Diffusion and reaction in porous networks

The present paper reviews three-dimensional random network models of cataly st support structures. Multicomponent diffusion in the individual pores of the network is described by the dusty-gas approach. In contrast to previous publications, the present network model can be applied to any common react ion kinetics. This becomes inevitable in order to make three-dimensional ne twork models applicable to practical problems in the industry. The present model is closely connected to measurable quantities which may be obtained b y standard equipment. Examples of pore structure optimizations with respect to various optimization criteria are given. Investigations of depositions within the pores by percolation theoretical methods are described. Results of simulations are compared to measurements in a single-pellet diffusion re actor. The importance of surface diffusion is stressed. (C)1999 Elsevier Sc ience B.V. All rights reserved.