Niobium phosphates as bifunctional catalysts for the conversion of biomass-derived monosaccharides

The direct conversion of glucose and xylose into HMF and furfural is more efficient using a combination of Lewis and Br?nsted acids. Herein, niobium phosphates were prepared with different compositions, which affect its surface acidity and, consequently, the catalytic activity. The catalysts with a high P/Nb molar ratio presented a low molar ratio between Lewis and Br?nsted acid sites (L/B ratio), while those with low P/Nb molar ratio displayed a high L/B ratio. NbP-2, the sample with the highest L/B ratio, showed the highest reaction rate for both HMF and furfural formation. It was found, indeed, that the reaction rate for monosaccharides conversion and furans formation correlate linearly with the L/B ratio. The results presented not only introduce niobium phosphates with a high L/B molar ratio as promising catalysts for HMF and furfural production but also provide fundamental knowledge that will guide the design of other bifunctional heterogeneous catalysts.

Automated summary

The study found that the surface acidity of niobium phosphates and the ratio of Lewis to Br?nsted acid sites (L/B ratio) affect their catalytic activity in converting glucose and xylose into HMF and furfural. Catalysts with high L/B ratio showed higher reaction rates, providing greater efficiency for the formation of HMF and furfural.