Hydrogen production from pyrolysis oil using the steam-iron process: a process design study

The overall energy efficiency of the production of pure hydrogen using the pyrolysis oil driven steam-iron process is evaluated for different process conditions. The process consists of a two-step process (reduction with pyrolysis oil, oxidation with steam) from which pure hydrogen can be obtained, without purification steps. An optimum energy efficiency of 53% is achieved when the equilibrium conversion is obtained in the redox cycle at 800A degrees C. When assuming chemical equilibrium, increasing the process temperature results in a low process efficiency due to a large amount of unreacted steam that needs to be condensed to separate the hydrogen product. Using experimental data in the process simulation, a high-energy efficiency is obtained at 920A degrees C (39%) compared with the efficiency at 800A degrees C (29%). This is caused by the low conversion in the reduction at 800A degrees C. Improving the iron oxide material to enhance the reduction with pyrolysis oil at 800A degrees C, is therefore suggested.