Probing the Oxidation/Reduction Dynamics of Fresh and P-, Na-, and K-Contaminated Pt/Pd/Al2O3 Diesel Oxidation Catalysts by STEM, TPR, and in Situ XANES

• This study examines the oxidation and reduction behavior of Pt/Pd/Al2O3 diesel oxidation catalysts at temperatures and gas compositions that model the conditions of the working diesel oxidation catalyst in a truck exhaust system. In situ measurements using Pt L3 X-ray edge absorption spectroscopy are coupled with temperature-programmed reduction (TPR) and scanning transmission electron microscopy measurements to characterize the catalyst. The fresh catalyst is compared with chemically aged catalysts, exposed to Na, K, and P contaminants. Phosphorus exhibits strong, spatially localized interactions with the Pt/Pd catalyst nanoparticles that are reflected in a strong shift to lower energy of the Pt L3 edge under CO oxidation conditions. The Na and K poisons are spread more uniformly throughout the catalyst washcoat and do not strongly affect the edge spectra or the TPR-determined catalyst reducibility.

Ämnesord

TEKNIK OCH TEKNOLOGIER  -- Kemiteknik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Chemical Engineering (hsv//eng)

NATURVETENSKAP  -- Kemi -- Fysikalisk kemi (hsv//swe)

NATURAL SCIENCES  -- Chemical Sciences -- Physical Chemistry (hsv//eng)

Nyckelord

Redox reactions

Platinum

Nanoparticles

Catalysts

Oxidation

Chemical Engineering

Kemiteknik

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