Nb(Ta)-based solid acid modified Pt/CNTs catalysts for hydrodeoxygenation of lignin-derived compounds

Efficient upgrading of lignin bio-oils into oxygen-free liquid alkane fuels is a challenging task owing to the incompatibility of the phenolic feedstock with conventional fuels and the availability of effective hydrotreating catalysts based on the current refinery infrastructure. In this work, a series of solid acid nanosheets (HNbWO6, HNbMoO6, HTaWO6) modified Pt/CNTs bifunctional catalysts were evaluated in hydrodeoxygenation (HDO) of lignin-derived compounds. The effects of types of nanosheets and the synergistic effect between metal sites and acid sites were discussed via HDO of diphenyl ether. Pt/HNbWO6/CNTs catalyst exhibited the most efficient performance for the HDO of diphenyl ether to cyclohexane (conversion: 99.7%, selectivity: 96.4%) at 200 degrees C, 3.0 MPa. Several lignin aromatic model compounds including phenol, anisole, 2-phenylethyl phenyl ether and guaiacol were also investigated over Pt/HNbWO6/CNTs catalyst. Due to the different bond-dissociation energies of C-O bond and steric hindrance effect, guaiacol and phenol are more difficult to be converted than diphenyl ether and anisole based on the yield of cyclohexane. It was found that the Pt/HNbWO6/CNTs catalyst exhibited favorable stability. These results validated that it is desirable to utilize this catalyst in the HDO of actual lignin macromolecules into hydrocarbon fuels.