Catalyst Deactivation by Pore Plugging and Active Site Poisoning Mechanisms

A catalyst deactivation model is formulated which includes the combined effects of pore plugging and active site poisoning. Intraparticle mass transfer is described by an equation which accounts for the configurational nature of diffusion, and poison deposition is assumed to be in accord with a parallel poisoning mechanism. A computational algorithm is presented for solving the highly nonlinear system equations numerically. The relative extent of deactivation by pore plugging and active site poisoning is determined by a dimensionless parameter, α, and several examples illustrate the effects that this parameter and other system parameters have upon the computed results. The model when combined with laboratory experiments should prove useful in optimizing catalyst pore size.