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 Ce 3+ and CeO 2 nanoparticle is located on the surface of Cu/SAPO-34, and Ce 3+ 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 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. Ce ions play a vital role on protecting CHA structure integrity. The fragile structure can lead to the loss of extra-large amounts of Cu(II) ions, degrade of SCR activity. The intact structure is conducive to the protection of Cu(II) ions and the further recovery of SCR activity after regeneration. • Cerium as Ce 3+ and CeO 2 nanoparticle is only located on the surface of Cu/SAPO-34. • Ce 3+ plays a vital role on decreasing surface acidity and blocking defect sites. • Low surface acidity stabilizes structure during low-temperature hydrothermal aging. • The structure's stability prevents the number of Cu(II) ions from largely decreasing. • The structure's stability helps the recovery of Cu(II) ions during regeneration.