Production of CO2-free hydrogen via catalytic methane decomposition over Ce-promoted Ni/Al2O3 catalysts

Catalytic methane decomposition (CMD) is a promising reaction for CO 2 -free hydrogen production, as it generates no CO 2 emissions and produces solid carbon byproducts. However, catalyst deactivation due to carbon accumulation necessitates the development of catalysts with high activity, stability, and high capacity for carbon products. In this study, Ce-promoted Ni/Al 2 O 3 catalysts were synthesized with varying Ce loadings to investigate the role of Ce in enhancing catalyst performance. The addition of Ce was found to weaken the interaction between Ni and Al 2 O 3 , thereby increasing the surface concentration of metallic Ni 0 and improving catalytic activity. Nevertheless, excessive Ce loading resulted in performance deterioration, primarily due to a significant reduction in mesoporous volume. This loss of physical space limited the growth of carbon products and hindered catalyst effectiveness. The results highlight the need to balance the promotional effects of Ce with the preservation of pore structure to optimize catalyst design for CMD. • Ce addition enhanced catalytic activities of Ni catalysts for methane decomposition. • Increasing Ce loading weakened the interaction between Ni and Al 2 O 3 support. • Excessive Ce loading led to a decrease in final carbon yield. • Pore volume played a critical role in the accumulation of carbon materials.