, 1:0.6, 1:0.7, 1:0.8, 1:0.9, 1:1, 1:1.1, 1:1.2, 1:1.3.

[0015] In some embodiments, the molar ratio of the first silicon source (SiO2) to the first aluminum source (Al2O3) is 1:(0.1 to 0.5).

[0016] In some embodiments, the molar ratio of the second silicon source (SiO2) to the second aluminum source (Al2O3) is 1:(0.05-0.6).

[0017] In some embodiments, the molar ratio of the second silicon source (SiO2) to the second aluminum source (Al2O3) is 1:(0.1 to 0.6), for example, 1:0.15, 1:0.2, 1:0.25, 1:0.3, 1:0.35, 1:0.4, 1:0.45, 1:0.5, or 1:0.55.

[0018] In some embodiments, the molar ratio of the second silicon source (SiO2) to the second aluminum source (Al2O3) is 1:(0.1 to 0.3).

[0019] In some embodiments, the molar ratio of the total silicon source (SiO2) to the second aluminum source (Al2O3) is 1:(0.01 to 0.08), for example, 1:0.01, 1:0.015, 1:0.02, 1:0.025, 1:0.03, 1:0.035, 1:0.04, 1:0.045, 1:0.05, 1:0.065, or 1:0.07.

[0020] In some embodiments, the molar ratio of the total silicon source (SiO2) to the second aluminum source (Al2O3) is 1:(0.02 to 0.067).

[0021] In some embodiments, the molar ratio of the total silicon source (SiO2) to the template agent is 1:(0.1-0.8), for example 1:0.2, 1:0.3, 1:0.4, 1:0.5, 1:0.6, 1:0.7.

[0022] In some embodiments, the molar ratio of the total silicon source (SiO2) to the alkali source is 1:(0.04-0.2), for example, 1:0.05, 1:0.08, 1:0.1, 1:0.13, 1:0.15, 1:0.17, or 1:0.20. In some embodiments, the molar ratio of the total silicon source (SiO2) to the alkali source is 1:(0.05-0.15).

[0023] In some embodiments, the total silicon source, calculated as SiO2, has a molar ratio of 1:(5-35) to water, for example, 1:7, 1:8, 1:9, 1:10, 1:11, 1:12, 1:13, 1:14, 1:15, 1:16, 1:17, 1:18, 1:19, 1:20, 1:21, 1:22, 1:23, 1:24, 1:23, 1:25, 1:27, 1:29, or 1:32.

[0024] In some embodiments, the total silicon source, calculated as SiO2, has a molar ratio of 1:(10-30) to water.

[0025] In some embodiments, the drying temperature is 80–200°C, for example, 100°C, 120°C, 130°C, 140°C, 150°C, 160°C, or 170°C. In some embodiments, the drying temperature is 100–150°C.

[0026] In some embodiments, the drying time is 2 to 24 hours, preferably 3 to 10 hours.

[0027] In some embodiments, the calcination temperature is 450–1000°C, for example 480°C, 500°C, 520°C, 550°C, 580°C, 600°C, 650°C, 700°C, 720°C, 750°C, or 800°C. In some embodiments, the calcination temperature is 500–750°C.

[0028] In some embodiments, the roasting time is 1 to 12 hours, for example, 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, 11 hours, or 12 hours. In some embodiments, the roasting time is 2 to 10 hours.

[0029] In some embodiments, the crystallization temperature is 140–220°C, for example, 140°C, 150°C, 160°C, 170°C, 180°C, 190°C, or 200°C. In some embodiments, the crystallization temperature is 150–200°C.

[0030] In some embodiments, the crystallization time is 12–110 hours, for example, 12 hours, 14 hours, 18 hours, 20 hours, 24 hours, 28 hours, 30 hours, 40 hours, 48 ​​hours, 50 hours, 56 hours, 60 hours, 64 hours, 70 hours, 72 hours, 76 hours, 80 hours, 85 hours, 90 hours, 95 hours, 100 hours, or 110 hours. In some embodiments, the crystallization time is 24–100 hours.

[0031] In some embodiments, the first silicon source includes one or more of solid silicon dioxide, silica gel, fumed silica, or silicon dioxide aerosol.

[0032] In some embodiments, the first aluminum source includes one or more of aluminum hydroxide, sodium aluminate, aluminum isopropoxide, aluminum nitrate, anhydrous aluminum trichloride, aluminum sulfate, kaolin, or montmorillonite.

[0033] In some embodiments, the second aluminum source includes one or more of aluminum hydroxide, sodium aluminate, aluminum isopropoxide, aluminum nitrate, anhydrous aluminum trichloride, or aluminum sulfate.

[0034] In some embodiments, the second silicon source is a silica sol. In some embodiments, the second silicon source is 10-50 wt% silica sol. In some embodiments, the second silicon source is 35-45 wt% silica sol.

[0035] In some embodiments, the template agent includes an organic amine template agent.

[0036] In some embodiments, the organic amine template agent includes one or more of tetrapropylammonium bromide, dimethylamine, trimethylamine, ethylenediamine, hexamethylenediamine, cyclohexylamine, isopropylamine, diethylamine, triethylamine, or n-butylamine.

