Optimal catalyst activity profiles in pellets—VII. The case of arbitrary reaction kinetics with finite external heat and mass transport resistances

Optimal catalyst activity profiles in pellets: 9. Study of ethylene epoxidation

“…This behavior results from intraphase temperature gradients and is qualitatively consistent with previous theoretical findings. It has been shown (Morbidelli et al, 1985;Chemburkar et al, 1987;Vayenas and Pavlou, 1987) that even for positive-order reactions, the optimum location to maximize catalyst effectiveness moves toward the pellet interior, if the product of the dimensionless heat of reaction @ and dimensionless activation energy y is sufficiently large and occurs solely because of the intrapellet temperature gradient. This product is proportional to the reactant concentration and inversely proportional to the square of the bulk temperature, by -C,/T/Z.…”