Solvent-free solid-phase synthesis method of silicon-aluminum molecular sieve ZSM-5

Abstract

The invention discloses a silicon-aluminum molecular sieve ZSM-5 solvent-free solid-phase synthesis method, the molecular sieve solid-phase solvent-free synthesis refers to that no solvent is used or the use of the solvent is greatly reduced in a molecular sieve synthesis process, and a molecular sieve synthesis system is mainly a solid phase. In the solvent-free synthesis process of the silicon-aluminum molecular sieve ZSM-5, a grinding material exerts a mechanical force effect on raw materials such as a silicon source, an aluminum source and a template agent for synthesizing the molecular sieve. Different from a traditional rotary or stirring hydrothermal reaction kettle, the molecular sieve nucleation and crystallization growth process can be promoted by introducing mechanical force in the process. Meanwhile, the solvent-free solid-phase synthesis system can effectively reduce the use of a template agent and a solvent, reduces the generation of wastes and reduces the energy consumption of chemical synthesis, and is lower in equipment cost and easy to operate.

Description

Technical Field

[0001] The present application relates to a method for solvent-free solid phase synthesis of a silicon-alumina molecular sieve ZSM-5, and belongs to the field of chemistry and chemical engineering. Background Art

[0002] ZSM-5 zeolite is a zeolite molecular sieve synthesized by Mobil Corporation of the United States in the late 1960s using organic amine cations as templates. It has many unique features in chemical composition, crystal structure and physicochemical properties. The structural feature is that it is a crystalline aluminosilicate with a combination of ten-membered channels in both directions. Its basic structural unit is composed of eight five-membered rings, with no cage-like cavities, only channels. ZSM-5 has two sets of intersecting channels, one is straight through, and the other is zigzag and perpendicular to each other. The channel is elliptical, and its window diameter is 0.55-0.60nm. This type of molecular sieve has a selective effect on reactants and products because its reaction space and inlet and outlet shapes are similar. In addition, its structural uniformity and hydrothermal stability make it a good selective catalyst raw material.

[0003] ZSM-5 molecular sieve has been widely used in China. It is mainly used in diesel hydrodecondensation catalyst, fixed bed catalytic cracking catalyst and fluidized bed catalytic cracking reaction. Adding ZSM-5 molecular sieve to FCC catalyst can greatly improve the octane number of gasoline and increase the olefin content of gas. ZSM-5 molecular sieve added to FCC catalyst at home and abroad is the most used one among ZSM-5 molecular sieves, mainly focusing on SiO2 / Al2O3 (silicon aluminum molar ratio). FCC additives are widely used in my country to reduce olefins in gasoline. In this regard, the ratio of SiO2 / Al2O3 is between 38 and 40. In addition, molecular sieves with a SiO2 / Al2O3 ratio of 25-30 are used for residual oil catalytic cracking at home and abroad. In addition, ZSM-5 molecular sieve is also widely used in shape-selective catalysis in the chemical industry, such as diethylbenzene catalyst and xylene isomerization catalyst.

[0004] Traditional molecular sieve synthesis mainly uses a hydrothermal synthesis system, using an intermittent hydrothermal reaction synthesis kettle as a reaction vessel, which has low efficiency, large heat loss, and high energy consumption. At the same time, intermittent hydrothermal reaction synthesis kettles are usually synthesized using a stirring system, so there are many restrictions on the selection of synthesis formulas. The feed liquid needs to have good fluidity. If the feed liquid is a slurry with high viscosity or even a solid state, it is difficult to synthesize. Therefore, more solvents and organic base templates are usually used, resulting in high synthesis costs and subsequent sewage treatment costs. At the same time, the synthesis speed of traditional molecular sieve hydrothermal synthesis kettles is slow and the synthesis efficiency is low. The product particle size distribution of traditional molecular sieve hydrothermal synthesis kettles is uneven, and there is a problem of large or small particle size. Therefore, the development of the molecular sieve synthesis industry is limited. At present, there is solid-phase molecular sieve synthesis work carried out on a laboratory scale, but the scale is small. At the same time, the biggest problem in the amplification of solid-phase synthesis is the influence of heat transfer and mass transfer in the reaction system. Summary of the invention

