New Insights into the Effect of Ce Doping on the Catalytic Performance and Hydrothermal Stability of Cu-USY Zeolite Catalysts for the Selective Catalytic Reduction of NO with NH<sub>3</sub>
5Cu-USY and Ce-doped 5Cu8Ce-USY zeolite catalysts were prepared by the conventional impregnation method. The obtained catalysts were subjected to the hydrothermal ageing process. The catalytic performance of the selective catalytic reduction of NO<i><sub>x</sub></i> with NH&l...
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MDPI AG
2023-11-01
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| Online Access: | https://www.mdpi.com/2073-4344/13/12/1485 |
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| author | Qi Sun Haipeng Yang Jie Wan Wanru Hua Yanjun Liu Xiaoli Wang Chunxiao Shi Qingai Shi Gongde Wu Renxian Zhou |
| author_facet | Qi Sun Haipeng Yang Jie Wan Wanru Hua Yanjun Liu Xiaoli Wang Chunxiao Shi Qingai Shi Gongde Wu Renxian Zhou |
| author_sort | Qi Sun |
| collection | DOAJ |
| description | 5Cu-USY and Ce-doped 5Cu8Ce-USY zeolite catalysts were prepared by the conventional impregnation method. The obtained catalysts were subjected to the hydrothermal ageing process. The catalytic performance of the selective catalytic reduction of NO<i><sub>x</sub></i> with NH<sub>3</sub> (NH<sub>3</sub>-SCR) was evaluated on both fresh and aged catalysts. Physical/chemical characterizations such as X-ray diffraction (XRD), H<sub>2</sub> temperature-programmed reduction (H<sub>2</sub>-TPR), and X-ray photoelectron spectroscopy (XPS) were performed, along with detailed in situ diffuse reflectance infrared Fourier-transform spectroscopy (DRIFTS) experiments including CO adsorption, NH<sub>3</sub> adsorption, and NO + O<sub>2</sub> reactions. Results showed that, for the 5Cu-USY catalyst, hydrothermal ageing treatment could somehow improve the low-temperature SCR activity, but it also led to significant formation of unfavorable byproducts NO<sub>2</sub> and N<sub>2</sub>O. Such an activity change can be attributed to hydrothermal ageing inducing the migration of isolated Cu<sup>+</sup> species in the sodalite cavities towards the super cages of the USY zeolites. The increased content of Cu<sup>+</sup> species in the super cages was beneficial for the low-temperature activity improvement, but, at the same time, it also facilitated ammonia oxidation at high temperatures. Ce doping after hydrothermal ageing has a “double-edged sword” effect on the catalytic performance. First of all, Ce doping can inhibit Cu species migration by self-occupying the internal cage sites; thus, the catalytic performance of 5Cu8Ce-USY-700H remains stable after ageing. Secondly, Ce doping introduces a CuO<sub>x</sub>–CeO<sub>2</sub> strong interaction, which facilitates lattice oxygen mobility by forming more oxygen vacancies so as to increase the concentration of surface active oxygen. These changes, on the one hand, could help to promote further oxidative decomposition of nitrate/nitrite intermediates and improve the catalytic performance. But, on the other hand, it also causes the byproduct generation to become more severe. |
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| issn | 2073-4344 |
| language | English |
| last_indexed | 2024-03-08T20:54:49Z |
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| spelling | doaj.art-81da58543cbf486cb62dc7d9b66ffb862023-12-22T13:59:25ZengMDPI AGCatalysts2073-43442023-11-011312148510.3390/catal13121485New Insights into the Effect of Ce Doping on the Catalytic Performance and Hydrothermal Stability of Cu-USY Zeolite Catalysts for the Selective Catalytic Reduction of NO with NH<sub>3</sub>Qi Sun0Haipeng Yang1Jie Wan2Wanru Hua3Yanjun Liu4Xiaoli Wang5Chunxiao Shi6Qingai Shi7Gongde Wu8Renxian Zhou9Energy Research Institute, Nanjing Institute of Technology, Nanjing 211167, ChinaInstitute of Catalysis, Zhejiang University, Hangzhou 310028, ChinaEnergy Research Institute, Nanjing Institute of Technology, Nanjing 211167, ChinaSchool of Environmental Engineering, Nanjing Institute of Technology, Nanjing 211167, ChinaEnergy Research Institute, Nanjing Institute of Technology, Nanjing 211167, ChinaSchool of Environmental Engineering, Nanjing Institute of Technology, Nanjing 211167, ChinaZhejiang NHU