[0037] In some embodiments, the organic amine template agent includes one or more of tetrapropylammonium bromide, isopropylamine, cyclohexylamine, hexamethylenediamine, ethylenediamine, diethylamine, n-butylamine, and triethylamine.

[0038] In some embodiments, the alkali source includes an alkali metal hydroxide; preferably, the alkali source is NaOH or KOH.

[0039] On the other hand, the present invention provides a monolithic binder-free MFI molecular sieve, wherein,

[0040] The molecular sieve has micropores and mesopores. The micropores are pores with a diameter of less than 2 nm, and the mesopores are pores with a diameter of 2 to 50 nm. The mesopores account for more than 56% of the total pore volume.

[0041] In some embodiments, the mesopores account for 56% to 86% of the total pore volume, for example, 56%, 60%, 62%, 65%, 68%, 70%, 72%, 75%, 78%, 80%, 83%, or 86%. In some embodiments, the mesopores account for 65% to 85% of the total pore volume. In some embodiments, the mesopores account for 70% to 80% of the total pore volume.

[0042] In some embodiments, the mesopores include a first mesopore, a second mesopore, and a third mesopore, wherein the pore diameter d1 of the first mesopore satisfies: 2.0 nm < d1 ≤ 5.0 nm, the pore diameter d2 of the second mesopore satisfies: 5.0 nm < d2 ≤ 20 nm, and the pore diameter d3 of the third mesopore satisfies: 20 nm < d3 < 50 nm.

[0043] In some embodiments, the pore volume of the first mesopore accounts for 30% to 50% of the total pore volume, preferably 30% to 45%, for example 32%, 35%, 38%, 40%, 42% or 45%.

[0044] In some embodiments, the pore volume of the second mesopore accounts for 20% to 33% of the total pore volume, preferably 20% to 30%, for example 22%, 25%, 28% or 30%.

[0045] In some embodiments, the pore volume of the third mesopore accounts for less than 12% of the total pore volume, for example, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, or 11%. In some embodiments, the pore volume of the third mesopore accounts for 5% to 11% of the total pore volume. In some embodiments, the pore volume of the third mesopore accounts for 6% to 11% of the total pore volume.

[0046] In some embodiments, the acidity of the molecular sieve is 0.9 to 2 mmol / g, for example 0.95 mmol / g, 0.98 mmol / g, 1.00 mmol / g, 1.05 mmol / g, 1.10 mmol / g, 1.15 mmol / g, 1.25 mmol / g, 1.35 mmol / g, 1.45 mmol / g or 1.5 mmol / g.

[0047] In some embodiments, the specific surface area of ​​the molecular sieve is 400–600 m². 2 / g, for example 400m 2 / g、420m 2 / g、450m 2 / g、480m 2 / g、500m 2 / g、520m 2 / g、540m 2 / g、550m 2 / g、560m 2 / g or 580m 2 / g.

[0048] In some embodiments, the average pore size of the molecular sieve is 2.5 nm to 5.5 nm. In some embodiments, the average pore size of the molecular sieve is 3 to 4.7 nm. In some embodiments, the average pore size of the molecular sieve is 3.2 to 4.5 nm.

[0049] In some embodiments, the total pore volume of the molecular sieve is 0.3–0.8 cm³. 3 / g, for example 0.35cm 3 / g, 0.4cm 3 / g, 0.45cm 3 / g, 0.5cm 3 / g, 0.55cm 3 / g, 0.6cm 3 / g, 0.65cm 3 / g, 0.7cm 3 / g, 0.75cm 3 / g. In some embodiments, the total pore volume of the molecular sieve is 0.4–0.7 cm³. 3 / g.

[0050] In some embodiments, the micropore volume of the molecular sieve is 0.1–0.5 cm³. 3 / g, for example, 0.1cm 3 / g, 0.2cm 3 / g, 0.22cm 3 / g, 0.25cm 3 / g, 0.3cm 3 / g, 0.35cm 3 / g, 0.38cm 3 / g, 0.4cm 3 / g or 0.45cm 3 / g.

[0051] In some embodiments, the molecular sieve has one or more of the following features (a) to (h):

[0052] (a) The acidity of the molecular sieve is 0.9 to 2 mmol / g, preferably 1 to 1.5 mmol / g;

[0053] (b) The specific surface area of ​​the molecular sieve is 400–600 m². 2 / g;

[0054] (c) The average pore size of the molecular sieve is 2.5 nm to 5.5 nm, preferably 3 nm to 4.7 nm; more preferably 3.2 nm to 4.5 nm;

[0055] (d) The total pore volume of the molecular sieve is 0.3–0.8 cm³. 3 / g, preferably 0.35~0.75cm 3 / g; preferably 0.4~0.7cm 3 / g;

[0056] (e) The micropore volume of the molecular sieve is 0.1–0.5 cm³. 3 / g, preferably 0.22~0.45cm 3 / g;

[0057] (f) The pore volume of the first mesopore accounts for 30% to 50% of the total pore volume, preferably 30% to 45%; the pore volume of the second mesopore accounts for 20% to 33% of the total pore volume, preferably 20% to 30%; and the pore volume of the third mesopore accounts for less than 12% of the total pore volume, preferably 6% to 11%.

