Factors affecting the long-term stability of mesoporous nickel-based catalysts in combined steam and dry reforming of methane

Abstract

An ordered mesoporous “one-pot” nickel–alumina catalyst (5 wt% Ni) was synthesized using the evaporation-induced self-assembly method. Compared to an impregnated and a non-porous catalyst, the ordered “one-pot” Ni–alumina sample displayed, after in situ reduction, the highest and the most stable catalytic performances along a 40 h run at 800 °C in combined steam and dry reforming of methane, with conversion and selectivity values close to the thermodynamically expected ones. Both the confinement of well-dispersed Ni nanoparticles within the structured Al₂O₃ framework and the strengthened Ni–support interaction compared to other catalysts are shown to be key factors accounting for the high catalytic activity and stability. In contrast to alumina that appears as an effective support of Ni for catalytic combined methane reforming, neither mesoporous (SBA-15) nor macroporous (CeliteS, diatoms) silica is appropriate due to rapid deactivation by partial reoxidation of the metallic Ni⁰ active phase in the conditions of the reaction.