The development of efficient catalytic systems for the dehydration of carbohydrates to produce 5-hydroxymethylfurfural (HMF) is a very attractive topic. In this work, we synthesized a novel Nb-containing catalyst by the reaction of niobium chloride and nitrilotris(methylenephosphonic acid) (NTMPA), denoted as Nb–NTMPA. The synthesized Nb–NTMPA was characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), N2 adsorption–desorption, and Fourier transform infrared spectroscopy and used as the heterogeneous catalyst for the dehydration of fructose into HMF using the mixture of N,N-dimethylacetamide (DMA) and salts as the reaction solvent. It was found that Nb–NTMPA was very active for the reaction and a HMF yield of 85.6% could be achieved in a DMA–NaBr mixture under the optimal reaction conditions. Further study indicated that the salts could affect the activity of the reaction systems by the formation of DMA·M+ (M = Li, Na and K) macrocations and weakly ion-paired halide ions. Moreover, Nb–NTMPA/DMA–salt systems could also be used in the production of HMF from inulin and sucrose with satisfactory yields.
