Cylindrical Catalyst Pellet

The catalyst pellets are, in most cases, fluidized by the action of a gas or liquid flowing through a reactor. The fluid enters at the bottom of a bed of catalyst particles and the particles are fluidized by the shear force that the fluid exerts on their surface, see the below figure.

At the same time, species dissolved in the fluid react on the surface and inside the porous catalyst particles. This example models the fluid flow past the pellet, the transport of species through the liquid and pellet media, and the reaction that takes place in the pellet.

We can see from this figure that the diffusion layer, in the free fluid surrounding the particle, is of non-uniform thickness. This results in a non-symmetrical concentration distribution along the outer surface of the particle. The diffusion layer at the particle surface, facing the inlet of the gas, is far thinner than that obtained behind the particle. Moreover, depletion of the reacting gas, along the main direction of flow, influences the concentration around the surface of and in the particle.

Click here to get more information about this model