Mass Balances for the One-Dimensional Model

The reaction rate expressions for heterogeneous catalytic reactions are based on the catalyst mass or the surface area. This implies that the generation rate of component i is given by 

To relate these reaction velocities to the reactor volume, a new concept, the catalyst bulk density, pb, is introduced. The catalyst bulk density gives the catalyst mass per reactor volume  

The generation rates of component i, on the basis of the reactor volume, are therefore given by 

After inserting the definition. Equation 5.11 into Equation 5.10, and allowing AV — 0, the balance Equation 5.10 is transformed to 

For a system with one single chemical reaction. Equation 5.12 assumes a new form  

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