Hydrogen production by autothermal system : catalyst studies

Abstract

Autothermal system is an alternative system for producing hydrogen using a combination of partial oxidation and steam reforming in a single reactor. For efficient energy utilization, heat generated from partial oxidation will be provided for the steam reforming reaction whereas coke formation can be eliminated in the presence of O2. In a previous study, Ni/Ce0.75Zr0.25O2 catalyst was found to be a promising candidate for both partial oxidation and steam reforming, thus it would be beneficial for use in the autothermal system. To further investigate the significance of Ni loading, the amount of Ni added over Ce0.75Zr0.25O2 catalyst was varied from 5 to 15 wt%. The catalysts were prepared by two conventional methods, i.e. impregnation and sol-gel methods. It was found that the 1 5%Ni/Ce0.75Zr0.25O2 catalyst exhibited the highest catalytic activity regardless of the method of preparation. Autothermal system studies of the effects of H2O/C and O2/C ratios on 15%Ni/ Ce0.75Zr0.25O2 showed that the H2/CO ratio increased with increasing H2O/C and O2/C ratios.