Enhanced Selective Oxidation of Glycerol to Dihydroxyacetone over Pt@Sn-MFI Zeolites

Supported Pt nanoparticles (NPs) exhibit excellent activity for the selective oxidation of glycerol (GL) derived from biodiesel production to high-value dihydroxyacetone (DHA). However, their selectivity to DHA is not satisfactory due to the preferential oxidation of the primary −OH in GL. In this study, Pt@Sn-MFI with ∼4.0 nm Pt NPs and different Si/Sn ratios were synthesized by an in situ encapsulation strategy. The optimized Pt@Sn-MFI-80 catalyst presents a 74.8% selectivity to DHA with a GL conversion of 43.5% at 60 °C. Our experiments and density functional theory (DFT) calculations indicated that the excellent selectivity was ascribed to the synergistic effect between Pt and Sn-MFI. Sn-MFI turned Pt NPs into an electronic-poor state so that suppressed further oxidation of glyceraldehyde (GLD); then, Sn-MFI triggered isomerization of GLD to generate DHA. The core–shell structure not only guaranteed an intimate contact between Pt and Sn-MFI but also enhanced the stability of the active Pt NPs.