J
FEATURE REP()RT
Keepthe catalyst in mind
from the beginning
CATALYTIC
REACTOR
DESIGN
M
ost major processes in the chemical
process industries are built around
heterogeneous chemical reactions. A solid
catalyst is an integral part of almost all
these operations. In new-construction or
retrofit projects for such plants, process engineers must
design and specify not only the reactors but also the catalysts.
Independent design of the two, without concern for
how they will mesh, can mean a more costly design, a low
production rate and more-frequent shutdowns. It may
even cause the catalyst to fail.
Consider, for instance, this debacle at a methanol
plant. A carbon-steel pipe had been installed at the en,trance to the methanol reactor. High-pressure carbon
monoxide in the feed stream reacted with the steel to produce iron carbonyls, which poisoned the catalyst [171.
Remedying the situation cost several million dollars.
With the hope of avoiding such situations, we first
summarize the principles of catalyst and reactor design,
with emphasis on maintaining interdependence between
the two activities. Then we apply the principles to industrial reactors.
The focus is solely on heterogeneous catalysis, in
which the catalyst (virtually always in solid form) is not
in the same phase as the process stream. Even with this
limitation, the technology is far too detailed for full presentation here. Instead, our aim is to enable readers to
keep the big picture in mind whenever getting immersed
in the specifics of a project.
Calvin H. Bartholomew and William C. Hecker
BrighamYoung University
70
CHEMICAL ENGlNEERlNGiJUNE 1994
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Part 1
1
t‘
Catalyst design
eterogeneous catalysts come in a
wide variety of forms. Most are
spheres, tablets, rings, pellets of
various shapes, or monolithic honeycomb structures. Generally,this particle
or structure consists of an active catalytic species impregnated into or deposited onto a nominally inert support.
Design involves both the active catalyst and the support. It consists essentially of choosing the right type and
form of catalyst for a given situation,
then specifying its size, porosity, catalytic-species distribution and other
properties.
This design procedure requires the
engineer to deal with the catalytic functions, chemical and physical properties,
and mechanical and flow properties of
the catalyst. These three groupings are
highly interrelated.
For instance, catalytic functions include activity, selectivity for desired
products, and stability against deactivation; each of these depends on the
chemical and physical makeup of the
catalyst. Mechanical properties, including particle strength and attrition resistance, depend on the chemical stability and microstructure of the solid and
the presence of binders. And flow properties, such as flow distribution and
pressure drop, depend on particle
shape and size.
The interrelation often generates a
need for compromises. For instance,
mechanical strength decreases with increasing porosity 151, especially above a
porosity of 50%, whereas activity at
high conversions (entailing conditions
where pore diffusional resistance is
high) rises with increasing porosity. Accordingly, the degree of porosity must
be a compromise between high activity
and high mechanical strength.
Furthermore, moderately active catalysts tend to be chemically more stable than those of high activity. And
pressure drop through the system is
lowest for large catalyst particles, at
the expense of higher pore diffusional
resistance and hence lower activity.
An imaginative engineer will be alert
for new approaches or materials that at
least partially circumvent the need for
compromises. For instance, a compara-
H
Amencan Oil Co
tively new catalyst composed of a ceramic honeycomb monolith with a thin
catalyst wash-coat inside its channels
provides both low pressure drop and
low pore diffusional resistance, i.e.,
high activity.
Eight steps: A stepwise procedure for
catalyst design follows. The appropriate interweaving of this procedure with
reactor design is explained beginning
on the next page.
