Promotional effect of F for Pd/HZSM-5 catalyst on selective HDO of biobased ketones

In this work, fluorine-enhanced Pd/HZSM-5 catalyst was synthesized for selective hydrodeoxygenation of biomass derived ketones by using polymethylhydrosiloxane (PMHS) as the hydrogen source under mild conditions. According to characterizations, the highly electronegative F can replace the OH group on the HZSM-5 to form a special F-Al structure over the Pd/HZSM-5 catalyst, thereby the surface morphology, hydrophobicity, acidity and electronic character of Pd/HZSM-5 catalyst can be regulated by the amount of fluorine doping. The Pd-F/HZSM-5(5) catalyst with F-doping at 5 wt% exhibited the best catalytic activity and water-resistance for acetophenone hydrodeoxygenation among a series of Pd-based catalysts, achieving >99% yield and 93.7% yield toward ethylbenzene at 65 °C for 3 h in ethanol and in 95 vt% ethanol, respectively. The F-Al structure formed by the F modification replaces the -OH on the HZSM-5, which inhibited the adsorption to water on the metal active site of the catalyst, thus effectively improving the catalytic performance for selective hydrodeoxygenation of biomass-derived ketones. In addition, the as-prepared Pd-F/HZSM-5(5) catalyst with an excellent circulation capability after 5 times use, and the >90% yield of deoxidation production can be obtained for the HDO of various biomass-derived ketones.