Effects of post-treatment method and Na co-cation on the hydrothermal stability of Cu–SSZ-13 catalyst for the selective catalytic reduction of NO  with NH3

Xie, Lijuan; Liu, Fudong; Shi, Xun; Xiao, Feng‐Shou

doi:10.1016/j.apcatb.2015.05.032

Cited by 114 publications

(62 citation statements)

References 39 publications

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“…In the last years, it has been reported that the presence of sodium cations can drastically affect the catalyst stability and activity of copper‐containing zeolites . Therefore, the absence of extra‐framework sodium cations within the BetaOH_1 catalyst could explain the improved catalytic behavior compared with the two sodium‐containing Fe‐Beta materials (>1 wt% Na, see BetaOH_2 and Beta_OH_3 in Table ) despite the fact that the deactivation mechanism is different for iron‐ and copper‐containing zeolites …”

Section: Resultsmentioning

confidence: 99%

Fe‐Containing Zeolites for NH₃‐SCR of NO_x: Effect of Structure, Synthesis Procedure, and Chemical Composition on Catalytic Performance and Stability

Martín

Vennestrøm

Thøgersen

et al. 2017

Chemistry A European J

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Abstract:The direct preparation of different Fe-containing Beta and CHA zeolites has been attempted under diverse synthesis conditions, including alkaline and fluoride media, to evaluate the influence of their physico-chemical properties on the selective catalytic reduction (SCR) of NOx using NH3 as a reductant. From the different Fe-Beta zeolites, the sample prepared in absence of alkali-cations with a Si/Al~13, shows high NO conversion values (> 90%). However, this catalyst suffers from severe deactivation when aged at high temperatures in the presence of steam. The preparation of more hydrophobic Fe-Beta zeolites does not allow improving the catalyst resistance against steaming. In contrast, the Fe-CHA material prepared by one-pot methods under alkaline conditions with a Si/Al~13 using trimethyladamantammonium as template, not only shows excellent catalytic activity but also high hydrothermal stability, especially when sodium cations are selectively removed. Moreover, a Fe-CHA synthesized using the less expensive template tetraethylammonium also results in an active and hydrothermally stable catalyst.

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Section: Resultsmentioning

confidence: 99%

Fe‐Containing Zeolites for NH₃‐SCR of NO_x: Effect of Structure, Synthesis Procedure, and Chemical Composition on Catalytic Performance and Stability

Martín

Vennestrøm

Thøgersen

et al. 2017

Chemistry A European J

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“…Therefore, it can be concluded that the cocations prevent zeolite hydrolysis during hydrothermal aging by decreasing the density of the most vulnerable acidic -Si-(OH)-Al-sites. While this conclusion is readily understandable, we emphasize here that it is still possible that excessive loadings of certain cocations may be detrimental to hydrothermal stability of zeolites, as suggested in very recent work 34. …”

mentioning

confidence: 84%

Effects of Alkali and Alkaline Earth Cocations on the Activity and Hydrothermal Stability of Cu/SSZ-13 NH₃–SCR Catalysts

et al. 2015

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Using a three-step aqueous solution ion-exchange method, cocation modified Cu/SSZ-13 SCR catalysts were synthesized. These catalysts, in both fresh and hydrothermally aged forms, were characterized with several methods including temperature-programmed reduction by H 2 (H 2 -TPR), temperature-programmed desorption of NH 3 (NH 3 -TPD), and 27 Al solid-state nuclear magnetic resonance (NMR) and diffuse reflectance Infrared Fourier Transform (DRIFT) spectroscopies. Their catalytic performance was probed using steady-state standard NH 3 -SCR. Characterization results indicate that cocations weaken interactions between Cu-ions and the CHA framework making them more readily reducible. By removing a portion of Brønsted acid sites, cocations also help to mitigate hydrolysis of the zeolite catalysts during hydrothermal aging as evidenced from 27 Al NMR. Reaction tests show that certain cocations, especially Li + and Na + , promote low-temperature SCR rates while others show much less pronounced effects. In terms of applications, our results indicate that introducing cocations can be a viable strategy to improve both lowand high-temperature performance of Cu/SSZ-13 SCR catalysts.

