Unlocking exceptional diffusion of porous Ni@SiO2 nanocapsule catalysts for enhanced dry reforming of methane

Abstract

This paper introduces innovative porous Ni@SiO2 nanocapsule catalysts for high-temperature dry reforming of methane, synthesized through a selective etching method in a mild alkaline solution with varying CTAB concentrations. While core-shell catalysts have been proven effective in addressing issues like active metal sintering and coking, their dense inert oxide shells can impede intrinsic kinetics and hinder gas diffusion. The optimized catalyst, M-NSNC-2, showcases exceptional performance, featuring small Ni nanoparticles (5.3 nm) within a porous SiO2 nanocapsule (>900 m2g−1). M-NSNC-2 demonstrates outstanding methane conversion (>82%), stability (50 hours), and resistance to sintering, agglomeration, and higher-ordered carbon deposition. In comparison to dense Ni@SiO2 nanocapsules (NSNC), M-NSNC-2 exhibits superior performance with nearly 13-fold enhanced mass transfer diffusivity. Additionally, the porous Ni@SiO2 nanocapsule catalyst exhibits an apparent CH4 activation energy of 67.9 kJ/mol at a kinetic regime of 1800,000 mL gcat−1h−1, emphasizing its efficacy in catalyzing dry reforming of methane.