Heterogeneous catalysis is a chemistry term which describes catalysis where the catalyst is in a different phase (ie. solid, liquid and gas) to the reactants.Heterogenous catalysts provide a surface for the chemical reaction to take place on. The reactants are adsorbed onto the surface of the catalyst to weaken the chemical bonds. They then react and the product releases itself from the surface of the catalyst. The synthesis of ammonia is an example of heterogeneous catalysis:

3H₂(g) + N₂(g) ↔ 2NH₃(g) - catalysed by Fe(s)

See also

• Homogeneous catalysis