What role does adsorption play in heterogeneous catalysis?

Explanation

Adsorbents such as Fe, .V, O_3,. finally divided Ni play a very important roole in the catalytical formation of .NH_3. (Haber.s Process), .H_2 SO_4. (Con.tact process). hydrogenation of oils as heterogeneous catalyst respectively. In hetèrogeneous catalysis, the catalyst used is in different phase that the reactants. Basically. it involves the following "steps:
i. Diffusion of the reactants at the surface of the catalyst.
ii. Adsorption of the molecules of the reactant at the atetive sites.
iii. Occtirrence of the chemical reactions on the surface of the catalyst.