Which of the following will give maximum gas conversion?
A. Fixed bed reactor
B. Fluidised bed reactor
C. Semi-fluidised bed reactor
D. Plug-flow catalytic reactor
Answer: Option C
This Question Belongs to Chemical Engineering >> Chemical Reaction Engineering
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A. $${{\text{k}}_{\text{e}}}{\text{ff}} = {\text{k}} + {{\text{k}}_{\text{g}}}$$
B. $${{\text{k}}_{\text{e}}}{\text{ff}} = \frac{{{\text{k}} + {{\text{k}}_{\text{g}}}}}{2}$$
C. $${{\text{k}}_{\text{e}}}{\text{ff}} = {\left( {{\text{k}}{{\text{k}}_{\text{g}}}} \right)^{\frac{1}{2}}}$$
D. $$\frac{1}{{{{\text{k}}_{\text{e}}}{\text{ff}}}} = \frac{1}{{\text{k}}} + \frac{1}{{{{\text{k}}_{\text{g}}}}}$$
The half life period of a first order reaction is given by (where, K = rate constant. )
A. 1.5 K
B. 2.5 K
C. $$\frac{{0.693}}{{\text{K}}}$$
D. 6.93 K
Catalyst is a substance, which __________ chemical reaction.
A. Increases the speed of a
B. Decreases the speed of a
C. Can either increase or decrease the speed of a
D. Alters the value of equilibrium constant in a reversible
A. $$ \propto {\text{CA}}$$
B. $$ \propto \frac{1}{{{\text{CA}}}}$$
C. Independent of temperature
D. None of these
The correct answer is:
D. Plug-flow catalytic reactor
Explanation:
To maximize gas conversion in a chemical reactor, the flow pattern and catalytic effectiveness are crucial.
Why Plug-flow catalytic reactor gives maximum conversion:
In a plug-flow reactor (PFR), the reactants move through the reactor without back-mixing.
The concentration of reactants is highest at the inlet, which maximizes the reaction rate at the start.
As the gas flows forward, the conversion gradually increases along the reactor length.
When a catalyst is used, the effectiveness increases due to high reactant concentration at the catalyst surface in the inlet region.
Comparisons:
A. Fixed bed reactor
→ May behave like a PFR if ideal, but real systems often have non-idealities (channeling, heat/mass transfer issues).
B. Fluidised bed reactor
→ Behaves closer to a CSTR due to excellent mixing. While good for heat transfer and solids handling, it gives lower conversion per pass than PFRs.
C. Semi-fluidised bed reactor
→ Intermediate between fixed and fluidised beds; not optimal for maximum conversion.
✅ Final Answer:
D. Plug-flow catalytic reactor