A comparative thermodynamic and experimental analysis on hydrogen production by steam reforming of glycerin

Glycerin production has soared with the increase in biodiesel production in recent years. One possibility of using this excess glycerin is in hydrogen production. Steam reforming of glycerin for hydrogen production involves complex reactions. As a result, several intermediate byproducts are formed and end up in the product stream, affecting the final purity of the hydrogen produced. Furthermore, the yield of the hydrogen depends upon several process variables, such as the temperature, ratio of reactants, and system pressure. In this study, a thermodynamic equilibrium analysis coupled with experimentation has been performed for the steam-reforming process of glycerin over the following variable ranges: pressure of 1-5 atm, temperature of 600-1000 K, and water/glycerin feed ratio of 1:1-9:1. The equilibrium concentrations of different compounds were calculated by the method of direct minimization of the Gibbs free energy. The study revealed that the best conditions for producing hydrogen are as follows: temperature of > 900 K, atmospheric pressure, and a molar ratio of water/glycerin at 9:1. Under aforementioned conditions, methane production is minimized and the carbon formation is thermodynamically inhibited. Experimental results over the Ni/MgO catalyst were compared against the results obtained from thermodynamic analysis.