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“…During the synthesis of the Cu-SSZ-13 initial product, a relatively large amount of NaOH was used, and some Na + ions always were present in the final catalyst even after post-treatment by ion exchange. In order to investigate the effect of Na + ions on the NH 3 -SCR performance over Cu-SSZ-13 catalysts prepared by the onepot synthesis method, three catalysts with the same Cu content and different Na contents were prepared by Xie et al [119]. With the increase of Na + content, only a small decrease of NO x conversion was observed over the fresh Cu-SSZ-13 catalysts at low temperatures.…”

Section: One-potmentioning

confidence: 99%

“…Based on the understanding of the role of NH 4 NO 3 solution, it is believed that a dilute HNO 3 solution can also be suitable for the post-treatment of Cu-SSZ-13 catalysts, providing the proper acidic environment and necessary cations in the treating system. Thus, a new post-treatment method with dilute HNO 3 solution was further developed by Xie et al [119], which reduced the nitrogen-containing pollutants in wastewater greatly. After optimization, the optimal Cu 3.9 Na 0.8 -SSZ-13 catalyst was obtained from the post-treatment by dilute HNO 3 solution with pH = 1, which showed better NH 3 -SCR activity and hydrothermal stability than the Cu 3.8 -SSZ-13 catalyst prepared by treatment with NH 4 NO 3 solution.…”

Section: One-potmentioning

confidence: 99%

Emerging Applications of Environmentally Friendly Zeolites in the Selective Catalytic Reduction of Nitrogen Oxides

Xie

Shi

2016

Green Chemistry and Sustainable Technology

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The catalytic removal of nitrogen oxides (NO x ) from diesel exhaust under oxygen-rich conditions remains a major challenge in the field of environmental catalysis, and the selective catalytic reduction of NO x with NH 3 (NH 3 -SCR), especially over zeolite catalysts, is a well-proven technique for the catalytic deNO x process for diesel vehicles. The comprehensive understanding of the structure-activity relationship of zeolite catalysts in the NH 3 -SCR reaction and the elucidation of the detailed reaction mechanism are very important for the practical use of these catalytic materials. In this chapter, using the environmentally friendly Fe-and Cu-based zeolite catalysts (i.e. Fe-ZSM-5, Cu-ZSM-5, Cu-SSZ-13 and Cu-SAPO-34, etc.) as examples, the influence of preparation methods on NH 3 -SCR performance, the role of metal active sites/surface acid sites, the impact of NO 2 and co-existing pollutants, the hydrothermal stability and also the possible SCR reaction pathways over these materials are discussed in detail, which can provide theoretical and empirical guidance for the redesign and activity improvement of these catalysts in their practical applications.

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Effects of post-treatment method and Na co-cation on the hydrothermal stability of Cu–SSZ-13 catalyst for the selective catalytic reduction of NO with NH3

Cited by 114 publications

References 39 publications

Fe‐Containing Zeolites for NH₃‐SCR of NO_x: Effect of Structure, Synthesis Procedure, and Chemical Composition on Catalytic Performance and Stability

Fe‐Containing Zeolites for NH₃‐SCR of NO_x: Effect of Structure, Synthesis Procedure, and Chemical Composition on Catalytic Performance and Stability

Effects of Alkali and Alkaline Earth Cocations on the Activity and Hydrothermal Stability of Cu/SSZ-13 NH₃–SCR Catalysts

Emerging Applications of Environmentally Friendly Zeolites in the Selective Catalytic Reduction of Nitrogen Oxides

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Effects of post-treatment method and Na co-cation on the hydrothermal stability of Cu–SSZ-13 catalyst for the selective catalytic reduction of NO with NH3

Cited by 114 publications

References 39 publications

Fe‐Containing Zeolites for NH3‐SCR of NOx: Effect of Structure, Synthesis Procedure, and Chemical Composition on Catalytic Performance and Stability

Fe‐Containing Zeolites for NH3‐SCR of NOx: Effect of Structure, Synthesis Procedure, and Chemical Composition on Catalytic Performance and Stability

Effects of Alkali and Alkaline Earth Cocations on the Activity and Hydrothermal Stability of Cu/SSZ-13 NH3–SCR Catalysts

Emerging Applications of Environmentally Friendly Zeolites in the Selective Catalytic Reduction of Nitrogen Oxides

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Fe‐Containing Zeolites for NH₃‐SCR of NO_x: Effect of Structure, Synthesis Procedure, and Chemical Composition on Catalytic Performance and Stability

Fe‐Containing Zeolites for NH₃‐SCR of NO_x: Effect of Structure, Synthesis Procedure, and Chemical Composition on Catalytic Performance and Stability

Effects of Alkali and Alkaline Earth Cocations on the Activity and Hydrothermal Stability of Cu/SSZ-13 NH₃–SCR Catalysts