Hydrogen production by catalytic steam reforming of methane over iridium-doped ceria synthesized by solution combustion
Résumé
This work deals with the development of effective ceria-based materials for the catalytic production of hydrogen from CH4/H2O mixture. For this, pure ceria and ceria doped with noble metals (Ir, Rh) were prepared by a non-conventional one-pot method, namely solution combustion syntheses (SCS). The studied powders were physically characterized and tested in steam reforming of methane (SRM) at 750°C, under highly water-deficient conditions (CH4/H2O molar ratio of 10) with/without H2S. The as-prepared 0.1 wt% Ir-CeO2 catalyst appears highly active in SRM, resistant to carbon and irreversible poisoning by sulfur. Since the Ir-CeO2 powder was prepared by combustion synthesis for the first time, the post-treatment was optimized with regard to the targeted reaction. As seen in Fig. 1, the applied treatment is a key parameter for improving the performances of the Ir-CeO2 catalyst in the CH4/H2O reaction, while keeping a low amount of iridium (0.1 wt%). The observed catalytic performances after a mild thermo-chemical treatment were correlated with the structure of the active surface sites and their reactivity toward CH4. Furthermore, the reproducibility of the catalyst performances when the SCS route is used as preparation method was studied. Finally, the influence of the support and the preparation method was investigated through testing of 0.1 wt%Ir/CeO2 and 0.2 wt%Ir/SiO2-Al2O3 prepared by incipient wetness impregnation (IWI). This study demonstrates the relevance of using one-pot solution combustion synthesis for easy preparation of active Ir-CeO2 catalysts for the steam reforming of methane.