Catalytic behavior of gold nanoparticles supported on a TiO-AlO mixed oxide for CO oxidation at low temperature.

The present work highlights the versatility of a TiO-AlO mixed oxide bearing highly dispersed gold nanoparticles that was applied in the CO oxidation reaction at room temperature. The TiO, AlO, and TiO-AlO supports were synthesized by the sol-gel method, while gold nanoparticles were added by the deposition-precipitation with urea method using a theoretical Au loading of 2 wt.%. A promotional effect of the TiO-AlO support on the activity of gold catalysts with respect to TiO and AlO was observed; Au/TiO-AlO showed outstanding CO oxidation, being active from 0 °C and stable throughout a 24-h test. As for the alumina content (5, 10, and 15 wt.%) in TiO, it improved the textural properties by retarding the crystal growth and anatase-rutile phase transformation of TiO, suppressing the deposition of carbon on the catalyst surface and stabilizing the Au nanoparticles even at high temperatures. Gold was highly dispersed with nanoparticle sizes ranging from 1 to 2 nm when H was used to treat thermally the Au/TiO-AlO, Au/TiO and Au/AlO materials. In addition, the XPS technique helped elicit that Au and Au boosted their interaction with the TiO, AlO, and TiO-AlO supports by means of charge transfer, which resulted in outstanding CO oxidation activity from 0 °C. Likewise, the key factors that control the peculiar catalytic performance in the CO oxidation reaction are discussed, which represents a step forward in the versatility behavior of gold catalysts supported on mixed oxide catalysts.