Y-Cu Synergistic Promotion in Ni/SiO2 Catalysts: Controlling Metal Dispersion and Carbon Diffusion toward Enhanced Stability in Methane Decomposition

Abstract

Catalytic methane decomposition (CMD) is considered a viable route for producing clean hydrogen, accompanied by the formation of carbon nanostructures as useful products. However, achieving high activity and long-term stability remains a critical challenge due to Ni particle sintering and carbon encapsulation. This work demonstrates that the co-introduction of Ni with Y, Mo, and Zr promoters helps tune the interaction between Ni and mesoporous SiO2 support, simultaneously controlling Ni sintering and ensuring the availability of sufficient active Ni sites for the CMD reaction. Among the synthesized catalysts, Ni5Y/S sample provides the highest performance, delivering superior methane conversion (XCH4 = 64%) compared to the Zr- and Mo-promoted samples, owing to the presence of well-stabilized Ni nanoparticles. Furthermore, Cu incorporation at various loadings was investigated to prevent encapsulation of metallic Ni by facilitating carbon diffusion, thereby improving the catalyst stability. The catalyst containing 9 wt% Cu exhibits excellent stability with a deactivation rate of only 0.56 %/h during CMD stability test. These results offer an effective strategy for designing advanced Ni-based catalysts for sustainable H2 generation through CMD.