Effect of reductive treatments on Pt behavior and NOx storage in lean NOx trap catalysts

Journal Article · Sat Oct 01 04:00:00 EDT 2011 · Catalysis Today, 175(1):78– 82

DOI:https://doi.org/10.1016/j.cattod.2011.03.032· OSTI ID:1025671

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

Lean NOx trap (LNT) catalysts represent a promising approach to meet increasingly stringent NOx emission regulations on diesel and other lean-burn engines. Pt material properties, including dispersion and particle size, are known to be important factors in determining NOx uptake performance, since Pt provides active sites for NO oxidation to NO2 necessary for storing NOx as nitrates, and for the reduction of nitrates to N2. In this work, the physicochemical properties of Pt in Pt-BaO/Al2O3 LNT catalysts, such as the Pt accessible surface area and particle size, were investigated by using various tools, such as irreversible volumetric H2 chemisorption, high resolution transmission electron microscopy (HRTEM), and X-ray diffraction (XRD), following successive reductive treatments at elevated temperatures. NOx uptake activities were also measured to establish a relationship between the properties of Pt and NOx storage following identical high-temperature reductive treatments. We find that the reductive treatments of Pt-BaO/Al2O3 lean NOx trap catalysts at temperatures up to 500 ºC promote a significant increase in NOx uptake explained, in part, by an induced close interaction between Pt and BaO phases in the catalyst, thus enabling facilitation of the NOx storage process.

• 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: 1025671
• Report Number(s): PNNL-SA-79182; 35404; VT0401000
• Journal Information: Catalysis Today, 175(1):78– 82, Journal Name: Catalysis Today, 175(1):78– 82 Journal Issue: 1 Vol. 175; ISSN CATTEA; ISSN 0920-5861
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
54 ENVIRONMENTAL SCIENCES
Ba migration
CATALYSTS
CHEMISORPTION
ENGINES
Environmental Molecular Sciences Laboratory
Lean NOx traps
NITRATES
OXIDATION
PARTICLE SIZE
PERFORMANCE
REGULATIONS
RESOLUTION
STORAGE
SURFACE AREA
TRANSMISSION ELECTRON MICROSCOPY
X-RAY DIFFRACTION
reducing temperatures