The catalytic activity of supported platinum:: A theoretical study of the activation of H 2

Abstract

Theoretical calculations, which resemble the supported catalyst, were done for different geometric approaches and electronic states of a platinum dimer interacting with a hydrogen molecule. The Pt 2+H 2 reaction curves have been analyzed and compared with previous platinum monomer plus hydrogen molecule reaction using very carefully theoretical ab-initio methods, including relativistic effective core potential in a multi configuration self consistent field (MC-SCF) and a multi reference configuration interaction (MR-CI) variational and perturbative. From the different H 2 to Pt 2 approaches considered, the parallel one is the most interesting: the A 1 symmetry singlet and triplet states of the system lead to dissociatively capture of H 2. These captures present deep wells, 47 and 30 kcal/mol, respectively, and important activation barriers, 18 and 14 kcal/mol. As a consequence of that, they do not allow easy exit channels; but in the minima of the wells, the Pt–H bond is weak, allowing the hydrogen to participate in catalytic reactions.