Efficient conversion of cellulose into 5-hydroxymethylfurfural over niobia/carbon composites.

A series of novel niobia/carbon composites were synthesized by hydrothermal method following by carbonization with niobium tartrate and glucose as precursors, and used in the conversion of glucose and cellulose to 5-hydroxymethylfurfural (HMF). These catalysts were characterized by XRD, SEM, TEM, N 2 adsorption/desorption, NH 3 -TPD and Py-FTIR techniques and the results showed that the Nb/C catalysts were agglomerated particles, with weak to medium acid strength and suitable Brønsted/Lewis acid sites. When used in the hydrolysis and dehydration of cellulose, as high as 53.3% yield of HMF was achieved over Nb/C-50 catalyst at 170 °C for 8 h, accompanied with 24.5% glucose, with the total conversion of cellulose, indicating the high carbon yield and excellent activity. Furthermore, this catalyst showed excellent recyclability and its catalytic activity still maintained after 8 cycles. [ABSTRACT FROM AUTHOR]