[0005] According to one aspect of the present application, a method for solvent-free solid phase synthesis of silicon-aluminum molecular sieve ZSM-5 is provided, which method does not require a large amount of solvent used in the traditional synthesis process and has a high degree of automation. In this method, mechanical force is used to assist the synthesis of molecular sieves, which is a new technology that uses mechanical force to assist molecules to self-assemble in solution to form crystals. This method can prepare high-quality, high-crystallization, and high-specific surface area molecular sieve materials in a relatively short period of time. The traditional synthesis method is to use a large amount of solvent to synthesize under hydrothermal conditions, which consumes a lot of solvent and template agent, and the subsequent treatment and discharge of wastewater will greatly increase the cost of synthesis. The process of solvent-free solid phase synthesis does not require a large amount of solvent, and the reaction material is solid. Compared with the traditional synthesis method, the molecular sieve crystals prepared by the mechanical force-assisted synthesis method are more uniform, complete, and defect-free, and the crystals have a higher degree of crystallinity. The advantages of mechanical force-assisted synthesis of molecular sieves are that they can shorten the preparation time, improve product quality, and reduce chemical waste. The equipment cost is low and easy to operate. Mechanical force-assisted synthesis of molecular sieves has the advantages of short preparation time, high crystal quality, large specific surface area, reduced waste and wider applicability. It will become an important development direction of molecular sieve preparation technology in the future.

[0006] This application adopts the following technical solutions:

[0007] A method for solvent-free solid phase synthesis of a silicon-alumina molecular sieve ZSM-5 comprises the following steps:

[0008] A mixture containing an aluminum source, a silicon source, an organic base template and a grinding material is placed in a closed container and continuously rotated for solid phase crystallization to obtain the silicon-aluminum molecular sieve ZSM-5.

[0009] The organic base template agent includes at least one of a quaternary ammonium salt and a quaternary ammonium base.

[0010] The grinding material provides additional mechanical force to the molecular sieve raw materials during the synthesis process

[0011] Optionally, the molar ratio of the aluminum source, the silicon source, and the organic base template is (0.005-0.1):1:(0.01-10);

[0012] Wherein, the molar number of the aluminum source is AlO 3 / 2 The number of moles;

[0013] The mole number of the silicon source is calculated as the mole number of SiO2;

[0014] The molar number of the organic base template agent is calculated based on the molar number of N atoms in the organic base template agent.

[0015] Optionally, the rotation speed is 1 rpm to 80 rpm.

[0016] Optionally, the rotation speed during the molecular sieve synthesis process is selected from any value of 1 rpm, 5 rpm, 10 rpm, 20 rpm, 30 rpm, 40 rpm, 50 rpm, 60 rpm, 70 rpm, 75 rpm, 80 rpm, or any range therebetween.

[0017] Optionally, the conditions for the solid phase crystallization are: a crystallization temperature of 100 to 200° C., and a crystallization time of less than or equal to 168 h.

[0018] Optionally, the conditions for the solid phase crystallization are: a crystallization temperature of 100 to 130° C., and a crystallization time of 1 to 6 hours.

[0019] Optionally, the method for solvent-free solid phase synthesis of the silica-alumina molecular sieve ZSM-5 is:

[0020] A mixture consisting of an aluminum source, a silicon source, an organic base template, and a grinding material is placed in a closed container, and is continuously rotated for solid phase crystallization to obtain the silicon-aluminum molecular sieve ZSM-5.

[0021] Optionally, the closed container is a rotary reactor device.

[0022] In the present application, the rotary reactor device is used as a mechanically assisted rotary reaction device.

[0023] The steps of the method for synthesizing silicon aluminum molecular sieve ZSM-5 using a rotary reactor device are as follows:

[0024] Aluminum source, silicon source and organic base template are added into the rotating reactor through the feed port, and grinding material is added into the reactor. After sealing, the temperature is increased and the reactor is rotated by a motor. The grinding material continuously applies mechanical force to the synthetic raw materials during the rotation process. After the reaction is completed, the molecular sieve product is poured out through the discharge port.

