Design of Reactors for Multiple Reactions

Reactors for multiple reactions (series or parallel reactions) are designed to achieve maximum yield or selectivity of desired products (Section 2.1.8). Consider a series reaction 

Cgjr and Cg are the final concentrations of A, B and C in the effluent stream. Taking steady-state molal balance of A, B and C around the CSTR, we get the following equations For reactant A, 

Combining Equations 3.73 and 3.74, we can write overall selectivity Ob in terms of total 

selectivity decreases with an increase in conversion 

For the series reaction A—carried out in a PFR, the equation for overall selectivity derived for the batch reactor (Section 2.1.8) can be used for PFR after replacing the term t (for batch time) in the batch reactor equation by space time x. Thus, for the series 

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