[0058] (g) The molecular sieve exhibits a closed hysteresis loop on the nitrogen adsorption-desorption curve at P / P0 = 0.4-0.99, preferably with the starting position of the closed hysteresis loop at P / P0 = 0.4-0.7; the mass difference between the adsorption and desorption curves is 0-6 cm⁻¹. 2 / g;

[0059] (h) The molecular sieve X-ray diffraction (XRD) pattern has characteristic peaks at 2θ angles of 8.0°±0.25° and 9.0±0.4°, preferably at 8.0°±0.20° and 9.0±0.35°.

[0060] On the other hand, the present invention provides the use of monolithic binder-free MFI molecular sieves or monolithic binder-free MFI molecular sieves prepared by the preparation method described in the present invention as catalysts in the production of cyclopentylbenzene.

[0061] Preferably, the raw materials for producing cyclopentylbenzene contain benzene and cyclopentene.

[0062] On the other hand, the present invention provides a method for producing cyclopentylbenzene, wherein benzene and cyclopentene are used as raw materials, and the raw materials are reacted with a catalyst to synthesize cyclopentylbenzene. The catalyst is the monolithic binder-free MFI molecular sieve of the present invention or the monolithic binder-free MFI molecular sieve prepared by the preparation method of the present invention.

[0063] In some embodiments, the molar ratio of benzene to cyclopentene is (1-5):1; preferably, the molar ratio of benzene to cyclopentene is (1-3):1.

[0064] In some embodiments, the reaction temperature is 150–300°C, the reaction pressure is 0.8–1.5 MPa, and the weight hourly space velocity (WHSV) of cyclopentene is 0.05–2 h⁻¹. -1 Preferably, the reaction temperature is 150–250°C, the reaction pressure is 0.9–1.2 MPa (e.g., 1 MPa), and the weight hourly space velocity (WHSV) of cyclopentene is 0.05–1 h⁻¹. -1 .

[0065] The monolithic binder-free MFI molecular sieve catalyst provided by this invention has a large specific surface area and high acidity. When benzene and cyclopentene are used as raw materials to produce cyclopentylbenzene, the specific pore structure is suitable for the gas-phase alkylation reaction of benzene and cyclopentene. In this type of reaction, it has the characteristics of high activity, good selectivity and few by-products.

[0066] The preparation method of the monolithic binder-free MFI molecular sieve described in this invention involves a special process. First, a silicon source and a first aluminum source are extruded and dried using silica sol. Then, a second aluminum source, an alkali source, a template agent, and water are used for liquid-phase hydrothermal crystallization, followed by calcination. This method utilizes the weak guiding ability of small-molecule organic amine template agents during the crystallization process, allowing the precursor containing amorphous silica and aluminum source materials to be transformed in situ into a monolithic binder-free MFI molecular sieve. Due to the interfacial shrinkage effect during crystallization, numerous regularly arranged mesopores are generated. The monolithic binder-free MFI molecular sieve of this invention possesses both a regular mesoporous structure and the unique channel structure and morphological characteristics of MFI molecular sieves. These specific structural features enable this molecular sieve to exhibit good catalytic activity, faster material diffusion rate, and more stable catalyst performance when applied to the catalytic gas-phase alkylation of benzene and cyclopentene. Attached Figure Description

[0067] The accompanying drawings are provided to further understand this application and form part of the specification. They are used together with the following detailed description to explain this application, but do not constitute a limitation thereof.

[0068] Figure 1 The XRD pattern of the monolithic binder-free MFI molecular sieve prepared in Example 1 of this invention.

[0069] Figure 2 The N2 adsorption-desorption curves are for the monolithic binder-free MFI molecular sieve prepared in Example 1 of this invention. Detailed Implementation

[0070] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments and accompanying drawings. The specific embodiments described herein are for illustrative purposes only and are not intended to limit the invention in any way. Furthermore, descriptions of well-known structures and technologies are omitted in the following description to avoid unnecessary confusion.

[0071] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0072] In this article, "n~m units" and "n units~m units" have the same meaning, where n and m are numerical values ​​and the unit is the unit of that numerical value. For example, 450~1000℃ and 450℃~1000℃ have the same meaning, indicating the range from 450℃ to 1000℃.

[0073] The extrusion aid can be one or more of the following: guar gum powder, methylcellulose, ethylcellulose, graphite, starch, polyvinyl alcohol, and polyacrylamide. In some embodiments of the present invention, guar gum powder is used as the extrusion aid.

[0074] The present invention uses the following equipment to characterize the prepared monolithic binder-free MFI molecular sieve. The following examples all use the same characterization equipment and testing methods.

[0075] In this invention, a Rigaku-Ultima X-ray diffractometer from Japan was used for molecular sieve crystal phase analysis. The XRD test conditions were: CuKα radiation, wavelength λ = 0.15432 nm; X-ray diffraction pattern scanning range 2θ = 5° to 50°, scanning speed 10° / min, working voltage 40 kV, and current 40 mA.

[0076] In this invention, the average pore size and total pore volume of the molecular sieve are determined by N2 physical adsorption. The test method is as follows: The specific surface area (BET) and pore volume of the sample are analyzed using an Autosorb-I type automatic adsorption specific surface area and porosity analyzer from Quantachrome, USA, wherein the cold trap is liquid nitrogen and the adsorption medium is high-purity nitrogen gas; the low-pressure section of the adsorption isotherm is analyzed using the adsorption isotherm equation of the HK model to obtain the pore size distribution curve of the molecular sieve; the specific surface area and pore volume of the molecular sieve are calculated by the BET method and the t-plot method, respectively.

