Beta molecular sieve catalyst, preparation method and application thereof

Abstract

The application discloses a Beta molecular sieve catalyst and a preparation method and application thereof, and the preparation method comprises the following steps: a, under the condition of an ultra-concentration system, Na type Beta molecular sieve is prepared by using an alkali source, a potassium source, a zeolite, a silicon source and an organic template agent, and the silicon-aluminum ratio of the Na type Beta molecular sieve is 10-80; b, after ammonium ion exchange of the Na type Beta molecular sieve in an ammonium salt aqueous solution, H type Beta molecular sieve is prepared by washing, drying and calcining; and c, Beta molecular sieve catalyst is prepared by using the H type Beta molecular sieve, a matrix, an initiator and a lubricant. The application can significantly reduce the cost of preparing the Beta molecular sieve catalyst.

Description

Technical Field

[0001] This invention relates to a Beta molecular sieve catalyst, its preparation method and application, belonging to the field of molecular sieve catalyst technology. Background Technology

[0002] Styrene is a raw material for the production of polystyrene, styrene-butadiene rubber, and ABS resin. The synthesis of ethylbenzene is the first step in the production of styrene.

[0003] Ethylbenzene is typically produced using a liquid-phase alkylation method with aluminum trichloride as a catalyst and benzene and ethylene as raw materials, hereinafter referred to as the "aluminum trichloride method". The aluminum trichloride method has mild reaction conditions and low xylene impurity content in ethylbenzene products, but the method also has obvious disadvantages: environmental pollution, equipment corrosion, long process flow, and high energy consumption.

[0004] In the 1970s, ethylbenzene was produced using a gas-phase alkylation method on a molecular sieve catalyst with mesoporous ZSM-5 molecular sieves as catalysts and benzene and ethylene as raw materials. This method is referred to as the "ZSM-5 molecular sieve catalyst method". The ZSM-5 molecular sieve catalyst method overcame the shortcomings of the aluminum trichloride method and achieved industrialization. However, the ZSM-5 molecular sieve catalyst method has the disadvantages of high reaction temperature (>350℃) and high xylene impurity content in the product.

[0005] In the late 1980s, a new technology for producing ethylbenzene using liquid-phase alkylation with benzene and ethylene as raw materials was developed abroad. This new technology not only overcame the shortcomings of the aluminum trichloride method, but also had the advantages of milder reaction conditions, the ability to use carbon steel for all equipment materials, significantly reduced investment, shorter operating cycle, and maintaining low xylene impurity content in the liquid-phase ethylbenzene product.

[0006] US Patent USP4891458 reports the synthesis of ethylbenzene using a β-zeolite catalyst under liquid-phase alkylation reaction conditions, wherein the β-zeolite is an ammonium or rare-earth ion-exchange zeolite.

[0007] US Patent USP5227558 discloses a method for treating modified β-zeolites with steam. For β-zeolites with a SiO2 / Al2O3 ratio of 20 to 50, after ammonium exchange and calcination at 530 to 580°C to remove ammonium, they are treated with steam at 550 to 750°C to remove aluminum, and then subjected to ammonium ion exchange under acidic conditions. The modified zeolite has a SiO2 / Al2O3 ratio of 50 to 350, preferably 70 to 200. The resulting zeolite can be used for gas-phase alkylation to produce ethylbenzene and has the characteristic of very low xylene content in the ethylbenzene product. It can also be used for liquid-phase alkylation to produce ethylbenzene.

[0008] Chinese patent CN 101433859 proposes a phosphorus-containing β-molecular sieve with a phosphorus content of 0.01–10 wt% based on P2O5. The catalyst is obtained by calcining the β-molecular sieve in air at 450–700°C for 1–20 hours to remove the organic template agent, then treating it with an aqueous solution of a phosphorus-containing compound at 100–250°C to obtain the phosphorus-containing β-molecular sieve, and finally mixing it with an inorganic oxide support and calcining it.

[0009] Although benzene and ethylene alkylation catalysts with Beta zeolite as the active component exhibit high activity, there is room for improvement in terms of stability and product selectivity. Furthermore, post-treatment of the Beta zeolite catalyst or direct adjustment of the hydrothermal synthesis conditions to prepare more stable Beta zeolites are common improvement methods.

[0010] This invention provides a Beta molecular sieve catalyst, its preparation method, and its application. Summary of the Invention

[0011] The purpose of this invention is to overcome the shortcomings of the prior art and provide a Beta molecular sieve catalyst, its preparation method and application, which can not only reduce the process cost of preparing Beta molecular sieve catalyst, but also improve the performance of Beta molecular sieve catalyst.

[0012] To achieve the above objectives, the present invention is implemented using the following technical solution:

[0013] On one hand, the present invention provides a method for preparing a Beta molecular sieve catalyst, comprising the following steps:

[0014] a. Under ultra-concentrated system conditions, Na-type Beta molecular sieves were prepared using an alkali source, a potassium source, zeolite, a silicon source, and an organic template agent, wherein the silicon-to-aluminum ratio of the Na-type Beta molecular sieves was 10-80.

[0015] b. H-type Beta molecular sieve was prepared by exchanging Na-type Beta molecular sieve with ammonium ions in an ammonium salt aqueous solution, followed by washing, drying, and calcination.

[0016] c. Beta molecular sieve catalysts are prepared using H-type Beta molecular sieves, matrix, initiator, and lubricant.

[0017] Preferably, step a includes the following steps:

[0018] a1. An alkaline solution is obtained by mixing an alkaline source, a potassium source and deionized water.

[0019] a2 After adding zeolite to the alkaline solution and stirring until homogeneous, silicon source and organic template agent are added and stirred until homogeneous to obtain a mixed gel;

[0020] After gradient heating and crystallization of the mixed gel, a3 synthesized Na-type Beta molecular sieves with a silica-to-alumina ratio of 10-80 in an ultra-concentrated system.

[0021] Preferably, the silica-to-alumina ratio of the Na-type Beta molecular sieve is 15-60.

[0022] Preferably, in step a1, the molar ratio of K2O to Na2O in the alkaline solution is (0.1-0.5):1.

[0023] Preferably, in step a1, the concentration of (Na2O+K2O) in the alkaline solution is 20-50 wt%.

[0024] Preferably, in step a2, the molar ratio of (Na2O+K2O) in the alkaline solution to Al2O3 in the zeolite is (5-25):1.

