High-performance carbon monoxide oxidation catalysts engineered for carbon dioxide lasers.

摘要

The low-temperature CO oxidation activity of numerous materials has been evaluated in order to develop efficient catalysts for use in CO{dollar}sb2{dollar} lasers. The materials were screened for activity in small, stoichiometric concentrations of CO and O{dollar}sb2{dollar} at temperatures near 55{dollar}spcirc{dollar}C. An Au/MnO{dollar}sb{lcub}rm x{rcub}{dollar} catalyst was synthesized which exhibited exceptional CO oxidation activity while maintaining negligible performance decay over a period of at least 70 days. The data suggest that Au/MnO{dollar}sb{lcub}rm x{rcub}{dollar} has potential applications in air purification and CO gas sensing as well.; Extensive surface characterization data from Pt/SnO{dollar}sb{lcub}rm x{rcub}{dollar} and Au/MnO{dollar}sb{lcub}rm x{rcub}{dollar} catalysts are reported which relate surface composition and chemical state information to corresponding CO oxidation activity data. Ion scattering spectroscopy (ISS), Auger electron spectroscopy (AES), angle-resolved Auger electron spectroscopy (ARAES) and X-ray photoelectron spectroscopy (XPS) were utilized to observe the behavior of these surfaces as a function of numerous pretreatments which alter their catalytic activity. The results suggest that Pt(OH){dollar}sb2{dollar} and Pt/Sn alloy formation may play a key role in the CO oxidation mechanism on Pt/SnO{dollar}sb{lcub}rm x{rcub}{dollar} surfaces. A Pt{dollar}sb3{dollar}Sn alloy was subsequently characterized before and after H{dollar}sb2{dollar} reduction to study its surface characteristics.; Surface characterization of Au/MnO{dollar}sb{lcub}rm x{rcub}{dollar} and MnO{dollar}sb{lcub}rm x{rcub}{dollar} was performed in order to elucidate the CO oxidation mechanism. The spectral data yield evidence that the enhanced CO oxidation activity of Au/MnO{dollar}sb{lcub}rm x{rcub}{dollar} is related to Mn present primarily as Mn{dollar}sb3{dollar}O{dollar}sb4{dollar} with substantial amounts of water or hydroxyl groups. The spectra are consistent with very small Au particles which may exist in an oxidized state. The behavior of Au/MnO{dollar}sb{lcub}rm x{rcub}{dollar} and MnO{dollar}sb{lcub}rm x{rcub}{dollar} toward an inert pretreatment suggests the possibility of a Au-MnO{dollar}sb{lcub}rm x{rcub}{dollar} interaction.