Highly efficient methane decomposition to H₂ and CO₂ reduction to CO via redox looping of Ca₂Fe_xAl_2-xO₅ supported Ni_yFe_3-yO₄ nanoparticles

Catalytic methane decomposition (CMD) due to its various potentials including production of CO_x free H₂ and technically simpleness, but is very challenging due to the lack of efficient, stable, and carbon-separable catalysts. An innovative chemical looping methane decomposition with CO₂ reduction (CLMDCR) was developed to bridge the gap via the reduction → CMD → oxidation looping of a catalytic oxygen carrier (COC) for H₂ production, deposited carbon separation, and CO₂ reduction to CO. As high as 96.3 vol.% and 95.2 vol.% purities of H₂ and CO can be generated using the COC (Ni_yFe_3-yO₄-Ca₂Fe_xAl_2-xO₅), superior to those obtained with state-of-the-art CH₄ dry reforming. The COC shows not only high activities but also remarkable durability as demonstrated with 20 cyclic CLMDCR tests. Experimental results indicate that the long-term redox durability of COC is attributed to its atomic homogenization through the phase transformations of Ni_yFe_3-yO₄ ↔ Ni-Fe and Ca₂Fe_1.52Al_0.48O₅ ↔ CaO + Fe + Ca₂Fe_xAl_2-xO₅.