1. Ion Exchange of One-Pot Synthesized Cu-SAPO-44 with NH4NO3 to Promote Cu Dispersion and Activity for Selective Catalytic Reduction of NOx with NH3.
- Author
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Zhang, Nana, Xin, Ying, Li, Qian, Ma, Xicheng, Qi, Yongxin, Zheng, Lirong, and Zhang, Zhaoliang
- Subjects
SELECTIVE catalytic oxidation ,ION exchange (Chemistry) ,CATALYTIC reduction ,TRANSMISSION electron microscopes ,X-ray powder diffraction ,SCANNING electron microscopes ,COPPER powder - Abstract
Cu-containing CHA type (Cu-CHA) zeolites have been widely investigated owing to their excellent low-temperature activity and high hydrothermal stability in selective catalytic reduction of NO
x with NH3 (NH3 -SCR). Herein, a series of Cu-SAPO-44 zeolites were prepared by one-pot method with dual-amine templates and the subsequent ion exchange (IE) with NH4 NO3 . The effect of NH4 NO3 treatment on Cu species was investigated by X-ray powder diffraction (XRD), N2 adsorption-desorption isotherm, inductively coupled plasma (ICP); field-emission scanning electron microscope (FE-SEM), high-resolution transmission electron microscope (HRTEM), X-ray absorption fine structure (XAFS), and H2 -temperature-programmed reduction (H2 -TPR). The results indicated that—besides the main SAPO-44 structure—the CuO phase was detected by XRD in original samples. After IE with NH4 NO3 , the Cu contents decreased greatly from ICP analysis. The removal of CuO agglomerations and the presence of highly dispersed CuO nanoparticles (~2.36 nm) were confirmed by SEM, TEM and H2 -TPR. Furthermore, a significant increase in the proportion of isolated Cu2+ was derived from XAFS. As a result, the activity at higher temperature (≥350 °C) was improved a lot. [ABSTRACT FROM AUTHOR]- Published
- 2019
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