Quantification of produced hydrogen in a cyclic water gas shift process with Mo stabilized iron oxide

Contaminant free hydrogen can be produced by repeated reduction–oxidation cycles of modified iron oxide material in a fixed bed reactor. Fe2O3–Ce0.5Zr0.5O2 mixed oxide was synthesized by urea hydrolysis, impregnated with Mo (1–5 wt.%), and thermally calcinated in air after the Mo impregnation. The influence of the synthesis method and the Mo addition was investigated by means of X-ray diffraction (XRD), temperature programmed reduction (TPR), scanning electron microscopy (SEM) and BET surface area. In the present study, the material stability was investigated over 200 repeated redox-cycles at 750 °C, and a highly stabilized operation and constant hydrogen generation was observed after about 30 to 40 cycles. The quantification of produced hydrogen attained during the steam oxidation showed a partial utilization of the theoretically maximal H2 capacity of the applied iron oxide material. Approximately 4.2 to 4.7 mmol hydrogen per gram of initially loaded material (Fe2O3–Ce0.5Zr0.5O2) was generated during a steam treatment of the reduced material. The experimentally obtained H2 is 30 to 34% of the maximally achievable amount of hydrogen.