Lignin Valorization by Cobalt‐Catalyzed Fractionation of Lignocellulose to Yield Monophenolic Compounds

• Published in: ChemSusChem 2019-01, Vol.12 (2), p.404-408
• Main Authors: Rautiainen, Sari, Di Francesco, Davide, Katea, Sarmad Naim, Westin, Gunnar, Tungasmita, Duangamol N., Samec, Joseph S. M.
• Format: Article
• Language: English
• Subjects: biomass fractionation; birch wood; Catalysis; Catalysts; cobalt; Cobalt compounds; Depolymerization; Formic acid; Fractionation; Green & Sustainable Science & Technology; heterogeneous catalysis; Hydrogen storage; Hydrogenolysis; Lignin; Lignocellulose; Pulping
• ISSN: 1864-5631; 1864-564X; 1864-564X
• DOI: 10.1002/cssc.201802497

Herein, a catalytic reductive fractionation of lignocellulose is presented using a heterogeneous cobalt catalyst and formic acid or formate as a hydrogen donor. The catalytic reductive fractionation of untreated birch wood yields monophenolic compounds in up to 34 wt % yield of total lignin, which corresponds to 76 % of the theoretical maximum yield. Model compound studies revealed that the main role of the cobalt catalyst is to stabilize the reactive intermediates formed during the organosolv pulping by transfer hydrogenation and hydrogenolysis reactions. Additionally, the cobalt catalyst is responsible for depolymerization reactions of lignin fragments through transfer hydrogenolysis reactions, which target the β‐O‐4′ bond. The catalyst could be recycled three times with only negligible decrease in efficiency, showing the robustness of the system. Efficient valorization of lignin using Co‐based catalyst: A cobalt‐based heterogeneous catalyst is proposed for valorization of lignin directly from lignocellulose. Formic acid or formate is used as a hydrogen donor on untreated birch wood to produce monophenolic compounds with a high selectivity with respect to lignin. The catalyst shows high reproducibility with negligible decline in efficiency even after three cycles.