Effect of copper precursor on simultaneous removal of PM and NOx of a 2-way SCR/CDPF

• 5 wt% Cu exchanged Beta and ZSM-5 zeolites tested in 2-way SCR/CDPF systems.
• Cu precursors(Cu(II) sulfate and Cu(II) chloride) were used for the SCR catalysts.
• Beta based catalysts resulted in higher activity than ZSM-5, related with formation of CuO.
• Cu(II) chloride based catalyst resulted in higher activity, related with Cu species.

The purpose of this study is to analyze the effect of Cu-precursors for a Selective Catalytic Reduction (SCR) catalyst on the de-NOx and de-PM performance of a 2-way SCR/DPF. For the SCR catalyst in the Diesel Particulate Filter (DPF) substrate, beta zeolite (BEA) was used as the catalyst support and Cu as the main catalyst. In this case, copper (II) sulfate and copper (II) chloride were used as the Cu-precursors. A model gas reactor was used to evaluate the performance of the catalyst, and Fourier Transform Infrared (FTIR) spectrometry was used to analyze the concentrations of nitrogen oxides (NOx), ammonia NH3, and other gases. The result from one experiment indicated that the NOx conversion of the fresh CuSO4–BEA catalyst was similar to that of the fresh CuCl2–BEA catalyst. However, after hydrothermal aging, the NOx conversion of the CuCl2–BEA catalyst was much higher than that of the CuSO4–BEA catalyst. These findings indicate that the CuCl2–BEA catalyst had outstanding durability, which was analyzed to verify the structure of the catalyst and its chemical changes. Varieties of ion-exchanged copper types were observed in the zeolite catalyst support, implying that the activation of the catalyst was mainly due to copper. The CuCl2–BEA catalyst also showed superior PM oxidation performance compared to the other SCR/DPF catalysts.

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