Raman and IR spectroscopy data

The dealumination process in mordenite has been analyzed by XRD, IR, and NMR methods [97L1]. The IR band shift of = 572 and 588 cm to higher wavelengths and the decrease of the band intensity at 650 cm and 730 cm with decreasing A1 content indicate a dealumination process. By using e NMR, it was shown that the extra-framework aluminum may interrupt the fiee exchange of molecules between the main channels and side pockets. 

The desilication process of mordenite was also evaluated by FTIR spectroscopy [lOPlJ. A shift of lattice vibration bands toward smaller wave numbers was shown upon alkaline treatment. Consequently, this evolution can be taken as evidence of the silicon removal. A linear correlation between the number of framework Si per unit cell, Nsi, and the asymmetric stretching wave nmnber, Vi, was observed vi [cm ] = 20.2 Nsi+ 193.0 [lOPl], The desilicated samples exhibit the same acidic properties as the parent H-MOR zeolite. 

The concentration of A1 and Fe isomorphously substituting silicon in the frameworks of mordenite, ferrierite, ZSM-5, and ZSM-22, as well as in other zeolites were determined in NH4 and dehydrated/deammoniated forms by IR and Al NMR [01B3]. It has been shown that the intensity of N-H vibration at 1445 cm of fully exchanged NH4-zeolites with the determined extinction coefficient represented a quantitative measure of the concentration of NH4 ions and, accordingly, the concentration of A1 and Fe in the fiamework positions of the hydrated zeolites [01B3]. 

The H-form and Pd-containing mordenites were studied by FTIR [06KI], The same typical bands in natural and H-form zeolites were fonnd. 

Fe-modified ferrierite and MFI-zeolite structures were analyzed by UV-vis spectroscopy [10S3]. The Fe cationic and Fe oxidic species were identified. 

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