CATALYSIS TASKS
TASK #1
In an experimental mixing reactor reactor filled with catalyst particles of 1.2
mm and a total mass of 10 g, the first-order reaction A  B takes place at a
pressure of 1 atm and a temperatura of 336ºC. The feed volumen velocity of
pure A is 4 cm3/s , achieving 80% conversión. The experimental reactor
operates in the absence of external and internal resistance. Based on the
experiments of the experimental reactor, we want to design a comercial
reactor that operates at 80% conversion. We choose between a fluidized bed
reactor (dp = 1mm) and a PBR reactor (dp = 1.5 cm), where the external
resistance on the catalyst side can be neglected. Use the same model
equation for the fluidized bed as for the stirred reactor. Choosing which of
the reactors provides the minimum need for a catalyst?
Other data: 𝜌𝑝 = 2000 𝑘𝑔/𝑚3 De = 1*10^6 m2/s
TASK #2
• In the PBR reactor, the reaction A  2B (k = 4 m^3/(m^3s)) takes
place in an aqueous solution, which is limited by internal difusión.
Calculare the mass of catalyst for 90% conversión if the molar Flow of
reactant A at the inlet FA0 = 1*10^4 mol/h.
• Other data:
𝜌𝑝 = 2000 𝑘𝑔/𝑚3 De = 4*10^8 m2/s, dp = 6 mm, cA0 = 1 mol/L.
TASK #3
• The heterogeneously catalyzed reaction A  B takes place in a porous
spherical catalyst with an initial concentration of A of 100 mol/m^3.
By how much is the velocity in the grain of the catalyst fue to internal
resistance lower than the reaction velocity on the Surface.
a) At the entrance to the reactor.
b) At the exit from the reactor at 80% conversion?
The reaction rate is written in the form
Other information:
De = 1*10^-6 m2/s, dp= 6mm
TASK #4
• The first-order reaction A  B takes place in a PBR reactor on a porous
catalyst at a atemperature of 1173 K and a pressure of 101.3 kPa. Pure
component A flows through a pipe of raiud 2,54 cm with a volumen Flow
rate of 1*10^6 m^3/s. Calculare the mass of catalyst for 99.8% conversión
of reactant A.
• Other data:
K= 2.34*10^-7 m3/gs
Gas : 1.53*10^-8 m^2/s DAB = 2*10^-8 m^2/s
Catalyst: De = 1.82*10^-8 m^2/s, 𝜌𝑝 = 2800 𝑘𝑔/𝑚3, 𝜀𝐵 = 0.5 , 𝑑𝑝 = 6𝑚𝑚
𝜀𝑝 ∗ 𝑑𝑗 = 0.357 ∗ 𝑅𝐸 −0,359
TASK #5
• The first-order reaction A  4B takes place in the gas pase in a PBR
reactor. The feed rate of pure reactant A is 2 kmol/h at a pressure of 3
bar and a temperatura of 160ºC. The reaction rate is written in the
form:
• Determine the volumen of the catalyst bed for a 60% conversión of
component A if the mass permeability coefficient kc = 2 m/h
Other information:
De = 6.56*10^-7 cm^2/s, 𝜌𝑝 = 2.24 𝑔/𝑐𝑚3, 𝜌𝐵 = 0.50 𝑔/𝑐𝑚3 dp=
1mm
TASK #6
• In the PBR reactor, the first-order reaction A B takes place. In the
case of using a spherical catalyst with a diameter of 9 mm, the
chemical reaction takes place under the high influence of internl
difusión, with a conversión of 63.2% achieved. How does increasing
the diameter of the catalyst grain to 18 mm affect the conversión?
TASK #7
• How large grains should we use to make the internal resistance
negligible?
• Other information:
TASK #8
• The PBR reactor is filled with porous catalyst particles 1.2 cm in
diameter. In the reactor at a temperatura of 336ºC and a pressure of
1 atm, the Elementary reaction A+B C+D ( k=0.01m^6/mol*kg*s)
takes place with a gas Flow rate of 1 m^3/s (1/3, 1/3B, 1/3l). What is
the mass of the catalyst to achieve 80% conversión?
• External material resistance is negligible.
