Question

Thiele modulus is used for the solid catalyst.

(a) True

(b) False

This question was addressed to me in an international level competition.

My doubt is from Minimising Mass Transfer Effects topic in chapter Heterogenous Reactions of Bioprocess Engineering

Answer 1

The correct answer is:

(a) True

The Thiele modulus is a dimensionless number that characterizes the relative importance of diffusion versus reaction rate within a solid catalyst particle. It is specifically used to describe the performance of solid catalysts in heterogeneous reactions, particularly when the catalyst is in a particulate form (e.g., pellets or beads).

• When the Thiele modulus is large, it indicates that reaction kinetics dominate over mass transfer, which may result in the core of the catalyst particle being underutilized (since reactants can't diffuse quickly enough to the center).
• When the Thiele modulus is small, it suggests that diffusion is limiting the reaction, and the entire particle can be considered to participate equally in the reaction.

Thus, the Thiele modulus is directly related to the solid catalyst and helps assess how effectively the catalyst particle is utilized in a reaction system, particularly when mass transfer limitations exist.

So, True is the correct answer.