Page 535 - Elements of Chemical Reaction Engineering Ebook

Sec. 8.7 Nonisothermal Multiple Chemical Reactions 505

m
uA(T,- T)-I’,,CO,C,,(T-To)fVrlAhHRx,~(T)+ VF-~AA&~~A(T) 0
=
1=1
(8-92)
One of the major goals of this text is to have the reader solve problems irvolv-
ing multiple reactions with heat effects (cf. P8-30).

Example 8-I;? Multiple Reactions in a CSTR

The elementary liquid-phase reactions

take place in ai 10-dm3 CSTR. What are the effluent concentrations for a volumetric
feed rate of 10 dm3/min at a concentration of A of 0.3 mol/dm3?
The inlet temperature is 283 K.
Additional information:

CpA = Cpg = CPc = 200 J/mol. K

kl = 3.03 rnin-l at 300 K, with E, = 9900 cal/rnol
k2 = 4.58 min-l at 500 K, with E2 = 27,000 cal/mol
AH,,, = -55,000 J/mol A .IIA = 40,000 J/min.K with T, = 57°C
AH,,,, = -71,500 J/mol B

Solution
A: Combined mole balance and rate law for A:

V= ‘0 (cAO - (E8-12.1)
kiCA
Solving for CA gives us
CA = - (E8-12.2)
cAO
1 +rk,
B: Combined mole balance and rate law for B:

(E8- I! 2.3)

Solving for CB yields
c*=-- rkICA - rki cAO
1 + .ck, (1 + %k,)( 1 + rk,) (E8-12.4)