Synergistic regulation of acid sites and metal sites on MOF-Derived FeNi-NC catalysts for microwave-assisted lignin hydrogenolysis

Constructing catalysts with synergistic effect of acid and metallic sites is crucial for efficient hydrogenolysis of lignin but challenging. Herein, a FeNi bimetallic catalyst was synthesized using metal–organic frameworks (MOF) as precursor, with N-doping and acid etching employed to tailor the surface acid sites. Capitalizing on the superior microwave absorption capability of the catalyst, microwave irradiation was integrated to drive the hydrogenolysis process. The impact of acid sites on catalyst performance was first evaluated, followed by a systematic investigation of the synergistic interplay between acid and bimetallic sites in regulating the reaction pathway, through a combination of hydrogenolysis experiments and density functional theory (DFT) calculations. The findings demonstrate that acid sites cooperate with Fe to facilitate the selective cleavage of C-O bonds, whereas Ni primarily governs the generation and activation of hydrogen radicals for the hydrogenation of intermediates into phenol. This microwave-assisted catalytic strategy achieved a substantial enhancement on the phenol production with the phenol yield of 18.6 wt%, offering new perspectives for the design of multi-sites synergistic catalysts to advance the targeted depolymerization of lignin.