Structural response of Ni/ZrO2 to feed modulations during CH4 reforming reactions

Time resolved oxidation and reduction cycles of ZrO2-supported Ni catalysts for dry reforming of CH4 (CO2 + CH4 <-> 2 CO + 2 H-2) during feed modulations have been studied. Under reaction conditions (1073 K) Ni remains fully reduced, whereas switching the feed gas to pure CO2 results in a slow (25 sec) formation of a stable NiO phase. When switching back to reaction conditions the NiO phase is rapidly reduced (similar to 1 sec) to metallic Ni. In the context of this study, a novel capillary cell has been built, allowing the parallel treatment of 5 catalyst samples with different gas compositions and different pressures. A comparison of the capillary cell to conventional systems regarding the spectral quality and the kinetic data shows that the capillary cell can be used to obtain identical kinetic data and high quality X-ray absorption spectra.