[0025] Optionally, the organic base template is selected from at least one of tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, triethylpropylammonium hydroxide, tetrapropylammonium halide, tetraethylammonium halide, tetrabutylammonium halide and triethylpropylammonium halide.

[0026] Optionally, the molar ratio of the aluminum source, the silicon source, and the organic base template is (0.01-0.08):1:(0.05-5).

[0027] Optionally, the molar ratio of the aluminum source to the silicon source is selected from any value of 0.005:1, 0.008:1, 0.01:1, 0.02:1, 0.03:1, 0.04:1, 0.05:1, 0.06:1, 0.07:1, 0.08:1, 0.09:1, 0.1:1, or any range between the two, wherein the molar number of the aluminum source is expressed as AlO 3 / The molar number of the silicon source is measured in terms of the molar number of SiO2.

[0028] Optionally, the molar ratio of the silicon source and the organic base template is selected from any value of 1:0.01, 1:0.02, 1:0.05, 1:0.1, 1:0.2, 1:0.3, 1:0.4, 1:0.5, 1:1, 1:2, 1:3, 1:4, 1:5, 1:8, 1:10, or any range between two values, wherein the molar number of the template is calculated based on the molar number of N atoms in the template; the molar number of the silicon source is calculated based on the molar number of SiO2.

[0029] Optionally, the organic base template further comprises at least one of aliphatic amine and alcohol amine compounds;

[0030] Preferably, the fatty amine is selected from at least one of ethylamine, diethylamine, triethylamine, n-butylamine, butanediamine, hexamethylenediamine and octanediamine;

[0031] The alcoholamine is selected from at least one of monoethanolamine, diethanolamine and triethanolamine.

[0032] Optionally, the material of the grinding material is selected from at least one of agate, aluminum oxide, zirconium oxide, stainless steel, and synthetic resin.

[0033] Optionally, the grinding material has a shape selected from at least one of a sphere, a rod, a cube, a triangular pyramid, and a star.

[0034] Optionally, the aluminum source is selected from at least one of sodium aluminate, aluminum sulfate, boehmite, metallic aluminum, aluminum nitrate, aluminum isopropoxide, and aluminum hydroxide.

[0035] The silicon source is selected from at least one of silica sol, ethyl orthosilicate, methyl orthosilicate and white carbon black.

[0036] The method for synthesizing the silica-alumina molecular sieve ZSM-5 proposed in this application can shorten the preparation time, improve product quality and reduce chemical waste, etc. It can effectively reduce the amount of template and solvent used in the traditional hydrothermal synthesis process, and is particularly suitable for the synthesis process in which the system is a solid phase.

[0037] Optionally, the solid phase crystallization temperature is selected from any value of 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, 160°C, 170°C, 180°C, 190°C, 200°C, or any range therebetween.

[0038] Optionally, the solid phase crystallization time is selected from any value of 1h, 6h, 12h, 24h, 48h, 72h, 96h, 120h, 144h, 168h, or any range therebetween.

[0039] The technical solution of the present application is a solvent-free solid phase synthesis method of a silicon-aluminum molecular sieve ZSM-5, wherein the molecular sieve solid phase solvent-free synthesis refers to not using a solvent or greatly reducing the use of a solvent in the process of synthesizing a molecular sieve, and the molecular sieve synthesis system is mainly solid phase. In the process of solvent-free synthesis of silicon-aluminum molecular sieve ZSM-5, the grinding material exerts mechanical force on raw materials such as silicon source, aluminum source and template agent for synthesizing the molecular sieve. Different from the traditional rotating or stirred hydrothermal reactor, the introduction of mechanical force in this process can promote the nucleation and crystal growth process of the molecular sieve. At the same time, the solvent-free solid phase synthesis system can effectively reduce the use of template agents and solvents, reduce the generation of waste and reduce the energy consumption of chemical synthesis, and the equipment cost is low and easy to operate.

