Weak-acid biochar catalyst prepared from mechanochemically-activated biomass and humic acid for production of 5-hydroxymethylfurfural

Article highlights Carbonization (1 h, 400 °C, N2) of mix ball-milled (10 min) waste leaves and humic acid affords weak-acid biochars. As-prepared weak-acid biochars (–COOH, OH, amino groups) were activated solids with adsorptive and catalytic properties. Weak-acid biochar catalyst is reusable and promotes fructose dehydration to 5-HMF in yields of 77.5% (140 °C, 60 min).