ISSN:
1572-879X
Keywords:
HREM
;
small Pt clusters
;
zeolites
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
Notes:
Abstract High resolution electron microscopy (HREM) has been used to study dispersed Pt clusters in NaY- and USY-zeolites. All the samples contained 0.8% Pt and were reduced at temperatures of 300 ° C, 500 ° C and 650 ° C. The size of the Pt clusters ranged from a few å up to ∼ 30 å. When the incident electron beam was sufficiently strong, it caused some of the extremely small metal clusters to sinter. This was usually accompanied by zeolite damage. This in-situ sintering must be taken into consideration when interpreting the particle size distribution results obtained solely by TEM, especially for particles that are smaller than 10 å. The minimum phase contrast imaging condition is demonstrated to be more appropriate than optimum defocus for detecting the extremely small Pt clusters inside the zeolite structures.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00772087
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