How is ZSM-5 molecular sieve made?
ZSM-5 molecular sieve is a crystalline material with unique microporous structure, which is widely used in the fields of catalyst, adsorbent and ion exchanger because of its high activity and selectivity. Its production process mainly includes synthesis, separation, purification and activation steps.
1. Synthesis: The synthesis of ZSM-5 molecular sieve usually adopts hydrothermal synthesis method, taking sodium silicate, sodium aluminate, sodium hydroxide and other raw materials, heated to a certain temperature and pressure in a high-pressure reactor, and crystals are formed after a certain time of reaction. The key parameters of synthesis include reaction temperature, pressure, raw material concentration and reaction time, etc. These parameters will directly affect the structure and performance of molecular sieves.
2. Separation: The product after synthesis needs to be separated to extract the molecular sieve crystals. Commonly used separation methods include centrifugation, filtration and sedimentation. These methods can separate molecular sieve crystals from the reaction solution for further processing.
3. Purification: In order to remove the impurities in the molecular sieves, purification is required. Purification methods include acid washing, water washing, ion exchange and so on. These methods can remove the impurities in the molecular sieve and improve its purity and performance.
4. Activation: activation is one of the important steps in the production of molecular sieves, which can improve the activity and selectivity of molecular sieves. Activation methods include heat treatment, chemical treatment and physical treatment. Heat treatment is the most commonly used activation method, which can eliminate defects and impurities in the molecular sieve by increasing the temperature and improve its performance.