Deactivation phenomena by site poisoning and pore blockage: The effect of catalyst size, pore size, and pore size distribution

The problem of catalyst deactivation by active site poisoning and pore blockage is analyzed. The effect of catalyst size, average pore size, and pore size distribution on the phenomenon of deactivation is investigated for two simple pore structure models, i.e., the "single pore" and "parallel bundle of pores" models. It is shown that the overall catalytic behavior and performance strongly depend on the catalyst's physical properties, such as its size, pore size, and pore size distribution. The mathematical models studied here are admittedly only oversimplified analogs of the complex physicochemical phenomena occurring during realistic industrial processes. The main qualitative features, however, of the overall catalytic behavior predicted here are the result of basic and strongly counteracting, underlying physicochemical processes. As such, the types of catalytic behavior described are not strongly dependent on the particular kinetic and diffusion models employed but are closely associated with macromolecular catalytic reaction systems that deactivate by simultaneous active site coverage and pore blockage.