Method for solvent-free solid-phase synthesis of LTA type molecular sieve

Abstract

The invention discloses a solvent-free solid-phase synthesis method of an LTA type molecular sieve, the solvent-free synthesis of the molecular sieve refers to that no solvent is used or the use of the solvent is greatly reduced in the synthesis process of the molecular sieve, and the molecular sieve synthesis system is mainly a solid phase. In the solvent-free synthesis process of the LTA type molecular sieve, a grinding material exerts a mechanical force effect on raw materials such as a silicon source, an aluminum source and an alkali source 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 LTA type molecular sieves, belonging to the field of chemistry and chemical engineering. Background Art

[0002] LTA molecular sieve is a porous ceramic material with a specific pore size and structure. Its crystal structure is orthorhombic and belongs to one of the zeolite molecular sieves. Due to its small pore size and polar affinity, LTA molecular sieve is widely used in various catalytic, adsorption and separation processes. LTA molecular sieve can be used for gas and liquid separation, such as separation of carbon dioxide and carbon monoxide mixture, separation of hydrocarbons in petroleum, etc. In addition, LTA molecular sieve can also be used for the controlled release of drugs, enzymes and other chemicals in water. LTA molecular sieve can be used as a catalyst carrier and is widely used in chemical reactions and industrial processes, such as the methylation reaction of phthalic anhydride and methanol, ethylene oxidation reaction, and for the dehydration of formaldehyde and ethanol to produce ethylene. LTA molecular sieve can be used as an efficient desiccant to absorb moisture in the container, such as in gas packaging to maintain the freshness and quality of the product.

[0003] Industrial synthesis of LTA molecular sieves requires high-cost raw materials, relatively high temperature and pressure, and complex post-processing procedures, all of which lead to high production costs, thus limiting its industrial application. The preparation of LTA molecular sieves also requires the use of a large amount of water, and the discharge of wastewater has become an increasingly serious environmental problem, causing a great impact on the environment.

[0004] At the same time, the industrial production process of molecular sieves in the prior art is usually carried out using an intermittent hydrothermal reaction synthesis kettle, which has many restrictions on the selection of raw materials and preparation conditions, and has low efficiency, high energy consumption, and high environmental protection treatment costs for subsequent waste liquids. Therefore, a new, efficient and environmentally friendly molecular sieve synthesis process is urgently needed. In the prior art process, the use of raw materials is usually carried out in a liquid phase reaction, and the viscosity requirements of the feed liquid cannot be too high. Summary of the invention

[0005] According to one aspect of the present application, a method for solvent-free solid-phase synthesis of LTA-type molecular sieves is provided, which uses an inorganic base source and combines the mechanical force of abrasive materials to assist crystallization, thereby overcoming the problem of large-scale use of solvents and templates in the hydrothermal reaction method in the prior art, avoiding the use of solvents and organic templates, and further solving the problem of environmental protection treatment of subsequent wastewater from hydrothermal reactions in the prior art. At the same time, the new solid-phase synthesis process of the present application is used to simply and quickly prepare more uniform, complete, defect-free, and more crystalline molecular sieve materials, and also solves the problem of long time-consuming industrial production preparation process of molecular sieve hydrothermal reactions in the prior art.

[0006] This application adopts the following technical solutions:

[0007] A method for solvent-free solid phase synthesis of LTA type molecular sieves comprises the following steps:

[0008] Placing a mixture containing an aluminum source, a silicon source, an alkali source, and a grinding material in a closed container, rotating it continuously, and performing solid phase crystallization to obtain the LTA type molecular sieve;

[0009] The alkali source is selected from at least one of NaOH and KOH.

[0010] The grinding material provides additional mechanical force for the molecular sieve raw material during the synthesis process. Optionally, the molar ratio of the aluminum source, silicon source, and alkali source is (0.005-0.1):1:(0.01-10);

[0011] Wherein, the molar number of the aluminum source is AlO 3 / 2 The number of moles;

[0012] The mole number of the silicon source is calculated as the mole number of SiO2;

[0013] The molar number of the alkali source is based on the OH -1 The number of moles;

[0014] Optionally, the molar ratio of the aluminum source, silicon source and alkali source is (0.01-0.08):1:(0.05-5).

