Dry Reforming of Methane: Catalytic Performance and Stability of Ir Catalysts Supported on γ-Al2O3, Zr0.92Y0.08O2-δ (YSZ) or Ce0.9Gd0.1O2-δ (GDC) Supports

The impact of the support on the Ir-catalyzed dry (CO2) reforming of methane (DRM) reaction is explored in the present study. With this aim, supported iridium catalysts Ir/gamma-Al2O3, Ir/YSZ and Ir/GDC with 1 wt% iridium loading, using gamma-Al2O3, 8 mol% Y2O3 stabilized ZrO2 (YSZ: Zr0.92Y0.08O2-delta) and 10 mol% Gd2O3 doped CeO2 (GDC: Ce0.9Gd0.1O2-delta) as supports were comparatively studied in the temperature range of 400-850 degrees C. The feasibility of tuning the catalytic performance and/or stability of the Ir active phase during DRM reaction, via support-induced interactions, was investigated. All catalysts were found to be extremely active and stable over time on stream. No significant effects induced by the support were observed at the high operating temperature of DRM. However, opposite to Ir/gamma-Al2O3 and Ir/YSZ samples, Ir/GDC provides the benefit to be stable in oxidation steps and/or oxidation-reduction cycles. This is of significant practical importance since such treatment procedures are often used in practice for catalysts regeneration. Besides catalytic performance measurements, extended hydrogen temperature-programmed reduction experiments, supported further by transmission electron microscopy characterization studies were carried out in order to reveal the impact of the support on the aforementioned stability and its origin.