Hydrogen production by glycerol steam reforming with in situ hydrogen separation: A thermodynamic investigation

Thermodynamic features of hydrogen production by glycerol steam reforming with in situ hydrogen extraction have been studied with the method of Gibbs free energy minimization. The effects of pressure (1-5 atm), temperature (600-1000 K), water to glycerol ratio (WGR, 3-12) and fraction of H-2 removal (f, 0-1) on the reforming reactions and carbon formation were investigated. The results suggest separation of hydrogen in situ can substantially enhance hydrogen production from glycerol steam reforming, as 7 mol (stoichiometric value) of hydrogen can be obtained even at 600 K due to the hydrogen extraction. It is demonstrated that atmospheric pressure and a WGR of 9 are suitable for hydrogen production and the optimum temperature for glycerol steam reforming with in situ hydrogen removal is between 825 and 875 K, 100 K lower than that achieved typically without hydrogen separation. Furthermore, the detrimental influence of increasing pressure in terms of hydrogen production becomes marginal above 800 K with a high fraction of H-2 removal (i.e., f = 0.99). High temperature and WGR are favorable to inhibit carbon production. (C) 2010 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.