Unraveling the nature of cerium on stabilizing Cu/SAPO-34 NH3-SCR catalysts under hydrothermal aging at low temperatures

To reveal how cerium stabilizes Cu/SAPO-34 at low-temperature hydrothermal aging, various amounts of cerium were introduced into Cu/SAPO-34 via impregnation method and treated at 70 °C with RH 80% for 96 h. Cerium as Ce3+ and CeO2 nanoparticle is located on the surface of Cu/SAPO-34, and Ce3+ plays a vital role on gradually decreasing surface acidity and blocking defect sites with an increase of Ce loading. After hydrothermal aging, Cu/SAPO-34 with high Ce loading shows the superior SCR activity comparable to fresh samples. It is proven that the surface acidity determines the stability of the structure during hydrothermal aging process, and lower surface acidity prevents the number of Cu(II) ions from decreasing significantly. Furthermore, the structure's stability helps the recovery of Cu(II) ions and renders an outstanding regeneration ability. Our finding paves the way for the design of new Cu/SAPO-34 catalysts with good SCR activity and long-term stability in real application.