Motivated by the suggestion that mainly geometric arguments can explain the obsd. structure sensitivity in the cyclotrimerization of acetylene to benzene on palladium single crystals and on supported palladium particles, this reaction was studied on size-selected Pdn clusters (1≤n≤30) supported on thin MgO(100) films by thermal desorption spectroscopy. Already on small Pdn (1≤n≤6), benzene is readily produced, mainly at low temp. (300 K). For larger clusters (7≤n≤30) benzene also desorbs at a temp. of 430 K, indicating that a crit. ensemble of seven atoms is necessary for high-temp. cyclotrimerization. Using d. functional theory, we attribute this high-temp. desorption of benzene to the presence of three-dimensional clusters. [on SciFinder(R)]     «

Motivated by the suggestion that mainly geometric arguments can explain the obsd. structure sensitivity in the cyclotrimerization of acetylene to benzene on palladium single crystals and on supported palladium particles, this reaction was studied on size-selected Pdn clusters (1≤n≤30) supported on thin MgO(100) films by thermal desorption spectroscopy. Already on small Pdn (1≤n≤6), benzene is readily produced, mainly at low temp. (300 K). For larger clusters (7≤n≤30) benzene also des...     »

Cyclotrimerization catalysts (cyclotrimerization of acetylene to benzene size-effects in the acetylene cyclotrimerization on supported size-selected Pdn clusters (1≤n≤30)) Density functional theory (high-temp. desorption of benzene attributed to the presence of 3-dimensional clusters using DFT size-effects in the acetylene cyclotrimerization on supported size-selected Pdn clusters (1≤n≤30)) Catalyst supports (magnesium oxide size-effects in the acetylene cyclotrimerization on supported size-selected Pdn clusters (1≤n≤30)) Clusters Role: CAT (Catalyst use), USES (Uses) (metal, palladium clusters size-effects in the acetylene cyclotrimerization on supported size-selected Pdn clusters (1≤n≤30)) Adsorbed substances Chemisorption Cluster structure Quantum size effect (size-effects in the acetylene cyclotrimerization on supported size-selected Pdn clusters (1≤n≤30)) Alkynes Role: PEP (Physical, engineering or chemical process), RCT (Reactant), PROC (Process), RACT (Reactant or reagent) (size-effects in the acetylene cyclotrimerization on supported size-selected Pdn clusters (1≤n≤30)) Desorption (thermal, high-temp. desorption of benzene size-effects in the acetylene cyclotrimerization on supported size-selected Pdn clusters (1≤n≤30)) acetylene cyclotrimerization catalyst palladium cluster magnesium oxide thermal desorption     «

Cyclotrimerization catalysts (cyclotrimerization of acetylene to benzene size-effects in the acetylene cyclotrimerization on supported size-selected Pdn clusters (1≤n≤30)) Density functional theory (high-temp. desorption of benzene attributed to the presence of 3-dimensional clusters using DFT size-effects in the acetylene cyclotrimerization on supported size-selected Pdn clusters (1≤n≤30)) Catalyst supports (magnesium oxide size-effects in the acetylene cyclotrimerization on supported s...     »

CAN 133:134927 22-5 Physical Organic Chemistry Institut de Physique de la Matiere Condensee, Universite de Lausanne, Lausanne, Switz. Journal 0039-6028 1309-48-4 (Magnesium oxide) Role: CAT (Catalyst use), USES (Uses) (catalyst support; size-effects in the acetylene cyclotrimerization on supported size-selected Pdn clusters (1≤n≤30)); 66554-19-6 (Palladium, mol.(Pd6)) Role: CAT (Catalyst use), USES (Uses) (octahedral Pd6; size-effects in the acetylene cyclotrimerization on supported size-selected Pdn clusters (1≤n≤30)); 7440-05-3 (Palladium); 150385-94-7 (Palladium, mol. (Pd7)); 150385-95-8 (Palladium, mol. (Pd8)); 266317-62-8 (Palladium, mol. (Pd30)) Role: CAT (Catalyst use), USES (Uses) (size-effects in the acetylene cyclotrimerization on supported size-selected Pdn clusters (1≤n≤30)); 74-86-2 (Acetylene) Role: PEP (Physical, engineering or chemical process), RCT (Reactant), PROC (Process), RACT (Reactant or reagent) (size-effects in the acetylene cyclotrimerization on supported size-selected Pdn clusters (1≤n≤30)); 71-43-2P (Benzene) Role: PEP (Physical, engineering or chemical process), SPN (Synthetic preparation), PREP (Preparation), PROC (Process) (size-effects in the acetylene cyclotrimerization on supported size-selected Pdn clusters (1≤n≤30))     «

CAN 133:134927 22-5 Physical Organic Chemistry Institut de Physique de la Matiere Condensee, Universite de Lausanne, Lausanne, Switz. Journal 0039-6028 1309-48-4 (Magnesium oxide) Role: CAT (Catalyst use), USES (Uses) (catalyst support; size-effects in the acetylene cyclotrimerization on supported size-selected Pdn clusters (1≤n≤30)); 66554-19-6 (Palladium, mol.(Pd6)) Role: CAT (Catalyst use), USES (Uses) (octahedral Pd6; size-effects in the acetylene cyclotrimerization on supported size-...     »