Experimental and kinetic study on the solar-driven iron-based chemical looping dry reforming of methane

The chemical looping dry reforming of methane (CL-DRM) represents a promising pathway for large-scale engineering applications of thermochemical decarbonization techniques. To elucidate the intricate reaction mechanism of CL-DRM, a comprehensive kinetic model encompassing both gas-phase reactions and ferrite surface reactions is developed in this study. This model can serve as a numerical foundation for tracing the reaction progression of comparable iron-based oxygen carriers, allowing visualization of all reaction pathways and further determination of optimal reaction conditions. Besides, foam-structured materials employing NiO-doped CoFe₂O₄ as oxygen carriers were prepared to conduct application experiments for the CL-DRM on a self-designed solar thermochemical platform. The experimental outcomes, obtained under temperature conditions guided by numerical predictions, validate the promising feasibility of employing Ni-doped ferrite in the CL-DRM reaction system. At a reaction temperature of only 1150 K, remarkable peaks in H₂ yield of 23.5 mL min⁻¹ g⁻¹, CO yield of 11.6 mL min⁻¹ g⁻¹, and CH₄ conversion around 90% are attained, with a net solar-to-fuel conversion efficiency of 1.93%. A comparative analysis conducted with the conventional two-step thermochemical cycle under the same experimental setup underscores the notable advantages of CL-DRM in terms of syngas production capacity and conversion efficiency. Consequently, CL-DRM can be regarded as a pivotal transition towards the realization of a fully carbon-free thermochemical technology.