Density functional study of multiple H2 adsorption and activation on a Pd6 cluster

Deactivation behavior of Pd/C and Pt/C catalysts in the gas-phase hydrodechlorination of chloromethanes: Structure–reactivity relationship

“…Firstly, regarding the computational analysis of independent metal species, we observed that a zero-valent Pt triplet structure, 0 6 Pt , was significantly more stable than that presenting the singlet state, as was also found [43] for the 0 6 Pd cluster (Table 2). Both singlet and triplet 0 6 Pt structures present similar bond-distances and symmetry and negligible dipole moments, indicating spherical charge distribution for the simulated catalytic particles of Pt, as was found for Pd species [41].…”

“…The chemically inert core orbitals of palladium and platinum clusters were described with the effective core potentials of Hay and Wadt [40], which include relativistic effects on valence electrons, while the external orbitals were represented with a double-ζ basis set using Dunning/Huzinaga full double-ζ basis set (Lanl2DZ), which was also used for the rest of the atoms of the species involved in this study. Thus, all the simulations were conducted at the B3LYP/Lanl2DZ computational level, which has been proved to be reliable for systems involving Pd atoms [41,42,43,44,45,46]. Full geometry optimization was done for isolated reactants, Pd and Pt clusters and reactants-metal systems.…”

DFT study on the adsorption and dissociation of H2 on Pdn (n=4, 6, 13, 19, 55) clusters

“…2). In [20] and Pd 6 [23]). They are similar to the dissociation barriers on Pd(1 1 1) and Pd(1 0 0) surfaces [18].…”

“…The H 2 adsorption and dissociation on a series of free small Pd clusters was investigated [20][21][22][23][24][25][26]. DFT calculations showed that the H 2 activation occurs on the Pd n (n = 3, 4) clusters at top site while the H 2 is favorably adsorbed on the Pd 2 cluster at edge site [20,21].…”

“…More recently, the study reported that the H 2 adsorption and dissociation on the Pd 5 clusters and two H adsorbed on cap sites of the nonadjacent faces of the trigonal bipyramidal (tbp) Pd 5 cluster are the most stable [22]. For the H 2 dissociation on the octahedral Pd 6 cluster in triplet state, DFT calculations showed that the energy barrier 0.47 eV is needed to form the intermediate, which is one H bound to the single Pd atom and the second H bridging the Pd-Pd edge [23]. However, the H 2 dissociative chemisorption with energy barrier of 0.13 eV was obtained on octahedral Pd 6 cluster and the sequential H 2 chemisorption on icosahedral Pd 13 clusters revealed that the H 2 dissociation is nearly barrierless [24,25].…”