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Title: Thermal Durability of Cu-CHA NH3-SCR Catalysts for Diesel NOx Reduction

Abstract

Multiple catalytic functions (NOx conversion, NO and NH3 oxidation, NH3 storage) of a commercial Cu-zeolite urea/NH3-SCR catalyst were assessed in a laboratory fixed-bed flow reactor system after differing degrees of hydrothermal aging. Catalysts were characterized by using x-ray diffraction (XRD), 27Al solid state nuclear magnetic resonance (NMR) and transmission electron microscopy (TEM) / energy dispersive X-ray (EDX) spectroscopy to develop an understanding of the degradation mechanisms during catalyst aging. The catalytic reaction measurements of laboratory-aged catalysts were performed, which allows us to obtain a universal curve for predicting the degree of catalyst performance deterioration as a function of time at each aging temperature. Results show that as the aging temperature becomes higher, the zeolite structure collapses in a shorter period of time after an induction period. The decrease in SCR performance was explained by zeolite structure destruction and/or Cu agglomeration, as detected by XRD/27Al NMR and by TEM/EDX, respectively. Destruction of the zeolite structure and agglomeration of the active phase also results in a decrease in the NO/NH3 oxidation activity and the NH3 storage capacity of the catalyst. Selected laboratory aging conditions (16 h at 800oC) compare well with a 135,000 mile vehicle-aged catalyst for both performance and characterization criteria.

Authors:
; ; ; ; ; ;
Publication Date:
Research Org.:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Environmental Molecular Sciences Lab. (EMSL)
Sponsoring Org.:
USDOE
OSTI Identifier:
1039118
Report Number(s):
PNNL-SA-84104
Journal ID: ISSN 0920-5861; CATTEA; 35404; VT0401000; TRN: US201209%%181
DOE Contract Number:  
AC05-76RL01830
Resource Type:
Journal Article
Journal Name:
Catalysis Today
Additional Journal Information:
Journal Volume: 184; Journal Issue: 1; Journal ID: ISSN 0920-5861
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; AGGLOMERATION; AGING; CAPACITY; CATALYSTS; INDUCTION; NUCLEAR MAGNETIC RESONANCE; OXIDATION; PERFORMANCE; SPECTROSCOPY; STORAGE; TRANSMISSION ELECTRON MICROSCOPY; X-RAY DIFFRACTION; ZEOLITES; NITROGEN OXIDES; Environmental Molecular Sciences Laboratory

Citation Formats

Schmieg, Steven J, Oh, Se H, Kim, Chang H, Brown, David B, Lee, Jong H, Peden, Charles HF, and Kim, Do Heui. Thermal Durability of Cu-CHA NH3-SCR Catalysts for Diesel NOx Reduction. United States: N. p., 2012. Web. doi:10.1016/j.cattod.2011.10.034.
Schmieg, Steven J, Oh, Se H, Kim, Chang H, Brown, David B, Lee, Jong H, Peden, Charles HF, & Kim, Do Heui. Thermal Durability of Cu-CHA NH3-SCR Catalysts for Diesel NOx Reduction. United States. https://doi.org/10.1016/j.cattod.2011.10.034
Schmieg, Steven J, Oh, Se H, Kim, Chang H, Brown, David B, Lee, Jong H, Peden, Charles HF, and Kim, Do Heui. 2012. "Thermal Durability of Cu-CHA NH3-SCR Catalysts for Diesel NOx Reduction". United States. https://doi.org/10.1016/j.cattod.2011.10.034.
@article{osti_1039118,
title = {Thermal Durability of Cu-CHA NH3-SCR Catalysts for Diesel NOx Reduction},
author = {Schmieg, Steven J and Oh, Se H and Kim, Chang H and Brown, David B and Lee, Jong H and Peden, Charles HF and Kim, Do Heui},
abstractNote = {Multiple catalytic functions (NOx conversion, NO and NH3 oxidation, NH3 storage) of a commercial Cu-zeolite urea/NH3-SCR catalyst were assessed in a laboratory fixed-bed flow reactor system after differing degrees of hydrothermal aging. Catalysts were characterized by using x-ray diffraction (XRD), 27Al solid state nuclear magnetic resonance (NMR) and transmission electron microscopy (TEM) / energy dispersive X-ray (EDX) spectroscopy to develop an understanding of the degradation mechanisms during catalyst aging. The catalytic reaction measurements of laboratory-aged catalysts were performed, which allows us to obtain a universal curve for predicting the degree of catalyst performance deterioration as a function of time at each aging temperature. Results show that as the aging temperature becomes higher, the zeolite structure collapses in a shorter period of time after an induction period. The decrease in SCR performance was explained by zeolite structure destruction and/or Cu agglomeration, as detected by XRD/27Al NMR and by TEM/EDX, respectively. Destruction of the zeolite structure and agglomeration of the active phase also results in a decrease in the NO/NH3 oxidation activity and the NH3 storage capacity of the catalyst. Selected laboratory aging conditions (16 h at 800oC) compare well with a 135,000 mile vehicle-aged catalyst for both performance and characterization criteria.},
doi = {10.1016/j.cattod.2011.10.034},
url = {https://www.osti.gov/biblio/1039118}, journal = {Catalysis Today},
issn = {0920-5861},
number = 1,
volume = 184,
place = {United States},
year = {Mon Apr 30 00:00:00 EDT 2012},
month = {Mon Apr 30 00:00:00 EDT 2012}
}