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

Poor O-2 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 O-2 tolerance are developed for highly efficient reduction of O-2-containing CO2 at low temperatures. At a temperature as low as 700 degrees C, high CO2 conversion (approximate to 92%) is obtained over 0.1 wt% Pt-0.1wt% Ni/CeO2 oxygen carrier in the CO2 feed gas with 16.7% O-2 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 O-2 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.