DENSITY-FUNCTIONAL CALCULATION ON THE ADSORPTION OF NITROGEN-OXIDES AND WATER ON ION-EXCHANGED ZSM-5

Removal of nitrogen oxides (NOx) from exhaust gases in the presence of excess oxygen is a major problem. Our work is aimed in a direction to propose effective catalyst for NOx removal. Configuration and electro nic states of adsorbed NOx species on various ion exchanged ZSM-5 have been investigated by quantum chemical calculation based on Density Fu nctional Theory (DFT). In case of NO adsorption on monovalent and diva lent metal cations, nitrogen atom of NO molecule interacts with exchan ged metal cations. Whereas in case of the trivalent metal cations extr aframework oxygen is also involved along with the exchanged cations in adsorption process. NO2 and H2O adsorption over exchanged metal catio n were also studied. Different combination of exchangeable metal catio ns over NOx adsorption was studied. Large affinity of NOx was observed , when Cu+, (Fe-OH)(+), (Co-OH)(+), (In-O)(+), (Tl-O)(+) are present i n ZSM-5 as exchanged cations. (C) 1998 Elsevier Science B.V. All right s reserved.