Hydrodeoxygenation of lignin derived bio-oil into aromatic hydrocarbons over Ni-Cu-Ru/HZSM-5 catalyst

The complexity and diversity of lignin derived bio-oil (LDB) has posed a great challenge to the subsequent processing and utilization. In this work, HZSM-5 was modified by sodium hydroxide and followed by Ni, Cu and Ru species. LDB was used as the raw biocrude to prepare bio-oil rich in aromatic hydrocarbons with modified HZSM-5 catalysts under supercritical ethanol conditions (320 °C, 14 MPa). Results showed that the desilicated HZSM-5 with the loading of Ni, Cu and Ru (Ni-Cu-Ru/DeHZSM-5) exhibited the best catalytic performance with a high relative amount of aromatic hydrocarbons of 28.95%. After catalytic hydrodeoxygenation (HDO) of LDB, 80.40% upgraded bio-oil (UBO) with 96.32% energy recovery was obtained in the presence of Ni-Cu-Ru/DeHZSM-5. Demethoxylation and dehydration were the main reactions in the catalytic HDO process. Potential reaction pathways of guaiacol, syringol and creosol were also proposed in this paper. The heating value of UBO reached 35.22 MJ/kg compared with LDB, which was increased by 19.80%. The water content and viscosity of UBO were also significantly improved. The micro-mesoporous structure of modified HZSM-5 with loading of Ni, Cu and Ru was beneficial to promote the yield of the aromatic hydrocarbons.