Multiple reactions

This chapter evaluates how the design process must be modified when more than one reaction is occurring. It considers parallel reactions. Treatment must be different when there are reactions of mixed reaction rate orders proceeding at the same time, and the local or instantaneous selectivity depends upon the concentration of reactant. In such a case, the choice of reactor will influence the overall selectivity. For a continuous stirred tank reactor (CSTR), the overall selectivity is equal to the local selectivity as the local selectivity is a constant because of the lack of concentration gradients. Hence, calculation of the product distribution is straightforward. For a plug flow reactor (PFR) or batch reactor, it is more complex to evaluate the overall product distribution as the local selectivity or instantaneous selectivity will vary with position or time.