Project ForgeChemical Reaction Engineering
Ideal Reactor Design
GATE 2012
Hard
Consider the reaction scheme A→(k1)B→(k2)C. Both the reactions are first-order. The activation energies for k1 and k2 are 80 and 20 kJ/mol, respectively. To maximize the yield of B, it is preferable to use
- ACSTR and high temperature
- PFR and high temperature
- CCSTR and low temperature
- DPFR and low temperature
Explanation
A PFR always gives a higher maximum intermediate (B) concentration than a CSTR for series reactions at the same conditions. Since Ea1(80)≫Ea2(20), k1 grows much faster than k2 with temperature — operating at HIGH temperature increases the k1/k2 ratio, favoring formation of B over its further conversion to C. So PFR and high temperature.
Source: GATE CH 2012 (2012)
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