Lignin Quaternary\nAmmonium Phosphotungstate as a Recycle\nCatalyst for Oxidative Cleavage of Unsaturated Fatty Acids and Soybean\nOil

Using H<sub>2</sub>O<sub>2</sub> for oxidative cleavage\nof renewable\nunsaturated fatty acids (UFA) or plant oil is a green method for preparing\nbiobased mono- and dicarboxylic acids. However, due to the insolubility\nof UFA or oil in water, organic solvents or unrecyclable surfactants\nare usually needed to promote the contact between substrates and H<sub>2</sub>O<sub>2</sub>, which does not meet the Sustainable Development\nGoals. In this work, a series of lignin quaternary ammonium-supported\nphosphotungstate catalysts has been designed and prepared. Among these\ncatalysts, HPW-AL<sub>6500</sub>-QAS<sub>16</sub> showed the best\ncatalytic activity for the oxidative cleavage of oleic acid (OA) and\nsoybean oil (SBO) using H<sub>2</sub>O<sub>2</sub> as the oxidant\nwithout a solvent and additive. This lignin-based catalyst afforded\n100% OA and SBO conversion and up to 96.2% azelaic acid (AA), 94.6%\nnonanoic acid (NA) selectivities for OA and 91.8% AA, and 85.2% NA\nselectivities for SBO. More importantly, the lignin-based catalyst\ncould be easily recovered and reused at least 5 times without a significant\nloss in its catalytic activity. These characteristics make the oxidative\ncleavage of OA and SBO more efficient and environmentally friendly,\nwhich may be beneficial for industry applications.