Glycerin Reformation in High Temperature and Pressure Water
MISSOURI UNIV OF SCIENCE AND TECHNOLOGY ROLLA
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The noncatalytic reformation of glycerin in supercritical water was studied in a Haynes 282 tubular reactor. In order to determine which parameters were the most influential, a 23 experimental matrix was conducted, with temperatures of 500 and 700 deg C waterglycerin molar ratios of 31 and 131, and residence times of 30 and 90 seconds, all at a pressure of 24 MPa. It was found that temperature had the largest effect on the two gasification parameters deemed most important, gasification percentage and hydrogen yield. Based on this, the effect of temperature was further investigated by looking at 50 deg C intervals from 500 to 800 deg C. From this it was determined that a temperature of 700 to 750 deg C was most conducive to glycerin reformation. The results were compared to equilibrium, as calculated by Gibbs free energy minimization. It was found that at temperatures from 750 deg C to 800 deg C most of the results were at equilibrium. Based on this, kinetic models were developed for experiments not in equilibrium. The first model is a pseudo first order model of the gasification, which compares favorably with other studies. The second kinetic model takes into account the carbon containing gaseous species. Three reactions are used to model the gaseous products Complete gasification of the glycerin into carbon monoxide and hydrogen, water gas shift of the resulting carbon monoxide, and a reaction in which glycerin and hydrogen combine to produce methane. Other reaction pathways were tested, and they either did not fit the data as well, or were thermodynamically impossible. The reactions are also capable of predicting hydrogen production for most conditions.
- Inorganic Chemistry