Triphase catalysis: a correlation for Sherwood number using the rotating disk contactor (RDC) developed earlier

Triphase catalysis (TPC) has the potential for conducting phase-transfer ca talyzed reactions in the continuous mode. However, there is so far no indus trial acceptance of this possibility since the reaction rates achieved are usually low due to diffusional limitations. Triphase catalytic systems are strongly influenced by mass transfer, and thus an experimental technique us ing a rotating disk contactor was specifically designed by the authors to e stimate individual mass transfer coefficients for the liquid phases [Glatze r, Desikan, & Doraiswamy, Chem. Eng. Sci. 53 (13) (1998) 2431]. The key to precise measurements is the choice of the model system which should have an almost negligible noncatalytic reaction but yet a high enough catalytic ra te to be mass transfer controlled at low agitation speeds. The synthesis of octyl acetate from octyl bromide and potassium acetate has these attribute s and was chosen as the test system. The reaction was mediated by polymer-s upported tributylmethylammonium chloride or the corresponding phosphonium c hloride. Mass transfer coefficients could be determined as a function of th e agitation speed. Despite limited available data, an equation that correla tes the Sherwood number to the Reynolds and Schmidt numbers has been propos ed. (C) 2001 Published by Elsevier Science Ltd.