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Schlagwörter:
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Zusammenfassung:
In heterogeneous catalysis, a catalytic process takes place at nite temperature and
at nite pressure of the atmosphere of the reactant gases. By applying ab initio atom-
istic thermodynamics to the model case of free Au2 and Au-2 clusters in an atmosphere
of O2 and CO, we derive all the thermodynamically possible reaction paths for the ox-
idation of CO to COV. This analysis lets us explain how gold clusters enable oxidation
reactions without breaking the spin-conservation rule. Furthermore, we identify special
cluster+ligands compositions such as reaction intermediates and poisoned species. In
particular, a thermodynamically driven poisoning is identied for the catalytic system
containing free Au2 , and the experimental (p; T) conditions that avoid its formation
are suggested. This implies that for some systems a catalytic cycle can be established,
on thermodynamics grounds, only in a dened range of temperatures and pressures. In
addition, our predictions for Au-2 provide the so far most complete interpretation of
the available experimental data [Socaciu et al, J. Am. Chem. Soc. 125, 10437 (2003)].
