In-situ characterization by Near-Ambient Pressure XPS of the catalytically active phase of Pt/Al2O3 during NO and CO oxidation

- Successful application of NAP-XPS to industrial grade catalysts used in heavy duty vehicle exhaust aftertreatment.
- In-situ characterization of the catalytically active phase of Pt/Al2O3.
- Increased oxidation of Pt can be observed under an NO/O2 atmosphere.
- In-situ observed changes in Pt particle oxidation state are interesting in light of previous studies, which have observed activity decrease after exposure to NO/O2.

This study concerns near ambient pressure X-ray photoelectron spectroscopy (NAP-XPS) studies of a Pt/Al2O3 diesel oxidation catalyst used in exhaust aftertreatment. We apply the technique to an industrial-grade porous catalyst, thus bridging both the pressure and materials gap, and probe the shift in binding energy of Pt 4d under different atmospheres. We observe that oxidizing atmospheres induce a shift in binding energy, corresponding to changes in Pt oxidation state, especially pronounced under an atmosphere of NO and O2. Such changes in Pt oxidation state have previously been linked to dynamic changes in NO oxidation activity.

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