(1) Spell out the reactants, products
and operating conditions for the
process
(2)Identify and list all possible chemical
reactions (includingundesired ones)and
categorize them according to the type of
bond changes. Examples of reactions include dehydrogenation, hydrogenation,
oxidation, carbon monoxide insertion,
dehydration, and group addition
(3) Assess the feasibility and energetics
of each reaction in Step 2, by calculating its enthalpy change, free-energy
change and other relevant thermodynamic parameters
(4)For the reactions that Step 3 shows
to be significant, visualize the actual
molecular changes, the elementary reactions on the catalyst surface, and the
active intermediates. From this, predict the important reaction paths
(5) Determine what kinds of catalytic
functions or sites (for example, adsorptive, desorptive, hydrogenative, acidic)
will be necessary. For instance, lowtemperature methane combustion calls
for catalytic sites that dissociatively
chemisorb oxygen and methane but
easily desorb water
(6) Seek catalyst materials that offer
the appropriate catalytic functions
(e.g.,platinum or nickcl for hydrogcnntion, and zeolites for cracking),the necessary thermal stability, and resistance
to poisoning or fouling. Look also for a
stable, compatible support material, as
well as promoters to enhance activity
or stability
(7) Specify the catalyst microstructure
in terms of crystallinity, surface area,
porosity and similar parameters that
govern catalyst strength and attrition
resistance. Also, specify catalyst particle size and shape, and choose binders
to give the particle strength and attrition resistance.
In this step, keep in mind the importance of minimizing pressure drop.
Apart from the decrease with increasing catalyst-particle size, the pressure
drop per unit height of catalyst bed can
be decreased by factors as high as ten
through careful choice of monoliths or
uniquely lobed or star-shaped pellets.
At a constant particle diameter, pressure drop increases in the following
order: lobes, rings, extrudates, tablets,
spheres
(8) In most cases, Steps 1-7 generate
several potential catalyst candidates.
Test these experimentally for activity,
selectivity and stability
Databases can be valuable at many
points in this eight-step process [lo].In
Steps 3-6, for instance, computerized
data banks containing thermodynamic
data, reaction mechanisms, surfacechemistry data, and catalyst properties
greatly speed the selection process.
Reactor design
Design of a reactor combines material
balances, energy balances and kinetic
rate expressions to come up with the
optimum reaction conditions and type
and size of reactor (or reactors) for a
given process. “Optimum” usually
means the minimum vessel volume for
a single-reactionprocess, or the best selectivity or product distribution for a
process with multiple (parallel or series) reactions.
Material balance: Sometimes called
the species-continuity equation or the
reactor-performance equation, this
tells how any given reaction species is
distributed in space and time. The material balance presupposes a particular
reactor type.
Detailed discussion of material balances (and of energy balances and Enetic rate expressions) is beyond the
scope of this article. A material balance
may be as complicated as Equation 1in
Table 1, which describes a transient,
two-dimensional reactor in which axial
dispersion is important. Or, it may be
as simple as the performance equation
for the continuous stirred-tank reactor
(CSTR), Equation 2, derived from
Equation 1 by assuming steady-state,
uniform concentration in the radial direction and no axial dispersion. For a
typical one-dimensional reactor, the
material balance predicts conversion as
CHEMICAL ENGINEERING/JUNE 1994
71
TABLE 1.
THREE KEY RELATIONSHIPS FOR REACTOR DESIGN
1. Material Balance
- Reactor Performance Equation
3. Rate Expression
-
Rate Equation
no mass transfer influence :
2. Energy Balance
-
Conservation of Energy
17 = 1 j D-(strong
eff
L k“‘
a function of the distance z into the re- exothermicityand heat losses to the surroundingsare all important. Conversely,
actor and of the reaction rate ( -rA).
In principle, there is one material- it may be as simple as Equation 4,which
balance equation for each species in the applies to a one-dimensional adiabatic
reactor. For a typisystem. However,
cal
one-dimenfor a single reaction
NOMENCLATURE
sional
reactor
this
the species are all
A Aconstant
relationship
pretied together by the
Ci Concentration of species i
dicts temperature
. stoichiometric relaC, Heat capacity at constant
as a functionof distionship (e.g., A t B
pressure
tance z and reac= C + D), and thus,
DAB Diffusivity of A into B
tion rate -rA.
only one balance is
E
Energy of activation
Since conversion
needed to fully deFA,, Inlet molar flowrate of A
(XA)is also a funcscribe the system.
