Fabricating high temperature stable Mo-Co9S8/Al2O3 catalyst for selective hydrodeoxygenation of lignin to arenes

Achieving high-temperature stability/duration without compromising the activity remains an arduous task in catalyst design, particularly for MoS2 materials. Herein, a robust catalyst with Mo doped Co9S8 nanoparticles anchored on Al2O3 matrix is fabricated, which could selectively convert lignin to arenes with high hydrodeoxygenation activity, selectivity and particularly excellent stability. In the hydrodeoxygenation of diphenyl ether, this catalyst afforded 99.8% conversion and 91.0% yield of benzene at 265 °C for at least 10 reaction runs. The resultant Mo-Co9S8 structure with chemical connection by covalent bonds of Mo-S-Co type on the Co9S8 surface demonstrates strong ability in the adsorption and activation of oxygen-containing substrates, which enables the effective C-O cleavage whilst avoids undesirable hydrogenation of benzene ring. The superior stability and water-resistance at elevated temperature was attributed to the anchoring effect of Al2O3 matrix and “protection” of surface-rich Co9S8 species to the active Mo-Co9S8 center. This strategy provides new sights for the rational design of efficient and stable sulfide catalysts towards the applications in demanding high-temperature reactions.