Adsorption theory of Heterogeneous Catalysis :1. The reactants diffuse to the surface of the catalysts. In this process, the reactants first get in contact with the external surface out of which some of them get enter into interior through the cracks on the external surface.
2. These molecules then get adhered to the suitable sites available for adsorption.
3. The reactants, when bound to the surface have a higher probability of reacting with each other, and after the reaction, they form an intermediate compound.
4. After this process, the intermediate compound gets desorbed from the surface, which again becomes available for adsorption for other molecules to come.
5. The intermediate compound then disintegrates to form the final products, which then diffuse out of the internal pores and the external surface of the catalyst.