Iso-Potential Operando Coupling of XRD and a Profile Reactor: Structural Insights into ZnPd/ZnO during Methanol Steam Reforming.

The dynamic structural changes of ZnPd/ZnO make it the leading contender to improve CO2 selectivity in methanol steam reforming (MSR). The dynamics are reaction-induced and depend upon local chemical potentials, thus making spatially resolved operando investigations imperative. New iso-potential operando (IPO) techniques enable the study of catalysts under identical chemical potentials in separated but coupled cells. Here, the adaptive phase composition and structural changes of ZnPd/ZnO are investigated using iso-potential operando XRD (IPO-XRD) achieved by coupling a profile reactor and operando XRD. The results demonstrate the successful coupling and reveal the spatial variation of additional reflections assigned to ZnCO3, a phase that has not been previously reported. This highlights the potential of IPO-XRD and lays the groundwork for future investigations of other complex and structurally dynamic catalytic systems.