[0077] In this invention, gas chromatography is used to analyze the products. A certain amount of the reaction mixture is injected into the gas chromatograph through the injection port, flows through the chromatographic column, is detected by FID, and is quantitatively analyzed by the external standard method. The gas chromatograph used is an Agilent 7890 gas chromatograph, and the analytical column used is an INNOWAX column.

[0078] The formulas for calculating conversion rate and selectivity in the application examples of this invention are as follows:

[0079] Cyclopentene conversion rate X HPE = Percentage of chromatographic products and byproducts by mass / (Percentage of chromatographic products and byproducts by mass + Percentage of cyclopentene by mass) × 100%.

[0080] Selectivity of cyclopentylbenzene HPB = Percentage of cyclopentylbenzene by mass / (Percentage of each product and byproduct by mass in chromatography) × 100%.

[0081] The method for determining the acid content of molecular sieves in the application examples of this invention is as follows:

[0082] Weigh 0.5 g of molecular sieve powder, add 100 mL of water, stir for 10 minutes, add 0.2 g of piperidine, stir for 30 minutes, add 2 drops of phenolphthalein, and then titrate with a 0.2 mol / L potassium hydrogen phthalate aqueous solution until the phenolphthalein changes color. Calculate the volume of potassium hydrogen phthalate aqueous solution used in the titration, and calculate the acid content of the molecular sieve, in millimoles per gram (mmol / g). The calculation formula is as follows:

[0083] Molecular sieve acid content = (weight of piperidine / 85.15 - concentration of potassium hydrogen phthalate × volume of potassium hydrogen phthalate / 1000) / weight of molecular sieve × 1000.

[0084] The following embodiments and accompanying drawings are provided to aid in understanding the present invention. However, it should be understood that these embodiments and drawings are for illustrative purposes only and do not constitute any limitation. The actual scope of protection of the present invention is set forth in the claims. It should be understood that any modifications and changes can be made without departing from the spirit of the present invention.

[0085] Example

[0086] Examples 1-10 were prepared using the following method:

[0087] 1) Mix the first silicon source and the first aluminum source, and add an appropriate amount of extrusion aid guar gum powder to the second silicon source to form a strip with a diameter of 1 mm and a length of 0.5 cm. Dry the formed strip at a certain temperature for a certain time to obtain the precursor silicon material.

[0088] 2) A certain mass of the second aluminum source, template agent, alkali source, and H2O are dissolved and mixed; the precursor silicon material is added to the mixture. The mixture is crystallized at a certain temperature for a certain time to obtain an intermediate crystalline material. This intermediate crystalline material is removed from the liquid, washed with deionized water, dried, and calcined in a muffle furnace at a certain temperature for a certain time to obtain a monolithic binder-free MFI molecular sieve.

[0089] The reaction conditions for each embodiment are shown in Table 1, and the reactants and their amounts are shown in Table 2.

[0090] Table 1: Reaction Conditions

[0091] Example Drying temperature Drying time Crystallization temperature Crystallization time Calcination temperature roasting time 1 120℃ 3 hours 180℃ 48 hours 550℃ 5 hours 2 100℃ 10 hours 150℃ 72 hours 500℃ 10 hours 3 130℃ 5 hours 160℃ 100 hours 750℃ 2 hours 4 150℃ 3 hours 200℃ 24 hours 650℃ 8 hours 5 140℃ 4 hours 175℃ 48 hours 700℃ 3 hours 6 110℃ 8 hours 160℃ 72 hours 600℃ 4 hours 7 120℃ 5 hours 170℃ 36 hours 680℃ 4.5 hours 8 135℃ 7 hours 165℃ 70 hours 720℃ 3 hours 9 125℃ 9 hours 190℃ 36 hours 700℃ 6 hours 10 130℃ 6 hours 160℃ 55 hours 580℃ 9 hours

[0092] Table 2: Reactants

[0093]

[0094]

[0095] Table 2 (continued)

[0096]

[0097]

[0098] Parameter test results for Examples 1-10:

[0099] Example 1: XRD characterization results of molecular sieves are as follows Figure 1 As shown, the N2 physical adsorption characterization results are as follows: Figure 2 As shown. From Figure 1 It can be seen that this molecular sieve is a typical MFI molecular sieve. From Figure 2 Hysteresis loops were observed, confirming the presence of mesopores. The measured pore volume was as follows: pores smaller than 2.0 nm accounted for 25% of the total pore volume; pores with diameters between 2.0 and 5.0 nm accounted for 38%; pores with diameters between 5.0 and 20.0 nm accounted for 29%; and pores larger than 20.0 nm to 50.0 nm accounted for 8%. The average channel diameter was 3.9 nm, and the total pore volume was 0.55 cm³. 3 / g, micropore volume is 0.31cm³ 3 / g, specific surface area is 520m² 2 / g. The acidity of the molecular sieve is 1.28 mmol / g.

