Electron spin resonance and electron spin echo modulation studies on radiation-induced silver agglomeration in a SAPO-42 molecular sieve: A comparison with isostructural zeolite A

Journal Article · Thu Oct 07 04:00:00 EDT 1993 · Journal of Physical Chemistry; (United States)

DOI:https://doi.org/10.1021/j100142a029· OSTI ID:5525848

Michalik, J; Sadlo, J ^[1]; Kevan, L; Zamadics, M ^[2]

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1. Inst. of Nuclear Chemistry and Technology, Warsaw (Poland)
2. Univ. of Houston, TX (United States)

This study focuses on paramagnetic silver species produced by [gamma]-radiolysis of a silver silicoaluminophosphate-42 (Ag-SAPO-42) molecular sieve. Electron spin resonance and electron spin echo modulation spectroscopies have been used to study the structure, location, and coordination of silver adducts and clusters stabilized in dehydrated SAPO-42 and exposed to methanol and ammonia. It was found that in dehydrated AG-SAPO-42, small silver clusters are formed with very low yield, whereas, in AgNa-A, Ag[sub 3][sup 2+] or AG[sub 6][sup b+] clusters are efficiently stabilized. The less restricted mobility of Ag[sup 0] in SAPO-42 due to its lower cation capacity is postulated to explain the observed differences. In the presence of methanol and ammonia in the molecular sieve cages, the differences are less significant. The major paramagnetic products of radiolysis in both SAPO-42 and type A molecular sieves are silver methoxy radicals (methanol adsorbed) or silver-ammonia adducts (ammonia adsorbed). They are located in [alpha]-cages, although the electron spin echo modulation results suggest some differences in location, possibly due to a different distribution of negative charge between the aluminophosphate and aluminosilicate frameworks. 22 refs., 7 figs., 1 tab.

• OSTI ID: 5525848
• Journal Information: Journal of Physical Chemistry; (United States), Journal Name: Journal of Physical Chemistry; (United States) Vol. 97:40; ISSN JPCHAX; ISSN 0022-3654
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
400500 -- Photochemistry
ADSORBENTS
AGGLOMERATION
CATALYSTS
CHEMICAL RADIATION EFFECTS
CHEMICAL REACTIONS
DECOMPOSITION
ELECTRON SPIN RESONANCE
ELEMENTS
HYDROGEN COMPOUNDS
INORGANIC ION EXCHANGERS
ION EXCHANGE
ION EXCHANGE MATERIALS
MAGNETIC RESONANCE
MATERIALS
METALS
MINERALS
MOLECULAR SIEVES
OXYGEN COMPOUNDS
PHOTOCHEMICAL REACTIONS
PHOTOLYSIS
RADIATION EFFECTS
RADIOLYSIS
RESONANCE
SILICATE MINERALS
SILVER
SILVER COMPOUNDS
SPIN ECHO
TRANSITION ELEMENT COMPOUNDS
TRANSITION ELEMENTS
WATER
ZEOLITES