External Diffusion Limitation: This occurs when the transport of reactants from the bulk phase to the external surface of the catalyst is slow. It is often influenced by factors such as fluid dynamics and mass transfer coefficients. Internal Diffusion Limitation: This occurs when the transport of reactants within the pores of the catalyst is slow. It is influenced by factors such as pore structure, particle size, and the effective diffusivity of the reactants within the pores.
