Enhanced methane decomposition over Ni-Co/MCM-41 Catalysts: Effect of Co doping on Activity, Stability, and carbon morphology

Catalytic methane decomposition (CMD) offers a sustainable pathway for producing COx-free hydrogen along with valuable solid carbon, suitable for applications in composites, electronics, and energy storage. This study focuses on synthesizing monometallic Ni catalysts supported on MCM-41 to determine the optimal Ni loading at 550 °C for achieving high methane conversion and stability in fixed-bed reactor. Thermal stability was further enhanced through optimal Co doping, with improvements in activity attributed to reduced metal sintering and coking. The most effective bimetallic catalyst (10Ni2.5Co/MCM-41), was investigated to evaluate the impact of feed concentration, reaction temperature, and space velocity (ranging from 5000 to 12000 mL/h.g_cat) on methane conversion. A notable stable methane conversion of ∼ 68 %, over a duration of 4 h, at 650 °C was achieved, marking one of the highest reported values for Ni-Co catalysts supported on MCM-41. The least stable catalyst, 10Ni10Co/MCM-41, was effectively regenerated over five cycles using cyclic CO₂ gasification, successfully restoring its catalytic activity. Advanced characterization revealed distinct carbon morphologies, with TEM images showing fishbone-type carbon for 10Ni/MCM-41 and hollow-core structures for 10Ni2.5Co/MCM-41, while TGA analysis confirmed the formation of graphitic carbon without amorphous content.