Synergy of Wettability and Acidity in Carbon-Based Acid Catalysts for Efficient Conversion of Glucose to 5-Hydroxymethylfurfural

Abstract

The efficient conversion of glucose to 5-hydroxymethylfurfural (HMF), a key biobased platform chemical, is critical for sustainable biorefineries. However, achieving high HMF selectivity remains challenging due to the side reactions and intricate interplay between catalyst acidity and the reaction microenvironment. This study addresses this challenge by developing a bifunctional carbon-based solid acid catalyst from bio-tar waste, strategically engineered to optimize both acid site configuration and surface wettability. Lewis acid sites were introduced via Al-Ti bimetallic nanoparticles and Brønsted acidity was precisely tuned by grafting sulfonic acid groups achieving the best balance. By modifying the hydrophobicity of the carbon carrier, a moderate water contact angle of 24-27° is found to be essential for high performance, which ensures efficient mass transfer of the hydrophilic glucose substrate to the active sites while effectively repelling water molecules from the vicinity of the formed HMF, thereby suppressing its rehydration. In a biphasic NaCl-H 2 O/DMSO system at 140 °C for 4 hours, it achieved complete glucose conversion with a remarkable HMF yield of 83.6% and selectivity of 83.1%. The findings highlight the synergy cooperation between tailored surface wettability and balanced acid functionality and provides a novel design strategy for optimizing heterogeneous catalyst for efficient biomass conversion.