Zeolite molecular sieve As an inorganic crystal material, it is widely used in catalysis, adsorption, ion exchange and other fields due to its regular pore structure, strong acidity and high hydrothermal stability, and plays an irreplaceable role. The research on the artificial synthesis of zeolite molecular sieve can be traced back to the 1940s. Barrer et al. realized the artificial synthesis of zeolite molecular sieve for the first time through the research on the phase transformation of natural minerals in hot salt solution, which opened the prelude to the artificial synthesis of zeolite molecular sieve

Zeolite molecular sieve

Natural zeolite was discovered earlier, about more than 50 kinds. Their use was seldom developed in the early stage. Their application was mainly limited to the drying, purification and separation of gas. In the 1950s, the artificial synthesis of zeolite A and zeolite X, especially zeolite Y, and its application in catalytic cracking were seen as the beginning of zeolite material industry and commercialization. In the half century since then, the research of zeolite molecular sieves has gone through three main development stages, namely, the synthesis of ZSM-5 in the 1970s, the synthesis of AIPO4-n series molecular sieves in the 1980s, and the synthesis of M4lS mesoporous molecular sieves in the 1990s. At present, there are at least more than 120 kinds of zeolite molecular sieves. The pore size has expanded from micropore to mesopore, and the chemical composition of the skeleton has expanded from aluminum silicate to aluminosilicate and aluminophosphate containing various heteroatoms. It has become an indispensable catalytic and adsorption material in petroleum processing and fine chemical industry.

Zeolite molecular sieve is the hydrate of crystalline aluminosilicate metal salt, and its general chemical formula is: Mx/m [(AlO2) x · (SiO2) y] · zH2O. M represents cation, m represents valence state number, z represents hydration number, and x and y are integers. After the zeolite molecular sieve is activated, the water molecules are removed, and the remaining atoms form a cage structure with a pore size of 3~10&Aring. There are many holes of a certain size in the molecular sieve crystal, and many holes with the same diameter (also called "windows") are connected between the holes. Molecular sieve is named because it can adsorb molecules smaller than its pore size to the inside of the hole, and repel molecules larger than its pore size to the outside of the hole to screen molecules. Zeolite molecular sieves can exist in nature, and the artificial synthesis in large quantities began in the 1970s.