Boron nitride supported PtFe catalysts for selective hydrogenation of crotonaldehyde Original Research Article

The selective hydrogenation of crotonaldehyde was studied using boron nitride (BN) supported PtFe catalyst. A higher selectivity of crotyl alcohol than butyraldehyde was obtained, although butyraldehyde is thermodynamic favorable in the hydrogenation. The catalyst, PtFe/BN, was prepared by co-incipient wetness method. The metal loadings were 1.1 wt.% Pt and Fe ranging 0.1–0.6 wt.%. Commercial catalyst supports, graphite and γ-Al2O3, were also used to compare with BN. The higher iron content, the higher the crotyl alcohol selectivity was, while the activity was depressed. PtFe/γ-Al2O3 gave the lowest selectivity of crotyl alcohol. PtFe/graphite had the product selectivities similar to PtFe/BN, but its activity was lower than that of PtFe/BN. A maximum yield of crotyl alcohol was found at 0.2 wt.% Fe (molar ratio Fe/Pt = 0.64) on PtFe/BN catalysts at 100 °C. XRD revealed that PtFe alloy was formed on PtFe/BN during H2 reduction at 300 °C. The improvement of selectivity toward crotyl alcohol was attributed to the easier formation of PtFe alloy particle on BN surface than on γ-Al2O3. The Fe2+ on PtFe alloy polarizes the Cdouble bond; length as m-dashO bond of crotonaldehyde and the nearby Pto supplies the absorbed hydrogen to conduct the hydrogenation of the Cdouble bond; length as m-dashO bond, instead of the Cdouble bond; length as m-dashC bond. Therefore, both activity and the selectivity toward crotyl alcohol were enhanced appreciably.