[0100] Example 2: The N2 physical adsorption characterization results of the molecular sieve showed a hysteresis loop, confirming the presence of mesopores. The measured pore volume was as follows: pores smaller than 2.0 nm accounted for 20% of the total pore volume; pores with a diameter of 2.0–5.0 nm accounted for 45%; pores with a diameter of 5.0–20.0 nm accounted for 29%; and pores with a diameter greater than 20.0 nm to 50.0 nm accounted for 6%. The average pore diameter was 3.6 nm, and the total pore volume was 0.46 cm³. 3 / g, micropore volume is 0.26cm³ 3 / g, specific surface area is 402m² 2 / g. The acidity of the molecular sieve is 1.17 mmol / g.

[0101] Example 3: The N2 physisorption characterization results of the molecular sieve showed a hysteresis loop, confirming the presence of mesopores. The measured pore volume was as follows: pores smaller than 2.0 nm accounted for 29% of the total pore volume; pores with a diameter of 2.0–5.0 nm accounted for 44%; pores with a diameter of 5.0–20.0 nm accounted for 20%; and pores with a diameter greater than 20.0 nm to 50.0 nm accounted for 7%. The average pore diameter was 3.7 nm, and the total pore volume was 0.40 cm³. 3 / g, micropore volume is 0.22cm³3 / g, specific surface area is 423m² 2 / g. The acidity of the molecular sieve is 1.41 mmol / g.

[0102] Example 4: The N2 physical adsorption characterization results of the molecular sieve showed a hysteresis loop, confirming the presence of mesopores. The measured pore volume was as follows: pores smaller than 2.0 nm accounted for 23% of the total pore volume; pores with a diameter of 2.0–5.0 nm accounted for 40%; pores with a diameter of 5.0–20.0 nm accounted for 28%; and pores with a diameter greater than 20.0 nm to 50.0 nm accounted for 7%. The average pore diameter was 4.3 nm, and the total pore volume was 0.51 cm³. 3 / g, micropore volume is 0.38cm³ 3 / g, specific surface area is 543m² 2 / g. The acidity of the molecular sieve is 1.38 mmol / g.

[0103] Example 5: The N2 physisorption characterization results of the molecular sieve showed a hysteresis loop, confirming the presence of mesopores. The measured pore volume was as follows: pores smaller than 2.0 nm accounted for 15% of the total pore volume; pores with a diameter of 2.0–5.0 nm accounted for 45%; pores with a diameter of 5.0–20.0 nm accounted for 30%; and pores with a diameter greater than 20.0 nm to 50.0 nm accounted for 10%. The average pore diameter was 4.0 nm, and the total pore volume was 0.63 cm³. 3 / g, micropore volume is 0.42cm³ 3 / g, specific surface area is 468m² 2 / g. The acidity of the molecular sieve is 1.50 mmol / g.

[0104] Example 6: The N2 physisorption characterization results of the molecular sieve showed a hysteresis loop, confirming the presence of mesopores. The measured pore volume was as follows: pores smaller than 2.0 nm accounted for 30% of the total pore volume; pores with a diameter of 2.0–5.0 nm accounted for 43%; pores with a diameter of 5.0–20.0 nm accounted for 20%; and pores with a diameter greater than 20.0 nm to 50.0 nm accounted for 9%. The average pore diameter was 4.5 nm, and the total pore volume was 0.55 cm³. 3 / g, micropore volume is 0.37cm³ 3 / g, specific surface area is 487m² 2 / g. The acidity of the molecular sieve is 1.22 mmol / g.

[0105] Example 7: The N2 physisorption characterization results of the molecular sieve showed a hysteresis loop, confirming the presence of mesopores. The measured pore volume was as follows: pores smaller than 2.0 nm accounted for 28% of the total pore volume; pores with a diameter of 2.0–5.0 nm accounted for 32%; pores with a diameter of 5.0–20.0 nm accounted for 29%; and pores with a diameter greater than 20.0 nm to 50.0 nm accounted for 11%. The average pore diameter was 4.1 nm, and the total pore volume was 0.70 cm³. 3 / g, micropore volume is 0.45cm³ 3 / g, specific surface area is 570m² 2 / g. The acidity of the molecular sieve is 1.02 mmol / g.

[0106] Example 8: The N2 physisorption characterization results of the molecular sieve showed a hysteresis loop, confirming the presence of mesopores. The measured pore volume was as follows: pores smaller than 2.0 nm accounted for 30% of the total pore volume; pores with a diameter of 2.0–5.0 nm accounted for 30%; pores with a diameter of 5.0–20.0 nm accounted for 29%; and pores with a diameter greater than 20.0 nm to 50.0 nm accounted for 11%. The average channel diameter was 3.3 nm, and the total pore volume was 0.67 cm³. 3 / g, micropore volume is 0.43cm³ 3 / g, specific surface area is 600m² 2 / g. The acidity of the molecular sieve is 1.14 mmol / g.

[0107] Example 9: The N2 physisorption characterization results of the molecular sieve showed a hysteresis loop, confirming the presence of mesopores. The measured pore volume was as follows: pores smaller than 2.0 nm accounted for 28% of the total pore volume; pores with a diameter of 2.0–5.0 nm accounted for 34%; pores with a diameter of 5.0–20.0 nm accounted for 30%; and pores with a diameter greater than 20.0 nm to 50.0 nm accounted for 8%. The average pore diameter was 3.2 nm, and the total pore volume was 0.49 cm³. 3 / g, micropore volume is 0.29cm³ 3 / g, specific surface area 540m² 2 / g. The acidity of the molecular sieve is 1.29 mmol / g.

