In situ DRIFTS and temperature-programmed technology study on NH3-SCR of NOx over Cu-SSZ-13 and Cu-SAPO-34 catalysts

- The hydrothermally treated Cu-SAPO-34 is more active than Cu-SSZ-13.
- The NOx desorption levels follow the sequence: NO < NO + O2 < NO2 = NO2 + O2.
- Ammonia nitrate seems like the key intermediate in the low temperature range.
- Gas-phase NO2 seems like the key intermediate in the high temperature range.