abstract
Selectivity is a must for new high performance catalysts which are required to fit strict environmental regulations. RuO2 has been proposed as a mild oxidant capable of performing selective oxidations of alcohols to aldehydes and ketones. However, it fails in another appealing partial oxidation, that of ethylene to its epoxide, where complete oxidation occurs. In contrast, both reactions are selective on Ag, a catalyst that shows similar binding energies for the active oxidation species, oxygen. By means of density functional theory applied to slabs we have been able to unravel the origin of the, in principle erratic, selectivity of RuO2 in partial oxidations. The behavior can be understood as being due to a combination of the basicity of O atoms, the relative binding energies of reactants and products to the surface (thermodynamic factor), and the structure sensitivity of some steps in the oxidation process due to difficult O mobility on RuO2.
keywords
ETHYLENE EPOXIDATION; METHANOL DECOMPOSITION; PROPYLENE EPOXIDATION; CARBON-MONOXIDE; DEACON PROCESS; HCL OXIDATION; SURFACE; CATALYSTS; OXIDE; ADSORPTION
subject category
Chemistry; Physics
authors
Lopez, N; Novell-Leruth, G
our authors
Gerard Novell Leruth
Researcheracknowledgements
Financial support comes from the Spanish MICINN (Consolider Ingenio 2010 CSD2006-003, CTQ2009-07553BQU). Extensive calculations were performed at the RES-BSC resources.