The acetylene trimerization on the group VIII transition metal atoms, Rh and Pd, as well as on Ag atoms supported on MgO thin films has been studied exptl. and theor. The three metal atoms with the at. configurations 4d85s1 (Rh), 4d10s0 (Pd) and 4d105s1 (Ag) behave distinctly differently. The coinage metal atom silver is basically inert for this reaction, whereas Pd is active at 220 and 320 K, and Rh produces benzene in a rather broad temp. range from 350 to ca. 430 K. The origins of these differences are not only the different electronic configurations, leading to a weak interaction of acetylene with silver due to strong Pauli repulsion with the 5s electron but also the different stability and dynamics of the three atoms on the MgO surface. In particular, Rh and Pd atoms interact differently with surface defects like the oxygen vacancies (F centers) and the step edges. Pd atoms migrate already at low temp. exclusively to F centers where the cyclotrimerization is efficiently promoted. The Rh atoms on the other hand are not only trapped on F centers but also at step edges up to about 300 K. Interestingly, only Rh atoms on F centers catalyze the trimerization reaction whereas they are turned inert on the step edges due to strong steric effects. [on SciFinder(R)]     «

The acetylene trimerization on the group VIII transition metal atoms, Rh and Pd, as well as on Ag atoms supported on MgO thin films has been studied exptl. and theor. The three metal atoms with the at. configurations 4d85s1 (Rh), 4d10s0 (Pd) and 4d105s1 (Ag) behave distinctly differently. The coinage metal atom silver is basically inert for this reaction, whereas Pd is active at 220 and 320 K, and Rh produces benzene in a rather broad temp. range from 350 to ca. 430 K. The origins of these diffe...     »

CAN 142:398241 66-3 Surface Chemistry and Colloids Institute of Surface Chemistry and Catalysis, University of Ulm, Ulm, Germany. Journal 1463-9076 7440-05-3 (Palladium); 7440-16-6 (Rhodium); 7440-22-4 (Silver) Role: CPS (Chemical process), NUU (Other use, unclassified), PEP (Physical, engineering or chemical process), PROC (Process), USES (Uses) (acetylene trimerization on Ag, Pd, and Rh atoms deposited on MgO film); 74-86-2 (Acetylene) Role: CPS (Chemical process), PEP (Physical, engineering or chemical process), PROC (Process) (acetylene trimerization on Ag, Pd, and Rh atoms deposited on MgO film); 1309-48-4 (Magnesium oxide) Role: NUU (Other use, unclassified), USES (Uses) (acetylene trimerization on Ag, Pd, and Rh atoms deposited on MgO film)     «

CAN 142:398241 66-3 Surface Chemistry and Colloids Institute of Surface Chemistry and Catalysis, University of Ulm, Ulm, Germany. Journal 1463-9076 7440-05-3 (Palladium); 7440-16-6 (Rhodium); 7440-22-4 (Silver) Role: CPS (Chemical process), NUU (Other use, unclassified), PEP (Physical, engineering or chemical process), PROC (Process), USES (Uses) (acetylene trimerization on Ag, Pd, and Rh atoms deposited on MgO film); 74-86-2 (Acetylene) Role: CPS (Chemical process), PEP (Physical, engineerin...     »