Direct conversion of glucose to 5-hydroxymethylfurfural using a mixture of niobic acid and niobium phosphate as a solid acid catalyst

• Published in: Fuel (Guildford) 2017-12, Vol.210, p.67-74
• Main Authors: Catrinck, Mariana N., Ribeiro, Emerson S., Monteiro, Robson S., Ribas, Rogério M., Barbosa, Márcio H.P., Teófilo, Reinaldo F.
• Format: Article
• Language: English
• Subjects: Acidity; Acids; Catalysis; Catalysts; CCD design; Dehydration; Design; Design optimization; Direct conversion; Glucose; Heterogeneous catalysis; Hydroxymethylfurfural; Lignocellulosic biomass; Niobium; Niobium oxides; Optimization; Optimization process; Phosphates; Selectivity; Studies; Substrates; Sugarcane; Temperature
• ISSN: 0016-2361; 1873-7153
• DOI: 10.1016/j.fuel.2017.08.035

[Display omitted] •HMF was produced by solid acid-catalyzed glucose in an aqueous medium.•Nb2O5·nH2O, NbOPO4·nH2O and a mixture of both was used as a solid acid catalyst.•CCD was used for process optimization for maximizing the glucose conversion to HMF.•Highest HMF selectivity was 56%, obtained for a mixture of NbO and NbP.•The mixture of NbO and NbP is an effective catalyst for glucose dehydration to HMF. The aim of this work was to optimize the acid-catalyzed conversion of glucose into 5-hydroxymethylfurfural (HMF) in an aqueous medium using niobic acid (NbO), niobium phosphate (NbP) and a mixture of both solid acid catalysts. A simplex-centroid mixture design was applied to optimize the mixture ratio between NbO and NbP. A central composite design was applied to process optimization. The studied variables were temperature (T), time (t) and substrate to catalyst weight ratio (RS/C). The mixture design revealed excellent glucose conversion (55%) and HMF selectivity (56%) when the weight ratio between NbO and NbP was equal to 1:1. The experimental results demonstrate that a mixture of both solid acids provides a better combination of Brønsted and Lewis acidity for effective glucose dehydration into HMF than each individual catalyst.