Shape dependency of CO₂ hydrogenation on ceria supported singly dispersed Ru catalysts

Harnessing the selectivity in catalytic hydrogenation of CO2 is important for producing valuable chemicals. Herein, the shape dependency of the CO2 hydrogenation on singly dispersed Ru/CeO2 catalysts is investigated. CeO2 of three shapes, including nanocube, nanooctahedron and nanorod, are prepared as the catalyst supports and assigned to the surface of (100), (111) and (110) crystal plane, respectively. The Ru/CeO2 (nanorod) exhibits the highest selectivity to CO (97.6 %) at 350 degrees C, while the Ru/CeO2 (nanocube) exhibits a mediocre selectivity to CO (41.4 %) but the highest CO2 conversion. The shape of the CeO2 support determines the electronic state of supported Ru atoms through the electronic metal-support interaction. The low CO affinity on cationic Ru-beta sites leads to the higher selectivity to CO on the Ru/CeO2 (nanorod) and Ru/CeO2 (nanooctahedron) catalysts, while the strong dissociation ability of H-2 on low valence Ru-alpha sites results in the high activity on the Ru/CeO2 (nanocube) catalyst.