REACTOR DESIGN Flashcards
Rate of chemical reaction is independent of the concentration of reactants for
(a) zero order reaction
(b) third order reaction
(c) consecutive reaction
(d) none of these
zero order reaction
Which of the following is not a unit of reaction rate?
(a) moles formed/(surface of catalyst) (time)
(b) moles formed/(volume of reactor) (time)
(c) mole formed/(volume of catalyst) (time)
(d) none of these
none of these
If “n” is the order of reaction then unit of rate constant is
(a) 1/
(time) (concentration)n-1
(b) (time)-1(concentration)n-1
(c) (time)n-1 (concentration)
(d) none of these
(a) 1/
(time) (concentration)n-1
Which of the following is a controlling factor in very fast heterogeneous reaction?
(a) heat and mass transfer effects
(b) pressure
(c) temperature
(d) composition of reactant
heat and mass transfer effects
Rate determining step in a reaction consisting of a number of step in series is the
(a) fastest step
(b) slowed step
(c) intermediate step
(d) data insufficient; can’t be predict
slowed step
Variables affecting the rate of homogeneous reactions are
(a) pressure and temperature only
(b) temperature and composition only
(c) pressure and composition only
(d) pressure, temperature and composition
pressure, temperature and composition
Chemical kinetics can predict the
(a) rate of reaction
(b) feasibility of reaction
(c) both (a) and (b)
(d) none of these
rate of reaction
Velocity of a chemical reaction
(a) decreases with increase in temperature
(b) increases with increase of pressure of reactant for all reactions
(c) decreases with increase of reactant concentration
(d) none of these
none of these
Sum of the powers of the concentration terms in the rate equation is called the
(a) order of the reaction
(b) overall order of the reaction
(c) molecularity of the reaction
(d) none of these
overall order of the reaction
Molecularity of a reaction
(a) is always equal to the overall order of reaction
(b) may not be equal to the order of reaction
(c) can’t have a fractional value
(d) both (b) and (c)
both (b) and (c)
Inversion of cane sugar is an example of
(a) unimolecular reaction with first order
(b) bimolecular reaction with second order
(c) bimolecular reaction with first order
(d) unimolecular reaction with second order
bimolecular reaction with first order
Concentration of the limiting reactant (with initial concentration of a moles/liter) after time t is (a-x).Then t for a first order reaction is given by
(a) kt = ln (a/a-x)
(b) kt = x/a(a-x)
(c) kt = ln (a-x/a)
(d) k.t = a (a-x)/x
kt = ln (a/a-x)
Half life period of a chemical reaction is
(a) the time required to reduce the concentration of the reacting substance to half its initial value
(b) half of the space time of a reaction
(c) half of the residence time of a reaction
(d) none of these
the time required to reduce the concentration of the reacting substance to half its initial value
Fill up the blanks:
Half-life period for a first order reaction is………………….. the initial concentration of the reactant
(a) directly proportional to
(b) inversely proportional to
(c) independent of
(d) none of these
independent of
Fill up the blanks from among the alternatives given below: In a first order reaction the time required to reduce the concentration of reactant from 1 mole/liter to 0.5 mole/liter will be …………. that required to reduce it from 10 moles/liter to 5 moles/liter in the same volume
(a) more than
(b) less than
(c) same as
(d) data insufficient; can’t be predicted
same as
Specific rate constant for a second order reaction
(a) is independent of temperature
(b) varies with temperature
(c) depends on the nature of the reactants
(d) both (b) and (c)
both (b) and (c)
The reaction in which rate equation corresponds to a stoichiometric equation is called
(a) elementary reaction
(b) non-elementary reaction
(c) parallel reaction
(d) autokinetic reaction
elementary reaction
Equilibrium of a chemical reaction as viewed by kinetics is a
(a) dynamic steady state
