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Comparative theoretical study of Au<inf>1-3</inf> and Cu<inf>1-3</inf> clusters supported on SAPO-11 and their interactions with CO

Abstract:

Quantum chemistry calculations were carried out using the ONIOM2 methodology at two different levels of calculation, B3LYP for the high level and UFF for the low level. These calculations were performed on aggregates to analyze the geometries of small clusters of Au1-3 and Cu1-3 supported on SAPO-11. Similarly CO-Au1-3/SAPO-11 and CO-Cu1-3/SAPO-11 moieties obtained by their interaction with CO, were calculated and the results of both cases are compared. The formation energy ΔEF of the metal aggregates and with CO adsorption, C-O and M-CO bond distances and calculated CO stretching frequencies are reported.The most stable structures of the aggregates of Au1-3 and Cu1-3/SAPO-11 are similar, Au3 exhibits acute triangle geometry and Cu3 shows isosceles triangle with a large side geometry. The CO ΔEads values reveal that the CO adsorption is more stable in Au1-3/SAPO-11 than in Cu1-3/SAPO-11. Au-CO distances are larger than Cu-CO.