Catalytic Cycle

A catalytic cycle in chemistry is a term for a multistep reaction mechanism that involves a catalyst. The catalytic cycle is the main method for describing the role of catalysts in biochemistry, organometallic chemistry, materials science, etc. Often such cycles show the conversion of a precatalyst to the catalyst. Since catalysts are regenerated, catalytic cycles are usually written as a sequence of chemical reactions in the form of a loop. In such loops, the initial step entails binding of one or more reactants by the catalyst, and the final step is the release of the product and regeneration of the catalyst. Articles on the Monsanto process, the Wacker process, and the Heck reaction show catalytic cycles.

A catalytic cycle is not necessarily a full reaction mechanism. For example, it may be that the intermediates have been detected, but it is not known by which mechanisms the actual elementary reactions occur.

Catalytic cycles also have an important role in the atmosphere, for example in the reactions that lead to ozone depletion. The complicated interplay between different schemes, including null cycles that have no overall effect, determines the rate of production and destruction of many atmospheric components.