Impact of reducing the channel diameter on heterogeneous gas reactions in an isothermal monolith

Abstract

The benefits and drawbacks of micro-monoliths with respect to conventional monoliths, for heterogeneous reactions in a gaseous phase, have been described experimentally in numerous studies. In this work, the interest of using a micro-monolith is demonstrated by achieving a preliminary analysis and by solving an isothermal model of the monolith. Ethanol steam reforming to produce hydrogen is considered as a case study to evaluate the performances of three different devices (having different channel diameters) used in an experimental study of Casanovas et al. [1]. To get a better understanding of the experimental results, simulations are performed in a new way, more suitable for a clearer comparison between the different devices. In kinetic regime, the better performance of a micro-monolith with respect to other devices is due to a higher catalyst amount per unit of reactor volume. The main interest of using a micro-monolith is a high compactness for a quite slow chemical reaction, while for a very fast one, the main interest is to avoid mass transfer limitations. Finally, a map representing the Damkhöler number for a first order chemical reaction provides information to wisely choose the channel diameter of a monolith.