The effect of Al-doping on ZnO nanoparticles applied as catalyst support

Malte Behrens, Giulio Lolli, Nelli Muratova, Igor Kasatkin, Michael Hävecker, Raoul Naumann d’Alnoncourt, Oksana Storcheva, Klaus Köhler, Martin Muhler, Robert Schlögl

Research output: Contribution to journalArticlepeer-review

65 Scopus citations

Abstract

A pure ZnO sample and a sample containing 3 mol% Al were prepared by (co)-precipitation as model materials for the oxidic support phase in Cu/ZnO/Al2O3 methanol synthesis catalysts. The samples were characterized with respect to their crystal, defect and micro-structure using various methods (XRD, TEM, XPS, UV-vis spectroscopy, EPR, NMR). It was found that a significant fraction of the Al is incorporated into the ZnO lattice and enhances the defect chemistry of the material. The defect structure, however, was not stable under reducing conditions as applied in catalytic reactions. Al ions migrated towards the surface of the ZnO nanoparticles leading to formation of an Al-rich shell and an Al-depleted core. This process proceeds during the first 10-20 hours on stream and is associated with strong modification of the optical bandgap energy and the EPR signal of donor sites present in ZnO.

Original languageEnglish
Pages (from-to)1374-1381
Number of pages8
JournalPhysical Chemistry Chemical Physics
Volume15
Issue number5
DOIs
StatePublished - 2 Jan 2013

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