Hydrodeoxygenation of heavy lignin bio-oil to oxygenated fuel catalyzed by CuxNiy/MgO

Novel techniques for upgrading heavy lignin bio-oil, the phenolic oligomer from lignin depolymerization, are of great significance for achieving better utilization efficiency of carbon element in lignin. In this study, we proposed an efficient approach for producing high-quality oxygen-containing fuel from the renewable lignin bio-oil via the C-O bond cleavage and the subsequent hydrogenation over the Cu and Ni supported on alkaline MgO. Noticeably, the optimized Cu6Ni20/MgO resulted in inspiring yields of ethylbenzene (88.6%) and cyclohexanol (98.3%) from lignin dimers, and a colorless fuel with a high-heating value of 31.4 MJ kg−1 from the realistic lignin bio-oil. The results of catalyst characterization also unveiled that introducing Cu species reduced the formation of NiMgOx solid solution, which increased the content of Ni0 and consequently promoted the performance of upgrading lignin bio-oil. Furthermore, the recondensation of phenolic oligomers could be effectively restrained by the alkaline MgO. In addition, a plausible mechanism was proposed. Therefore, this work opens a promising avenue to designing efficient strategies for utilizing the heavy components from lignin depolymerization.