Effect on order of reaction

For a n^th order reaction, Thiele modulus is given as

For significant intra-pellet diffusion limitations,

The rate is given as

(4)

If intrapellet diffusion is not considered the rate can be written as

(5)

Here is called the apparent order. Comparing equation (4) and (5)

The above relations shows how due to presence of pore diffusion limitations, for zero order and second order reactions, the apparent reaction order appear reduced.