RT Journal Article
SR Electronic
T1 Mixed-Phase Oxide Catalyst Based on Mn-Mullite (Sm, Gd)Mn<sub>2</sub>O<sub>5</sub> for NO Oxidation in Diesel Exhaust
JF Science
JO Science
FD American Association for the Advancement of Science
SP 832
OP 835
DO 10.1126/science.1225091
VO 337
IS 6096
A1 Wang, Weichao
A1 McCool, Geoffrey
A1 Kapur, Neeti
A1 Yuan, Guang
A1 Shan, Bin
A1 Nguyen, Matt
A1 Graham, Uschi M.
A1 Davis, Burtron H.
A1 Jacobs, Gary
A1 Cho, Kyeongjae
A1 Hao, Xianghong (Kelly)
YR 2012
UL http://science.sciencemag.org/content/337/6096/832.abstract
AB Oxidation of nitric oxide (NO) for subsequent efficient reduction in selective catalytic reduction or lean NOx trap devices continues to be a challenge in diesel engines because of the low efficiency and high cost of the currently used platinum (Pt)–based catalysts. We show that mixed-phase oxide materials based on Mn-mullite (Sm, Gd)Mn2O5 are an efficient substitute for the current commercial Pt-based catalysts. Under laboratory-simulated diesel exhaust conditions, this mixed-phase oxide material was superior to Pt in terms of cost, thermal durability, and catalytic activity for NO oxidation. This oxide material is active at temperatures as low as 120°C with conversion maxima of ~45% higher than that achieved with Pt. Density functional theory and diffuse reflectance infrared Fourier transform spectroscopy provide insights into the NO-to-NO2 reaction mechanism on catalytically active Mn-Mn sites via the intermediate nitrate species.