[0015] 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 / 2 The molar number of the silicon source is measured in terms of the molar number of SiO2.

[0016] Optionally, the molar ratio of the silicon source to the alkali source 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 the two, wherein the molar number of the alkali source is based on the OH in the alkali source. -1 The molar number of the silicon source is measured in terms of the molar number of SiO2.

[0017] Optionally, the rotation speed is 1 rpm to 80 rpm.

[0018] 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.

[0019] Optionally, the conditions for the solid phase crystallization are: a crystallization temperature of 60 to 120° C., and a crystallization time of less than or equal to 168 h.

[0020] Optionally, the material of the grinding material is selected from at least one of agate, aluminum oxide, zirconium oxide, stainless steel, and synthetic resin.

[0021] 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.

[0022] 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.

[0023] The silicon source is selected from at least one of silica sol, ethyl orthosilicate, methyl orthosilicate and white carbon black.

[0024] Optionally, the conditions for the solid phase crystallization are: a crystallization temperature of 100 to 120° C., and a crystallization time of 1 to 6 hours.

[0025] The method for synthesizing the LTA type molecular sieve 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.

[0026] Optionally, the solid phase crystallization temperature is selected from any value of 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, or any range therebetween.

[0027] 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.

[0028] Optionally, the method for solvent-free solid phase synthesis of LTA type molecular sieve is:

[0029] A mixture consisting of an aluminum source, a silicon source, an alkali source and a grinding material is placed in a closed container and continuously rotated for solid phase crystallization to obtain the LTA type molecular sieve.

[0030] Optionally, the closed container is a rotary reactor device.

[0031] In the present application, the rotary reactor device is used as a mechanically assisted rotary reaction device.

[0032] The steps of the method for synthesizing LTA type molecular sieve using a rotary reactor device are as follows:

[0033] Aluminum source, silicon source and alkali source are added into the rotating reactor through the feed port, grinding material is added into the reactor, the temperature is raised after sealing, and the motor is used to drive the rotating reactor to rotate. 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.

[0034] The technical solution of the present application is a method for solvent-free solid-phase synthesis of LTA type molecular sieves. During the reaction process, the reaction system is all solid phase. Therefore, combined with the specific rotation speed of the reactor, the grinding material exerts mechanical force on solid-phase raw materials such as silicon source and aluminum source, which can promote the nucleation and crystal growth of the molecular sieve. The technical solution of the present application can effectively avoid the use of organic templates and solvents, and reduce production energy consumption and production time.

[0035] The beneficial effects of the present invention include: Solvent-free solid phase synthesis method of LTA type molecular sieve

[0036] 1) The method of the present application uses a solid phase synthesis system to synthesize LTA type molecular sieves under solvent-free solid phase conditions, which can obtain a shorter molecular sieve material production cycle. At the same time, because of the all-solid phase production embodiment, the use of organic templates and solvents can be avoided, and the production wastewater treatment problems existing in the prior art are avoided. Overall, compared with the current hydrothermal system production, the cost of raw materials and processes in the application technical solution can be effectively reduced, and the autogenous pressure of solid phase synthesis is low, so the investment cost of equipment will also be significantly reduced, which will contribute to the economical and green industrial development of LTA type molecular sieve preparation. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 This is a scanning electron microscope image of the product synthesized in Example 1 of this application.

[0038] Figure 2 This is the X-ray powder diffraction image of the product synthesized in Example 1 of the present application.

[0039] Figure 3 This is a scanning electron microscope image of the product synthesized in Example 2 of this application.

[0040] Figure 4 This is the X-ray powder diffraction image of the product synthesized in Example 2 of this application. DETAILED DESCRIPTION

[0041] The present application is described in detail below with reference to embodiments, but the present application is not limited to these embodiments.

