Molecular sieve manufacturer: synthesis of large crystal natural molecular sieves and large crystal molecular sieves

The synthesis of large particle molecular sieves is of interest because it can meet many research requirements, such as crystal structure analysis, fine structure analysis, and research on crystal growth mechanisms, adsorption, and diffusion to determine electrical anisotropy, magnetic, and optical properties. For example, although small molecular sieve particles have a high specific surface area and exhibit excellent properties in heterogeneous catalysis, large particle molecular sieves can exhibit better selectivity in shape selective catalysis of molecular sieves. This is because the internal surface area of molecular sieves accounts for a large proportion of the total specific surface area.
Molecular sieves can be formed into different structural types through periodic connections of tetrahedral primary structural units. These tetrahedral primary structural elements can be continuously connected to form more complex composite structural elements, such as rings. These rings can further form a cage. The type and connection mode of structural units are fundamental factors that determine the morphology of molecular sieves, especially the morphology of individual molecular sieves. Another important significance of understanding structural units is to understand molecular sieve crystals, which means that crystal morphology and grain size can be controlled.
In nature, large molecular sieves can be found in volcanic sedimentary rocks, which are generally believed to be formed by the remelting of volcanic glass stones. The typical morphology is a prismatic polyhedron or acicular fibrous zeolite with a size of several centimeters. In nature, molecular sieves generally grow under hydrothermal conditions in the earth's crust, which is also known as a closed hydrothermal environment. At the same time, natural molecular sieves are often associated with other silicate minerals, such as clay and dense silicon species, and their chemical composition varies depending on their origin.
Large single crystal molecular sieves can be synthesized by some good methods. Currently, it is possible to study the crystal structure, crystallization mechanism, and related morphology of molecular sieves in detail. Therefore, the synthesis of large single crystal molecular sieves is particularly important for the determination of molecular sieve structure and the study of its mechanism. Although new analytical methods have recently been developed using X-ray powder diffraction combined with sensitive spectroscopy methods, allowing the determined structure of polycrystalline powders to withstand testing, X-ray powder diffraction can accurately characterize the structural characteristics of molecular sieves, including the positions of skeleton and non skeleton atoms in molecular sieves. Therefore, it has become possible to repeatedly synthesize molecular sieves with submicron structure and large grain molecular sieves.
In the synthesis process of submicron molecular sieves, the nucleation rate is faster, and the general synthesis conditions are monomer silicon source, aluminum source, high alkalinity, and low crystallization temperature. The conditions for synthesizing large particle molecular sieves are generally: a silicon source with low water solubility, using fluorine ions as mineralizers, and a higher crystallization temperature. These methods mainly reduce the nucleation rate or crystallization rate, which can be achieved by adding chemical reagents to the system or applying new synthesis conditions. Hunan Providence New Materials Co., Ltd is a professional molecular sieve manufacturer which can provide USY zeolite, NaY zeolite, REY zeolite, ZSM-5 zeolite, welcome to consult.