MULTICOMPONENT DIFFUSION AND REACTION IN 3-DIMENSIONAL NETWORKS - GENERAL KINETICS

Over the last 10 years the design of catalyst particles and porous str uctures has made considerable progress. Due to the complicated interac tion of diffusion and reaction in catalysts, more detailed models of p orous structures are needed. We have based our model on a three-dimens ional network of interconnected cylindrical pores as pore model, altho ugh the treatment is applicable to alternative pore geometries, e.g., slit pores. The network assumed has predefined distributions of pore r adii, connectivity, and porosity. Mass transport in the individual por es of the network is described by the dusty-gas model. In contrast to previous publications, the present network model can be applied to any common reaction kinetics. This becomes quite inevitable in order to m ake three-dimensional network models applicable to practical problems in industry. To solve the mass balances within the entire network, the mass balances for individual pores have to be solved simultaneously, since these mass balances are coupled by the boundary conditions at th e nodes of the network. The system of differential equations has been solved by the finite-difference method. To solve the resulting large n onlinear system, a Schur complement method was employed. Due to a deco upling technique, the Schur complement method has relatively small com puter storage requirements. The use of the algorithm is demonstrated f or a complex reaction network.