Characterization of Cu+ ions in CuHZSM-5 zeolites and CuSAPO-34 molecular sieve Cu+ laser-induced luminescence and Xe-129-NMR diagnosis

We report on an attempt to characterize by laser-induced phosphorescence sp ectroscopy Cu+ sites at low concentration in CuHZSM-5 and CuSAPO-34 samples which have been heated to 623 K in vacuum. Evidence is given that atleast two different sites for the copper ion location are available in the ZSM-5 structure. The laser-induced luminescence diagnosis of Cu+ ions allows a determination of the relative concentration of these sites in the samples. It provides e vidence that the concentration of sites with square pyramidal symmetry vari es linearly with the total number of Cu+ ions per unit cell. The signal int ensity of Cu is highly dependent on the site environment and especially on the Al position. Xe-129-NMR confirms the presence of Cu+ and that there is no Cu2+ interacting with Xe in the zeolite pores. (C) 2001 Elsevier Science B.V. All rights reserved.