Alumina-Supported Silver Catalyst for O3-Assisted Catalytic Abatement of CO: Effect of Ag Loading

A series of Ag/Al2O3 catalysts with different Ag loading in a range of 0.5-10 wt% was synthesized by incipient wetness impregnation. The obtained catalysts were characterized by XRD, SEM-EDX, TEM and UV-Visible spectroscopy. It was shown that at low Ag loading (0.5 and 1 wt% Ag) an isolated Ag+ species predominate on the alumina surface. The formation of Ag-n clusters begins as Ag content was increased to 3 wt% Ag. Higher Ag loading (10 wt%) causes an agglomeration of Ag-n clusters and formation of relatively large Ag nanoparticles (Ag-NPs). The catalytic performance of the Ag/Al2O3 catalysts was studied in the conventional (with O-2) and O-3-assisted catalytic CO oxidation (with O-3) and O-3 decomposition reactions within the temperature range of 25-350 degrees C. Analysis of the data obtained allows concluding that conventional CO oxidation proceeds mainly over Ag-n clusters, while for O-3-assited CO oxidation Ag+ species are also necessary. The Ag+ species promote the ozone decomposition and, as a consequence, the formation of highly reactive atomic oxygen species, which are favorable for low-temperature CO activation. The contribution of large metal species (large Ag-n clusters and Ag-NPs) to the overall catalytic performance appears to be less pronounced.

Automated summary

A series of Ag/Al2O3 catalysts with different Ag loading were synthesized and characterized. It was found that the catalysts exhibited different structures and morphologies depending on the Ag loading. The catalytic performance of the catalysts in CO oxidation reactions was investigated, and it was observed that conventional CO oxidation mainly occurred on Ag-n clusters, while O-3-assited CO oxidation required the presence of Ag+ species.