Question

The sequence of steps in a heterogeneous catalytic reaction is ____

(a) Diffusion → Adsorption → Reaction → Desorption → Diffusion → Mass transfer → Mass transfer

(b) Mass transfer → Diffusion → Adsorption → Reaction → Desorption → Diffusion → Mass transfer

(c) Mass transfer → Diffusion → Adsorption → Desorption → Diffusion → Mass transfer → Reaction

(d) Mass transfer → Adsorption → Diffusion Reaction → Desorption → Diffusion → Mass transfer

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Answer 1

The correct answer is (b) Mass transfer → Diffusion → Adsorption → Reaction → Desorption → Diffusion → Mass transfer

Easiest explanation: The catalytic reaction occurs by the mass transfer to the catalytic surface, followed by the diffusion of the reactant gas through the product layer. Reaction occurs at the gas – catalyst interface. Diffusion of the product gas occurs through the product layer. Mass transfer of the product gas occurs back through the gas film.