Fe-promoted Ni nanocatalysts for hydrogenolysis of Klason lignin to monophenols

The efficient cleavage of lignin's inter-unit bonds is essential for its conversion into valuable monophenols. However, conventional Ni-based catalysts often suffer from poor metal dispersion, sintering, and limited catalytic activity. In this study, a series of bimetallic Ni₂M/Al₂O₃ (M = Fe/In/Mn/Cu/Co) catalysts were synthesized using layered double hydroxides as precursors. Among the metal promoters tested, Fe showed the highest efficacy in improving catalytic performance. Ni_xFe_y/Al₂O₃ catalysts with varying Ni/Fe molar ratios exhibited superior activity due to the formation of Ni-Fe alloys and defect-rich FeO_x species. The optimized Ni_1.5Fe_1.5/Al₂O₃ catalyst, characterized by well-dispersed small metal particles, strong Ni-Fe interactions, abundant surface oxygen vacancies, and a high density of strong acid sites, achieved a monophenol yield of 16.6 wt% from the hydrogenolysis of Klason lignin under mild reaction conditions (240 °C, 4 h, 1 MPa initial H₂). This work presents a novel approach for developing highly active bimetallic catalysts for lignin depolymerization, offering insights into the design of efficient catalysts for lignin valorization.