The influence of CeO2 different morphologies effects on hydrodeoxygenation for guaiacol on Ni/CeO2 catalysts

Catalytic hydrodeoxygenation (HDO) is an effective way to produce high–value products from lignin-derived phenolic compounds. In this work, three different morphologies of Ni/CeO2 catalysts (amorphous, cubic, and rod-shaped) have been prepared through the conventional wet impregnation method. They can be used for the HDO of guaiacol to prepare cyclohexanol, an important chemical raw material. The influence of different morphologies of CeO2 on catalytic activity was explored. The research results indicate that Ni/CeO2–r catalysts with rod-shaped structures exhibit excellent catalytic properties. As a result, a 100 % conversion rate and 96.9 % cyclohexanol yield were achieved on the Ni/CeO2–r catalyst at 240 °C. The catalytic performance of the three catalysts follows this order: Ni/CeO2–r (rod-shaped) > Ni/CeO2–c (cubic) > Ni/CeO2–p (amorphous). The results of Raman and XPS indicate significant differences in the surface oxygen vacancy in catalysts with different morphologies. The Ni/CeO2–r catalyst has the highest oxygen vacancy concentration and defect. In addition, Ni/CeO2–r also has the largest specific surface area (SBET) and the highest nickel dispersion, and forms more Ni0 because of the strong interaction of Ni species and CeO2 support. Therefore, Ni/CeO2–r exhibits the most excellent catalytic performance for the hydrogenation of guaiacol than the other two catalysts. Moreover, the cycling activity test was also investigated over the Ni/CeO2–r catalyst. After five cycles, the conversion rate of guaiacol and the yield of cyclohexanol hardly decrease. This work provides vital ideas for the development of higher-activity, higher-stability, and low-cost catalysts for the conversion of lignin-derived phenolic compounds in the future.