Enhanced Hydroconversion of Lignin-Derived Oxygen-Containing Compounds Over Bulk Nickel Catalysts Though Nb₂O₅ Modification

Abstract

A series of bimetallic Nb–Ni oxide catalysts with different Nb/Ni molar ratio have been prepared by chemical precipitation method. XRD, Raman and XPS results indicate that amorphous Nb₂O₅ species exist in the samples with a Nb/Ni ratio about 0.087. The as-synthesized bimetallic Nb–Ni oxides effectively promote the dispersion of NiO active components, as a result effectively inhibit the agglomeration of NiO particles. Ni_0.92Nb_0.08O sample with the largest surface area of 173 m²/g mainly consists of fold-like nanosheets and the amorphous Nb₂O₅ species are well-dispersed all over the bulk NiO. After the reduction in hydrogen, the Nb-promoted bulk nickel catalysts display better catalytic performance for hydrodeoxygenation of lignin-derived anisole to biofuels than bulk Ni catalyst. The selectivity to deoxygenated products with using Ni_0.92Nb_0.08 catalyst increases 2.5 fold to that with bulk Ni catalyst at 160 °C and 3 MPa H₂, as a result of the synergistic effect between amorphous Nb₂O₅ species and metal Ni active sites. In addition, with further increase in the reaction temperature to 200 °C, deoxygenation almost goes quantitatively.

Graphical Abstract

High-specific-surface-area Nb–Ni oxides are prepared by using chemical precipitation, and display excellent HDO performance for lignin-derived compounds. Selectivity to deoxygenated products increases 2.5 folds over Ni_0.92Nb_0.08 than over bulk Ni catalyst.