Effects of Sulfation Level on the Desulfation Behavior of Presulfated Pt-BaO/Al2O3 Lean NOx Trap Catalysts: A Combined H2 Temperature-Programmed Reaction, in Situ Sulfur K-Edge X-ray Absorption Near-Edge Spectroscopy, X-ray Photoelectron Spectroscopy, and Time-Resolved X-ray Diffraction Study
| Autor: | Charles Hf Peden, Do Heui Kim, Mark H. Engelhard, Ja Hun Kwak, Janos Szanyi, Jonathan C. Hanson, Xianqin Wang |
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| Rok vydání: | 2009 |
| Předmět: |
chemistry.chemical_classification
Sulfide Chemistry Inorganic chemistry Analytical chemistry chemistry.chemical_element Electron spectroscopy Chemical reaction Sulfur XANES Surfaces Coatings and Films Electronic Optical and Magnetic Materials Catalysis General Energy X-ray photoelectron spectroscopy Physical and Theoretical Chemistry Spectroscopy |
| Zdroj: | The Journal of Physical Chemistry C. 113:7336-7341 |
| ISSN: | 1932-7455 1932-7447 |
| DOI: | 10.1021/jp900304h |
| Popis: | Desulfation by hydrogen of presulfated Pt (2 wt %)-BaO(20 wt %)/Al2O3 with various sulfur loading (S/Ba = 0.12, 0.31, and 0.62) were investigated by combining H2 temperature programmed reaction (TPRX), X-ray photoelectron spectroscopy (XPS), in situ sulfur K-edge X-ray absorption near-edge spectroscopy (XANES), and synchrotron time-resolved X-ray diffraction (TR-XRD) techniques. We find that the amount of H2S desorbed during the desulfation in the H2 TPRX experiments is not proportional to the amount of initial sulfur loading. The results of both in situ sulfur K-edge XANES and TR-XRD show that at low sulfur loadings, sulfates were transformed to a BaS phase and remained in the catalyst rather than being removed as H2S. On the other hand, when the deposited sulfur level exceeded a certain threshold (at least S/Ba = 0.31) sulfates were reduced to form H2S, and the relative amount of the residual sulfide species in the catalyst was much less than at low sulfur loading. Unlike samples with high sulfur loadin... |
| Databáze: | OpenAIRE |
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