From mechanistic to kinetic analyses of ethanol steam reforming over Ir/CeO2 catalyst

•Over a Ir/ceria catalyst, a bifunctional mechanism allows to design a kinetic modeling in good fit with kinetic data.•Interface sites (metal and support) seem to control the overall rate of the reaction of ethanol steam reforming.•This control corresponds to the transition from C2 chemistry on ceria to C1 chemistry on noble metal.•Catalyst aging via ceria and metal sintering can be directly handled by the proposed kinetic model.

This work presents a kinetic analysis of ethanol steam reforming (ESR) over a performing Ir/CeO2 catalyst based on a bi-functional mechanism. A first conventional power-law based kinetic study was carried out by varying the main operating parameters (temperature, steam/ethanol molar ratio and partial pressure of products). A limited fit was achieved between the experimental data and the data calculated from this model based on a single type of site, demonstrating the need of a kinetic analysis integrating more closely the demonstrated bi-functional mechanism of the reaction. A kinetic model considering two distinct adsorption sites, on ceria support and on iridium particles, was then considered and only reactions involving the two types of sites, i.e. occurring at the ceria/metal interface, were used to build that model. A good agreement between the experimental data and the model was obtained, without systematic deviations. The central role of the metal-support interface was also consistent with the deactivation of this catalyst upon sintering, related to both changes in metal and support dispersion with time on stream.