AH, Heat of reaction
tion of these two
k
Thermal conductivity (Eq.3);
For multiple reacrate constant (Eq. 6,8)
variables, under
tions, there must
Ki Constants
some
circumbe one additional
L
Characteristic length of catalyst stances temperamass balance equapellet
ture becomes a
tion for each addiq Heatrates
unique function of
tional stoichiometr
Radial distance
conversion,
as
ric reaction that
Rate of generation of A
r,
shown in Equadescribes the react
Time
tion 4 [121.
tion network.
T
Temperature
The energy balEnergy balance:
v, Radial velocity
ances just disThis spells out how
v, Axial velocity
clxssed describe
temperature varies
V Volume
macroscopic temin space and time
X , Fractional conversion of A
perature
gradithroughout the rez
Axial distance
ents
across
the
actor. A description
7 Effectiveness factor
length
and
width
of the temperature
p$ Term accounting for viscous
of the reactor. One
field is important,
dissipation
must sometimes
because the reacp . Density
carry out addition rate is in most
tional energy balinstances a strong
ances on singlecatalyst pellets, to deterfunction of the temperature.
The energy balance may be as compli- mine temperature gradients between
cated as Equation 3 in Table 1,which de- the gas phase and the catalyst surfaceor
scribes the temperature profile in a tran- within the pellet or both.
sient, two-dimensionalreactor in which Kinetic rate expression:This describes
axial dispersion, viscous dissipation, how the reaction rate of each species deI
I
72
CHEMICAL ENGINEERING/JUNE 1994
pore resistance, 1st order)
(8)
pends on concentrations, temperature,
and catalyst properties. The rate expressioncanbevery complex;for instance,see
Equation 5 in Table 1,which is for a reversible, temperature-dependent Langmuir-Hinshelwood-type reaction (see
Folger, H.S., “Elements of Chemical Reaction Engineering,” 2nd ed., Prentice
Hall, 1992).For a much less complex example, see Equation 6, covering simple
first-order irreversible reactions. If the
system has a deactivating catalyst, an
equation for activity as a fundion oftime
should also be included.
Whenever internal or external masstransfer influences affect the reaction
rate, it can be adjusted by multiplying
the intrinsic rate expression by an effectiveness factor as shown in Equations 7 and 8 for internal influence. The
resulting “global” or “observed” rate
should then be used in material and energy balances.
For systems with strong internalpore-diffusion resistances (quite commor, ir, industrial catalytic-reactw systems), the effectiveness factor is a
function of catalyst diameter and catalyst pore sizes. The relationship is expressed via the effective diffusivity,
Deff;see Equation 8. This is one of the
key links between reactor design and
catalyst design, as the physical and
chemical properties of the catalyst influence the reactor design directly by
affecting the rate expression
Catalytic reactor design
As already emphasized, proper design
of the catalytic reactor must be a care-
,
fi
fully arranged marriage of catalyst and
reactor. This interdependence shows
up in several ways.
For example, a more-active catalyst
enables operation at milder conditions
of temperature and pressure; moreover
it minimizes the required reactor volume and cost. A catalyst whose activity
is very stable (with a life on the order of
months or years) can be matched with a
relatively lower-cost tubular bed reactor rather than a more expensive fluid
bed system, because it need not be replaced ofien. High-pressure conditions
are likely to require selection of a robust packed-bed reactor and a catalyst
in monolith or large-pellet form to minimize pressure drop.
A practical sequence to achieve the
optimal combination of catalyst and reactor is as follows:
1. For various candidate reactor
types that seem promising, use the previously outlined reactor-design relationships to specify the reactor size (including the amount of catalyst needed),
the concentrztioii aid temperature
profiles, the quantity of heat that must
be added or removed, and the rate of
deactivation
2. Choose among the candidates,
using these criteria:
(a) Minimize the volume of catalyst,
and therefore reactor size, required.
