Analysis of d-Electron State of Platinum Salts on Silica During Thermal Decomposition by a Laboratory-type X-ray Absorption Spectrometer – Choice of Parameters for in situ Experiments

• Published in: BUNSEKI KAGAKU Vol. 64; no. 12; pp. 889 - 894
• Main Authors: YAMAMOTO, Takashi, MIYAMOTO, Kazunori, KONDO, Masaya, YUKUMOTO, Akira
• Format: Journal Article
• Language: Japanese; English
• Published: Tokyo The Japan Society for Analytical Chemistry 01.12.2015; Japan Science and Technology Agency
• Subjects: Cationic; d-electron occupancy; Heat treatment; In situ measurement; in situ XANES; laboratory-type XAFS spectrometer; Monochromators; Platinum; silica-supported platinum catalyst; Silicon dioxide; Spectrometers; X-rays
• ISSN: 0525-1931
• DOI: 10.2116/bunsekikagaku.64.889

The decomposition behavior of H2PtCl6 or Pt(NH3)4Cl2 supported on amorphous silica was investigated by X-ray absorption near edge spectroscopy using a laboratory-type spectrometer. The choice of a monochromator crystal, the slit width and the acquisition time for in situ measurements of catalyst samples is discussed. The whiteline intensities at the Pt L3 edge XANES did not always reflect on the oxidation state of the platinum species, but on the d-orbital occupancy, as pointed out previously. The changing behavior of the Pt d-orbital occupancy of platinum species on silica upon a thermal treatment in air was evaluated by Pt L2,3 edge XANES with Mansour’s method. Metallic platinum formed on silica after calcination at 773 K under air, but cationic platinum species were suggested to have remained.