active site otherwise active centre (rus. катализатора, активный центр) — atom or group of atoms (ions) of an active catalytic phase, whose interaction with molecules (ions, radicals) of reagents or intermediates results in acceleration of chemical reactions.


According to the concepts of active centres, a catalytic process involves not the entire catalyst, but only a small part of it. These are the catalyst’s active sites, which participate in the formation of a specific bond with the initial reagents, leading to the emergence of an intermediate compound, thus accelerating certain reactions (see catalysis). An active site includes the adsorption and catalytic centres; in heterogeneous catalysts they tend to coincide, while in enzymes they can be spatially separated. A catalyst may contain several types of active sites, which allows it to participate in several chemical reactions. Sites that are active in one reaction can be inactive in other reactions.


  • Smirnov Andrey V.
  • Tolkachev Nikolay N.


  1. Setterfild C. N. Heterogeneous Catalysis in Industrial Practice, 2nd edn. — McGraw-Hill, 1991.
  2. Krylov O. V. Heterogeneous Catalysis — Мoscow: IKC "Akademkniga", 2004. — 679 pp.

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