Chemical stability of molecular sieve

Acid-resistant: The chemical stability of molecular sieve is affected by its backbone structure and cation type.

Sodium-type molecular sieve (such as 4A, 13X): sensitive to alkaline environment and easy to react with acid.

Hydrogen-type molecular sieve (such as H-ZSM-5): has high acid catalytic activity and is suitable for acid catalytic reactions.

Metal exchange molecular sieve (such as Cu-ZSM-5): Its acid-base and catalytic properties can be adjusted through cation exchange.

Molecular sieve catalytic properties

Acid catalytic activity: The acid catalytic activity of a molecular sieve is related to the aluminum content and cation type in its skeleton.

High aluminum content molecular sieve (such as Y-type molecular sieve): It has strong acidity and is suitable for cracking, isomerization and other reactions.

Low aluminum content molecular sieve (such as ZSM-5): It has medium acidity and is suitable for shape selection catalytic reactions.

Shape selection catalysis: The pore structure of the molecular sieve can limit the diffusion of reactant molecules, thereby achieving selective catalysis. For example, the pore structure of ZSM-5 molecular sieve makes it highly selective in methanol to olefin (MTO) reaction.

Molecular sieve ion exchange properties

Cation exchange capacity: The cations of molecular sieves (such as Na⁺, K⁺, Ca²⁺) can be exchanged by other cations, thereby changing their performance.

Sodium type molecular sieve: It can be converted into hydrogen, calcium or other types of molecular sieve through ion exchange.

Calcium molecular sieve: It has stronger adsorption ability to polar molecules (such as water) and is suitable for gas drying.