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Poisoning mechanisms of MgO-supported Au clusters in CO oxidation

Mpourmpakis, G; Stamatakis, M; Nikbin, N; Christiansen, MA; Vlachos, DG; (2012) Poisoning mechanisms of MgO-supported Au clusters in CO oxidation. In:

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Abstract

We investigated the CO oxidation mechanism on MgO-supported, subnanometer Au catalysts (Au6, Au8 and Au10), through multiscale modeling that combines density functional theory calculations with kinetic Monte Carlo simulations. For the case of Au6, our work unravels multiple catalyst deactivation mechanisms that depend on the type of the support vacancies. In defect-poor MgO or in the presence of a Mg-vacancy, O2 interacts weakly with Au6 and poisoning occurs by CO. On Au6 clusters that interact with an O vacancy of the support, O2 can be chemisorbed and some activity is observed. However, eventually, the Au6 cluster is poisoned by carbonate. For the similar case of negatively charged Au8 and Au10 clusters the carbonate formed was shown to decompose through pathways that result in CO2 production. Thus, these three different clusters were shown to exhibit different activity towards the CO oxidation reaction. This study underscores the importance of a cluster's charge state on the catalytic activity and explains several experimental observations regarding the variable activity of metal-oxide supported Au nanoclusters.

Type: Proceedings paper
Title: Poisoning mechanisms of MgO-supported Au clusters in CO oxidation
ISBN-13: 9780816910731
UCL classification: UCL > Provost and Vice Provost Offices
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science > Dept of Chemical Engineering
URI: http://discovery.ucl.ac.uk/id/eprint/1457830
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