[0025] Preferably, in step a2, the molar ratio of each component in the mixed gel is: (Na2O+K2O):SiO2:Al2O3:R:H2O=(5~25):(20~100):1:(0.5~3):(60~160), where R is an organic template agent.

[0026] Preferably, in step a3, the gradient heating crystallization of the mixed gel includes: pre-treating the mixed gel in a closed environment at a temperature of 60-100°C for 0.5-5 hours, then raising the temperature of the closed environment to 135-165°C and crystallizing the mixed gel for 6-24 hours.

[0027] Preferably, step b includes the following steps:

[0028] After exchanging ammonium ions 1 to 3 times in an ammonium salt aqueous solution, the Na-type Beta molecular sieve is washed, dried, and calcined to obtain the H-type Beta molecular sieve.

[0029] Preferably, during the ammonium ion exchange process in step b, the reaction system temperature is 30–110°C.

[0030] Preferably, in step b, the drying temperature is 100–140°C and the drying time is 2–5 hours.

[0031] Preferably, in step b, the roasting temperature is 450–550°C and the roasting time is 3–6 hours.

[0032] Preferably, step c includes the following steps:

[0033] After the matrix is ​​added to the H-type Beta molecular sieve and mixed evenly, the initiator is added and stirred evenly, and then an aqueous solution of lubricant is added and stirred evenly. The mixture is then kneaded, extruded, dried, and calcined to obtain the Beta molecular sieve catalyst.

[0034] Preferably, in step c: the solid weight ratio of H-type Beta molecular sieve, matrix, and lubricant is (30-60):(50-35):(20-5), and the mass of initiator is 0.2%-5% of the total solid mass, wherein the total solid mass is the solid mass of molecular sieve, matrix, and lubricant;

[0035] Preferably, in step c, the drying process is carried out at a temperature of 100–140°C for 2–5 hours.

[0036] Preferably, in step c, the roasting temperature is 500–650°C and the roasting time is 3–6 hours.

[0037] Preferably, the alkali source is sodium hydroxide.

[0038] Preferably, the potassium source is selected from one or a combination of potassium hydroxide, potassium peroxide, potassium carbonate, potassium bicarbonate, and potassium chloride.

[0039] Preferably, the potassium source is potassium hydroxide.

[0040] Preferably, the zeolite is zeolite A or zeolite X;

[0041] Preferably, the silicon source is selected from one or a combination of several of the following: silica, tetraethyl orthosilicate, water glass, and silica sol.

[0042] Preferably, the silicon source is silica sol.

[0043] Preferably, the organic template agent is one of tetraethylammonium hydroxide, tetraethylammonium chloride, and tetraethylammonium bromide.

[0044] Preferably, the organic template agent is tetraethylammonium hydroxide.

[0045] Preferably, the ammonium salt aqueous solution is one of 0.5-5 mol / L ammonium nitrate aqueous solution, ammonium sulfate aqueous solution, ammonium chloride aqueous solution, and ammonium bicarbonate aqueous solution.

[0046] Preferably, the ammonium salt aqueous solution is one of 1-3 mol / L ammonium nitrate aqueous solution, ammonium sulfate aqueous solution, ammonium chloride aqueous solution, and ammonium bicarbonate aqueous solution.

[0047] Preferably, the matrix is ​​selected from one or a combination of several of kaolin, attapulgite, diatomite, and boehmite.

[0048] Preferably, the matrix is ​​boehmite.

[0049] Preferably, the lubricant is guar gum powder and / or methylcellulose.

[0050] Preferably, the aqueous solution concentration of the lubricant is 10–30 wt%.

[0051] Preferably, the aqueous solution concentration of the lubricant is 15-20 wt%.

[0052] Preferably, the initiator is an aqueous solution prepared from an acid and ammonium metatungstate, wherein the concentration of the acid is 5-30 wt% and the concentration of the ammonium metatungstate is 5-15 wt%.

[0053] The acid is selected from one or more of concentrated nitric acid, concentrated sulfuric acid, concentrated hydrochloric acid, and concentrated phosphoric acid;

[0054] The concentration of the ammonium metatungstate is 5–15 wt%.

[0055] Preferably, the concentration of acid in the initiator is 15–20 wt%.

[0056] Preferably, the acid is concentrated nitric acid.

[0057] On the other hand, the present invention provides a Beta molecular sieve catalyst obtained according to the above-described method for preparing the Beta molecular sieve catalyst. Furthermore, the present invention provides the application of the Beta molecular sieve catalyst obtained according to the above-described method, or the Beta molecular sieve catalyst described above, in the high-space-velocity liquid-phase alkylation reaction of benzene and ethylene to prepare ethylbenzene. The evaluation conditions are characterized by: a fixed-bed reactor, a loading volume of 10 ml, a reaction temperature of 250 °C, a reaction pressure of 3.5 MPa, a benzene / ethylene molar ratio of 4, and a benzene volume hourly space velocity of 8 h⁻¹. -1 .

[0058] Compared with the prior art, the beneficial effects achieved by the present invention are as follows:

[0059] This invention uses inexpensive zeolite as raw material to synthesize Beta molecular sieves via a crystallization method. The inexpensive zeolite can not only participate in the reaction as a silicon-aluminum raw material, but also provide the secondary structural units required for the synthesis of Beta molecular sieves—single four-membered rings and single six-membered rings. This shortens the reaction time and reduces the amount of organic template agent used, thereby reducing the synthesis cost of Beta molecular sieves and reducing energy consumption.

[0060] This invention introduces potassium ions to adjust the particle size of Beta molecular sieves and improve their crystallinity, thereby achieving the synthesis of Na-type Beta zeolite products with a silicon-to-aluminum ratio of 10 to 80 and good crystallinity in a shorter time, thus further reducing the synthesis cost of Beta molecular sieves.

[0061] In the catalyst forming process, this invention optimizes the acidity of the catalyst and increases its mesoporous channels by adding acid and ammonium metatungstate. In addition, the introduction of tungsten can reduce the formation of side reactions such as diethylbenzene and triethylbenzene, thereby improving the selectivity of ethylbenzene and the conversion rate of ethylene.