For instance, in the case of an irreversible first-order reaction, a tubular
reactor requires a lesser volume than
does either a slurry reactor or a fluidbed reactor
(b) Provide for eficient heat transfer
when dealing with strongly exo- or en-
FEATURE REPORT
dothermic reactions. Slurry or fluid-bed
reactors are attractive in this regard
(c) Also for strongly exo- or endothermic reactors, consider reactors or at
least catalyst trays in series, with interstage heating or cooling [12]
(d) In situations in which the catalyst
becomes deactivated rapidly (in seconds to hours), provide for rapid, convenient regeneration
3. Choose the catalyst type and form
that will:
(a) Maximize activity, selectivity and
stability
(b) Minimize pressure drop and maximize access of reactants to the porous
catalyst interior. Lobed extrudates are
attractive for this; so are monoliths
wash-coated with catalyst [B, 111.
(c) Be compatible with the reactordesign needs; for instance, with high
thermal conductivity for highly endothermic or exothermic reactions, and
with sufficient mechanical strength so
that catalyst at the bottom of the reactor can withstand the full weight of material above it
4.Choose the reactor-catalyst combinations that will minimize capital cost
and overall production costs. In this
connection,be aware that the price of a
catalyst is usually a relatively minor
consideration in comparison to its activity, selectivity,and stability
0
n order to use these design princiSimplicity, giving low cost and miniples effectively, the engineer must mal maintenance
Allowance for greater variation in opbe familiar with the types of reactors
actually available in practice. These erating conditions and contact times,
can be divided into two general classes, and hence in conversion
High ratio a€ cata!yst to rea.cta.nnrs,
fixcd-bcd am! hidizec! cr slurry bed.
giving longer residence time and thus
Fixed vs. fluid
more-complete reaction
In fixed-bed reactors, the catalyst re- *Minimal wear on catalyst and equipmains essentially stationary until it is ment
to be reactivated or discarded. It may,
Practical operation at very high presfor instance, be confined within the sures
tubes of a tubular reactor, or it may be Conversely, fluidized-bed and slurry
placed on trays.
reactors offer these advantages over
The advantages of fixed-bed reactors, fixed-bed versions:
especially in comparison with fluidized
Easier catalyst regeneration and reor slurry-bed reactors, include:
placement
Rapid mixing, which facilitates efiApproximation of ideal plug-flow
operation, and thus high conversion ef- cient heat transfer and, thus, isothermal operation
(Continues)
ficiency
CHEMICAL ENGINEERING/JUNE 1994
73
-~
FEATURE REPORT
Low pore-diffusional resistance, due also influence the choice of reactor. For relate mainly to the reactor type choto the small size of catalyst particles example, catalysts used in fixed beds typ- sen; others concern the nature of the
typically used
ically must offer a crush strength of at catalyst or the process. Many are exTemperature control in fixed-bed re- least 3 kdparticle (or an axial crush plained best by considering specific exactors can be improved, at additional strength of 50-80 kg/cm2).Otherwise the amples.
cost, through such measures as inter- pellets at the bottomofthereactor may be Fixed-bed reactors: In these, it is parstage cooling or heating. Judicious use crushed to fines, causing unacceptably ticularly important to maximize cataof competing reactions or partial poi- high pressure drop across the reactor.
lyst strength and porosity, minimize
soning of the catapressure drop, minlyst can serve the
imize pore diffusame purpose.
sional resistance,
1. Catalyst deactivation behavior;
3. Catalyst strength and attrition reFor instance, in
and maximize cataregeneration policy
sistance: Fixed-bed catalysts must lyst life. As already
the oxidative dea. Fixed beds are favored if the
be strong enough to avoid being
hydrogenation of
noted, several of
life of the catalyst is longer than
crushed
at reactor bottom. Severe
methanol to for
these features are
about 3 mo
attrition rules out use in a fluid bed
maldehyde, the reobtained at the exb. Fluidized or slurry beds are
action with oxygen
pense of each other.
favored in process situations that
4. Process economics:
(CH30H + 0.5 0, .=
Consider pellets,
involve rapid deactivation and the
a. Capital cost depends on the
HCHO + H,O) is
need to regenerate the catalyst
for example. Becomplexity of design, cost of
highly exothermic
materials, reactor fabrication,
cause
pressure
and catalyst cost
(-156
kJ/mol), 2. Reaction conditions: Fixed beds
drop decreases and
are favored for high pressures;
b. Operating cost depends
whereas the direct
crush strength influid or slurry beds are favored
mainly on pressure drop,
dehydrogenation
creases with infor strongly exo- or endothermic
maintenance, regeneration
(CH30H= HCHO +
creasing particle
reactions.
