When 4a molecular sieve is not packed tightly or the storage environment is damaged, how to deal with its water absorption and moisture? Today we will detail the adsorption capacity of molecular sieve and the treatment methods of water absorption and hygroscopicity.
Molecular sieve has a strong adsorption capacity. It can not only absorb water, but also absorb impurities in the air. Therefore, in industrial production, it is often used for adsorption operations, thus playing a good role in separation and adsorption. What should we do if the 4a molecular sieve is improperly stored or seriously damped during use?
1. Close the main tower inlet valve, just switch the molecular sieves of the two tanks for adsorption, and use the air behind the molecular sieves without water to regenerate the molecular sieves. However, when the molecular sieves without water are switched to operation, the water behind them will enter the molecular sieves without water. These two molecular sieves both contain water, and then regenerate each other. With adsorption regeneration, the water content decreases, and finally achieve simultaneous adsorption.
2.Directly heating and drying 4a molecular sieve to dehydrate it as soon as possible and restore its adsorption capacity; However, after a large amount of water enters the molecular sieve, when using the above method to regenerate, both molecular sieves will generate a large amount of water, both of them will regenerate and eventually lose their adsorption capacity. The reason is: after a large amount of water enters the zeolite, the water reacts with the zeolite, and the water changes from the free state to the crystal water of the zeolite. Even if the regeneration temperature is 200 degrees, the crystal water cannot be removed, and the adsorption function of the zeolite can only be restored after it is returned to the furnace at 400 degrees by the manufacturer!
Therefore, when the molecular sieve absorbs water in a large area and is affected with moisture, the operation shall be stopped immediately and regeneration shall be carried out. If the adsorption cannot be restored by the above two methods, the manufacturer shall be contacted as soon as possible to rework the calcination.
4a Molecular sieve activation and regeneration method:
1. 4a Change of zeolite temperature, namely “variable temperature”
The adsorbate is removed by heating the molecular sieve. Generally, molecular sieves used in industry are preheated and reheated, purged to about 200 ℃, and the desorbed adsorbate is taken out.
2. Change the relative pressure of 4a zeolite
That is, in the process of gas phase adsorption, the basic method is to keep the temperature of the adsorbent constant, and remove the adsorbate through decompression and back blowing of inert gas.
In the regeneration process of 4a molecular sieve, attention should be paid to avoiding large amount of water inflow, interaction between water and molecular sieve, and the transformation of water from free state to crystalline state. Even if the regeneration temperature reaches 200 ℃, it is difficult to remove crystalline water. If the feeding time exceeds 10 minutes, and obvious water stains can be seen after the regeneration gas is vented, it can be judged that the molecular sieve needs to be returned to the furnace without regeneration.
Post time: Nov-23-2022