The core composition of the vast majority of industrial catalysts can be categorized into three functional parts, though specific compositions vary significantly depending on the application:
Three Core Components
Active Component
This is the functional heart of the catalyst, directly providing the active sites for the catalytic reaction; without it, the target reaction can hardly proceed efficiently. Common materials include metals such as platinum, palladium, and nickel, as well as transition metal oxides and sulfides; in some cases, the active component is formed through the synergistic combination of multiple substances.
Support (Carrier)
Its primary role is to support and disperse the active component, significantly increasing the active component's specific surface area while enhancing the catalyst's structural stability and thermal conductivity. Common materials include alumina, silica gel, activated carbon, and honeycomb ceramics.
Promoter
These substances possess little to no catalytic activity on their own but can optimize the electronic structure and crystal morphology of the active component. They further enhance catalytic activity and reaction selectivity while extending the catalyst's service life.
Examples of Catalyst Compositions in Typical Applications
Catalyst compositions differ markedly across various fields; a few common examples are provided below:
Automotive Three-Way Catalyst: The active core consists of precious metals such as platinum, palladium, and rhodium, combined with an alumina coating and cerium-based rare-earth oxygen storage materials; the support is typically honeycomb cordierite ceramic.
Ammonia Synthesis Catalyst: Features an iron-based active component at its core, supplemented by promoters and a high-temperature-resistant support.
Thermal Power Plant Denitrification Catalyst: Uses V₂O₅ as the active component and TiO₂ as the primary support, supplemented by promoters such as WOₓ and MoOₓ.
