Degradation kinetics of dihydroxyacetone and glyceraldehyde in subcritical and supercritical water
- Tohoku Univ., Sendai (Japan). Dept. of Chemical Engineering
Biomass continues to be an important candidate as a renewable resource for energy, chemicals, food, and feedstock. In order to understand the products distribution of cellulose hydrolysis in water, hydrolysis of model compounds of cellulose such as glucose, cellobiose, cellotriose, and cellopentaose is being investigated. One of the important pathways of glucose decomposition was the formation of the C-3 carbon compounds, glyceraldehyde and dihydroxyacetone, which appeared to be isomers and also seemed to have related reaction chemistry. The degradation kinetics of dihydroxyacetone and glyceraldehyde were studied at temperature ranges of 573--673 K, pressures of 25--40 MPa, and residence times from 0.06 to 1.7 s. The reactions of glyceraldehyde gave both dihydroxyacetone and pyruvaldehyde, and yields of dihydroxyacetone were always higher than those of pyruvaldehyde. The reactions of dihydroxyacetone gave glyceraldehyde and pyruvaldehyde, while the yields of pyruvaldehyde were always higher than those of dihydroxyacetone. This pathway involves the reversible isomerization between glyceraldehyde and dihydroxyacetone and their subsequent dehydration to pyruvaldehyde. A model was formulated on the basis of this pathway, and the kinetic rate constants involved were calculated using the experimental results. As the conditions change from subcritical to supercritical, the Arrhenius relationship becomes discontinuous near the critical point of water. At a constant temperature of 673 K, the kinetics constants showed a general increase with an increase in pressure.
- Sponsoring Organization:
- Ministry of Education, Science and Culture (Japan); New Energy and Industrial Technology Development Organization, Tokyo (Japan)
- OSTI ID:
- 514619
- Journal Information:
- Industrial and Engineering Chemistry Research, Vol. 36, Issue 6; Other Information: PBD: Jun 1997
- Country of Publication:
- United States
- Language:
- English
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