Design of sulfonated mesoporous silica catalyst for fructose dehydration guided by difructose anhydride intermediate incorporated reaction network

A reaction network consisting of dimerization, dehydration and isomerization of fructose for the synthesis of 5-hydroxymethylfurfural (HMF) is devised. Difructose anhydride (DFA) isomers were identified as the primary reaction products and reaction intermediates for HMF formation. The effect of functionalization method on the catalytic performance of sulfonated-ordered MCM-41 or disordered mesoporous silica was studied in terms of solid acidity, mesopore size and reaction severity. It was found that during fructose dehydration, while low reaction severity at low reaction temperature and short reaction time is in favor of formation of DFA products, high reaction severity raises HMF selectivity at the expense of DFA selectivity. A new approach guided by the reaction network for catalyst design is proposed by using weak acidic catalyst and high reaction severity to maximize HMF product yield in suppression of by-product formation. As a demonstration example, 550 degrees C calcined sulfonated MCM-41 possessing NH3 TPD non-detectable acidity catalysed 98% fructose conversion at 77% HMF selectivity using 30% fructose solution and 190 degrees C reaction temperature. (C) 2015 Elsevier B.V. All rights reserved.