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Ru/TiO2 catalysts exhibit an exceptionally high activity in the selective methanation of CO in CO2 - and H2 -rich reformates, but suffer from continuous deactivation during reaction. This limitation can be overcome through the fabrication of highly active and non-deactivating Ru/TiO2 catalysts by engineering the morphology of the TiO2 support. Using anatase TiO2 nanocrystals with mainly 001, 100, or 101 facets exposed, we show that after an initial activation period Ru/TiO2 -100 and Ru/TiO2 -101 are very stable, while Ru/TiO2 -001 deactivates continuously. Employing different operando/in situ spectroscopies and ex situ characterizations, we show that differences in the catalytic stability are related to differences in the metal-support interactions (MSIs). The stronger MSIs on the defect-rich TiO2 -100 and TiO2 -101 supports stabilize flat Ru nanoparticles, while on TiO2 -001 hemispherical particles develop. The former MSIs also lead to electronic modifications of Ru surface atoms, reflected by the stronger bonding of adsorbed CO on those catalysts than on Ru/TiO2 -001.
Chen et al. (Thu,) studied this question.