New Strategy for Migration Enhances CO2 Reduction to CO

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Researchers from the Dalian Institute of Chemical Physics (DICP) at the Chinese Academy of Sciences (CAS) have proposed a new migration strategy that boosts carbon dioxide (CO2) reduction to carbon monoxide (CO) through a reverse water-gas shift reaction. This innovative approach involves the selective migration of titanium dioxide (TiO2) to a second oxide support instead of the surface of metal nanoparticles (NPs) in Ru/(TiOx)MnO catalysts.

Traditional strong metal-support interaction (SMSI) theory explains how a reducible oxide migrates to the surface of metal NPs during high-temperature hydrogen (H2) thermal treatment, resulting in a metal@oxide encapsulation structure that offers high selectivity and stability. However, this encapsulation structure hinders the adsorption and dissociation of reactant molecules, particularly H2, over the metal, leading to low activity, especially in hydrogenation reactions.

To overcome this limitation, the research team led by Prof. Liu Yuefeng achieved controlled migration by utilizing the strong interaction between TiO2 and manganese oxide (MnO) in Ru/(TiOx)MnO catalysts during H2 thermal treatment. By doing so, TiO2 spontaneously re-dispersed on the MnO surface, preventing the formation of a TiOx shell on the Ru NPs for the Ru/TiOx/MnO ternary catalyst.

The migration of activated H species from metal Ru to the support was enhanced due to the high-density titanium oxide/manganese oxide interfaces generated during the process. These interfaces acted as a highly efficient hydrogen transportation channel with a low barrier, facilitating H-spillover and subsequent reactions. As a result, the Ru/TiOx/MnO catalyst demonstrated 3.3-fold higher catalytic activity for CO2 reduction to CO compared to a Ru/MnO catalyst. The preparation of the titanium/manganese support was not impacted by crystalline structure and grain size of TiO2 nanoparticles. Even the mechanical mixing of Ru/TiO2 and Ru/MnOx improved the catalyst’s activity.

Additionally, the researchers confirmed that the synergistic effect of TiO2 and MnO did not alter the intrinsic catalytic performance, and the efficient hydrogen transport provided numerous active sites (hydroxyl groups) for the reaction process.

These findings have significant implications for the design of novel selective hydrogenation catalysts by creating oxide-oxide interfaces that act as hydrogen species transport channels. This new strategy provides valuable references for future research and development in this area.

 

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  1. Source: Coherent Market Insights, Public sources, Desk research
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