Facile Synthesis of SrNb2O6 Nanorods for Enhanced Selective Conversion of Fructose to 5-Hydroxymethylfurfural

Catalytic dehydration of fructose to 5-hydroxymethylfurfural (HMF) is a key reaction in biomass valorization and sustainable chemistry. The development of solid acid catalysts with high selectivity for HMF remains challenging due to the formation of undesired by-products, such as levulinic acid and formic acid in the reaction. In this study, SrNb2O6 catalysts with various morphologies were prepared by a facile one-step hydrothermal method, triggering synergetic catalysis for selective transformation of fructose to HMF. Among the Nb-based mixed oxides synthesized under varying conditions, including different pH environments and Nb concentrations, SrNb2O6 nanorods (denoted as SNO-NR, with pH = 13 and Sr/Nb ratio of 1:2) demonstrated the highest catalytic performance. Specifically, it achieved a 74.9% HMF yield and a selectivity of 78.5% in DMSO at 120°C for 1 hour. Comprehensive characterization analyses collectively indicated that an optimal acid capacity and a balanced Brønsted/Lewis acid ratio, which facilitate synergistic effects, are critical for achieving a highly selective conversion of fructose to HMF. Furthermore, it is also noteworthy that this SNO-NR catalyst was recyclable and stable for up to six runs with a minor reduction in its activity, confirming its remarkable robustness.