EPR study on NO introduced into lithium ion-exchanged LTA zeolites

Abstract

Nitrogen monoxide (NO) introduced into partially and fully lithium ion (Li + )-exchanged A-type zeolite was studied by X-band EPR measurements. Two types of NO species, NO monoradical and NO-NO biradical, were detected for the partially ion-exchanged zeolite, while the latter was less detectable for the fully ion-exchanged one. The EPR parameters of the NO monoradical provided evidence that the electrostatic field associated with Li + ions in A-type zeolites is weaker than that with Na + ions. It was found that the molecular distance of NO biradical formed in partially Li + -exchanged zeolite was shorter than that in sodium ion-exchanged A-type zeolite.

Interaction of CH2OH with silver cation in Ag–A/CH3OH zeolite: A DFT study

“…They can form complexes with many organic molecules -including radicals or ions. Such processes are based on specific interactions between the adsorbates and exchangeable cations [8][9][10][11][12][13][14][15].…”

Adsorption of NO in Li-exchanged zeolite A. A density functional theory study

“…Unfortunately precise experimental values of g 2 ; g 3 ; A N 2 and A N 3 were not determined due to the superposition of signals of two different NO monoradicals in Li + exchanged zeolite Na-A [6].…”

“…X-band studies of nitrogen monoxide adsorbed on partially and fully Li-exchanged A-type zeolites indicate also the presence of NO monoradical and (NO) 2 biradical. However, the electrostatic field associated with Li + ions in zeolites A is weaker compared to that observed in the Na + exchanged zeolites [6].…”

“…Thus, the nature of the interaction of NO x with metal ions in zeolites has been investigated by electron paramagnetic resonance (EPR) during the last few decades [2][3][4]. Both NO and NO 2 nitrogen oxides have been used as EPR probes for studying catalytic decomposition of nitric oxides in zeolites, in which they simultaneously are reaction intermediates [5,6]. Lunsford reported EPR spectra of NO adsorbed on Na-FAU(Y) and NH 4 -FAU(Y) zeolites [7].…”

“…In the present study, we report an analysis of the system experimentally characterized by Yahiro and co-workers [6]. Because of the lack of detailed EPR data for such systems, the calculated hyperfine splittings were also compared with experimental data for related complexes.…”