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Effects of Copper Exchange Levels on Complexation of Ammonia in Cu (II)-exchanged X Zeolite


CO Kowenje
DC Doetschman
J Schulte
CW Kanyi
J DeCoste
SW Yang
BR Jones

Abstract

Copper (II)-exchanged faujasite-X zeolites at various loadings of copper per unit cell of zeolites were prepared and then exposed to ammonia. The copper ammine complexes of the various copper levels per unit cell were characterized and analyzed by a combination of diffuse reflectance, X-ray powder diffraction, FT-infrared spectroscopy, electron paramagnetic resonance and nuclear magnetic resonance spectroscopic methods. At low copper exchange levels (<5 copper atoms per unit cell), the major complex is [Cu(Ozeo)2(NH3)2]2+ and it is strongly bound to the zeolite framework walls at single four ring sites (site III). Above five copper atoms per unit cell, the major complex becomes [Cu(NH3)4]2+ and it is least interacting with the zeolite framework walls. The [Cu(NH3)4]2+ complex which was formed at higher copper levels per unit cell was most favoured by the presence of maximal amount of ammonia.

Keywords: Cation Exchange, Catalysis, Copper, Complexation, Copper Ammines

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eISSN: 1996-840X
print ISSN: 0379-4350