Catalysis technology serves as a core pillar in modern chemical industry, energy conversion and environmental governance. As the functional core of catalysts, active sites are the micro locations where all catalytic reactions take place, directly governing catalyst activity, selectivity and stability. The bulk carrier and framework of a catalyst barely participate in chemical reactions; they mainly support active components, disperse metal particles and facilitate mass transfer. Only specific micro regions on the surface or inside pore channels can activate reactants and reconstruct chemical bonds, and these critical regions are defined as active sites.
Active sites are the only functional zones that drive catalytic reactions. Their unique surface structure and electronic state lower the activation energy of chemical reactions, enabling hard-to-trigger reactions to proceed under mild operating conditions. The catalytic cycle repeats continuously: first, active sites adsorb reactant molecules and weaken internal chemical bonds; then they break old bonds and form new ones to generate target products; finally, products desorb from the sites, restoring the original structure of active sites for subsequent reaction cycles.
Different catalysts feature distinct active sites. For metallic catalysts, active sites are mostly edge and corner atoms on metal particles, widely applied in hydrogenation and reforming reactions. Solid acid catalysts such as molecular sieves rely on acid sites to crack heavy oil and isomerize hydrocarbons. Oxide and sulfide catalysts center on defect vacancies and interface sites, commonly used for flue gas desulfurization and denitrification in environmental protection.
Catalyst performance is fully determined by the status of active sites. The quantity of active sites controls reaction conversion efficiency, while site strength regulates selectivity to produce designated target products. During industrial operation, carbon deposition coverage, impurity poisoning, high-temperature sintering and structural damage will deactivate active sites, which fundamentally leads to the decline and failure of catalysts.
The core objective of current catalyst research and development is to adjust the quantity, structure and microenvironment of active sites via scientific preparation methods. This produces catalytic materials with higher activity, superior selectivity and longer service life, realizing high-efficiency, eco-friendly and cost-effective industrial reactions.