A TiO2/Nb2O5·nH2O heterojunction catalyst for conversion of glucose into 5-hydroxymethylfurfural in water

A series of water-tolerant Lewis acidic TiO2/Nb2O5·nH2O heterojunction catalysts with different Ti : Nb ratios have been prepared and investigated in the conversion of glucose into HMF in water. Under optimized conditions (i.e. 150 °C, 300 min), 5-hydroxymethylfurfural (HMF) was obtained in 42% yield together with formic acid (FA) in 17% yield. Extending the reaction time, the yield of FA can be increased to over 60%, albeit at the expense of HMF which is reduced to <3% yield. The TiO2/Nb2O5·nH2O catalyst also shows high activity in the conversion of cellobiose and potato starch into HMF. The catalyst is stable and can be reused several times with only a slight decrease in activity.