Hydrogen production from the decomposition of hydrogen iodide over nanosized nickel-oxide-zirconia catalysts prepared by solution-combustion techniques

NiO/ZrO2 prepared by solution-combustion method (SCM) showed near equilibrium conversions of hydrogen iodide to hydrogen and iodine at 500 °C–550 °C without any performance degradation over 50 h. XRD data of the catalyst after 10 h of reaction were compared with the same after a TPR step in H2/Ar on another catalyst sample, to verify Ni-ex-solution. Ni is clearly visible in the XRD after TPR, although it was not observed under reaction conditions (HI/H2O/N2), even after 10 h. Instead, the onset of monoclinic ZrO2 is observed after reaction, which was not visible after TPR.