To better understand a catalytic process, one needs to monitor several parameters simultaneously during the reaction condition. Those parameters include environment (reactants and products), physical attributes (size/shape/electronic structure/atomic structure) of catalysts, and catalytic properties including activity, selectivity and stability of catalysts. Under many circumstances, these parameters change and affect each other in reaction conditions which makes it very difficult to reveal catalytic mechanisms. Such problem can be well addressed if multiple characterization methods could be combined or correlated. We demonstrated the possibility to correlate X-ray absorption and STEM techniques by using a portable reaction cell on Pt/SiO2 catalyst [1]. In the follow-up work, we studied the same reaction but used a different catalyst, Pd/SiO2 to show the importance of multi-modal operando investigations. By correlating operando STEM, XANES and EXAFS, several Pd phases (Pd hydride, metal and carbide) were detected and monitored under different conditions. In the meanwhile, the activity/selectivity/stability of this catalyst was characterized by GC-MS, surface MS and operando IR micro-spectroscopy. By correlating results from multiple techniques, the changes of catalytic properties of Pd/SiO2 catalyst can be explained.

Multi-modal operando investigations of activities and phase transformations of supported Pd nanocatalysts during ethylene hydrogenation reaction

254th National Meeting (2017)

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