Heterogeneous Catalysis
Catalysis in which the catalyst is in a different phase from the reactants, usually a solid with gaseous or liquid reagents.
Unit
Dimensionless
In depth
Reaction occurs at active sites on the catalyst surface through adsorption, reaction and desorption. Only the surface participates, so catalysts are made porous or finely divided to maximise area. Separation is trivial, which is why almost all large-scale industrial catalysis is heterogeneous.
Examples in the real world
Solid iron in ammonia synthesis; platinum and rhodium on a ceramic honeycomb in a car exhaust.