Kinetic study of selective hydrogenation of crotonaldehyde over Fe-promoted Ir/BN catalysts

A series of FeO_x-promoted Ir/BN catalysts were tested for gas phase selective hydrogenation of crotonaldehyde. The addition of FeO_x in the catalyst greatly improves the performance, up to a 5-fold enhanced steady state crotyl alcohol yield (46.9%) compared to that of the bare Ir/BN (7.2%). The characterization results reveal that the Ir-FeO_x interaction results in the generation of new active sites at the interface, which are responsible for the enhanced performance. The kinetic study showed that the Ir-FeO_x interfacial active site has much higher turnover frequency (82.9 × 10⁻³ s⁻¹) than the Ir⁰-Ir^δ+ site in the Ir/BN catalyst (3.10 × 10⁻³ s⁻¹), due to the promotion of FeO_x leads to a higher intrinsic rate constant (12.1 × 10⁻⁷ v.s. 1.19 × 10⁻⁷ mol g⁻¹ s⁻¹) and a higher adsorption equilibrium constant of crotonaldehyde (3.49 v.s. 0.62 kPa⁻¹).