Date: Wednesday, October 12th 2016 

Time: 11:00 AM 

Location: Building 4, Room 125

King Fahd University of Petroleum and Minerals (KFUPM), Dhahran, KSA

 

Many efforts have been made in order to characterize catalyst under relevant working conditions. Recent studies have demonstrated that catalyst surface evolves dynamically under reaction conditions. In order to complement in-situ spectroscopic tools, such as near-ambient X-ray photoelectron spectroscopy (NAP-XPS), with visual information about the active surface structure, we have implemented in-situ scanning electron microscopy (SEM) for the observation of dynamic processes at the µm to nm scale. By coupling in-situ SEM with mass spectroscopy technique we are able to relate structural dynamics of metal catalysts to changes in the gas phase composition. Under specific conditions, oscillatory behavior of the catalyzed chemical reactions was observed for the case of polycrystalline nickel catalyst. These self-sustained oscillations can be utilized to assist the identification of kinetic mechanisms and provide insight into the active and inactive state of the catalyst. The dynamic behavior of the nickel catalyst during hydrogen and ethylene oxidation reactions will be presented. The active state in the oscillatory reaction is dominated by the presence of metallic nickel, while the formation of nickel oxides coincides with the decrease in the catalytic activity. Overall, this talk will outline how the implementation of complementary in-situ SEM and mass spectroscopy techniques can enrich our understanding of the dynamic behavior of active catalysts.