Oxidation of 5-[(Formyloxy)methyl]furfural to Maleic Anhydride with Atmospheric Oxygen Using α-MnO<sub>2</sub>/Cu(NO<sub>3</sub>)<sub>2</sub> as Catalysts
Wenlong Jia, Zhihao Si, Yunchao Feng, Xin Zhang, Xiaoyu Zhao, Yong Sun, Xing Tang, Xianhai Zeng, Lu Lin
Abstract
A novel approach to produce renewable maleic anhydride (MA) from bio-based platform chemical 5-[(formyloxy)methyl]furfural (FMF) was developed with air or pure oxygen at atmospheric pressure using α-MnO2/Cu(NO3)2 as catalysts with the assistance of K2S2O8. The synergy of α-MnO2/Cu(NO3)2 ensured a high yield of MA through a MnIV/MnII redox couple facilitated by redox cycle of CuII/CuI and NO3–/NO2/NO with the assistance of O2. In this oxidation, FMF was first oxidized to 2,5-diformylfuran (DFF), as an intermediate, and then DFF underwent oxidation decarbonylation, hydration, and 1,4-rearrangement to form 5-hydroxyl-2(5H)-furan-one, followed by the oxidation to MA. Compared with the MA yield of less than 45% from the oxidation of 5-hydroxymethylfurfural, FMF showed a higher oxidation efficiency than MA with a yield of up to 89% under mild conditions.