Co., Ltd., Shaoxing 312500, ChinaZhejiang NHU Co., Ltd., Shaoxing 312500, ChinaEnergy Research Institute, Nanjing Institute of Technology, Nanjing 211167, ChinaInstitute of Catalysis, Zhejiang University, Hangzhou 310028, China5Cu-USY and Ce-doped 5Cu8Ce-USY zeolite catalysts were prepared by the conventional impregnation method. The obtained catalysts were subjected to the hydrothermal ageing process. The catalytic performance of the selective catalytic reduction of NO<i><sub>x</sub></i> with NH<sub>3</sub> (NH<sub>3</sub>-SCR) was evaluated on both fresh and aged catalysts. Physical/chemical characterizations such as X-ray diffraction (XRD), H<sub>2</sub> temperature-programmed reduction (H<sub>2</sub>-TPR), and X-ray photoelectron spectroscopy (XPS) were performed, along with detailed in situ diffuse reflectance infrared Fourier-transform spectroscopy (DRIFTS) experiments including CO adsorption, NH<sub>3</sub> adsorption, and NO + O<sub>2</sub> reactions. Results showed that, for the 5Cu-USY catalyst, hydrothermal ageing treatment could somehow improve the low-temperature SCR activity, but it also led to significant formation of unfavorable byproducts NO<sub>2</sub> and N<sub>2</sub>O. Such an activity change can be attributed to hydrothermal ageing inducing the migration of isolated Cu<sup>+</sup> species in the sodalite cavities towards the super cages of the USY zeolites. The increased content of Cu<sup>+</sup> species in the super cages was beneficial for the low-temperature activity improvement, but, at the same time, it also facilitated ammonia oxidation at high temperatures. Ce doping after hydrothermal ageing has a “double-edged sword” effect on the catalytic performance. First of all, Ce doping can inhibit Cu species migration by self-occupying the internal cage sites; thus, the catalytic performance of 5Cu8Ce-USY-700H remains stable after ageing. Secondly, Ce doping introduces a CuO<sub>x</sub>–CeO<sub>2</sub> strong interaction, which facilitates lattice oxygen mobility by forming more oxygen vacancies so as to increase the concentration of surface active oxygen. These changes, on the one hand, could help to promote further oxidative decomposition of nitrate/nitrite intermediates and improve the catalytic performance. But, on the other hand, it also causes the byproduct generation to become more severe.https://www.mdpi.com/2073-4344/13/12/1485NH<sub>3</sub>-SCRCu-USYCeria dopinghydrothermal stabilityDRIFTS |
| spellingShingle | Qi Sun Haipeng Yang Jie Wan Wanru Hua Yanjun Liu Xiaoli Wang Chunxiao Shi Qingai Shi Gongde Wu Renxian Zhou New Insights into the Effect of Ce Doping on the Catalytic Performance and Hydrothermal Stability of Cu-USY Zeolite Catalysts for the Selective Catalytic Reduction of NO with NH<sub>3</sub> Catalysts NH<sub>3</sub>-SCR Cu-USY Ceria doping hydrothermal stability DRIFTS |
| title | New Insights into the Effect of Ce Doping on the Catalytic Performance and Hydrothermal Stability of Cu-USY Zeolite Catalysts for the Selective Catalytic Reduction of NO with NH<sub>3</sub> |
| title_full | New Insights into the Effect of Ce Doping on the Catalytic Performance and Hydrothermal Stability of Cu-USY Zeolite Catalysts for the Selective Catalytic Reduction of NO with NH<sub>3</sub> |
| title_fullStr | New Insights into the Effect of Ce Doping on the Catalytic Performance and Hydrothermal Stability of Cu-USY Zeolite Catalysts for the Selective Catalytic Reduction of NO with NH<sub>3</sub> |
| title_full_unstemmed | New Insights into the Effect of Ce Doping on the Catalytic Performance and Hydrothermal Stability of Cu-USY Zeolite Catalysts for the Selective Catalytic Reduction of NO with NH<sub>3</sub> |
| title_short | New Insights into the Effect of Ce Doping on the Catalytic Performance and Hydrothermal Stability of Cu-USY Zeolite Catalysts for the Selective Catalytic Reduction of NO with NH<sub>3</sub> |
| title_sort | new insights into the effect of ce doping on the catalytic performance and hydrothermal stability of cu usy zeolite catalysts for the selective catalytic reduction of no with nh sub 3 sub |
| topic | NH<sub>3</sub>-SCR Cu-USY Ceria doping hydrothermal stability DRIFTS |
| url | https://www.mdpi.com/2073-4344/13/12/1485 |
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