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.
Singhania, A., Krishnan, V., Bhaskarwar, A. N., Bhargava, B., Parvatalu, D., & Banerjee, S. (2017). Hydrogen production from the decomposition of hydrogen iodide over nanosized nickel-oxide-zirconia catalysts prepared by solution-combustion techniques. Catalysis Communications, 93, 5-9. https://doi.org/10.1016/j.catcom.2017.01.020