Thermodynamic study on hydrogen generation from different glycerol reforming processes

This work is to study the thermodynamic property of a glycerol aqueous reforming process to generate hydrogen for fuel cells. Three ways of processing glycerol have been considered: autothermal reforming, a combination of water aqueous reforming and oxidation; aqueous hydrogen peroxide reforming; and the water aqueous reforming process. Thermodynamic analysis on three of them has been carried out, and the results show that the side reaction of methanation in each process route leads to a dramatic decrease of hydrogen content in the gas product, which consequently should be limited kinetically. Comparison among them indicates that, in the absence of methanation, the hydrogen content produced from water aqueous reforming of glycerol is the highest, followed by that from autothermal reforming and that from aqueous hydrogen peroxide reforming. It has also been shown that the requirements of external energy input to sustain these reforming reactions appear inversely among them. Therefore, it can be concluded thermodynamically that the external energy can be reduced at the price of losing hydrogen yield due to the exothermic oxidation, which consumes hydrogen to release energy.