ISSN:
1572-879X
Keywords:
H+-induced reoxidation
;
Cu/Na-ZSM-5
;
CO
;
FTIR
;
TPR-TPD
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
Notes:
Abstract TPR/TPD and FTIR are used to characterize “excessively ion-exchanged” Cu/Na-ZSM-5. After calcination in O2 at 773 K at least two copper-oxygen species are present in addition to Cu2+ ions; these have been identified as CuO and [Cu-O-Cu]2+. Reduction in H2 transforms all these into Cu0 below 773 K. [Cu-O-Cu]2+ is autoreduced to Cu+ during outgassing. Reoxidation of Cu0 by zeolite protons to Cu+ is observed above 723 K in He or Ar; in the presence of CO this process is considerably enhanced and observed at much lower temperature, because CO is strongly adsorbed on Cu+. At 293 K CO adsorption causes reversible changes in the FTIR spectra.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00764336
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