Visible-Light-Driven Furfural Oxidation over CuOx /Nb2 O5

Maleic anhydride (MA) is an important polyester monomer that can be produced from oxidizing renewable furfural derived from biomass. However, MA generation from furfural requires harsh reaction conditions, and suffers from low efficiency and solvent corrosion. Herein, we design a Nb2 O5 photocatalyst loaded of highly dispersed CuOx (CuOx /Nb2 O5 ), which selectively catalyzes furfural oxidation to MA and the precursor (5-hydroxy-2(5H)-furanone, HF). Due to CuOx loading and forming a complex of ligand to metal charge transfer (LMCT) between the Nb2 O5 surface and adsorbed furfural, the CuOx /Nb2 O5 absorbs visible light to activate furfural though Nb2 O5 has a large band-gap energy (3.2 eV). Singlet oxygen (1 O2 ) is the key active species for C-C bond cleavage and CO generation. MA and HF is produced with a combined yield of 59 % under optimized conditions. This work provides a mild way to provide renewable maleic anhydride via oxidative C-C bond cleavage.