Connecting experimental degradation kinetics to theoretical models for photocatalytic reactors: The influence of mass transport limitations

Catalytic microreactors offer great opportunities to measure reaction kinetics, and parameters influencing the reaction. Although microreactors are quite useful for characterizing catalysts, it is important to understand the relative contributions of mass transport and intrinsic kinetics to the apparent reaction rate. In this paper, we demonstrate the importance of accounting for mass transport limitations in the photocatalytic degradation of Bisphenol A over titanium dioxide. Using analytical scaling laws available from literature and numerical simulations, we provide guidelines for the use of microreactors in characterizing (photo)catalysts. These guidelines identify the mass transport limited regime, or the reaction rate limited regime. The photocatalytic degradation of Bisphenol A was found to be mass transport limited at high light intensities (photon fluxes of above 25 mW/cm(2)). Neglecting the influence of mass transfer limitations in fitting kinetic data resulted in the exponent of reaction rate (beta) with respect to light intensity to be beta similar to 0:25, while including these effects gave an exponent directly proportional to the light intensity (beta similar to 1). These findings stress the importance of a correct inclusion of mass transport limitations. A simple analysis of the transverse Peclet number and second Damkohler number, to quantify the transport and reaction rates, is presented for our laminar flow reactor to illustrate the different limiting regimes. (C) 2021 The Authors. Published by Elsevier Ltd.

Automated summary

This paper investigates the application of catalytic microreactors in photocatalytic reactions, emphasizing the impact of mass transport limitations on reaction rates. The photocatalytic degradation of Bisphenol A was found to be mass transport limited at high light intensities. Proper consideration of mass transport limitations is crucial for accurately characterizing (photo)catalysts.