Super-dry reforming of methane intensifies CO2 utilization via Le Chatelier's principle

Abstract

Efficient CO₂ transformation from a waste product to a carbon source for chemicals and fuels will require reaction conditions that effect its reduction. We developed a "super-dry" CH₄ reforming reaction for enhanced CO production from CH₄ and CO₂ We used Ni/MgAl₂O₄ as a CH₄-reforming catalyst, Fe₂O₃/MgAl₂O₄ as a solid oxygen carrier, and CaO/Al₂O₃ as a CO₂ sorbent. The isothermal coupling of these three different processes resulted in higher CO production as compared with that of conventional dry reforming, by avoiding back reactions with water. The reduction of iron oxide was intensified through CH₄ conversion to syngas over Ni and CO₂ extraction and storage as CaCO₃ CO₂ is then used for iron reoxidation and CO production, exploiting equilibrium shifts effected with inert gas sweeping (Le Chatelier's principle). Super-dry reforming uses up to three CO₂ molecules per CH₄ and offers a high CO space-time yield of 7.5 millimole CO per second per kilogram of iron at 1023 kelvin.