Platinum induced crosslinking of polycarbosilanes for the formation of highly porous CeO2/silicon oxycarbide catalysts

Publikation: Beitrag in FachzeitschriftForschungsartikelBeigetragenBegutachtung

Beitragende

  • Emanuel Kockrick - , Technische Universität Dresden (Autor:in)
  • Robert Frind - , Technische Universität Dresden (Autor:in)
  • Marcus Rose - , Technische Universität Dresden (Autor:in)
  • Uwe Petasch - , Fraunhofer-Institut für Keramische Technologien und Systeme (Autor:in)
  • Winfried Böhlmann - , Universität Leipzig (Autor:in)
  • Dorin Geiger - , Technische Universität Dresden (Autor:in)
  • Mathias Herrmann - , Fraunhofer-Institut für Keramische Technologien und Systeme (Autor:in)
  • Stefan Kaskel - , Professur für Anorganische Chemie (I) (AC1) (Autor:in)

Abstract

A new synthesis scheme for the formation of porous CeO2/Pt- polycarbosilane composites using inverse microemulsions is presented. Aqueous hexachloroplatinic acid was used as a hydrosilylation catalyst causing crosslinking of allyl groups in a liquid polycarbosilane (PCS). The resulting polymers are temperature stable and highly porous. The Pt catalyst content and post-treatment of the polymer can be used to adjust the porosity. For the first time hydrophobic polymers with specific surface areas up to 896 m2/g were obtained by catalytic crosslinking of polycarbosilanes. Ceria nanoparticles 2-3 nm in diameter are well dispersed in the PCS matrix as proven using high resolution electron microscopy. Porosity of the hydrophobic materials could be increased up to 992 m2/g by adding divinylbenzene in the oil phase. Pyrolyses at 1200-1500 °C and post-oxidative treatment at various temperatures produce porous ceramic structures with surface areas up to 423 m2/g. X-Ray diffration investigations show that the crystallinity of the SiC matrix can be controlled by the pyrolysis temperature. Post-oxidative treatments cause silicon oxycarbide formation. Structure and morphology of the polymeric and ceramic composites were investigated using 29Si MAS NMR, FESEM, FT-IR and EDX techniques. The temperature programmed oxidation (TPO) of methane shows a high catalytic activity of CeO2/Pt-SiC(O) composites lowering the onset in the TPO to 400-500 °C.

Details

OriginalspracheEnglisch
Seiten (von - bis)1543-1553
Seitenumfang11
FachzeitschriftJournal of materials chemistry
Jahrgang19
Ausgabenummer11
PublikationsstatusVeröffentlicht - 2009
Peer-Review-StatusJa