Heterogeneous catalytic oxidation of furfural with hydrogen peroxide over a niobia catalyst†

Furfural is a very interesting bio-based platform molecule that can be derived from the pentoses found in hemicelluloses, such as xylose and arabinose. Furfural displays significant potential as a source for the production of various chemicals. By oxidizing furfural with hydrogen peroxide, a range of products can be obtained, including diacids such as succinic and maleic acids, as well as lactones such as 2(5H)-furanone. In this study, the oxidation of furfural was conducted using niobia as a heterogeneous catalyst, which displayed an interesting behavior, giving 2,3-dihydroxybutanedioic acid (tartaric acid) as the main oxidation product. Other typical oxidation products, namely succinic acid and 2(5H)-furanone were also obtained in moderate concentrations. Tartaric acid and the rest of the oxidation products were identified by GS-MS, ¹H NMR and ¹³C NMR. A wide range of conditions were screened to reveal the catalytic behavior of the system, enabling furfural consumption and formation of tartaric acid. Additionally, a plausible reaction network was established based on a previously proposed mechanism and experimental observations that accounted for the production of tartaric acid.