[0042] Unless otherwise specified, the raw materials in the examples of this application were purchased through commercial channels.

[0043] The analysis method in the examples of this application is as follows:

[0044] In the examples of the present application, the SEM morphology analysis of the product was performed using a Hitachi SU8020 scanning electron microscope.

[0045] 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.

[0046] According to one embodiment of the present application, a method for mechanical solvent-free solid phase synthesis of LTA molecular sieves is operated, characterized in that the method comprises the following steps:

[0047] The raw materials for synthesizing the molecular sieve: silicon source, alkali source, silicon source, etc. are mixed in a certain proportion to obtain a solid phase mixture. Preferably, the solid phase mixture has the following molar ratio:

[0048] AlO 3 / 2 :SiO2=0.005~0.1:1;

[0049] Alkali source: SiO2 = 0.01 ~ 10: 1;

[0050] The silicon content in the silicon source is calculated as the number of moles of SiO2, and the content of the aluminum source is calculated as the number of moles of AlO 3 / 2 The content of alkali source is calculated by the molar number of OH -1 The number of moles.

[0051] 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. The speed during the reaction is between 1rpm and 80rpm, the temperature of the rotating reactor is between 60℃ and 120℃, 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.

[0052] Example 1

[0053] In this embodiment, 25 g of white carbon black, 5 g of aluminum isopropoxide, and 4 g of sodium hydroxide were placed in a molecular sieve synthesis container; agate grinding beads were added to the reaction system, and the reaction time was 1 day at a temperature of 120° C. and a rotation speed of 40 rpm to synthesize the LTA molecular sieve product.

[0054] Example 2

[0055] 30g of silica sol, 5g of boehmite and 15g of sodium hydroxide were placed in a molecular sieve synthesis container, zirconium oxide and aluminum oxide grinding rods were added to the reaction system, and the LTA molecular sieve product was synthesized at a temperature of 80°C, a reaction time of 6 hours and a rotation speed of 70rpm.

[0056] Example 3

[0057] 60g of fumed silica, 3g of sodium aluminate and 25g of sodium hydroxide were placed in a molecular sieve synthesis container; stainless steel ground triangular pyramids were added to the reaction system, and the reaction time was 72 hours at a temperature of 100°C and a rotation speed of 20rpm to synthesize the LTA molecular sieve product.

[0058] Embodiments 4 to 13

[0059] 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.

[0060] Table 1 Molecular sieve synthesis conditions of Examples 4-13

[0061]

[0062] 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 LTA type molecular sieves, characterized in that: The steps include: Placing a mixture containing an aluminum source, a silicon source, an alkali source, and a grinding material in a closed container, rotating it continuously, and performing solid phase crystallization to obtain the LTA type molecular sieve; The alkali source is selected from at least one of NaOH and KOH.

2. The method according to claim 1, characterized in that The molar ratio of the aluminum source, silicon source and alkali source 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 alkali source is based on the OH -1 The number of moles; Preferably, the molar ratio of the aluminum source, silicon source and alkali source is (0.01-0.08):1:(0.05-5).

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 60 to 120° C., and a crystallization time of less than or equal to 168 hours.

5. 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.

6. The method according to claim 1, characterized in that The shape of the grinding material is selected from at least one of sphere, rod, cube, triangular pyramid and star.

7. 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.

8. The method according to claim 1, characterized in that The silicon source is selected from at least one of silica sol, ethyl orthosilicate, methyl orthosilicate and white carbon black.

9. The method according to claim 1, characterized in that: The conditions for the solid phase crystallization are: a crystallization temperature of 100 to 120° C. and a crystallization time of 1 to 6 hours.

10. The method according to claim 1, characterized in that The method is: A mixture consisting of an aluminum source, a silicon source, an alkali source and a grinding material is placed in a closed container and continuously rotated for solid phase crystallization to obtain the LTA type molecular sieve.

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