[0062] In the catalyst extrusion process, the present invention introduces a lubricant to make the outer surface of the strip smooth. In addition, the lubricant used in this application is an organic material, which, after calcination, can make the internal channels of the Beta molecular sieve catalyst abundant and have high strength.

[0063] The preparation process of this invention is carried out under ultra-concentrated system conditions, which can reduce water consumption and significantly reduce the amount of wastewater in the reaction system. At the same time, it can meet the pH requirements of the Beta molecular sieve synthesis system with less organic template agent and alkali.

[0064] This invention eliminates the need to introduce fluoride ions during the synthesis of Beta molecular sieves, making it environmentally friendly.

[0065] Compared with existing technologies, the Beta molecular sieve catalyst prepared in this invention exhibits higher ethylbenzene selectivity and significantly improved activity stability in the high-space-velocity liquid-phase alkylation reaction of benzene and ethylene to produce ethylbenzene. Attached Figure Description

[0066] Figure 1 This is an electron micrograph of the Na-type Beta molecular sieve prepared in Example 1 of the present invention;

[0067] Figure 2 This is an electron micrograph of the Na-type Beta molecular sieve prepared in Example 2 of the present invention;

[0068] Figure 3 This is an electron micrograph of the Na-type Beta molecular sieve prepared in Example 3 of the present invention;

[0069] Figure 4 This is an electron micrograph of the Na-type Beta molecular sieve prepared in Example 4 of the present invention;

[0070] Figure 5 This is an electron micrograph of the Na-type Beta molecular sieve prepared in Example 5 of the present invention;

[0071] Figure 6 This is an electron micrograph of the Na-type Beta molecular sieve prepared in Example 6 of the present invention;

[0072] Figure 7 This is an electron microscope image of the Na-type Beta molecular sieve prepared in Comparative Example 1 of this invention.

[0073] Figure 8 The crystal phase diagram is shown for the Na-type Beta molecular sieve prepared in Example 5 of this invention. Detailed Implementation

[0074] The present invention will be further described below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and should not be used to limit the scope of protection of the present invention.

[0075] Beta zeolite possesses a three-dimensional twelve-membered ring cross-channel structure. Due to its unique structure and excellent thermal and hydrothermal stability, it is used in petroleum refining and petrochemical processes such as hydrocracking, hydroisomerization, aromatic alkylation, and olefin hydration, making it an important industrial zeolite molecular sieve. However, the high cost of synthesizing Beta zeolite, requiring a large amount of organic template agent, limits its widespread application.

[0076] This invention introduces a method for preparing Beta molecular sieve catalysts, which can reduce the preparation cost of Beta molecular sieve catalysts.

[0077] This invention discloses a method for preparing a Beta molecular sieve catalyst, characterized by comprising the following steps:

[0078] a. Under ultra-concentrated system conditions, Na-type Beta molecular sieves are prepared using an alkali source, a potassium source, zeolite, a silicon source, and an organic template agent. The silicon-to-aluminum ratio of the Na-type Beta molecular sieves is 10-80.

[0079] When applying, step a includes the following:

[0080] a1 is prepared by mixing an alkaline source, a potassium source, and deionized water to obtain an alkaline solution.

[0081] The molar ratio of K2O to Na2O in the alkaline solution is (0.1~0.5):1.

[0082] The concentration of (Na₂O + K₂O) in the alkaline solution is 20–50 wt%.

[0083] When used, the alkali source is sodium hydroxide; the potassium source is selected from one or a combination of potassium hydroxide, potassium peroxide, potassium carbonate, potassium bicarbonate, and potassium chloride.

[0084] In some preferred embodiments, the potassium source is potassium hydroxide.

[0085] After adding zeolite to the alkaline solution and stirring until homogeneous, a2 continues to add silicon source and organic template agent and stir until homogeneous to obtain a mixed gel.

[0086] The molar ratio of (Na2O+K2O) in the alkaline solution to Al2O3 in the zeolite is (5~25):1.

[0087] The molar ratio of each component in the mixed gel is: (Na2O+K2O):SiO2:Al2O3:R:H2O=(5~25):(20~100):1:(0.5~3):(60~160), where R is an organic template agent.

[0088] When applying, the zeolite is either zeolite A or zeolite X; the silicon source is selected from one or a combination of several of the following: silica, tetraethyl orthosilicate, water glass, and silica sol; the organic template agent R is one of tetraethylammonium hydroxide, tetraethylammonium chloride, and tetraethylammonium bromide.

[0089] In some preferred embodiments, the silicon source is silica sol; the organic template agent is tetraethylammonium hydroxide.

[0090] After gradient heating and crystallization of the mixed gel, a3 synthesized Na-type Beta molecular sieves with a silica-to-alumina ratio of 10-80 in an ultra-concentrated system.

[0091] In some preferred embodiments, the silica-to-alumina ratio of the Na-type Beta molecular sieve is 15-60.

[0092] When applying the mixture, gradient heating crystallization includes: pre-treating the mixture in a closed environment at a temperature of 60-100°C for 0.5-5 hours, then raising the temperature of the closed environment to 135-165°C and crystallizing the mixture for 6-24 hours.

[0093] b. Prepare H-type Beta molecular sieve by performing ammonium ion exchange in an ammonium salt aqueous solution using Na-type Beta molecular sieve;

[0094] Step b includes the following steps:

[0095] After exchanging ammonium ions 1 to 3 times in an ammonium salt aqueous solution, Na-type Beta molecular sieves are dried and calcined to obtain H-type Beta molecular sieves.

[0096] During application, the reaction system temperature is 30–110℃ during the ammonium ion exchange process; the drying temperature is 100–140℃ and the drying time is 2–5h during the drying process in step b; the calcination temperature is 450–550℃ and the calcination time is 3–6h during the calcination process in step b.

[0097] In practical applications, the ammonium salt aqueous solution is one of the following: 0.5–5 mol / L ammonium nitrate aqueous solution, ammonium sulfate aqueous solution, ammonium chloride aqueous solution, or ammonium bicarbonate aqueous solution.

[0098] In some preferred embodiments, the ammonium salt aqueous solution is one of 1-3 mol / L ammonium nitrate aqueous solution, ammonium sulfate aqueous solution, ammonium chloride aqueous solution, and ammonium bicarbonate aqueous solution.

[0099] c. Beta molecular sieve catalysts are prepared using H-type Beta molecular sieves, matrix, initiator, and lubricant.

