Synergistic effect between the acidity and redox performance of the SO42−-CeO2 catalysts for NO reduction

Herein, a series of SO42−-CeO2 catalysts were synthesized by a sol-gel method for the selective catalytic reduction of NO by NH3 (NH3-SCR). The introduction of SO42− endowed composite catalyst with higher catalytic activity than pure CeO2. In particular, 3% SC with 3% SO42− showed over 90% NO removal between 247 and 450 °C. SO42− promoted the increase of Ce3+ content, adsorbed oxygen, and surface acidity of the composites. Furthermore, the interaction between SO42− and cerium oxide induced the synergistic effect between acidic sites and redox sites in the NH3-SCR reaction. The introduction of SO42− significantly supported the increase of B-acid and the enhancement of l-acid sites, and promoted the NH3-SCR reaction to follow both Eley-Rideal and Langmuir-Hinshelwood mechanisms.