Reaction in a Single Catalyst Pellet

Consider a gas-phase reaction A—taking place in the presence of a catalyst X. Assume that this reachon is carried out in a packed bed reactor in which the gas stream 

Reaction of A in the gas stream in contact with the solid catalyst pellet involves the following steps  

Transfer of A from the bulk gas to the pore mouth at the catalyst surface across the gas film resistance. This transfer occurs at a rate r and the driving force is - Cas), where Cas is the concentration of A at the catalyst surface. 

Single pore in a catalyst pellet in contact with fluid stream. 

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