LAUSR

Carbon black‐supported ruthenium catalysts (Ru/C) with different Ru particle sizes and varying fractions of surficial RuO2 are prepared and studied for acetone hydrogenation. The size of Ru particles and the surficial RuO2 species on the Ru particles are found to affect the acetone conversion. Ru particles with larger size provide a higher catalytic activity suggesting an important role of particle size. Moreover, for Ru particles with larger sizes, the conversion decreases along with the increase of surficial RuO2 species fraction; however, an opposite trend is observed for cases with smaller Ru particles. Such distinguished catalytic acetone hydrogenation conversions for Ru/C with different particle sizes and varying surface RuO2 content suggest a size‐dependent synergetic effect, which, so far as we are concerned, is a new synergetic behavior between Ru and RuO2 in hydrogenation catalysis that has never been reported before. CO chemisorption, XRD, temperature‐programmed reduction, X‐ray photoelectron spectroscopy, and high‐resolution TEM are used to characterize the Ru particle sizes and the surficial RuO2 species.