## Transcribed Text

Problem 1
Consider a system with three liquid-phase reactions, one of which is
desired and the others undesired.
1) A + B
C (desired);
T1 ==12CAC
2)
A
D (undesired);
= k2CA
1+KACA
3) 2B E (undesired);
a (5 pts).
Express the production rate of each species in terms of reaction
rates.
b
(15
pts). Assume that all rate constants are known and that you can
choose CAf and CBf, the feed concentrations of A and B,
respectively. Given a choice between a single CSTR or a PFR
to produce the desired product, C, is there an obvious choice?
Explain why or why not. If not, explain the conditions that
would sway you towards choosing a single CSTR versus the
conditions that would sway you towards choosing a PFR.
C (20 pts). For each of the single CSTR and PFR configurations, write
down all of the equations that you would need to solve in order
to compute the concentration of C leaving the reactor. For any
differential equations, do not forget to specify any
initial/boundary conditions. You do not need to solve or simplify
these equations.
d (10 pts). Is there a configuration with multiple CSTRs in series that might
outperform both of the single reactor types? Explain why or
why not.
Problem 2
Consider the following overall reaction accelerated by a solid catalyst.
A(g) B(g)
C(g) + D(g)
Regarding the mechanism of this reaction, it is known that all four of the
major (gas-phase) species reversibly adsorb to catalyst sites. All catalyst
sites are identical, and all adsorbed species (A+X, B.X, C.X, and D.X)
occupy 1 site. Adsorbate-adsorbate interactions are negligible.
a
(20 pts). Assuming that adsorption/desorption of all 4 species are close
to equilibrium, derive expressions for each adsorbed species,
in terms of gas-phase concentrations and constant
parameters.
b (10 pts). The elementary reaction that occurs on the catalyst surface is
unknown, but it may be assumed to be essentially irreversible
and rate-limiting. Two different alternatives have been
proposed:
i) A.X + B.X C.X + D.X
ii) A(g) + B.X C.X + D(g)
For each of these schemes, derive a compact expression for
the overall reaction rate, applying your results from part a.
C (20 pts). Suppose that you have the ability to control the gas-phase
composition, such that any one of the species concentrations
may be varied while keeping the others constant, and to
measure the corresponding change in reaction rate. Describe
two different experiments that could distinguish between the
surface reactions proposed in part b. Explain how the results of
each experiment would favor one of the two schemes and rule
out the other.

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