Question

Thiele modulus will increase with the decrease of the size of the catalyst.

(a) True

(b) False

I had been asked this question by my college professor while I was bunking the class.

My question comes from Minimising Mass Transfer Effects topic in chapter Heterogenous Reactions of Bioprocess Engineering

Answer 1

Correct choice is (b) False

For explanation I would say: Thiele modulus (Φ) is proportional to the square of catalyst size (R^2 for spheres or b^2 for flat plates), reducing the catalyst size has a more dramatic effect on Φ than changes in any other variable. It is therefore a good way to improve the reaction rate. In principle, mass-transfer limitations can be completely overcome if the particle size is decreased sufficiently.