Pd/Nb2O5/SiO2 Catalyst for the Direct Hydrodeoxygenation of Biomass-Related Compounds to Liquid Alkanes under Mild Conditions

Graphical Mild mannered: Under mild conditions (170 °C, 2.5 MPa), Pd/10 %Nb 2 O 5 /SiO 2 is effective for the hydrodeoxygenation reactions of 4-(2-furyl)-3-buten-2-one (the aldol adduct of furfural with acetone), palmitic acid, tristearin, and diphenyl ether (model compounds of vegetable oils, microalgae oils, and lignin) and gives high yields (>94 %) of alkanes with little C  C bond cleavage. A simple Pd-loaded Nb 2 O 5 /SiO 2 catalyst was prepared for the hydrodeoxygenation of biomass-related compounds to alkanes under mild conditions. Niobium oxide dispersed in silica (Nb 2 O 5 /SiO 2 ) as the support was prepared by the sol–gel method and characterized by various techniques, including N 2 adsorption, XRD, NH 3 temperature-programmed desorption (TPD), TEM, and energy-dispersive X-ray spectroscopy (EDAX) atomic mapping. The characterization results showed that the niobium oxide species were amorphous and well dispersed in silica. Compared to commercial Nb 2 O 5 , Nb 2 O 5 /SiO 2 has significantly more active niobium oxide species exposed on the surface. Under mild conditions (170 °C, 2.5 MPa), Pd/10 %Nb 2 O 5 /SiO 2 was effective for the hydrodeoxygenation reactions of 4-(2-furyl)-3-buten-2-one (aldol adduct of furfural with acetone), palmitic acid, tristearin, and diphenyl ether (model compounds of microalgae oils, vegetable oils, and lignin), which gave high yields (>94 %) of alkanes with little C  C bond cleavage. More importantly, owing to the significant promotion effect of NbO x species on C  O bond cleavage and the mild reaction conditions, the C  C cleavage was considerably restrained, and the catalyst showed an excellent activity and stability for the hydrodeoxygenation of palmitic acid with almost no decrease in hexadecane yield (94–95 %) in a 150 h time-on-stream test.