Mesoporous silica encapsulated core-shell NiRh@NiO nanocatalyst for performance-enhanced ethanol steam reforming

A novel mesoporous SiO₂ encapsulated core-shell NiRh@NiO nanostructure was constructed to enhance the activity and stability of ethanol steam reforming (ESR). At 550 °C and ethanol-WHSV = 21 h⁻¹, the specific activity and conversion loss (17 h) of NiRh@NiO@m-SiO₂ were 0.42 mol_ethanol/(g_cat.·h) and 10.9 %. The alloying of NiRh core, dominated NiO in shell, and abundant mesopore of SiO₂ were confirmed by systematic characterization techniques. The in situ DRIFTS results indicated that alloying Ni and Rh boosted ethoxide dehydrogenation to acetaldehyde and acetate demethanation to carbonate. ReaxFF molecular dynamics (MD) simulations suggested that NiO shell was conducive to water activation, which, in turn, promoted the conversion of CH_xO_y species. The SiO₂ encapsulation derived confinement effect inhibited both metal core sintering and leaching caused by the filamentous carbon. The abundant mesopores of SiO₂ ensured the facile in-diffusion of water and out-diffusion of carbonaceous products, suppressing carbon deposition within the SiO₂ encapsulation and the destruction of core-shell structure.