Improved Surface Acidity of Niobium Doped Tungstated-Zirconia Solid Acid Catalyst over Production of  5-Hydroxymethylfurfural

The 5-hydroxymethylfurfural (5-HMF) acts as an important chemical intermediate to bridge the biomass resources and industrial applications, which shows the potential for green development. However, the performance of biomass materials conversion to 5-HMF is still limited in the green solvent. Herein, an effective approach is reported to prepare the highly efficient solid acid catalysts, NbO_x /WO_y -ZrO₂, to improve fructose conversion. It is found that the introduction of Nb results in the generation of the niobium oxides, which improves acid sites and tunes the ratios of Brønsted acid and Lewis acid on the surface of the WO_y -ZrO₂ support. With the acidity improvement and increasing acid sites of the NbO_x /WO_y -ZrO₂, the highest fructose conversion is 99%  in water. Meanwhile, the 5-HMF yield and the selectivity are also as high as 50.1% and 50.7% under the reaction temperature of 180 °C for a short reaction time of 30 min. The proposed NbO_x /WO_y -ZrO₂ catalyst strategy will not only open a new way for designing the solid acid catalysts to achieve high performance of the 5-HMF in the water, but also promote the green production of biomass and sustainable development in the future.