Catalysis in which the catalyst is in a different phase than the reactants and products is known as heterogeneous catalysis. This can refer to the physical state of a substance, such as solid, liquid, or gas, as well as immiscible fluids. Reactants adsorb onto binding sites on the catalyst's surface in heterogeneous catalysis, and the availability of these reaction sites might restrict the rate of heterogeneous reactions.
Heterogeneous catalysis has several advantages. They can be easily isolated from a reaction mixture using simple methods like filtration. This allows for the easy and effective recovery of expensive catalysts, which is a crucial factor for industrial manufacturing operations and for this reason they play an important role in industrial chemical production.