| Abstract: | The extraction of metallic nanoparticles from perovskite-type oxides(ABO_3) under mild reducing conditions is a novel way to prepare well-dispersed supported catalysts(B/AOd). Herein, we found that the encapsulated PdO in perovskite LaCoO_3(PdO@LaCoO_3) could facilitate the phase transformation of the perovskite structure at a low temperature owing to both strong H2 spillover of Pd and intimate interaction between the encapsulated PdO and LaCoO_3. The pure LaCoO_3 without PdO was relatively inert to CO_2 hydrogenation(CO_2 conversion 4%). In contrast, PdO@LaCoO_3 exhibited excellent CO_2 methanation performance with 62.3% CO_2 conversion and 99% CH4 selectivity. The characterization results demonstrated that the catalytically active Co2 C was in-situ formed by carburization of the extracted Co0 during CO_2 methanation for the PdO@LaCoO_3 sample. Whereas, the LaCoO_3 with surface supported PdO(PdO/LaCoO_3) showed a weak interaction and remained a perovskite structure with few Co_2C active centers after the catalytic reaction, which was similar to the parent LaCoO_3. Accordingly, the PdO/LaCoO_3 showed an inferior catalytic performance with 31.8% CO_2 conversion and 87.4% CH_4 selectivity. Therefore, the designed encapsulation structure of PdO within perovskite is critical to extract metallic NPs from perovskite-type oxides, which has the potential to prepare other integrated nanocatalysts based on perovskite-type oxides. |
