(91d) The Reaction Pathways of Glycerin in Supercritical Water

Glycerin, a byproduct of biodiesel production, is a cheap and widely available feedstock that may be used for hydrogen production in energy application. One method that can be used to produce hydrogen from glycerin is using supercritical water as a reaction medium. The process is non-catalytic and can handle a wide range of impurities. The primary gaseous products of glycerin in supercritical water are hydrogen, carbon monoxide, methane, carbon dioxide, and ethane. In order to optimize this process, a thorough understanding of the reaction pathways of glycerin in supercritical water is needed. The different mechanistic pathways of glycerin in supercritical water were examined, including decomposition, recombination, pyrolysis, and reformation. Reactions occurring between product gases, such as the water gas shift reaction and methanation, were also examined. An experimental study was also performed in order to evaluate the accuracy of the different reaction pathways of glycerin using a 0.1L Haynes® Alloy 282 reactor system, and particular attention was given to the role of supercritical water in the reaction chemistry. Experiments were done at a variety of temperatures, space times, and water-to-glycerin molar ratios to gain a comprehensive understanding of the reaction pathways of glycerin.