1. Review Chapters (1 – 6)
CHPE550: Catalysis and Catalytic Processes
Lecturer: Dr Hazim Fadhil Abbas Office : 5D-40, College of Engineering

2. Introduction to reaction engineering Reaction Rate
The reaction rate is the rate at which a species looses its chemical identity per unit volume.
The rate of a reaction can be expressed as the rate of disappearance of a reactant or as the rate of appearance of a product.
Consider species A: A  B
-rA = the rate of a disappearance of species A per unit volume
rB = the rate of formation of species B per unit volume

3. Reactor Mole Balance Summary
Differential
Algebraic
Integral
Batch
CSTR
PFR (Plug flow reactor)
PBR (Packed bed reactor)

4. Reactor Sizing CSTR
Given – rA as a function of conversion, – rA=f(X), one can size any type of reactor. We do this by constructing a Levenspiel plot.
0.2
0.4
0.6
0.8 10 20 30 40 50
Here we plot either
as a function of X. X
XEXIT
For vs. X, the
volume of a CSTR is:

5. Space Time & Space Velocity
Space time, τ, is obtained by dividing reactor volume (V) by the volumetric flow rate entering the reactor (vo):
The space time is the time necessary to process one reactor volume of fluid based on entrance conditions.
Space velocity, SV, is obtained by dividing the volumetric flow rate entering the reactor by the reactor volume :
The SV is the reciprocal of the space time.

6. Rate Law Basics k is given by the Arrhenius Equation: Where:
E = activation energy (cal/mol)
R = gas constant (cal/mol*K)
T = temperature (K)
A = frequency factor (units of A, and k, depend on overall reaction order)

7. Batch Stoichiometric Table
Species
Symbols
Initial
Change
Remaining A
NA0
-NA0X
NA=NA0(1–X) B
NB0=NA0ΘB
-(b/a)NA0X
NB=NA0(ΘB –(b/a)X) C
NC0=NA0ΘC
(c/a)NA0X
NC=NA0(ΘC+(c/a)X) D
ND0=NA0ΘD
(d/a)NA0X
ND=NA0(ΘD+(d/a)X)
Inert I
NI=NA0ΘI
NI = NA0ΘI
NT0
NT=NT0+δNA0X

9. Algorithm : Pressure Drop in a Packed Bed Reactor
Analyze the following second order gas phase reaction that occurs isothermally in a PBR: 
A   B
Mole Balance:
Must use the differential form of the mole balance to separate variables (remember that FA = FAO * X):
Rate Law:
Second order in A and irreversible:

10. Multiple Reactions and Pressure Drop
In terms of conversion: ε

11. MEMBRANE REACTORS (MR’s)
Fogler page and
Membrane Reactors are used to :
(1) increase conversion when reaction thermodynamically limited
(2) increase selectivity when multiple reactions are occurring

12. (1) Thermodynamically limited reactions
These are reactions where equilibrium lies far to the left
and therefore there is little conversion
If reaction is exothermic, increasing the temperature will
drive reaction further to the left ; decreasing the temp.
results in very slow reaction rate .
- therefore very little conversion
If reaction endothermic, increasing the temp moves
reaction to right therefore favouring higher conversion.
However for many reactions increasing the temp can
destroy the catalyst.

13. STRUCTURE OF MEMBRANE REACTOR
Membrane can either be barrier to certain components
while permeable to others, or
contain active reactive sites and may be a catalyst in itself.
Therefore membrane can either be inert or catalytic
Achieve very high conversions by allowing one of reaction
products diffuse out (eg. Hydrogen is small enough to diffuse
through pores) , therefore high conversion, and
reaction proceeds to completion

14. the mole balance on hydrogen must be modified because
For the reaction:
the mole balance on hydrogen must be modified because
hydrogen leaves through both sides of the reactor and at the
end of the reactor.Therefore the mole balance on hydrogen
becomes:
where Rb is the molar rate of B leaving the reactor
kc is the mass transfer coefficient

15. (2) Enhancing Selectivity
Selectivity can be achieved by controlling the feed of
species through the reactor and through the membrane.
Can enhance selectivity by keeping one reactant low.
Can keep concentration low by feeding through sides of
membrane

17. Selectivity and Yield Instantaneous Overall Selectivity: Yield:
Example:
desired product ,
undesired product,

18. Finding the Rate Law Deferential Method Integral Method
Initial Rate Method
Half Life Method
Least Square Method