costs and heat-transfer duty
H,) is quite endiameter while the
dcthermic (85 kJ/
pore diffusional remole).Accordingly, the reaction temperIn fluidized or slurry bed reactors, at- sistance increases, it makes sense to
ature of the system can be regulated by trition of just a few percent of the total choose lobes or rings, so as to obtain
controlling the oxygen concentration catalyst charge per day leads to uneco- lower pressure drop per given particle
and the oxygen-to-steamratio.
nomical loss of catalyst. And in a slurry diameter. Thus, three- and four-lobed
reactor, it upsets the catalyst separa- particles are used in hydrodesulfurizaMaking the choice
tion process.
tion to minimize both pressure drop
Long catalyst life (greater than 3 mo)
Capital cost is affected by complexity and pore diffusional resistance.
favors fixed bed reactors. On the other of the design. For example, in the
In low-temperature methanation or
hand, a rapidly deactivating catalyst highly exothermic Fischer-Tropsch Fischer-Tropsch synthesis, high mesothat needs frequent replacement or re- syntheses (involving production of liq- porosity is needed to obtain extensive
generation mandates the use of a flu- uid hydrocarbons from carbon monox- metal surface area, and high macropidized or slurry bed reactor, because in ide and hydrogen), a single liquid- orosity is needed for reactant access
such a system the deactivated catalyst phase
slurry reactor involves while minimizing pore diffusional recan be removed and fresh catalyst substantially less material and fabrica- sistance. But catalyst strength is not a
added during operation.
tion costs than a fixed bed reactor con- big issue, because reaction conditions
The next priority in the selec taining hundreds of small diameter, are mild and the catalyst beds are not
process is to consider reaction condi- catalyst filled tubes [MI. Conversely, high. Accordingly these catalysts are
tions, especially catalyst temperature. fluidized beds can incur high capital typically supported on extruded pellets
Been,*"-.
,ct+ puur tLfi-L +
auuc
conduct:i;costs for the equipiileilt associated with Cwab
ait: ~ u i i ~ p u s a ~f
i : ii high-s&iceity of a typical ceramic-supportedsolid fluidization.
area gamma-alumina of moderate
catalyst, a large fixed bed reactor more
Operating cost depends greatly on crush strength and relatively moderate
than a few inches in diameter behaves the pressure drop through the reactor. resistance to hydrothermal sintering.
essentially adiabatically, so control of This dependence also affects capital
On the other hand, nickel catalysts
reaction temperature is not possible for cost, because it determines the size of used in high temperature steam rea highly exo- or endothermic reaction. the process compressor or pump. forming must be strong and hydrotherAny resultant overheating can degrade Among the other significant determi- mally stable. Accordingly, relatively
the catalyst or lower its selectivity. On nants of operating cost are mainte- large nickel crystallites are supported
the other hand, the well-mixed behav- nance, catalyst regeneration and heat- on pressed pellets or rings consisting of
ior of fluidized and slurry reactors facil- transfer duty.
a low-surface-area calcium or magneitates efficient convective heat transfer
sium aluminate or alpha alumina, all
and temperature control, as has al- Some pointers
three of these offering high strength
ready been noted.
The engineer should also keep the fol- and high hydrothermal stability.
Catalyst strength and attrition may lowing practical points in mind. Some Monoliths: For catalytic processes of
U I l,I G
74
-fir\..
Wl.a1114!
CHEMICAL ENGINEERING/JUNE 1994
^I^
^^__^^^
!
Part 1
,
high gas throughput or space velocity,
monoliths can be employed to great advantage over pellets because they incur
a lower pressure drop. Both the pressure drop and the geometrical surface
area (GSA) of the monoliths decrease
with an increase in the monolith channel diameter.
