Thermodynamic analysis of aqueous-reforming of polylols for hydrogen generation

This paper aims to study the thermodynamic features of polylols reforming to generate hydrogen gas. Polylols can be converted into carbon dioxide and hydrogen via aqueous reforming with co-existence of low level of carbon monoxide due to reverse water-gas-shift (R-WGS) reaction and subsequently, CO and/or CO2 and H2 react to form CH4 via side reaction of methanation. Here Matlab language is employed to calculate the reaction heat, equilibrium constant and equilibrium molar fraction of each component through solving the non-linear equations. The calculation results suggest that the polylol reforming reaction is endothermic and but should be carried at low temperature to give very low level of CO content (dry basis) in the gas production. The results also demonstrate that low temperature favors the methanation, which should be limited kinetically during the operation. In addition, choosing system pressure slightly higher than the saturation water pressure is unfavorable to the R-WGS reaction but favorable to the low level of CO content, desirably.