Zinc and phosphorus poisoning tolerance of Cu-SSZ-13 and Ce-Cu-SSZ-13 in the catalytic reduction of nitrogen oxides
2023
Song, Kunli | Zhao, Shuqi | Li, Zhenguo | Li, Kaixiang | Xu, Yurong | Zhang, Yijun | Cheng, Yonghong | Shi, Jian-Wen
SSZ-13 has been commercialized as a catalyst in diesel engines for the selectivity catalytic reduction of nitrogen oxides (NOₓ) with ammonia (NH₃-SCR), but the catalyst is facing the problem of poisoning. Herein, two well-designed catalysts, Cu-SSZ-13 and cerium (Ce) doped Cu-SSZ-13 are synthesized, and their tolerance to zinc (Zn) and phosphorus (P) poisoning alone and together are explored in detail. The research found that Zn and P poisoning alone leads to the destruction of Cu-SSZ-13 structure, resulting in the decline of denitration (de-NOₓ) performance following the mechanism dominated by Eley-Rideal (E-R). Surprisingly, it is found that zinc phosphate particles are formed at inactive sites on the surface of Cu-SSZ-13 in the presence of Zn and P together, which protects the active sites, enhances the adsorption of nitric oxide. As a result, the excellent de-NOₓ performance of Cu-SSZ-13 is well maintained following the dual mechanism of E-R and Langmuir-Hinshelwood (L-H). In addition, the introduction of Ce stabilizes the active sites, so as to improve the de-NOₓ performance and the poisoning tolerance of Cu-SSZ-13. This work deeply analyzes the reasons of Zn and P poisoning and the positive effect of Ce on Cu-SSZ-13, which provides ideas for improving the poisoning tolerance of Cu-SSZ-13 and promotes the further application.
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