In mass-transfer-controlled reactions, such as CO oxidation on Pt-alumina in automotive converters, GSA
should be maximized; accordingly,
there must be a trade-off between low
AP and high GSA. Because of the inherently low AP of thin-walled ceramic and
metal monoliths, it is possible to design
converters for high GSA (40 cm2/cm3)
with a fine mesh size (93 squares/cm2)
while keeping AP adequately low for efficient auto exhaust operation. To further enhance the access of reactants to
metal crystallites inside the catalyst
pores (in other words, minimize the
pore diffusional resistance or maximize
the catalyst effectiveness), the catalyst
is wash-coated in a thin layer of about
0.01 mm thickness inside the monolith
channels.
By contrast, monoliths used in selective catalytic reduction (SCR) of NO in
power plants on the hot side of the
boiler are designed with a large mesh
size and low GSA (2-4 squares/cm2and
7-14 cm2/cm3),to prevent plugging with
fly ash. They also have thick catalystcontaining walls to prevent loss of activity due to erosion of the catalyst by
fly ash particulates. For this application, wash-coated catalysts would
quickly lose activity as the catalyst
eroded away.
Fluidized or slurry bed reactors:. In
these, the particle size is generally
small (in the range of 30-200 micrometerra), ani: gwei-iied by the operzting
conditions of the process necessary to
maintain an expanded, fluid bed. With
these reactors, the catalyst design focuses on maximizing activity, selectivity, and resistance to attrition and
spalling.
This resistance is achieved by the appropriate combination of catalyst
porosity, support-material type and
particle size, and type of binder (e.g.,
silica or carbon). In developing this
combination, the engineer must design
not only for high strength but also to
avoid any phase changes or reactions
(e.g. carbiding or hydration) that in
themselves would bring about spalling
or particle disintegration.
Catalyst distribution in particles:
As noted near the beginning of this article, a catalyst particle consists of an
active catalytic species and an inert
support. Activity losses due to transport limitations and deactivation can
be minimized by careful specification
of the catalytic-species distribution
throughout the support.
According to Becker and Wei [22],the
optimum catalyst distribution depends
on relative rates of reaction and deacti-
vation. For instance, in the case of fast
reaction and fast poisoning, the optimum distribution (or catalyst profile) is
an active band between a thin inert
outer shell and inert center. This has
been called the middle-egg-white profile. For fast reaction and slow poisoning, the optimum profile is a thin outer
coating or shell of active catalyst at the
exterior surface, called the eggshell
profile. The predictions of Becker and
Wei have been borne’ out experimentally in several catalytic processes [23,
24,251.
I
Edited by Nicholas P. Chopey
References
1.“Catalysts Looks to the Future,” National Research Council Panel, National Academy
Press, Washington, D.C., 1992.
2. Hegedus, L.L. “Catalytic Technologies for Air
Pollution Control,” U.S. Russia Workshop on
Environmental Catalysis, Wilmington, Del.,
Jan. 14-16,1994,
3. Dowden, D.A. Schenll, C.R., and Walker, G.T.,
“The Design of Complex Catalysts,” Fourth International Congress on Catalysis, ed. Hightower, J.W., Rice University, Houston, 1968, p.
1120.
4. Trimm, D.L., “Design of Industrial Catalysts,”
Chemical Engineering Monographs, 11, Elsevier, 1980.
5. Sleight, A.W., and Chowdhry, U., Catalyst Design and Selection, in Leach, B.E., ed, “Applied
Industrial Catalysis,” Academic Press, 1983,
Vol. 2, Chapter 1,pp. 1-25.
6. Hegedus, L.L. (ed.), “Catalyst Design,” Wiley,
1984.
7. Hegedus, L.L. et al, “Catalyst Design, Progress
and Perspectives,” Wiley, 1987.
8. Richardson, J.T., “Principles of Catalyst Development,” Plenum Press, 1989.
9. Inui, T., ed, “Successful Design of Catalysis,”
Stud. Surf. Sei. Catal., 44, Elsevier, 1989.
