Molecular sieve manufacturer explains the active metals in molecular sieves used for catalytic oxidation reactions

For a long time, molecular sieves have been used as solid acid catalysts. Heavy oil Fluid catalytic cracking is the most common catalytic process in the world, and Y-type molecular sieve is the most important active component of the catalyst used in this process. Acidic molecular sieves have been widely used in the production of many chemicals instead of minerals and L acids, such as alkylation of aromatics and Beckmann rearrangement. By introducing various metals, the redox performance of molecular sieves can be enhanced. Next, the editor of molecular sieve manufacturer will briefly explain the introduction of metals and their related catalytic oxidation reactions.
There are two ways for molecular sieves to introduce heteroatoms: one is to enter the framework of the molecular sieve, and the other is to enter the pores of the molecular sieve. Most molecular sieves have cation exchange ability, which allows trivalent cations (such as aluminum ions) or lower valent cations to isomorphically replace tetravalent framework silicon ions, forming a net negative charge on the framework. And these negative charges can be neutralized by cations in molecular sieve pores or cages, which can be metal cations, metal compounds, or alkyl ammonium salt cations. If cations are transition metals with redox properties, they can serve as active centers for oxidation reactions.
The study of molecular sieve coordination chemistry began in the 1970s. Metal complexes with appropriate size can be encapsulated in molecular sieves, and they are regarded as a bridge between homogeneous and Polyphase system. Compounds with smaller sizes than molecular sieve pores or cages can enter molecular sieve pores or cages; On the contrary, compounds with larger sizes than molecular sieve channels and cage apertures can only be synthesized in situ. Molecular sieves containing transition metals can be synthesized in situ through ligand adsorption or ligand synthesis. Cationic compounds can be adsorbed in molecular sieves by electrostatic interaction. The encapsulation of this complex does not require molecular sieves and their interactions, and its catalytic performance is close to that of homogeneous complexes. Since the first report on the synthesis of metal phthalocyanine complexes in NaY in 1977, well-known metal phthalocyanine complex packaging materials have emerged.
Another method of introducing heteroatoms is similar to the isomorphic substitution of aluminum, where heteroatoms isomorphically replace silicon in the skeleton. In hydrothermal synthesis, due to the influence of the solubility and special chemical behavior of tetrahedral precursor compounds in the synthesized mixture, the types and quantities of non silicon heteroatoms that can enter the molecular sieve framework are limited. Early literature used basic synthesis routes, and Ga, P, and Ge ions had the potential to enter some molecular sieve structures. However, until the late 1970s, researchers mainly focused on exchangeable cationic and non skeletal species. 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.