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