10. Becker, E.R., and Pereira, C.J., eds, “Computer-Aided Design of Catalysts,” Marcel
Dekker, 1993.
11.Satterfield, C.N., “Heterogeneous Catalysis in
Industrial Practice,” 2nd ed, McGraw-Hill,
1991, Chapter 4.
12. Levenspiel, O., “Chemical Reaction Engineering,” 2nd ed, Wiley, 1972.
13. Smith, J.M., “Chemical Kinetics,” 3rd ed, McGraw-Hill, 1981.
14. Lee, H.H., “Heterogeneous Reactor Design,”
Buttenvorth, 1985.
15. Froment, G.F., and Bischoff, K.B., “Chemical
Reactor Analysis and Design,” 2nd ed, Wiley,
1990.
16. Fogler, H.S., “Elements of Chemical Reaction
Engineering,” 2nd ed, Prentice Hall, 1992.
17. Collier, C.H., “Catalysis in Practice” Reinhold,
1957.
18.Bartholomew, C.H., in “New Trends in CO Activation,” Studies in Surface Sei. and Catalysis, 64, ed. L. Guczi, Elsevier, 1991.
19. “Reactor Technology,” Kirk-Othmer Encyclopedia of Chemical Technology, 3rd ed., Vol.. 19,
Wiley, 1982, pp. 880-914.
20. Boer, F.B., et al, Chem. Tech., 312, May 1990.
21. Bhatt, B.L.,et al, “Liquid Phase Fischer-Tropsch Synthesis in a Bubble Column,” presented
at the DOE Liquefaction Contractors’ Review
Conference, Pittsburgh, Pa, Sept. 22-24, 1992.
22. Becker, E.R., and Wei, J., J. Catal,. 46, 365,
372 (1977).
23. Hegedus, L.L., and McCabe, R.W., ‘‘Catalyst
Poisoning,” Marcel Dekker, 1984.
24. Oh, S.H., Catalyst Converter Modeling for Automotive Emission Control, in Becker, E.R.
and Pereira, C.J., eds, “Computer-Aided Design of Catalysts,” Chap. 8, Marcel Dekker,
1993.
25. Iglesia, E., et al, Reaction-Transport Selectivity Models and the Design of Fischer-Tropsch
Catalysts, in Becker, E.R., and Pereira, C.J.,
op. at., Chap 7.
The authors
Calvin H. Bartholomew,
Jr., is Professor of Chemical
Engneermg at Brigham
Young U ( B W ) , and head of
the B W Catalysis Laboratory. He was previously a Senior Chemical Engmeer for
Corning Corp., Corning, N Y
He has conducted research
for 25 years in catalysis and
combustion, with emphasis on
activitv-structure
relationships, deactivation, chemisorption, and catalysis
for syngas conversion and for selective reduction
of NOx. Bartholomew has written two books and
over 100 papers, and consulted with over 20
firms. He received the American Chemical Soc.’s
Utah Award in 1991. He holds a B.S. in chemical
engineering from BYU, as well as a Ph.D. from
StanFord U.
William C. Hecker is an Associate Professor of Chemical
Engineering at BYU, Associate Head of the Catalysis Laboratory and head of the Char
Oxidation Group. Before joining BYU, he was with
Chevron Research Corp. and
Dow Chemical Co. He has
nearly 30 publications and 3
patents, and has been presenter or eo-presenter of 92 technical papers. Research interests include kinetics,
heterogeneous catalysis, coal char Oxidation, NO
reduction, auto emissions control, and infrared
spectroscopy of surfaces. In 1986, he received an
AIChE national award as outstanding studentchapter counselor. He holds B.S. and M.S. degrees from BYU and a Ph.D. from the U. of California at Berkeley, all in chemical engineering.
CHEMICAL ENGINEERING/JUNE 1994
75
FEATURE REPORT
FIGURE 1. The heart of any static-mixing reactor, such as the one being assembled here, is its array of stationary guiding elements within the vessel
76
CHEMICAL ENGINEERINGNUNE 1994