(b) static steady state
(c) dynamic unsteady state
(d) none of these
dynamic steady state
For a zero order reaction, concentration of product increases with
(a) increase of reaction time
(b) increase in initial concentration
(c) total pressure
(d) decrease in total pressure
increase of reaction time
Fill up the blanks
Arrhenius equation shows the variation of __________with temperature
(a) Reaction rate
(b) Rate constant
(c) Energy of activation
(d) Frequency factor
Rate constant
The energy of activation of a chemical reaction
(a) is same as heat of reaction at constant pressure
(b) is the minimum energy which the molecules must have before the reaction can take place
(c) varies as fifth power of the temperature
(d) both (b) and (c)
is the minimum energy which the molecules must have before the reaction can take place
Rate constant ‘k’ and the absolute temperature T are related by collision theory (for bimolecular) as
(a) k T 1.5
(b) k e –E/RT
(c) k T
(d) k T
k T
Transition state theory relates the above quantities as
(a) k e –E/RT
(b) k Te –E/RT
(c) k T
(d) k T 1.5
NO ANSWER
Reactions with high activation energy are
(a) very temperature sensitive
(b) temperature insensitive
(c) always irreversible
(d) always reversible
very temperature sensitive
In autocalytic reactions
(a) one of the reactants acts as a catalyst
(b) one of the products acts as a catalyst
(c) catalyst has very high selectivity
(d) no catalyst is used
one of the products acts as a catalyst
With increase in temperature, the equilibrium conversion of a reversible exothermic reaction
(a) decreases
(d) increases
(c) remain unaffected
(d) decreases linearly with temperature
decreases
With decrease in temperature, the equilibrium conversion of a reversible endothermic reaction
(a) decreases
(b) increases
(c) remains unaffected
(d) increases linearly with temperature
decreases
The equilibrium constant of a chemical reaction
(a) increases in the presence of catalyst
(b) decreases in the presence of catalyst
(c) remains unaffected in the presence of a catalyst
(d) can either increase or decrease; depends on the type of catalyst
remains unaffected in the presence of a catalyst
Conversion increases with increase in temperature of
(a) Autocatalytic reaction
(b) Irreversible reaction
(c) Reversible endothermic reaction
(d) Reversible exothermic reaction
Reversible endothermic reaction
The heat of reaction
(a) depends on the pressure only
(b) depends on the mechanism of reaction only
(c) depends on both pressure and mechanism of reaction
(d) is independent of the mechanism of reaction
is independent of the mechanism of reaction
Integral method for analyzing the kinetic data is used
(a) when the data are scattered
(b) for testing specific mechanisms with simple rate expression
(c) both (a) and (b)
(d) none of these
both (a) and (b)
Differential method for analyzing the kinetic data is used
(a) for testing complicated mechanisms
(b) when the data are scattered
(c) when rate expressions are very simple
(d) none of these
for testing complicated mechanisms
Exposure of a photographic plate to produce a latent image is an example of
(a) Very slow reaction
(b) Very fast reaction
(c) Photochemical reaction
(d) Both (b) and (c)
Both (b) and (c)
A trickle bed reactor is one which
(a) has altogether three streams either entering or leaving
(b) processes three reactants at different flow rates
(c) processes three reactant with same flow rate
(d) employs all the three phases (i.e. solid liquid and gas)
employs all the three phases (i.e. solid liquid and gas)
According to Arrhenius equation of temperature dependency of rate constant for an elementary reaction
(a) k T
(b) k e-E/RT
(c) k Te-E/RT
(d) none of these
k e-E/RT
With increases in temperature, the rate constant obeying Arrhenius equation
(a) increases
(b) decreases
(c) decreases exponentially with temperature
(d) can either increase or decrease, depends on the frequency factor
increases
A batch reactor is characterized by
(a) constant residence time
