Efficient Hydrodeoxygenation of Lignin-Derived Phenols to C6+ Cycloalkanols/Cycloalkanes over Magnetic Carbon-Encapsulated Nickel Nanospheres

To obtain value-added fuels and chemicals from lignin, it is necessary to explore an efficient catalytic system for hydrodeoxygenation (HDO). In this study, a highly efficient and magnetically separable Ni@C catalyst was synthesized for conversion of lignin-derived phenols. Detailed results showed that the pyrolysis temperature played a crucial role in the difference of the carbon-defect degree, which increased the metal dispersion and the strong electronic metal–support interactions. Meanwhile, we revealed that the differentiated pyrolysis temperature induced the appropriate presence of Ni2+ as Lewis acid sites and Niδ+ as heterohydrogen cleavage sites, which provided an acceleration effect for the HDO reaction. The results displayed that higher reactivity of lignin-derived phenols into C6+ cycloalkanols was achieved over the Ni@C catalyst (100% conversion and 87.19% selectivity). Moreover, the high selectivity of C6+ cycloalkanes was achieved after adding H-ZSM-5 as Brønsted acid sites (100% conversion and 100% selectivity). This investigated work offers an efficient strategy for conversion of lignin-derived aromatics into value-added chemicals.