Page 557 - Elements of Chemical Reaction Engineering Ebook

Chap. 1B Questions and Problems 527

The feed to the reactor is equal molar in in both m-xylene and o-xylene (spe-
cies A and B). For a total feed rate of 2 mol/min and the reaction conalitions
below, plot the temperature and the molar flow rates of each species as a func-
tion of catalyst weight up to a weight of 100 kg. .
(a) Find the lowest concentration of o-xylene achieved in the reactor.
(b) Find the highest concentration of m-xylene achieved in the reactor.
(c) Find the maximum concentration of o-xylene in the reactor.
(d) Repeat parts (a) to (d) for a pure feed of o-xylene.
(e) Vairy some of the system parameters and describe what you learn.
(f) What do you believe to be the point of this problem?

Additional information: 24
All heat capacities are virtually the same at 100 Umo1.K.
Cm = 2 mol/dm3
AHRx1* = - 1800 J/mol o-~ylene~~
AHRx30 = - 1100 J/mol o-xy1enez4

k, = 0.5 exp[2(1 - 320/T)] dm3/kg cat:min
k2 = k,/K,
k3 = 0.005 exp{[4.6(1 - (460/T))]) dm3/kgcat:min
Kc = 10 exp[4.8(430/T - 1.5)]
To = 330 K
T, = 500 K
Ua/pb = 16 J/kg cat:min .“C
W = 100 kg
Pa-30, (Multiple reactions with heat effects) Styrene can be produced from ethylben-
zene by the following reaction:
ethylbenzene +--+ styrene + H, (1)

Howevex, several irreversible side reactions also occur:
ethylbenzene __1) benzene + ethylene (2)
ethylbenzene + H, - toluene + methane (3)
[J. Snyder and B. Subramaniam, Chem. Eng. Sci., 49,5585 (1994)l. Ethylben-
zene is fed at a rate of 0.00344 kmol/s to a 10.0-m3 PFR (PBR) along with
inert steam at a total pressure of 2.4 atm. The steam/ethylbenzene molar ratio
is initially [i.e., parts (a) to (c)) 14.5: 1 but can be varied. Given the following
data, find the exiting molar flow rates of styrene, benzene, and toluene for the
following inlet temperatures when the reactor is operated adiabatically.
(a) To = 800 K
(b) To = 930 K
(c) To = 1100 K
-
24 Obtained from inviscid pericosity measurements.