title: Catalytic dehydration of xylose to furfural: vanadyl pyrophosphate as source of active soluble species.
abstract: The acid-catalysed, aqueous phase dehydration of xylose (a monosaccharide obtainable from hemicelluloses, e.g., xylan) to furfural was investigated using vanadium phosphates (VPO) as catalysts: the precursors, VOPO(4)·2H(2)O, VOHPO(4)·0.5H(2)O and VO(H(2)PO(4))(2), and the materials prepared by calcination of these precursors, that is, γ-VOPO(4), (VO)(2)P(2)O(7) and VO(PO(3))(2), respectively. The VPO precursors were completely soluble in the reaction medium. In contrast, the orthorhombic vanadyl pyrophosphate (VO)(2)P(2)O(7), prepared by calcination of VOHPO(4)·0.5H(2)O at 550°C/2 h, could be recycled by simply separating the solid acid from the reaction mixture by centrifugation, and no drop in catalytic activity and furfural yields was observed in consecutive 4 h-batch runs (ca. 53% furfural yield, at 170°C). However, detailed catalytic/characterisation studies revealed that the vanadyl pyrophosphate acts as a source of active water-soluble species in this reaction. For a concentration of (VO)(2)P(2)O(7) as low as 5 mM, the catalytic reaction of xylose (ca. 0.67 M xylose in water, and toluene as solvent for the in situ extraction of furfural) gave ca. 56% furfural yield, at 170°C/6 h reaction.
authors: Institute of Catalysis and Petrochemsitry (CSIC), C/Marie Curie 2, Campus de Cantoblanco, 28049 Madrid, Spain.
authors: Irantzu
authors: I
authors: Sádaba
authors: Sérgio
authors: S
authors: Lima
authors: Anabela A
authors: AA
authors: Valente
authors: Manuel
authors: M
authors: López Granados
mesh_terms: D002384:Catalysis; D003460:Crystallization; D011756:Diphosphates / Q000737:chemistry*; D005662:Furaldehyde / Q000138:chemical synthesis*; D010710:Phosphates / Q000737:chemistry*; D033362:Powder Diffraction; D017550:Spectroscopy, Fourier Transform Infrared; D014638:Vanadates / Q000737:chemistry*; D014961:X-Ray Diffraction; D014994:Xylose / Q000737:chemistry*
chemical_list: D011756:Diphosphates; D010710:Phosphates; D014638:Vanadates; D014994:Xylose; D005662:Furaldehyde