Low-Temperature and Highly Efficient Reduction of O₂-Containing CO₂ Mixtures via Pt-Ni/CeO₂ Oxygen Carriers

Poor O₂ tolerance and high reaction temperature of the conventional oxygen carriers challenge the direct utilization of impure CO₂ via chemical looping. Here, Pt-Ni bimetallic Ce-based oxygen carriers with excellent O₂ tolerance are developed for highly efficient reduction of O2-containing CO₂ at low temperatures. At a temperature as low as 700 °C, high CO₂ conversion (≈92%) is obtained over 0.1 wt% Pt-0.1wt% Ni/CeO₂ oxygen carrier in the CO₂ feed gas with 16.7% O₂ impurities. These results benefit from that Pt-Ni bimetal plays a crucial role in improving CH₄ partial oxidation and accelerating the breaking of the C═O bond to alleviate the competitive oxidation of O₂ impurities. Ni compensates for the reduction of low-temperature redox activity caused by the decrease of Pt content. Moreover, Pt-Ni/CeO₂ oxygen carriers exhibit excellent structural and performance stability during redox cycles. This work presents a feasible strategy for the direct utilization of impure CO₂ at low temperatures and realizing a carbon-neutral cycle.