[0100] Step c includes the following steps:

[0101] After the matrix is ​​added to the H-type Beta molecular sieve and mixed evenly, the initiator is added and mixed evenly, the lubricant aqueous solution is added and mixed evenly, and then the mixture is kneaded, extruded, dried and calcined to obtain the Beta molecular sieve catalyst.

[0102] The solid weight ratio of H-type Beta molecular sieve, matrix, and lubricant is (30-60):(50-35):(20-5), and the mass of initiator is 0.2%-5% of the total solid mass, wherein the total solid mass is the solid mass of molecular sieve, matrix, and lubricant.

[0103] In addition, during step c: during the drying process, the drying temperature is 100-140℃ and the drying time is 2-5h; during the calcination process, the calcination temperature is 500-650℃ and the calcination time is 3-6h.

[0104] When applied, the matrix is ​​selected from one or a combination of several of kaolin, attapulgite, diatomite, and pseudoboehmite; the lubricant is guar gum powder and / or methylcellulose; the initiator is an aqueous solution of acid and ammonium metatungstate, wherein the concentration of acid is 5-30 wt% and the concentration of ammonium metatungstate is 5-15 wt%.

[0105] The concentration of the aqueous solution of the lubricant is 10–30 wt%. The acid is selected from one or more combinations of concentrated nitric acid, concentrated sulfuric acid, concentrated hydrochloric acid, and concentrated phosphoric acid, with a concentration of 65–68 wt% for concentrated nitric acid, 98 wt% for concentrated sulfuric acid, 36.5 wt% for concentrated hydrochloric acid, and 85 wt% for concentrated phosphoric acid.

[0106] In some preferred embodiments, the aqueous solution concentration of the lubricant is 15–20 wt%.

[0107] In some preferred embodiments, the concentration of acid in the initiator is 15–20 wt%.

[0108] In some preferred embodiments, the acid is concentrated nitric acid with a concentration of 65-68 wt%.

[0109] In some preferred embodiments, the matrix is ​​boehmite.

[0110] This application describes the Beta molecular sieve catalyst prepared according to the above-described method.

[0111] Furthermore, this application relates to the application of the Beta molecular sieve catalyst obtained according to the above-described method for preparing the Beta molecular sieve catalyst, or the application of the above-described Beta molecular sieve catalyst in the high-space-velocity liquid-phase alkylation reaction of benzene and ethylene to prepare ethylbenzene.

[0112] The evaluation conditions were: fixed-bed reactor, 10 ml loading volume, reaction temperature 250℃, reaction pressure 3.5 MPa, benzene / ethylene molar ratio 4, and benzene volume hourly space velocity 8 h⁻¹. -1 .

[0113] 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. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0114] The following instruments were used in the test results of this application:

[0115] Scanning electron microscope: used for molecular sieve particle size and morphology analysis;

[0116] Physical adsorption apparatus: used for testing specific surface area, microporous specific surface area, and mesoporous specific surface area;

[0117] X-ray diffractometer: used for relative crystallinity and crystal structure analysis;

[0118] Particle strength tester: used to determine compressive strength.

[0119] Example 1

[0120] Preparation of Na-type Beta molecular sieves

[0121] a1. Mix the alkali source, potassium source and deionized water to form a 20wt% alkali solution.

[0122] In this embodiment, the alkali source is sodium hydroxide (industrial grade, 98 wt%), and the potassium source is potassium hydroxide (industrial grade, 91 wt%).

[0123] a2. Zeolite was added to an alkaline solution, and after stirring and mixing, a silicon source and a small amount of organic template agent were added and mixed evenly to obtain a mixed gel.

[0124] The molar ratio of K2O to Na2O in the alkaline solution is 0.1:1, the molar ratio of (Na2O+K2O) to Al2O3 in the zeolite is 5:1, and the molar ratio of each component in the mixed gel is: (Na2O+K2O):SiO2:Al2O3:R:H2O=25:20:1:0.5:60.

[0125] In this embodiment, the zeolite is zeolite A, the silicon source is silica sol (industrial grade, 30 wt%), and the organic template agent is tetraethylammonium hydroxide (industrial grade, 25 wt%).

[0126] When applying zeolite, since it contains both Si and Al elements, the Si and Al content in the zeolite must be considered when adding other ingredients. In this example, the SiO2:Al2O3 molar ratio in zeolite A is 1.5 (X-ray fluorescence spectrometry, abbreviated as XRF).

[0127] a3 loaded the mixed gel into a high-pressure reactor and pretreated it in a closed environment at 100°C for 0.5 h. Then, the closed environment temperature was raised to 135°C and crystallized for 24 h. After cooling to room temperature, the mixture was filtered, washed, and synthesized in an ultra-concentrated system with a silicon-to-aluminum ratio of 18.3, forming a Na-type Beta molecular sieve.

[0128] The electron microscopy structure of the Na-type Beta molecular sieve with a silicon-to-aluminum ratio of 18.3 prepared in this embodiment is shown in the figure. Figure 1 .

[0129] b. Preparation of H-type Beta molecular sieves

[0130] The Na-type Beta molecular sieve obtained in step a was placed in an ammonium salt aqueous solution and subjected to ammonium ion exchange once at 110℃. After washing, it was dried at 140℃ for 2 hours and calcined at 550℃ for 3 hours to obtain the H-type Beta molecular sieve.

[0131] The ammonium salt aqueous solution in this embodiment is a 1 mol / L ammonium bicarbonate aqueous solution.

[0132] c. Preparation of Beta molecular sieve catalysts

[0133] After mechanically mixing the H-type Beta molecular sieve obtained in step b with the matrix, an initiator was added and mixed evenly. Then, an aqueous solution of lubricant was added, and the mixture was kneaded and extruded into strips. The mixture was then subjected to drying treatment at 140°C for 2 hours and calcination treatment at 650°C for 3 hours to obtain the Beta molecular sieve catalyst.

[0134] The solid mass ratio of H-type Beta molecular sieve, matrix, and lubricant is 30:50:20, the initiator accounts for 0.2% of the total solid mass, and the lubricant accounts for 15% of the total solid mass.

[0135] The matrix in this embodiment is boehmite (industrial grade, Al2O3≥65wt%); the lubricant is a 15wt% guar gum powder solution; the initiator is prepared from 65wt% concentrated nitric acid, ammonium metatungstate and deionized water, wherein the concentration of nitric acid in the initiator is 15wt% and the concentration of ammonium metatungstate is 5wt%.

