A novel BN supported bi-metal catalyst for selective hydrogenation of crotonaldehyde Original Research Article

A series of boron nitride (BN) supported Pt-Sn catalysts was prepared with a co-incipient wetness method employing hexachloroplatinic acid and tin(II) chloride. Pt loading was fixed at 1.1 wt%; Sn loading varied from 0.25 to 0.75 wt% on BN support. Selective hydrogenation of gas-phase crotonaldehyde was conducted in a steady-state flow reactor with temperatures ranging from 40 to 100 °C. The selectivity of crotyl alcohol reached over 80%. An optimum yield of crotyl alcohol reached 38% at 60% conversion of crotonaldehyde at 80 °C using Pt-Sn(0.75)/BN catalyst, while Pt-Sn(0.75)/γ-Al2O3 yielded less crotyl alcohol and a lower rate of crotonaldehyde conversion. The maximum yield rate of crotyl alcohol was 2.4 mmol/(g-cat. h) at 80 °C. Negligible deactivation was found during reaction for 4–6 h. The crystalline phases of PtSn and SnPt3 alloys were observed from the XRD spectra of Pt-Sn/BN catalysts with various Sn loadings. The selectivity of crotyl alcohol increased with Sn loadings but the activity values of the catalysts went through a maximum. The H2 reduction at 300 °C gave an optimum Pt–Sn alloy particle size so that the selectivity of crotyl alcohol increased without losing catalyst activity. The Cdouble bond; length as m-dashO bond of crotonaldehyde was preferentially hydrogenated and the hydrogenation of Cdouble bond; length as m-dashC bond was suppressed, resulting in the increase of crotyl alcohol selectivity.