(b) the variation in extent of reaction and properties of the reaction mixture with time
(c) variation in reactor volume
(d) very low conversion
the variation in extent of reaction and properties of the reaction mixture with time
A plug-flow reactor is characterized by
(a) high capacity
(b) presence of axial mixing
(c) presence of lateral mixing
(d) constant composition and temperature of reaction mixture
presence of lateral mixing
In a semi-batch reactor
(a) velocity of reaction can be controlled
(b) maximum conversion can be controlled
(c) both the as reactants flow counter-currently
(d) residence time is constant
velocity of reaction can be controlled
A back mix reactor
(a) is same as plug-flow reactor
(b) is same as ideal stirred tank reactor
(c) employs mixing in axial direction only
(d) is most suitable for gas phase reaction
is same as ideal stirred tank reactor
In a continuous flow stirred tank reactor the composition of the exit stream
(a) is same as that in the reactor
(b) is different than that in the reactor
(c) depends upon the flow rate of inlet stream
(d) none of these
Is same as that in the reactor
In an ideal tubular-flow reactor
(a) there is no mixing in longitudinal direction
(b) mixing takes place in radial direction
(c) there is a uniform velocity across the radius
(d) all (a), (b) and (c)
all (a), (b) and (c)
Space velocity
(a) describes the extensive operating characteristics of a tubular flow reactor
(b) is the maximum feed rate per unit volume of reactor for is given conversion
(c) is a measure of the case of the reaction job
(d) all (a), (b) and (c)
all (a), (b) and (c)
A high space velocity means that a given
(a) reaction can be accomplished with small reactor
(b) conversion can be obtained with a high feed rate
(c) both (a) and (b)
(d) none of these
both (a) and (b)
Space time in flow reactor is
(a) usually equal to the residence time
(b) the reciprocal of the space velocity
(c) a measure of its capacity
(d) both (a) and (c)
both (a) and (c)
A space-time of 3 hours for a flow reactor means that
(a) the time required to process one reactor volume of feed (measured at specified conditions) is 3 hour
(b) three reactor volumes of feed can be processed every hour
(c) it takes three hours to dump the entire volume of the reaction with feed
(d) conversion is cent per cent after three hour
the time required to process one reactor volume of feed (measured at specified conditions) is 3 hour
Space time equals the mean residence time
(a) when the density of the reaction mixture is constant
(b) for large diameter tubular reactor
(c) for narrow diameter tubular reactor
(d) for CSTR
when the density of the reaction mixture is constant
Fluidized bed reactor is characterized by
(a) uniformity of temperature
(b) comparatively smaller equipment
(c) very small pressure drop
(d) absence of continuous catalyst regeneration facility
uniformity of temperature
A batch reactor is
(a) suitable for gas-phase reaction on commercial scale
(b) suitable for liquid –phase reaction involving small production rate
(c) least expensive to operate for a given rate
(d) most suitable for very large production rate
Suitable for liquid–phase reaction involving small production rate
Which of the following is the most suitable for very high-pressure gas-phase reaction?
(a) batch reactor
(b) tubular flow reactor
(c) stirred tank reactor
(d) fluidized bed reactor
tubular flow reactor
For nearly isothermal operation involving large reaction time in a liquid –phase reaction, the most suitable reactor is
(a) stirred tank reactor
(b) tubular flow reactor
(c) batch reactor
(d) fixed bed reactor
stirred tank reactor
A stirred tank reactor compared to tubular-flow reactor provides
(a) more uniform operation condition
(b) permits operation at the optimum temperature for a long reaction time
(c) higher overall selectivity for a first order consecutive reaction
(d) all (a), (b) and (c)
all (a), (b) and (c)
For the same residence time, which will give the maximum conversion?