[0136] The molecular sieve obtained in this embodiment has a particle size of 0.4–0.5 μm, a relative crystallinity of 132%, and a specific surface area of ​​580 m² for the strip-shaped Beta molecular sieve catalyst. 2 / g, S meso / S micro =15.6, where S meso S is the surface area of ​​the mesopores. micro The surface area of ​​the micropores is 62 N / cm, and the compressive strength is 62 N / cm.

[0137] The strip-shaped Beta molecular sieve catalyst obtained in this embodiment was evaluated in a fixed-bed reactor for styrene liquid-phase alkylation reaction. The evaluation conditions were: fixed-bed reactor, 10 ml loading, reaction temperature 250 °C, reaction pressure 3.5 MPa, benzene / ethylene molar ratio 4, and benzene volume hourly space velocity 8 h⁻¹. -1 For details, please refer to Table 1.

[0138] Table 1 Evaluation of Beta molecular sieve catalysts in styrene liquid-phase alkylation reaction in a fixed-bed reactor

[0139]

[0140] Example 2

[0141] The difference between this embodiment and Embodiment 1 is that:

[0142] Preparation of Na-type Beta molecular sieves

[0143] In step a1: the concentration of the alkaline solution is 50 wt%; the molar ratio of K2O to Na2O in the alkaline solution is 0.5:1.

[0144] In step a2: the molar ratio of each component in the mixed gel is: (Na2O+K2O):SiO2:Al2O3:R:H2O=25:100:1:3:160.

[0145] In step a3: the process of gradient heating and crystallization of the mixed gel: the mixed gel is loaded into a high-pressure reactor and pretreated in a closed environment at 60°C for 5 hours. Then, the temperature of the closed environment is raised to 165°C and crystallized for 6 hours. After cooling to room temperature, the mixture is filtered, washed, and synthesized in an ultra-concentrated system with a silicon-to-aluminum ratio of 79.8.

[0146] The electron microscopy structure of the Na-type Beta molecular sieve with a silicon-to-aluminum ratio of 79.8 prepared in this embodiment is shown in the figure. Figure 2 .

[0147] b. Preparation of H-type Beta molecular sieves

[0148] The Na-type Beta molecular sieve obtained in step a was placed in an ammonium salt aqueous solution and subjected to ammonium ion exchange three times at 30°C. Then, it was dried at 100°C for 5 hours and calcined at 450°C for 6 hours to obtain the H-type Beta molecular sieve.

[0149] The ammonium salt aqueous solution in this embodiment is a 2 mol / L ammonium nitrate aqueous solution.

[0150] c. Preparation of Beta molecular sieve catalysts

[0151] In step c, the drying temperature is 100℃ and the time is 5h; the calcination temperature is 500℃ and the time is 6h.

[0152] The solid mass ratio of H-type Beta molecular sieve, matrix, and lubricant is 60:35:5, the mass of initiator is 5% of the total solid mass, and the mass of lubricant is 10% of the total solid mass.

[0153] In this embodiment, the initiator is prepared from 98wt% concentrated sulfuric acid, ammonium metatungstate and deionized water. The sulfuric acid concentration in the initiator is 10wt% and the ammonium metatungstate concentration is 15wt%.

[0154] The molecular sieve obtained in this embodiment has a particle size of 1–1.5 μm, a relative crystallinity of 165%, and a specific surface area of ​​584 m² for the strip-shaped Beta molecular sieve catalyst. 2 / g, S meso / S micro =21.9, where S meso S is the surface area of ​​the mesopores. micro The surface area of ​​the micropores is 60.5 N / cm, and the compressive strength is 60.5 N / cm.

[0155] The strip-shaped Beta molecular sieve catalyst obtained in this embodiment was evaluated in a fixed-bed reactor for styrene liquid-phase alkylation reaction. The specific results are detailed in Table 1.

[0156] Example 3

[0157] The difference between this embodiment and Embodiment 1 is that:

[0158] Preparation of Na-type Beta molecular sieves

[0159] In step a1: the potassium source is potassium chloride, and the ratio of K2O:Na2O in the alkaline solution is 0.3:1.

[0160] In step a2: the molar ratio of (Na2O+K2O) in the alkaline solution to Al2O3 in the zeolite is 15:1, and the molar ratio of each component in the mixed gel is: (Na2O+K2O):SiO2:Al2O3:R:H2O=15:80:1:1.5:100.

[0161] In step a3: the process of gradient heating and crystallization of the mixed gel: the mixed gel is loaded into a high-pressure reactor and pretreated in a closed environment at 100°C for 3 hours. Then, the temperature of the closed environment is raised to 160°C and crystallized for 12 hours. After cooling to room temperature, the mixture is filtered, washed, and synthesized in an ultra-concentrated system with a silicon-to-aluminum ratio of 75.1, forming a Na-type Beta molecular sieve.

[0162] The electron microscopy structure of the Na-type Beta molecular sieve with a silicon-to-aluminum ratio of 75.1 prepared in this embodiment is shown in the figure. Figure 3 .

[0163] b. Preparation of H-type Beta molecular sieves

[0164] The ammonium ion exchange process in step b: The Na-type Beta molecular sieve obtained in step a is placed in an ammonium salt aqueous solution and ammonium ion exchange is performed twice at 80℃.

[0165] The ammonium salt aqueous solution in this embodiment is a 3 mol / L ammonium nitrate aqueous solution.

[0166] c. Preparation of Beta molecular sieve catalysts

[0167] In step c, the solid mass ratio of H-type Beta molecular sieve, matrix, and lubricant is 50:40:10, the mass of initiator is 1% of the total solid mass, and the mass of lubricant is 10% of the total solid mass.

[0168] In this embodiment, the matrix is ​​attapulgite (industrial grade, solid content 87%), the lubricant is methylcellulose, and it is prepared as an aqueous solution with a concentration of 30wt%. The initiator is prepared by 36.5wt% concentrated hydrochloric acid, ammonium metatungstate and deionized water, with the hydrochloric acid concentration in the initiator being 30wt% and the ammonium metatungstate concentration being 10wt%.

[0169] The molecular sieve obtained in this embodiment has a particle size of 0.5–0.6 μm, a relative crystallinity of 151%, and a specific surface area of ​​579 m² for the strip-shaped Beta molecular sieve catalyst. 2 / g, S meso / S micro =18.5, where S meso S is the surface area of ​​the mesopores. micro The surface area of ​​the micropores is 68.2 N / cm, and the compressive strength is 68.2 N / cm.

[0170] The strip-shaped Beta molecular sieve catalyst obtained in this embodiment was evaluated in a fixed-bed reactor for styrene liquid-phase alkylation reaction. The specific results are detailed in Table 1.

[0171] Example 4

[0172] The difference between this embodiment and Embodiment 1 is that:

[0173] Preparation of Na-type Beta molecular sieves

[0174] In step a1: the concentration of the alkaline solution is 30 wt%; the molar ratio of K2O to Na2O in the alkaline solution is 0.2:1.

[0175] In step a2: the silicon source is silica, the molar ratio of (Na2O+K2O) in the alkaline solution to Al2O3 in the zeolite is 18:1, and the molar ratio of each component in the mixed gel is: (Na2O+K2O):SiO2:Al2O3:R:H2O=18:60:1:1:100.

[0176] In step a3: the process of gradient heating and crystallization of the mixed gel: the mixed gel is loaded into a high-pressure reactor and pretreated in a closed environment at 100°C for 2 hours. Then, the temperature of the closed environment is raised to 165°C and crystallized for 6 hours. After cooling to room temperature, the mixture is filtered, washed, and synthesized in an ultra-concentrated system with a silicon-to-aluminum ratio of 55.3, forming a Na-type Beta molecular sieve.

[0177] The electron microscopy structure of the Na-type Beta molecular sieve with a silicon-to-aluminum ratio of 55.3 prepared in this embodiment is shown in the figure. Figure 4 .

[0178] b. Preparation of H-type Beta molecular sieves

[0179] The ammonium ion exchange process in step b: The Na-type Beta molecular sieve obtained in step a is placed in an ammonium salt aqueous solution and ammonium ion exchange is performed twice at 80℃.

[0180] The roasting time in step b is 6 hours.

[0181] The ammonium salt aqueous solution in this embodiment is a 1 mol / L ammonium chloride aqueous solution.

[0182] c. Preparation of Beta molecular sieve catalysts

[0183] In step c

[0184] The solid mass ratio of H-type Beta molecular sieve, matrix, and lubricant is 50:35:15, the mass of initiator is 1% of the total solid mass, and the mass of lubricant is 10% of the total solid mass.

[0185] In this embodiment, the matrix is ​​kaolin (industrial grade, solid content 85%), the lubricant is methylcellulose, and it is prepared as an aqueous solution with a concentration of 15wt%. The initiator is composed of 85wt% concentrated phosphoric acid, ammonium metatungstate and deionized water, wherein the concentration of phosphoric acid is 15wt% and the concentration of ammonium metatungstate is 10wt%.

[0186] The molecular sieve obtained in this embodiment has a particle size of 0.3–0.4 μm, a relative crystallinity of 142%, and a specific surface area of ​​586 m² for the strip-shaped Beta molecular sieve catalyst. 2 / g, S meso / S micro =14.8, where S meso S is the surface area of ​​the mesopores. micro The surface area of ​​the micropores is 65.3 N / cm, and the compressive strength is 65.3 N / cm.

[0187] The strip-shaped Beta molecular sieve catalyst obtained in this embodiment was evaluated in a fixed-bed reactor for styrene liquid-phase alkylation reaction. The specific results are detailed in Table 1.

[0188] Example 5

[0189] The difference between this embodiment and Embodiment 1 is that:

[0190] Preparation of Na-type Beta molecular sieves

[0191] In step a1: the molar ratio of K2O to Na2O in the alkaline solution is 0.3:1.

[0192] In step a2: the silicon source is silica, the molar ratio of (Na2O+K2O) in the alkaline solution to Al2O3 in the zeolite is 18:1, and the molar ratio of each component in the mixed gel is: (Na2O+K2O):SiO2:Al2O3:R:H2O=15:40:1:1.2:100.

[0193] In step a3: the process of gradient heating and crystallization of the mixed gel: the mixed gel is loaded into a high-pressure reactor and pretreated in a closed environment at 100°C for 2 hours. Then, the temperature of the closed environment is raised to 165°C and crystallized for 12 hours. After cooling to room temperature, the mixture is filtered, washed, and synthesized in an ultra-concentrated system with a silicon-to-aluminum ratio of 38.6, forming a Na-type Beta molecular sieve.

[0194] The electron microscopy structure of the Na-type Beta molecular sieve with a silicon-to-aluminum ratio of 38.6 prepared in this embodiment is shown in the figure. Figure 5 The crystal phase diagram of the Na-type Beta molecular sieve with a silicon-to-aluminum ratio of 38.6 prepared in this embodiment is shown in the attached diagram. Figure 8 .

[0195] b. Preparation of H-type Beta molecular sieves

[0196] The ammonium ion exchange process in step b: The Na-type Beta molecular sieve obtained in step a is placed in an ammonium salt aqueous solution and ammonium ion exchange is performed twice at 80℃.

[0197] The ammonium salt aqueous solution in this embodiment is a 2 mol / L ammonium sulfate aqueous solution.

[0198] c. Preparation of Beta molecular sieve catalysts

[0199] In step c

[0200] The solid mass ratio of H-type Beta molecular sieve, matrix, and lubricant is 50:40:10, the mass of initiator is 2% of the total solid mass, and the mass of lubricant is 10% of the total solid mass.

[0201] In this embodiment, the initiator is prepared from 65wt% concentrated nitric acid, ammonium metatungstate and deionized water, with the concentration of concentrated nitric acid in the initiator being 10wt% and the concentration of ammonium metatungstate being 8wt%.

[0202] The molecular sieve obtained in this embodiment has a particle size of 1–1.5 μm, a relative crystallinity of 136%, and a specific surface area of ​​581 m² for the strip-shaped Beta molecular sieve catalyst. 2 / g, S meso / S micro =23.5, where S meso S is the surface area of ​​the mesopores. micro The surface area of ​​the micropores is 63.8 N / cm, and the compressive strength is 63.8 N / cm.

[0203] The strip-shaped Beta molecular sieve catalyst obtained in this embodiment was evaluated in a fixed-bed reactor for styrene liquid-phase alkylation reaction. The specific results are detailed in Table 1.

[0204] Example 6

[0205] The difference between this embodiment and embodiment 5 is as follows:

[0206] Preparation of Na-type Beta molecular sieves

[0207] In step a2: the zeolite is X zeolite, and in this embodiment, the molar ratio of SiO2:Al2O3 in X zeolite is approximately 1.2.

[0208] c. Preparation of Beta molecular sieve catalysts

[0209] The specific surface area of ​​the strip-shaped Beta molecular sieve catalyst obtained in step c is 592 m². 2 / g, S meso / S micro =19.7, where S meso S is the surface area of ​​the mesopores. micro The surface area of ​​the micropores is 68.7 N / cm, and the compressive strength is 68.7 N / cm.

[0210] The electron microscopy structure of the Na-type Beta molecular sieve prepared in this embodiment, with a particle size of 1–1.5 μm, a relative crystallinity of 128%, and a silica-to-alumina ratio of 38.1, is shown in [reference needed]. Figure 6 .

[0211] The matrix in this embodiment is diatomaceous earth (industrial grade, solid content 85%). The strip-shaped Beta molecular sieve catalyst obtained in this embodiment was evaluated for styrene liquid-phase alkylation reaction in a fixed-bed reactor. The specific results are detailed in Table 1.

[0212] Comparative Example 1

[0213] Preparation of Na-type Beta molecular sieves

[0214] According to the method disclosed in the embodiments of US Patent 3308069, Beta zeolite reference material, namely Na-type Beta molecular sieve, is synthesized using tetraethylammonium hydroxide as a template agent system. The specific steps are as follows:

[0215] First, a solution was prepared by mixing 0.10g of NaAlO2 (chemically pure, Al2O3, 41wt%) solid with 3.62g of TEAOH solution (industrial grade, 20wt%). Then, 3.28g of silica sol (industrial grade, SiO2 ≥ 30wt%) was added to the solution under vigorous stirring. The mixture was stirred until homogeneous to form a mixed gel, and stirring was continued for about 1 hour. The resulting mixed gel was then placed in a stainless steel reactor with a polytetrafluoroethylene liner and crystallized at 150℃ for about 4 days. After cooling to room temperature, the mixture was filtered and washed to synthesize a Na-type Beta molecular sieve with a silicon-to-aluminum ratio of 38.4.

[0216] The molar ratios of the components in the mixed gel are as follows: SiO2 / Al2O3 = 40, Na2O / SiO2 = 0.004, TEA2O / SiO2 = 0.15, and H2O / SiO2 = 17.6.

[0217] The Na-type Beta molecular sieve prepared in this comparative example has a silica-to-alumina ratio of 38.4 and a particle size of approximately 0.02–0.05 μm. Its crystallinity was set to 100%. Its electron microscopy structure is shown in [reference needed]. Figure 7 .

[0218] In this comparative example, the preparation of Na-type Beta molecular sieves did not use inexpensive zeolites, the amount of template agent was relatively high, K+ was not introduced, the amount of water used in the synthesis system was relatively large, and the reaction time was long.

[0219] b. Preparation of H-type Beta molecular sieve, same as in Example 1.

[0220] c. Prepare Beta molecular sieve catalysts in the same manner as in Example 1, but without adding initiators and lubricants.

[0221] The specific surface area of ​​the strip-shaped Beta molecular sieve catalyst obtained in this comparative example is 506 m². 2 / g, Smeso / Smicro=0.86, where S meso S is the surface area of ​​the mesopores. micro The surface area of ​​the micropores is 30 N / cm, and the compressive strength is 30 N / cm.

[0222] The strip-shaped Beta molecular sieve catalyst obtained in this comparative example was evaluated in a fixed-bed reactor for the liquid-phase alkylation reaction of styrene. The evaluation conditions were: fixed-bed reactor, 10 ml loading, reaction temperature 250 °C, reaction pressure 3.5 MPa, benzene / ethylene molar ratio 4, and benzene volume hourly space velocity 8 h⁻¹. -1 For details, please refer to Table 1.

[0223] Comparative Example 2

[0224] This comparative example prepared a Beta molecular sieve catalyst according to the preparation method described in Example 1. The difference from Example 1 is that no initiator and lubricant were added.

[0225] The molecular sieves obtained in this comparative example have a particle size of 0.4–0.5 μm, a relative crystallinity of 132%, and a specific surface area of ​​575 m² for the strip-shaped Beta molecular sieve catalyst. 2 / g, Smeso / Smicro=11.1, where S meso S is the surface area of ​​the mesopores. micro The surface area of ​​the micropores is 34 N / cm, and the compressive strength is 34 N / cm.

[0226] The strip-shaped Beta molecular sieve catalyst obtained in this comparative example was evaluated in a fixed-bed reactor for styrene liquid-phase alkylation reaction. The specific results are detailed in Table 1.

[0227] Comparative Example 3

[0228] This comparative example prepared a Beta molecular sieve catalyst according to the preparation method described in Example 5. The difference from Example 5 is that K is not introduced. + .

[0229] The molecular sieves obtained in this comparative example have a particle size of 0.05–0.1 μm, a relative crystallinity of 113%, and a specific surface area of ​​540 m² for the strip-shaped Beta molecular sieve catalyst. 2 / g, Smeso / Smicro=5.3, where S meso S is the surface area of ​​the mesopores. micro The surface area of ​​the micropores is 62.5 N / cm, and the compressive strength is 62.5 N / cm.

[0230] The strip-shaped Beta molecular sieve catalyst obtained in this comparative example was evaluated in a fixed-bed reactor for styrene liquid-phase alkylation reaction. The specific results are detailed in Table 1.

[0231] As can be seen from Examples 1-6 and Comparative Examples 1-3, this invention, under ultra-concentrated synthesis conditions, uses inexpensive zeolite as a raw material to prepare Beta molecular sieves via a crystallization method. Simultaneously, by introducing potassium, the particle size of the Beta molecular sieve is adjusted to improve its crystallinity, achieving the synthesis of Na-type Beta zeolite products with a silicon-to-aluminum ratio of 10-80 and good crystallinity in a relatively short time. The introduction of zeolite significantly reduces the amount of organic template agent used, thereby greatly reducing the synthesis cost of the Beta molecular sieve catalyst. Furthermore, the small amount of final mother liquor in the preparation process reduces environmental treatment costs.

