THE DIFFUSION-REACTION PROBLEM IN TRIPHASE CATALYSIS

Phase transfer catalysis has been in use for over three decades, but t riphase catalysis, where the phase transfer catalyst is immobilized on a solid support, is of much more recent origin. Polymeric solids are among the most commonly used supports, but they lead to diffusion-reac tion problems considerably more complicated than in conventional solid catalyzed reactions. Since, rather unaccountably, triphase catalysis has not been a subject of common interest in chemical engineering, a b rief review of the field is given with emphasis on the role of catalys t synthesis in understanding its diffusional implications. This is fol lowed by the development of a mathematical model for analyzing the dif fusion-reaction problem in a common triphase catalytic system: liquid- liquid-solid triphase catalysis.