Catalytic behavior of gold nanoparticles supported on a TiO2-Al2O3 mixed oxide for CO oxidation at low temperature

The present work highlights the versatility of a TiO2-Al2O3 mixed oxide bearing highly dispersed gold nanoparticles that was applied in the CO oxidation reaction at room temperature. The TiO2, Al2O3, and TiO2-Al2O3 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 TiO2-Al2O3 support on the activity of gold catalysts with respect to TiO2 and Al2O3 was observed; Au/TiO2-Al2O3 showed outstanding CO oxidation, being active from 0 degrees C and stable throughout a 24-h test. As for the alumina content (5, 10, and 15 wt.%) in TiO2 , it improved the textural properties by retarding the crystal growth and anatase-rutile phase transformation of TiO2, 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(2 )was used to treat thermally the Au/TiO2-Al2O3 , Au/TiO2, and Au/Al2O3 materials. In addition, the XPS technique helped elicit that Au-0 and Au1+ boosted their interaction with the TiO2, Al2O3 , and TiO2-Al2O3 supports by means of charge transfer, which resulted in outstanding CO oxidation activity from 0 degrees 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.