Water-enhanced selective hydrogenation of cinnamaldehyde to cinnamyl alcohol on RuSnB/CeO₂ catalysts

The CeO₂-supported ternary RuSnB catalysts were synthesized by incipient wetness impregnation procedures and applied in hydrogenation of cinnamaldehyde in pure water as the solvent. A synergy effect between Ru-based catalysts and water molecules has afforded the efficiently selective transformation of cinnamaldehyde to cinnamyl alcohol with the satisfactory conversion and selectivity. Structural characterization results suggested the incorporation of Ru sites into the SnO_x matrix and the electronic interaction between Ru and B additives in RuSnB/CeO₂ catalyst. The isotopic exchange studies have demonstrated that both dissociative activation of H₂ and H₂O (deuterated D₂ and D₂O) were apparently affected by the status of Ru sites. Furthermore, the kinetics tests in D₂O solvent have also revealed the co-existence of water-involved hydrogen-exchange route with the direct hydrogenation route using dissociative H₂ during the hydrogenation reaction. The optimal Ru₂Sn₁B₁/CeO₂ catalyst could afford the best H₂O-activation capability and thus accelerate the reaction rate in the H₂O-involved hydrogenation.