For hydrosilylation reaction, in addition to hydrosilanes and unsaturated compounds, catalyst is an indispensable component, which plays a role in accelerating the reaction speed, shortening the reaction time and reducing the reaction temperature. The catalysts for hydrosilylation reaction are mainly compounds and their complexes of the Ⅷ B transition metal elements platinum, palladium, nickel and rhodium in the periodic table of elements. Among them, platinum catalysts have the highest catalytic activity and are most widely used.

Platinum catalysts used for hydrosilylation reaction are mainly divided into homogeneous catalysts and heterogeneous catalysts. Among them, homogeneous catalyst and reactant are in the same phase, and there is no phase interface. In hydrosilylation reaction, homogeneous catalyst generally refers to liquid catalyst.

There are three kinds of homogeneous platinum catalysts: the first is to synthesize chloroplatinic acid (H2PtCl6 ▪ 6H2O) is dissolved in ethanol, isopropanol, tetrahydrofuran and other organic solvents to form a complex through interaction, which is called "Speier catalyst". This catalyst is simple, fast and easy to use; The second type of platinum catalyst is the complex of platinum and vinyl double head, called Karstedt's catalyst, which has high reaction activity, can be stored stably, and has good compatibility with various types of polysiloxanes. It is the most widely used catalyst in the addition of organosilicon release agents; The third type of platinum catalyst is chloroplatinic acid, in addition to forming complexes with other unsaturated compounds, also forms complexes with ketones, cyclopentadienes, esters, alcohols, crown ethers, crown ethers containing heteroatoms, and polysiloxanes, which are used as catalysts.

Homogeneous platinum catalyst has high activity and reaction selectivity, but because it is in the same phase with the reactant, it is difficult to separate after the reaction is completed and cannot be reused, so the cost is high, and it may also bring heavy metal ion pollution. Therefore, the researchers immobilized the homogeneous catalyst into heterogeneous catalyst. The so-called immobilization of homogeneous catalyst is to combine homogeneous catalyst with solid carrier by physical or chemical methods to form a special catalyst. Heterogeneous platinum catalysts and reactants belong to different phases, and the common form is that solid catalysts catalyze the hydrosilylation reaction of liquid mixed reactants.

Heterogeneous catalysts for hydrosilylation reaction are mainly divided into two types: traditional heterogeneous platinum catalyst and polymer metal complex catalyst. Among them, traditional heterogeneous catalysts are formed by adsorbing transition metals onto 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. The polymer-metal complex catalyst consists of three parts: polymer carrier, ligand bonded on the carrier and transition metal. In general, although heterogeneous catalysts have the advantages of high stability and recyclability, 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 "poison" the platinum catalyst, resulting in the reduction or even loss of its catalytic activity. For example, organic compounds containing nitrogen, phosphorus, sulfur and other elements and ionic compounds containing tin, lead, mercury, bismuth, arsenic and other heavy metals. Therefore, during the use of platinum catalyst, special attention should be paid to avoid the platinum catalyst contacting with these substances that can make it toxic. There are many kinds and forms of platinum catalysts. Therefore, in the process of application, it is necessary to select appropriate platinum catalysts according to the characteristics of the reaction system to achieve the best catalytic effect.