Green and highly selective hydrogenation of lignin-derived aromatics at low temperature over Ru-Fe bimetallic nanoparticles supported on porous nitrogen-doped carbon

Abstract

Low temperature and highly selective hydrogenation of the lignin-derived aromatics to obtain high-value chemicals and clean liquid fuels is a significant step for lignin valorization in the chemical industry. Developing efficient catalysts with high activity and selectivity for hydrogenation of lignin-derived aromatic rings at low temperature remains a big challenge. Herein, a well-dispersed Ru-Fe bimetallic nanoparticle catalyst supported on porous nitrogen-doped carbon was developed through a facile impregnation method. It showed excellent catalytic activity for hydrogenation of lignin-derived aromatics, such as diaryl ethers, phenolic monomers and arenes to corresponding alicyclic compounds with high selectivity, under surprisingly mild conditions (≤50 °C, ≤2 h and 1 MPa H2). Hydrogenation of aromatic rings took precedence over the cleavage of C-O bond for the lignin-derived aromatics. The resulting alicyclic compounds are key raw materials for synthesizing polymer, pharmaceutical intermediates and resins, and clean liquid fuels. The strong interactions between metal and support improved the anti-oxidation and anti-sintering ability of the catalyst, and significantly improve the hydrogenation performance. Additionally, the phenols in the lignin oil were effectively converted into cyclohexanol and its derivatives at 90 °C over the Ru-Fe bimetallic catalyst, with selectivity up to 53.3% in the hydrogenated lignin oil. The development of this catalyst for selective hydrogenation of lignin-derived aromatics at low temperature provides a green, low carbon footprint and sustainable approach for the value-added utilization of lignin and its derivatives.