Mechanisms behind sulfur promoted oxidation of methane
Artikel i vetenskaplig tidskrift, 2013

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.

Författare

Djamela Bounechada

Kompetenscentrum katalys (KCK)

Chalmers, Kemi- och bioteknik, Teknisk ytkemi

Sheedeh Fouladvand

Kompetenscentrum katalys (KCK)

Chalmers, Kemi- och bioteknik, Teknisk ytkemi

Torben Nilsson Pingel

Chalmers, Teknisk fysik, Eva Olsson Group

Kompetenscentrum katalys (KCK)

Lisa Kylhammar

Chalmers, Kemi- och bioteknik, Teknisk ytkemi

Kompetenscentrum katalys (KCK)

Eva Olsson

Chalmers, Teknisk fysik, Eva Olsson Group

Kompetenscentrum katalys (KCK)

Magnus Skoglundh

Chalmers, Kemi- och bioteknik, Teknisk ytkemi

Kompetenscentrum katalys (KCK)

Johan Gustafsson

Marco Di Michiel

Mark Newton

Per-Anders Carlsson

Kompetenscentrum katalys (KCK)

Chalmers, Kemi- och bioteknik, Teknisk ytkemi

Physical Chemistry Chemical Physics

1463-9076 (ISSN) 1463-9084 (eISSN)

Vol. 15 22 8648-8661

Drivkrafter

Hållbar utveckling

Styrkeområden

Nanovetenskap och nanoteknik

Transport

Energi

Materialvetenskap

Ämneskategorier

Fysikalisk kemi

Kemiska processer

Fundament

Grundläggande vetenskaper

DOI

10.1039/c3cp44289f