"Cocktail"-type catalysis on bimetallic systems for cinnamaldehyde selective hydrogenation: Role of isolated single atoms, nanoparticles and single atom alloys

Reaching high selectivity at high conversion and high rate in the industrially important selective hydrogenation of a,b-unsaturated aldehydes is a challenging task. Among current approaches reported in the literature, high selectivity towards the unsaturated alcohol or saturated aldehyde is generally achieved at the expense of activity. The use of bimetallic systems can lead either to selectivity or to activity enhancement, but generally not to both. Herein, we show that, for cinnamaldehyde hydrogenation, combining Ni nanoparticles (NiNP) and Ru single atoms (RuSA) on CNTs allows improvement of the hydrocinnamaldehyde selectivity, while obtaining a remarkable activity. The STY of RuSA-NiNP/CNT is approximately 60 times higher than that of the RuSA/CNT and 10 times higher than that of the NiNP/CNT. Importantly, the resulting catalyst shows 94% selectivity at 99% conversion and a good stability in flow. Insights into the cooperative "cocktail"-type catalysis between NiNP and RuSA were revealed from density functional theory calculations.