(a) single stirred tank (v=5liters)
(b) two stirred tank (each of 2.5liters) in series
(c) stirred tank followed by tubular flow reactor (each 2.5liters)
(d) single tubular flow reactor (v=5liters)
single tubular flow reactor (v=5liters)
Oil hydrogenated using nickel catalyst in a
(a) batch reactor
(b) slurry reactor
(c) fluidized bed reactor
(d) fixed bed reactor
slurry reactor
A second order reaction of the form A+B C is called a pseudo-first order reaction when
(a) CAO = CBO
(b) CAO > CBO
(c) CAO CBO
(d) CBO > CAO
A second order reaction of the form A+B C is called a pseudo-first order reaction when
(a) CAO = CBO
(b) CAO > CBO
(c) CAO CBO
(d) CBO > CAO
A second order reaction of the form A+B->C is called a pseudo-first order reaction when
(a) CAO = CBO
(b) CAO > CBO
(c) CAO CBO
(d) CBO > CAO
CBO > CAO
A first order irreversible reaction A->B is carried separately in a constant volume as well as a in a variable volume reactor for a particular period. It signifies that
(a) both conversion as well as concentration are same in the two reactors
(b) conversion in both will be the same but concentrations will be different in the two reactors
(c) both the conversion as well as concentrations will be different in the two reactors
(d) none of these
conversion in both will be the same but concentrations will be different in the two reactors
A space velocity of 5 hour means that
(a) five reactor volumes of feed (at specified conditions) are being fed into the reactor per hour
(b) after five hours, reactor is being filled with the feed
(c) cent percent conversion can be achieved in at least 5 hours
(d) a fixed conversion of a given batch of feed takes 5 hours
five reactor volumes of feed (at specified conditions) are being fed into the reactor per hour
Which of the following fixes the volume of a batch reactor for a particular conversion and production rate?
(a) operating conditions (e.g. pressure and temperature)
(b) rate constant
(c) density of mixture
(d) none of these
density of mixture
In a CSTR
(a) reaction rate varies with time
(b) concentration varies with time
(c) both (a) and (b) occur
(d) neither (a) nor (b) occurs
neither (a) nor (b) occurs
The use of space-time is preferred over the mean residence time in the design of
(a) batch reactor
(b) ideal tubular-flow reactor
(c) slurry reactor
(d) CSTR
ideal tubular-flow reactor
For all positive reaction orders for a particular duty
(a) mixed reactor is always larger than the plug-flow reactor
(b) the ratio of the volume of the mixed reactor to that of the plug-flow
reactor decreases with order
(c) reactor size is independent of the type of flow
(d) density variation during reaction affects design
mixed reactor is always larger than the plug-flow reactor
With the same reaction time, initial concentration and feed rate, the reaction 2A->B is carried out separately in CSTR and P.F. reactor of equal volumes. The conversion will be
(a) higher in P.F. reactor
(b) higher in CSTR
(c) same in both the reactors
(d) data insufficient; can’t be predicted
higher in P.F. reactor
For an autocatalytic reactor, the suitable reactor set up is
(a) P.F. reactors in series
(b) CSTR in series
(c) CSTR followed by P.F. reactor
(d) P.F. reactor followed by CSTR
CSTR followed by P.F. reactor
For multiple reactions, the reaction within the vessel affects the
(a) Size requirement
(b) Distribution of reaction product
(c) Both (a) and (b)
(d) Neither (a) nor (b)
Both (a) and (b)
A first order reaction requires two unequal sized CSTR. Which of the following gives a higher yield?
(a) Large reactor followed by smaller one
(b) Smaller reactor followed by larger one
(c) Either of the arrangement (a) or (b) will give the same yield
(d) Data insufficient; can’t be predicted
Either of the arrangement (a) or (b) will give the same yield
A first order reaction requires two equal sized CSTR. The conversion is
(a) Less when they are connected in series
(b) More when they are connected in series
(c) More when they are connected in parallel
(d) Same whether they are connected in series or parallel
More when they are connected in series
The concentration of A in a first order reaction A →B decreases
(a) Linearly with time
(b) Exponentially with time
(c) Very abruptly toward the end of the reaction
(d) Logarithmically with time
Exponentially with time
The concentration of A in a first order reaction A →B decreases
(a) Linearly with time
(b) Exponentially with time
(c) Very abruptly toward the end of the reaction
(d) Logarithmically with time
Which of the following is most suitable for isothermal reaction ?
