Atomically well-defined Au-25(SR)(17/18) nanoclusters deposited on silica supports for the aerobic epoxidation of trans-stilbene
Résumé
Two atomically well-defined thiolate gold nanoclusters, Au-25(SC2H4Ph)(18) and Au-25(SPhNH2)(17), having the same gold core but different thiolate ligands have been deposited on silica supports and the obtained catalysts have been tested in the aerobic oxidation of trans-stilbene. By properly selecting the support to maximize cluster/surface interactions, it was possible to prepare materials with small nanoparticles and very narrow particle size distributions. Au-25(SPhNH2)(17)@SBA-1 5 catalyst showed an activity and a trans-stilbene epoxide selectivity comparable to the best heterogeneous catalysts. Elimination of the thiolate molecules by calcination did not significantly modify the particle size but decreased the activity, pointing out the critical role of the ligands in the reaction. (C) 2014 Elsevier B.V. All rights reserved.