Low-Temperature and Highly Efficient Reduction of O 2 -Containing CO 2 Mixtures via Pt-Ni/CeO 2 Oxygen Carriers.

Poor O ₂ tolerance and high reaction temperature of the conventional oxygen carriers challenge the direct utilization of impure CO ₂ 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 CO ₂ at low temperatures. At a temperature as low as 700 °C, high CO ₂ conversion (≈92%) is obtained over 0.1 wt% Pt-0.1wt% Ni/CeO ₂ oxygen carrier in the CO ₂ feed gas with 16.7% O ₂ impurities. These results benefit from that Pt-Ni bimetal plays a crucial role in improving CH ₄ 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/CeO ₂ oxygen carriers exhibit excellent structural and performance stability during redox cycles. This work presents a feasible strategy for the direct utilization of impure CO ₂ at low temperatures and realizing a carbon-neutral cycle.
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