Adsorption properties of nitrogen monooxide on metal ion-exchanged zeolites

The adsorption properties of nitrogen monooxide (NO) on various metal ion-exchanged zeolites were examined by adsorption-desorption measurement in a fixed bed flow apparatus. The amounts of reversible (q(rev)) and irreversible (q(irr)) adsorption of NO were changed with the types of metal ion and zeolite structure. Among the samples tested, the copper ion-exchanged ZSM-5 and silver ion-exchanged mordenite showed the greatest ability for reversible adsorption of NO. The amounts of reversible and irreversible adsorption of NO per metal ion exchanged increased with decreasing aluminum content of zeolites, and were constant, independent of the ion exchange level for ZSM-5 zeolites, but changed with the ion exchange level for mordenite zeolites. It has also been found that the adsorption properties are dependent on adsorption temperature: q(irr) increased with decreasing adsorption temperature for both copper and silver ion exchanged zeolites, however, q(rev) of Cu-ZSM-5 showed a maximum at 243 K, and q(rev) of Ag-MOR increased with decreasing adsorption temperature.