Highly selective catalytic transfer hydrodeoxygenation of lignin-derived phenols over carbon-encapsulated cobalt catalyst

Abstract

The catalytic transfer hydrodeoxygenation (CTHDO) technology of lignin-derived bio-oil is a very promising bio-oil conversion technology. However, the preparation of highly active and stable catalysts remains a major challenge. Carbon-coated metal nanoparticle catalysts can effectively solve the problems of catalyst deactivation and high-temperature metal leaching. In this work, a series of MOF-derived carbon-coated Co-based catalysts were designed via a simple solvothermal method using terephthalic acid as organic ligands, which were applied for the CTHDO reaction of guaiacol using isopropanol as H-donor. Among them, Co/C-2-500 had the best catalytic performance for the conversion of lignin-derived phenol to cyclohexanol. Under the optimal conditions of 180 °C, 0.5 MPa N₂, and 3 h, the conversion rate of guaiacol can reach 100 %, and the yield of cyclohexanol can reach 96.8 %. Mechanism research showed that the phenol generated from the demethoxylation of guaiacol was a key intermediate, which further underwent the hydrogenation of aromatic ring to form cyclohexanol. Based on the various characterizations, it can be considered that the high catalytic activity was due to the synergistic effect of the metallic Co⁰ active sites and the acid sites. This research could provide some insights for the catalytic transfer hydrodeoxygenation of lignin and its derivatives.