[0040] The beneficial effects of this application include:

[0041] 1) The method of the present application is to synthesize the silicon-alumina molecular sieve ZSM-5 under solvent-free solid phase conditions by mechanical force assistance. This method can prepare the molecular sieve material in a relatively short time; the method and equipment are simple, the degree of automation is high, and it is particularly suitable for the synthesis process in which the molecular sieve synthesis system is a solid phase, the equipment cost is low, and it is easy to operate;

[0042] 2) The method for solvent-free solid phase synthesis of silicon-aluminum molecular sieve ZSM-5 in this application can be synthesized using a solid phase synthesis system. The advantage of solid phase synthesis is that the autogenous pressure of the reaction system is low, the pressure resistance requirement of the equipment is low, and the equipment cost is greatly reduced; at the same time, the solid phase system can reduce the template agent. No solvent is required, the discharge of chemical wastewater and waste is effectively reduced, environmental pollution is reduced, it meets the requirements of atomic economy and green chemistry, and is more suitable for the development of modern chemical industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 This is a scanning electron microscope image of the product synthesized in Example 1 of this application.

[0044] Figure 2 This is the X-ray powder diffraction image of the product synthesized in Example 1 of the present application.

[0045] Figure 3 This is a scanning electron microscope image of the product synthesized in Example 2 of this application.

[0046] Figure 4 This is the X-ray powder diffraction image of the product synthesized in Example 2 of this application. DETAILED DESCRIPTION

[0047] The present application is described in detail below with reference to embodiments, but the present application is not limited to these embodiments.

[0048] Unless otherwise specified, the raw materials in the examples of this application were purchased through commercial channels.

[0049] The analysis method in the examples of this application is as follows:

[0050] In the examples of the present application, the SEM morphology analysis of the product was performed using a Hitachi SU8020 scanning electron microscope.

[0051] In the examples of the present application, the X-ray powder diffraction phase analysis (XRD) of the product was performed using an X'Pert PRO X-ray diffractometer from PANalytical of the Netherlands, with a Cu target, a Kα radiation source (λ=0.15418 nm), a voltage of 40 KV, and a current of 40 mA.

[0052] According to one embodiment of the present application, a method for mechanical solvent-free solid phase synthesis of silicon-aluminum molecular sieve ZSM-5 is operated, characterized in that the method comprises the following steps:

[0053] The raw materials of the molecular sieve to be synthesized: aluminum source, organic base template, silicon source, etc. are mixed in a certain proportion to obtain a solid phase mixture, and the solid phase mixture has the following molar ratio:

[0054] AlO 3 / 2 :SiO2=0.005~0.1:1;

[0055] Organic base template: SiO2 = 0.01 ~ 10: 1;

[0056] The silicon content in the silicon source is calculated as the number of moles of SiO2, and the aluminum content in the aluminum source is calculated as the number of moles of AlO 3 / 2 The content of the organic base template is calculated based on the molar number of N atoms.

[0057] The solid phase mixture is added to a rotating reactor, and grinding materials are added to the reactor. The materials of the grinding materials include one or more mixtures of materials such as agate, aluminum oxide, zirconium oxide, stainless steel or synthetic resin. The shapes of the grinding materials include one or more mixtures of different shapes such as spheres, rods, cubes, triangular pyramids or stars. After sealing, the temperature is increased and rotated. During the reaction, the speed is between 1rpm and 80rpm, the temperature of the rotating reactor is between 100℃ and 200℃, and the molecular sieve synthesis time crystallization does not exceed 7 days. The grinding material continuously applies mechanical force to the synthetic raw materials during the rotation process, and the molecular sieve product is poured out through the discharge port after the reaction is completed.

[0058] Example 1

[0059] 60 g of tetraethyl orthosilicate, 5 g of aluminum isopropoxide, and 15 g of tetrapropylammonium hydroxide were placed in a molecular sieve synthesis container; agate grinding beads were added to the reaction system, and the reaction was carried out at a temperature of 170° C., a rotation speed of 40 rpm, and a reaction time of 1 day to synthesize a ZSM-5 molecular sieve product.

[0060] Example 2

[0061] 30 g of silica sol, 5 g of boehmite, and 15 g of tetrabutylammonium hydroxide were placed in a molecular sieve synthesis container, and zirconium oxide and aluminum oxide grinding rods were added to the reaction system. The ZSM-5 molecular sieve product was synthesized at a temperature of 120° C., a rotation speed of 70 rpm, and a reaction time of 6 hours.

