Synergistic effects of Ni-Ni3P and Lewis-Brønsted acid for enhanced hydrodeoxygenation of phenolic compounds over Ni-Ni3P/ZrP

Catalytic hydrodeoxygenation (HDO) is an efficient and promising approach to upgrade lignin-derived phenolic compounds for the production of high-quality liquid fuels. In this work, a readily obtained Ni-Ni 3 P/ZrP catalyst featuring synergistic catalytic sites of Ni-Ni 3 P and Lewis-Brønsted acid was provided for promoting the HDO performance of lignin-derived phenolic compounds. By regulating the ratio of Zr to P (Zr/P), the catalytic activity of Ni/ZrP was significantly modified. With the optimized catalyst of Ni-Ni 3 P/ZrP-0.75, guaiacol is completely converted into cyclohexane at a low temperature of 240 °C. Further investigation shows that the synergistic effect of Ni and Ni 3 P, deriving from that Ni acts as metal site to activate hydrogen and Ni 3 P serves as Lewis acid site to adsorb guaiacol substrate, promotes the hydrogenation procedure significantly. Moreover, ZrP support as Lewis acid also demonstrates a synergistic interaction with Brønsted acid site that derives from the P-OH group. The coordination of Lewis-Brønsted acid site significantly improves the deoxygenation procedure. The strong interaction between Ni species and ZrP support accelerates the sequential occurrence of hydrogenation and deoxygenation procedures, thus improving the HDO efficiency. The Ni-Ni 3 P/ZrP-0.75 can be reused at least six runs without significant activity loss. Moreover, this Ni-Ni 3 P/ZrP-0.75 is efficient on the upgrading of realistic lignin-oil, with the hydrocarbon content increase from 13.4 % to 93.8 %. Therefore, this work provides a valuable reference for the rational design of bifunctional catalysts in the HDO reactions.