Kinetic investigation of sorbitol and xylitol dehydration catalyzed by silicotungstic acid in water

Sorbitol and xylitol dehydration reactions have been investigated regarding their kinetic properties. The reactions were catalyzed by silicotungstic acid in water under hydrogen pressure at temperatures ranging from 160 °C to 200 °C. The products have been measured by HPLC at regular intervals and reaction models have been developed based on these results. Modeling of the experimental data has been done with Presto-Kinetics® and the resulting reaction rates have been used to determine activation energies of all involved reaction steps. By this way, a set of four activation energies was obtained for the dehydration of sorbitol to its products, including 1,4-sorbitan and isosorbide. The activation energy for the dehydration of xylitol to 1,4-anhydroxylitol could also be obtained.

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► Kinetic behavior of sorbitol and xylitol dehydration was investigated.
► Differential equations for modeling sorbitol and xylitol dehydration were proposed.
► Reaction rates at different temperatures could be obtained.
► Activation energies for all reaction steps were successfully calculated.
► Selectivity of sorbitol dehydration could be influenced by temperature.