Strong Metal-Support Interaction (SMSI) effect, which often happens upon thermal treatment of supported metal catalysts at high temperatures (³ 500 °C), is one of the most important concepts in heterogeneous catalysis. It is usually used to explain the morphology evolution and catalytic mechanism at the interfaces between metal and active oxide supports.
Recently, a research team led by Prof. Qiang Fu and Prof. Xinhe Bao from the Dalian Institute of Chemical Physics (DICP) of the Chinese Academy of Sciences (CAS) found that this SMSI state can be constructed in a Ru-MoO3 catalyst by CO2 hydrogenation reaction gas and at low temperature of 250°C, which favors the selective CO2 hydrogenation to CO. This work was published in Journal of the American Chemical Society on March 8, 2022. (Article link: https://pubs.acs.org/doi/full/10.1021/jacs.1c12603)
The mixed metal oxide catalyst, 1.9 wt% Ru-Mo-Ox, was directly evaluated in CO2 hydrogenation reaction without pre-reduction. During the reaction Ru nanoparticles facilitate reduction of MoO3 to generate active MoO3-x(0<x<1) overlayers due to H-spillover, then migrating onto Ru nanoparticles and forming the encapsulated structure of Ru@MoO3-x. The formed SMSI state changes 100% CH4 selectivity on the fresh Ru particle surfaces to above 99.0%CO selectivity with excellent activity. The encapsulating oxide layers can be removed via O2 treatment, switching back completely to the methanation reaction. Besides, the interface confinement between encapsulating Mo oxide overlayers and Ru NPs helps to stabilize the defective
MoO3-x surface phase, having high reactivity and long-term stability under the reaction conditions. This work suggests that the encapsulation of metal nanocatalysts can be dynamically generated in real reactions which helps to gain the target products with high activity.
This work was financially supported by National Natural Science Foundation of China (No. 21825203, No. 21688102, and No. 91945302), Strategic Priority Research Program of the Chinese Academy of Sciences (Grant No. XDB17020000), LiaoNing Revitalization Talents Program (XLYC1902117), and the Dalian National Laboratory for Clean Energy (DNL) Cooperation Fund (DNL201907). (Text/image by Hui Xin)