[0062] Example 3

[0063] 60g of fumed silica, 3g of sodium aluminate and 25g of octanediamine were placed in a molecular sieve synthesis container; stainless steel ground triangular pyramids were added to the reaction system, and the ZSM-5 molecular sieve product was synthesized at a temperature of 200°C, a rotation speed of 20rpm and a reaction time of 72 hours.

[0064] Embodiments 4 to 13

[0065] The specific ingredient types, materials and synthesis conditions are shown in Table 1 below. The synthesis equipment and other operations during the synthesis process are the same as those in Example 1.

[0066] Table 1 Molecular sieve synthesis conditions of Examples 4-13

[0067]

[0068] The above are only a few embodiments of the present application and do not constitute any form of limitation to the present application. Although the present application is disclosed as above with preferred embodiments, it is not intended to limit the present application. Any technician familiar with the profession, without departing from the scope of the technical solution of the present application, using the technical content disclosed above to make slight changes or modifications are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A method for solvent-free solid phase synthesis of silicon-alumina molecular sieve ZSM-5, characterized in that: The steps include: Placing a mixture containing an aluminum source, a silicon source, an organic base template, and a grinding material in a closed container, rotating it continuously, and performing solid phase crystallization to obtain the silicon-aluminum molecular sieve ZSM-5; The organic base template agent includes at least one of a quaternary ammonium salt and a quaternary ammonium base.

2. The method according to claim 1, characterized in that The molar ratio of the aluminum source, the silicon source, and the organic base template agent is (0.005-0.1):1:(0.01-10); Wherein, the molar number of the aluminum source is AlO 3 / 2 The number of moles; The mole number of the silicon source is calculated as the mole number of SiO2; The molar number of the organic base template agent is calculated based on the molar number of N atoms in the organic base template agent.

3. The method according to claim 1, characterized in that The rotation speed is 1 rpm to 80 rpm.

4. The method according to claim 1, characterized in that The conditions for the solid phase crystallization are: a crystallization temperature of 100 to 200° C. and a crystallization time of less than or equal to 168 hours; Preferably, the conditions for the solid phase crystallization are: a crystallization temperature of 100 to 130° C., and a crystallization time of 1 to 6 hours.

5. The method according to claim 1, characterized in that The method for solvent-free solid phase synthesis of the silicon-aluminum molecular sieve ZSM-5 is: A mixture consisting of an aluminum source, a silicon source, an organic base template, and a grinding material is placed in a closed container, and is continuously rotated for solid phase crystallization to obtain the silicon-aluminum molecular sieve ZSM-5.

6. The method according to claim 1, characterized in that The organic base template agent is selected from at least one of tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, triethylpropylammonium hydroxide, tetrapropylammonium halide, tetraethylammonium halide, tetrabutylammonium halide and triethylpropylammonium halide.

7. The method according to claim 1, characterized in that The molar ratio of the aluminum source, the silicon source and the organic base template agent is (0.01-0.08):1:(0.05-5).

8. The method according to claim 1, characterized in that The organic base template agent also includes at least one of aliphatic amine and alcohol amine compounds; Preferably, the fatty amine is selected from at least one of ethylamine, diethylamine, triethylamine, n-butylamine, butanediamine, hexamethylenediamine and octanediamine; The alcoholamine is selected from at least one of monoethanolamine, diethanolamine and triethanolamine.

9. The method according to claim 1, characterized in that: The material of the grinding material is selected from at least one of agate, aluminum oxide, zirconium oxide, stainless steel, and synthetic resin; Preferably, the shape of the grinding material is selected from at least one of sphere, rod, cube, triangular pyramid and star.

10. The method according to claim 1, characterized in that The aluminum source is selected from at least one of sodium aluminate, aluminum sulfate, boehmite, metallic aluminum, aluminum nitrate, aluminum isopropoxide, and aluminum hydroxide; The silicon source is selected from at least one of silica sol, ethyl orthosilicate, methyl orthosilicate and white carbon black.

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