High-Performance Ni-Fe Redox Catalysts for Selective CH₄ to Syngas Conversion via Chemical Looping

In traditional steam reforming of CH₄, the CH₄ conversion and its selectivity to CO and H₂ are thermodynamically limited. In this work, we designed a series of Ni-Fe redox catalysts with varying Ni/Fe ratios. The Ni-Fe redox catalysts could function as oxygen carriers to selectively convert CH₄ to syngas via chemical looping. The selectivity to CO was dramatically enhanced via a selective conversion route of CH₄ to C and H₂ in the reduction, followed by C gasification to syngas with hot steam. Taking the advantages of the highly reactive Ni species for CH₄ activation and Fe species for water splitting, together with the resulting NiFe alloy in the reduced catalyst for catalytic CH₄ decomposition, high CH₄ conversion up to 97.5% and CO selectivity up to 92.9% were achieved at 900 °C with productivity of CO and H₂ of 9.6 and 29.0 mol kg_catalyst^-1, respectively, on equimolar Ni-Fe catalyst.