catalystsubstances
Catalyst substances are chemical species that increase the rate of a chemical reaction without undergoing permanent chemical change themselves. A catalyst works by providing an alternative reaction pathway with lower activation energy, thereby increasing the fraction of molecules that react per unit time. Although catalysts participate in reaction steps, they are regenerated by the end of the cycle and remain present after the reaction, in principle unchanged. In practice some catalyst material may be consumed or lost by side processes or deactivation, but the net transfer of mass is typically zero.
Catalysts are broadly classified by phase: homogeneous catalysts are in the same phase as the reactants (for
Key properties include activity (rate enhancement), selectivity (chemoselectivity, regioselectivity, stereoselectivity), and stability under operating conditions. Metrics
Applications span industrial synthesis, energy conversion, and environmental protection. Iron catalysts enable ammonia synthesis; platinum-group catalysts