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 SnOx 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 H-2 and H2O (deuterated D-2 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 H-2 during the hydrogenation reaction. The optimal Ru2Sn1Bi1/CeO2 catalyst could afford the best H2O-activation capability and thus accelerate the reaction rate in the H2O involved hydrogenation.