[0108] Example 10: The N2 physisorption characterization results of the molecular sieve showed a hysteresis loop, confirming the presence of mesopores. The measured pore volume was as follows: pores smaller than 2.0 nm accounted for 24% of the total pore volume; pores with a diameter of 2.0–5.0 nm accounted for 43%; pores with a diameter of 5.0–20.0 nm accounted for 25%; and pores with a diameter greater than 20.0 nm to 50.0 nm accounted for 8%. The average pore diameter was 3.8 nm, and the total pore volume was 0.59 cm³. 3 / g, micropore volume is 0.34cm³ 3 / g, specific surface area is 571m² 2 / g. The acidity of the molecular sieve is 1.35 mmol / g.

[0109] Application methods

[0110] Five g of the prepared monolithic binder-free MFI molecular sieve was packed into a fixed-bed reactor, and a mixture of benzene and cyclopentene was introduced. The reaction was carried out at a temperature of 180 °C, a pressure of 1.0 MPa, and a space velocity of 0.05 h⁻¹ for cyclopentene. -1 The molar ratio of benzene to cyclopentene was 1.5:1. The reaction results of Examples 1-10 are shown in Table 3.

[0111] Table 3: Reaction Results of Examples

[0112] Example Conversion rate of cyclopentene Selectivity of cyclopentylbenzene 1 95.5％ 92.3％ 2 98％ 94.7％ 3 100％ 91.4％ 4 99.2％ 92.6％ 5 97％ 94.5％ 6 94.3％ 95.6％ 7 98.7％ 91.5％ 8 90.8％ 90.3％ 9 92.9％ 93.7％ 10 96.4％ 90.6％

[0113] Examples 1A to 1E

[0114] Except for the molar ratios of total silicon source (SiO2) and second aluminum source (Al2O3), the molar ratio of alkali source, and the molar ratio of water, which differ from Example 1 (see Table 4), the same reaction conditions and reactants as in Example 1 were used.

[0115] Catalyst parameter test results:

[0116] Example 1A: No hysteresis loop was observed. The measured pore volume was as follows: pores with a diameter less than 2.0 nm accounted for 33% of the total pore volume; pores with a diameter between 2.0 and 5.0 nm accounted for 49%; pores with a diameter between 5.0 and 20.0 nm accounted for 15%; and pores with a diameter greater than 20.0 nm to 50.0 nm accounted for 3%. The average channel diameter was 2.3 nm, and the total pore volume was 0.32 cm³. 3 / g, micropore volume is 0.21cm³ 3 / g, specific surface area is 402m² 2 / g. The acidity of the molecular sieve is 0.93 mmol / g.

[0117] Example 1B: No hysteresis loop was observed. The measured pore volume was as follows: pores smaller than 2.0 nm accounted for 35% of the total pore volume; pores with diameters between 2.0 and 5.0 nm accounted for 46%; pores with diameters between 5.0 and 20.0 nm accounted for 14%; and pores with diameters greater than 20.0 nm to 50.0 nm accounted for 5%. The average channel diameter was 2.1 nm, and the total pore volume was 0.25 cm³. 3 / g, micropore volume is 0.13cm³ 3 / g, specific surface area is 375m² 2 / g. The acidity of the molecular sieve is 0.87 mmol / g.

[0118] Example 1C: No hysteresis loop was observed. The measured pore volume was as follows: pores with a diameter less than 2.0 nm accounted for 31% of the total pore volume; pores with a diameter of 2.0–5.0 nm accounted for 47%; pores with a diameter of 5.0–20.0 nm accounted for 17%; and pores with a diameter greater than 20.0 nm to 50.0 nm accounted for 5%. The average channel diameter was 2.8 nm, and the total pore volume was 0.25 cm³. 3 / g, micropore volume is 0.12cm³ 3 / g, specific surface area is 386m² 2 / g. The acidity of the molecular sieve is 0.98 mmol / g.

[0119] Example 1D: No hysteresis loop was observed. The measured pore volume was as follows: pores smaller than 2.0 nm accounted for 35% of the total pore volume; pores with diameters between 2.0 and 5.0 nm accounted for 46%; pores with diameters between 5.0 and 20.0 nm accounted for 14%; and pores with diameters greater than 20.0 nm to 50.0 nm accounted for 5%. The average channel diameter was 2.3 nm, and the total pore volume was 0.25 cm³. 3 / g, micropore volume is 0.14cm³ 3 / g, specific surface area is 364m² 2 / g. The acidity of the molecular sieve is 0.94 mmol / g.

[0120] Example 1E: No hysteresis loop was observed. The measured pore volume was as follows: pores smaller than 2.0 nm accounted for 25% of the total pore volume; pores with diameters between 2.0 and 5.0 nm accounted for 48%; pores with diameters between 5.0 and 20.0 nm accounted for 22%; and pores larger than 20.0 nm to 50.0 nm accounted for 5%. The average channel diameter was 2.4 nm, and the total pore volume was 0.26 cm³. 3 / g, micropore volume is 0.11cm³ 3 / g, specific surface area is 367m² 2 / g. The acidity of the molecular sieve is 0.87 mmol / g.

