Gold catalysts colloids

J. D. Grunwaldt, C. Kiener, C. Wogerbauer, and A. Baiker, Preparation of supported gold catalysts for low-temperature CO oxidation via size-controlled gold colloids, J. Catal. 181(2), 223—232 (1999). 

Several methods are available for preparing supported metal catalysts. Commonly used methods include impregnation to incipient wetness, deposition-precipitation (DP), coprecipitation, and deposition/immobilization of colloidal metals. A useful description of such techniques is reported for gold catalysts [43]. 

Developing the sol immobilisation technique described in Section 13.2 and increasing our ability in preparing small colloidal gold particles, we were able to implement the activity of the gold catalyst from a few hundred TOP units up to 3500 h" in the case of glycolate and 2000 h in the case of lactate. Selectivity data, evaluated at 100% conversion, were exceptionally high, whereas a lower selectivity was observed in the case of Pd and Pt catalysts. 

The colloidal route is an attractive strategy to prepare supported gold catalysts since metal particles of controlled size and narrow size distribution are formed... 

Table 17.5 Examples of conditions of preparation of supported gold catalysts from colloidal gold route. 

Different methods for the preparation of gold catalysts (mono and bimetallic) were used - the modified deposition-precipitation (MDP), the deposition-precipitation by ammonia (DPA) and the colloidal method (CM). The catalytic performances of all samples were evaluated in the catalytic wet air oxidation (CWAO) of succinic acid under mild conditions (190°C, 50 bar total pressure). The results showed that the preparation procedure and the addition of a second metal (Pt or Ru) clearly influence the catdytic activity and selectivity, depending on the size of the gold particles and the nature of the second metal. 

Gold Colloidal Nanoparticles Sized to be Suitable Precursors for Heterogeneous Catalysts... 

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