EPR and ESEEM study of silver clusters in ZK-4 molecular sieves

• Autorzy: Sadło J. , Michalik J. , Kevan L.
• Konferencja: Proceedings of the 2nd Polish-Japanese Workshop on Materials Science "Materials for Sustainable Development in the 21st Century" 12-15 October 2005, Warsaw, Poland
• Języki publikacji: EN

Abstrakty

EN

Silver clusters generated by g-irradiation in ZK-4 zeolites – isostructural with Linde type A (LTA) zeolite, have been studied by electron paramagnetic resonance (EPR) spectroscopy. It was shown that even a small decrease of cation capacity resulting from a lower Si/Al ratio in the framework affects distinctly silver agglomeration. In dehydrated ZK-4 with Si/Al = 1.2 and 2.4 only silver dimers are stabilized, whereas in Linde 4A silver hexamers were trapped. In ZK-4 exposed to H2O and CH3OH, silver tetramers Ag43+ efficiently are formed. The results of electron spin echo envelope modulation (ESEEM) showed that the adsorbate molecules are in close vicinity to the clusters. It was postulated that in zeolites with low cation capacity the adsorbate molecules make difficult Ag0 migration promoting the reactions with Ag+ cations located in the same sodalite cage.

Słowa kluczowe

EN

ZK-4; EPR; ESEEM; silver clusters

• Wydawca: Institute of Nuclear Chemistry and Technology
• Czasopismo: Nukleonika
• Rocznik: 2006
• Tom: Vol. 51,suppl.1
• Strony: 49--54
• Opis fizyczny: Bibliogr. 15 poz., rys.

Twórcy

autor

Sadło J.

autor

Michalik J.

autor

Kevan L.

• Department of Radiation Chemistry and Technology, Institute of Nuclear Chemistry and Technology, 16 Dorodna Str., 03-195 Warsaw, Poland, Tel.: [phone], Fax: [phone],

Bibliografia

• 1. Dikanov SA, Shubin AA, Parmon VN (1981) Modulation effects in the electron spin echo resulting from hyperfine interaction with a nucleus of an arbitrary spin. J Magn Reson 42:474−487
• 2. Hermerschmidt D, Haul R (1980) ESR studies on the reduction process of silver zeolites. Bunsen-Ges Phys Chem 84:902−907
• 3. Kerr GT (1966) Chemistry of crystalline aluminosilicates.II. The synthesis and properties of zeolite ZK-4. Inorg Chem 5:1537−1539
• 4. Michalik J, Azuma N, Sadło J, Kevan L (1995) Silver agglomeration in SAPO-5 and SAPO-11 molecular sieves.J Phys Chem 99:4679−4686
• 5. Michalik J, Sadło J, Danilczuk M, Perlińska J, Yamada H (2002) Cationic silver clusters in zeolite rho and sodalites. In: Aiello R, Giordano G, Testa F (eds) Impact of zeolites and other porous materials on the new technologies at the beginning of the new millennium.Elsevier. Studies in Surfaces Science and Catalysis,vol. 142, pp 311−318
• 6. Michalik J, Sadło J, van der Pol A, Reijerse E (1997)EPR and ESEEM studies on silver hydroxymethyl radicals in molecular sieves. Acta Chem Scand 51:330−333
• 7. Michalik J, Sadło J, Yu JS, Kevan L (1996) Tetrameric silver clusters in rho zeolite stable above room temperature – ESR studies. Colloids Surf A 115:239−247
• 8. Michalik J, Wąsowicz T, Sadło J, Reijerse EJ, Kevan L (1996) Pulsed EPR for studying silver clusters. Radiat Phys Chem 47:75−81
• 9. Michalik J, Yu JS, Sadło J (2000) ESR studies of silver clusters in the isostructural A and ZK-4 molecular sieves.Bull Pol Acad Sci, Chem 48:293−301
• 10. Michalik J, Zamadics M, Sadło J, Kevan L (1993)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. J Phys Chem 97:10440−10444
• 11. Morton JR, Preston KF (1986) Paramagnetic silver clusters in γ-irradiated Ag-A molecular sieves. J Magn Reson 68:121−128
• 12. Sadło J, Danilczuk M, Michalik J (2001) Interaction of tetrameric silver with ammonia in AgCs-rho zeolite. Phys Chem Chem Phys 3:1717−1720
• 13. van der Pol A, Reijerse EJ, de Boer E, Michalik J (1996)Identification of a silver hydroxymethyl radical in Ag-NaA zeolite using electron spin echo envelope modulation spectroscopy. J Phys Chem 100:3728−3731
• 14. van der Pol A, Reijerse EJ, de Boer E, Wąsowicz T,Michalik J (1992) The EPR spectrum of Ag32+. Mol Phys 75:37−42
• 15. Wąsowicz T, Mikosz J, Sadło J, Michalik J (1992)Organosilver radicals in gamma-irradiated Ag-NaA zeolite with methanol adsorbate. J Chem Soc Perkin Trans 2:1487−1491