Chemical bonding method. This method is now widely used in the manufacture of polymerization catalysts. Its purpose is to solidify homogeneous catalysts. Supports capable of chemically bonding with transition metal complexes have certain functional groups on their surface (or functional groups are added after chemical treatment), such as -X, -CH2X, and -OH groups. These supports are reacted with phosphine, arsine, or amines to phosphinate, arsine, or amination. Then, the lone pairs of electrons from phosphorus, arsenic, or nitrogen atoms on the surface are used to coordinate and complex with the central metal ion of the transition metal complex, thus obtaining a chemically bonded solid-phase catalyst, such as the Ziegler-Natta catalyst used in the bulk liquid-phase polymerization of propylene.
Fiberization method. Used for the manufacture of catalysts supported on noble metals. For example, borosilicates are drawn into glass fibers, etched with concentrated hydrochloric acid solution to become porous glass fiber supports, and then impregnated with chloroplatinic acid solution to load platinum components. Depending on the practical application, the fiber catalysts are pressed into various shapes and required densities; for example, catalysts used for automotive exhaust oxidation can be compressed into a short cylindrical tube. Carbon fibers can also be used if the process is not oxidation. However, the manufacturing process of fiber catalysts is more complex and costly.
