Density functional theory (DFT) studies of C-1 and C-2 hydrocarbons species on Pt clusters

Quantum chemical calculations were performed using density functional theor y to study interactions of C-1 and C-2 hydrocarbons with 10-atom Pt cluster s. The heats of ethylene adsorption to form di-sigma- and pi-adsorbed speci es were calculated to be -171 kJ/mol and -103 kJ/mol, respectively, at 298 K. The calculated heat is -109 kJ/mol for the formation of ethylidyne speci es from ethylene adsorption, with the formation of gas phase dihydrogen at 298 K. The heat of adsorption of acetylene to form molecular di-sigma/pi-ad sorbed species is -209 kJ/mol, and the heat of formation of di-sigma/pi vin ylidene species is -278 kJ/mol at 298 K. The calculated structural paramete rs of these species agree with the available experimental data. The same 10 -atom platinum cluster is used to calculate the heats of adsorption of vari ous other hydrocarbon species which may be reactive intermediates for hydro carbon conversion reactions. These species include vinyl, methyl, ethyl, me thylene, ethylidene, and ethylylidene species. (C) 1998 Academic Press.