Lean NO_<i>x</i> Capture and Reduction by NH₃ <i>via</i> NO⁺ Intermediates over H-CHA at Room Temperature

The oxidation of NO to NO2 and the subsequent reduction by NH3 via a NO+ intermediate over proton-type chabazite zeolite (H-CHA) were investigated combination in situ infrared (IR) spectroscopy density functional theory (DFT) calculations. IR spectral results indicate that species formed under flow + O2 at 27–250 °C are more stable lower temperatures both H-CHA copper-cation-exchanged CHA (Cu-CHA). Arrhenius plot (T = 27–120 °C) shows negative apparent activation barrier energy (−11.5 kJ mol–1) for formation H-CHA. time course spectra 27 is oxidized then further converted N2O4 NO3–. exposure reduces N2. DFT calculations revealed Brønsted acid sites pores promote dissociation intermediates into NO3– with low (15 mol–1). Moreover, computed was considerably (6 experimental theoretical this study demonstrate high potential Cu-free zeolites promoting lean NOx capture form room temperature.