Metal-Support Interaction – a Key Reason for Ag Catalyst Activity in Low-Temperature Oxidation
The metal-support interaction in supported catalysts is very important for understanding of both nature of catalytic action and mechanisms of oxidative reactions. The aim of the present work is to reveal the role of ultrasmall silver particles – oxide support interaction in low-temperature oxidation. The Ag-“inert” support (Ag/SiO2 catalysts) and Ag-“active” support (Ag/CeO2 catalysts) interfaces were studied in details. It was shown that weak interaction of ultrasmall silver particles with both “inert” (silica) and “active” (ceria) supports is a compulsory condition for high activity in low-temperature CO oxidation. In Ag/CeO2/SiO2 catalysts the oxidation of CO even at temperatures below 0 oC takes place only in the presence of Ag-SiO2 interaction, while the enhanced Ag-CeO2 interface is a reason for elevated activity in deep oxidation of formaldehyde and dehydrogenation of ethanol to acetaldehyde.