Two first-order, liquid-phase reactions A→B→C take
place in an isothermal batch reactor. The reactor initially contains only A at a concentration of 2
mol/L. The activation energy Ea,2 of the second reaction (155 kJ/mol) is higher
than the activation energy Ea,1 of the first reaction
(145 kJ/mol). Vary the
temperature of the reaction with a slider. Select Display: "selectivity" to plot selectivity
(CB/CC) versus time. The selectivity changes with temperature because
the reactions have different activation energies.
Consider the first-order reactions 
. The reactor is isothermal, and
the temperature of the reactor is set with a slider. As the temperature changes, the selectivity
CB/CC for the desired product B changes. Mole balances are
done:
where
CA, CB, and CC are the concentrations of A,
B and C (mol/L), t is time (h), k1 and k2 are the
rate constants for the first and second reactions (1/h), A1 and A2 are
pre-exponential factors (where A1 = 3.6x1016 h-1 and A2 = 1.8x1017 h-1), Ea,1 and Ea,2 are
activation energies (where Ea,1 = 145 kJ/mol and Ea,2 = 155 kJ/mol), R
is the ideal gas constant (kJ/[mol K]), and T is temperature (K) of the reaction.
References
[1] H. Scott Fogler,
Essentials of Chemical Reaction Engineering, Boston: Pearson Education, 2011 pp. 298-302.
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