Synthesis Method of Microporous Molecular Sieve

Traditional microporous molecular sieve synthesis methods include: hydrothermal system synthesis method, non-aqueous system synthesis method, vapor phase system synthesis method, dry powder system synthesis method, microwave method, high temperature roasting method, guide agent method and so on.

1. Hydrothermal system synthesis method

Also known as hydrothermal crystallization, zeolite crystals are prepared by combining silicon source, aluminum source, alkali (organic alkali and inorganic alkali) and water in a certain proportion, putting them into a reaction kettle, and crystallizing at a certain temperature. Generally, low-silicon-aluminum ratio zeolites are synthesized in low-temperature hydrothermal systems, while high-silicon-aluminum ratio zeolites are synthesized in high-temperature hydrothermal systems.

2. Non-aqueous system synthesis method

The non-aqueous system synthesis method was pioneered by Bibbq and Dale in the early 1980s. It does not use water as solvent, but instead uses organic matter as solvent to synthesize zeolite. It opens up a new way of zeolite synthesis and provides strong evidence for the solid phase transformation mechanism of zeolite.

3. Vapor Phase System Synthesis Method

The vapor phase system synthesis method is different from the hydrothermal system synthesis method and the non-aqueous system synthesis method. The vapor phase system synthesis method is to place the silicon source aluminum source and the inorganic base in the vapor phase of the solvent and the organic template agent for zeolite synthesis, thereby developing A new synthesis method is provided, which reduces the amount of organic amine in synthesis, reduces environmental pollution and improves synthesis efficiency.

4. Synthesis of dry powder system

Dry powder system synthesis method is a new method for synthesizing zeolite proposed in recent years. It is characterized in that the reaction material is in the form of dry powder, the template agent acts on the synthesis system in the form of adsorption, and no liquid appears in the whole crystallization process. This method also provides a good explanation for the solid-phase catalytic mechanism.

5. Microwave method

Since microwave technology has been widely used in the field of chemical synthesis. In recent years, microwave synthesis technology has been extended to the synthesis of molecular sieves. Thus opening up a new route for the synthesis of molecular sieves. Y-type zeolite and ZSM-5 molecular sieve were prepared by microwave method.

6. High temperature roasting method

The reaction mixture is directly calcined at high temperature to obtain AlPO4-5 molecular sieve product. This new synthetic route has the advantages of simple equipment (no need to use high pressure reactor), short production cycle and high unit yield.

7. Directing agent method

A large amount of expensive organic template agent TEAOH must be added to the synthesis system of zeolite beta, resulting in high synthesis cost. Using the directing agent method to synthesize zeolite beta, it only needs to add a small amount of zeolite beta directing agent (without adding an organic template agent) to synthesize zeolite beta, and can synthesize zeolite molecular sieves with a low silicon-aluminum ratio, which greatly reduces the amount of organic compounds in the synthesis system. The dosage of the template agent reduces the synthesis cost and reduces the pollution to the environment.

8. Other synthesis methods include: gel method, double silicon source method, and pure solid ingredient synthesis method.