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GATE 2022 CH – Question 26

Chemical Reaction Engineering · Heterogeneous catalysis, diffusion effects and catalyst deactivation · 1 mark · Multiple choice

The reaction $A \to B$ is carried out isothermally on a porous catalyst. The intrinsic reaction rate is $kC_A^2$, where $k$ is the rate constant and $C_A$ is the concentration of $A$. If the reaction is strongly pore-diffusion controlled, the observed order of the reaction is

  1. 1
  2. 2
  3. $3/2$
  4. $\sqrt{2}$

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Correct answer: (C) $3/2$

Explanation

In the strong pore diffusion regime the observed order is $\frac{n + 1}{2}$ for an intrinsic order $n$. With $n = 2$ this is $\frac{3}{2}$.