Enhanced methane conversion in chemical looping partial oxidation systems using a copper doping modification

Abstract

Chemical looping partial oxidation (CLPO) is a promising strategy of methane conversion to syngas with low cost and minimal environmental impact. A major challenge is the development of oxygen carriers that have high reactivity, high oxygen carrying capacity, and recyclability. We demonstrate that the addition of a low concentration (1%) of copper dopant to iron-based oxygen carriers can dramatically enhance the reactivity in CLPO process at low temperatures while maintaining the recyclability of these carriers. With the dopant, the methane conversion rate at 700 °C is 470% higher than that of carriers without the dopant. These results are substantiated by ab initio DFT + U and thermochemistry analyses. It is noted that operating a chemical looping system at 700 °C can result in energy consumption savings of ∼35% as compared to a chemical looping operation at 1000 °C. Thus, our findings provide a pathway to significantly lowering the methane reaction temperature in chemical looping systems, which will lead to substantial energy savings with desired oxygen carrier recyclability.