Mild hydrodeoxygenation of lignin-derived bio-oils to hydrocarbons over bifunctional ZrP2O7-Ni12P5 catalysts

An imperative current challenge for the production of renewable fuels is the development of efficient catalytic hydrodeoxygenation (HDO) of phenolic-rich bio-oils into hydrocarbons. In this work, a series of bifunctional ZrP2O7(x)-Ni12P5 (where × represents the molar ratio of Zr/Ni in the catalysts) catalysts were prepared for HDO of lignin-derived bio-oils (LBO). The characterization results show that among these bimetallic catalysts, ZrP2O7(0.4)-Ni12P5 possesses the largest specific surface area, pore volume and the highest amount of acid sites (Lewis and Brønsted) due to the introduction of appropriate amount of Zr species. Meanwhile, the interaction between Niδ+ and Zr species on its surface creates new active sites for the promotion on the hydrogen adsorption and activation, thus endowing the most excellent catalytic performance. Using the optimized catalyst of ZrP2O7(0.4)-Ni12P5, 95.8% cyclohexane yield could be obtained from the HDO of guaiacol as a model compound from bio-oil under mild condition (3 MPa H2 and 250 ℃). Moreover, 36.1% hydrocarbon yield is achieved from HDO of lignin-derived bio-oils (LBO) under the same hydrogen pressure and temperature. These findings not only open a novel avenue for designing a cost-effective metal–acid bifunctional catalyst, but also provide a viable approach for converting lignocellulosic biomass feedstocks into valuable hydrocarbons.