Introduction of Zeolite Molecular Sieve
The first discovery of natural zeolite was in 1756. In the 19th century, people had a further understanding of the microporous properties of natural zeolites and their performance in adsorption and ion exchange. However, until the 1940s, zeolite chemists headed by RM Barrer, imitating the formation environment of natural zeolite, successfully synthesized the first batch of zeolite molecular sieves with low silicon-aluminum ratio (ie SiO2 and Al2O3 molar ratio) under hydrothermal conditions. It has laid an important scientific foundation for the development of molecular sieve industry and porous material science from the 20th century to the 21st century.
The common feature of microporous compounds and porous materials with porous compounds as the main body is that they have a regular pore structure, including the size and shape of the pore and window, the dimension of the pore, the direction of the pore, and the composition and properties of the pore wall. . The size of the pore channel is the most important feature of the porous structure. Until now, people have called the pore channel with a size below 2 nm as the micropore, and the substance with regular micropore channel structure is called the microporous compound or can be further processed. Molecular Sieve. The pore size range of 2~50nm is called mesopore, the substance with ordered mesoporous pore structure is called mesoporous material, and the pore size larger than 50nm belongs to the macropore range.
Let’s take microporous compounds as an example to briefly introduce the development of microporous compounds: According to the statistics of the previous structure committees of the International Molecular Sieve Association (IZA), there were 27 independent structures of microporous molecular sieves in 1970, and it rose to 38 in 1978. The number of molecular sieves rose to 64 in 1988, 98 in 1996, and 133 in 2001. According to a report in 2007, the total number of molecular sieve structures had reached 176, and by 2013, the total number of structures had reached 213. . In fact, for more than half a century, due to the progress of the synthesis chemistry and synthesis technology of microporous compounds, a large number of framework constituent elements have been expanded (from Si and Al, which are the constituent elements of zeolite, to a large number of transition elements and BCNPAs.S.Se, etc.). Dozens of elements, including non-metallic elements, have been used as constituent elements of microporous frameworks) and the diversification of related basic structural units, the modulation of frameworks and the advancement of secondary synthesis methods, and various types of microporous skeletons have been synthesized and developed. There are countless porous compounds, and the development of various types of microporous materials based on them is even more rapid. Since scientists from Mobil Corporation reported the successful synthesis of M41S series mesoporous materials in 1992, mesoporous materials and related sciences have also developed rapidly for more than two decades. The research and development of ordered macroporous materials has also shown the particularity of its structure and properties in some aspects.
From micropores to mesopores to macropores,
all molecular sieves and porous materials, the composition of their regular
pore skeletons are all pure inorganic compounds, until in the past decade,
coordination polymers, inorganic-organic hybrid substances, metal oxygenates
Compounds, and ordered porous frameworks with pure organic frameworks as the
main body, such as MOFs, COFs, etc., have emerged in large numbers, and have
shown many features in structure and function, which has added a new scientific
field to the chemistry of porous materials, and is related to The
diversification and application scope of porous materials have opened up new
directions, and further development has broadened the horizons.
