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

Abstract

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 molethanol/(gcat.·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 CHxOy 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.