Reaction kinetics of d-xylose in sub- and supercritical water

Taku Michael Aida, Naohiro Shiraishi, Masaki Kubo, Masaru Watanabe, Richard L. Smith

Research output: Contribution to journalArticlepeer-review

103 Citations (Scopus)

Abstract

Reactions of d-xylose were investigated with a flow apparatus in water at high temperatures (350 and 400 °C) and high pressures (40-100 MPa) to elucidate the reaction pathway and reaction kinetics. The products obtained from the reaction of d-xylose were furfural, d-xylulose, glyceraldehyde, glycolaldehyde, dihydroxyacetone, pyruvaldehyde, lactic acid and formaldehyde. Experimental results showed evidence of a dehydration reaction pathway, a retro-aldol reaction pathway and a Lobry de Bruyn-Alberta van Ekenstein (LBET) pathway from d-xylulose. The proposed reaction pathway and kinetic model were in accord with the experimental results. The kinetic constants showed dependence with water density (pressure). At 400 °C and water density of 0.52 g/cm 3 at 40 MPa, the reaction from d-xylose to d-xylulose occurred by the LBET pathway with the reverse reaction being negligible. At 400 °C, increasing the water density from 0.52 to 0.69 g/cm3 decreased the kinetic rate constant of the forward LBET pathway and increased that of the reverse LBET pathway. The kinetic rate constant of the dehydration of d-xylulose to furfural increased with increasing water density at constant temperature. The kinetic rate constant of the retro-aldol reaction of d-xylose increased, and the retro-aldol reaction of d-xylulose decreased with increasing water density at 400 °C.

Original languageEnglish
Pages (from-to)208-216
Number of pages9
JournalJournal of Supercritical Fluids
Volume55
Issue number1
DOIs
Publication statusPublished - 2010 Nov

Keywords

  • Furfural
  • Reaction kinetics
  • Supercritical water
  • d-Xylose

ASJC Scopus subject areas

  • Chemical Engineering(all)
  • Condensed Matter Physics
  • Physical and Theoretical Chemistry

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