Example 1.8: Propylene oxide decomposes according to first order kinetics. Pure propylene oxide is entering the reactor at a rate of 1 mol/s. The reaction rate constant is estimated to be 4.84 ´ 10^-3 s^-1. Initial concentration of propylene oxide is 0.07 mol/L. Reaction is conducted at 500 °C. If reactor is operated at constant volume and 80 % conversion is required, what should be the size of the plug flow reactor (PFR)?

Solution

Fractional volume change, ε = 0.

Conversion, X_A = 0.8

Reaction rate constant, k = 4.84 ´ 10^-3 s^-1

C kτ_p (Replace t_b with τ_p in Equation 1.40):

C Residence time in plug flow reactor, t_p = 1.609/(4.84´10^-3) = 324 s.

Molar flow rate of reactant A, F_Ao = 1 mol/s

1. Concentration of A in the feed, C_Ao = 0.07 mol/L

C Volumetric flow rate, u (Equation 1.48):

C Reactor volume, V (Equation 1.49):