Effects of Ba loading and calcination temperature on BaAl2O4 formation for BaO/Al2O3 NOx Storage and Reduction Catalysts

Journal Article · Sun Apr 30 04:00:00 EDT 2006 · Catalysis Today, 114(1):86-93

DOI:https://doi.org/10.1016/j.cattod.2006.02.016· OSTI ID:882380

Szailer, Tamas; Kwak, Ja Hun; Kim, Do Heui; Szanyi, Janos; Wang, Chong M; Peden, Charles HF

The effect of thermal treatment on the structure and chemical properties of Ba-oxide-based NOx storage/reduction catalysts with different Ba loadings was investigated using BET, TEM, EDS, TPD and FTIR techniques. On the basis of the present and previously reported results, we propose that moderate (< ~873 K) temperature calcinations result in a single monolayer (ML) ‘coating’ of BaO on the alumina surface. At high Ba loading in excess of that required for a full monolayer ‘coating’ (> 8 wt.% BaO), small (~5 nm) particles of ‘bulk’ BaO are present on top of the 1 ML BaO/Al2O3 surface. We did not observe any detectable morphological changes upon higher temperature thermal treatment of 2 and 8 wt% BaO/Al2O3 samples, while dramatic changes occurred for the 20 wt% sample. In this latter case, the transformations included BaAl2O4 formation at the expense of the bulk BaO phase. In particular, we conclude that the surface (ML) BaO phase is quite stable against thermal treatment, while the bulk phase provides the source of Ba for BaAl2O4 formation.

• Research Organization: Pacific Northwest National Laboratory (PNNL), Richland, WA (US), Environmental Molecular Sciences Laboratory (EMSL)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 882380
• Report Number(s): PNNL-SA-47049; 6694; VT0401000
• Journal Information: Catalysis Today, 114(1):86-93, Journal Name: Catalysis Today, 114(1):86-93 Journal Issue: 1 Vol. 114; ISSN CATTEA; ISSN 0920-5861
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
54 ENVIRONMENTAL SCIENCES
ALUMINIUM OXIDES
BARIUM OXIDES
BaO/Al2O3
CALCINATION
CATALYSTS
CHEMICAL PROPERTIES
Environmental Molecular Sciences Laboratory
HEAT TREATMENTS
LOADING RATE
MICROSTRUCTURE
NITROGEN OXIDES
NOx storage/reduction
PHASE TRANSFORMATIONS
REDUCTION
catalyst morphology.