The effect of platinum distribution in monolithic catalysts on the oxidation of CO and hydrocarbons
Artikel i vetenskaplig tidskrift, 2005

Monolithic Pt/gamma-Al2O3 catalysts were prepd. by depositing of the platinum phase, either homogeneously or heterogeneously (i.e., local high platinum concn.), in the washcoat. The influence of the platinum distribution on the ignition and extinction processes for oxidn. of CO, propene, and propane, resp., was investigated by both temp.-programmed and oxygen step-response flow-reactor expts. In addn., in situ XANES spectroscopy was used to follow changes in the chem. state of platinum during propane oxidn. For samples with heterogeneous platinum distribution, the results show an improved low-temp. activity for CO oxidn., whereas no clear improvement is obsd. for oxidn. of propene or propane. Comparison of the results for CO and hydrocarbon oxidn. shows that the improved activity cannot be explained by thermal effects. Moreover, calcns. indicate that the enhanced activity for CO oxidn. can be due to mass-transfer phenomena. This could not be confirmed by our expts., however. Instead, the improved activity for CO oxidn. can be due to varying platinum particle size between the samples. Furthermore, the oxidn. of propane is shown to be highly influenced by the oxygen concn., showing an activity max. for gas compositions close to the stoichiometric. High oxygen levels result most probably in a predominantly oxygen-covered surface, which inhibits the reaction and, as supported by the in situ XANES experiments, passivates the surface by forming platinum oxide.

Platinum

Mass transport

Alumina

Environmental catalysis

Propane

Structure sensitivity

XANES spectroscopy

Total oxidation

Heat transport

CO

Propene

Low-temperature activity

Platinum oxide

Författare

Karl Arnby

Chalmers, Kemi- och bioteknik, Teknisk ytkemi

Kompetenscentrum katalys (KCK)

Johan Assiks

Kompetenscentrum katalys (KCK)

Chalmers, Kemi- och bioteknik, Teknisk ytkemi

Per-Anders Carlsson

Kompetenscentrum katalys (KCK)

Chalmers, Kemi- och bioteknik, Kemisk reaktionsteknik

Anders Palmqvist

Kompetenscentrum katalys (KCK)

Chalmers, Kemi- och bioteknik, Teknisk ytkemi

Magnus Skoglundh

Kompetenscentrum katalys (KCK)

Chalmers, Kemi- och bioteknik, Teknisk ytkemi

Journal of Catalysis

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

Vol. 233 1 176-185

Drivkrafter

Hållbar utveckling

Styrkeområden

Nanovetenskap och nanoteknik

Transport

Energi

Materialvetenskap

Ämneskategorier

Kemiteknik

Miljövetenskap

DOI

10.1016/j.jcat.2005.04.031