Mechanism on CMD reaction regulated by supports and promoters of Fe-based catalysts

Methane cracking technology for low -carbon energy conversion to produce hydrogen is a key technical approach in the pursuit of fossil energy decarbonization. Catalytic methane decomposition (CMD) is a process that accomplishes the fundamental removal of carbon from fossil energy without oxygen, producing high -quality carbon -based materials and H 2 . The functionality of supports and promoters was investigated using inorganic metal oxide support Al 2 O 3 , supported active metal Fe, and cocatalyst K. The results show that the Al 2 O 3 - Fe catalyst achieves the highest CH 4 conversion of 65% at 850 degrees C, with a gas -phase H 2 yield of 1189.72 mmol/g Fe within 3 h, and a solid -phase carbon yield of 6.32 g/g F e , significantly higher than at 750 degrees C. The Al 2 O 3 - Fe-K catalyst achieves a methane conversion rate of 66.28% at 850 degrees C for 1.5 h, exhibiting relatively fast deactivation. The Al 2 O 3 - Fe catalyst catalyzes the formation of carbon nanotubes (CNTs) through methane cracking, resulting in mainly 'chain -locked' morphology. The promoter K acts on the surrounding metal clusters to influence the dispersion of active metal. The Al 2 O 3 - Fe-K catalyst is more favorable for the production of 'bamboo -shaped' carbon nanotubes, suggesting that K has a more significant impact on shaping the CNTs' products.