Secondary effectiveness factors for catalytic reactions in series: extension to slab, cylindrical, and spherical geometries

Abstract

Thiele moduli and effectiveness factors are powerful ways to factor for diffusion limitations in heterogeneously catalyzed reactions. They have been developed for different rate laws, different geometries, as well as non-isothermal reactions. A recent study [B. Peters, ACS Catal., 2020, 10, 4319–4325] reported new ‘secondary effectiveness factors’ for a series of catalytic reactions A → B → C in a slab geometry. This paper generalizes the secondary effectiveness factors to spherical and cylindrical geometries. We illustrate their use for a batch slurry reactor with catalyst particles of different geometry. For molecular sieves, we show how partition coefficients between the solution and the catalyst particle can enhance the selectivity to the intermediate B. Finally, we introduce generalized expressions for the concentration of B and the ‘secondary’ effectiveness factor for different geometries.