Sulfonated carbons with 20–33 % of weaker acid sites (surface carboxylic acid, alcohol, and phenol groups) present the best turnover number of platform molecule production (TON_Furan ) from fructose and xylose.

Abstract

Sulfonated carbons and commercial Amberlyst 15 and 45 served as model catalysts to explore the impact of the ratio between stronger and weaker acid sites (N_S/N_W ) on 5-hydroxymethylfurfural (HMF) and furfural production from fructose and xylose. Catalysts with varying structural and surface properties, and consequently different N_S/N_W ratios, were prepared from diverse templated mesoporous carbons and distinct sulfonation methods. HMF or furfural yields exhibited an exponential correlation with the N_S/N_W ratio. However, the catalytic activity per site (TON) displayed a volcano-like plot, reaching a maximum between N_S/N_W =2–4. Consequently, our findings suggest the involvement of both strong (sulfonic acid) and weak acid (surface carboxylic acid, alcohol, and phenol groups) sites in monosaccharide dehydration mechanisms. These insights may guide the development of novel catalysts.