Thermodynamic Analysis of Steam Reforming of Glycerol (SRG) for Hydrogen Production at Atmospheric Pressure

Thermodynamic chemical equilibrium analysis of steam reforming of glycerol (SRG) for selective hydrogen production was performed based on the Gibbs free energy minimisation method. The ideal SRG reaction (C3H8O3 + 3 H2O  3 CO2 + 7 H2) and a comprehensive set of side reactions during SRG are considered for the formation of a wide range of products. Specifically, this work focused on the analysis of formation of H2, CO2, CO and CH4 in the gas phase and determination of the carbon free region in SRG under the conditions at atmospheric pressure, 600–1,100 K and 1–10 atm with the steam-to-glycerol feed ratios (SGFR) of 1:5–10. The reaction conditions which favoured SRG for H2 production with minimum coke formation were identifies as: atmospheric pressure, temperatures of 900–1,050 K and SGFR of 10:1. The influence of using the inert carrier gas (i.e. N2,) in SRG was studied as well at atmospheric pressure. Although the presence of N2 in the stream decreased the partial pressure of reactants, it was beneficial to improve the equilibrium yield of H2. Under both conditions of SRG (with/without inert gas), the CH4 production is minimised, and carbon formation was thermodynamically unfavoured at steam rich conditions of SGFR >5:1.