(a) Batch reactor
(b) Back-mix reactor
(c) Plug-flow reactor
(d) Fixed bad reactor
Back-mix reactor
Which of the following is the optimum operating condition for an exothermic reversible reaction-taking place in a plug-flow reactor
(a)Temperature should be high in the beginning and decreased
towards the end of the reaction
(b) Very low temperature should be used throughout the reaction
(c) Very high temperature should be used throughout the reaction
(d) None of these
Temperature should be high in the beginning and decreased
With increase in the space-time of an irreversible isothermal reaction being carried out in a P.F. reactor, the conversion will
(a) Increase
(b) Decrease
(c) Remain same
(d) Data sufficient; can’t be predicted
Increase
The optimum performance for reactors operating in parallel is obtained when the feed stream is distributed in such a way that the
(a) Space time for each parallel line is same
(b) Space time for parallel lines is different
(c) Larger reactors have more space time compared to smaller ones
(d) None of these
Space time for each parallel line is same
Back mixing is most predominant in
(a) A well stirred reactor
(b) Plug-flow reactor
(c) A single CSTR
(d) CSTR connected in series
A single CSTR
The ratio of moles of a reactant converted into the desired product to that converted into unwanted product is called
(a) Operational yield
(b) Relative yield
(c) Selectivity
(d) None of these
Selectivity
The performance of a cascade of CSTR’s can be improved by adding
(a) a P.F. reactor in series
(b) a P.F. reactor in parallel
(c) More CSTR’s in series
(d) More CSTR’s in parallel
More CSTR’s in series
An auto thermal reactor is
(a) Most suitable for a second order reaction
(b) Most suitable for a reversible reaction
(c) Completely self supporting in its thermal energy requirements
(d) Isothermal in nature
Completely self supporting in its thermal energy requirements
For series reaction,the
(a) Relative yield is always greater for plug-flow reactor tha) for the single CSTR of the same volume
(b) Statement in a is wrong
(c) Relative yield decreases with increasing conversion
(d) Both (a) and (c) hold good
When a high liquid hold up is required in a reactor for a gas-liquid reaction,
use
(a) Packed column
(b) Spray column
(c) Tray column
(d) Bubble column
Bubble column
For reactions in parallel viz. A→P (desired product) and A→Q (unwanted product), if the order of the desired reaction is higher than that of the undesired reaction, a
(a) Batch rector is preferred over a single CSTR for high yield
(b) Tubular rector is preferred over a single CSTR for high yield
(c) Both (a) and (b)
(d) A single CSTR is the most suitable
Both (a) and (b)
In question 78, high yield would be favored ( for gas phase reactions)
(a) At high pressure
(b) At low pressure
(c) By the presence of the inner gases in the reactabt stream
(d) Both (b) and (c)
At high pressure
When all the limiting reactant is consumed in the reaction, the operation yield
(a) Is greater than relative yield
(b) Is smaller than relative yield
(c) Equals the relative yield
(d) Can be greater or smaller than relative yield, depends on the type of reaction
Equals the relative yield
Design of heterogeneous catalytic reactor involves consideration of
(a) Only chemical steps
(b) Only physical steps
(c) Both (a) and (b)
(d) Neither (a) and (b)
Both (a) and (b)
Pick out the wrong statement
(a) A catalyst does not alter the final position of equilibrium in a reversible reaction.
