A biomass-derived metal-free catalyst doped with phosphorus for highly efficient and selective oxidation of furfural into maleic acid

Abstract

The present work introduces an extremely simple and eco-friendly strategy for the highly selective synthesis of maleic acid (MA) via oxidation of renewable furfural using the abundant biomass-derived P–C-T catalyst. The P–C-T carbon catalyst was metal-free and prepared by the pyrolyzation of phytic acid, which is a ubiquitous natural molecule containing phosphorus. Extensive characterization was carried out to reveal the morphological and elemental properties of the synthesized P–C-T series. The effect of the annealing temperature of pyrolyzing phytic acid on the properties of the yielded P–C-T and subsequent catalytic performance was also explored. The catalytic oxidation of furfural to MA was carried out in the presence of H₂O₂ within an aqueous system. The reaction conditions including the catalyst loading, H₂O₂ concentration, reaction temperature and duration were further optimized. It was found that P–C-600 exhibited a remarkable catalytic activity for MA synthesis from furfural oxidation with a maximum yield of 76.3% achieved in water. The excellent catalytic performance of P–C-600 was attributed to its unique atomic layered structure and suitable acidity. P–C-600 could also be re-used for at least six runs without any obvious decrease in its catalytic performance. The intrinsic advantages of green synthesis, low cost, and excellent catalytic performance in the catalytic oxidation of furfural to MA suggested that P–C-600 would be a promising catalyst in future industrial applications for MA synthesis in a green manner.