A facile and controllable in situ sulfation strategy for CuCeZr catalyst for NH3-SCR

The Cu-based transition-metal-oxide catalysts were widely applied for the selective catalytic reduction of NOx with NH3 (NH3-SCR), but limited in practical application because of the inferior catalytic performance at high temperatures. To counter this issue, we designed a facile in situ strategy to obtain sulfated CuCeZr catalysts, on which the sulfation degree could be precisely controlled without any further post-treatment. The sulfated CuCeZr catalysts not only show broader SCR reaction temperature window and promoted N-2 selectivity, but also demonstrate satisfactory tolerance to H2O and SO2. The outcomes indicate that stronger surface acidity, weaker reducibility and excellent stability for adsorbing NH3 on the sulfated CuCeZr catalysts greatly suppress the undesired excessive oxidation of NH3 at high temperatures, which enhance the high-temperature activity and N-2 selectivity. Furthermore, the transient in situ DRIFT and steady-state kinetic studies reveal that both unsulfated and sulfated catalysts mainly follow the Eley-Rideal mechanism.