Spectroscopic Study of Surface Dynamics of Al2O3 Supported Pt-Catalysts
Understanding the dynamic changes of heterogeneous catalyst under reaction conditions is very important for improving the catalyst and designing a new catalyst.In present study,a series of A12O3 supported Pt/Al2O3 catalysts were prepared with various Pt loadings.Surface structures and changes were studied by the X-ray diffraction(XRD),X-ray photoemission spectroscopy(XPS),high-angle annular dark field scanning transmission electron microscopy(HAADF-STEM),CO probed Fourier transform infrared spectroscopy(CO-FTIR),low energy ion scattering spectroscopy(LEIS),temperature programmed oxidation of carbon(TPOC)and Raman spectroscopy.Propane dehydrogenation(PDH)was used as a probe reaction.Surface dynamics,especially coke formation,surface morphology and active sites were investigated,and correlated with catalytic performance.It was found that Pt/Al2O3 catalysts underwent an'induction'period for PDH.Propane was easy to deeply dehydrogenate,broke C-C bond on Pt nanoparticles(NP)and clusters to form CH4 and coke,resulted in a lower activity.In contrast,the isolated Pt single-atom central sites(SAC)were not easy to form coke,and would mainly be the active sites for propylene formation.
surface dynamicsin-situ characterizationpropane dehydrogenationPt-based catalystsingle-atom site catalyst
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