Efficient CO (carbon monoxide) oxidation using gold catalysts supported on WO3/titanate protonated nanotubes

WO₃/titanate protonated nanotubes used to disperse gold nanoparticles were prepared by the deposition-precipitation with urea method and tested in CO oxidation reaction. Remarkably enhanced CO oxidation activity was achieved with the addition of gold nanoparticles with respect to WO₃/NT and Au/NT catalysts. XPS and H₂/TPR showed that when the samples were activated at 400 °C under hydrogen treatment, gold was present in the metallic Au⁰ form and tungsten as W⁵⁺ and W⁶⁺ species; likewise, the addition of tungsten to the tubular morphology led to the formation of vacancies and new adsorption sites, preserving the structure at up to 400 °C. The interaction between WO₃ and the titanate nanotubes was improved by adding gold nanoparticles with sizes around 1 and 3 nm under hydrogen treatment, increasing the content of reduced W⁵⁺ species that promoted the CO oxidation at low temperatures. The 2Au-3WO₃/NT catalyst was active from 0 °C and showed temporary stability at room temperature.