On Shape Normalization for Non-Uniformly Active Catalyst Pellets. III.
Technical summary rept.,
WISCONSIN UNIV-MADISON MATHEMATICS RESEARCH CENTER
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A new shape normalization for non-uniformly active isothermal catalyst pellets is developed. It is based on the volume average of catalyst activity in a thin reaction zone near the external surface of the active catalyst region, wherein the reaction occurs in the diffusion-controlled regime. This normalization permits inclusion of those catalyst activity profiles that become zero at the external surface of the catalytically active region, which were excluded from previous normalizations. When the surface activity is nonzero, results reduce to those obtained earlier. The normalization provides exactly the slope of the effectiveness factor - Thiele modulus curves, for all pellet shapes and activity profiles, in the limit of diffusion-control. The development is initially made for first-order reactions, and then generalized to include arbitrary reaction rate expressions. Effects of finite external mass transfer resistances are also discussed.
- Physical Chemistry
- Statistics and Probability