Efficient conversion of lignin to alkylphenols over highly stable inverse spinel MnFe2O4 catalysts

The aromatic properties of lignin make it a promising source of valuable chemicals and fuels. Developing efficient and stable catalysts to effectively convert lignin into high-value chemicals is challenging. In this work, MnFe 2 O 4 spinel catalysts with oxygen-rich vacancies and porous distribution were synthesized by a simple solvothermal process and used to catalyze the depolymerization of lignin in an isopropanol solvent system. The specific surface area was 110.5 m 2 ·g −1 , which substantially increased the active sites for lignin depolymerization compared to Fe 3 O 4 . The conversion of lignin reached 94%, and the selectivity of alkylphenols exceeded 90% after 5 h at 250 °C. Underpinned by characterizations, products, and density functional theory analysis, the results showed that the catalytic performance of MnFe 2 O 4 was attributed to the composition of Mn and Fe with strong Mn-O-Fe synergy. In addition, the cycling experiments and characterization showed that the depolymerized lignin on MnFe 2 O 4 has excellent cycling stability. Thus, our work provides valuable insights into the mechanism of lignin catalytic depolymerization and paves the way for the industrial-scale application of this process.