Stabilization of metal ensembles at room temperature: Palladium clusters in zeolites
- Univ. of New Mexico, Albuquerque (USA)
- Eindhoven Univ. of Technology (Netherlands)
Palladium clusters of low nuclearity have been prepared in the cavities of X zeolites via ion exchange with Pd(NH{sub 3}){sub 4}Cl{sub 2}, oxidative dehydration, and subsequent reduction of the dry Pd(II) zeolites with hydrogen at 295 and 425 K. Detailed EXAFS analysis of Pd K-edge data shows that the average first-shell Pd-Pd coordination number of the reduced system is only about N = 1.5 at a distance of 2.78 {angstrom}. A long, relatively disordered coordination of the reduced Pd to framework oxygen and silicon indicates the stabilizing, templating function of the zeolite matrix. Geometric models based upon the EXAFS results show that intrazeolite Pd{sub 2}, Pd{sub 3}, and Pd{sub 4} clusters are formed by partial occupation of SI{prime} and SII{prime} positions of the sodalites subunits of the zeolite. This study presents evidence for the formation of molecular metal ensembles stabilized in as open-framework matrix to at least 425 K.
- DOE Contract Number:
- AS05-80ER10742
- OSTI ID:
- 6972566
- Journal Information:
- Journal of Physical Chemistry; (USA), Journal Name: Journal of Physical Chemistry; (USA) Vol. 93:16; ISSN JPCHA; ISSN 0022-3654
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
360603* -- Materials-- Properties
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201 -- Chemical & Physicochemical Properties
DATA
DATA ANALYSIS
ELEMENTS
EXPERIMENTAL DATA
INFORMATION
INORGANIC ION EXCHANGERS
ION EXCHANGE MATERIALS
MATERIALS
MEASURING INSTRUMENTS
MEASURING METHODS
MEDIUM TEMPERATURE
METALS
MINERALS
NUMERICAL DATA
PALLADIUM
PLATINUM METALS
SOLID CLUSTERS
TRANSITION ELEMENTS
ZEOLITES