Gold catalysts, supported conversion

Curves (a) and (b) in Fig. 5.3 compare the light-off curves for the gold catalysts supported on anatase and brookite after being treated with O2 at 300°C. Interestingly, the catalytic activity of the brookite-supported gold catalyst remained highly active, with the onset for 100% CO conversion occurring around —20°C. In contrast, the onset... 

CO conversions over Au/Ce02 catalyst were measured in the dry and wet condition as shown in Fig. 1. Similar to other supported gold catalysts, Au/Ce02 catalyst showed higher CO conversions in the presence of water vapor than in the absence of it at the same temperature. Catalytic activities for CO oxidation over Au/Ce02 catalysts prepared at different calcinations temperature were compared in the dry and wet condition as shown in Fig. 2. Au/Ce02 catalyst calcined at 473 K showed the highest initial CO conversion in the absence of water vapor. However, the CO conversion decreased steadily and reached a steady-state value over this catalyst. 

Figure 9. CO conversion as a function of temperature for supported gold catalysts (a) Au/Zr02, (b) Au/Ti02 (both PVA protected) (Reprinted from Reference [24], 2006, with permission from American Chemical Society).

In a recent study, Xu et al. managed to lower temperatures to 100 °C by using gold catalyst and oxygen as oxidant. The authors compared the Au/C catalyst and supported Pd or Pt catalysts, and concluded that these systems offered similar performance and that selectivity generally depended on cyclohexene conversion [226]. 

Figure 3.13 Relationship between conversion in CO oxidation at room temperature and the temperature for 10% conversion (Tio) in propane oxidation. Symbols Supports (open symbols), gold catalyst prepared by co-precipitation (filled symbols). Reaction...

Figure 10.6 Conversion as a function of temperature for various supported gold catalysts (1) A11/FC2O3 (2) Au/Fe203-Zn0 (3) Au/Fe203-ZrC>2 (4) Au/ZrC>2 all were made by DP onto freshly precipitated hydroxides. Conditions similar to those of Figure 10.5.

High catalytic activity for gold catalysts in the WGS was found by Andreeva and co-workers using Fe20s as a support [219,220,222]. Over this catalyst, CO conversion started at 393 K (see Fig. 6.5), and its activity exceeded that of the most efficient industrial WGS catalyst known at that time. 

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