A precious metal catalyst is a precious metal material that can change the speed of a chemical reaction without itself participating in the reaction products. Almost all precious metals can be used as catalysts, but platinum, palladium, rhodium, silver, ruthenium, etc. are commonly used, among which platinum and rhodium are particularly widely used. Their electron orbits are not filled, the surface is easy to adsorb reactants, and their strength is moderate, which is conducive to the formation of intermediate "active compounds" and has high catalytic activity. They also have comprehensive excellent properties such as high temperature resistance, oxidation resistance, and corrosion resistance. Become an important catalyst material.
Three major functions of precious metal catalysts:
(1) Activity. It is a standard for measuring the effectiveness of catalysts. In industry, it is usually expressed by the quantity of products obtained per unit volume (or weight) of catalyst under certain conditions and per unit time.
(2) Selectivity. It refers to the specificity of the catalyst's action, that is, under certain conditions, a certain catalyst only accelerates a certain chemical reaction. Selectivity is usually expressed as a percentage of the ratio of the number of moles of the expected product obtained after the reaction to the number of moles of raw materials participating in the reaction.
(3) Stability. It refers to the ability of a catalyst to maintain its activity and selectivity during use, usually expressed in terms of service life. The good performance of the catalyst not only depends on the inherent characteristics of the active metal (the electronic structure of the atoms, etc.), but also depends on factors such as its crystal structure, particle size, specific surface area, pore structure, and dispersion state. In addition, cocatalysts and carriers also have an important impact on the performance of the catalyst.

Platinum catalyst