Hydrogen Production via Low-Temperature Steam–Methane Reforming Using Ni–CeO2–Al2O3 Hybrid Nanoparticle Clusters as Catalysts

The hybrid nanostructures, Ni-only and Ni–CeO2 nanoparticles decorated on Al2O3 nanoparticle clusters (Ni–Al2O3 NPC and Ni–CeO2–Al2O3 NPC, respectively), were successfully synthesized as catalysts for steam reforming of methane (SRM). A substantial amount of metal–support interface was created in the hybrid nanostructure via aerosol-based evaporation-induced self-assembly, by which ultrafine Ni crystallites (≈6 nm) and tunable chemical composition achieved simultaneously. Addition of Al2O3 NPC increased metal surface area and also suppressed Ni sintering in the hybrid nanostructure during catalysis. Hybridization with CeO2 nanoparticles significantly improved catalytic activity and stability of the Ni-based catalyst, especially in the absence of Al2O3 NPC, and the amount of coke formation was shown to be effectively suppressed by >3×. A superior high catalytic performance of the hybrid nanostructures achieved: a low starting temperature (400 °C), remarkable activity at low temperature (turnover frequencies of methane conversion of 0.8 s–1 at 500 °C), ideal H2 yield (≈3× of the converted methane), and high operation stability over 8 h reaction. The work demonstrates a prototype study of gas-phase synthesis of hybrid nanocatalysts using Al2O3 NPC as the support matrix to achieve a very high activity at a low-temperature operation of SRM, which has shown promise for an advance of methane-based energy applications.