Mass transfer and chemical reaction in a catalyst pellet

MASS TRANSFER AND CHEMICAL REACTION IN A CATALYST PELLET 

When an irreversible chemical reaction is carried out in a packed or fluidised bed composed of catalyst particles, the overall reaction rate, is influenced by  

In general, the concentration of the reactant will decrease from CAo in the bulk of the fluid to CAi at the surface of the particle, to give a concentration driving force of CAo - CAi)-Thus, within the pellet, the concentration will fall progressively from CAi with distance from the surface. This presupposes that no distinct adsorbed phase is formed in the pores. In this section the combined effects of mass transfer and chemical reaction within the particle are considered, and the effects of external mass transfer are discussed in Section J 0.8.4. 

In the absence of a resistance to mass transfer, the concentration of reactant will be uniform throughout the the whole volume of the particle, and equal to that at its surface 

The reaction rate per unit volume of particle 5H, for an nth-order reaction is then given by  

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