Development History Of Molecular Sieves

There are two types of molecular sieves: natural zeolite and synthetic zeolite Natural zeolite is mostly formed by the reaction of volcanic Tuff and tuffaceous Sedimentary rock in marine or lacustrine environments. At present, more than 1000 kinds of zeolite minerals have been found, 35 of which are more important. The common ones are clinoptilolite, mordenite, Erionite and rhombolite. It is mainly distributed in the United States, Japan, France and other countries. China has also found a large number of mordenite and clinoptilolite deposits. Japan is a country with mining output of natural zeolite. ② Due to resource limitations of natural zeolite, synthetic zeolite has been widely used since the 1950s. More than 200 years ago, B. Kronstedt named aluminosilicate zeolite, and the general chemical composition formula is: M and n are metal ions and their valence numbers; X is the molecular number of silica; Y is the number of molecules of water; P is the atomic number of aluminum; Q is the atomic number of silicon. Molecular sieves are used as solid adsorbents in the chemical industry, and the substances adsorbed can be desorbed. Molecular sieves can be regenerated after use. It is also used for the drying, purification, separation, and recovery of gases and liquids. Since the 1960s, it has been used as a cracking catalyst in the petroleum refining industry, and various molecular sieve catalysts have been developed for different catalytic processes.