TY - JOUR
T1 - Effect of reductive treatments on Pt behavior and NOx storage in lean NOx trap catalysts
AU - Wang, Xian Qin
AU - Kim, Do Heui
AU - Kwak, Ja Hun
AU - Wang, Chongmin
AU - Szanyi, Janos
AU - Peden, Charles H.F.
N1 - Funding Information:
Financial support was provided by the U.S. Department of Energy (DOE), Office of Freedom Car and Vehicle Technologies . We also acknowledge valuable discussions with our colleagues at Cummins, Inc. and Johnson Matthey Catalysts. The work was performed in the Environmental Molecular Sciences Laboratory (EMSL) at Pacific Northwest National Laboratory (PNNL). The EMSL is a national scientific user facility and supported by the U.S. Department of Energy (DOE), Office of Biological and Environmental Research. PNNL is a multi-program national laboratory operated for the U.S. DOE by Battelle Memorial Institute under Contract DE-AC06-76RLO 1830.
PY - 2011/10/25
Y1 - 2011/10/25
N2 - 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 NO 2 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 °C 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.
AB - 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 NO 2 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 °C 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.
KW - Ba migration
KW - Reducing temperatures
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U2 - 10.1016/j.cattod.2011.03.032
DO - 10.1016/j.cattod.2011.03.032
M3 - Article
AN - SCOPUS:80054865610
SN - 0920-5861
VL - 175
SP - 78
EP - 82
JO - Catalysis Today
JF - Catalysis Today
IS - 1
ER -