Page 357 - Elements of Chemical Reaction Engineering Ebook

328 Multiple Reactions Chap. 6

(b) For a catalytic weight of 50 kg, determine the exit concentrations from a
“fluiciized” CSTR at 848 K. (Am.: CB = 0.3 mol/dm3)
(c) What is the selectivity of B to C and of B to D in the CSTR?
(d) Plot the concentrations of all species as a function of PBR catalyst
weight (up to 10 kg) assuming isothermal operation at 848 K.
(e) What feed conditions and reactor or combinations of reactors shown in
Figure 6-3 would you use to maximize the production of maleic anhydride?
(f,) How would your results in part (d) change if pressure drop were taken
into account with (Y = 0.099 kg cat.-’ in PBR? Make a plot similar to
that in part (d) and describe any differences.
P6-15B (a) Rework Exwnples 6-6 &6-7 for the case where the toluene formed in
reaction (E6-6.2) can also undergo hydrodealkylation to yield benzene, B:
H+T - B+Me (P6-15.1)
The rate law is

r, = k3CTCr (P6- 15.2)
with k, = 11.2(ft3/lb m~l)O.~/h.
Include the concentrations of toluene and benzene in your results. The
feed conditions given for Examples 6-6 and 6-7 apply to the case where
all three reactions are taking place.
(b) Vary the ratio of hydrogen to mesitylene (1 < OH < 20) and describe
what you find.
(c) pat reactor schemes and feed conditions do you suggest to maximize
SXT ? S,?
(d) Suppose that the activation energies were E, = 20,000 cal/mol, E, =
10,000 callmoi, and E, = 30,000 cal/mol. What temperature would you
recommend for the CSTR size in Example 6-7?
P6-& The following hydrodealkylation reactions occur over a Houdry Detol catalyst
near 800 K and 3500 Wa:
112
(1) H2+C6H(CH3)S C6H2(CH3)44-CH4 -rCll = klCHZ ‘11
112
(2) H2 + C6H2(CH3)4 ___+ C6H,(CH3)3 + CHt -rclo = ~zCH, CIO
112
(3) H2 CgH,(CH3)3 + C6H.+(CH& + cH4 -reg = k3cH2 c9
1 I2
(4) Hz 4- C,H,(CH3)2 d C~HS(CH~) CH, -rC8 = k4c~~
4-
cg

The feed is equimolar in hydrogen and pentamethylbenzene.
(a) For an entering volumetric flow rate of 1 m3/s, what ratio of hydrogen to
pentarnethylbenzene and what PFR reactor volume would you recorn-