Tuning the Acidity of ZSM‐5 for the Conversion of Fructose Into 5‐Hydroxymethylfurfural in a Biphasic System

Abstract

5‐Hydroxymethylfurfural (HMF) serves as a key platform compound for the synthesis of value‐added chemicals. In this work, a synergistic catalytic system comprising tetrahydrofuran (THF)/saturated NaCl aqueous solution and sulfonic acid‐functionalized ZSM‐5 zeolites was proposed for highly efficient fructose dehydration to HMF. The acidity of the catalyst was tailored by controlling the Si/Al molar ratio of the zeolite and by postsynthetic sulfonation. It was found that decreasing the Si/Al ratio enhances the total acidity and promotes fructose conversion, while the introduced –SO 3 H groups significantly improve HMF selectivity. Under optimized conditions, the functionalized ZSM5‐130 (with a Si/Al molar ratio of 130) catalyst, coupled with the THF/H 2 O–NaCl biphasic solvent, affords an HMF yield of 87% (150°C for 5 h). The system also demonstrates excellent reusability and facile catalyst separation, highlighting its potential for practical biorefinery applications.