Overall effectiveness factor of an assemblage of catalyst pellets with different sizes or properties

Abstract Catalyst assemblages comprising pellets with distributed sizes or physicochemical properties are ubiquitous in industrial processes; yet accurately predicting their overall effectiveness factors remains a challenge due to complex diffusion–reaction interactions. This study introduces a practical and novel integrated Thiele modulus to compute this factor for polydisperse catalyst systems, unifying geometric, kinetic, and diffusive heterogeneities into a single framework. The proposed model eliminates the need for complex analytical or time‐consuming numerical solutions for pellets of arbitrary shape, offering a significant simplification for industrial design. Validated for diverse geometries (spheres, cylinders, parallelepipeds, cones, etc.), the presented method based on the overall Thiele modulus demonstrates acceptable accuracy for all the investigated cases.