CE 203 Advanced Reaction Engineering
Exercise 1
Instructor: Pedro Castaño
Teaching Assistants: Ali M. Alkadhem, Gontzal Lezcano
February 14, 2022
Problem 1: There are two reactors of equal volume available for your use: one a
CSTR, the other a PFR.
A→B
The reaction is second order, irreversible, and is carried out isothermally.
2
−𝑟𝐴 = 𝑘𝐶𝐴2 = 𝑘𝐶𝐴0
(1 − 𝑋)2
There are two ways you can arrange your system:
Scheme 1: Reactors in series: CSTR followed by PFR
Scheme 2: Reactors in series: PFR followed by CSTR
(a) If possible, which system will give the highest overall conversion?
(b) If possible, which system will give the lowest overall conversion?
Problem 2:
The exothermic reaction 𝑨 → 𝑩 + 𝑪
Was carried out adiabatically and the following data were recorded:
x
—rA (mol/dm3. min)
0
1
0.2
1.67
0.4
5
0.45
5
0.5
5
0.6
5
0.8
1.25
0.9
0.91
The entering molar flow rate of A was 300 mol/min.
(a) What are the PFR and CSTR volumes necessary to achieve 40 % conversion?
(b) Over what range of conversions would the CSTR and PFR reactor volumes be
identical?
(c) What is the maximum conversion that can be achieved in a 105-dm3 CSTR?
(d) What conversion can be achieved if a 72-dm3 PFR is followed in series by a 24dm3 CSTR?
(e) What conversion can be achieved if a 24- dm3 CSTR is followed in a series by a
72- dm3’ PFR?
Problem 3: Construct a complete stoichiometric table and calculate the
equilibrium conversion and concentration for each of the following reaction
(a) Liquid phase reaction
𝐴+𝐵 ↔𝐶
With CA0= CB0= 2mol/dm3 and Kc= 10 dm3/mol.
(b) The gas-phase reaction
𝐴 ↔ 3𝐵
Carried put in a plug flow reactor with no pressure drop. Pure A enter at
400 K and10 atm and Kc = 0.25 dm3/mol at the same temperature
Problem 4: The elementary irreversible organic liquid-phase reaction.
A + B →C
Is carried out adiabatically in a flow reactor. An equal molar feed-in A and B enter
at 27°C. And the volumetric flow rate is 2 dm3/s and Cao = 0.1 kmol/m3. Calculate
the PFR and CSTR volumes necessary to achieve 80% conversion. What are the
reasons for the differences?
Additional infonnation:
HA°(273) = -20 kcal/mol, HB°(273) = -15 kcal/mol, HC°(273) = -41 kcal/mol, CpA= CPb
= 15 cal/mol . K , K = 0.01 dm3/mol.s at300, CPc = 30 cal/mol.K , E = 10,000
cal/mol.
Problem 5: Reactant A (A → R, CA0 = 26 mol/m3 ) passes in steady flow through
four equal-size mixed flow reactors in series (total = 2 min). When steady-state is
achieved, the concentration of A is found to be 11, 5, 2, and 1 mol/m3 in the four
units. For this reaction, what must be plug so as to reduce CA from 26 to 1 mol/m3
what must be CSTR if a single CSTR is used?
Problem 6: Xylene can be produced from toluene as written schematically:
The values of G were determined at 700 K. What are the equilibrium
composition (including all xylene isomers) at 700 K and 1.0 atm pressure?
Problem 7: For the elementary solid-catalyzed liquid-phase reaction:
A ↔ B
Make a plot of equilibrium conversion as a function of temperature. When pure A
is fed to the reactor at a temperature of 300 what conversion could be achieved if
one cooler that had the capacity to cool the exit stream to 350 K were available?
Additional information: ∆𝐻𝐴0 (298 K) = -40,000 cal mol ∆𝐻𝐵0 (298 K.) = -60,000
cal/mol CPA= 50 cal. mol K CPB = 50 cal/mol • K. Ke , = 100,000 at 298 K.