Project ForgeChemical Reaction Engineering
Reaction Kinetics
GATE 2019
Medium
For a first order reaction in a porous spherical catalyst pellet, diffusional effects are most likely to lower the observed rate of reaction for
- Aslow reaction in a pellet of small diameter
- Bslow reaction in a pellet of large diameter
- Cfast reaction in a pellet of small diameter
- fast reaction in a pellet of large diameter
Explanation
Diffusional limitation is governed by the Thiele modulus, which increases with both the intrinsic rate constant and the pellet size — a fast reaction in a large pellet has the highest Thiele modulus and the strongest diffusion limitation.
Source: GATE CH 2019 (2019)
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