Effects of Varying Water-to-Glycerin Molar Ratio for Supercritical Water Reformation of Glycerin

The production of biodiesel has increased in recent years in response to rising demands for renewable alternative energy and the use of green-fuel technologies. A common byproduct generated in the industrial manufacture of biodiesel is glycerin. While glycerin has beneficial properties for a variety of end uses, its over-abundance on the market place has rendered a new challenge for finding other economically viable and sizable end-uses for glycerin. This paper addresses a novel use of glycerin as a starting material for hydrogen generation via non-catalytic reformation using supercritical water. Additionally, effects on the water-gas shift reaction are considered. An experimental feasibility study of the novel conversion process was conducted on a 0.4 L tubular reactor constructed of HaynesŪ Alloy 230. The examined variables for the novel reaction process involved a water-to-glycerin molar ratio ranging from 3:1 to 24:1, a reactor temperature between 868 to 973 K, and space time ranging from 98 to 157 seconds. The effects of the reaction variables, in particular the water-to-glycerin molar feed ratio, on the gaseous hydrogen production, as well as on the overall process chemistry, were mechanistically and kinetically elucidated.