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Mechanisms behind sulfur promoted oxidation of methane

Djamela Bounechada (Institutionen för kemi- och bioteknik, Teknisk ytkemi ; Kompetenscentrum katalys (KCK)) ; Sheedeh Fouladvand (Institutionen för kemi- och bioteknik, Teknisk ytkemi ; Kompetenscentrum katalys (KCK)) ; Torben Pingel (Kompetenscentrum katalys (KCK) ; Institutionen för teknisk fysik, Eva Olsson Group ) ; Lisa Kylhammar (Institutionen för kemi- och bioteknik, Teknisk ytkemi ; Kompetenscentrum katalys (KCK)) ; Eva Olsson (Institutionen för teknisk fysik, Eva Olsson Group ; Kompetenscentrum katalys (KCK)) ; Magnus Skoglundh (Institutionen för kemi- och bioteknik, Teknisk ytkemi ; Kompetenscentrum katalys (KCK)) ; Johan Gustafsson ; Marco Di Michiel ; Mark Newton ; Per-Anders Carlsson (Kompetenscentrum katalys (KCK) ; Institutionen för kemi- och bioteknik, Teknisk ytkemi)
Physical Chemistry Chemical Physics - PCCP (1463-9076). Vol. 15 (2013), 22, p. 8648-8661.
[Artikel, refereegranskad vetenskaplig]

The promoting effect of SO2 on the activity for methane oxidation over platinum supported on silica, alumina and ceria has been studied by flow-reactor, in situ infrared spectroscopy and in situ high-energy x-ray diffraction experiments under transient reaction conditions. The catalytic activity is clearly dependent on the support material and its interaction with the noble metal both in absence and presence of sulfur. On platinum, the competitive reactant adsorption favors oxygen dissociation such that oxygen self-poisoning is observed for Pt/silica and Pt/alumina. Contrarily for Pt/ceria, no oxygen self-poisoning is observed, which seems to be due to additional reaction channels via sites on the platinum-ceria boundary and/or ceria surface considerably far from the Pt crystallites. Addition of sulfur dioxide generally leads to the formation of ad-SOx species on the supports with a concomitant removal and/or blockage/rearrangement of surface hydroxyl groups. Thereby, the methane oxidation is inhibited for Pt/silica, enhanced for Pt/alumina and temporary enhanced followed by inhibition after long-term exposure to sulfur for Pt/ceria. The observations can be explained by competitive oxidation of SO2 and CH4 on Pt/silica, formation of new active sites at the noble metal-support interface promoting dissociative adsorption of methane on Pt/alumina, and in the case of Pt/ceria, formation of promoting interfacial surface sulfates followed by formation of deactivating bulk-like sulfate species. Furthermore, it can be excluded that reduction of detrimental high oxygen coverage and/or oxide formation on the platinum particles through SO2 oxidation is the main cause for the promotional effects observed.



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Denna post skapades 2013-02-12. Senast ändrad 2014-11-27.
CPL Pubid: 173402

 

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Institutioner (Chalmers)

Institutionen för kemi- och bioteknik, Teknisk ytkemi (2005-2014)
Kompetenscentrum katalys (KCK)
Institutionen för teknisk fysik, Eva Olsson Group (2012-2015)

Ämnesområden

Energi
Materialvetenskap
Nanovetenskap och nanoteknik
Transport
Hållbar utveckling
Spektroskopi
Katalys

Chalmers infrastruktur

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Promoting methane oxidation: Effect of catalyst composition and transient operation