Platinum oxidation and sulphur deactivation in NOx storage catalysts
Journal article, 2004

Flow reactor experiments and X-ray photoelectron spectroscopy (XPS) measurements were used to investigate the importance of platinum oxide formation on Pt/BaO/Al2O3 NOx storage catalysts during reactions conditions. The reaction studied was NO(g) + 1/2 O-2(g) <----> NO2 (g). During NO2 exposure of the catalyst the NO2 dissociation rate decreased during the reaction. This activity decrease with time was also studied with XPS and it was found to be due to platinum oxide formation. The influence of sulphur exposure conditions on the performance of the NOx storage catalysts was studied by exposing the samples to lean and/or rich gas mixtures, simulating the conditions in a mixed lean application, containing SO2 The main results show that all samples are sensitive to sulphur and that the deactivation proceeds faster when SO2 is present in the feed under rich conditions than under lean or continuous SO2 exposure. Additionally, the influence of the noble metals present in the catalysts was investigated regarding sulphur sensitivity and it was found that a combination of platinum and rhodium seems to be preferable to retain high performance of the catalyst under SO2 exposure and subsequent regeneration. Finally, the behaviour of micro-fabricated model NOx storage catalysts was studied as a function of temperature and gas composition with area-resolved XPS. These model catalysts consisted of a thin film of Pt deposited on one-half of a BaCO3 pellet. It was found that the combination of SO2 and O-2 resulted in migration of Pt on the BaCO3 support up to one mm away from the Pt/BaCO3 interface.

XPS

sulphur deactivation

storage

NO

platinum oxide

nitrogen oxides

Author

Erik Fridell

Competence Centre for Catalysis (KCK)

Chalmers, Applied Physics, Chemical Physics

Annika Amberntsson

Chalmers, Applied Physics

Competence Centre for Catalysis (KCK)

Louise Olsson

Chalmers, Department of Chemical Engineering and Environmental Sciences, Chemical Reaction Engineering

Competence Centre for Catalysis (KCK)

Ann W. Grant

Chalmers, Applied Physics, Chemical Physics

Magnus Skoglundh

Chalmers, Department of Materials and Surface Chemistry, Applied Surface Chemistry

Competence Centre for Catalysis (KCK)

Topics in Catalysis

1022-5528 (ISSN) 1572-9028 (eISSN)

Vol. 30-31 1-4 143-146

Driving Forces

Sustainable development

Areas of Advance

Nanoscience and Nanotechnology (2010-2017)

Transport

Energy

Materials Science

Subject Categories

Physical Sciences

Chemical Engineering

More information

Created

10/7/2017