Three Way Catalyst Honeycomb Metal Substrate

The chemical properties of transition metals are closely related to the d orbitals of transition metal atoms. The fraction of d orbital involved in forming metal bond (d%) has a certain relationship with the catalytic activity of metal. In view of the high degree of dissociation of electrons in metal bonds, the study of metal catalysis should first consider the electron migration as a metal integrity and the remote electron interaction between metal atoms. In the 1950s, the band theory of solid state physics was applied to describe the electronic structure of metal and semiconductor catalysts. When the transition metal atom forms a solid, the outermost s and d orbitals of the atom form bands, respectively, and the s and d bands overlap each other, and the outer electrons will be redistributed in the s and d bands depending on the level of the energy level. Therefore, the concept of "D-hole" can also be used to describe the d state of the transition metal. The larger the d%, the fewer "D-holes".

Industrial Metal Catalytic Converter Due to the formation of metallic bonds, when discussing the structure of the active center on the metal surface, it is necessary to take into account the influence of the nearest and second-nearest atoms around the atoms constituting the active center. In the metal phase, each atom is surrounded by the same number of nearest neighbors, and atoms at different parts of the surface have different numbers of nearest neighbors. The greater the degree of coordination unsaturation, the greater the chemical effect on the foreign adsorbed molecules. For metal catalysts, an atomic group (atomic cluster) composed of a certain number of surface atoms can be used to approximate the role of the entire metal. The larger the number of atoms contained in an atomic cluster, the closer its effect will be to the actual situation, but the theoretical study will undoubtedly increase the greater difficulty. Metal cluster complexes can be used as models for the active centers of metal clusters. The concept of using the active center of atomic clusters in Square Metal Catalyst will connect the three fields of heterogeneous, homogeneous and metalloenzyme catalysis.