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Title: Water-induced Bulk Ba(NO3)2 Formation From NO2 Exposed Thermally Aged BaO/Al2O3

Abstract

Phase changes in high temperature treated (> 900 °C) 8 or 20 wt% BaO supported on Al2O3 model lean NOx trap (LNT) catalysts, induced by NO2 and/or H2O adsorption, were investigated with powder X-ray Diffraction (XRD), solid state 27Al Magic Angle Spinning Nuclear Magnetic Resonance (MAS NMR) spectroscopy, and NO2 Temperature Programmed Desorption (TPD) experiments. After calcination in dry air at 1000 °C, the XRD and solid state 27Al MAS NMR results confirm that stable surface BaO and bulk BaAl2O4 phases are formed for 8 and 20 wt% BaO/Al2O3, respectively. Following NO2 adsorption over these thermally treated samples, no additional phase changes are observed based on XRD results. However, when water was added to the thermally aged samples after NO2 exposure, the formation of crystalline Ba(NO3)2 particles was observed in both samples. Solid state 27Al MAS NMR is shown to be a good technique for identifying the various Al species present in the materials during the processes studied here. NO2 TPD results demonstrate a significant loss of uptake for the 20 wt% model catalysts upon thermal treatment. However, the described phase transformations upon subsequent water treatment gave rise to the partial recovery of NOx uptake, demonstrating that such a watermore » treatment of thermally aged catalysts can provide a potential method to regenerate LNT materials.« less

Authors:
; ; ; ;
Publication Date:
Research Org.:
Pacific Northwest National Laboratory (PNNL), Richland, WA (US), Environmental Molecular Sciences Laboratory (EMSL)
Sponsoring Org.:
USDOE
OSTI Identifier:
908943
Report Number(s):
PNNL-SA-50942
Journal ID: ISSN 0926-3373; ACBEE3; 19800; VT0401000; TRN: US200722%%825
DOE Contract Number:  
AC05-76RL01830
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Catalysis. B, Environmental; Journal Volume: 72; Journal Issue: 3-4
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; BARIUM NITRATES; SYNTHESIS; BARIUM OXIDES; NITROGEN DIOXIDE; PHASE STUDIES; PHASE TRANSFORMATIONS; CATALYSTS; REGENERATION; NOx storage; barium aluminate; barium nitrate; XRD; solid state 27Al MAS NMR; NO2 TPD; Environmental Molecular Sciences Laboratory

Citation Formats

Kim, Do Heui, Kwak, Ja Hun, Szanyi, Janos, Burton, Sarah D, and Peden, Charles HF. Water-induced Bulk Ba(NO3)2 Formation From NO2 Exposed Thermally Aged BaO/Al2O3. United States: N. p., 2007. Web. doi:10.1016/j.apcatb.2006.10.024.
Kim, Do Heui, Kwak, Ja Hun, Szanyi, Janos, Burton, Sarah D, & Peden, Charles HF. Water-induced Bulk Ba(NO3)2 Formation From NO2 Exposed Thermally Aged BaO/Al2O3. United States. doi:10.1016/j.apcatb.2006.10.024.
Kim, Do Heui, Kwak, Ja Hun, Szanyi, Janos, Burton, Sarah D, and Peden, Charles HF. Fri . "Water-induced Bulk Ba(NO3)2 Formation From NO2 Exposed Thermally Aged BaO/Al2O3". United States. doi:10.1016/j.apcatb.2006.10.024.
@article{osti_908943,
title = {Water-induced Bulk Ba(NO3)2 Formation From NO2 Exposed Thermally Aged BaO/Al2O3},
author = {Kim, Do Heui and Kwak, Ja Hun and Szanyi, Janos and Burton, Sarah D and Peden, Charles HF},
abstractNote = {Phase changes in high temperature treated (> 900 °C) 8 or 20 wt% BaO supported on Al2O3 model lean NOx trap (LNT) catalysts, induced by NO2 and/or H2O adsorption, were investigated with powder X-ray Diffraction (XRD), solid state 27Al Magic Angle Spinning Nuclear Magnetic Resonance (MAS NMR) spectroscopy, and NO2 Temperature Programmed Desorption (TPD) experiments. After calcination in dry air at 1000 °C, the XRD and solid state 27Al MAS NMR results confirm that stable surface BaO and bulk BaAl2O4 phases are formed for 8 and 20 wt% BaO/Al2O3, respectively. Following NO2 adsorption over these thermally treated samples, no additional phase changes are observed based on XRD results. However, when water was added to the thermally aged samples after NO2 exposure, the formation of crystalline Ba(NO3)2 particles was observed in both samples. Solid state 27Al MAS NMR is shown to be a good technique for identifying the various Al species present in the materials during the processes studied here. NO2 TPD results demonstrate a significant loss of uptake for the 20 wt% model catalysts upon thermal treatment. However, the described phase transformations upon subsequent water treatment gave rise to the partial recovery of NOx uptake, demonstrating that such a water treatment of thermally aged catalysts can provide a potential method to regenerate LNT materials.},
doi = {10.1016/j.apcatb.2006.10.024},
journal = {Applied Catalysis. B, Environmental},
number = 3-4,
volume = 72,
place = {United States},
year = {Fri Mar 30 00:00:00 EDT 2007},
month = {Fri Mar 30 00:00:00 EDT 2007}
}