Synthesis Gas Production by Noncatalytic Reforming of Glycerin in Supercritical Water: Effect of Reaction Temperature

Due to an increased demand for biodiesel, there has been an increased production of crude glycerin, a byproduct of biodiesel production via transesterification reaction, thus creating a surplus situation for glycerin on the world chemical market. Crude glycerin contains up to 20% water by weight, which must be removed and the glycerin purified to be used for most applications. The noncatalytic reformation of glycerin in supercritical water is a promising solution to the process intensive removal of the water content of crude glycerin and an effective use of glycerin as an alternative energy source, in particular synthesis gas and hydrogen. Experiments were conducted using a tubular 0.4-L Haynes® Alloy 230 supercritical water reactor over a temperature rage of 500 to 700 °C, with concentrations of 27.5 weight percent glycerin in aqueous solutions, reactor space times of 100 and 150 seconds, and a pressure of 24.20 ± 0.03 MPa. Complete gasification of glycerin was achieved, with the hydrogen yield reaching a maximum around 600°C.