Tuning the Hydrophobicity and Lewis Acidity of UiO-66-NO2 with Decanoic Acid as Modulator to Optimise Conversion of Glucose to 5-Hydroxymethylfurfural

Abstract

Glucose conversion to 5-hydroxymethylfurfural (HMF) is important to the success of a biorefinery. Herein, metal–organic frameworks (MOFs) with the UiO-66 structure were synthesised with decanoic acid as the modulator and used as the catalyst to optimise HMF yield. PXRD, FTIR, and TGA/DSC techniques were applied to characterise the materials. The analysis results show that the materials assembled from the ligand 2-nitroterephthalic acid and hexameric Zr-oxo clusters contain decanoic acid chemically bound in the framework that influences porosity, Lewis acidity, and hydrophobicity. The materials exhibit excellent catalytic performance for HMF production from glucose in DMSO as solvent, attributed to their abundant defects and high hydrophobicity due to the addition of the decanoic acid modulator. Influences of catalyst dosages, reaction duration, and temperature were comprehensively investigated, leading to 98.1% conversion of glucose and 54.5% HMF yield under optimised reaction conditions. The catalytic conversion shows some deterioration after four cycles, yet the reaction selectivity displays no significant decline.