title: Dehydration of Glucose to 5-Hydroxymethylfurfural Using Nb-doped Tungstite.
abstract: Dehydration of glucose to 5-hydroxymethylfurfural (HMF) remains a significant problem in the context of the valorization of lignocellulosic biomass. Hydrolysis of WCl6 and NbCl5 leads to precipitation of Nb-containing tungstite (WO3 ⋅H2 O) at low Nb content and mixtures of tungstite and niobic acid at higher Nb content. Tungstite is a promising catalyst for the dehydration of glucose to HMF. Compared with Nb2 O5 , fewer by-products are formed because of the low Brønsted acidity of the (mixed) oxides. In water, an optimum yield of HMF was obtained for Nb-W oxides with low Nb content owing to balanced Lewis and Brønsted acidity. In THF/water, the strong Lewis acidity and weak Brønsted acidity caused the reaction to proceed through isomerization to fructose and dehydration of fructose to a partially dehydrated intermediate, which was identified by LC-ESI-MS. The addition of HCl to the reaction mixture resulted in rapid dehydration of this intermediate to HMF. The HMF yield obtained in this way was approximately 56 % for all tungstite catalysts. Density functional theory calculations show that the Lewis acid centers on the tungstite surface can isomerize glucose into fructose. Substitution of W by Nb lowers the overall activation barrier for glucose isomerization by stabilizing the deprotonated glucose adsorbate.
authors: Inorganic Materials Chemistry, Eindhoven University of Technology, P.O. Box 513, 5600 MB, Eindhoven, The Netherlands.|King Abdullah University of Science and Technology, KAUST Catalysis Center, Physical Sciences and Engineering Division, 4700 KAUST, Thuwal, 23955-6900, Saudi Arabia.
authors: Chaochao
authors: C
authors: Yue
authors: Inorganic Materials Chemistry, Eindhoven University of Technology, P.O. Box 513, 5600 MB, Eindhoven, The Netherlands.
authors: Guanna
authors: G
authors: Li
authors: Inorganic Materials Chemistry, Eindhoven University of Technology, P.O. Box 513, 5600 MB, Eindhoven, The Netherlands.
authors: Evgeny A
authors: EA
authors: Pidko
authors: Inorganic Materials Chemistry, Eindhoven University of Technology, P.O. Box 513, 5600 MB, Eindhoven, The Netherlands.
authors: Jan J
authors: JJ
authors: Wiesfeld
authors: Shell Global Solutions International B.V., P.O. Box 38000, 1030 BN, Amsterdam, The Netherlands.
authors: Marcello
authors: M
authors: Rigutto
authors: Inorganic Materials Chemistry, Eindhoven University of Technology, P.O. Box 513, 5600 MB, Eindhoven, The Netherlands. e.j.m.hensen@tue.nl.
authors: Emiel J M
authors: EJ
authors: Hensen
mesh_terms: D005662:Furaldehyde / Q000031:analogs & derivatives* / Q000737:chemistry; D005947:Glucose / Q000737:chemistry*; D009556:Niobium / Q000737:chemistry*; D010087:Oxides / Q000737:chemistry*; D011789:Quantum Theory; D012997:Solvents / Q000737:chemistry; D014414:Tungsten / Q000737:chemistry*; D014867:Water / Q000737:chemistry*
chemical_list: D010087:Oxides; D012997:Solvents; D009556:Niobium; D014867:Water; C008046:5-hydroxymethylfurfural; C511604:tungsten oxide; D005662:Furaldehyde; D005947:Glucose; D014414:Tungsten
keywords: 5-hydroxylmethylfurfural; dehydration; glucose; niobium oxide; tungsten oxide