Catalytic Oxidation of CO over Ordered Mesoporous Platinum
Journal article, 2008

Hexagonal phase mesoporous (H-1-Pt) was recently reported to have different catalytic properties compared to conventional platinum catalysts. To further investigate this observation the catalytic activity of H-1-Pt/Al2O3 for CO oxidation was compared with the activity of a corresponding catalyst prepared from Pt-black (Pt-black/Al2O3). The H-1-Pt/Al2O3 catalyst showed ignition at lower temperatures but extinction at higher temperatures compared to Pt-black/Al2O3. These observations were further supported by oxygen step-response experiments at constant temperature, where the H-1-Pt/Al2O3 catalyst showed ignition at lower oxygen concentrations when starting from a CO poisoned surface and extinction at higher O-2 concentrations when starting from the high-reactive state. Furthermore, adsorption of CO on the catalysts was studied in situ using infrared spectroscopy in absence and presence of oxygen after pre-oxidation and pre-reduction, respectively. At 150 degrees C the H-1-Pt/Al2O3 sample showed activity for CO oxidation in the presence of oxygen regardless of pretreatment, whereas Pt-black/Al2O3 was inactive due to CO self-poisoning. The differences observed in the low reactive state are suggested to be due to structural differences of the platinum surface in the catalysts resulting in a lower sensitivity of the H-1-Pt/Al2O3 catalyst towards CO self-poisoning and a higher capacity to activate oxygen, and thus a higher activity for CO oxidation. During the high reactive state, the observed higher sensitivity to the concentration ratio between CO and oxygen, and to the temperature is likely due to less optimal ratio between the sticking coefficients of the reactants on the H-1-Pt catalyst and to higher mass-transport limitations in its narrower pores during the initial stage of the extinction.

platinum

ignition

CO oxidation

Pt/Al2O3

catalyst

extinction

Author

Ali Saramat

Competence Centre for Catalysis (KCK)

Chalmers, Chemical and Biological Engineering, Applied Surface Chemistry

Peter Thormählen

Competence Centre for Catalysis (KCK)

Chalmers, Applied Physics, Chemical Physics

Magnus Skoglundh

Chalmers, Chemical and Biological Engineering, Applied Surface Chemistry

Competence Centre for Catalysis (KCK)

George Attard

University of Southampton

Anders Palmqvist

Chalmers, Chemical and Biological Engineering, Applied Surface Chemistry

Competence Centre for Catalysis (KCK)

Journal of Catalysis

0021-9517 (ISSN) 1090-2694 (eISSN)

Vol. 253 2 253-260

Driving Forces

Sustainable development

Areas of Advance

Nanoscience and Nanotechnology (2010-2017)

Transport

Energy

Materials Science

Subject Categories

Materials Engineering

Chemical Engineering

Other Environmental Engineering

DOI

10.1016/j.jcat.2007.11.007

More information

Latest update

2/28/2018