molecular sieve drying is amorphous silicate or silicon aluminate, made of silicon oxygen tetrahedron or alumina tetrahedron by oxygen bridge is linked together to form a molecular size (usually from 0.3 to 0.3 nm) of concreted complete cavity system, which are characteristic of molecular sieve. However, with the deepening of the molecular sieve synthesis and application research, the researchers found that the phosphorus aluminate salts drying molecular sieve, molecular sieve and the skeleton of elements (silicon or aluminum or phosphorus) can also Be composed of B, Ga, Fe, Mn, Cr, Ge, Ti, V, Co, Cu and zinc, Be replaced, the concreted complete cavity also can achieve more than 2 nm, the size of the molecular sieve can Be divided by skeleton elements silicon aluminum type molecular sieve, phosphorus kind of molecular sieve and skeleton heteroatomic molecular sieve; According to the hole size, hole size less than 2 nm, 2 ~ 50 nm, and more than 50 nm molecular sieve respectively called microporous and mesoporous and macroporous molecular sieve. With large aperture, become a good carrier of larger molecular reaction, but for amorphous mesoporous materials of hole wall, causing its water thermal stability and thermal stability is not required for petrochemical industry application harsh conditions
natural gas adsorbent is a kind of crystal type of aluminum silicate, the crystal structure of neat and uniform pore size was in the order of molecular size, it only allows molecules into the smaller than the aperture diameter, so can according to the size of the molecules in the mixture screening. According to molecular sieve. As early as 200 years ago, b. g dragon, he named the first molecular sieve separation, the chemical composition in the general formula for molecular sieve zeolite molecular sieve type M and n are metal ions and the valence; X is the silica on the number of molecules; Y is the number of molecules of water; P is aluminum atomic number; Q is number of silicon atoms. Molecular sieves in chemical industry as a solid adsorbent, by adsorption material can desorption, molecular sieve can be recycled after use. Is also used in gas and liquid, dry, purification, separation and recycling. In the 1960 s, used as cracking catalysts in the petroleum refining industry, has now developed a variety of suitable for different molecular sieve catalysts for catalytic process.