Co-Mn bimetallic oxide catalyzed continuously ozonation of lignin to high-value added aromatic aldehydes under mild condition

Lignin, as a typical potential agriculture residual, was continuously and efficiently converted to high value-added aromatic aldehydes by a cobalt-manganese bimetallic oxide (CMO) catalyzed ozonation under mild condition. Comparing with Co 3 O 4 and Mn 3 O 4 nanoparticles, CMO showed excellent redox ability due to the oxygen vacancies (O v ), which further caused remarkable catalytic lignin conversion performance. The catalytic ozonation depolymerization efficient for corn cob lignin under the presence of CMO was 42.3 % higher than that of single ozonation. 2D HSQC NMR showed both the lignin-carbohydrate complexes and β-O-4 bond in lignin were depolymerized efficiently under the CMO catalyzed ozonation. By employing Electron Paramagnetic Resonance spectroscopy (EPR), the superoxide radical by the ozone decomposing on the surface of CMO was detected, which further caused the β-O-4 bond cleaving. Furthermore, by employing on-line Fourier Transform Infrared Spectrometer (on-line FTIR) spectrum, the lignin-carbohydrate complexes and β-O-4 bond cleaving during lignin depolymerization process were investigated. Thus, this study introduced a novel insight for highly-efficient convert biomass to high value-added compounds, which has potential applications in the production of materials and chemicals. Lignin was continuously and efficiently converted into high value-added aromatic aldehydes by a cobalt-manganese bimetallic oxide (CMO) catalytic ozonation under continuous flow. • Lignin was continuously converted to high value-added aromatic aldehydes by a cobalt-manganese bimetallic oxide (CMO). • The total yield of aromatic monomers reached ∼14 wt% under the catalytic of CMO. • The CMO catalyzed corn cob lignin ozonation efficient was 42.3 % higher than that of single ozonation. • The superoxide radical by the ozone decomposing caused the β-O-4 bond cleaving.