[0121] Reaction results: The same application method as in Example 1 was used. The reaction results are shown in Table 4:

[0122] Table 4: Reaction Results

[0123]

[0124] Comparative Example 1

[0125] 40% silica sol (28.94 g) was dissolved and mixed with certain amounts of aluminum sulfate, triethylamine, NaOH, and H₂O. The molar ratio of SiO₂, Al₂O₃, triethylamine, NaOH, and water in this mixture was 1:0.025:0.50:0.10:25. The mixture was crystallized at 180°C for 48 hours to obtain molecular sieve raw powder. The raw powder was filtered, washed with deionized water, and dried. The obtained powder was mixed with boehmite and 5% dilute nitric acid, with an appropriate amount of extrusion aid, and shaped into strips with a diameter of 1 mm and a length of 0.5 cm. The mass ratio of raw powder to alumina was 6.5:3.5. The shaped strips were dried at 120°C for 3 hours. The dried strips were calcined in a muffle furnace at 550°C for 5 hours to obtain MFI molecular sieve synthesized using conventional methods and shaped using a binder.

[0126] Parameter test results:

[0127] Similarly, using the testing method described in the above embodiments, no hysteresis loop was observed, the molecular sieve had an average pore diameter of 2.3 nanometers, and a total pore volume of 0.24 cm³. 3 g -1 The micropore volume is 0.16 cm³. 3 g -1 The measured pore volume was as follows: pores with a diameter less than 2.0 nm accounted for 32% of the total pore volume; pores with a diameter of 2.0–5.0 nm accounted for 47%; pores with a diameter of 5.0–20.0 nm accounted for 18%; and pores with a diameter greater than 20.0 nm to 50.0 nm accounted for less than 3%. The specific surface area of ​​the MFI molecular sieve was measured to be 279 cm². 2 / g. The acidity of the molecular sieve is 1.10 mmol / g.

[0128] Reaction results:

[0129] The same application method as in Example 1 was used. The conversion rate of cyclopentene was 88.1%, and the selectivity of cyclopentylbenzene was 79.6%.

[0130] The preferred 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 combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for preparing MFI molecular sieves, comprising the following steps: (1) The mixture of the first silicon source, the first aluminum source and the second silicon source is shaped and dried to obtain a precursor material containing amorphous silicon dioxide and aluminum source; (2) The precursor material obtained in step (1) is mixed with the second aluminum source, template agent, alkali source and water, and then crystallized to obtain an intermediate crystalline material; (3) The intermediate crystalline material obtained in step (2) is calcined. The MFI molecular sieve contains no binder; Based on SiO2, the molar ratio of the first silicon source to the second silicon source is 1:(0.1~0.4). Based on Al2O3, the molar ratio of the first aluminum source to the second aluminum source is 1:(0.1~1.2). The molar ratio of the first silicon source (calculated as SiO2) to the first aluminum source (calculated as Al2O3) is 1:(0.05~1.4). The molar ratio of the second silicon source (SiO2) to the second aluminum source (Al2O3) is 1:(0.1~0.6). The molar ratio of the total silicon source (SiO2) to the second aluminum source (Al2O3) is 1:(0.02-0.067). The total silicon source, calculated as SiO2, has a molar ratio of 1:(0.1-0.8) to the template agent. The molar ratio of the total silicon source (SiO2) to the alkali source is 1:(0.05-0.15). The total silicon source, calculated as SiO2, has a molar ratio of 1:(10-30) to water. The crystallization temperature is 140~220℃; The crystallization time is 12-110 hours; The second silicon source is silica sol; The template agent includes one or more of tetrapropylammonium bromide, dimethylamine, trimethylamine, ethylenediamine, hexamethylenediamine, cyclohexylamine, isopropylamine, diethylamine, triethylamine, or n-butylamine.

2. The preparation method according to claim 1, characterized in that, Based on Al2O3, the molar ratio of the first aluminum source to the second aluminum source is 1:(0.1–0.4); and / or, The molar ratio of the first silicon source (SiO2) to the first aluminum source (Al2O3) is 1:(0.1–0.5); and / or, The molar ratio of the second silicon source (SiO2) to the second aluminum source (Al2O3) is 1:(0.1~0.3).

3. The preparation method according to claim 1, characterized in that, The drying temperature is 80~200℃; the drying time is 2~24 h; and / or The calcination temperature is 450~1000 ℃; and / or The calcination time is 1-12 h; and / or The crystallization temperature is 150~200℃; and / or The crystallization time is 24~100 h.

4. The preparation method according to claim 3, characterized in that, The drying temperature is 100~150℃.

5. The preparation method according to claim 3, characterized in that, The drying time is 3 to 10 hours.

6. The preparation method according to claim 3, characterized in that, The roasting temperature is 500~750 ℃.

7. The preparation method according to claim 3, characterized in that, The roasting time is 2 to 10 hours.

8. The preparation method according to any one of claims 1-7, characterized in that, The first silicon source includes one or more of solid silica, silica gel, fumed silica, or silica aerosol; and / or The first aluminum source includes one or more of aluminum hydroxide, sodium aluminate, aluminum isopropoxide, aluminum nitrate, anhydrous aluminum trichloride, aluminum sulfate, kaolin, or montmorillonite; and / or The second aluminum source includes one or more of aluminum hydroxide, sodium aluminate, aluminum isopropoxide, aluminum nitrate, anhydrous aluminum trichloride, or aluminum sulfate; and / or The second silicon source is 10-50 wt% silica sol; and / or The template agent includes one or more of tetrapropylammonium bromide, isopropylamine, cyclohexylamine, hexamethylenediamine, ethylenediamine, diethylamine, n-butylamine, or triethylamine; and / or The alkali source includes alkali metal hydroxides.

