Hydrogen production from steam–methanol reforming: thermodynamic analysis

Thermodynamic equilibrium involved in the steam reforming of methanol is re-examined to cover the extended range of compounds suggested by literature to be involved in the reactions. The equilibrium concentrations are determined for different mixtures of these compounds at 1 atm and at different temperatures (360–573 K) and at different steam/methanol molar feed ratios (0–1.5), by the method of direct minimization of Gibbs free energy. The possibility of carbon formation in these conditions is determined by direct inclusion of carbon in the objective function of the minimization scheme. Results showed that the area of carbon formation region is surprisingly high. Carbon and methane formations are thermodynamically favoured and they reduce the quantity and quality of hydrogen produced. Dimethyl ether formation occurs at low temperatures and low steam/carbon feed ratios, while carbon monoxide occurs at high temperatures and low steam carbon ratios.