The homogeneous platinum catalyst has high activity and reaction selectivity, but because it is in the same phase with the reactants, it is difficult to separate after the reaction and can not be reused, so the cost is high and may bring heavy metal ion pollution. Therefore, researchers immobilized homogeneous catalysts into heterogeneous catalysts. The fixation of homogeneous catalyst is to combine homogeneous catalyst with solid support by physical or chemical methods to form a special catalyst. Heterogeneous platinum catalysts belong to different phases from the reactants, and the common form is the solid catalyst catalyzing the addition reaction of the liquid reactants.
Heterogeneous catalysts for the addition of hydrogen silane can be divided into two types: traditional heterogeneous platinum catalysts and polymeric metal complex catalysts. Among them, the traditional heterogeneous catalysts are formed by adsorbing the transition metal on inorganic particles such as carbon black and alumina. These catalysts have high stability and can be recycled, but their catalytic activity and selectivity are low, and the reaction process requires high temperature and pressure. Polymeric metal complex catalyst is composed of polymeric support, ligand group bonded to the support and transition metal. In general, although heterogeneous catalysts have the advantages of high stability, recycling and reuse, their application is limited due to their low activity and selectivity, complex preparation process, and reduced catalytic activity when reused.
There are many substances that can make the platinum catalyst "toxic", causing its catalytic activity to decrease or even lose its activity. For example, organic compounds containing elements such as nitrogen, phosphorus and sulfur, and ionic compounds containing heavy metals such as tin, lead, mercury, bismuth and arsenic. Therefore, special attention should be paid to the use of platinum catalyst to avoid exposure to these substances that can make it toxic. There are many types and forms of platinum catalysts, so in the application process, according to the characteristics of the reaction system, to choose the appropriate platinum catalyst, in order to achieve the best catalytic effect.