On the role of water in selective hydrogenation of cinnamaldehyde to cinnamyl alcohol on PtFe catalysts

A series of carbon nanotube (CNT)-supported bimetallic PtFe nanoparticles were synthesized and employed as catalysts for hydrogenation of cinnamaldehyde in pure water. A synergy between water and bimetallic PtFe catalysts has allowed the efficiently selective production of cinnamyl alcohol. With the aid of water, an initial reaction rate of >1200 h⁻¹ and a high selectivity of >97%, as well as a good cycling stability, were achieved with a Pt₃Fe/CNT catalyst under mild reaction conditions. Isotopic labeling studies and theoretic calculation results demonstrated that the water-involved hydrogen-exchange pathway occurred with a lower energy barrier, which coexisted with the pathway of direct H₂ dissociation–hydrogenation. This work also suggested that water participated in the catalytic hydrogenation reaction by serving as a hydrogen-exchange bridge.