Enhancement of nitric oxide reduction via CeZrOx/Cu-SSZ-39 hybrid catalyst: Improving activity and hydrothermal stability

This study aimed to improve the catalytic activity and hydrothermal stability of Cu-SSZ-39 zeolite by coupling it with cerium zirconium oxides (CeZrOx), which possesses excellent oxidizing ability, and a hybrid catalyst CeZrOx/Cu-SSZ-39 was prepared. It is found that it exhibited enhanced low-temperature activity, high-temperature activity, and a wider effective temperature range compared to Cu-SSZ-39. Characterization results showed that the CeZrOx/Cu-SSZ-39 catalyst had a higher concentration of active Cu2+ ion species and improved redox properties, which could potentially promote the NH3-SCR reaction. Additionally, the CeZrOx/Cu-SSZ-39 catalyst had increased chemisorbed oxygen species on its surface, facilitating the oxidation of NO to NO2 and enhancing the rate of the SCR reaction. Moreover, even after undergoing hydrothermal aging treatment, the CeZrOx/Cu-SSZ-39 catalyst exhibited superior catalytic activity and improved hydrothermal stability, surpassing the performance of Cu-SSZ-39. It is found the CeZrOx coupling allowed the hybrid catalyst to maintain a better specific surface area and pore structure during hydrothermal aging, resulting in reduced activity loss. Therefore, the addition of CeZrOx enhanced the NH3-SCR activity of Cu-SSZ-39 zeolite, leading to improved catalytic activity and hydrothermal stability. CeZrOx/Cu-SSZ-39 catalyst has shown promising aspect for reducing NOx emissions from diesel vehicle exhaust.