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Low temperature oxidation of carbon monoxide over alkali-metal promoted palladium-tin oxide catalysts

Karakaş, Gürkan
The CO oxidation activity of sol-gel prepared tin dioxide based palladium and sodium-palladium promoted catalysts were investigated by XRD, XPS, DRIFTS and temperature programmed desorption techniques. XPS data suggests that alkali-metal promotion results in the formation of super-oxide species and promotes the surface segregation of Pd atoms, increasing the number of active sites for CO adsorption/oxidation. The formation of a ternary oxide of sodium and palladium is Postulated. Through sub-ambient TPD experiments, the noble metal promoted catalysts have been identified to exhibit CO oxidation activity below ambient temperature. Steady-state CO conversion and rate of reaction data revealed that improvements in the CO oxidation activity of palladized tin dioxide could be achieved under both oxygen-rich and oxygen-lean conditions by sodium-promotion of the catalyst.