Direct probe Fourier transform far-infrared study of cations in (NH/sub 4/)Na-Y and (Pt(NH/sub 3/)/sub 4/)Na-Y zeolites and their in situ deamination reactions
The ammonium, NH/sub 4//sup +/, and tetrammineplatinum (II), (Pt(NH/sub 3/)/sub 4/)/sup 2 +/, cation vibrational modes in self-supporting wafers of (NH/sub 4/)Na-Y and (Pt(NH/sub 3/)/sub 4/)Na-Y have been directly probed by in situ Fourier transform far-infrared (FT-far-IR) spectroscopy in the 300-30-cm/sup -1/ range. These ..cap alpha..-cage cations are found to absorb in the far-IR region at room temperature, around 169 and 42 cm/sup -1/, respectively. By subjecting these materials to an in situ vacuum thermal treatment, it is possible to observe (by mid- and far-IR spectroscopy) the dehydration/deamination processes occurring (a) in (NH/sub 4/)Na-Y, which lead ultimately to the acid zeolite NaH-Y, and (b) in (Pt(NH/sub 3/)/sub 4/)Na-Y, which involves an autoreduction step of the Pt/sup 2 +/ ions so formed, resulting in highly dispersed Pt/sub n//sup 0/ clusters immobilized in NaH-Y. Furthermore, the site locations of the residual Na/sup +/ ions generated in this way can be pinpointed by their characteristic far-IR vibrational signatures; moreover, the observation of Si/Al-induced cation vibrational frequency shifts (Si/Al = 1.0, 1.25, 2.50, 3.8) proves to be a valuable method for directly probing metal-support effects. 11 references, 4 figures, 1 table.
- Research Organization:
- Univ. of Toronto, Ontario
- OSTI ID:
- 5133716
- Journal Information:
- J. Phys. Chem.; (United States), Vol. 89:10
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
AMMONIUM COMPOUNDS
INFRARED SPECTRA
PLATINUM COMPOUNDS
SODIUM COMPOUNDS
ZEOLITES
DEAMINATION
DEHYDRATION
STRUCTURAL CHEMICAL ANALYSIS
SURFACE PROPERTIES
CATALYST SUPPORTS
CATIONS
EXPERIMENTAL DATA
FOURIER TRANSFORM SPECTROMETERS
HEAT TREATMENTS
MEDIUM TEMPERATURE
VACUUM SYSTEMS
ALKALI METAL COMPOUNDS
CHARGED PARTICLES
CHEMICAL REACTIONS
DATA
INFORMATION
INORGANIC ION EXCHANGERS
ION EXCHANGE MATERIALS
IONS
MATERIALS
MEASURING INSTRUMENTS
MINERALS
NUMERICAL DATA
SPECTRA
SPECTROMETERS
TRANSITION ELEMENT COMPOUNDS
400201* - Chemical & Physicochemical Properties