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

Abstract

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 H2 (H2-TPR), temperature-programmed desorption of NH3 (NH3-TPD), and 27Al solid-state nuclear magnetic resonance (NMR) and diffuse reflectance Infrared Fourier Transform (DRIFT) spectroscopies. Their catalytic performance was probed using steady-state standard NH3-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 27Al 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 low- and high-temperature performance of Cu/SSZ-13 SCR catalysts.

Authors:
; ; ; ; ;
Publication Date:
Research Org.:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Environmental Molecular Sciences Lab. (EMSL)
Sponsoring Org.:
USDOE
OSTI Identifier:
1229945
Report Number(s):
PNNL-SA-111791
Journal ID: ISSN 2155-5435; 47953; 48807; VT0401000
DOE Contract Number:  
AC05-76RL01830
Resource Type:
Journal Article
Journal Name:
ACS Catalysis
Additional Journal Information:
Journal Volume: 5; Journal Issue: 11; Journal ID: ISSN 2155-5435
Publisher:
American Chemical Society
Country of Publication:
United States
Language:
English
Subject:
Selective catalytic reduction; Chabazite; SSZ-13; diesel engine emission control; Environmental Molecular Sciences Laboratory

Citation Formats

Gao, Feng, Wang, Yilin, Washton, Nancy M., Kollar, Marton, Szanyi, Janos, and Peden, Charles HF. Effects of Alkali and Alkaline Earth Cocations on the Activity and Hydrothermal Stability of Cu/SSZ-13 NH3-SCR Catalysts. United States: N. p., 2015. Web. doi:10.1021/acscatal.5b01621.
Gao, Feng, Wang, Yilin, Washton, Nancy M., Kollar, Marton, Szanyi, Janos, & Peden, Charles HF. Effects of Alkali and Alkaline Earth Cocations on the Activity and Hydrothermal Stability of Cu/SSZ-13 NH3-SCR Catalysts. United States. https://doi.org/10.1021/acscatal.5b01621
Gao, Feng, Wang, Yilin, Washton, Nancy M., Kollar, Marton, Szanyi, Janos, and Peden, Charles HF. 2015. "Effects of Alkali and Alkaline Earth Cocations on the Activity and Hydrothermal Stability of Cu/SSZ-13 NH3-SCR Catalysts". United States. https://doi.org/10.1021/acscatal.5b01621.
@article{osti_1229945,
title = {Effects of Alkali and Alkaline Earth Cocations on the Activity and Hydrothermal Stability of Cu/SSZ-13 NH3-SCR Catalysts},
author = {Gao, Feng and Wang, Yilin and Washton, Nancy M. and Kollar, Marton and Szanyi, Janos and Peden, Charles HF},
abstractNote = {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 H2 (H2-TPR), temperature-programmed desorption of NH3 (NH3-TPD), and 27Al solid-state nuclear magnetic resonance (NMR) and diffuse reflectance Infrared Fourier Transform (DRIFT) spectroscopies. Their catalytic performance was probed using steady-state standard NH3-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 27Al 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 low- and high-temperature performance of Cu/SSZ-13 SCR catalysts.},
doi = {10.1021/acscatal.5b01621},
url = {https://www.osti.gov/biblio/1229945}, journal = {ACS Catalysis},
issn = {2155-5435},
number = 11,
volume = 5,
place = {United States},
year = {Tue Oct 13 00:00:00 EDT 2015},
month = {Tue Oct 13 00:00:00 EDT 2015}
}