Polymer Monomers Fabricated from Biomass Platform Molecules over Metal-free Catalysts

Developing new catalytic methods in the effective syntheses of 2,5-furandicarboxylic acid (FDCA) and glycolic acid (GA) through the selective oxidation of biomass-derived 5-hydroxymethylfurfural (HMF) and 1,3-dihydroxyacetone (DHA) offer green and sustainable alternative routes to fossil-based routes in polymer chemistry. Current methods are based on the metal catalysts. Herein, a metal-free carbon catalyst was discovered to be robust for synthesis of FDCA and GA through the selective oxidation of HMF and DHA, respectively. Experimental data and theoretical calculations indicate defective carbon sites and surface oxygen-containing functional groups play pivotal roles in the excellent catalytic performance. The defective sites activate oxygen molecules, producing reactive oxygen species, while the oxygen-functional groups enhance the adsorption and activation of substrates on the catalyst surface, thereby boosting catalytic efficiency. Additionally, the plausible reaction mechanisms were proposed for the selective oxidation of HMF to FDCA as well as DHA to GA over the carbon catalyst are presented.