(b) A catalyst initiate a reaction
(c) A catalyst is specific in action
(d) A catalyst remain unchanged in chemical composition at the end of the reaction
A catalyst initiate a reaction
Catalyst is a substance which
(a) Increases the speed of chemical reaction
(b) Decreases the speed of chemical reaction
(c) Can either increase or decrease the speed of chemical reaction
(d) Alters the value of equilibrium constant in a reversible reaction
Can either increase or decrease the speed of chemical reaction
Catalyst carriers
(a) Have very high selectivity
(b) Increase the activity of a catalyst
(c) Provide large surface area with small amount of active material
(d) Inhibit catalyst poisoning
Provide large surface area with small amount of active material
A catalyst promoter
(a) Improves the activity of a catalyst
(b) Acts as a catalyst support
(c) Itself has very high activity
(d) All (a) (b) and (c)
Improves the activity of a catalyst
A catalyst inhibitor
(a) Lessens its selectivity
(b) May be useful for suppressing undesirable side reaction
(c) Is added in small quantity during the catalyst manufacture itself
(d) All (a) (b) and (c)
All (a) (b) and (c)
Carbon catalyst accumulated on the catalyst used in the gas oil cracking lies in the category of :
(a) Deposited poison
(b) Chemisorbed poison
(c) Selectivity poison
(d) Stability poison
Deposited poison
Slurry reactors are characterised by
(a) Lack of intra-particle diffusion resistance
(b) Presence of two mobile phase
(c) Both (a) and (b)
(d) Neither (a) nor (b)
Lack of intra-particle diffusion resistance
A reaction . A→ 3 B is conducted in a constant pressure vessel. Starting with pure A, the volume of the reaction mixture increase 3 times in 6 minutes. The final conversion is
(a) 0.33
(b) 0.50
(c) 1
(d) Data insufficient, can’t be predicted
1
The most suitable reactor for carrying out an auto-thermal reaction is
(a) Batch reactor
(b) CSTR
(c) Semi-batch reactor
(d) Plug-flow reactor
Semi-batch reactor
Which of the following factors control the design of a fluid solid reactor?
(a) The reaction kinetics for single particle
(b) The size distribution of solids being treated
(c) Flow patterns of solids and fluids in the reactor
(d) All (a) (b) and (c)
All (a) (b) and (c)
Kinetics of solid catalyst reaction can be studied in a
(a) Batch reactor
(b) Plug-flow reactor
(c) Mixed reactor
(d) None of these
Mixed reactor
For high conversion in highly exothermic solid catalyzed reaction, use a
(a) Fixed bed reactor
(b) Fluidized bed reactor followed by a fixed bed reactor
(c) Fixed bed reactor followed by a fluidized bed reactor
(d) Fluidized bed reactor
Fluidized bed reactor followed by a fixed bed reactor
For high conversion in highly exothermic solid catalyzed reaction, use a
(a) Fixed bed reactor
(b) Fluidized bed reactor followed by a fixed bed reactor
(c) Fixed bed reactor followed by a fluidized bed reactor
(d) Fluidized bed reactor
For high conversion in highly exothermic solid catalyzed reaction, use a
(a) Fixed bed reactor
(b) Fluidized bed reactor followed by a fixed bed reactor
(c) Fixed bed reactor followed by a fluidized bed reactor
(d) Fluidized bed reactor
In case of staged packed bed reactors carrying out exothermic reaction, use
(a) High recycle for pure glass
(b) Plug flow for dilute liquid require no large preheating of feed
(c) Cold shot operations for a dilute solution requiring large preheating to bring the steam up to the reaction temperature
(d) All (a) (b) and (c)
All (a) (b) and (c)
Which of the following will give the maximum gas conversion ?
(a) Fixed bed reactor
(b) fluidized reactor
(c) Semi-fluidized reactor
(d) Plug flow catalytic reactor
Semi-fluidized reactor
Which of the following factors control the deactivation of a porous catalyst pellet?
(a) Decay reactions
(b) Pore diffusion
(c) Form of surface attack of poison
(d) All (a) (b) and (c)
All (a) (b) and (c)
BET apparatus is used to determine the
(a) Specific surface of porous catalyst
(b) Pore size distribution
(c) Pore diameter
(d) Porosity of the catalyst bed
Specific surface of porous catalyst
If pore diffusion is the controlling step in a solid catalyzed reaction the catalyst
(a) Porosity is very important
(b) Porosity is less importance
(c) Internal surface is utilized efficiently
(d) None of these
Porosity is less importance
BET apparatus
(a) Measure the catalyst surface area directly
(b) Operates at very high pressure
(c) Is made entirely by stainless steel
(d) None of these
None of these
Helium-mercury method can be used to determine the
(a) Pore volume
(b) Solid density
(c) Porosity of catalyst particle
(d) All (a) (b) and (c)
All (a) (b) and (c)