• Other information:
De = 2*10^-6 m^2/s , 𝜌𝑝 = 2000 𝑘𝑔/𝑚3, dp = 1.2 cm
TASK #9
• The catalytic reaction of the first order is carried out in a mixing with
baskets. By changing the speed of rotation of the baskets, we have
achieved conditions where the external resistance can be neglected.
With grains of two different sizes, we determined the following values
of reaction rates:
• Determine the Thiele modulus and effectiveneness factor for both
grains.
TASK #10
• The speed of the first order catalytic reaction aB is studieed in the
absence of external material resistance at different sizes of spherical
catalyst grains. At the reactant concentration on the catalyst surface
Cas=0.025 mol/L, the following apparent reaction rate values were
measured:
• a) Determine the true rate of a chemical reaction and the reaction rate
constant.
• b) Determine 𝜃 𝑎𝑛𝑑 𝜂 for a grain with a diameter of 5 mm.
• c) Determine the value of the effective diffusivity De.
TASK #11
• The first-order catalytic reaction A  B is carried out at a temperatura
of 630ºC and a pressure of 1 bar in a PBR reactor with spherical
particles of diameter dp = 0.176 cm. At a feed rate of 0.2 mol/cm^3 ,
50% conversión was achieved. Calculate the value of the efficiency
factor 𝜂.
Other information:
De=8*10^-8 m^2/s
TASK #12
• Heterogeneous catalyzed reaction with reaction rate equation:
Is carried out in a PBR reactor in the presence of a solid catalyst with
spherical particles. Entrance the concentration of reactant A is 2.5
mol/L. At this concentration, the Thiele modulus is 8.0 for 80%
conversión of reactant A, determine the value of the quotient
TASK 13
• The reaction A  B was carried out in a differential packed bed catalyst
reactor at different temperaturas, molar flows and particle sizes. The
results are shown in the graph.
• a) Determines the operating conditions where the reaction rate is limited
by external material transport.
• b) Determine the operating conditions where the reaction rate is limited by
the chemical reaction.
• c) Determine the operating conditions where the reaction rate is limited by
internal difussion.
• d) Calculate the effiency factor for a temperatura of 400 K and a catalyst
particle diameter of 0.8 cm.
TASK #14
• The heterogeneously catalyzed irreversible dimerization reaction
2 A A2 was studied in a basket reactor at a rotating speed where
the external resistance can be neglected. Each of the 4 baskets
contained 40 g of catalyst. Pure reactant A was fed into the reactor at
a pressure of 8.2 atm. At a temperature of 227 ºC,
• the following experiments were performed at a temperature of
237ºC,
• the following experiments was performed FT0 = 9 mol/min. And yA =
0.097. The reaction is limited by internal difussion.
• A) Apparent order of the reaction and the apparent activation energy.
• B) Determine the correct order of the reaction and the correct
activation energy.
Fraction of A at oulet, yA
TASK #15
• The exothermic reaction A + B  C was performed with two different
catalyst particle sizes. The reaction took place under conditions where the
externla resistance on the catalyst side can be neglected. The following
global reaction rate data were obtained at a different temperatures.
• A) Calculate the activation energy
• B) Calculate the efficiency factor at each of the temperaturas for particles
with a diameter of 8 mm.
TASK #16
• The exothermic reaction A  B (10% A, 90% I) takes place in a PBR reactor and is limited by external mass transport, internal
difusión and Surface reaction, for which we can write:
• At a certain point in the reactor, the pressure and temperatura in the main stream are 0.05 bar and 500 K, the efficiency is 0.08,
and the mass Flow per empty cross-section of the reactor is 0.8 kg/m^2s. At this point in the reactor,
• A) Calculate the global reaction rate at this point
• B) Calculate the external concentration gradient
• C) Calculate the temperatura gradient.
• Other information:
• Gas:
• Catalyst:
• Reaction:
where:
TASK #17
• The endothermic catalytic reaction AB takes place in a differential PBR reactor and is limited by
external mass transport, internal difusión and Surface reaction, for which we can write:
• A reaction mixture of 50% A and 50% I enters the reactor at a total pressure of 1 bar and a
temperature of 750 K. Mass Flow (G) to empty. Calculate the global gradient, if the conversion
reaction rate, efficiency factor, external concentration and temperature cross section of the
reactor is 1 kg/m^2s differential PBR reactor is 3.6 %.
• Other data:
• Gas:
• Catalyst:
• Reaction: