Theoretical study of small clusters Au_(3-4) on Au/SAPO-11 catalysts and their interactions with CO

摘要

Quantum chemistry calculations were done, 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 Au_3/SAPO-11, Au_4/SAPO-11, CO-AU_3/SAPO-11 and CO-AU_4/SAPO-11 aggregates to analyze the geometries of small clusters of Au_3 and Au_4 on SAPO-11 support. Au_3 cluster present a triangle structure in Au_3/SAPO-11. Au_4 cluster shows a "Y shaped" structure in Au_4/SAPO-11. Au_4 as a rhombus structure is also studied but it is an unstable intermediate to the "Y shaped" structure. The CO interaction with Au_3 and Au_4/SAPO-11 is studied, this CO adsorption is different from reported in the literature. The formation energy AEf of the aggregates and the CO adsorption energy ΔE_(ads) on them are presented.