Oscillatory CO Oxidation Over Pt/Al2O3 Catalysts Studied by In situ XAS and DRIFTS
- 898 Downloads
Fresh and mildly aged Pt/Al2O3 model diesel oxidation catalysts with small and large noble metal particle size have been studied during CO oxidation under lean burn reaction conditions to gain more insight into the structure and oscillatory reaction behaviour. The catalytic performance, CO adsorption characteristics using in situ DRIFTS and oxidation state using in situ XAS were correlated. Stable and pronounced oscillations only occurred over the catalyst with smaller particle sizes. Characteristic for this catalyst are low-coordinated surface Pt sites (more corner and edge atoms) which seem to become oxidized at elevated temperature as evidenced by in situ DRIFTS and in situ XAS. In situ XAS further uncovered that the oxidation of the Pt surface starts from the end of the catalyst bed and the oxidation state oscillates like the catalytic activity.
KeywordsPlatinum CO oxidation Oscillations In situ DRIFTS In situ XAS Spatially resolved studies
The authors wish to thank Di Wang (Institute for Nanotechnology, KIT) for TEM work and the group of Peter Pfeifer (Institute for Micro Process Engineering, KIT) for carrying out hydrogen chemisorption measurements. Gian Luca Chiarello is acknowledged for help and in-house modifications of the DRIFTS instrument. Finally we thank KIT, the BMBF Project “Materials in Action (MatAkt, 05K10VKB)” for financial support and SLS (Villigen, Switzerland) and ANKA (Karlsruhe, Germany) for providing beamtime. Maarten Nachtegaal and Olga Safonova (SLS) and Stefan Mangold (ANKA) are acknowledged for support during the XAS experiments.
- 10.Salomons S, Hayes RE, Votsmeier M, Drochner A, Vogel H, Malmberg S, Gieshoff J (2007) Appl Catal B 70(1–4):305–313Google Scholar
- 17.Yang J, Tschamber V, Habermacher D, Garin F, Gilot P (2008) Appl Catal B 83(3–4):229–239Google Scholar
- 22.D’Netto GA, Brown JR, Schmitz RA (1984) Chem React Eng 87:247–254Google Scholar
- 27.Gracia FJ, Wolf EE (2004) Chem Eng Sci 59(22–23):4723–4729Google Scholar
- 30.Sheppard N, Nguyen TT (1987) The vibrational spectra of carbon monoxide chemisorbed in the surfaces of metal catalysts: a suggested scheme of interpretation. In: Clark RGH, Hester RE (eds) Advances in infrared and Raman spectroscopy, vol 5. Heyden, London, pp 67–148Google Scholar
- 36.Deutschmann O (ed) (2012) Modeling and simulation of heterogeneous catalytic reactions: from the molecular process to the technical system. Wiley, WeinheimGoogle Scholar