The use of heterogeneous catalysts for conversion of sugars and sugar alcohols to value-added chemicals has been widely studied in liquid phases.Low selectivities and high costs associated with catalyst recovery have substantially limited commercialization of these processes.Gas phase packed-bed catalysis has recently been successful in overcoming these obstacles for the hydrogenolysis of glycerol to propylene glycol.In this paper,the evaporation of glucose and sorbitol was investigated to identify potential conditions for gas-phase conversions of these sugars.In our studies,vapor pressures of sorbitol were estimated in a wider temperature range of(250 to 350)°C than work done by Guido et al.(J.Chem.Soc.Faraday Trans.1990,86,75-79)at(177 to 227)°C.A thermogravimetric analysis(TGA)method was used to estimate a boiling point of 362°C for sorbitol with sorbitol's vapor pressure following a Clausius-Clapeyron model behavior.In addition,evaporation studies demonstrated sobitol evaporation and condensation on a practical level.The evaporation of sorbitol was experimentally validated with no decomposition at 0.1 bar and 294°C and 2.5%(mass fraction)in water.The evaporation of high-concentration sorbitol feed can be achieved by mixing with a high-temperature gas(e.g.,steam).Glucose evaporated with partial decomposition at temperatures as low as 220°C.
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