9. The preparation method according to claim 8, characterized in that, The alkali source is NaOH or KOH.

10. A monolithic binder-free MFI molecular sieve, wherein, The MFI molecular sieve is obtained by the preparation method according to any one of claims 1-9; The molecular sieve has micropores and mesopores. The micropores are pores with a diameter of less than 2 nm, and the mesopores are pores with a diameter of 2 to 50 nm. The mesopores account for more than 56% of the total pore volume. The mesopores include a first mesopore, a second mesopore, and a third mesopore. The pore diameter d1 of the first mesopore satisfies: 2.0 nm < d1 ≤ 5.0 nm, the pore diameter d2 of the second mesopore satisfies: 5.0 nm < d2 ≤ 20 nm, and the pore diameter d3 of the third mesopore satisfies: 20 nm < d3 < 50 nm. Wherein, the pore volume of the first mesopore accounts for 30% to 50% of the total pore volume, the pore volume of the second mesopore accounts for 20% to 33% of the total pore volume, and the pore volume of the third mesopore accounts for less than 12% of the total pore volume; The molecular sieve exhibits a closed hysteresis loop at P / P0 = 0.4-0.99 on the nitrogen adsorption-desorption curve; the mass difference between the adsorption and desorption curves is 0-6 cm. 2 / g.

11. The MFI molecular sieve according to claim 10, characterized in that, The molecular sieve has one or more of the following characteristics (a) to (h): (a) The acidity of the molecular sieve is 0.9~2 mmol / g; (b) The specific surface area of ​​the molecular sieve is 400~600 m². 2 / g; (c) The average pore size of the molecular sieve is 2.5~5.5 nm; (d) The total pore volume of the molecular sieve is 0.3~0.8 cm³. 3 / g; (e) The micropore volume of the molecular sieve is 0.1~0.5 cm³. 3 / g; (f) The pore volume of the first mesopore accounts for 30%-45% of the total pore volume, the pore volume of the second mesopore accounts for 20%-30% of the total pore volume, and the pore volume of the third mesopore accounts for 6-11% of the total pore volume; (g) The molecular sieve exhibits a closed hysteresis loop at P / P0 = 0.45-0.99 on the nitrogen adsorption-desorption curve; (h) The X-ray diffraction (XRD) pattern of the molecular sieve has characteristic peaks at 2θ angles of 8.0º±0.25º and 9.0±0.4º.

12. The MFI molecular sieve according to claim 11, characterized in that, The molecular sieve has an acid content of 1~1.5 mmol / g.

13. The MFI molecular sieve according to claim 11, characterized in that, The molecular sieve has an average pore size of 3~4.7 nm.

14. The MFI molecular sieve according to claim 13, characterized in that, The molecular sieve has an average pore size of 3.2~4.5 nm.

15. The MFI molecular sieve according to claim 11, characterized in that, The total pore volume of the molecular sieve is 0.35~0.75 cm³. 3 / g.

16. The MFI molecular sieve according to claim 11, characterized in that, The total pore volume of the molecular sieve is 0.4~0.7 cm³. 3 / g.

17. The MFI molecular sieve according to claim 11, characterized in that, The molecular sieve has a micropore volume of 0.22~0.45 cm³. 3 / g.

18. The MFI molecular sieve according to claim 11, characterized in that, The X-ray diffraction (XRD) pattern of the molecular sieve has characteristic peaks at 2θ angles of 8.0º±0.20º and 9.0±0.35º.

19. The use of the monolithic binderless MFI molecular sieve prepared by any one of claims 1-9 or the monolithic binderless MFI molecular sieve according to any one of claims 10-18 as a catalyst in the production of cyclopentylbenzene.

20. The use according to claim 19, characterized in that, The raw materials used to produce cyclopentylbenzene contain benzene and cyclopentene.

21. A method for producing cyclopentylbenzene, wherein, Cyclopentylbenzene is synthesized by reacting benzene and cyclopentene with a catalyst. The catalyst is a monolithic binder-free MFI molecular sieve prepared by any one of claims 1-9 or a monolithic binder-free MFI molecular sieve as described in any one of claims 10-18.

22. The method according to claim 21, characterized in that, The molar ratio of benzene to cyclopentene is (1~5):

1.

23. The method according to claim 22, characterized in that, The molar ratio of benzene to cyclopentene is (1~3):

1.

24. The method according to claim 21, characterized in that, The reaction temperature is 150–300 °C, the reaction pressure is 0.8–1.5 MPa, and the weight hourly space velocity (WHSV) of cyclopentene is 0.05–2 h⁻¹. -1 .

25. The method according to claim 24, characterized in that, The reaction temperature is 150–250 °C, the reaction pressure is 0.9–1.2 MPa, and the weight hourly space velocity (WHSV) of cyclopentene is 0.05–1 h⁻¹. -1 .

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