THE CATALYTIC ACTIVITY OF SUPPORTED PLATINUM - A THEORETICAL-STUDY OFTHE ACTIVATION OF H-2

Theoretical calculations, which resemble the supported catalyst, were done for different geometric approaches and electronic states of a pla tinum dimer interacting with a hydrogen molecule. The Pt-2 + H-2 react ion curves have been analyzed and compared with previous platinum mono mer plus hydrogen molecule reaction using very carefully theoretical a b-initio methods, including relativistic effective core potential in a multi configuration self consistent field (MC-SCF) and a multi refere nce configuration interaction (MR-CI) variational and perturbative. Fr om the different H-2 to Pt-2 approaches considered, the parallel one i s the most interesting: the A(1) symmetry singlet and triplet states o f the system lead to dissociatively capture of H-2. These captures pre sent deep wells, 47 and 30 kcal/mol, respectively, and important activ ation 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 react ions.