A first order reaction A → B occurs in an isothermal porous catalyst pellet of spherical shape. If the concentration of A at the centre of the pellet is much less than at the external surface, the process is limited by__________________?
Correct answer: D. Diffusion within the pellet
- A. None of the above
- B. Reaction
- C. External mass transfer
- D. Diffusion within the pellet
Explanation
A much lower concentration at the pellet centre than at its surface indicates a steep internal concentration gradient. Reactant diffusion through the pores is therefore limiting the overall process, rather than the intrinsic reaction or external film transfer.
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