Operando IR and in situ XAFS-DRIFTS studies on selective catalytic reduction of N2O by CH4 in NO- and NH3-containing atmospheres

In this study, Fe-beta zeolite was adopted as a model catalyst to investigate the catalytic activity and reaction mechanism under simulated exhaust from the NH 3 -CH 4 co-firing process, which includes NO, N 2 O, NH 3 , CH 4 , and O 2 . The reaction between N 2 O and CH 4 proceeded at 300 °C but required higher temperatures in the presence of NH 3 or NO. Operando infrared (IR) spectroscopy and in situ X-ray absorption near-edge structure combined with diffuse reflectance infrared Fourier transform spectroscopy (XANES-DRIFTS) were used to elucidate the effects of NO and NH 3 on the formation of Fe(III)-OH and α-oxygen (αO) species from the activation of N 2 O at Fe(II) sites. Both NH 3 and NO were preferentially adsorbed on Fe(II) and reacted more readily with Fe(III)-OH and αO than CH 4 . NH 3 exhibited strong adsorption on Fe(II), thereby inhibiting further generation of active oxygen species from N 2 O. In contrast, NO adsorption was weaker and N 2 O activation could still occur. CH 4 was only able to react with Fe(III)-OH and αO species in the absence of NH 3 and NO. • Different SCR reaction activity of Fe-beta catalyst was tested. • Reaction pathway between N 2 O and CH 4 on Fe-beta was revealed. • NO and NH 3 inhibited the activation of N 2 O on Fe(II) sites. • Fe(III)-OH and α-oxygen reacted preferentially with NO and NH 3 rather than CH 4 .