Catalytic Conversion of Lignin and Lignin-Derived β-O-4 Ether to Cyclohexanols over a CeO2-Doped Carbon-Supported Nickel-Based Catalyst

In this study, a CeO2-doped carbon-supported nickel-based catalyst (Ni/XCeO2-C-Y) was synthesized and applied to the catalytic depolymerization of lignin and its derivatives. The variations in CeO2 content and calcination temperature are observed to cause a notable impact on the existence of oxygen vacancies. The results demonstrated that an optimal Ni/20%CeO2-C-500 exhibited excellent effectiveness in the cleavage of the beta-O-4 bond to ethylbenzene and cyclohexanol at 180 degrees C and 1 MPa N-2. In this system, isopropanol is used as a hydrogen-donating solvent as it can produce H-2 (detected by GC) during the reaction. The successful doping of CeO2 onto carbon contributes to the formation of an interaction between the carrier and nickel, causing a more uniform dispersion of metallic Ni. In addition, the selectivity of phenols in the real lignin depolymerization decreased from noncatalytic 71.5 to 25.4%, and most of the phenols were well converted into cyclohexanols and ketones. The reusability experiments revealed that Ni/20%CeO2-C-500 possessed excellent recycling and regeneration properties.