Superior PbO-resistance of CeO2/ZrO2 catalyst promoted by solid superacid SO42-/ZrO2 for selective catalytic reduction of NOx with NH3

The serious deactivation of denitration catalysts caused by heavy metals still a thorny issue in the practical application of selective catalytic reduction of NOx with NH3. Herein, we proposed a novel anti-poisoning strategy by designing SO42-/ZrO2 superacid supported CeO2/ZrO2 catalyst, and the effect of SO42-/ZrO2 supported CeO2/ ZrO2 for PbO-resistance NOx catalytic reduction was investigated. It was worthy to note that the introduction of solid superacid SO42-/ZrO2 significantly enhanced catalytic performance over the entire temperature range, with an exceptionally high NOx removal efficiency over 98 % during 250-500 degrees C. When 2 wt% PbO was deposited on the fresh catalyst, the catalytic activity of CeO2/ZrO2 catalyst decreased obviously, while CeO2/ZrO2-S catalyst can still maintain a higher NOx conversion over 90 % from 275 to 500 degrees C. The characterization results confirmed that the introduction of solid superacid SO42-/ZrO2 enhanced the surface acidity and promoted the trans-formation from Ce4+ to Ce3+. The results of in situ DRIFTS implied that the Eley-Rideal (E-R) mechanism was obeyed over CeO2/ZrO2 catalyst, and both Eley-Rideal (E-R) and Langmuir-Hinshelwood (L-H) mechanisms were followed over CeO2/ZrO2-S catalyst in the SCR process. With regard to poisoned catalysts, the NH3 adsorption was inhibited to some extent, while the reaction mechanism wasn't changed by PbO poisoning.

Automated summary

The deactivation of denitration catalysts by heavy metals is still a challenge in the practical application of selective catalytic reduction of NOx with NH3. In this study, a novel anti-poisoning strategy was proposed by designing a CeO2/ZrO2 catalyst supported by SO42-/ZrO2 superacid. The introduction of SO42-/ZrO2 significantly enhanced the catalytic performance, leading to high NOx removal efficiency throughout a wide temperature range.