Gold catalysts complete oxidation

For CP gold catalysts re-oxidation in the deeper ceria layers cannot be completely achieved even during HT re-oxidation (compare with the TPR data listed in Table 10.4). With MA, the OSC remains practically unchanged during the redox cycle into the temperature range of interest for WGSR. ... 

Supported gold catalysts are, in general, less active than platinum group metal catalysts in the complete oxidation of hydrocarbons however, by choosing... 

The experimental results presented above clearly show that there are three important controlling factors which determine the catal3d ic properties of gold supported on metal oxides for oxidation. The first is the selection of suitable metal oxide supports. In the complete oxidation (combustion) of CO and nitrogen-containing organic compounds like trimethylamine gold catalysts are... 

Gold as a VOC Destruction Catalyst. - Continued research into the use of noble metal catalysts for complete oxidation reactions is required to determine the composition of catalysts most active for the process and the mechanism by which these operate. In spite of considerable research into alternative supports, varied noble metal loadings, etc., the susceptibility to deactivation of these catalysts remains a problem, particularly in the oxidation of chlorinated compounds. For this reason, alternative classes of catalysts active for VOC combustion are required. 

The gold atoms in the Au/Ce02(lll) and Au/ZnO(OOOT) catalysts were probably not oxidized during the WGS process." After reaction, XPS showed Au 4f positions that were almost identical to those seen upon deposition of gold on the oxides and very different from those typically seen for AnO species. Post-reacdon surface analysis also showed the presence of formate- and/or carbonate-like groups on the surface of the catalysts. Possible reaction paths for the formation of these groups are discussed in the work by Burch. It is not completely clear if they are key intermediates in the WGS process or simple spectators. ... 

Strongly adsorbed surface intermediates. No activity for electrooxidation in solution for gold catalyst in acidic media-complete absence of gold oxide peak B. 

The present studies exhibited the prospects of the method of deposition-precipitation with ammonia for the gold catalyst preparation using [Au(NH3)4] synthesiz from HAuCk solution. As compared with the previously published DP ns procedures, the proposed procedure makes possible almost complete deposition (>99%) of gold from HAuCk solution on the Si02 and Ti02 supports at the low ratio NH3 Au = 6.5-7 and pH<6. The highly dispersed gold particles are catalytically active in the liquid phase oxidation of piperonyl alcohol to aldehyde and in the S-VOC removal. 

---