What role does adsorption play in heterogeneous catalysis ?

Explanation

In heterogeneous catalysis, the reactants are generally gases while catalysts are solids. The reactant molecules are adsorbed on the surface of the solid catalyst by physical adsorption or chemical adsorption. As a result, the concentration of the reactant molecules on the surface of the catalyst increases and hence the rate of reaction also increases.
Alternatively, one of the reactant molecules undergo fragmentation on the surface of the catalyst producing active sites which make the reaction fast. The product molecules, on the other hand, have no affinity for the solid catalyst and therefore, undergo desorption leaving the surface free for further fresh adsorption. This theory is called adsorption theory.