Low temperature carbon monoxide oxidation over gold nanoparticles supported on sodium titanate nanotubes

Small gold particles having sizes of 1.0–2.0 nm were deposited on the surface of the sodium trititanate (Na2Ti3O7) nanotube by the ion exchange method. This nanotube-supported gold catalyst was able to oxidize CO at the sub-ambient temperature. In a pulse reactor, the gold catalyst could achieve a T50% of 218 K using 1.0 vol.% CO/He gas pulses (0.34 μmol CO/pulse). In the Au loadings of 0.39–2.53 wt.%, the activity of the gold catalyst increased with the gold loading. Calcination of nanotube support at higher than 383 K prior to the gold deposition produced a catalyst with a lower activity. Regarding the effect of calcining the gold particles on the activity (with NaTNT support calcined at 673 K), the catalyst with gold particles heated at 383 K only exhibited the best CO oxidation activity. XPS indicated that there are three gold species with different oxidation state, Au0, Au+1 and Auδ−, in the calcined gold catalysts. As calcination temperature increased, the Au0 concentration increased at the consumption of Au+1 species, while the Auδ− concentration remained relatively constant. This fact strongly suggested that Au+1 species must play an important role in the activity in the sub-ambient temperature region.

Graphical abstractSmall gold particles having sizes of 1.0–2.0 nm were deposited on the sodium trititanate nanotube (Na2Ti3O7) surface by the ion exchange method. The gold catalyst with a loading of 2.53 wt.% Au could achieve a T50% of 218 K in a pulse reactor with a reactant pulse containing 0.34 μmol CO/pulse.Figure optionsDownload full-size imageDownload as PowerPoint slide