Background: Large amounts of enzymatic hydrolysis lignin (EHL) are generated with the production of cellulosic bioethanol. Efficient degradation and upgrading of EHL is significant for the sustainable and stable development of energy supply.
Results: In this study, hydrodeoxygenation (HDO) of EHL to biofuels was carried out promoted by the in situ hydrogen donor produced from the decomposition of formic acid over NiMo catalysts. Results showed that active sites (derived from the support SiO2, W, and NiMo species) had remarkable effect on lignin conversion, and the highest oil yield (57.2 wt%) was gained over NiMo/W-SiO2 catalyst.
Conclusions: The product evolution demonstrated that active metal sites (derived from NiMo species) favored hydrogenolysis and deoxygenation via leading in situ hydrogen to attack C-O-C bonds, while acid sites (derived from the support) adsorbed and activated chemical bonds in lignin, resulting in the linkage cleavage caused by the heating program. The obtained bio-oil was rich in alkyl guaiacols (6.7 wt%), containing stable chemical properties and high quality.