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

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.