[0232] As shown in Table 1, compared with the prior art, the Beta molecular sieve catalyst of the present invention has higher ethylbenzene selectivity and significantly improved activity stability in the high-space-velocity liquid-phase alkylation reaction of benzene and ethylene to prepare ethylbenzene.

[0233] In summary, this application can not only reduce the process cost of preparing Beta molecular sieve catalysts, but also improve the performance of Beta molecular sieve catalysts.

[0234] The crystallinity settings of the embodiments and comparative examples in this application are all based on the crystallinity of the molecular sieve in Comparative Example 1.

[0235] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a Beta molecular sieve catalyst, characterized in that, Includes the following steps: a. Under ultra-concentrated system conditions, Na-type Beta molecular sieves are prepared using an alkali source, a potassium source, zeolite, a silicon source, and an organic template agent. The Si / A ratio of the Na-type Beta molecular sieve is 10-80. Specifically, the preparation includes: a1. An alkaline solution is obtained by mixing an alkaline source, a potassium source and deionized water. a2 After adding zeolite to the alkaline solution and stirring until homogeneous, silicon source and organic template agent are added and stirred until homogeneous to obtain a mixed gel; After gradient heating and crystallization of the mixed gel, a3 synthesized Na-type Beta molecular sieves with a silica-to-alumina ratio of 10-80 in an ultra-concentrated system. In step a2, the molar ratio of each component in the mixed gel is: (Na2O+K2O):SiO2:Al2O3:R:H2O=(5~25):(20~100):1:(0.5~3):(60~160), where R is an organic template agent; In step a3, the gradient heating crystallization of the mixed gel includes: pre-treating the mixed gel in a closed environment at a temperature of 60~100℃ for 0.5~5h, then raising the temperature of the closed environment to 135~165℃ and crystallizing the mixed gel for 6~24h. The zeolite is either zeolite A or zeolite X; b. H-type Beta molecular sieve was prepared by exchanging Na-type Beta molecular sieve with ammonium ions in an ammonium salt aqueous solution, followed by washing, drying, and calcination. c. A Beta molecular sieve catalyst is prepared using H-type Beta molecular sieve, matrix, initiator, and lubricant. The initiator is an aqueous solution of acid and ammonium metatungstate, wherein the acid concentration is 5-30 wt% and the ammonium metatungstate concentration is 5-15 wt%. The acid is selected from one or more combinations of concentrated nitric acid, concentrated sulfuric acid, concentrated hydrochloric acid, and concentrated phosphoric acid. The mass of the initiator is 0.2%-5% of the total solid mass, and the total solid mass is the solid mass of the molecular sieve, matrix, and lubricant.

2. The method for preparing the Beta molecular sieve catalyst according to claim 1, characterized in that, In step a1, the molar ratio of K2O to Na2O in the alkaline solution is (0.1~0.5):1; And / or, in step a1, the concentration of (Na2O+K2O) in the alkaline solution is 20~50wt%.

3. The method for preparing the Beta molecular sieve catalyst according to claim 1, characterized in that, Step b includes the following steps: After exchanging ammonium ions 1 to 3 times in an ammonium salt aqueous solution, the Na-type Beta molecular sieve is washed, dried, and calcined to obtain the H-type Beta molecular sieve.

4. The method for preparing the Beta molecular sieve catalyst according to claim 3, characterized in that, During the ammonium ion exchange process in step b, the reaction system temperature is 30–110℃; And / or, during the drying process in step b, the drying temperature is 100–140°C and the drying time is 2–5 hours; And / or, during the roasting process in step b, the roasting temperature is 450–550℃ and the roasting time is 3–6 hours.

5. The method for preparing the Beta molecular sieve catalyst according to claim 1, characterized in that, Step c includes the following steps: After the matrix is ​​added to the H-type Beta molecular sieve and mixed evenly, the initiator is added and stirred evenly, and then an aqueous solution of lubricant is added and stirred evenly. The mixture is then kneaded, extruded, dried, and calcined to obtain the Beta molecular sieve catalyst.

6. The method for preparing the Beta molecular sieve catalyst according to claim 5, characterized in that, In step c: the solid weight ratio of H-type Beta molecular sieve, matrix, and lubricant is (30~60):(50~35):(20~5); And / or, during the drying process in step c, the drying temperature is 100–140°C and the drying time is 2–5 hours; And / or, during the roasting process in step c, the roasting temperature is 500–650℃ and the roasting time is 3–6 hours.

7. The method for preparing the Beta molecular sieve catalyst according to claim 5, characterized in that, The concentration of the aqueous solution of the lubricant is 10~30wt%.

8. The method for preparing the Beta molecular sieve catalyst according to claim 1, characterized in that, The alkaline source is sodium hydroxide; And / or, the potassium source is selected from one or a combination of potassium hydroxide, potassium peroxide, potassium carbonate, potassium bicarbonate, and potassium chloride; And / or, the silicon source is selected from one or a combination of several of the following: silica, tetraethyl orthosilicate, water glass, and silica sol; And / or, the organic template agent is one of tetraethylammonium hydroxide, tetraethylammonium chloride, and tetraethylammonium bromide; And / or, the ammonium salt aqueous solution is one of 0.5~5 mol / L ammonium nitrate aqueous solution, ammonium sulfate aqueous solution, ammonium chloride aqueous solution, and ammonium bicarbonate aqueous solution; And / or, the matrix is ​​selected from one or a combination of several of the following: kaolin, attapulgite, diatomite, and boehmite; And / or, the lubricant is guar gum powder and / or methylcellulose.

9. The Beta molecular sieve catalyst obtained by the preparation method of the Beta molecular sieve catalyst according to any one of claims 1 to 8.

10. The application of the Beta molecular sieve catalyst obtained by the preparation method according to any one of claims 1 to 8, or the Beta molecular sieve catalyst according to claim 9, in the high-space-velocity liquid-phase alkylation reaction of benzene and ethylene to prepare ethylbenzene, characterized in that, The evaluation conditions were: fixed-bed reactor, 10 mL loading, reaction temperature 250℃, reaction pressure 3.5 MPa, benzene / ethylene molar ratio 4, and benzene volume hourly space velocity 8 h⁻¹. -1 .

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