Van Nguyen CBoo J.RLiu C.-HAhamad TAlshehri S.MMatsagar B.MWu K.C.-W.KEVIN CHIA-WEN WU2021-09-022021-09-02202020444753https://www.scopus.com/inward/record.uri?eid=2-s2.0-85081741750&doi=10.1039%2fc9cy02364j&partnerID=40&md5=09c83732193f0a2002ce863e62bc8985https://scholars.lib.ntu.edu.tw/handle/123456789/581559Maleic acid (MA) is a platform chemical used for synthesizing high-value polymers. Although MA can be produced from biomass-derived furfural, so far, only acidic catalysts have been proposed. Herein, for the first time, we report an acid-free furfural-to-MA conversion using nitrogen-doped carbon (NC) as an effective catalyst with the assistance of hydrogen peroxide (H2O2) as an oxidant. A high MA yield (61%) can be achieved over the NC-900 catalyst at 80 °C. The effects of reaction conditions, including H2O2 concentration, solvent type, reaction temperature, and time were systematically studied in detail and optimized. The ZIF-8-derived NC catalyst exhibited high activity owing to the existence of high graphitic nitrogen (N-Q) content in the carbon framework. The kinetics study indicates that the oxidation of furfural to MA over the NC-900 catalyst is via the formation of 5-hydroxy-furan-2(5H)-one as the main intermediate. Further, NC-900 can convert a variety of biomass-derived furan compounds to MA under acid-free conditions, indicating the versatility and applicability of the present acid-free, NC-based catalytic system. This journal is ? The Royal Society of Chemistry.Aldehydes; Aromatic compounds; Biomass; Carbon; Doping (additives); Furfural; Nitrogen; Organic pollutants; Reaction intermediates; Acid-free conditions; Acidic catalysts; Carbon framework; Kinetics studies; Nitrogen-doped carbons; Platform chemicals; Reaction conditions; Reaction temperature; Catalyst activity[SDGs]SDG12journal article10.1039/c9cy02364j