Plasma-Assisted Chemical Looping Oxidative Coupling of Methane over LaMnO3 at 400 °C

Chemical looping oxidative coupling of methane (CLOCM) is a promising method for the direct conversion of methane to produce C2+ hydrocarbons. However, high reaction temperatures (800–900 °C) are required to ensure high redox activity, leading to the server sintering of oxygen carriers. Here, we report plasma-assisted chemical looping oxidative coupling of methane and investigate its performance under mild conditions (100–400 °C). The results demonstrate that the plasma-assisted CLOCM reaction can be initiated at temperatures as low as 100 °C. Particularly, LaMnO3 shows a high CH4 conversion of 35.33% and a C2+ yield of 12.26% at 400 °C. The performance merely decreased after 20 redox cycles. A mechanistic study implies that the high-performance results from plasma generate high-energy electrons (1–20 eV) to activate methane (4.3 eV) at low temperatures and to increase the electron vacancies on the surface of the oxygen carrier for binding oxygen species, inhibiting methane overoxidation. We hope that the promotion effect of plasma can be extended to enable more fuel conversion processes under mild conditions.