Insights into adsorption performances and direct decomposition mechanisms of NO on [FeO]1+-ZSM-5: A density functional theory study

Abstract The density functional theory (DFT) has been employed to systematically investigate the successive adsorption performances of two NO molecules onto [FeO]1+-ZSM-5 surface and subsequent direct decomposition mechanisms by using cluster model in this paper. The adsorption results indicate that there are four stable adsorption configurations of the first NO molecule on [FeO]1+-ZSM-5, all of which are exothermic and strong chemisorption. Beginning with different adsorption configurations of first NO molecule on [FeO]1+-ZSM-5 followed by the adsorption of the second NO molecule, all four direct decomposition mechanisms are studied in which N2O molecule acts as the key reaction intermediate, N2 and O2 act as the target products. Based on thermodynamic analysis, η2-NO path that starts with adsorption of the first NO as O-down and follows the Eley-Rideal mechanism is proposed, in which ONNO species and N2O are the key catalytic intermediates. The full catalytic reaction is exothermic by 43.76 kcal/mol. The rate-determining step is the formation of N2(ads), i.e. N2O(ads)→N2(ads) +O(ads) and its barrier energy is 39.09 kcal/mol.