Consider a series-reaction network composed of two first-order reactions: A
C. It is assumed that B is the desired product, which yields
, which are plotted versus the conversion for various values of the ratio
in this Demonstration. Yield and selectivity are plotted in red for the PFR (plug flow reactor) and in green for the CSTR (continuous stirred-tank reactor). Yield and selectivity will have low values if one operates at high conversions. Thus there is a trade-off between conversion of reactant A and selectivity for component B. For high values of
, the selectivity drops sharply with conversion. On the other hand, when
is small, there is a large range of conversion values for which the selectivity is still high enough, especially for the PFR reactor. It is clear from the results that a recycling of some unreacted reactants will be necessary.