An industrial process converts substrate Q into either product D or product E by two…
CHEMISTRY · Multi-part · AP · Chemistry · Thermodynamics and Electrochemistry · Thermodynamics and Electrochemistry
Problem
An industrial process converts substrate Q into either product D or product E by two independent catalytic pathways.
• Catalyst M lowers the activation energy for the Q → D pathway but does not affect the Q → E pathway.
• Catalyst N lowers the activation energy for the Q → E pathway but does not affect the Q → D pathway.
In a pilot plant, engineers run three continuous-flow reactors at 350 K and a fixed residence time.
Reactor 1 Contains no catalyst.
Reactor 2 Contains immobilized catalyst M.
Reactor 3 Contains immobilized catalyst N.
The steady-state product streams are analyzed, and the following mole fractions are obtained:
Reactor 1: D = 0.40, E = 0.60
Reactor 2: D = 0.85, E = 0.15
Reactor 3: D = 0.10, E = 0.90
Assume that all reactions are irreversible under the process conditions and that mass transfer limitations are negligible.
(a) Using the data above, discuss what the relative magnitudes of the uncatalyzed rate constants kD0 and kE0 must be at 350 K. Support your answer quantitatively or qualitatively, as appropriate.
(b) Explain how the introduction of catalyst M changes the product distribution, and infer whether product D is the kinetic or the thermodynamic product. Provide a clear justification.
(c) Propose an additional temperature-variation experiment (describe temperature range and measurements) that would allow you to confirm your conclusion in part (b). Specify the expected outcome if your interpretation is correct.
(d) Suppose both catalysts are blended together in a single reactor at 350 K. Predict the resulting product distribution and justify your prediction based on the concepts of kinetic and thermodynamic control as well as catalyst specificity.